bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterogeneity of plant mitochondrial responses underpinning respiratory acclimation to the cold in Arabidopsis thaliana leaves
Authors: ARMSTRONG ANNA F. , LOGAN DAVID C. , TOBIN ALYSON K. , O'TOOLE PETER , ATKIN OWEN K. 
Published: March 2006

ABSTRACTIn this study, we investigated whether changes in mitochondrial abundance, ultrastructure and activity are involved in the respiratory cold acclimation response in leaves of the cold‐hardy plant Arabidopsis thaliana. Confocal microscopy [using plants with green fluorescence protein (GFP) targeted to the mitochondria] and transmission electron microscopy (TEM) were used to visualize changes in mitochondrial morphology, abundance and ultrastructure. Measurements of respiratory flux in isolated mitochondria and intact leaf tissue were also made. Warm‐grown (WG, 25/20 °C day/night), 3‐week cold‐treated (CT) and cold‐developed (CD) leaves were sampled. Although CT leaves exhibited some evidence of acclimation (as evidenced by higher rates of respiration at moderate measurement temperatures), it was only the CD leaves that were able to re‐establish respiratory flux within the cold. Associated with the recovery of respiratory flux in the CD leaves were: (1) an increase in the total volume of mitochondria per unit volume of tissue in epidermal cells; (2) an increase in the ratio of cristae to matrix within mesophyll cell mitochondria; and (3) an increase in the capacity of the energy‐producing cytochrome pathway in mitochondria isolated from whole leaf homogenates. Regardless of growth temperature, we found that contrasting cell types exhibited distinct differences in mitochondrial ultrastructure, morphology and abundance. Collectively, our data demonstrated the diversity and tissue‐specific nature of mitochondrial responses that underpin respiratory acclimation to the cold, and revealed the heterogeneity of mitochondrial structure and abundance that exists within leaves.
In vivo localization of manganese in the hyperaccumulator Gossia bidwillii (Benth.) N. Snow & Guymer (Myrtaceae) by cryo‐SEM/EDAX
Authors: FERNANDO DENISE R. , BATIANOFF GEORGE N. , BAKER ALAN J. , WOODROW IAN E. 
Published: March 2006

ABSTRACT Gossia bidwillii (Myrtaceae) is a manganese (Mn)‐hyperaccumulating tree native to subtropical eastern Australia. It typically contains foliar Mn levels in excess of 1% dry weight. However, in G. bidwillii and other Mn‐hyperaccumulating species, the cellular and subcellular localization of Mn has not been measured. Quantitative in vivo cryo‐scanning electron microscopy (SEM)/energy dispersive X‐ray analysis (EDAX) was used to localize Mn and other elements in tissue collected from mature trees growing in a natural population. Cryo‐SEM showed that the leaf mesophyll is differentiated as a double‐layer palisade mesophyll above spongy mesophyll. Transmission electron microscopy (TEM) revealed that the palisade and epidermal cells are highly vacuolated. EDAX data were used to estimate in situ vacuolar Mn concentrations of all cell types in fresh cryo‐fixed leaf tissues. The highest average vacuolar Mn concentration of over 500 mm was found in the upper‐layer palisade mesophyll, while the lowest concentration of around 100 mm was found in the spongy mesophyll. Qualitative in vivo cryo‐SEM/EDAX was employed to further investigate the spatial distribution of Mn in fresh leaf tissues and young bark tissue, which was also found to have a high Mn concentration. It is concluded that Mn distribution in G. bidwillii is quantitatively different to metal distribution in other hyperaccumulating species where the highest localized concentrations of these elements occur in non‐photosynthetic tissues such as epidermal cells and associated dermal structures including trichomes and leaf hairs.
Strong environmental determination of a carotenoid-based plumage trait is not mediated by carotenoid availability
Authors: Hadfield J. D. , Owens I. P. F. 
Published: March 2006

