bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative phylogeography of two coastal polychaete tubeworms in the Northeast Atlantic supports shared history and vicariant events
Authors: JOLLY M. T. , VIARD F. , GENTIL F. , THIÉBAUT E. , JOLLIVET D.
Published: March 2006

The historic processes which have led to the present‐day patterns of genetic structure in the marine coastal fauna of the Northeast Atlantic are still poorly understood. While tectonic uplifts and changes in sea level may have caused large‐scale vicariance, warmer conditions during glacial maxima may have allowed pockets of diversity to persist to a much wider extent than in the Northwestern Atlantic. The large‐scale geographic distribution of deeply divergent lineages of the coastal polychaete tubeworms Pectinaria koreni (two clades) and Owenia fusiformis (three clades) were compared using a fragment of the mitochondrial cytochrome oxidase I gene (mtCOI). All lineages were present along the biogeographic transition zone on the north coast of Brittany (France) and we found evidence pointing towards congruence in the timing of cladogenic events between Pectinaria sp. (P. auricoma/P. belgica and P. koreni) and Owenia sp., suggesting a shared history of vicariant events. More conserved 16SrRNA sequences obtained from four species of Pectinariidae together with mtCOI sequences of P. koreni seem consistent with an initial establishment of pectinariids in the north, and a southward colonization of the Northeast Atlantic. Phylogeographic patterns in O. fusiformis were also consistent with a north/south pattern of lineage splitting and congruent levels of divergence were detected between lineages of both species. We observed signatures of both persistence in small northern glacial refugia, and of northwards range expansion from regions situated closer to the Mediterranean. However, whether the recolonization of the Northeast Atlantic by both species actually reflects separate interglacial periods is unclear with regards to the lack of molecular clock calibration in coastal polychaete species.
Set regulation in asexual and sexual Plasmodium parasites reveals a novel mechanism of stage‐specific expression
Authors: Pace Tomasino , Olivieri Anna , Sanchez Massimo , Albanesi Veronica , Picci Leonardo , Kiamos Inga Siden , Janse Chris J. , Waters Andrew P. , Pizzi Elisabetta , Ponzi Marta
Published: March 2006

Transmission of the malaria parasite depends on specialized gamete precursors (gametocytes) that develop in the bloodstream of a vertebrate host. Gametocyte/gamete differentiation requires controlled patterns of gene expression and regulation not only of stage and gender‐specific genes but also of genes associated with DNA replication and mitosis. Once taken up by mosquito, male gametocytes undergo three mitotic cycles within few minutes to produce eight motile gametes. Here we analysed, in two Plasmodium species, the expression of SET, a conserved nuclear protein involved in chromatin dynamics. SET is expressed in both asexual and sexual blood stages but strongly accumulates in male gametocytes. We demonstrated functionally the presence of two distinct promoters upstream of the set open reading frame, the one active in all blood stage parasites while the other active only in gametocytes and in a fraction of schizonts possibly committed to sexual differentiation. In ookinetes both promoters exhibit a basal activity, while in the oocysts the gametocyte‐specific promoter is silent and the reporter gene is only transcribed from the constitutive promoter. This transcriptional control, described for the first time in Plasmodium, provides a mechanism by which single‐copy genes can be differently modulated during parasite development. In male gametocytes an overexpression of SET might contribute to a prompt entry and execution of S/M phases within mosquito vector.
Structural basis for the extended substrate spectrum of CMY‐10, a plasmid‐encoded class C β‐lactamase
Authors: Kim Jae Young , Jung Ha Il , An Young Jun , Lee Jung Hun , Kim So Jung , Jeong Seok Hoon , Lee Kye Joon , Suh Pann‐Ghill , Lee Heung‐Soo , Lee Sang Hee , Cha Sun‐Shin
Published: March 2006

