bluuebunny/crossref_metadata_2025_split huggingface dataset:
Are behavioural traits in prey sensitive to the risk imposed by predatory fish?
Authors: WOHLFAHRT BIANCA , MIKOLAJEWSKI DIRK JOHANNES , JOOP GERRIT , SUHLING FRANK 
Published: November 2005

Summary1. Behavioural differences among prey species may result from evolutionary adaptations that facilitate coexistence with different predators and influence vulnerability to predators. It has been hypothesised that prey species modify their behaviour in relation to the risk posed by particular predators.2. We examined the relationship between anti‐predator behaviour and predation risk in five species of larval odonates in combination with three predatory fish species (perch, gudgeon and rudd) that differ in foraging behaviour. The odonates,Platycnemis pennipes,Coenagrion puella,Lestes sponsa,Sympetrum striolatumandLibellula depressa, differ with regard to their life cycle and habitat, including water depth, occurrence in temporary ponds and co‐existence with fish.3. The odonate species differed in their response to fish: (i) Two species showed a flexible response. LarvalC. puellareduced activity in the presence of fish, regardless of species, whereasL. depressaaltered their activity only in the presence of gudgeon. (ii) Independent of fish species, all odonates exceptL. depressaexhibited spatial avoidance of fish. This was interpreted as a more general anti‐predator response. (iii) In some cases the odonates showed no response to predators and their behaviour was thus independent of predation risk.4. Our results confirm that all odonates responded to the presence of at least some predatory fish, and that some odonate species discriminated between fish species. However, we found no significant correlation between behavioural modifications and predation risk, indicating that anti‐predator responses and predation risk depend on the particular predator and the species being preyed on.
Trade‐offs between the shade‐avoidance response and plant resistance to herbivores? Tests with mutant Cucumis sativus
Authors: McGUIRE R. , AGRAWAL A. A. 
Published: November 2005

Summary

Plants exhibit adaptations to many stresses, including light competition and herbivory. The expression of these traits may interact negatively, potentially instigating a trade‐off.
We employed a combination of genetically altered Cucumis sativus varieties and phenotypic manipulations to test for trade‐offs in field experiments. The different genetic lines of C. sativus were altered in their phytochrome‐mediated shade responses and the production of terpenoid defence compounds.
Cucumber plants constitutively expressing the shade‐avoidance response had 93% more herbivory by specialist beetles compared with wild types. The long‐hypocotyl mutants also produced leaves with fewer trichomes, greater toughness and a higher carbon to nitrogen ratio (C : N) than wild types. Plants lacking defensive cucurbitacins had 23% longer internodes than the cucurbitacin‐producing line.
We then manipulated the plant phenotype by artificially imposing neighbours’ shade on plants with and without cucurbitacins. As expected, plants responded to shade by growing longer hypocotyls and first internodes, but few trade‐offs were found between plant line and shade treatment and, although herbivory levels were very low, there was a trend towards reduced damage on shaded plants.
The use of genetically altered plant lines provided strong evidence for the trade‐off hypothesis, while phenotypic manipulations did not support the hypothesis.
A distinct seasonal pattern of the ratio of soil respiration to total ecosystem respiration in a spruce‐dominated forest
Authors: Davidson E. A. , Richardson A. D. , Savage K. E. , Hollinger D. Y. 
Published: November 2005

AbstractAnnual budgets and fitted temperature response curves for soil respiration and ecosystem respiration provide useful information for partitioning annual carbon budgets of ecosystems, but they may not adequately reveal seasonal variation in the ratios of these two fluxes. Soil respiration (Rs) typically contributes 30–80% of annual total ecosystem respiration (Reco) in forests, but the temporal variation of these ratios across seasons has not been investigated. The objective of this study was to investigate seasonal variation in the Rs/Reco ratio in a mature forest dominated by conifers at Howland, ME, USA. We used chamber measurements of Rs and tower‐based eddy covariance measurements of Reco. The Rs/Reco ratio reached a minimum of about 0.45 in the early spring, gradually increased through the late spring and early summer, leveled off at about 0.65 for the summer, and then increased again to about 0.8 in the autumn. A spring pulse of aboveground respiration presumably causes the springtime minimum in this ratio. Soil respiration ‘catches up’ as the soils warm and as root growth presumably accelerates in the late spring, causing the Rs/Reco ratios to increase. The summertime plateau of Rs/Reco ratios is consistent with summer drought suppressing Rs that would otherwise be increasing, based on increasing soil temperature alone, thus causing the Rs/Reco ratios to not increase as soils continue to warm. Declining air temperatures and litter fall apparently contribute to increased Rs/Reco ratios in the autumn. Differences in phenology of growth of aboveground and belowground plant tissues, mobilization and use of stored substrates within woody plants, seasonal variation in photosynthate and litter substrates, and lags between temperature changes of air and soil contribute to a distinct seasonal pattern of Rs/Reco ratios.
An unusual distribution of the kdr gene among populations of Anopheles gambiae on the island of Bioko, Equatorial Guinea
Authors: Reimer L. J. , Tripet F. , Slotman M. , Spielman A. , Fondjo E. , Lanzaro G. C. 
Published: November 2005