Abstract
Carotenoid-based colours are recognized as having an important signalling function, yet the nature of the mechanisms that maintain their honesty is not well understood. By combining a carotenoid-feeding experiment with a quantitative genetic experiment in a wild population of blue tits (Parus caeruleus), we were able to test predictions that differentiate between proposed mechanisms. If variation in carotenoid ingestion underlies variation in carotenoid-based colour expression, then carotenoid-supplemented birds should have reduced variance in colour. In this study, carotenoid supplementation produced a small but significant change in plumage colouration, but no significant change in variation. These results suggest that variation in carotenoid acquisition is not an important source of variation for this colour trait, and that variation in post-ingestion processes are likely to be more important. The low heritability of this colour trait suggests environmental factors are likely to underlie the majority of variation in these processes.
A time-sequence functional analysis of mating behaviour and genital coupling in Drosophila: role of cryptic female choice and male sex-drive in the evolution of male genitalia
Authors: Jagadeeshan S. , Singh R. S. 
Published: March 2006

Abstract
Male genitalia in Drosophila exemplify strikingly rapid and divergent evolution, whereas female genitalia are relatively invariable. Whereas precopulatory and post-copulatory sexual selection has been invoked to explain this trend, the functional significance of genital structures during copulation remains obscure. We used time-sequence analysis to study the functional significance of external genitalic structures during the course of copulation, between D. melanogaster and D. simulans. This functional analysis has provided new information that reveals the importance of male-driven copulatory mechanics and strategies in the rapid diversification of genitalia. The posterior process, which is a recently evolved sexual character and present only in males of the melanogaster clade, plays a crucial role in mounting as well as in genital coupling. Whereas there is ample evidence for precopulatory and/or post-copulatory female choice, we show here that during copulation there is little or no physical female choice, consequently, males determine copulation duration. We also found subtle differences in copulatory mechanics between very closely related species. We propose that variation in male usage of novel genitalic structures and shifts in copulatory behaviour have played an important role in the diversification of genitalia in species of the Drosophila subgroup.
Delayed effects of larval predation risk and food quality on anuran juvenile performance
Authors: Nicieza A. G. , Álvarez D. , Atienza E. M. S. 
Published: March 2006

Abstract
Metamorphosis can disrupt the correlation structure between juvenile and adult traits, thus allowing relatively independent evolution in contrasting environments. We used a multiple experimental approach to investigate how diet quality and larval predation risk affected the rates of growth and development in painted frogs (Discoglossus galganoi), and how these changes influence post-metamorphic performance. A high-energy diet entailed growth advantages only if predation risk did not constrain energy acquisition, whereas diet quality affected primarily the extension of the larval period. Predation risk influenced juvenile shape, most likely via the effects on growth and differentiation rates. Juvenile frogs emerging from predator environments had shorter legs and longer bodies than those from the nonpredator tanks. However, these morphological changes did not translate into differences in relative jumping performance. Neither size-adjusted lipid storage nor fluctuating asymmetry was significantly influenced by food quality or predation risk. Our data suggest that the post-metamorphic costs of predator avoidance during the larval phase are mostly a consequence of small size at metamorphosis.
Reducing the cost of resistance; experimental evolution in the filamentous fungus Aspergillus nidulans
Authors: Schoustra S. E. , Debets A. J. M. , Slakhorst M. , Hoekstra R. F. 
Published: March 2006

Abstract
We have studied compensatory evolution in a fludioxonil resistant mutant of the filamentous fungus Aspergillus nidulans. In an evolution experiment lasting for 27 weeks (about 3000 cell cycles) 35 parallel strains of this mutant evolved in three different environmental conditions. Our results show a severe cost of resistance (56%) in the absence of fludioxonil and in all conditions the mutant strain was able to restore fitness without loss of the resistance. In several cases, the evolved strain reached a higher fitness than the original sensitive ancestor. Fitness compensation occurred in one, two or three discrete steps. Genetic analysis of crosses between different evolved strains and between evolved and ancestral strains revealed interaction between compensatory mutations and provided information on the number of loci involved in fitness compensation. In addition, we discuss the opportunities for the experimental study of evolutionary processes provided by the filamentous fungus A. nidulans.
Evolution of sex-biased maternal effects in birds: III. Adjustment of ovulation order can enable sex-specific allocation of hormones, carotenoids, and vitamins
Authors: Badyaev A. V. , Acevedo Seaman D. , Navara K. J. , Hill G. E. , Mendonça M. T. 
Published: March 2006