The emergence and dissemination of extended‐spectrum (ES) β‐lactamases induce therapeutic failure and a lack of eradication of clinical isolates even by third‐generation β‐lactam antibiotics like ceftazidime. CMY‐10 is a plasmid‐encoded class C β‐lactamase with a wide spectrum of substrates. Unlike the well‐studied class C ES β‐lactamase from Enterobacter cloacae GC1, the Ω‐loop does not affect the active site conformation and the catalytic activity of CMY‐10. Instead, a three‐amino‐acid deletion in the R2‐loop appears to be responsible for the ES activity of CMY‐10. According to the crystal structure solved at 1.55 Å resolution, the deletion significantly widens the R2 active site, which accommodates the R2 side‐chains of β‐lactam antibiotics. This observation led us to demonstrate the hydrolysing activity of CMY‐10 towards imipenem with a long R2 substituent. The forced mutational analyses of P99 β‐lactamase reveal that the introduction of deletion mutations into the R2‐loop is able to extend the substrate spectrum of class C non‐ES β‐lactamases, which is compatible with the isolation of natural class C ES enzymes harbouring deletion mutations in the R2‐loop. Consequently, the opening of the R2 active site by the deletion of some residues in the R2‐loop can be considered as an operative molecular strategy of class C β‐lactamases to extend their substrate spectrum.
Expression of a putative laccase gene, ZmLAC1, in maize primary roots under stress*
Authors: LIANG MINGXIANG , HAROLDSEN VICTOR , CAI XIAONING , WU YAJUN
Published: March 2006

Laccases are multi‐copper‐containing glycoproteins and comprise a multi‐gene family in plants. However, their physiological functions are still not well understood. We obtained sequence information for a putative laccase gene, ZmLAC1, from maize and studied ZmLAC1 expression in detail. The deduced ZmLAC1 protein was 70% identical to LpLAC5‐4, a laccase from ryegrass. ZmLAC1 was expressed in leaves, stems and roots of maize seedlings. In unstressed maize primary roots, a higher ZmLAC1 transcript level was located in the basal region where cell elongation had ceased compared to the apical 5 mm of the roots where cells were rapidly dividing and elongating. A treatment with 300 mm NaCl resulted in a shortened root elongation zone (< 2 mm) and swelling in the apical 5 mm. Associated with the morphological change, the transcript level of ZmLAC1 was enhanced in the apical 5 mm, reaching a level similar to that in the basal region. Other abiotic stresses tested – such as 28.5% polyethylene glycol (PEG), which caused an inhibition of root elongation comparable to 300 mm NaCl – did not affect ZmLAC1 transcript level. Potential roles of ZmLAC1 in the roots responding to NaCl or other high concentration of salts are discussed.
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

In 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

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.
The blackflies (Diptera: Simuliidae) of Bioko (Republic of Equatorial Guinea) and the Gulf of Guinea with a description of the larvae of the ‘Pomeroy’ form of Simulium cervicornutum
Authors: MUSTAPHA M. , MCCALL P. J. , CHEKE R. A. , POST R. J.
Published: March 2006

Abstract Like many other organisms, Simuliidae often show a high degree of endemism on oceanic islands, and the Gulf of Guinea, including its islands, is a region of general biogeographical interest in view of the uniqueness of its flora and fauna. This paper presents a comprehensive review of the Simuliidae in the region, and is the first faunistic record of blackflies from Bioko. Simuliidae (larvae, pupae and neonate adults) were collected from Bioko and from around Mount Cameroon and compared with previous findings from Mount Cameroon, Príncipe and São Tomé. Twenty‐seven species are known from the region. Twenty‐five species have been recorded around Mount Cameroon, eight species on Bioko, three species on São Tomé and one species on Príncipe. Two taxonomic ‘forms’ (one on Bioko alone, and one on both Bioko and around Mount Cameroon) and one species (found only on São Tomé) are endemic to the region. A study of the variation in the morphology of Simulium cervicornutum revealed two morphotypes, one from Bioko and around Mount Cameroon and the other from the rest of Africa. The speciation and biogeography of the Simuliidae in the Gulf of Guinea are discussed.
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

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

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

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

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

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

Theoretical 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

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

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

Territoriality 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

Life 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

Flowers 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

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

We 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

In 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.
EXERCISE AND SKELETAL MUSCLE GLUCOSE TRANSPORTER 4 EXPRESSION: MOLECULAR MECHANISMS
Authors: McGee Sean L , Hargreaves Mark
Published: March 2006

Skeletal muscle is a highly plastic tissue that has a remarkable ability to adapt to external demands, such as exercise. Many of these adaptations can be explained by changes in skeletal muscle gene expression. A single bout of exercise is sufficient to induce the expression of some metabolic genes. We have focused our attention on the regulation of glucose transporter isoform 4 (GLUT‐4) expression in human skeletal muscle.

