bluuebunny/crossref_metadata_2025_split huggingface dataset:
The importance of sward architectural complexity in structuring predatory and phytophagous invertebrate assemblages
Authors: WOODCOCK B. A. , POTTS S. G. , WESTBURY D. B. , RAMSAY A. J. , LAMBERT M. , HARRIS S. J. , BROWN V. K. 
Published: April 2007

Abstract 1. Although the importance of plant community assemblages in structuring invertebrate assemblages is well known, the role that architectural complexity plays is less well understood. In particular, direct empirical data for a range of invertebrate taxa showing how functional groups respond to plant architecture is largely absent from the literature.2. The significance of sward architectural complexity in determining the species richness of predatory and phytophagous functional groups of spiders, beetles, and true bugs, sampled from 135 field margin plots over 2 years was tested. The present study compares the relative importance of sward architectural complexity to that of plant community assemblage.3. Sward architectural complexity was found to be a determinant of species richness for all phytophagous and predatory functional groups. When individual species responses were investigated, 62.5% of the spider and beetle species, and 50.0% of the true bugs responded to sward architectural complexity.4. Interactions between sward architectural complexity and plant community assemblage indicate that the number of invertebrate species supported by the plant community alone could be increased by modification of sward architecture. Management practices could therefore play a key role in diversifying the architectural structure of existing floral assemblages for the benefit of invertebrate assemblages.5. The contrasting effects of sward architecture on invertebrate functional groups characterised by either direct (phytophagous species) or indirect (predatory species) dependence on plant communities is discussed. It is suggested that for phytophagous taxa, plant community assemblage alone is likely to be insufficient to ensure successful species colonisation or persistence without appropriate development of sward architecture.
Indirect genetic effects from ecological interactions in Arabidopsis thaliana
Authors: MUTIC JOSHUA J. , WOLF JASON B. 
Published: April 2007

AbstractIndirect genetic effects arise when genes expressed in one individual affect the expression of traits in other individuals. The importance of indirect genetic effects has been recognized for a diversity of evolutionary processes including kin selection, sexual selection, community structure and multilevel selection, but data regarding their genetic architecture and prevalence throughout the genome remain scarce, especially for interactions between unrelated individuals. Using a set of 411 Bay‐0 × Shahdara Arabidopsis recombinant inbred lines grown with Landsberg neighbours, we examined quantitative trait loci (QTL) having direct and indirect effects on size, developmental, and fitness related traits. Using an interval mapping approach, we identified 15 QTL with direct effects and found that 13 of these QTL had significant indirect effects on trait expression in neighbouring plants. These results suggest widespread pleiotropy, as nearly all direct effect QTL have associated pleiotropic indirect effects. Paradoxically, most indirect effects were of the same sign as direct effects, creating a pattern of nearly universal positive pleiotropy that makes most covariances between direct and indirect effects positive. These results are consistent with a complex genetic basis for intraspecific interactions, but suggest that interactions between neighbouring plants are largely positive, rather than negative as would be expected for competition. In addition to their evolutionary and ecological importance, these pleiotropic relationships between DGE and IGE loci have implications for quantitative genetic studies of natural populations as well as experimental design considerations. Additionally, studies that ignore IGEs may over‐ or underestimate quantitative genetic parameters, as well as the effect of and variance contributed by QTL.
Genetic heterogeneity among intertidal habitats in the flat periwinkle, Littorina obtusata
Authors: SCHMIDT PAUL S. , PHIFER‐RIXEY MEGAN , TAYLOR GRAEME M. , CHRISTNER JOHN 
Published: April 2007