AbstractIn West Africa, Anopheles gambiae exists in discrete subpopulations known as the M and S molecular forms. Although these forms occur in sympatry, pyrethroid knock‐down resistance (kdr) is strongly associated with the S molecular form. On the island of Bioko, Equatorial Guinea we found high frequencies of the kdr mutation in M form individuals (55.8%) and a complete absence of kdr in the S form. We also report the absence of the kdr allele in M and S specimens from the harbour town of Tiko in Cameroon, representing the nearest continental population to Bioko. The kdr allele had previously been reported as absent in populations of An. gambiae on Bioko. Contrary to earlier reports, sequencing of intron‐1 of this sodium channel gene revealed no fixed differences between M form resistant and susceptible individuals. The mutation may have recently arisen independently in the M form on Bioko due to recent and intensive pyrethroid application.
Expressed sequence tags from the midgut and an epithelial cell line of Chironomus tentans: annotation, bioinformatic classification of unknown transcripts and analysis of expression levels
Authors: Arvestad L. , Visa N. , Lundeberg J. , Wieslander L. , Savolainen P. 
Published: November 2005

AbstractExpressed sequence tags (ESTs) were generated from two Chironomus tentans cDNA libraries, constructed from an embryo epithelial cell line and from larva midgut tissue. 8584 5′‐end ESTs were generated and assembled into 3110 tentative unique transcripts, providing the largest contribution of C. tentans sequences to public databases to date. Annotation using Blast gave 1975 (63.5%) transcripts with a significant match in the major gene/protein databases, 1170 with a best match to Anopheles gambiae and 480 to Drosophila melanogaster. 1091 transcripts (35.1%) had no match to any database. Studies of open reading frames suggest that at least 323 of these contain a coding sequence, indicating that a large proportion of the genes in C. tentans belong to previously unknown gene families.
Characterization of a blood activated chitinolytic system in the midgut of the sand fly vectors Lutzomyia longipalpis and Phlebotomus papatasi
Authors: Ramalho‐Ortigão J. M. , Kamhawi S. , Joshi M. B. , Reynoso D. , Lawyer P. G. , Dwyer D. M. , Sacks D. L. , Valenzuela J. G. 
Published: November 2005

AbstractWe characterized a cDNA from Phlebotomus papatasi, PpChit1, which encodes a midgut specific chitinase and show the presence of a functional, blood‐induced chitinolytic system in sand flies. PpChit1 is detected only in the midgut and is regulated by blood feeding. A recombinant protein (rPpChit1) produced in HEK 293‐F cells exhibited a similar activity profile to that found in the native protein against several specific substrates, including an oligomeric glycol chitin and synthetic 4‐methyl‐umbelliferone labelled substrates. Western blotting showed that the native protein is recognized by mouse polyclonal antibodies against rPpChit1. Additionally, the rPpChit1 and the native chitinase displayed similar retention times in a HPLC size fractionation column. When added to rPpChit1 or to midgut lysates, PpChit1 sera reduced chitinolytic activity by 65–70%.
Parasitism shaping host life‐history evolution: adaptive responses in a marine gastropod to infection by trematodes
Authors: FREDENSBORG B. L. , POULIN R. 
Published: November 2005