Glucose transporter isoform 4 gene expression is increased immediately following a single bout of exercise, and the GLUT‐4 enhancer factor (GEF) and myocyte enhancer factor 2 (MEF2) transcription factors are required for this response. Glucose transporter isoform enhancer factor and MEF2 DNA binding activities are increased following exercise, and the molecular mechanisms regulating MEF2 in exercising human skeletal muscle have also been examined.

These studies find possible roles for histone deacetylase 5 (HDAC5), adenosine monophosphate–activated protein kinase (AMPK), peroxisome proliferator‐activated receptor gamma coactivator 1α (PGC‐1α) and p38 mitogen‐activated protein kinase (MAPK) in regulating MEF2 through a series of complex interactions potentially involving MEF2 repression, coactivation and phosphorylation.

Given that MEF2 is a transcription factor required for many exercise responsive genes, it is possible that these mechanisms are responsible for regulating the expression of a variety of metabolic genes during exercise. These mechanisms could also provide targets for the treatment and management of metabolic disease states, such as obesity and type 2 diabetes, which are characterized by mitochondrial dysfunction and insulin resistance in skeletal muscle.
EVIDENCE FOR A SUPRASPINAL CONTRIBUTION TO HUMAN MUSCLE FATIGUE
Authors: Taylor Janet L , Todd Gabrielle , Gandevia Simon C
Published: March 2006

Muscle fatigue can be defined as any exercise‐induced loss of ability to produce force with a muscle or muscle group. It involves processes at all levels of the motor pathway between the brain and the muscle. Central fatigue represents the failure of the nervous system to drive the muscle maximally. It is defined as a progressive exercise‐induced reduction in voluntary activation or neural drive to the muscle. Supraspinal fatigue is a component of central fatigue. It can be defined as an exercise‐induced decline in force caused by suboptimal output from the motor cortex.

When stimulus intensity is set appropriately, transcranial magnetic stimulation (TMS) over the motor cortex during an isometric maximal voluntary contraction (MVC) of the elbow flexors commonly evokes a small twitch‐like increment in flexion force. This increment indicates that, despite the subject's maximal effort, motor cortical output at the moment of stimulation was not maximal and was not sufficient to drive the motoneurons to produce maximal force from the muscle. An exercise‐induced increase in this increment demonstrates supraspinal fatigue.

Supraspinal fatigue has been demonstrated during fatiguing sustained and intermittent maximal and submaximal contractions of the elbow flexors where it accounts for about one‐quarter of the loss of force of fatigue. It is linked to activity and the development of fatigue in the tested muscles and is little influenced by exercise performed by other muscles.

The mechanisms of supraspinal fatigue are unclear. Although changes in the behaviour of cortical neurons and spinal motoneurons occur during fatigue, they can be dissociated from supraspinal fatigue. One factor that may contribute to supraspinal fatigue is the firing of fatigue‐sensitive muscle afferents that may act to impair voluntary descending drive.
PROTEOMIC ANALYSIS OF RAT AORTA DURING ATHEROSCLEROSIS INDUCED BY HIGH CHOLESTEROL DIET AND INJECTION OF VITAMIN D3
Authors: Almofti Mohamad Radwan , Huang Zhenyu , Yang Pengyuan , Rui Yaocheng , Yang Pengyuan
Published: March 2006

Atherosclerosis (AS) in rats displays important clinical similarities to human AS.

After the experimental model of AS in rat was established and using a proteomic approach, we compared the protein profiling of aorta tissues from healthy and AS rats.

Using two‐dimensional electrophoresis (2‐DE), over 1878 protein species were separated; among them, 1239 protein spots were matched between different gels with average matching rate of approximately 66%. Gel analysis and protein characterization have identified 58 protein spots whose abundance is significantly altered in AS rats.