AbstractComparisons among patterns exhibited by functionally distinct genetic markers have been widely used to infer the impacts of demography and selection in structuring genetic variation in natural populations. However, such multilocus comparisons remain an indirect evaluation of selection at particular candidate loci; ideally, the identification of a candidate gene by comparative genetic methodologies should be complemented by functional analyses and experimental manipulations of genotypes in the laboratory or field. We examined genotype frequency variation among replicated intertidal habitats at two spatial scales in the grazing snail Littorina obtusata. Both of the candidate allozyme markers varied predictably with environment, and these patterns were consistent at both spatial scales. Three of four reference loci were spatially homogeneous, but one microsatellite exhibited significant structure at both geographical and mesoscales. To initiate a direct examination of whether the observed genotype frequency variation at one of the candidate markers, mannose‐6‐phosphate isomerase (MPI), was impacted by differential survivorship of genotypes, we conducted a series of laboratory‐based thermal stress assays using snails from two geographically disparate source populations. When snails were exposed to bouts of thermal/desiccation stress, patterns of mortality were nonrandom with respect to MPI genotype. Furthermore, patterns of mortality in the laboratory manipulation coincided with the observed distribution of genotypes in the field. The data suggest the operation of selection at the Mpi or a linked locus, but functional studies and further experimentation are required to establish the relationship between MPI genotype and fitness across heterogeneous intertidal environments.
The genetic basis of adaptive pigmentation variation in Drosophila melanogaster
Authors: POOL JOHN E. , AQUADRO CHARLES F. 
Published: April 2007

AbstractIn a broad survey of Drosophila melanogaster population samples, levels of abdominal pigmentation were found to be highly variable and geographically differentiated. A strong positive correlation was found between dark pigmentation and high altitude, suggesting adaptation to specific environments. DNA sequence polymorphism at the candidate gene ebony revealed a clear association with the pigmentation of homozygous third chromosome lines. The darkest lines sequenced had nearly identical haplotypes spanning 14.5 kb upstream of the protein‐coding exons of ebony. Thus, natural selection may have elevated the frequency of an allele that confers dark abdominal pigmentation by influencing the regulation of ebony.
Self‐compatibility in Brassica napus is caused by independent mutations in S‐locus genes
Authors: Okamoto Shunsuke , Odashima Masashi , Fujimoto Ryo , Sato Yutaka , Kitashiba Hiroyasu , Nishio Takeshi 
Published: April 2007

Summary Brassica napus is an amphidiploid species with the A genome from Brassica rapa and the C genome from Brassica oleracea. Although B. rapa, B. oleracea and artificially synthesized amphidiploids with the AC genome are self‐incompatible, B. napus is self‐compatible. Six S genotypes were identified in B. napus, five of which had class I S haplotypes from one species and a class II S haplotype from the other species, and mutations causing self‐compatibility were identified in three of these S genotypes. The most predominant S genotype (BnS‐1;BnS‐6), which is that of cv. ‘Westar’, had a class I S haplotype similar to B. rapa S‐47 (BrS‐47) and a class II S haplotype similar to B. oleracea S‐15 (BoS‐15). The stigmas of ‘Westar’ rejected the pollen grains of both BrS‐47 and BoS‐15, while reciprocal crossings were compatible. Insertion of a DNA fragment of about 3.6 kb was found in the promoter region of the SP11/SCR allele of BnS‐1, and transcripts of SP11/SCR were not detected in ‘Westar’. The nucleotide sequence of the SP11 genomic DNA of BnS‐6 was 100% identical to that of SP11 of BoS‐15. Class I SP11 alleles from one species showed dominance over class II SP11 alleles from the other species in artificially synthesized B. napus lines, suggesting that the non‐functional dominant SP11 allele suppressed the expression of the recessive SP11 allele in ‘Westar’. Two other S genotypes in B. napus also had non‐functional class I S haplotypes together with recessive BnS‐6. These observations suggest independent origins of self‐compatibility in B. napus.
Altered expression of plant lysyl tRNA synthetase promotes tRNA misacylation and translational recoding of lysine
Authors: Wu Xing Rong , Kenzior Alexander , Willmot David , Scanlon Sarah , Chen Zhihong , Topin Andrey , He Shao Hua , Acevedo Ashley , Folk William R. 
Published: April 2007

