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Effect of Application of Probiotic Pollen Suspension on Immune Response and Gut Microbiota of [START]Honey Bees[END] ([START]Apis mellifera[END]). Although the use of probiotic bacteria in invertebrates is still rare, scientists have begun to look into their usage in [START]honey bees[END]. The probiotic preparation, based on the autochthonous strain Lactobacillus brevis B50 Biocenol (CCM 8618), which was isolated from the digestive tracts of healthy [START]bees[END], was applied to the bee colonies in the form of a pollen suspension. Its influence on the immune response was determined by monitoring the expression of genes encoding immunologically important molecules in the [START]honey bee[END] intestines. Changes in the intestinal microbiota composition were also studied. The results showed that the probiotic Lact. brevis B50, on a pollen carrier, significantly increased the expression of genes encoding antimicrobial peptides (abaecin, defensin-1) as well as pattern recognition receptors (toll-like receptor, peptidoglycan recognition proteins). Gene expression for the other tested molecules included in Toll and Imd signaling pathways (dorsal, cactus, kenny, relish) significantly changed during the experiment. The positive effect on intestinal microbiota was manifested mainly by a significant increase in the ratio of lactic acid bacteria to enterobacteria. These findings confirm the potential of the tested probiotic preparation to enhance immunity in bee colonies and thus increase their resistance to infectious diseases and stress conditions.

Side-effects of thiamethoxam on the brain andmidgut of the africanized honeybee [START]Apis mellifera[END] (Hymenopptera: Apidae). The development of agricultural activities coincides with the increased use of pesticides to control pests, which can also be harmful to nontarget insects such as [START]bees[END]. Thus, the goal of this work was assess the toxic effects of thiamethoxam on newly emerged worker [START]bees[END] of [START]Apis mellifera[END] (africanized honeybee-AHB). Initially, we determined that the lethal concentration 50 (LC50 ) of thiamethoxam was 4.28 ng a.i./muL of diet. To determine the lethal time 50 (LT50 ), a survival assay was conducted using diets containing sublethal doses of thiamethoxam equal to 1/10 and 1/100 of the LC50. The group of [START]bees[END] exposed to 1/10 of the LC50 had a 41.2% reduction of lifespan. When AHB samples were analyzed by morphological technique we found the presence of condensed cells in the mushroom bodies and optical lobes in exposed [START]honeybees[END]. Through Xylidine Ponceau technique, we found cells which stained more intensely in groups exposed to thiamethoxam. The digestive and regenerative cells of the midgut from exposed [START]bees[END] also showed morphological and histochemical alterations, like cytoplasm vacuolization, increased apocrine secretion and increased cell elimination. Thus, intoxication with a sublethal doses of thiamethoxam can cause impairment in the brain and midgut of AHB and contribute to the [START]honeybee[END] lifespan reduction.

Lateralization of olfaction in the [START]honeybee[END] [START]Apis mellifera[END]. Lateralization of function is a well-known phenomenon in humans. The two hemispheres of the human brain are functionally specialized such that certain cognitive skills, such as language or musical ability, conspecific recognition, and even emotional responses, are mediated by one hemisphere more than the other [1, 2]. Studies over the past 30 years suggest that lateralization occurs in other vertebrate species as well [3-11]. In general, lateralization is observed in different sensory modalities in humans as well as vertebrates, and there are interesting parallels (reviewed in [12]). However, little is known about functional asymmetry in invertebrates [13, 14] and there is only one investigation in insects [15]. Here we show, for the first time, that the [START]honeybee[END] [START]Apis mellifera[END] displays a clear laterality in responding to learned odors. By training [START]honeybees[END] on two different versions of the well-known proboscis extension reflex (PER) paradigm [16, 17], we demonstrate that [START]bees[END] respond to odors better when they are trained through their right antenna. To our knowledge, this is the first demonstration of asymmetrical learning performance in an insect.

[START]Apis mellifera[END] [START]bees[END] acquire long-term olfactory memories within the colony. Early studies indicate that [START]Apis mellifera[END] [START]bees[END] learn nectar odours within their colonies. This form of olfactory learning, however, has not been analysed by measuring well-quantifiable learning performances and the question remains whether it constitutes a 'robust' form of learning. Hence, we asked whether [START]bees[END] acquire long-term olfactory memories within the colony. To this end, we used the bee proboscis extension response. We found that within-the-nest [START]bees[END] do indeed associate the odour (as the conditioned stimulus) with the sugar (as the unconditioned stimulus) present in the incoming nectar, and that the distribution of scented nectar within the colony allows them to establish long-term olfactory memories. This finding is discussed in the context of efficient foraging.

Pathway profiles based on gene-set enrichment analysis in the [START]honey bee[END] [START]Apis mellifera[END] under brood rearing-suppressed conditions. Perturbation of normal behaviors in [START]honey bee[END] colonies by any external factor can immediately reduce the colony's capacity for brood rearing, which can eventually lead to colony collapse. To investigate the effects of brood-rearing suppression on the biology of [START]honey bee[END] workers, gene-set enrichment analysis of the transcriptomes of worker [START]bees[END] with or without suppressed brood rearing was performed. When brood rearing was suppressed, pathways associated with both protein degradation and synthesis were simultaneously over-represented in both nurses and foragers, and their overall pathway representation profiles resembled those of normal foragers and nurses, respectively. Thus, obstruction of normal labor induced over-representation in pathways related with reshaping of worker bee physiology, suggesting that transition of labor is physiologically reversible. In addition, some genes associated with the regulation of neuronal excitability, cellular and nutritional stress and aggressiveness were over-expressed under brood rearing suppression perhaps to manage in-hive stress under unfavorable conditions.

Comparison of the energetic stress associated with experimental Nosema ceranae and Nosema apis infection of [START]honeybees[END] ([START]Apis mellifera[END]). Nosema ceranae is a relatively new and widespread parasite of the western [START]honeybee[END] [START]Apis mellifera[END] that provokes a new form of nosemosis. In comparison to Nosema apis, which has been infecting the [START]honeybee[END] for much longer, N. ceranae seems to have co-evolved less with this host, causing a more virulent disease. Given that N. apis and N. ceranae are obligate intracellular microsporidian parasites, needing host energy to reproduce, energetic stress may be an important factor contributing to the increased virulence observed. Through feeding experiments on caged [START]bees[END], we show that both mortality and sugar syrup consumption were higher in N. ceranae-infected [START]bees[END] than in N. apis-infected and control [START]bees[END]. The mortality and sugar syrup consumption are also higher in N. apis-infected [START]bees[END] than in controls, but are less than in N. ceranae-infected [START]bees[END]. With both microsporidia, mortality and sugar syrup consumption increased in function of the increasing spore counts administered for infection. The differences in energetic requirements between both Nosema spp. confirm that their metabolic patterns are not the same, which may depend critically on host-parasite interactions and, ultimately, on host pathology. The repercussions of this increased energetic stress may even explain the changes in host behavior due to starvation, lack of thermoregulatory capacity, or higher rates of trophallaxis, which might enhance transmission and bee death.

Magnetoreception system in [START]honeybees[END] ([START]Apis mellifera[END]). [START]Honeybees[END] ([START]Apis mellifera[END]) undergo iron biomineralization, providing the basis for magnetoreception. We showed earlier the presence of superparamagnetic magnetite in iron granules formed in [START]honeybees[END], and subscribed to the notion that external magnetic fields may cause expansion or contraction of the superparamagnetic particles in an orientation-specific manner, relaying the signal via cytoskeleton (Hsu and Li 1994). In this study, we established a size-density purification procedure, with which quantitative amount of iron granules was obtained from [START]honey bee[END] trophocytes and characterized; the density of iron granules was determined to be 1.25 g/cm(3). While we confirmed the presence of superparamagnetic magnetite in the iron granules, we observed changes in the size of the magnetic granules in the trophycytes upon applying additional magnetic field to the cells. A concomitant release of calcium ion was observed by confocal microscope. This size fluctuation triggered the increase of intracellular Ca(+2) , which was inhibited by colchicines and latrunculin B, known to be blockers for microtubule and microfilament syntheses, respectively. The associated cytoskeleton may thus relay the magnetosignal, initiating a neural response. A model for the mechanism of magnetoreception in [START]honeybees[END] is proposed, which may be applicable to most, if not all, magnetotactic organisms.

MRJP microsatellite markers in Africanized [START]Apis mellifera[END] colonies selected on the basis of royal jelly production. It is important to select the best [START]honeybees[END] that produce royal jelly to identify important molecular markers, such as major royal jelly proteins (MRJPs), and hence contribute to the development of new breeding strategies to improve the production of this substance. Therefore, this study focused on evaluating the genetic variability of mrjp3, mrjp5, and mrjp8 and associated allele maintenance during the process of selective reproduction in Africanized [START]Apis mellifera[END] individuals, which were chosen based on royal jelly production. The three loci analyzed were polymorphic, and produced a total of 16 alleles, with 4 new alleles, which were identified at mrjp5. The effective number of alleles at mrjp3 was 3.81. The observed average heterozygosity was 0.4905, indicating a high degree of genetic variability at these loci. The elevated FIS values for mrjp3, mrjp5, and mrjp8 (0.4188, 0.1077, and 0.2847, respectively) indicate an excess of homozygotes. The selection of Africanized [START]A. mellifera[END] queens for royal jelly production has maintained the mrjp3 C, D, and E alleles; although, the C allele occurred at a low frequency. The heterozygosity and FIS values show that the genetic variability of the queens is decreasing at the analyzed loci, generating an excess of homozygotes. However, the large numbers of drones that fertilize the queens make it difficult to develop homozygotes at mrjp3. Mating through instrumental insemination using the drones of known genotypes is required to increase the efficiency of Africanized [START]A. mellifera[END]-breeding programs, and to improve the quality and efficiency of commercial royal jelly apiaries.

Different [START]bees[END], different needs: how nest-site requirements have shaped the decision-making processes in homeless [START]honeybees[END] (Apis spp.). During reproductive swarming, a [START]honeybee[END] swarm needs to decide on a new nest site and then move to the chosen site collectively. Most studies of swarming and nest-site selection are based on one species, [START]Apis mellifera[END] Natural colonies of [START]A. mellifera[END] live in tree cavities. The quality of the cavity is critical to the survival of a swarm. Other [START]honeybee[END] species nest in the open, and have less strict nest-site requirements, such as the open-nesting dwarf honeybee Apis floreaApis florea builds a nest comprised of a single comb suspended from a twig. For a cavity-nesting species, there is only a limited number of potential nest sites that can be located by a swarm, because suitable sites are scarce. By contrast, for an open-nesting species, there is an abundance of equally suitable twigs. While the decision-making process of cavity-nesting [START]bees[END] is geared towards selecting the best site possible, open-nesting species need to coordinate collective movement towards areas with potential nest sites. Here, we argue that the nest-site selection processes of A. florea and [START]A. mellifera[END] have been shaped by each species' specific nest-site requirements. Both species use the same behavioural algorithm, tuned to allow each species to solve their species-specific problem.This article is part of the theme issue 'Collective movement ecology'.

Tolerance and response of two [START]honeybee[END] species Apis cerana and [START]Apis mellifera[END] to high temperature and relative humidity. The ambient temperature and relative humidity affect the metabolic and physiological responses of [START]bees[END], thus affecting their life activities. However, the physiological changes in bee due to high temperature and high humidity remain poorly understood. In this study, we explored the effects of higher temperature and humidity on the epiphysiology of [START]bees[END] by evaluating the survival, tolerance and body water loss in two bee species (Apis cerana and [START]Apis mellifera[END]). We also evaluated the changes in the activity of antioxidant and detoxification enzymes in their body. We observed that under higher temperature and humidity conditions, the survival rate of [START]A. mellifera[END] was higher than that of A. cerana. On the other hand, a comparison of water loss between the two species revealed that [START]A. mellifera[END] lost more water. However, under extremely high temperature conditions, A. cerana was more tolerant than [START]A. mellifera[END]. Moreover, under higher temperature and humidity conditions, the activity of antioxidant and detoxification enzymes in [START]bees[END] was significantly increased. Overall, these results suggest that high temperatures can adversely affect [START]bees[END]. They not only affect the survival and water loss, but also stimulate oxidative stress in [START]bees[END]. However, unlike our previous understanding, high humidity can also adversely affect [START]bees[END], although its effects are lower than that of temperature.

Go East for Better [START]Honey Bee[END] Health: Apis cerana Is Faster at Hygienic Behavior than [START]A. mellifera[END]. The poor health status of the [START]Western honey bee[END], [START]Apis mellifera[END], compared to its Eastern counterpart, Apis cerana, is remarkable. This has been attributed to lower pathogen prevalence in A. cerana colonies and to their ability to survive infestations with the ectoparasitic mite, Varroa destructor. These properties have been linked to an enhanced removal of dead or unhealthy immature [START]bees[END] by adult workers in this species. Although such hygienic behavior is known to contribute to [START]honey bee[END] colony health, comparative data of [START]A. mellifera[END] and A. cerana in performing this task are scarce. Here, we compare for the first time the removal of freeze-killed brood in one population of each species and over two seasons in China. Our results show that A. cerana was significantly faster than [START]A. mellifera[END] at both opening cell caps and removing freeze-killed brood. The fast detection and removal of diseased brood is likely to limit the proliferation of pathogenic agents. Given our results can be generalized to the species level, a rapid hygienic response could contribute to the better health of A. cerana. Promoting the fast detection and removal of worker brood through adapted breeding programs could further improve the social immunity of A. mellifera colonies and contribute to a better health status of the [START]Western honey bee[END] worldwide.