By using matrix‐associated laser desorption ionization time‐of‐flight mass spectrometer (MALDI‐TOF‐MS) and NCBInr database, 46 proteins were successfully identified. Among them, 18 proteins were of increased abundance in diseased tissues including a group of oxidization‐related enzymes such as peroxiredoxin2 and NADH dehydrogenase Fe‐S protein 6, components of inflammatory pathways such as lamin A, while 28 proteins were of decreased abundance in the diseased state, including CaM‐KII inhibitory protein, transferring, fructose‐bisphosphate aldolase.

We believe that these results would give insights into the cellular and molecular mechanisms involved in AS development and might lead to the discovery of novel diagnostic markers and new therapeutic opportunities.
NARINGIN DOES NOT ALTER CAFFEINE PHARMACOKINETICS, ENERGY EXPENDITURE, OR CARDIOVASCULAR HAEMODYNAMICS IN HUMANS FOLLOWING CAFFEINE CONSUMPTION
Authors: Ballard Tasha LP , Halaweish Fathi T , Stevermer Cheryl L , Agrawal Puja , Vukovich Matthew D
Published: March 2006

Naringin, a grapefruit constituent interacts with many medications including caffeine, a popular weight loss supplement. The purpose of the current study was to identify changes in caffeine pharmacokinetics, resting energy expenditure (REE), oxygen consumption (VO2) and respiratory exchange ratio (RER) after an acute dosage of caffeine and naringin.

Using a double‐blinded, counterbalanced design, REE, VO2, and RER were measured before and systematically for 8 h after a single dosage of caffeine (CAF, 200 mg) with and without naringin (100 mg (CN100) or 200 mg (CN200)) in 10 apparently healthy individuals. A standardized meal was provided following 240‐minute measurements (400 kcals; 35 g carbohydrate; 27 g protein; 7 g fat).

Caffeine, CN100, CN200 did not alter VO2 or VO2 area under the curve (137 301 ± 8318, 139 729 ± 9300, 134 297 ± 8318, mL/480 min). Resting energy expenditure (k/cals) was 10.0 ± 1.4% higher with CAF versus CN200 (6.0 ± 1.4%) and CN100 (6 ± 1.5%) at 240 min (P = 0.07) which was then negated following a standardized meal. Percent change in RER from pre to 240 min and pre to 480 min was not different between the CAF, CN100, or CN200 (–0.2 ± 1.7%, 1.7 ± 1.7%, –2.8 ± 1.9%).

Although caffeine alone suggests a trend of increased REE, the results of the present study indicate that concurrent consumption of caffeine with naringin in acute dosages does not affect RER, VO2, and prevents the increase of REE in adult humans. The results suggest that the interaction of grapefruit juice and caffeine may be due to constituents of grapefruit juice other than naringin or in addition to naringin.
ISOFLURANE AND OTHER COMMONLY USED ANAESTHETICS DO NOT PROTECT THE ISOLATED BUFFER PERFUSED MOUSE HEART FROM ISCHEMIA‐REPERFUSION INJURY
Authors: Galagudza Michael , Vaage Jarle , Valen Guro
Published: March 2006

Some anaesthetic agents such as barbiturates and opioids possess cardioprotective properties in rats, rabbits, dogs and pigs. The purpose of this study was to evaluate the effects of some commonly used anaesthetic agents (pentobarbital, isoflurane and a mixture of midazolam, fentanyl and fluanisone) on the tolerance of the isolated mouse heart to ischaemia‐reperfusion injury.

The isolated, Langendorff‐perfused hearts were subjected to 45 min of global ischaemia followed by 60 min of reperfusion. Left ventricular pressures, heart rate and coronary flow were measured and infarct size was determined using triphenyltetrazolium staining.

There were no differences in haemodynamic variables during reperfusion between groups. Infarct size was not influenced by the choice of anaesthesia.