Summary

Variation in life‐history strategies among conspecific populations indicates the action of local selective pressures; recently, parasitism has been suggested as one of these local forces.
Effects of trematode infections on reproductive effort, juvenile growth, size at maturity and susceptibility were investigated among different natural populations of the marine gastropod Zeacumantus subcarinatus, Sowerby 1855.
Reproductive effort was not higher in uninfected snails from populations experiencing a high trematode prevalence, but females from high prevalence populations produced significantly larger offspring compared with their conspecifics from other populations.
Juvenile growth rate was significantly higher in laboratory‐raised snails originating from females in a high prevalence population compared with other populations.
Size at maturity, determined by the appearance of functional gonads, was significantly and negatively related to trematode prevalence, and positively related to mean snail size, across 10 populations in the study area.
There was no evidence of different host resistance against trematodes in sentinel snails from high and low prevalence populations exposed to the same infection pressure in the field.
Our results strongly indicate that Z. subcarinatus adapt to trematodes by reaching maturity early, thereby maximizing their chance of reproducing in populations experiencing a high prevalence of infection by castrating trematodes.
Corticosterone Actions on the Hippocampal Brain‐Derived Neurotrophic Factor Expression are Mediated by Exon IV Promoter
Authors: Hansson A. C. , Sommer W. H. , Metsis M. , Strömberg I. , Agnati L. F. , Fuxe K. 
Published: November 2005

AbstractBrain‐derived neurotrophic factor (BDNF) expression is strongly regulated by adrenocorticosteroids via activated gluco‐ and mineralocorticoid receptors. Four separate promoters are located upstream of the BDNF noncoding exons I to IV and may thus be involved in adrenocorticosteroid‐mediated gene regulation. In adrenalectomised rats, corticosterone (10 mg/kg s.c.) induces a robust down‐regulation of both BDNF mRNA and protein levels in the hippocampus peaking at 2–8 h. To study the role of the individual promoters in the corticosterone response, we employed exon‐specific riboprobe in situ hybridisation as well as real‐time polymerase chain reaction (PCR) in the dentate gyrus. We found a down‐regulation, mainly of exon IV and the protein‐coding exon V, in nearby all hippocampal subregions, but exon II was only down‐regulated in the dentate gyrus. Exon I and exon III transcripts were not affected by corticosterone treatment. The results could be confirmed with real‐time PCR in the dentate gyrus. It appears as if the exon IV promoter is the major target for corticosterone‐mediated transcriptional regulation of BDNF in the hippocampus.
Two processivity clamp interactions differentially alter the dual activities of UmuC
Authors: Beuning Penny J. , Sawicka Dorota , Barsky Daniel , Walker Graham C. 
Published: November 2005

SummaryDNA polymerases of the Y family promote survival by their ability to synthesize past lesions in the DNA template. One Escherichia coli member of this family, DNA pol V (UmuC), which is primarily responsible for UV‐induced and chemically induced mutagenesis, possesses a canonical β processivity clamp‐binding motif. A detailed analysis of this motif in DNA pol V (UmuC) showed that mutation of only two residues in UmuC is sufficient to result in a loss of UV‐induced mutagenesis. Increased levels of wild‐type β can partially rescue this loss of mutagenesis. Alterations in this motif of UmuC also cause loss of the cold‐sensitive and β‐dependent synthetic lethal phenotypes associated with increased levels of UmuD and UmuC that are thought to represent an exaggeration of a DNA damage checkpoint. By designing compensatory mutations in the cleft between domains II and III in β, we restored UV‐induced mutagenesis by a UmuC β‐binding motif variant. A recent co‐crystal structure of the ‘little finger’ domain of E. coli pol IV (DinB) with β suggests that, in addition to the canonical β‐binding motif, a second site of pol IV (303VWP305) interacts with β at the outer rim of the dimer interface. Mutational analysis of the corresponding motif in UmuC showed that it is dispensable for induced mutagenesis, but that alterations in this motif result in loss of the cold‐sensitive phenotype. These two β interaction sites of UmuC affect the dual functions of UmuC differentially and indicate subtle and sophisticated polymerase management by the β clamp.
Mating type regulation of cellular tolerance to DNA damage is specific to the DNA post‐replication repair and mutagenesis pathway
Authors: Barbour Leslie , Xiao Wei 
Published: November 2005