The absolute configurations of hydroxy fatty acids from the royal jelly of [START]honeybees[END] ([START]Apis mellifera[END]). 9-Hydroxy-2E-decenoic acid (9-HDA) is a precursor of the queen-produced substance, 9-oxo-2E-decenoic acid (9-ODA), which has various important functions and roles for caste maintenance in [START]honeybee[END] colonies ([START]Apis mellifera[END]). 9-HDA in royal jelly is considered to be a metabolite of 9-ODA produced by worker [START]bees[END], and it is fed back to the queen who then transforms it into 9-ODA. Recently we found that 9-HDA is present in royal jelly as a mixture of optical isomers (R:S, 2:1). The finding leads us to suspect that chiral fatty acids in royal jelly are precursors of semiochemicals. Rather than looking for semiochemicals in the mandibular glands of the queen bee, this study involves the search for precursors of pheromones from large quantities of royal jelly. Seven chiral hydroxy fatty acids, 9,10-dihydroxy-2E-decenoic, 4,10-dihydroxy-2E-decenoic, 4,9-dihydroxy-2E-decenoic, 3-hydroxydecanoic, 3,9-dihydroxydecanoic, 3,11-dihydroxydodecanoic, and 3,10-dihydroxydecanoic acids were isolated. The absolute configurations of these acids were determined using the modified Mosher's method, and it was revealed that, similar to 9-HDA, five acids are present in royal jelly as mixtures of optical isomers.

Influence of the insecticide pyriproxyfen on the flight muscle differentiation of [START]Apis mellifera[END] (Hymenoptera, Apidae). The Brazilian africanized [START]Apis mellifera[END] is currently considered as one of the most important pollinators threatened by the use of insecticides due to its frequent exposition to their toxic action while foraging in the crops it pollinated. Among the insecticides, the most used in the control of insect pragues has as active agent the pyriproxyfen, analogous to the juvenile hormone (JH). Unfortunately the insecticides used in agriculture affect not only the target insects but also beneficial nontarget ones as [START]bees[END] compromising therefore, the growth rate of their colonies at the boundaries of crop fields. Workers that forage for provisions in contaminated areas can introduce contaminated pollen or/and nectar inside the beehives. As analogous to JH the insecticide pyriproxyfen acts in the bee's larval growth and differentiation during pupation or metamorphosis timing. The flighty muscle is not present in the larvae wingless organisms, but differentiates during pupation/metamorphosis. This work aimed to investigate the effect of pyriproxyfen insecticide on differentiation of such musculature in workers of Brazilian africanized [START]honey bees[END] fed with artificial diet containing the pesticide. The results show that the [START]bees[END] fed with contaminated diet, independent of the insecticide concentration used, show a delay in flight muscle differentiation when compared to the control.

New bioassay cage methodology for in vitro studies on Varroa destructor and [START]Apis mellifera[END]. Varroa destructor Anderson and Trueman, is an ectoparasitic mite of [START]honey bees[END], [START]Apis mellifera[END] L., that has been considered a major cause of colony losses. Synthetic miticides have been developed and registered to manage this ectoparasite, however, resistance to registered pyrethroid and organophosphate Varroacides have already been reported in Canada. To test toxicity of miticides, current contact-based bioassay methods are designed to evaluate mites and [START]bees[END] separately, however, these methods are unlikely to give an accurate depiction of how miticides interact at the colony level. Therefore, the objective of this study was to develop a bioassay cage for testing the toxicity of miticides on [START]honey bees[END] and Varroa mites simultaneously using amitraz as a reference chemical. A 800 mL polypropylene plastic cage holding 100-150 [START]bees[END] was designed and officially named "Apiarium". A comparison of the effects of three subsequent dilutions of amitraz was conducted on: Varroa mites placed in glass vials, [START]honey bees[END] in glass Mason jars, and Varroa-infested [START]bees[END] in Apiariums. Our results indicated cumulative Varroa mortality was dose-dependent in the Apiarium after 4 h and 24 h assessments. Apiarium and glass vial treatments at 24 h also had high mite mortality and a positive polynomial regression between Varroa mortality and amitraz dose rates. Moreover, chemical application in the Apiarium was less toxic for [START]bees[END] compared to the Mason jar method. Considering these results, the Apiarium bioassay provides a simple, cheap and reliable method for simultaneous chemical screening on V. destructor and [START]A. mellifera[END]. Furthermore, as mites and [START]bees[END] are tested together, the Apiarium simulates a colony-like environment that provides a necessary bridge between laboratory bioassay testing and full field experimentation. The versatility of the Apiarium allows researchers to test a multitude of different [START]honey bee[END] bioassay experiments including miticide screening, delivery methods for chemical products, or development of new mite resistance-testing methodology.

LC-MS/MS Quantification Reveals Ample Gut Uptake and Metabolization of Dietary Phytochemicals in [START]Honey Bees[END] ([START]Apis mellifera[END]). The [START]honey bee[END] pollen/nectar diet is rich in bioactive phytochemicals and recent studies have demonstrated the potential of phytochemicals to influence [START]honey bee[END] disease resistance. To unravel the role of dietary phytochemicals in [START]honey bee[END] health it is essential to understand phytochemical uptake, bioavailability, and metabolism but presently limited knowledge exists. With this study we aim to build a knowledge foundation. For 5 days, we continuously fed [START]honey bees[END] on eight individual phytochemicals and measured the concentrations in whole and dissected [START]bees[END] by HPLC-MS/MS. Ample phytochemical metabolization was observed, and only 6-30% of the consumed quantities were recovered. Clear differences in metabolization rates were evident, with atropine, aucubin, and triptolide displaying significantly slower metabolism. Phytochemical gut uptake was also demonstrated, and oral bioavailability was 4-31%, with the highest percentages observed for amygdalin, triptolide, and aucubin. We conclude that differences in the chemical properties and structure impact phytochemical uptake and metabolism.

[Ethological-physiological effects of hypoxia on the [START]honeybee[END] [START]Apis mellifera[END] L]. Information on the effect of hypoxia on the behavior and physiological state of the [START]honeybee[END] was compiled and systematized. It was shown that, in the course of colonization of temperate and cold climate zones by the [START]honeybee[END], natural selection favored the acquisition of an effective mechanism of thermoregulation and high tolerance to hypoxia. It was noted that [START]bees[END] can develop under conditions when the CO2 concentration exceeds the content of this gas in the surface layer of the Earth by more than three orders of magnitude; however, this leads to deviations in the morphometric traits from the norm. At the adult stage, anesthesia with carbon dioxide was found to reduce the body weight and the water content in it. It was shown that the effect of anesthesia in adult [START]bees[END] increases with temperature and that hypoxia in adult [START]bees[END] and queens accelerates their senescence and reduces viability.

Chemical Stimulants and Stressors Impact the Outcome of Virus Infection and Immune Gene Expression in [START]Honey Bees[END] ([START]Apis mellifera[END]). Western [START]honey bees[END] ([START]Apis mellifera[END]) are ecologically, agriculturally, and economically important plant pollinators. High average annual losses of [START]honey bee[END] colonies in the US have been partially attributed to agrochemical exposure and virus infections. To examine the potential negative synergistic impacts of agrochemical exposure and virus infection, as well as the potential promise of phytochemicals to ameliorate the impact of pathogenic infections on [START]honey bees[END], we infected [START]bees[END] with a panel of viruses (i.e., Flock House virus, deformed wing virus, or Sindbis virus) and exposed to one of three chemical compounds. Specifically, [START]honey bees[END] were fed sucrose syrup containing: (1) thyme oil, a phytochemical and putative immune stimulant, (2) fumagillin, a beekeeper applied fungicide, or (3) clothianidin, a grower-applied insecticide. We determined that virus abundance was lower in [START]honey bees[END] fed 0.16 ppm thyme oil augmented sucrose syrup, compared to [START]bees[END] fed sucrose syrup alone. Parallel analysis of [START]honey bee[END] gene expression revealed that [START]honey bees[END] fed thyme oil augmented sucrose syrup had higher expression of key RNAi genes (argonaute-2 and dicer-like), antimicrobial peptide expressing genes (abaecin and hymenoptaecin), and vitellogenin, a putative [START]honey bee[END] health and age indicator, compared to [START]bees[END] fed only sucrose syrup. Virus abundance was higher in [START]bees[END] fed fumagillin (25 ppm or 75 ppm) or 1 ppb clothianidin containing sucrose syrup relative to levels in [START]bees[END] fed only sucrose syrup. Whereas, [START]honey bees[END] fed 10 ppb clothianidin had lower virus levels, likely because consuming a near lethal dose of insecticide made them poor hosts for virus infection. The negative impact of fumagillin and clothianidin on [START]honey bee[END] health was indicated by the lower expression of argonaute-2, dicer-like, abaecin, and hymenoptaecin, and vitellogenin. Together, these results indicate that chemical stimulants and stressors impact the outcome of virus infection and immune gene expression in [START]honey bees[END].

Nitenpyram disturbs gut microbiota and influences metabolic homeostasis and immunity in [START]honey bee[END] ([START]Apis mellifera[END] L.). Recently, environmental risk and toxicity of neonicotinoid insecticides to [START]honey bees[END] have attracted extensive attention. However, toxicological understanding of neonicotinoid insecticides on gut microbiota is limited. In the present study, [START]honey bees[END] ([START]Apis mellifera[END] L.) were exposed to a series of nitenpyram for 14 days. Results indicated that nitenpyram exposure decreased the survival and food consumption of [START]honey bees[END]. Furthermore, 16S rRNA gene sequencing revealed that nitenpyram caused significant alterations in the relative abundance of several key gut microbiotas, which contribute to metabolic homeostasis and immunity. Using high-throughput RNA-Seq transcriptomic analysis, we identified a total of 526 differentially expressed genes (DEGs) that were significantly altered between nitenpyram-treated and control [START]honey bee[END] gut, including several genes related to metabolic, detoxification and immunity. In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed nitenpyram affected several biological processes, of which most were related to metabolism. Collectively, our study demonstrates that the dysbiosis of gut microbiota in [START]honey bee[END] caused by nitenpyram may influence metabolic homeostasis and immunity of [START]bees[END], and further decrease food consumption and survival of [START]bees[END].

[START]Honey bee[END] ([START]Apis mellifera[END]) larval pheromones may regulate gene expression related to foraging task specialization. BACKGROUND: Foraging behavior in [START]honey bees[END] ([START]Apis mellifera[END]) is a complex phenotype that is regulated by physiological state and social signals. How these factors are integrated at the molecular level to modulate foraging behavior has not been well characterized. The transition of worker [START]bees[END] from nursing to foraging behaviors is mediated by large-scale changes in brain gene expression, which are influenced by pheromones produced by the queen and larvae. Larval pheromones can also stimulate foragers to leave the colony to collect pollen. However, the mechanisms underpinning this rapid behavioral plasticity in foragers that specialize in collecting pollen over nectar, and how larval pheromones impact these different behavioral states, remains to be determined. Here, we investigated the patterns of gene expression related to rapid behavioral plasticity and task allocation among [START]honey bee[END] foragers exposed to two larval pheromones, brood pheromone (BP) and (E)-beta-ocimene (EBO). We hypothesized that both pheromones would alter expression of genes in the brain related to foraging and would differentially impact brain gene expression depending on foraging specialization. RESULTS: Combining data reduction, clustering, and network analysis methods, we found that foraging preference (nectar vs. pollen) and pheromone exposure are each associated with specific brain gene expression profiles. Furthermore, pheromone exposure has a strong transcriptional effect on genes that are preferentially expressed in nectar foragers. Representation factor analysis between our study and previous landmark [START]honey bee[END] transcriptome studies revealed significant overlaps for both pheromone communication and foraging task specialization. CONCLUSIONS: Our results suggest that, as social signals, pheromones alter expression patterns of foraging-related genes in the bee's brain to increase pollen foraging at both long and short time scales. These results provide new insights into how social signals and task specialization are potentially integrated at the molecular level, and highlights the possible role that brain gene expression may play in [START]honey bee[END] behavioral plasticity across time scales.

[START]Honey bee[END] ([START]Apis mellifera[END]) drones survive oxidative stress due to increased tolerance instead of avoidance or repair of oxidative damage. Oxidative stress can lead to premature aging symptoms and cause acute mortality at higher doses in a range of organisms. Oxidative stress resistance and longevity are mechanistically and phenotypically linked; considerable variation in oxidative stress resistance exists among and within species and typically covaries with life expectancy. However, it is unclear whether stress-resistant, long-lived individuals avoid, repair, or tolerate molecular damage to survive longer than others. The [START]honey bee[END] ([START]Apis mellifera[END] L.) is an emerging model system that is well-suited to address this question. Furthermore, this species is the most economically important pollinator, whose health may be compromised by pesticide exposure, including oxidative stressors. Here, we develop a protocol for inducing oxidative stress in [START]honey bee[END] males (drones) via Paraquat injection. After injection, individuals from different colony sources were kept in common social conditions to monitor their survival compared to saline-injected controls. Oxidative stress was measured in susceptible and resistant individuals. Paraquat drastically reduced survival but individuals varied in their resistance to treatment within and among colony sources. Longer-lived individuals exhibited higher levels of lipid peroxidation than individuals dying early. In contrast, the level of protein carbonylation was not significantly different between the two groups. This first study of oxidative stress in male [START]honey bees[END] suggests that survival of an acute oxidative stressor is due to tolerance, not prevention or repair, of oxidative damage to lipids. It also demonstrates colony differences in oxidative stress resistance that might be useful for breeding stress-resistant [START]honey bees[END].