SummaryThe Arabidopsis thaliana lysyl tRNA synthetase (AtKRS) structurally and functionally resembles the well‐characterized prokaryotic class IIb KRS, including the propensity to aminoacylate tRNALys with suboptimal identity elements, as well as non‐cognate tRNAs. Transient expression of AtKRS in carrot cells promotes aminoacylation of such tRNAs in vivo and translational recoding of lysine at nonsense codons. Stable expression of AtKRS in Zea mays causes translational recoding of lysine into zeins, significantly enriching the lysine content of grain.
Sulfite oxidase protects plants against sulfur dioxide toxicity
Authors: Brychkova Galina , Xia Zongliang , Yang Guohua , Yesbergenova Zhazira , Zhang Zhili , Davydov Olga , Fluhr Robert , Sagi Moshe 
Published: April 2007

SummaryThe gaseous pollutant SO2 readily reacts with water to form sulfite that impacts deleteriously on animal and plant health. By modulating the level of sulfite oxidase (SO) that catalyzes the transformation of sulfites to the non‐toxic sulfate, we show that Arabidopsis and tomato plants can be rendered resistant or susceptible to SO2/sulfite. Plants in which sulfite oxidase expression was abrogated by RNA interference (RNAi) accumulated relatively less sulfate after SO2 application and showed enhanced induction of senescence and wounding‐associated transcripts, leaf necrosis and chlorophyll bleaching. In contrast, SO overexpression lines accumulated relatively more sulfate and showed little or no necrosis after SO2 application. The transcript of sulfite reductase, a chloroplast‐localized enzyme that reduces sulfites to sulfides, was shown to be rapidly induced by SO2 in a sulfite oxidase‐dependent manner. Transcripts of other sulfite‐requiring enzymatic activities such as mercaptopyruvate sulfur transferases and UDP‐sulfoquinovose synthase 1 were induced later and to a lesser extent, whereas SO was constitutively expressed and was not significantly induced by SO2. The results imply that plants can utilize sulfite oxidase in a sulfite oxidative pathway to cope with sulfite overflow.
From seedling to mature plant: Arabidopsis plastidial genome copy number, RNA accumulation and transcription are differentially regulated during leaf development
Authors: Zoschke Reimo , Liere Karsten , Börner Thomas 
Published: April 2007

SummaryLittle is known about DNA and RNA metabolism during leaf development and aging in the model organism Arabidopsis. Therefore we examined the nuclear and plastidial DNA content of tissue ranging in age from 2‐day‐old cotyledons to 37‐day‐old senescent rosette leaves. Flow‐cytometric analysis showed an increase in nuclear DNA ploidy levels of up to 128 genome copies per nucleus in older leaves. The copy numbers of nuclear 18S‐rRNA genes were determined to be 700 ± 60 per haploid genome. Adjusted to the average level of nuclear DNA polyploidism per cell, plastome copy numbers varied from about 1000 to 1700 per cell without significant variation during development from young to old rosette leaves. The transcription activity of all studied plastid genes was significantly reduced in older rosette leaves in comparison to that in young leaves. In contrast, levels of plastidial transcript accumulation showed different patterns. In the case of psbA, transcripts accumulated to even higher levels in older leaves, indicating that differential regulation of plastidial gene expression occurs during leaf development. Examination of promoter activity from clpP and rrn16 genes by primer extension analyses revealed that two RNA polymerases (NEP and PEP) transcribe these genes in cotyledons as well as in young and senescent leaves. However, PEP may have a more prominent role in older rosette leaves than in young cotyledons. We conclude that in cotyledons or leaves of different ages plastidial gene expression is regulated at the transcriptional and post‐transcriptional levels, but not by plastome copy number.
Arabidopsis thaliana plants possess a specific farnesylcysteine lyase that is involved in detoxification and recycling of farnesylcysteine
Authors: Crowell Dring N. , Huizinga David H. , Deem Angela K. , Trobaugh Corey , Denton Ryan , Sen Stephanie E. 
Published: April 2007