None of the anaesthesia protocols exerted significant protective effects on the ischaemic‐reperfused isolated mouse heart performance. In mice, isoflurane as well as pentobarbital, opioids and benzodiazepines may be safely used for anaesthesia without a risk of protective side‐effects in isolated mouse heart studies.
CHARACTERIZATION OF RWJ‐351647, A NOVEL NONPEPTIDE VASOPRESSIN V2RECEPTOR ANTAGONIST
Authors: Gunnet Joseph W , Matthews Jay M , Maryanoff Bruce E , De Garavilla Lawrence , Andrade‐Gordon Patricia , Damiano Bruce , Hageman William , Look Richard , Stahle Paul , Streeter Anthony J , Wines Pamela G , Demarest Keith T
Published: March 2006

Antagonists of the V2vasopressin (AVP) receptor are aquaretic agents, inhibiting water resorption without stimulating electrolyte excretion. In this set of experiments, a novel V2receptor antagonist, RWJ‐351647, was characterizedin vitroandin vivo.

RWJ‐351647 displaced3H‐AVP binding from cloned human V2and V1Areceptors withKivalues of 1 nmol/L and 24 nmol/L. In assays using transfected HEK293 cells expressing either human or rat V2receptors, RWJ‐351647 inhibited AVP‐induced cAMP accumulation withKivalues of 3 nmol/L and 6 nmol/L, respectively.

RWJ‐351647 was very selective in binding assays and showed only weak functional antagonist activity at either the cloned human V1Band oxytocin receptors or the human platelet V1Areceptor. No agonist activity was seen with the compound at any receptor.

Pharmacokinetic studies in rats showed RWJ‐351647 to be 41.9% bioavailable after a single oral administration. After repeated daily dosing over 5 days, the oral bioavailability remained at 43.9% with no change in the compound peak plasma levels or clearance rate.

In efficacy studies, RWJ‐351647 increased urine output and decreased urine osmolality with oral doses as low as 0.1 mg/kg and 1.0 mg/kg in rats and cynomolgus monkeys, respectively. In a multiple dose study in primates, RWJ‐351647 maintained a consistent aquaretic effect over 10 days without increasing sodium or potassium excretion.

In summary, RWJ‐351647 was shown to be a selective and potent V2receptor antagonist with sustainable aquaretic activity in both rats and primates. The preclinical data suggest that RWJ‐351647 is a potent and effective aquaretic agent with potential for use in diseases characterized by water retention.
EFFECTS OF INSULIN TREATMENT ON HEART RHYTHM, BODY TEMPERATURE AND PHYSICAL ACTIVITY IN STREPTOZOTOCIN‐INDUCED DIABETIC RAT
Authors: Howarth FC , Jacobson M , Shafiullah M , Adeghate E
Published: March 2006

Streptozotocin (STZ)‐induced diabetic cardiomyopathy is frequently associated with depressed diastolic/systolic function and altered heart rhythm.

The effects of insulin treatment on heart rhythm, body temperature and physical activity in STZ‐induced diabetic rats were investigated using biotelemetry techniques.

Transmitter devices were surgically implanted in the peritoneal cavity of young adult male Wistar rats. Electrodes from the transmitter were arranged in Einthoven bipolar – Lead II configuration. Electrocardiogram, physical activity and body temperature data were recorded with a telemetry system for 10 days before STZ treatment, for 20 days following administration of STZ (60 mg/kg) and thereafter, for 30 days while rats received daily insulin.

Heart rate, physical activity and body temperature declined rapidly 3–5 days after administration of STZ. Pre‐STZ heart rate was 362 ± 7 b.p.m., falling to 266 ± 12 b.p.m. 5–15 days after STZ with significant recovery to 303 ± 14 b.p.m. 10–20 days after commencement of insulin. Pre‐STZ body temperature was 37.5 ± 0.1C, falling to 37.2 ± 0.2C 5–15 days after STZ with significant recovery to 37.5 ± 0.1C 10–20 days after commencement of insulin. Physical activity and heart rate variability were also reduced after STZ but there was no significant recovery during insulin replacement.

5. 

Defective autonomic regulation and/or mechanisms of control that are intrinsic to the heart may underlie disturbances in heart rhythm in the STZ‐induced diabetic rat.
PROTECTIVE EFFECT OF PAEONIFLORIN ON IMMUNOLOGICAL LIVER INJURY INDUCED BY BACILLUS CALMETTE‐GUERIN PLUS LIPOPOLYSACCHARIDE: MODULATION OF TUMOUR NECROSIS FACTOR‐α AND INTERLEUKIN‐6 mRNA
Authors: Liu Dao‐Fang , Wei Wei , Song Li‐Hua
Published: March 2006

1. 