Transcriptome analysis of [START]Apis mellifera[END] under benomyl stress to discriminate the gene expression in response to development and immune systems. The health and safety of the [START]honeybees[END] are seriously threatened due to the abuse of chemical pesticides in modern agriculture and apiculture. In this study, the RNA Seq approach was used to assess the effects of the [START]honeybees[END] treated with benomyl. The results showed that there were a total of 11,902 differentially expressed genes (DEGs). Among them, 5,759 DEGs were up-regulated and involved in the functions of immunity, detoxification, biological metabolism, and regulation. The DEGs were clustered in the GO terms of epidermal structure and response to external stimuli, and most of the DEGs were enriched in 15 pathways, such as light conduction, MAPK, calcium ion pathway, and so on. Moreover, the pathway of the toll signal transduction was activated. The data investigated that the expression of functional genes involved in the growth, development, foraging, and immunity of [START]honeybees[END] were significantly affected by benomyl stress, which would seriously threaten the health of the [START]honeybees[END]. This study provided a theoretical basis for revealing the response mechanism of [START]honeybees[END] to pesticides stress.

Nosema ceranae parasitism impacts olfactory learning and memory and neurochemistry in [START]honey bees[END] ([START]Apis mellifera[END]). Nosema sp. is an internal parasite of the [START]honey bee[END], [START]Apis mellifera[END], and one of the leading contributors to colony losses worldwide. This parasite is found in the [START]honey bee[END] midgut and has profound consequences for the host's physiology. Nosema sp. impairs foraging performance in [START]honey bees[END], yet, it is unclear whether this parasite affects the bee's neurobiology. In this study, we examined whether Nosema sp. affects odor learning and memory and whether the brains of parasitized [START]bees[END] show differences in amino acids and biogenic amines. We took newly emerged [START]bees[END] and fed them with Nosema ceranae At approximate nurse and forager ages, we employed an odor-associative conditioning assay using the proboscis extension reflex and two bioanalytical techniques to measure changes in brain chemistry. We found that nurse-aged [START]bees[END] infected with N. ceranae significantly outperformed controls in odor learning and memory, suggestive of precocious foraging, but by forager age, infected [START]bees[END] showed deficits in learning and memory. We also detected significant differences in amino acid concentrations, some of which were age specific, as well as altered serotonin, octopamine, dopamine and l-dopa concentrations in the brains of parasitized [START]bees[END]. These findings suggest that N. ceranae infection affects [START]honey bee[END] neurobiology and may compromise behavioral tasks. These results yield new insight into the host-parasite dynamic of [START]honey bees[END] and N. ceranae, as well as the neurochemistry of odor learning and memory under normal and parasitic conditions.

Varroa destructor mite electrophysiological responses to [START]honey bee[END] ([START]Apis mellifera[END]) colony volatiles. Detection and interpretation of chemical cues is essential for Varroa destructor Anderson and Trueman, an important parasite of [START]honey bees[END] ([START]Apis mellifera[END] L.), to complete its life cycle. We collected volatiles from [START]honey bee[END] brood at various developmental stages and screened for V. destructor electrophysiological responses to these with gas chromatography-linked electrotarsal detection. Volatile collections contained several methyl-alkanes that evoked electrophysiological responses from V. destructor. Moreover, odors in [START]honey bee[END] colonies that regulate [START]honey bee[END] colony structure and function were also detected by V. destructor. Collections from mid- to late-stage larvae had detectable levels of low-volatility odors identified as components of the [START]honey bee[END] brood pheromone and branched alkanes likely originating from brood cuticle. Among these, several mid- to heavy-molecular weight compounds elicited high proportional electrophysiological responses by V. destructor relative to their abundance but could not be identified using chemical standards of previously documented [START]honey bee[END] brood odors. We suggest further investigation of these unknown volatiles and future behavioral assays to determine attractiveness/repellency (valence) of those identified through chemical standards.

Impact of Nosema ceranae and Nosema apis on individual worker [START]bees[END] of the two host species (Apis cerana and [START]Apis mellifera[END]) and regulation of host immune response. Nosema apis and Nosema ceranae are obligate intracellular microsporidian parasites infecting midgut epithelial cells of host adult [START]honey bees[END], originally [START]Apis mellifera[END] and Apis cerana respectively. Each microsporidia cross-infects the other host and both microsporidia nowadays have a worldwide distribution. In this study, cross-infection experiments using both N. apis and N. ceranae in both [START]A. mellifera[END] and A. cerana were carried out to compare pathogen proliferation and impact on hosts, including host immune response. Infection by N. ceranae led to higher spore loads than by N. apis in both host species, and there was greater proliferation of microsporidia in [START]A. mellifera[END] compared to A. cerana. Both N. apis and N. ceranae were pathogenic in both host Apis species. N. ceranae induced subtly, though not significantly, higher mortality than N. apis in both host species, yet survival of A. cerana was no different to that of [START]A. mellifera[END] in response to N. apis or N. ceranae. Infections of both host species with N. apis and N. ceranae caused significant up-regulation of AMP genes and cellular mediated immune genes but did not greatly alter apoptosis-related gene expression. In this study, A. cerana enlisted a higher immune response and displayed lower loads of N. apis and N. ceranae spores than [START]A. mellifera[END], suggesting it may be better able to defend itself against microsporidia infection. We caution against over-interpretation of our results, though, because differences between host and parasite species in survival were insignificant and because size differences between microsporidia species and between host Apis species may alternatively explain the differential proliferation of N. ceranae in [START]A. mellifera[END].

The Neuroproteomic Basis of Enhanced Perception and Processing of Brood Signals That Trigger Increased Reproductive Investment in [START]Honeybee[END] ([START]Apis mellifera[END]) Workers. The neuronal basis of complex social behavior is still poorly understood. In [START]honeybees[END], reproductive investment decisions are made at the colony-level. Queens develop from female-destined larvae that receive alloparental care from nurse [START]bees[END] in the form of ad-libitum royal jelly (RJ) secretions. Typically, the number of raised new queens is limited but genetic breeding of "royal jelly [START]bees[END]" (RJBs) for enhanced RJ production over decades has led to a dramatic increase of reproductive investment in queens. Here, we compare RJBs to unselected Italian [START]bees[END] (ITBs) to investigate how their cognitive processing of larval signals in the mushroom bodies (MBs) and antennal lobes (ALs) may contribute to their behavioral differences. A cross-fostering experiment confirms that the RJB syndrome is mainly due to a shift in nurse bee alloparental care behavior. Using olfactory conditioning of the proboscis extension reflex, we show that the RJB nurses spontaneously respond more often to larval odors compared with ITB nurses but their subsequent learning occurs at similar rates. These phenotypic findings are corroborated by our demonstration that the proteome of the brain, particularly of the ALs differs between RJBs and ITBs. Notably, in the ALs of RJB newly emerged [START]bees[END] and nurses compared with ITBs, processes of energy and nutrient metabolism, signal transduction are up-regulated, priming the ALs for receiving and processing the brood signals from the antennae. Moreover, highly abundant major royal jelly proteins and hexamerins in RJBs compared with ITBs during early life when the nervous system still develops suggest crucial new neurobiological roles for these well-characterized proteins. Altogether, our findings reveal that RJBs have evolved a strong olfactory response to larvae, enabled by numerous neurophysiological adaptations that increase the nurse [START]bees[END]' alloparental care behavior.

Comparison of learning and memory of Apis cerana and [START]Apis mellifera[END]. The [START]honeybee[END] is an excellent model organism for research on learning and memory among invertebrates. Learning and memory in [START]honeybees[END] has intrigued neuroscientists and entomologists in the last few decades, but attention has focused almost solely on the Western [START]honeybee[END], [START]Apis mellifera[END]. In contrast, there have been few studies on learning and memory in the Eastern honeybee, Apis cerana. Here we report comparative behavioral data of color and grating learning and memory for A. cerana and [START]A. mellifera[END] in China, gathered using a Y-maze apparatus. We show for the first time that the learning and memory performance of A. cerana is significantly better on both color and grating patterns than that of [START]A. mellifera[END]. This study provides the first evidence of a learning and memory difference between A. cerana and [START]A. mellifera[END] under controlled conditions, and it is an important basis for the further study of the mechanism of learning and memory in [START]honeybees[END].

Resonance frequencies of [START]honeybee[END] ([START]Apis mellifera[END]) wings. During flight, insect wings bend and twist under the influence of aerodynamic and inertial forces. We tested whether wing resonance of [START]honeybees[END] ([START]Apis mellifera[END]) matches the wingbeat frequency, against the 'stiff element' hypothesis that the wing's first longitudinal mode exceeds the wingbeat frequency. Six [START]bees[END] were immobilized with their right wing pair outspread, and stimulated with a shaker while the normal modes were recorded with a scanning Doppler laser vibrometer. The lowest normal mode of the wings was the first longitudinal bending mode and, at 602+-145 Hz, was greater than the wingbeat frequency of 234+-13.9 Hz. Higher-order normal modes of the wing tended to incorporate nodal lines in the chordwise direction of the trailing edge, suggesting that their mode shape did not strongly resemble wing deformation during flapping flight. These results support the stiff element hypothesis for [START]Apis mellifera[END].

Characterization of Apis mellifera Gastrointestinal Microbiota and Lactic Acid Bacteria for [START]Honeybee[END] Protection-A Review. Numerous [START]honeybee[END] ([START]Apis mellifera[END]) products, such as honey, propolis, and bee venom, are used in traditional medicine to prevent illness and promote healing. Therefore, this insect has a huge impact on humans' way of life and the environment. While the population of [START]A. mellifera[END] is large, there is concern that widespread commercialization of beekeeping, combined with environmental pollution and the action of bee pathogens, has caused significant problems for the health of [START]honeybee[END] populations. One of the strategies to preserve the welfare of [START]honeybees[END] is to better understand and protect their natural microbiota. This paper provides a unique overview of the latest research on the features and functioning of [START]A. mellifera[END]. [START]Honeybee[END] microbiome analysis focuses on both the function and numerous factors affecting it. In addition, we present the characteristics of lactic acid bacteria (LAB) as an important part of the gut community and their special beneficial activities for [START]honeybee[END] health. The idea of probiotics for [START]honeybees[END] as a promising tool to improve their health is widely discussed. Knowledge of the natural gut microbiota provides an opportunity to create a broad strategy for [START]honeybee[END] vitality, including the development of modern probiotic preparations to use instead of conventional antibiotics, environmentally friendly biocides, and biological control agents.

Comb construction in mixed-species colonies of [START]honeybees[END], Apis cerana and [START]Apis mellifera[END]. Comb building in mixed-species colonies of Apis cerana and [START]Apis mellifera[END] was studied. Two types of cell-size foundation were made from the waxes of these species and inserted into mixed colonies headed either by an A. cerana or an [START]A. mellifera[END] queen. The colonies did not discriminate between the waxes but the A. cerana cell-size foundation was modified during comb building by the workers of both species. In pure A. cerana colonies workers did not accept any foundation but secreted wax and built on foundation in mixed colonies. Comb building is performed by small groups of workers through a mechanism of self-organisation. The two species cooperate in comb building and construct nearly normal combs but they contain many irregular cells. In pure A. mellifera colonies, the A. cerana cell size was modified and the queens were reluctant to lay eggs on such combs. In pure A. cerana colonies, the [START]A. mellifera[END] cell size was built without any modification but these cells were used either for drone brood rearing or for food storing. The principal elements of comb-building behaviour are common to both species, which indicates that they evolved prior to and were conserved after speciation.

[START]Honey Bees[END] ([START]Apis mellifera[END]) Show a Preference for the Consumption of Ethanol. BACKGROUND: Alcohol abuse and alcoholism are significant global issues. [START]Honey bees[END] are excellent models for learning and other complex behaviors; furthermore, they share many behavioral responses to ethanol (EtOH) with humans and animal models. We develop a 2-feeder choice assay to determine whether [START]honey bees[END] will self-administer and preferentially consume solutions containing EtOH. METHODS: Gustatory responsiveness to EtOH is determined using the proboscis extension reflex and consumption assays. A 2-feeder choice assay is used to examine preference for the consumption of EtOH. Survival assays assess the metabolic and toxic effects of EtOH consumption. RESULTS: [START]Honey bees[END] find the taste of EtOH to be aversive when in water, but addition of sucrose masks the aversive taste. Even though the taste of EtOH is not appetitive, [START]honey bees[END] preferentially consume sucrose solutions containing 1.25 to 2.5% EtOH in a dose-dependent manner. Based on survival assays, [START]honey bees[END] may not be able to derive caloric value from EtOH, and EtOH concentrations of 2.5% or higher lead to significant increases in mortality. CONCLUSIONS: [START]Honey bees[END] will self-administer EtOH and show a preference for consuming solutions containing EtOH. [START]Bees[END] may not be able to efficiently utilize EtOH as an energy source, but EtOH-dependent increases in mortality complicate separating the effects of caloric value and toxicity.

Conceptual learning by miniature brains. Concepts act as a cornerstone of human cognition. Humans and non-human primates learn conceptual relationships such as 'same', 'different', 'larger than', 'better than', among others. In all cases, the relationships have to be encoded by the brain independently of the physical nature of objects linked by the relation. Consequently, concepts are associated with high levels of cognitive sophistication and are not expected in an insect brain. Yet, various works have shown that the miniature brain of [START]honeybees[END] rapidly learns conceptual relationships involving visual stimuli. Concepts such as 'same', 'different', 'above/below of' or 'left/right are well mastered by [START]bees[END]. We review here evidence about concept learning in [START]honeybees[END] and discuss both its potential adaptive advantage and its possible neural substrates. The results reviewed here challenge the traditional view attributing supremacy to larger brains when it comes to the elaboration of concepts and have wide implications for understanding how brains can form conceptual relations.