SummaryIn plants, prenylated proteins are involved in actin organization, calcium‐mediated signal transduction, and many other biological processes. Arabidopsis thaliana mutants lacking functional protein prenyltransferase genes have also revealed roles for prenylated proteins in phytohormone signaling and meristem development. However, to date, the turnover of prenylated plant proteins and the fate of the prenylcysteine (PC) residue have not been described. We have detected an enzyme activity in Arabidopsis plants that metabolizes farnesylcysteine (FC) to farnesal, which is subsequently reduced to farnesol. Unlike its mammalian ortholog, Arabidopsis FC lyase exhibits specificity for FC over geranylgeranylcysteine (GGC), and recognizes N‐acetyl‐FC (AFC). FC lyase is encoded by a gene on chromosome 5 of the Arabidopsis genome (FCLY, At5g63910) and is ubiquitously expressed in Arabidopsis tissues and organs. Furthermore, T‐DNA insertions into the FCLY gene cause significant decreases in FC lyase activity and an enhanced response to abscisic acid (ABA) in seed germination assays. The effects of FCLY mutations on ABA sensitivity are even greater in the presence of exogenous FC. These data suggest that plants possess a specific FC detoxification and recycling pathway.
Prey Size Selection under Simultaneous Choice by the Broad‐Headed Skink (Eumeces laticeps)
Authors: Cooper William E. , Anderson Roger A. , Frederick William G. 
Published: April 2007

AbstractDiet selection among several prey types present in a dense aggregation, permitting a predator to become satiated without changing patches, may be important for predators that can eat many small prey items in a single bout. Choice in this scenario differs from that in optimal foraging models for sequential diet choice model and simultaneous choice models when travel time between patches is needed. Furthermore, satiation and depletion effects may be important in dense prey aggregations. We predicted that in dense prey aggregations, predators should eat the most profitable prey first, switching to smaller prey as larger ones become depleted and predators become satiated, and that prey below some minimum profitability should be rejected. When large numbers of prey of varying sizes were presented simultaneously, broad‐headed skinks (Eumeces laticeps) preferentially consumed large crickets, ate some medium‐sized crickets late in ingestion sequences, but ate no small crickets. Prey depletion, with selection of the currently most profitable prey type, appears to account for much of observed prey switching, and satiation may contribute. When four crickets of each of four sizes were presented, lizards ate largest first, then medium‐sized. Some then ate small crickets, but none ate very small crickets. These observations and exclusion of small crickets from the diet by many lizards when larger ones were unavailable support the predictions. In tests with three sizes of juvenile mice presented singly, the smallest were attacked at shortest latency and eaten, medium‐sized mice were attacked at greater latency but could not be subdued, and large mice were not attacked. These data suggest that as prey become too large to subdue and eat readily, profitability declines until they are excluded from the diet. Unsuccessful attacks on medium‐sized mice suggest that lizards had to learn their own capabilities with respect to a novel prey type.
Geographic Variation in the Long Calls of Male Orangutans (Pongo spp.)
Authors: Delgado Roberto A. 
Published: April 2007

AbstractRelatively few data exist on population differences in the vocal behavior of mammals. Geographic variation in calls is of special interest because of the implications for resolving evolutionary and behavioral questions. For example, information on geographic variation in vocalizations complements morphological and molecular data used to infer phylogenetic relationships and provides evidence for the mechanisms underlying call development. A quantitative acoustic analysis of orangutan long calls was undertaken, comparing flanged adult males from four geographically distinct sites across Borneo and Sumatra, revealing consistent differences among the calls of individuals. Long calls produced by orangutans from the four sites in Borneo and Sumatra differ in quantitative acoustic measures. Discriminant function analysis reveals that acoustic variables can be used in combination to assign calls to the correct individual, site and island at rates higher than that expected by chance. Specifically, four acoustic parameters proved reliable for distinguishing among the individuals, between sites, and across the two islands that arguably represent populations from separate species or subspecies. Although Bornean and Sumatran long calls share a repetitive structure and show similar call rates (0.100–0.500 LCs/h) and maximum frequency bands (0.400–1.500 kHz), they differ significantly in the number of pulses per call, call speed, call duration, bandwidth, pulse duration, and dominant frequency. Strong consistency in these acoustic parameters is also seen among males within sites and the observed variation may allow for individual recognition. Individual identification by call structure presumably benefits dispersed orangutans, where individuals characteristically forage independently and both encounters and interactions with signaling males are highly variable and largely dependent on context. Acoustic recognition of callers facilitates the choice of which males to join or avoid, thus allowing receivers to manipulate potential costs and benefits of association.
Female Meadow Voles, Microtus pennsylvanicus, Experience a Reduction in Copulatory Behavior During Postpartum Estrus
Authors: DelBarco‐Trillo Javier , Ferkin Michael H. 
Published: April 2007