SummaryIn order to help further define DNA post‐replication repair (PRR), a conditional synthetic lethal screen was employed to identify new genes involved in the PRR pathway. A synthetic lethal screen with the mms2 mutation resulted in the recovery of two suppressor mutations responsible for regulating PRR. The recovered suppressors are the mating type genes and SIR3. Indeed, controlled expression of both mating type genes or deletion of SIR3 rescued the conditional synthetic lethal mutant phenotypes. Furthermore, comprehensive analyses suggest that mating type heterozygosity confers tolerance to a broad range of DNA damage, and that this effect is limited to all PRR pathway mutations, but does not apply to base excision repair, nucleotide excision repair or recombination repair mutants. In addition, the tolerance conferred to PRR mutants as a result of mating type heterozygosity is dependent on a functional homologous recombination but not the non‐homologous end‐joining pathway. Thus, mating type status appears to be responsible for signalling DNA content and possibly cell cycle stage, allowing the cell to select the most efficient means to repair the DNA damage.
Cloning, functional expression and primary characterization of Vibrio parahaemolyticus K+/H+ antiporter genes in Escherichia coli
Authors: Radchenko Martha V. , Waditee Rungaroon , Oshimi Sawako , Fukuhara Masahiro , Takabe Teruhiro , Nakamura Tatsunosuke 
Published: November 2005

SummaryThe regulation of internal Na+ and K+ concentrations is important for bacterial cells, which, in the absence of Na+ extrusion systems, cannot grow in the presence of high external Na+. Likewise, bacteria require K+ uptake systems when the external K+ concentration becomes too low to support growth. At present, we have little knowledge of K+ toxicity and bacterial outward‐directed K+ transport systems. We report here that high external concentrations of K+ at alkaline pH are toxic and that bacteria require K+ efflux and/or extrusion systems to avoid excessive K+ accumulation. We have identified the first example of a bacterial K+(specific)/H+ antiporter, Vp‐NhaP2, from Vibrio parahaemolyticus. This protein, a member of the cation : proton antiporter‐1 (CPA1) family, was able to mediate K+ extrusion from the cell to provide tolerance to high concentrations of external KCl at alkaline pH. We also report the discovery of two V. parahaemolyticus Na+/H+ antiporters, Vp‐NhaA and Vp‐NhaB, which also exhibit a novel ion specificity toward K+, implying that they work as Na+(K+)/H+ exchangers. Furthermore, under specific conditions, Escherichia coli was able to mediate K+ extrusion against a K+ chemical gradient, indicating that E. coli also possesses an unidentified K+ extrusion system(s).
Domains of group A streptococcal M protein that confer resistance to phagocytosis, opsonization and protection: implications for vaccine development
Authors: McArthur Jason D. , Walker Mark J. 
Published: November 2005

Summary Streptococcus pyogenes (group A streptococcus) colonizes skin and throat tissues resulting in a range of benign and serious human diseases. Opsonization and phagocytosis are important defence mechanisms employed by the host to destroy group A streptococci. Antisera against the cell‐surface M protein, of which over 150 different types have been identified, are opsonic and contribute to disease protection. In this issue of Molecular Microbiology, Sandin and colleagues have comprehensively analysed the regions of M5 protein that contribute to phagocytosis resistance and opsonization. Human plasma proteins bound to M5 protein B‐ and C‐repeats were shown to block opsonization, an observation that needs to be carefully considered for the development of M protein‐derived vaccines. While safe and efficacious human group A streptococcal vaccines are not commercially available, candidate M protein‐derived vaccines have shown promise in murine vaccine models and a recent phase 1 human clinical trial.
The Bacillus subtilis spore coat protein interaction network
Authors: Kim Hosan , Hahn Marlene , Grabowski Paul , McPherson Derrell C. , Otte Michele M. , Wang Rong , Ferguson Caitlin C. , Eichenberger Patrick , Driks Adam 
Published: November 2005

SummaryBacterial spores are surrounded by a morphologically complex, mechanically flexible protein coat, which protects the spore from toxic molecules. The interactions among the over 50 proteins that make up the coat remain poorly understood. We have used cell biological and protein biochemical approaches to identify novel coat proteins in Bacillus subtilis and describe the network of their interactions, in order to understand coat assembly and the molecular basis of its protective functions and mechanical properties. Our analysis characterizes the interactions between 32 coat proteins. This detailed view reveals a complex interaction network. A key feature of the network is the importance of a small subset of proteins that direct the assembly of most of the coat. From an analysis of the network topology, we propose a model in which low‐affinity interactions are abundant in the coat and account, to a significant degree, for the coat's mechanical properties as well as structural variation between spores.
Structure–function analysis of the plasma membrane‐ localized Arabidopsis defense component ACD6
Authors: Lu Hua , Liu Yang , Greenberg Jean T. 
Published: November 2005