Medium for development of bee cell cultures ([START]Apis mellifera[END]: Hymenoptera: Apidae). A media for the production of cell cultures from hymenopteran species such as [START]honey bee[END], [START]Apis mellifera[END] L. (Hymenoptera: Apidae) was developed. Multiple bee cell cultures were produced when using bee larvae and pupae as starting material and modified Hert-Hunter 70 media. Cell culture systems for [START]bees[END] solves an impasse that has hindered efforts to isolate and screen pathogens which may be influencing or causing colony collapse disorder of [START]bees[END]. Multiple life stages of maturing larvae to early pupae were used to successfully establish cell cultures from the tissues of the head, thorax, and abdomen. Multiple cell types were observed which included free-floating suspensions, fibroblast-like, and epithelia-like monolayers. The final culture medium, WH2, was originally developed for hemipterans, Asian citrus psyllid, Diaphorina citri, and leafhopper, Homalodisca vitripennis cell cultures but has been shown to work for a diverse range of insect species such as [START]bees[END]. Bee cell cultures had various doubling times at 21-23 degrees C ranging from 9-15 d. Deformed wing virus was detected in the primary explanted tissues, which tested negative by rt-PCR for Israeli acute paralysis virus (IAPV), Kashmir bee virus, acute bee paralysis virus, and black queen cell virus. Culture inoculation with IAPV from an isolate from Florida field samples, was detectable in cell cultures after two subcultures. Cell culture from hymenoptera species, such as [START]bees[END], greatly advances the approaches available to the field of study on colony collapse disorders.

Hemocyte-mediated phagocytosis differs between [START]honey bee[END] ([START]Apis mellifera[END]) worker castes. [START]Honey bees[END] as other insects rely on the innate immune system for protection against diseases. The innate immune system includes the circulating hemocytes (immune cells) that clear pathogens from hemolymph (blood) by phagocytosis, nodulation or encapsulation. [START]Honey bee[END] hemocyte numbers have been linked to hemolymph levels of vitellogenin. Vitellogenin is a multifunctional protein with immune-supportive functions identified in a range of species, including the [START]honey bee[END]. Hemocyte numbers can increase via mitosis, and this recruitment process can be important for immune system function and maintenance. Here, we tested if hemocyte mediated phagocytosis differs among the physiologically different [START]honey bee[END] worker castes (nurses, foragers and winter [START]bees[END]), and study possible interactions with vitellogenin and hemocyte recruitment. To this end, we adapted phagocytosis assays, which-together with confocal microscopy and flow cytometry-allow qualitative and quantitative assessment of hemocyte performance. We found that nurses are more efficient in phagocytic uptake than both foragers and winter [START]bees[END]. We detected vitellogenin within the hemocytes, and found that winter [START]bees[END] have the highest numbers of vitellogenin-positive hemocytes. Connections between phagocytosis, hemocyte-vitellogenin and mitosis were worker caste dependent. Our results demonstrate that the phagocytic performance of immune cells differs significantly between [START]honey bee[END] worker castes, and support increased immune competence in nurses as compared to forager [START]bees[END]. Our data, moreover, provides support for roles of vitellogenin in hemocyte activity.

Mating flights select for symmetry in [START]honeybee[END] drones ([START]Apis mellifera[END]). Males of the [START]honeybee[END] ([START]Apis mellifera[END]) fly to specific drone congregation areas (DCAs), which virgin queens visit in order to mate. From the thousands of drones that are reared in a single colony, only very few succeed in copulating with a queen, and therefore, a strong selection is expected to act on adult drones during their mating flights. In consequence, the gathering of drones at DCAs may serve as an indirect mate selection mechanism, assuring that queens only mate with those individuals having a better flight ability and a higher responsiveness to the queen's visual and chemical cues. Here, we tested this idea relying on wing fluctuating asymmetry (FA) as a measure of phenotypic quality. By recapturing marked drones at a natural DCA and comparing their size and FA with a control sample of drones collected at their maternal hives, we were able to detect any selection on wing size and wing FA occurring during the mating flights. Although we found no solid evidence for selection on wing size, wing FA was found to be significantly lower in the drones collected at the DCA than in those collected at the hives. Our results demonstrate the action of selection during drone mating flights for the first time, showing that developmental stability can influence the mating ability of [START]honeybee[END] drones. We therefore conclude that selection during [START]honeybee[END] drone mating flights may confer some fitness advantages to the queens.

Mitigating effects of pollen during paraquat exposure on gene expression and pathogen prevalence in [START]Apis mellifera[END] L. [START]Honey bee[END] ([START]Apis mellifera[END] L.) populations have been experiencing notable mortality in Europe and North America. No single cause has been identified for these dramatic losses, but rather multiple interacting factors are likely responsible (such as pesticides, malnutrition, habitat loss, and pathogens). Paraquat is one of the most widely used non-selective herbicides, especially in developing countries. This herbicide is considered slightly toxic to [START]honey bees[END], despite being reported as a highly effective inducer of oxidative stress in a wide range of living systems. Here, we test the effects of paraquat on the expression of detoxification and antioxidant-related genes, as well as on the dynamics of pathogen titers. Moreover, we tested the effects of pollen as mitigating factor to paraquat exposure. Our results show significant changes in the expression of several antioxidant-related and detoxification-related genes in the presence of paraquat, as well as an increase of pathogens titers. Finally, we demonstrate a mitigating effect of pollen through the up-regulation of specific genes and improvement of survival of [START]bees[END] exposed to paraquat. The presence of pollen in the diet was also correlated with a reduced prevalence of Nosema and viral pathogens. We discuss the importance of [START]honey bees[END]' nutrition, especially the availability of pollen, on colony losses chronically reported in the USA and Europe.

Cuticular pheromones stimulate hygienic behavior in the [START]honey bee[END] ([START]Apis mellifera[END]). The health of [START]western honey bee[END] ([START]Apis mellifera[END]) colonies is challenged by the parasitic mite Varroa destructor and the numerous harmful pathogens it vectors. Selective breeding for the naturally occurring social immune trait "hygienic behavior" has emerged as one sustainable approach to reducing the mites' impact on [START]honey bees[END]. To expand our understanding of hygienic triggers and improve hygienic selection tools, we tested the hypothesis that the cuticular compounds (Z)-10-tritriacontene and (Z)-6-pentadecene, previously associated with unhealthy [START]honey bee[END] brood and/or brood targeted for hygiene, are triggers of [START]honey bee[END] hygienic behavior independent of brood health. In support of our hypothesis, application of synthetic (Z)-10-tritriacontene and (Z)-6-pentadecene onto brood and brood cell caps significantly increased hygienic behavior compared to application of similarly structured hydrocarbon controls (Z)-16-dotriacontene and (Z)-7-pentadecene. Furthermore, we demonstrate a significant positive correlation between colony-level hygienic responses to (Z)-10-tritriacontene and the traditional freeze-killed brood assay for selection of hygienic [START]honey bee[END] stocks. These results confirm biological activity of (Z)-6-pentadecene and reveal (Z)-10-tritriacontene as a novel hygiene trigger. They also support development of improved tools for [START]honey bee[END] colony monitoring and hygienic selection, and thus may accelerate development of [START]honey bee[END] stocks with greater resistance to Varroa and associated pathogens.

Gut-associated microbes of [START]Drosophila melanogaster[END]. There is growing interest in using [START]Drosophila melanogaster[END] to elucidate mechanisms that underlie the complex relationships between a host and its microbiota. In addition to the many genetic resources and tools [START]Drosophila[END] provides, its associated microbiota is relatively simple (1-30 taxa), in contrast to the complex diversity associated with vertebrates (> 500 taxa). These attributes highlight the potential of this system to dissect the complex cellular and molecular interactions that occur between a host and its microbiota. In this review, we summarize what is known regarding the composition of gut-associated microbes of [START]Drosophila[END] and their impact on host physiology. We also discuss these interactions in the context of their natural history and ecology and describe some recent insights into mechanisms by which [START]Drosophila[END] and its gut microbiota interact.

The effect of inbreeding on fluctuating asymmetry of wing veins in two laboratory strains of [START]Drosophila melanogaster[END]. Many authors have proposed that inbreeding destabilizes developmental processes. This destabilization may be reflected by increased fluctuating asymmetry (FA) in inbred compared to relatively outbred populations, but many studies have failed to find such differences. We measured the left and right wings of a large number of individual [START]Drosophila melanogaster[END] from two genetically distinct populations to estimate changes in FA caused by inbreeding. The large sample size and experimental design allowed removal of potentially confounding directional asymmetry (DA) and measurement error terms. Trait means in the two populations were essentially unchanged by inbreeding (less than 0.5% smaller in both populations). Inbred lines showed higher signed FA variances (16 and 38% higher, significantly so in one population) and higher unsigned FA means (3.7 and 13.2%, significantly increased in one population). Significant DA was found in both populations, although the pattern differed between populations. DA did not change due to inbreeding.

Innate preference in [START]Drosophila melanogaster[END]. Innate preference behaviors are fundamental for animal survival. They actually form the basis for many animal complex behaviors. Recent years have seen significant progresses in disclosing the molecular and neural mechanism underlying animal innate preferences, especially in [START]Drosophila[END]. In this review, I will review these studies according to the sensory modalities adopted for preference assaying, such as vision, olfaction, thermal sensation. The behavioral strategies and the theoretic models for the formation of innate preferences are also reviewed and discussed.

The immune response of [START]Drosophila melanogaster[END]. The response of the [START]fruit fly[END] [START]Drosophila melanogaster[END] to various microorganism infections relies on a multilayered defense. The epithelia constitute a first and efficient barrier. Innate immunity is activated when microorganisms succeed in entering the body cavity of the fly. Invading microorganisms are killed by the combined action of cellular and humoral processes. They are phagocytosed by specialized blood cells, surrounded by toxic melanin, or lysed by antibacterial peptides secreted into the hemolymph by fat body cells. During the last few years, research has focused on the mechanisms of microbial recognition by various pattern recognition receptors and of the subsequent induction of antimicrobial peptide expression. The cellular arm of the [START]Drosophila[END] innate immune system, which was somehow neglected, now constitutes the new frontier.

Chemical communication in insects: the peripheral odour coding system of [START]Drosophila melanogaster[END]. Animals use their chemosensory systems to detect and discriminate among chemical cues in the environment. Remarkable progress has recently been made in our knowledge of the molecular and cellular basis of chemosensory perception in insects, based largely on studies in the vinegar fly [START]Drosophila melanogaster[END]. This progress has been possible due to the identification of gene families for olfactory receptors, the use of electro-physiological recording techniques on sensory neurons, the manifold of genetic manipulations that are available in this species and insights from several insect model systems. The superfamilies of olfactory receptor proteins, the Or genes and the more recently discovered IR genes, represent the essential elements in olfactory coding, endowing olfactory receptor neurons with their abilities to respond to specific sets of odorants or pheromones. General odorants activate receptors in a combinatorial fashion, but some receptors are narrowly tuned to pheromones or to carbon dioxide. Surprisingly, olfactory receptors in insects are biochemically quite different to those in mammals and do not appear to signal via classical G protein pathways but rather via ionotropic mechanisms. Here we review the past decade of intensive research since the discovery of the first insect olfactory receptors in 1999, focusing on the molecules and cells that underly peripheral olfactory perception in [START]Drosophila[END].

The regulation of organ size in [START]Drosophila[END]: physiology, plasticity, patterning and physical force. The correct regulation of organ size is a fundamental developmental process, the failure of which can compromise organ function and organismal integrity. Consequently, the mechanisms that regulate organ size have been subject to intense research. This research has highlighted four classes of mechanism that are involved in organ size regulation: physiology, plasticity, patterning and physical force. Nevertheless, how these mechanisms are integrated and converge on the cellular process that regulate organ growth is unknown. One group of animals where this integration is beginning to be achieved is in the insects. Here, I review the different mechanisms that regulate organ size in insects, and describe our current understanding of how these mechanisms interact. The genes and hormones involved are remarkably conserved in all animals, so these studies in insects provide a precedent for future research on organ size regulation in mammals.

Fruit flies for anti-pain drug discovery. Recent work has indicated that [START]fruit flies[END] ([START]Drosophila melanogaster[END]) can be used in nociception research. Genetic screening identified a gene, painless, that is required for thermal and mechanical nociception in [START]Drosophila[END] larvae. On the other hand, pharmacological techniques and noxious heat were used to assay antinocieceptive behavior in intact adult [START]Drosophila[END]. In general, animal models for pain research are bound by ethical concerns. Since no serious ethical controversies have been raised regarding experiments in insects, [START]Drosophila[END] may be, for the time being an ethically acceptable animal model for combined genetic and pharmacological analgesia research.

Transcriptional effects of a positive feedback circuit in [START]Drosophila melanogaster[END]. BACKGROUND: Synthetic systems that use positive feedback have been developed to control human disease vectors and crop pests. The tTAV system, which has been deployed in several insect species, relies on a positive feedback circuit that can be inhibited via dietary tetracycline. Although insects carrying tTAV fail to survive until adulthood in the absence of tetracycline, the exact reason for its lethality, as well as the transcriptomic effects of an active positive feedback circuit, remain unknown. RESULTS: We engineered the tTAV system in [START]Drosophila melanogaster[END] and investigated the effects of tTAV genome integration locus on the whole fly transcriptome during larval and adult life stages in four transgenic fly strains using gene expression microarrays. We found that while there were widespread effects on the transcriptome, the gene expression differences after removal of tetracycline were not consistent between integration sites. No specific region of the genome was affected, no common set of genes or pathways, nor did the integration site affect the transcripts in cis. CONCLUSION: Although the positive feedback tTAV system is effective at killing insect larvae regardless of where it is inserted in the genome, it does not exhibit a specific, consistent transcriptional signature. Instead, each insertion site is associated with broad, but different, transcriptional effects. Our results suggest that lethality may not be caused by a direct effect on transcription of a set of key genes or pathways. Instead, we propose that rather than a specific action of a tTAV protein, it is the stochastic transcriptional effects specific to each insertion site that contribute to the tTAV-induced mortality.