Abstract
Overlap in growth of offspring should constrain the opportunity for sex-biased maternal effects, yet sex-specific allocation of maternal resources among simultaneously growing ova is often observed in vertebrates. In birds, such allocation can be accomplished either by temporal clustering of ova that become the same sex, resulting in sex-biased egg-laying order, or by follicle-specific delivery of maternal resources. Two house finch populations at the northern and southern boundaries of the species range have opposite ovulation sequences of male and female eggs, and thus, in the absence of sex differences in ova growth or sex-specific maternal strategies, would be expected to have opposite sex-specific accumulation of maternal products. We found that the populations had strong and similar gradients of steroid distribution in relation to ovulation order, whereas distribution of carotenoids and vitamins correlated with each follicle's accumulation of steroids. In both populations, temporal bias in production of sons and daughters within a clutch enabled strongly sex-specific acquisition of maternal products, and oocytes of the same sex were highly interdependent in their accumulation of steroids. Moreover, in nests where the sex-bias in relation to ovulation order deviated from population-specific patterns, eggs had highly distinct concentrations of steroids, carotenoids and vitamins. These results and previous findings of sex-specific yolk partitioning among oocytes suggest that oocytes that become males and females are temporally or spatially clustered during their ovarian growth. We discuss the implication of these findings for the evolution of sex-specific maternal resource allocation.
No evidence that experimental manipulation of sexual conflict drives premating reproductive isolation inDrosophila melanogaster
Authors: Wigby S. , Chapman T. 
Published: March 2006

AbstractTheoretical models predict that sexual conflict can drive reproductive isolation by decreasing the probability of matings between individuals from allopatric populations. A recent study in dung flies supported this prediction. To test the generality of this finding we used replicate lines of Drosophila melanogaster that had been selected under high, medium and low levels of sexual conflict, in which the females had evolved differences in their level of resistance to male-induced harm. We compared the proportion of virgin pairs that mated by set time points, for flies from the same replicate within each sexual conflict level vs. flies from different replicates within each sexual conflict level. The results did not support the prediction that, in D. melanogaster, sexual conflict drives population divergence via changes in female willingness to mate. The results were unlikely to be explained by differential inbreeding or by a lack of response to sexual conflict.
Low abundance of Escherichia coli microsatellites is associated with an extremely low mutation rate
Authors: Schlötterer C. , Imhof M. , Wang H. , Nolte V. , Harr B. 
Published: March 2006

Abstract
It is widely assumed that microsatellites are generated by replication slippage, a mutation process specific to repetitive DNA. Consistent with their high mutation rate, microsatellites are highly abundant in most eukaryotic genomes. In Escherichia coli, however, microsatellites are rare and short despite the fact that a high microsatellite mutation rate was described. We show that this high microsatellite instability depends on the presence of the F-plasmid. E. coli cells lacking the F-plasmid have extremely low microsatellite mutation rates. This result provides a possible explanation for the genome-wide low density of microsatellites in E. coli. Furthermore, we show that the F-plasmid induced microsatellite instability is independent of the mismatch repair pathway.
Genetic and environmental variation in immune response of collared flycatcher nestlings
Authors: Cichoń M. , Sendecka J. , Gustafsson L. 
Published: March 2006

Abstract
This paper aims at partitioning genetic and environmental contribution to the phenotypic variance in nestling immune function measured with the hypersensitivity test after inoculation with phytohaemagglutinin. A cross-fostering experiment with artificial enlargement of some broods was conducted. Variation in nestling immune response was related to their common origin, which suggests heritable component of cell-mediated immunity. A common rearing environment also explained a significant part of variation. However, deterioration of rearing conditions as simulated by enlargement of brood size did not affect nestling immunocompetence, although it affected nestling body mass. Variation in body mass explained some of the variation in immune response related to rearing environment, which means that growth is more sensitive to the shifts in rearing conditions than the development of immune function. Heritable variation in immune response suggests that there should be potential for selection to operate and the micro evolutionary changes in immunity of flycatcher nestlings are possible.
Context Dependent Territory Defense: The Importance of Habitat Structure in Anolis sagrei
Authors: Calsbeek Ryan , Marnocha Erin 
Published: March 2006