SummaryThe ACCELERATED CELL DEATH 6 (ACD6) protein, composed of an ankyrin‐repeat domain and a predicted transmembrane region, is a necessary positive regulator of Arabidopsis defenses. ACD6 overexpression confers enhanced disease resistance by priming stronger and quicker defense responses during pathogen infection, plant development or treatment with an agonist of the key defense regulator salicylic acid (SA). Modulation of ACD6 affects both SA‐dependent and SA‐independent defenses. ACD6 localizes to the plasma membrane and is an integral membrane protein with a cytoplasmic ankyrin domain. An activated version of ACD6 with a predicted transmembrane helix mutation called ACD6‐1 has the same localization and overall topology as the wild‐type protein. A genetic screen for mutants that suppress acd6‐1‐conferred phenotypes identified 17 intragenic mutations of ACD6. The majority of these mutations reside in the ankyrin domain and in predicted transmembrane helices, suggesting that both ankyrin and transmembrane domains are important for ACD6 function. One mutation (S638F) also identified a key residue in a putative loop between two transmembrane helices. This mutation did not alter the stability or localization of ACD6, suggesting that S635 is a critical residue for ACD6 function. Based on structural modeling, two ankyrin domain mutations are predicted to be in surface‐accessible residues. As ankyrin repeats are protein interaction modules, these mutations may disrupt protein–protein interactions. A plausible scenario is that information exchange between the ankyrin and transmembrane domains is involved in activating defense signaling.
Histochemical staining and quantification of plant mitochondrial respiratory chain complexes using blue‐native polyacrylamide gel electrophoresis
Authors: Sabar Mohammed , Balk Janneke , Leaver Christopher J. 
Published: November 2005

SummaryOur knowledge of the respiratory chain and associated defects depends on the study of the multisubunit protein complexes in the inner mitochondrial membrane. Functional analysis of the plant mitochondrial respiratory chain has been successfully achieved by a combination of blue‐native polyacrylamide gel electrophoresis (BN‐PAGE) for separation of the protein complexes, and in‐gel histochemical staining of the enzyme activities. We have optimized this powerful technique by determining linear ranges of amount of protein and enzyme activity for each respiratory complex. Time courses of the in‐gel enzyme activities were also performed to determine optimal reaction times. Using the in‐gel activity staining method we have previously shown decreased activity of complex V (F1F0‐ATPase) in male‐sterile sunflowers (Sabar et al., 2003). Here we have identified unique supercomplexes comprising complex IV (cytochrome c oxidase) in sunflower mitochondria. This method therefore represents a reliable tool for the diagnosis of respiratory dysfunction. In addition, the wider application of BN‐PAGE in combination with enzyme activity staining is discussed.
Genetic diversity of herbicide‐resistant and ‐susceptible Avena fatua populations in North Dakota and Minnesota
Authors: MENGISTU L W , MESSERSMITH C G , CHRISTOFFERS M J 
Published: November 2005

SummaryGenetic diversity within and among 20 herbicide‐resistant (HR) and 16 herbicide‐susceptible (HS) Avena fatua multi‐field populations was determined using 82 polymorphic loci resulting from two intersimple sequence repeat (ISSR) primers and one long‐primer random amplified polymorphic DNA (LP‐RAPD) primer. Collections from the Red River Valley of North Dakota and Minnesota, sampled in 1964 and 2000, represented A. fatua populations before and after intensive exposure to herbicides. A 1995 collection from south‐west North Dakota represented A. fatua exposed to low herbicide selection. Despite differences in years of herbicide exposure among collections, both HR and HS populations from every collection maintained nearly similar levels of ISSR and RAPD diversity. Genetic differentiation among populations (GST) varied from 11% to 13% among HR populations and from 9% to 16% among HS populations, indicating that 84–91% of total variation remained within HS or within HR populations. Minimal difference in gene diversity between HR and HS is consistent with multiple origins of resistance, where HR A. fatua most likely evolved from diverse founding individuals.