Physiological Maturation Lags Behind Behavioral Maturation in Newly Eclosed [START]Drosophila melanogaster[END] Males. The accessory gland (AG) produces seminal fluid proteins that are transferred to the female upon mating in many insects. These seminal fluid proteins often promote a male's post-copulatory reproductive success. Despite its crucial function many males eclose with a small gland not yet containing the full set of proteins. Thus, they need a physiological maturation period. Using [START]Drosophila melanogaster[END], we tested whether this physiological maturation is linked to behavioral maturation in males and to what extent seminal fluid allocation patterns are influenced by physiological maturation. To that end, we measured AG protein content (as a proxy for physiological maturation) of young, immature males that were either successful in gaining a mating, but prevented from transferring seminal fluid proteins, or unsuccessful, thus using mating success as a proxy for behavioral maturation. Furthermore, we compared ejaculate allocation in immature and mature males in a single mating. Though mating success and gland maturation increase with male age, we found no evidence for a fine-tuned synchronization of behavioral and physiological maturation in males. This is especially surprising since we found reduced ejaculate allocation in very young, immature males, hinting at reduced fitness benefits from early matings in [START]D. melanogaster[END].

Visuomotor control: [START]Drosophila[END] bridges the gap. [START]Fruit flies[END] with genetic lesions disrupting the structure of a brain region known as the protocerebral bridge fail to aim their movements correctly when crossing gaps, implicating this central brain neuropile in the visual control of goal-directed behaviour.

External control of the [START]Drosophila melanogaster[END] lifespan by combination of 3D oscillating low-frequency electric and magnetic fields. We demonstrate that the lifespan of [START]Drosophila melanogaster[END] population is controllable by a combination of external three-dimensional oscillating low-frequency electric and magnetic fields (3D OLFEMFs). The lifespan was decreased or increased in dependence of the parameters of the external 3D OLFEMFs. We propose that metabolic processes in [START]D. melanogaster[END]'s body are either accelerated (in the case of reduced lifespan) or slowed down (in the case of increased lifespan) in function of 3D OLFEMFs that induce vibrational motions on sub-cellular and larger scales.

Nitric oxide and [START]Drosophila[END] development. Mechanisms controlling the transition of precursor cells from proliferation to differentiation during organism development determine the distinct anatomical features of tissues and organs. NO may mediate such a transition since it can suppress DNA synthesis and cell proliferation. Inhibition of NOS activity in the imaginal discs of [START]Drosophila[END] larvae results in hypertrophy of tissues and organs of the adult fly, whereas ectopic overexpression of NOS has the reciprocal, hypotrophic, effect. Furthermore, NO production is crucial for the establishment of ordered neuronal connections in the visual system of the fly, indicating that NO affects the acquisition of the differentiated phenotype by the neural tissue. Increasing evidence points to a broad role that NO may play in animal development by acting as an essential negative regulator of precursor cell proliferation during tissue and organ morphogenesis.

[START]Drosophila melanogaster[END]: a model organism for controlling Dipteran vectors and pests. Beta-carbonic anhydrases (beta-CAs) have been recently reported to be present in many protozoan and metazoan species, whereas it is absent in mammals. In this review, we introduce beta-CA from [START]Drosophila melanogaster[END] as a model enzyme for pesticide development. These enzymes can be targeted with various enzyme inhibitors, which can have deleterious effects on pathogenic and other harmful organisms. Therefore, beta-CAs represent a new potential target to fight against Dipteran vectors and pests relevant to medicine, veterinary medicine, and agriculture.

Turning food into eggs: insights from nutritional biology and developmental physiology of [START]Drosophila[END]. Nutrition plays a central role in fecundity, regulating the onset of reproductive maturity, egg production, and the survival and health of offspring from insects to humans. Although decades of research have worked to uncover how nutrition mediates these effects, it has proven difficult to disentangle the relative role of nutrients as the raw material for egg and offspring development versus their role in stimulating endocrine cascades necessary to drive development. This has been further complicated by the fact that both nutrients and the signalling cascades they regulate interact in complex ways to control fecundity. Separating the two effects becomes important when trying to understand how fecundity is regulated, and in devising strategies to offset the negative effects of nutrition on reproductive health. In this review, we use the extensive literature on egg development in the [START]fruit fly[END] [START]Drosophila melanogaster[END] to explore how the nutrients from food provide the building blocks and stimulate signalling cascades necessary for making an egg.

[START]Drosophila[END] immune cell migration and adhesion during embryonic development and larval immune responses. The majority of immune cells in [START]Drosophila melanogaster[END] are plasmatocytes; they carry out similar functions to vertebrate macrophages, influencing development as well as protecting against infection and cancer. Plasmatocytes, sometimes referred to with the broader term of hemocytes, migrate widely during embryonic development and cycle in the larvae between sessile and circulating positions. Here we discuss the similarities of plasmatocyte developmental migration and its functions to that of vertebrate macrophages, considering the recent controversy regarding the functions of [START]Drosophila[END] PDGF/VEGF related ligands. We also examine recent findings on the significance of adhesion for plasmatocyte migration in the embryo, as well as proliferation, trans-differentiation, and tumor responses in the larva. We spotlight parallels throughout to vertebrate immune responses.

Dynamic changes in ejaculatory bulb size during [START]Drosophila melanogaster[END] aging and mating. The ejaculatory bulb of [START]Drosophila melanogaster[END] males produces proteins and pheromones that play important roles in reproduction. This tissue is also the final mixing site for the ejaculate before transfer to the female. The ejaculatory bulb's dynamics remain largely unstudied. By microscopy of the ejaculatory bulb in maturing adult males, we observed that the ejaculatory bulb expands in size as males age. Moreover, we document that when males mate, their ejaculatory bulb expands further as ejaculate transfer begins, and then contracts halfway through the course of mating as ejaculate transfer finishes. Although there is some male-to-male variation in the timing of these changes, ultimately the tissue changes in a predictable pattern that gives insight into the active mating process in [START]Drosophila[END].

A genetic and developmental analysis of mutations in the Deformed locus in [START]Drosophila melanogaster[END]. Individuals expressing recessive mutations in the Deformed (Dfd) locus of [START]Drosophila melanogaster[END] were examined for embryonic and adult defects. Mutant embryos were examined in both scanning electron microscope and light microscope preparations. The adult Dfd recessive mutant phenotype was assessed in somatic clones and in survivors homozygous for hypomorphic alleles of the gene. The time of Dfd+ action was determined by studying a temperature conditional allele. Dfd+ is required in three embryonic cephalic segments to form a normal head. Mutant embryos of Dfd display defects in derivatives of the maxillary segment, of the mandibular segment, and of some more anterior segments. In the adult fly, defects are seen in the posterior aspect of the head when the gene is mutant. A transformation from head to thoracic-like tissue is seen dorsally and a deletion of structures is seen ventrally. Shift studies utilizing a temperature conditional allele have shown that the gene product is necessary during at least two periods of development, during embryonic segmentation and head involution and during the late larval and pupal stages. From these studies we conclude that Dfd is a homeotic gene necessary for proper specification of both the embryonic and the adult head.

A comparison of the transcriptome of [START]Drosophila melanogaster[END] in response to entomopathogenic fungus, ionizing radiation, starvation and cold shock. BACKGROUND: The molecular mechanisms that determine the organism's response to a variety of doses and modalities of stress factors are not well understood. RESULTS: We studied effects of ionizing radiation (144, 360 and 864 Gy), entomopathogenic fungus (10 and 100 CFU), starvation (16 h), and cold shock (+4, 0 and -4 C) on an organism's viability indicators (survival and locomotor activity) and transcriptome changes in the [START]Drosophila melanogaster[END] model. All stress factors but cold shock resulted in a decrease of lifespan proportional to the dose of treatment. However, stress-factors affected locomotor activity without correlation with lifespan. Our data revealed both significant similarities and differences in differential gene expression and the activity of biological processes under the influence of stress factors. CONCLUSIONS: Studied doses of stress treatments deleteriously affect the organism's viability and lead to different changes of both general and specific cellular stress response mechanisms.

Care and feeding of [START]Drosophila melanogaster[END]. The information provided here should allow you to begin working with [START]Drosophila[END]. Mine your colleagues for alternative approaches, improvements, and refinements and develop your own. If you find a new and better way to do any aspect of fly work, take the time to share it with your colleagues through bionet.[START]drosophila[END] or DIN.

Male-Killing Spiroplasma Alters Behavior of the Dosage Compensation Complex during [START]Drosophila melanogaster[END] Embryogenesis. Numerous arthropods harbor maternally transmitted bacteria that induce the preferential death of males [1-7]. This sex-specific lethality benefits the bacteria because males are "dead ends" regarding bacterial transmission, and their absence may result in additional resources for their viable female siblings who can thereby more successfully transmit the bacteria [5]. Although these symbionts disrupt a range of developmental processes [8-10], the underlying cellular mechanisms are largely unknown. It was previously shown that mutations in genes of the dosage compensation pathway of [START]Drosophila melanogaster[END] suppressed male killing caused by the bacterium, Spiroplasma [10]. This result suggested that dosage compensation is a target of Spiroplasma. However, it remains unclear how this pathway is affected, and whether the underlying interactions require the male-specific cellular environment. Here, we investigated the cellular basis of male embryonic lethality in [START]D. melanogaster[END] induced by Spiroplasma. We found that the dosage compensation complex (DCC), which acetylates X chromatin in males [11], becomes mis-localized to ectopic regions of the nucleus immediately prior to the killing phase. This effect was accompanied by inappropriate histone acetylation and genome-wide mis-regulation of gene expression. Artificially induced formation of the DCC in infected females, through transgenic expression of the DCC-specific gene msl-2, resulted in mis-localization of this complex to non-X regions and early Spiroplasma-induced death, mirroring the killing effects in males. These findings strongly suggest that Spiroplasma initiates male killing by targeting the dosage compensation machinery directly and independently of other cellular features characteristic of the male sex.

Neuronal homeostasis through translational control. Translational repression is a key component of the mechanism that establishes segment polarity during early embryonic development in the fruitfly [START]Drosophila melanogaster[END]. Two proteins, Pumilio (Pum) and Nanos, block the translation of hunchback messenger RNA in only the posterior segments, thereby promoting an abdominal fate. More recent studies focusing on postembryonic neuronal function have shown that Pum is also integral to numerous mechanisms that allow neurons to adapt to the changing requirements placed on them in a dynamic nervous system. These mechanisms include those contributing to dendritic structure, synaptic growth, neuronal excitability, and formation of long-term memory. This article describes these new studies and highlights the role of translational repression in regulation of neuronal processes that compensate for change.

The role of commensal microbes in the lifespan of [START]Drosophila melanogaster[END]. Commensal microbes have mutualistic relationships with their host and mainly live in the host intestine. There are many studies on the relationships between commensal microbes and host physiology. However, there are inconsistent results on the effects of commensal microbes on host lifespan. To clarify this controversy, we generated axenic flies by using two controlled methods - bleaching and antibiotic treatment - and investigated the relationship between the commensal microbes and host lifespan in [START]Drosophila melanogaster[END]. The removal of microbes by using bleaching and antibiotic treatments without detrimental effects increased fly lifespan. Furthermore, a strain of flies colonized with a high load of microbiota showed a greater effect on lifespan extension when the microbes were eliminated, suggesting that commensal bacteria abundance may be a critical determinant of host lifespan. Consistent with those observations, microbial flora of aged fly gut significantly decreased axenic fly lifespan via an increase in bacterial load rather than through a change of bacterial composition. Our elaborately controlled experiments showed that the elimination of commensal microbes without detrimental side effects increased fly lifespan, and that bacterial load was a significant determinant of lifespan. Furthermore, our results indicate the presence of a deterministic connection between commensal microbes and host lifespan.

The relationship between the functional complexity and the molecular organization of the Antennapedia locus of [START]Drosophila melanogaster[END]. The Antp locus is involved in the development of the thorax of the larval and adult [START]Drosophila[END]. The absence of Antp+ function during embryogenesis results in the larval mesothorax exhibiting characteristics of the prothorax and an ensuing lethality; the loss of Antp+ function in the development of the adult thorax causes specific portions of the leg, wing and humeral imaginal discs to develop abnormally. Every Antp mutation, however, does not cause all of these developmental defects. Certain mutant alleles disrupt humeral and wing disc development without affecting leg development, and they are not deficient for the wild-type function required during embryogenesis. Other Antp mutations result in abnormal legs, but do not alter dorsal thoracic development. Mutations of each type can complement to produce a normal adult fly, which suggests that there are at least two discrete functional units within the locus. This hypothesis is supported by the fact that each of the developmental defects arises from the alteration of a different physical region within the Antp DNA. These observations indicate that the complete developmental role of the Antp locus is defined by the spatial and temporal regulation of the expression of several individual functional units.