AbstractTerritoriality is a potentially costly endeavor, and several mechanisms for mitigating the costs of territoriality have been investigated in the wild. For example, territory owners can reduce the costs of defending territory boundaries by prioritizing defense of the most valuable areas within territories, investing less energy in low quality areas. We staged pairwise encounters between adult male lizards on natural territories in the wild, to test whether male brown anoles, Anolis sagrei, would differentially defend certain regions of their territories over others. Based on our observations that male A. sagrei spend most of their time on elevated perches on tree trunks or branches compared with sites on the ground, we predicted that territory residents would respond more aggressively to territory invasions that took place on elevated perches than to invasions on the ground. We measured significant differences in the behavior of residents following invasion on the ground vs. on the elevated perches, and results partially supported our hypothesis. Males performed more displays and approached intruders more often when territory invasion took place on the ground, but were quicker to attack intruders that entered territories on elevated perches. Our hypothesis was only partially supported, potentially indicating that elevated perches are preferred as outposts to monitor valuable sites on the ground. Our study provides evidence that territory defense varies not just among individuals, but also within individuals at different locations in a territory.
Male Song Quality, Egg Size and Offspring Sex in Captive Canaries (Serinus canaria)
Authors: Leitner Stefan , Marshall Rupert C. , Leisler Bernd , Catchpole Clive K. 
Published: March 2006

AbstractLife history theory predicts that females should vary their investment in offspring according to the quality of their mate. In birds, several studies have now shown that females do vary investment according to perceived male quality, by producing larger eggs, investing more in parental care or by manipulating the sex of their offspring. In a captive breeding colony of canaries, we first show that under normal conditions larger eggs in a clutch are more likely to hatch male offspring. In canaries, male song functions in female attraction and females respond more to complex structures in male song called sexy syllables. In a series of experiments, we go on to show first, that females exposed to playback of male song produce larger eggs than those who heard no song. Next, using synthetic songs, we show that females exposed to playback of more attractive songs containing sexy syllables, produced larger eggs than those exposed to simpler songs containing no sexy syllables. However, in a final analysis, we found no evidence from our experiments that females exposed to playback of more attractive songs also produced more male offspring.
Flower Symmetry Preferences in Honeybees and their Crab Spider Predators
Authors: Wignall Anne E. , Heiling Astrid M. , Cheng Ken , Herberstein Marie E. 
Published: March 2006

AbstractFlowers exhibit symmetrical patterns, and innate preferences for symmetry in pollinators like honeybees are documented. Most previous studies of symmetry preferences in honeybees,Apis mellifera, tested levels of asymmetry using artificial flowers or stimuli. Here we investigated the effect of flower asymmetry on flower preferences of honeybees in a novel approach using real flowers, incorporating their spectral properties and how the receivers process the visual signals. Importantly, we also tested the response of an ‘eavesdropping’ predator, the crab spiderThomisus spectabilis, that also utilizes the same flower to prey on honeybees. Flowers (Chrysanthemum frutescens) were manipulated to contain asymmetrical and symmetrical patterns, excluding olfactory cues. Both crab spiders and honeybees exhibited a significant preference for symmetrical flowers. Moreover, honeybees exhibited a significant preference for radial symmetry over bilateral symmetry, but no corresponding effect was recorded in crab spiders. Further analyses demonstrated that flower reflectance and orientation of the axis of symmetry did not affect crab spider decisions. Field observations onT. spectabilisrevealed that the natural variation inC. frutescenssymmetry had no effect on the choice of crab spiders. This indicates that spiders and honeybees may use other flower characteristics, for example, olfactory cues, together with flower symmetry, to make their foraging decisions.
Resistance of Pinus contorta to the European race of Gremmeniella abietina
Authors: Laflamme G. , Rioux D. , Simard M. , Bussières G. , Mallett K. 
Published: March 2006