Paeoniflorin is one of the main effective components of the total glucosides of paeony (TGP) extracted from the root of Paeonia lactiflora which has been used for gynaecological problems and for cramp, pain and giddiness for over 1 500 years in Chinese medicine. Anti‐inflammatory, antioxidative, antihepatic injury and immunoregulatory activities of TGP have been extensively proved in our laboratory for many years. Our present study investigates the effects and mechanisms of paeoniflorin on immunological liver injury in mice.

A model of immunological liver injury was induced by tail vein injection of bacillus Calmette‐Guérin (BCG) and lipopolysaccharide (LPS) in mice. Activities of serum alanine aminotransferase (ALT) were measured by biochemical methods. Hepatic tissue sections were stained with haematoxylin and eosin and examined under a light microscope. Tumor necrosis factor (TNF)‐a, interleukin (IL)‐6, lipopolysaccharide binding protein (LBP) and CD14 mRNA (messenger ribonucleic acid) expression in mouse liver were determined by semiquantitative reverse transcription polymerase chain reaction (RT‐PCR) analysis.

Immunological liver injury induced by BCG plus LPS was successfully duplicated. Serum ALT activities were significantly decreased by paeoniflorin. (25, 50, 100 mg/kg). Histological examination demonstrated that paeoniflorin could attenuate the area and extent of necrosis and reduce the immigration of inflammatory cells. The increase in TNF‐a, LBP and CD14 mRNA expression in mouse liver after BCG and LPS injection was significantly decreased by paeoniflorin (100 mg/kg) and was changed by paeoniflorin (25, 50 mg/kg) at different time‐point. The augmentation of IL‐6 mRNA in mouse liver was markedly increased by paeoniflorin at 1 h and 3 h after LPS injection.

Paeoniflorin could significantly protect against immunological liver injury in mice. TNF‐a, IL‐6, LBP and CD14 mRNA expression in mouse liver may be involved in BCG plus LPS induced liver injury. The protective mechanism of paeoniflorin might be partially related to modulation of TNF‐a, IL‐6, LBP and CD14 mRNA expressions in mouse liver.
ACUTE DILATORY AND NEGATIVE INOTROPIC EFFECTS OF HOMOCYSTEINE ARE INHIBITED BY AN ADENOSINE BLOCKER
Authors: Kennedy Richard H , Owings Richard , Joseph Jacob , Melchert Russell B , Hauer‐Jensen Martin , Boerma Marjan
Published: March 2006

Previous studies have shown that homocysteine elicits acute negative inotropic and coronary vasodilatory effects in rat hearts. In addition, this earlier work suggested that the inotropic action is mediated via an endothelium‐derived agent that is neither nitric oxide (NO) nor a cyclooxygenase product, while the coronary actions were found to be antagonized by the NOS inhibitor l‐NNA. Current experiments, which utilized coronary‐perfused rat hearts, were designed to determine if muscarinic or adenosine receptors are involved in these acute actions of homocysteine.

Left ventricular developed pressure was used as a measure of systolic function in electrically paced, Langendorff‐perfused heart with coronary pressure being used to monitor coronary vascular tone. Acute effects of homocysteine (10–300 mmol/L) were examined in the presence and absence of 1 ¥ 10‐6 mol atropine or 7 ¥ 10‐5 mol 8‐(p‐sulfophenyl) theophylline (SPT), a non‐selective adenosine receptor antagonist.

Atropine had no effect on either the inotropic or vascular actions of homocysteine. In contrast, SPT partially antagonized both actions of the amino acid with the antagonism of the vasodilation being much greater than its inhibition of the negative inotropic effect. Experiments with adenosine demonstrated that the selected dose of SPT elicited marked rightward shifts in the dose–response curves for both the inotropic and vascular actions.

Current results suggest that adenosine plays a role in both the negative inotropic and vasodilatory actions of homocysteine. However, the relatively minor antagonistic action of SPT on the inotropic effect of homocysteine suggests that additional endothelium‐derived mediators underlie its effects on contractility.