Genetic variability of the interpulse interval of courtship song among some European populations of [START]Drosophila melanogaster[END]. The interpulse interval of the courtship song of [START]Drosophila melanogaster[END] is a character which may play a significant role in mating success and reproductive isolation. Here we examine the variability of interpulse interval among replicated laboratory strains of [START]D. melanogaster[END]. There is no significant variation among populations of different geographical origin. This suggests that interpulse interval is subject to strong selection, as the populations are known to differ for other characters. One population, however, was sufficiently different to allow a genetic analysis. Reciprocal F1s and backcrosses implied that the variance was predominantly additive and autosomal. Possible sources of selection on interpulse interval are discussed.

Selection for circadian eclosion time in [START]Drosophila melanogaster[END]. Early and late eclosion strains were developed from [START]Drosophila melanogaster[END] cultures. The Oregon-R parent strains (isolated in 1925) showed significantly more selectability than the W(2) parent strain collected at the beginning of this study (1971). This is consistent with the hypothesis that the selective advantage of circadian behaviors is reduced in laboratory conditions.

Identification and characterization of the major [START]Drosophila melanogaster[END] mating plug protein. In many insects, semen coagulates into a mating plug at the distal part of the female's genital tract. Mating plugs have been proposed to facilitate sperm movement or to prevent subsequent matings or sperm loss. The molecular constituents of insect mating plugs have not previously been characterized. Here we report that an abundant autofluorescent protein made by the [START]Drosophila melanogaster[END] male's ejaculatory bulb is a major constituent of the posterior region of the mating plug. Identities in size, chromosomal location and expression pattern indicate that the autofluorescent protein is PEB-me, an abundant ejaculatory bulb protein reported by Ludwig et al. [Biochem. Genet. 29 (1991) 215]. We cloned and sequenced the RNA encoding this protein. The transcript, which is male-specific and expressed only in the ejaculatory bulb, encodes a 377 a.a. predicted secreted protein with PGG repeats similar to those in homopolymer-forming proteins found in spider silk.

Setting the clock--by nature: circadian rhythm in the fruitfly [START]Drosophila melanogaster[END]. Nowadays humans mainly rely on external, unnatural clocks such as of cell phones and alarm clocks--driven by circuit boards and electricity. Nevertheless, our body is under the control of another timer firmly anchored in our genes. This evolutionary very old biological clock drives most of our physiology and behavior. The genes that control our internal clock are conserved among most living beings. One organism that shares this ancient clock mechanism with us humans is the fruitfly [START]Drosophila melanogaster[END]. Since it turned out that [START]Drosophila[END] is an excellent model, it is no surprise that its clock is very well and intensely investigated. In the following review we want to display an overview of the current understanding of [START]Drosophila[END]'s circadian clock.

Odour avoidance learning in the larva of [START]Drosophila melanogaster[END]. [START]Drosophila[END] larvae can be trained to avoid odours associated with electric shock. We describe here, an improved method of aversive conditioning and a procedure for decomposing learning retention curve that enables us to do a quantitative analysis of memory phases, short term (STM), middle term (MTM) and long term (LTM) as a function of training cycles. The same method of analysis when applied to learning mutants dunce, amnesiac, rutabaga and radish reveals memory deficits characteristic of the mutant strains.

Female and male genetic contributions to post-mating immune defence in female [START]Drosophila melanogaster[END]. Post-mating reduction in immune defence is common in female insects, and a trade-off between mating and immunity could affect the evolution of immunity. In this work, we tested the capacity of virgin and mated female [START]Drosophila melanogaster[END] to defend against infection by four bacterial pathogens. We found that female [START]D. melanogaster[END] suffer post-mating immunosuppression in a pathogen-dependent manner. The effect of mating was seen after infection with two bacterial pathogens (Providencia rettgeri and Providencia alcalifaciens), though not after infection with two other bacteria (Enterococcus faecalis and Pseudomonas aeruginosa). We then asked whether the evolution of post-mating immunosuppression is primarily a 'female' or 'male' trait by assaying for genetic variation among females for the degree of post-mating immune suppression they experience and among males for the level of post-mating immunosuppression they elicit in their mates. We also assayed for an interaction between male and female genotypes to test the specific hypothesis that the evolution of a trade-off between mating and immune defence in females might be being driven by sexual conflict. We found that females, but not males, harbour significant genetic variation for post-mating immunosuppression, and we did not detect an interaction between female and male genotypes. We thus conclude that post-mating immune depression is predominantly a 'female' trait, and find no evidence that it is evolving under sexual conflict.

Insulin signalling mediates the response to male-induced harm in female [START]Drosophila melanogaster[END]. Genetic manipulations in nutrient-sensing pathways are known to both extend lifespan and modify responses to environmental stressors (e.g., starvation, oxidative and thermal stresses), suggesting that similar mechanisms regulate lifespan and stress resistance. However, despite being a key factor reducing female lifespan and affecting female fitness, male-induced harm has rarely been considered as a stressor mediated by nutrient sensing pathways. We explored whether a lifespan-extending manipulation also modifies female resistance to male-induced harm. To do so, we used long-lived female [START]Drosophila melanogaster[END] that had their insulin signalling pathway downregulated by genetically ablating the median neurosecretory cells (mNSC). We varied the level of exposure to males for control and ablated females and tested for interacting effects on female lifespan and fitness. As expected, we found that lifespan significantly declined with exposure to males. However, mNSC-ablated females maintained significantly increased lifespan across all male exposure treatments. Furthermore, lifespan extension and relative fitness of mNSC-ablated females were maximized under intermediate exposure to males, and minimized under low and high exposure to males. Overall, our results suggest that wild-type levels of insulin signalling reduce female susceptibility to male-induced harm under intense sexual conflict, and may also protect females when mating opportunities are sub-optimally low.

Sensitivity to ether anesthesia and to gamma-rays in mutagen-sensitive strains of [START]Drosophila melanogaster[END]. An ether-resistant strain of [START]Drosophila melanogaster[END], Eth-29, has previously been found to be radiosensitive. Some mutagen-sensitive strains are known to be hypersensitive to X-rays in larvae. The correlation between sensitivities to ether anesthesia and to gamma-rays was examined in adult flies of 12 mutagen-sensitive strains and 6 control strains. A wide variation in sensitivities to ether anesthesia, gamma-ray knock-down and gamma-ray lethality was demonstrated. No correlation between DNA-repair capacity and ether sensitivity or gamma-ray knock-down sensitivity was shown. Only mei-9 and mus201, which are deficient in excision repair, as well as Eth-29 were found to be sensitive to gamma-ray lethality. These findings indicate that the targets for ether anesthesia, knock-down and lethality may be different. Lethality appears to be caused by DNA damage, while the other 2 endpoints appear not to be related to DNA damage.

Binucleation of Accessory Gland Lobe Contributes to Effective Ejection of Seminal Fluid in [START]Drosophila melanogaster[END]. The adult male accessory gland in insects is an internal reproductive organ analogous to the mammalian prostate, and secretes various components in the seminal fluid. Products of the accessory gland in the [START]fruit fly[END] [START]Drosophila melanogaster[END] are known to control reproductive behaviors in mated females, such as food uptake, oviposition rate, and rejection of re-mating with other males, all of which increase male reproductive capacity. Production of larger amounts of accessory gland products is thus thought to result in higher male reproductive success. The epithelium of the [START]Drosophila[END] accessory gland lobe is composed of a unique population of binucleate cells. We previously predicted, based on measurements of cell size in mono/binucleate mosaic accessory glands, that binucleation results in a higher plasticity in cell shape, enabling more effective ejection of seminal fluid. However, the actual effect of binucleation on ejection of seminal fluid or reproductive capacity remained unclear, as we were unable to generate an organ with uniformly mononucleate cells. In the present study, we generated organs in which most of the epithelial cells are mononucleate by manipulating aurora B or fizzy-related to block binucleation. Mononucleation resulted in a less elastic accessory gland lobe, which decreased ejection volume and the oviposition of mated females; these effects were particularly pronounced over the long term. These results suggest that binucleation in accessory gland epithelial cells contributes to higher plasticity in the volume of this organ, and enhances male reproductive success through enabling ejection of larger amounts of seminal fluid.

Spatial and temporal expression of the period gene in [START]Drosophila melanogaster[END]. The temporal and spatial expression of the period gene of [START]Drosophila melanogaster[END] has been analyzed by examining the expression of a per beta-galactosidase fusion gene in transformants and by in situ hybridization experiments with wild-type flies. Several strains of [START]Drosophila melanogaster[END], transformed with the fusion gene, have been generated. The gene is active in mid-late embryos in the midline of the nervous system. Thereafter, beta-galactosidase activity is undetectable until the pupal stage when the prothoracic gland-corpora allata and the optic lobes are beta-galactosidase positive. In adults a surprisingly large number of tissues stain positively, including antennae, proboscis, eyes, optic lobes, cells of the central brain, cells of the thoracic ganglia, gut, Malpighian tubules, and ovarian follicle cells. The temporal pattern of expression agrees well with previous estimates made from developmental Northern blots with RNA extracted from wild-type animals. We suggest that many of the tissues that express the per gene contain their own intrinsic oscillator activity.

Deleterious mutations show increasing negative effects with age in [START]Drosophila melanogaster[END]. BACKGROUND: In order for aging to evolve in response to a declining strength of selection with age, a genetic architecture that allows for mutations with age-specific effects on organismal performance is required. Our understanding of how selective effects of individual mutations are distributed across ages is however poor. Established evolutionary theories assume that mutations causing aging have negative late-life effects, coupled to either positive or neutral effects early in life. New theory now suggests evolution of aging may also result from deleterious mutations with increasing negative effects with age, a possibility that has not yet been empirically explored. RESULTS: To directly test how the effects of deleterious mutations are distributed across ages, we separately measure age-specific effects on fecundity for each of 20 mutations in [START]Drosophila melanogaster[END]. We find that deleterious mutations in general have a negative effect that increases with age and that the rate of increase depends on how deleterious a mutation is early in life. CONCLUSIONS: Our findings suggest that aging does not exclusively depend on genetic variants assumed by the established evolutionary theories of aging. Instead, aging can result from deleterious mutations with negative effects that amplify with age. If increasing negative effect with age is a general property of deleterious mutations, the proportion of mutations with the capacity to contribute towards aging may be considerably larger than previously believed.

Neuropeptide Mapping of Dimmed Cells of Adult [START]Drosophila[END] Brain. Neuropeptides are structurally highly diverse messenger molecules that act as regulators of many physiological processes such as development, metabolism, reproduction or behavior in general. Differentiation of neuropeptidergic cells often corresponds with the presence of the transcription factor DIMMED. In the central nervous system of the [START]fruit fly[END] [START]Drosophila melanogaster[END], DIMMED commonly occurs in neuroendocrine neurons that release peptides as neurohormones but also in interneurons with complex branching patterns. Fly strains with green fluorescence protein (GFP)-expressing dimmed cells make it possible to systematically analyze the processed neuropeptides in these cells. In this study, we mapped individual GFP-expressing neurons of adult [START]D. melanogaster[END] from the dimmed (c929)>GFP line. Using single cell mass spectrometry, we analyzed 10 types of dimmed neurons from the brain/gnathal ganglion. These cells included neuroendocrine cells with projection into the retrocerebral complex but also a number of large interneurons. Resulting mass spectra not only provided comprehensive data regarding mature products from 13 neuropeptide precursors but also evidence for the cellular co-localization of neuropeptides from different neuropeptide genes. The results can be implemented in a neuroanatomical map of the [START]D. melanogaster[END] brain. Graphical Abstract .

Conjugated Linoleic Acid Regulates Body Composition and Locomotor Activity in a Sex-Dependent Manner in [START]Drosophila melanogaster[END]. Conjugated linoleic acid (CLA) has been reported to be a bioactive food component. However, there is limited knowledge on the sex-dependent effects of CLA on energy metabolism. In the present study, [START]Drosophila melanogaster[END] was used to investigate the sex-dependent effects of CLA with respect to body fat, muscle, locomotion, and a key metabolic regulator, AMP-activated protein kinase alpha (AMPKalpha). Adult flies were fed a cornmeal-based fly food with 0.5% of CLA oil (50:50 of cis-9,trans-11 and trans-10,cis-12 CLA isomers in triacylglycerol (TAG) form), 0.5% safflower oil (high in linoleic acid [LNA] as control), or 0.5% water (as blank) for 5 days. Accumulation of CLA in tissue was verified using gas chromatography-mass spectrometry. CLA-fed flies had reduced TAG and increased locomotor activity when compared to LNA-fed control flies. In addition, CLA increased the muscle content when compared to the blank. Moreover, following CLA supplementation, increased AMPKalpha activity was observed in females, but not in males. These sex-dependent metabolic effects of CLA may be due to physiological differences in lipid metabolism and nutrient requirements. In conclusion, CLA promoted the body composition and locomotion behavior in [START]D. melanogaster[END] and regulated the sex-specific metabolism in part via AMPKalpha. As key physiological processes are conserved between fly and human, information obtained from this research could provide valuable insights into sex-dependent responses to CLA in humans.

Target genes of homeodomain proteins. Homeodomain proteins are transcription factors that share a related DNA binding domain, the homeodomain. This class of proteins was first recognized in the fruitfly [START]Drosophila melanogaster[END] where they cause homeotic transformations such as a fly with four wings instead of two (Lewis EB. A gene complex controlling segmentation in [START]Drosophila[END]. Nature 1978;276:565-570 [Ref. 18]). They are now known to exist in all eukaryotes where they perform important functions during development. Given that homeodomain proteins are transcription factors, they control the expression of downstream genes to regulate development. Which genes are controlled by homeodomain proteins and how many of them are there? This review focuses on a recent paper by Liang and Biggin (Liang Z, Biggin MD. Eve and Ftz regulate a wide array of genes in blastoderm embryos: the selector homeoproteins directly or indirectly regulate most genes in [START]Drosophila[END]. Development 1998; 125:4471-4482 [Ref. 1]), which proposes that the [START]Drosophila[END] homeodomain proteins Even-skipped and Fushi-tarazu directly control the expression of the majority of genes in the [START]Drosophila[END] genome. An alternative view, that most genes are only indirectly affected by homeodomain proteins is also discussed.