Summary Pinus contorta seedlings, together with Pinus resinosa and Pinus banksiana seedlings, were planted adjacent to 25‐year‐old red pine trees infected by the European (EU) race of Gremmeniella abietina. Resistance to this race was assessed over 5 years. All P. resinosa seedlings were dead after that period while 65% of P. contorta and 86% of P. banksiana seedlings appeared resistant to the disease. The tip blight that occurred on P. contorta was slightly longer than that observed on P. banksiana. In microscopy, one, two, or even more suberized boundaries were seen to be initiated near the surface of the shoot at the base of healthy needles where they extended downward in the direction of the vascular cambium. Suberized boundaries occasionally crossed the xylem and joined together in the pith region to form continuous barriers around necrotic tissues. However, in most cases, these suberized barriers were not continuous across the shoot and compartmentalization was then completed by other barriers mainly constituted of parenchyma cells and xylem tracheids that accumulated phenolic compounds. Meristematic‐like cells were observed adjacent to the necrophylactic periderm. Tissue regeneration, restoration of cambial activities and formation of traumatic resin canals also seemed to be associated with the defence system of P. contorta against the EU race of G. abietina.
Occurrence of Bursaphelenchus species in declining Pinus sylvestris in a dry Alpine valley in Switzerland
Authors: Polomski J. , Schönfeld U. , Braasch H. , Dobbertin M. , Burgermeister W. , Rigling D. 
Published: March 2006

SummaryWe determined the incidence of Bursaphelenchus species in declining Pinus sylvestris stands in the Swiss Alps. A total of 217 trees showing different degree of decline were sampled from various locations in Valais between 2001 and 2004. Bursaphelenchus species were only found in recently dead or dying trees with an overall incidence of 40%. There was a positive relationship between Bursaphelenchus infestation and blue stain in these trees. Five Bursaphelenchus species were identified: Bursaphelenchus vallesianus, Bursaphelenchus mucronatus, Bursaphelenchus sexdentati, Bursaphelenchus leoni and Bursaphelenchus silvestris. The most frequent species were B. vallesianus detected in 75% and B. mucronatus in 20% of all Bursaphelenchus‐positive trees. Bursaphelenchus vallesianus is a recently described species within the B. sexdentati group, and could be a contributing factor in the observed pine decline in Valais.
Occurrence of Cryphonectria hypovirus 1 in the chestnut blight fungus in Macedonia
Authors: Sotirovski K. , Milgroom M. G. , Rigling D. , Heiniger U. 
Published: March 2006

SummaryIn Macedonia, hypoviruses in the chestnut blight fungus, Cryphonectria parasitica, were first identified in 1995, more than 20 years after the discovery of chestnut blight. Between 1995 and 2000, 488 isolates of the fungus were collected from 19 sites throughout Macedonia. These isolates were screened for hypoviruses by extraction of double‐stranded RNA (dsRNA) and electrophoresis on agarose gels. We found dsRNA of approximately 12 kb in length in 95 isolates in eight subpopulations of the fungus. Subpopulations with the highest virus incidence were Skudrinje (63%) and Jepiste (43%) in the Debar region, and Frangovo (46%) in the Struga region. Virus incidence in other subpopulations was much lower. To test whether the 12‐kb dsRNAs are Cryphonectria hypovirus 1 (CHV‐1), we subjected a sample of 27 isolates to reverse transcription (RT)‐PCR and RFLP analyses. All 27 were identified as CHV‐1 and belonged to the Italian subtype (subtype‐I); all of these isolates were white in culture, typical of CHV‐1‐containing isolates. Most isolates had RFLPs identical to those previously found in other countries of southern Europe. Future studies will investigate hypoviruses from various origins in Macedonia for their biological control potential. Preliminary field surveys identified superficial cankers at all chestnut populations where CHV‐1 was found.