Physiological and metabolic consequences of viral infection in [START]Drosophila melanogaster[END]. An extensively used model system for investigating anti-pathogen defence and innate immunity involves Drosophila C virus (DCV) and [START]Drosophila melanogaster[END]. While there has been a significant effort to understand infection consequences at molecular and genetic levels, an understanding of fundamental higher-level physiology of this system is lacking. Here, we investigate the metabolic rate, locomotory activity, dry mass and water content of adult male flies injected with DCV, measured over the 4 days prior to virus-induced mortality. DCV infection resulted in multiple pathologies, notably the depression of metabolic rate beginning 2 days post-infection as a response to physiological stress. Even in this depressed metabolic state, infected flies did not decrease their activity until 1 day prior to mortality, which further suggests that cellular processes and synthesis are disrupted because of viral infection. Growth rate was also reduced, indicating that energy partitioning is altered as infection progresses. Microbial infection in insects typically results in an increase in excretion; however, water appeared to be retained in DCV-infected flies. We hypothesise that this is due to a fluid intake-output imbalance due to disrupted transport signalling and a reduced rate of metabolic processing. Furthermore, infected flies had a reduced rate of respiration as a consequence of metabolic depression, which minimised water loss, and the excess mass as a result of water retention is concurrent with impaired locomotory ability. These findings contribute to developing a mechanistic understanding of how pathologies accumulate and lead to mortality in infected flies.

[Development of [START]Drosophila melanogaster[END] in space flight]. The review deals with the available literary data on different aspects of [START]Drosophila melanogaster[END] vital functions in the conditions of real and modeled microgravity. The developmental stages, embryogenesis and aging, specifically, and behavioral reactions are discussed. The presented results of morphological as well as molecular genetic analyses are indicative of structural changes in early [START]Drosophila[END] embryos and their compensation during subsequent development, and formation of an adaptive gene-expression pattern in microgravity.

There and back again: The mechanisms of differentiation and transdifferentiation in [START]Drosophila[END] blood cells. Transdifferentiation is a conversion of an already differentiated cell type into another cell type without the involvement of stem cells. This transition is well described in the case of vertebrate immune cells, as well as in [START]Drosophila melanogaster[END], which therefore serves as a suitable model to study the process in detail. In the [START]Drosophila[END] larva, the latest single-cell sequencing methods enabled the clusterization of the phagocytic blood cells, the plasmatocytes, which are capable of transdifferentiation into encapsulating cells, the lamellocytes. Here we summarize the available data of the past years on the plasmatocyte-lamellocyte transition, and make an attempt to harmonize them with transcriptome-based blood cell clustering to better understand the underlying mechanisms of transdifferentiation in [START]Drosophila[END], and in general.

Genome-wide analysis of genes associated with moderate and high DDT resistance in [START]Drosophila melanogaster[END]. BACKGROUND: Moderate to high DDT resistance in generally associated with overexpression of multiple genes and therefore has been considered to be polygenic. However, very little information is available about the molecular mechanisms that insect populations employ when evolving increased levels of resistance. The presence of common regulatory motifs among resistance-associated genes may help to explain how and why certain suites of genes are preferentially represented in genomic-scale analyses. RESULTS: A set of commonly differentially expressed genes associated with DDT resistance in the [START]fruit fly[END] was identified on the basis of genome-wide microarray analysis followed by qRT-PCR verification. More genes were observed to be overtranscribed in the highly resistant strain (91-R) than in the moderately resistant strain (Wisconsin) and susceptible strain (Canton-S). Furthermore, possible transcription factor binding sites that occurred in coexpressed resistance-associated genes were discovered by computational motif discovery methods. CONCLUSION: A glucocorticoid receptor (GR)-like putative transcription factor binding motif (TFBM) was observed to be associated with genes commonly differentially transcribed in both the 91-R and Wisconsin lines of DDT-resistant [START]Drosophila[END].

Estimating the heritability of female lifetime fecundity in a locally adapted [START]Drosophila melanogaster[END] population. The heritability of genome-wide fitness that is expected in finite populations is poorly understood, both theoretically and empirically, despite its relevance to many fundamental concepts in evolutionary biology. In this study, we used two independent methods of estimating the heritability of lifetime female fecundity (the predominant female fitness component in this population) in a large, outbred population of [START]Drosophila melanogaster[END] that had adapted to the laboratory environment for over 400 generations. Despite strong directional selection on adult female fecundity, we uncovered high heritability for this trait that cannot be explained by antagonistic pleiotropy with juvenile fitness. The evolutionary significance of this high heritability of lifetime fecundity is discussed.

Large-scale selective sweep among Segregation Distorter chromosomes in African populations of [START]Drosophila melanogaster[END]. Segregation Distorter (SD) is a selfish, coadapted gene complex on chromosome 2 of [START]Drosophila melanogaster[END] that strongly distorts Mendelian transmission; heterozygous SD/SD(+) males sire almost exclusively SD-bearing progeny. Fifty years of genetic, molecular, and theory work have made SD one of the best-characterized meiotic drive systems, but surprisingly the details of its evolutionary origins and population dynamics remain unclear. Earlier analyses suggested that the SD system arose recently in the Mediterranean basin and then spread to a low, stable equilibrium frequency (1-5%) in most natural populations worldwide. In this report, we show, first, that SD chromosomes occur in populations in sub-Saharan Africa, the ancestral range of [START]D. melanogaster[END], at a similarly low frequency (approximately 2%), providing evidence for the robustness of its equilibrium frequency but raising doubts about the Mediterranean-origins hypothesis. Second, our genetic analyses reveal two kinds of SD chromosomes in Africa: inversion-free SD chromosomes with little or no transmission advantage; and an African-endemic inversion-bearing SD chromosome, SD-Mal, with a perfect transmission advantage. Third, our population genetic analyses show that SD-Mal chromosomes swept across the African continent very recently, causing linkage disequilibrium and an absence of variability over 39% of the length of the second chromosome. Thus, despite a seemingly stable equilibrium frequency, SD chromosomes continue to evolve, to compete with one another, or evade suppressors in the genome.

Context- and dose-dependent modulatory effects of naringenin on survival and development of [START]Drosophila melanogaster[END]. Naringenin, the predominant bioflavonoid found in grapefruit and tomato has diverse bioactive properties that encompass anti-carcinogenic, anti-inflammatory, anti-atherogenic, anti-estrogenic, anti-hyperlipidemic and anti-hyperglycemic characteristics. Naringenin has not been explored for its pro-longevity traits in [START]fruit flies[END]. Therefore, the current study explores its influence on longevity, fecundity, feeding rate, larval development, resistance to starvation stress and body weight in male and female wild-type [START]Drosophila melanogaster[END] Canton-S flies. Flies were fed with normal and high fat diets respectively. The results implied hormetic effects of naringenin on longevity and development in flies. In flies fed with standard and high fat diets, lower concentrations of naringenin (200 and 400 microM) augmented mean lifespan while higher concentrations (600 and 800 microM) were consistently lethal. However, enhanced longevity seen at 400 microM of naringenin was at the expense of reduced fecundity and food intake in flies. Larvae reared on standard diet having 200 microM of naringenin exhibited elevated pupation and emergence as flies. Eclosion time was hastened in larvae reared on standard diet having 200 microM of naringenin. Female flies fed with a standard diet having 200 and 400 microM of naringenin were more resistant to starvation stress. Reduction in body weight was observed in male and female flies fed with a high fat diet supplemented with 200 and 400 microM of naringenin respectively. Collectively, the results elucidated a context- and dose-dependent hormetic efficacy of naringenin that varied with gender, diet and stage of lifecycle in flies.

Variation in the male pheromones and mating success of wild caught [START]Drosophila melanogaster[END]. [START]Drosophila melanogaster[END] males express two primary cuticular hydrocarbons (male-predominant hydrocarbons). These act as sex pheromones by influencing female receptivity to mating. The relative quantities of these hydrocarbons vary widely among natural populations and can contribute to variation in mating success. We tested four isofemale lines collected from a wild population to assess the effect of intrapopulation variation in male-predominant hydrocarbons on mating success. The receptivity of laboratory females to males of the four wild-caught lines varied significantly, but not consistently in the direction predicted by variation in male-predominant hydrocarbons. Receptivity of the wild-caught females to laboratory males also varied significantly, but females from lines with male-predominant hydrocarbon profiles closer to a more cosmopolitan one did not show a correspondingly strong mating bias toward a cosmopolitan male. Among wild-caught lines, the male-specific ejaculatory bulb lipid, cis-vaccenyl acetate, varied more than two-fold, but was not associated with variation in male mating success. We observed a strong inverse relationship between the receptivity of wild-caught females and the mating success of males from their own lines, when tested with laboratory flies of the opposite sex.

Growth and size control during development. The size and shape of organs are characteristic for each species. Even when organisms develop to different sizes due to varying environmental conditions, such as nutrition, organ size follows species-specific rules of proportionality to the rest of the body, a phenomenon referred to as allometry. Therefore, for a given environment, organs stop growth at a predictable size set by the species's genotype. How do organs stop growth? How can related species give rise to organs of strikingly different size? No definitive answer has been given to date. One of the major models for the studies of growth termination is the vinegar fly [START]Drosophila melanogaster[END]. Therefore, this review will focus mostly on work carried out in [START]Drosophila[END] to try to tease apart potential mechanisms and identify routes for further investigation. One general rule, found across the animal kingdom, is that the rate of growth declines with developmental time. Therefore, answers to the problem of growth termination should explain this seemingly universal fact. In addition, growth termination is intimately related to the problems of robustness (i.e. precision) and plasticity in organ size, symmetric and asymmetric organ development, and of how the 'target' size depends on extrinsic, environmental factors.

Ecdysone control of developmental transitions: lessons from [START]Drosophila[END] research. The steroid hormone ecdysone is the central regulator of insect developmental transitions. Recent new advances in our understanding of ecdysone action have relied heavily on the application of [START]Drosophila melanogaster[END] molecular genetic tools to study insect metamorphosis. In this review, we focus on three major aspects of [START]Drosophila[END] ecdysone biology: (a) factors that regulate the timing of ecdysone release, (b) molecular basis of stage- and tissue-specific responses to ecdysone, and (c) feedback regulation and coordination of ecdysone signaling.

Acrylamide is genotoxic to the somatic and germ cells of [START]Drosophila melanogaster[END]. The genotoxic effects of acrylamide, a recently detected carcinogen, have been studied in the somatic (wing primordia) and germ cells of [START]Drosophila melanogaster[END] by the wing mosaic assay and the sex-linked recessive lethal test respectively. Larvae, 72 +/- 4 h old, were exposed to 6 different concentrations of acrylamide ranging between 0.25 mM and 5.0 mM in instant medium for 48 h. It is observed that acrylamide is both mutagenic and recombinogenic in the wing disc cells and induces sex-linked recessive lethals.

Conversion of the chill susceptible [START]fruit fly[END] larva ([START]Drosophila melanogaster[END]) to a freeze tolerant organism. Among vertebrates, only a few species of amphibians and reptiles tolerate the formation of ice crystals in their body fluids. Freeze tolerance is much more widespread in invertebrates, especially in overwintering insects. Evolutionary adaptations for freeze tolerance are considered to be highly complex. Here we show that surprisingly simple laboratory manipulations can change the chill susceptible insect to the freeze tolerant one. Larvae of [START]Drosophila melanogaster[END], a [START]fruit fly[END] of tropical origin with a weak innate capacity to tolerate mild chilling, can survive when approximately 50% of their body water freezes. To achieve this goal, synergy of two fundamental prerequisites is required: (i) shutdown of larval development by exposing larvae to low temperatures (dormancy) and (ii) incorporating the free amino acid proline in tissues by feeding larvae a proline-augmented diet (cryopreservation).

Measuring the fitness benefits of male mate choice in [START]Drosophila melanogaster[END]. It is increasingly realized that the potential for male mate choice is widespread across many taxa. However, measurements of the relative magnitude of the fitness benefits that such choice can confer are lacking. Here, we directly measured, in a comprehensive set of tests that manipulated key variables, the fitness benefits of male mate choice in [START]Drosophila melanogaster[END] by measuring egg production in females that were chosen or rejected by males. The results provided significant evidence for male mate choice. In absolute terms, the observed degree of choice increased male fitness by an average of only 1.59 eggs. However, using a novel technique we show that this benefit of choice represented 14.5% of the maximum potential fitness benefit of choice. The magnitude of mate choice was not significantly altered by variation in (1) mate compatibility, (2) phenotypic plasticity in male mate choice, or (3) whether choosing males were preferred or nonpreferred by females. Overall, we show that male mate choice represents a subtle but significant opportunity for sexual selection, and we offer a novel and widely applicable method for quantifying mate choice.

Radiation hormesis and radioadaptive response in [START]Drosophila melanogaster[END] flies with different genetic backgrounds: the role of cellular stress-resistance mechanisms. The purpose of this work is to investigate the role of cellular stress-resistance mechanisms in the low-dose irradiation effects on [START]Drosophila melanogaster[END] lifespan. In males and females with the wild type Canton-S genotype the chronic low dose irradiation (40 cGy) induced the hormetic effect and radiation adaptive response to acute irradiation (30 Gy). The hormesis and radioadaptive responses were observed in flies with mutations in autophagy genes (atg7, atg8a) but absent in flies with mutations in FOXO, ATM, ATR, and p53 homologues. The hormetic effect was revealed in Sirt2 mutant males but not in females. On the contrary, the females but not males of JNK/+ mutant strain showed adaptive response. The obtained results demonstrate the essential role of FOXO, SIRT1, JNK, ATM, ATR, and p53 genes in hormesis and radiation adaptive response of the whole organism.

Blood scent. Blood cell production is tightly regulated by cell-intrinsic mechanisms and environmental factors. The study by Utpal Banerjee and colleagues and colleagues reveals that, in [START]Drosophila[END], olfactory signals control hematopoietic progenitor maintenance, thus uncovering a physiological link between sensory perception and hematopoietic response to environmental stress.

Life-history traits of [START]Drosophila melanogaster[END] populations exhibiting early and late eclosion chronotypes. BACKGROUND: The hypothesis that circadian clocks confer adaptive advantage to organisms has been proposed based on its ubiquity across almost all levels of complexity and organization of life-forms. This thought has received considerable attention, and studies employing diverse strategies have attempted to investigate it. However, only a handful of them have examined how selection for circadian clock controlled rhythmic behaviors influences life-history traits which are known to influence Darwinian fitness. The 'early' and 'late' chronotypes are amongst the most widely studied circadian phenotypes; however, life-history traits associated with these chronotypes, and their consequences on Darwinian fitness remain largely unexplored, primarily due to the lack of a suitable model system. Here we studied several life-history traits of [START]Drosophila melanogaster[END] populations that were subjected to laboratory selection for morning (early) and evening (late) emergence. RESULTS: We report that the late eclosion chronotypes evolved longer pre-adult duration as compared to the early eclosion chronotypes both under light/dark (LD) and constant dark (DD) conditions, and these differences appear to be mediated by both clock dependent and independent mechanisms. Furthermore, longer pre-adult duration in the late chronotypes does not lead to higher body-mass at pupariation or eclosion, but the late females were significantly more fecund and lived significantly shorter as compared to the early females. CONCLUSIONS: Coevolution of multiple life-history traits in response to selection on timing of eclosion highlights correlations of the genetic architecture governing timing of eclosion with that of fitness components which suggests that timing ecologically relevant behaviors at specific time of the day might confer adaptive advantage.

Water acquisition and partitioning in [START]Drosophila melanogaster[END]: effects of selection for desiccation-resistance. We examined physiological features related to water balance in five replicate populations of [START]Drosophila melanogaster[END] that have undergone selection for enhanced resistance to desiccation (D populations) and in five replicate control (C) populations. Adult D flies contain 34 % more water than the control flies. We examined two hypotheses for increased water acquisition in the D flies: (i) that they accumulate more water early in development and (ii) that they have a reduced post-eclosion diuretic water loss. We found no evidence of differential water or dry mass acquisition between the C and D populations prior to adulthood. We also found no evidence of differential post-eclosion diuresis, i.e. both C and D groups showed insignificant changes in water volume in the 4 h period immediately after eclosion. In addition, we quantified water content in the intra- and extracellular compartments of the C and D populations and were able to identify the hemolymph as the primary storage site of the 'extra' water carried by the desiccation-resistant flies. We estimated that 68 % of the increased water volume observed in the D flies was contained in the hemolymph. Desiccation-resistance was strongly correlated with hemolymph volume and only weakly with intracellular water volume. Survival during desiccation was also strongly related to the carbohydrate content of the D flies. It has been presumed that the D flies accumulate carbohydrate primarily as intracellular glycogen, which would result in a significant increase in intracellular water volume. We found that carbohydrate content was weakly correlated with intracellular water volume and more strongly with hemolymph volume. The carbohydrate pool in the D flies may, therefore, be contained in the extracellular compartment as well as in cells. These results are suggestive of the importance of modifications in hemolymph volume and hemolymph solute concentrations in the evolution of enhanced desiccation-tolerance in populations of [START]Drosophila melanogaster[END].

Persistence of a Wolbachia infection frequency cline in [START]Drosophila melanogaster[END] and the possible role of reproductive dormancy. Field populations of arthropods are often polymorphic for Wolbachia but the factors maintaining intermediate Wolbachia frequencies are generally not understood. In [START]Drosophila melanogaster[END], Wolbachia frequencies are highly variable across the globe. We document the persistence of a Wolbachia infection frequency cline in [START]D. melanogaster[END] populations from eastern Australia across at least 20 years, with frequencies generally high in the tropics but lower in cool temperate regions. The results are interpreted using a model of frequency dynamics incorporating cytoplasmic incompatibility (CI), imperfect maternal transmission and Wolbachia effects on fitness. Clinal variation is less pronounced in eastern North America which may reflect annual recolonization at higher latitudes. Limited samples from Africa from latitudes matching our tropical and subtropical samples from Australia and North America show comparably high infection frequencies, but some equatorial samples show lower frequencies. Adult dormancy across cold periods may contribute to the Australian Wolbachia cline. Infected flies exposed to cold conditions for an extended period had reduced fecundity and viability, an effect not evident in unexposed controls. These fitness costs may contribute to the relatively low Wolbachia frequencies in Australian temperate areas; whereas different processes, including CI induced by young males, may contribute to higher frequencies in tropical locations.

Latitudinal clines in [START]Drosophila melanogaster[END]: body size, allozyme frequencies, inversion frequencies, and the insulin-signalling pathway. Many latitudinal clines exist in [START]Drosophila melanogaster[END]: in adult body size, in allele frequency at allozyme loci, and in frequencies of common cosmopolitan inversions. The question is raised whether these latitudinal clines are causally related. This review aims to connect data from two very different fields of study, evolutionary biology and cell biology, in explaining such natural genetic variation in [START]D. melanogaster[END] body size and development time. It is argued that adult body size clines, inversion frequency clines, and clines in allele frequency at loci involved in glycolysis and glycogen storage are part of the same adaptive strategy. Selection pressure is expected to differ at opposite ends of the clines. At high latitudes, selection on [START]D. melanogaster[END] would favour high larval growth rate at low temperatures, and resource storage in adults to survive winter. At low latitudes selection would favour lower larval critical size to survive crowding, and increased male activity leading to high male reproductive success. Studies of the insulin-signalling pathway in [START]D. melanogaster[END] point to the involvement of this pathway in metabolism and adult body size. The genes involved in the insulin-signalling pathway are associated with common cosmopolitan inversions that show latitudinal clines. Each chromosome region connected with a large common cosmopolitan inversion possesses a gene of the insulin transmembrane complex, a gene of the intermediate pathway and a gene of the TOR branch. The hypothesis is presented that temperate [START]D. melanogaster[END] populations have a higher frequency of a 'thrifty' genotype corresponding to high insulin level or high signal level, while tropical populations possess a more 'spendthrift' genotype corresponding to low insulin or low signal level.

No trade-off between learning ability and parasitoid resistance in [START]Drosophila melanogaster[END]. Learning ability and immunity to parasites are linked at the physiological level in several insect species. The aim of this work was to investigate the relationship between learning and immunity at an evolutionary level. We tested whether selection for improved learning ability in [START]Drosophila melanogaster[END] led to changes in parasitoid resistance as a correlated response. Similarly, we assayed whether selection for better parasitoid resistance led to a change in learning ability. There was no significant difference between selected and control lines in either case; the estimated confidence intervals for the differences indicate that a trade-off relationship is unlikely.

Consequences of chronic bacterial infection in [START]Drosophila melanogaster[END]. Even when successfully surviving an infection, a host often fails to eliminate a pathogen completely and may sustain substantial pathogen burden for the remainder of its life. Using systemic bacterial infection in [START]Drosophila melanogaster[END], we characterize chronic infection by three bacterial species from different genera - Providencia rettgeri, Serratia marcescens, and Enterococcus faecalis-following inoculation with a range of doses. To assess the consequences of these chronic infections, we determined the expression of antimicrobial peptide genes, survival of secondary infection, and starvation resistance after one week of infection. While higher infectious doses unsurprisingly lead to higher risk of death, they also result in higher chronic bacterial loads among the survivors for all three infections. All three chronic infections caused significantly elevated expression of antimicrobial peptide genes at one week post-infection and provided generalized protection again secondary bacterial infection. Only P. rettgeri infection significantly influenced resistance to starvation, with persistently infected flies dying more quickly under starvation conditions relative to controls. These results suggest that there is potentially a generalized mechanism of protection against secondary infection, but that other impacts on host physiology may depend on the specific pathogen. We propose that chronic infections in [START]D. melanogaster[END] could be a valuable tool for studying tolerance of infection, including impacts on host physiology and behavior.

Characterization of the mus308 gene in [START]Drosophila melanogaster[END]. Among the available mutagen-sensitive mutations in [START]Drosophila[END], those at the mus308 locus are unique in conferring hypersensitivity to DNA cross-linking agents but not to monofunctional agents. Those mutations are also associated with an elevated frequency of chromosomal aberrations, altered DNA metabolism and the modification of a deoxyribonuclease. This spectrum of phenotypes is shared with selected mammalian mutations including Fanconi anemia in humans. In anticipation of the molecular characterization of the mus308 gene, it has been localized cytogenetically to 87C9-87D1,2 on the right arm of chromosome three. Nine new mutant alleles of the gene have been generated by X-ray mutagenesis and one was recovered following hybrid dysgenesis. Characterization of these new alleles has uncovered additional phenotypes of mutations at this locus. Homozygous mus308 flies that have survived moderate mutagen treatment exhibit an altered wing position that is correlated with reduced flight ability and an altered mitochondrial morphology. In addition, observations of elevated embryo mortality are potentially explained by an aberrant distribution of nuclear material in early embryos which is similar to that seen in the mutant giant nuclei.

[START]Drosophila[END] neuroscience: Unravelling the circuits of sensory-motor control in the fly. Effective motor control requires the real-time transmission of information between sensory organs and the motor system. With the powerful techniques that are now available, [START]Drosophila[END] neuroscientists are unravelling the topology of the neural circuits that carry this information in the fly at synaptic resolution.

Genetic variation in [START]Drosophila melanogaster[END] pathogen susceptibility. Genetic variation in susceptibility to pathogens is a central concern both to evolutionary and medical biologists, and for the implementation of biological control programmes. We have investigated the extent of such variation in [START]Drosophila melanogaster[END], a major model organism for immunological research. We found that within populations, different [START]Drosophila[END] genotypes show wide-ranging variation in their ability to survive infection with the entomopathogenic fungus Beauveria bassiana. Furthermore, striking divergence in susceptibility has occurred between genotypes from temperate and tropical African locations. We hypothesize that this may have been driven by adaptation to local differences in pathogen exposure or host ecology. Genetic variation within populations may be maintained by temporal or spatial variation in the costs and benefits of pathogen defence. Insect pathogens are employed widely as biological control agents and entomopathogenic fungi are currently being developed for reducing malaria transmission by mosquitoes. Our data highlight the need for concern about resistance evolution to these novel biopesticides in vector populations.

The effects of genetic background on exercise performance in [START]Drosophila[END]. The use of the [START]Drosophila[END] model for studying the broad beneficial effects of exercise training has grown over the past decade. As work using [START]Drosophila[END] as an exercise model becomes more widespread, the influence of genetic background on performance should be examined in order to better understand its influence on assessments used to quantitatively measure and compare exercise phenotypes. In this article, we review the various methods of exercise training [START]Drosophila[END], and the performance of different wild-type [START]Drosophila[END] strains on various physiological assessments of exercise response. We conclude by summarizing the performance trends of commonly used strains.

Stage-specific effects of candidate heterochronic genes on variation in developmental time along an altitudinal cline of [START]Drosophila melanogaster[END]. BACKGROUND: Previously, we have shown there is clinal variation for egg-to-adult developmental time along geographic gradients in [START]Drosophila melanogaster[END]. Further, we also have identified mutations in genes involved in metabolic and neurogenic pathways that affect development time (heterochronic genes). However, we do not know whether these loci affect variation in developmental time in natural populations. METHODOLOGY/PRINCIPAL FINDINGS: Here, we constructed second chromosome substitution lines from natural populations of [START]Drosophila melanogaster[END] from an altitudinal cline, and measured egg-adult development time for each line. We found not only a large amount of genetic variation for developmental time, but also positive associations of the development time with thermal amplitude and altitude. We performed genetic complementation tests using substitution lines with the longest and shortest developmental times and heterochronic mutations. We identified segregating variation for neurogenic and metabolic genes that largely affected the duration of the larval stages but had no impact on the timing of metamorphosis. CONCLUSIONS/SIGNIFICANCE: Altitudinal clinal variation in developmental time for natural chromosome substitution lines provides a unique opportunity to dissect the response of heterochronic genes to environmental gradients. Ontogenetic stage-specific variation in invected, mastermind, cricklet and CG14591 may affect natural variation in development time and thermal evolution.

Monitoring the effect of pathogenic nematodes on locomotion of [START]Drosophila[END] larvae. One of the key factors that determine the interaction between hosts and their parasites is the frequency of their interactions, which depends on the locomotory behavior of both parts. To address host behavior we used natural infections involving insect pathogenic nematodes and [START]Drosophila melanogaster[END] larvae as hosts. Using a modified version of a recently described method (FIMTrack) to assess several parameters in larger sets of animals, we initially detected specific differences in larval food searching when comparing [START]Drosophila[END] strains. These differences were further influenced by the presence of nematodes. Given a choice, [START]Drosophila[END] larvae clearly avoided nematodes irrespective of their genetic background. Our newly developed methods will be useful to test candidate genes and pathways involved in host/pathogen interactions in general and to assess specific parameters of their interaction.