AbstractIn many small mammalian species, females undergo postpartum estrus (PPE), mate, and become pregnant soon after delivering a litter. Mating during PPE implies a trade‐off between attending to the new litter and leaving that litter to mate. We tested the hypothesis that copulatory behavior is faster when a female mates during PPE than when it mates outside of PPE, during male‐induced estrus (MIE), a time when it is not lactating. We compared several variables of copulatory behavior in female meadow vole mating during both PPE and MIE. Females in PPE received significantly fewer intromissions, with shorter intervals between intromissions. Each ejaculatory series was also shorter for females in PPE. As a consequence, the total amount of time devoted to copulation was much shorter for females in PPE than for those in MIE. These data support the hypothesis that female meadow voles are able to reduce their copulatory behavior during PPE.
The Payoff of Fighting in House Crickets: Motivational Asymmetry Increases Male Aggression and Mating Success
Authors: Brown William D. , Chimenti Andrew J. , Siebert Joseph R. 
Published: April 2007

AbstractMotivational asymmetry caused by differences in subjective resource value is a key component of strategic models of aggression. We study the role of motivational asymmetry in determining differential aggression and mating success of male house crickets,Acheta domesticus. We also assess the extent to which mating differences associated with motivational asymmetry are due to direct male–male fighting vs. male–female interactions. We manipulated male motivation to compete for a mating opportunity by providing males with either no access or nightly access to females for 4 d prior to the experiment. As predicted, when males from each treatment had to compete for the female, those with lower prior access were more aggressive and mated more often. In contrast, when males from each treatment were paired individually with females, there was no significant difference in the frequencies with which they pursued, courted or mated with females. We also found no evidence for female choice based on motivational asymmetry; the rate of successful courtship did not differ between treatments. We conclude that prior mate encounter rate can generate motivational asymmetry, leading to differential mating success mediated by direct male–male aggression.
Phylogenetic study of benthic, spine‐bearing prorocentroids, including Prorocentrum fukuyoi sp. nov.
Authors: Murray Shauna , Nagahama Yukio , Fukuyo Yasuwo 
Published: April 2007

SUMMARYSpecies of prorocentroid dinoflagellates are common in marine benthic sediment and epibenthic habitats, as well as in planktonic habitats. Marine planktonic prorocentroids typically possess a small spine in the apical region. In this study, we describe a new, potentially widely distributed benthic species of Prorocentrum, P. fukuyoi sp. nov., from tidal sand habitats in several sites in Australia and from central Japan. This species was found to possess an apical spine or flange and was sister species to P. emarginatum. We analyzed the phylogeny of the group including this new species, based on large subunit (LSU) rDNA sequences. The genus contained a high level of divergence in LSU rDNA, in some cases among sister taxa. P. fukuyoi and P. emarginatum were found to be most closely related to a clade of generally planktonic taxa. Several morphological features may constitute more informative synapomorphies than habitat in distinguishing clades of prorocentroid species.
Seasonal variations in thalli and carrageenan composition of Gigartina pistillata (Gmelin) Stackhouse (Rhodophyta, Gigartinales) harvested along the Atlantic coast of Morocco
Authors: Amimi Abdellah , Mouradi Aziza , Bennasser Laila , Givernaud Thiery 
Published: April 2007

SUMMARYThe biology and biochemistry of Gigartina pistillata (Gmelin) Stackhouse collected monthly at Nation Beach (Morocco), was studied during one year. The biological study showed one period of active growth from April to July. The thallus composition was quite stable during the major part of the year. The dry matter was maximum in May and August and minimum in January. The maximum carrageenan content occurred in June and September (about 37%) and the minimum carrageenan content occurred in February (19.0%). The total nitrogen content varied significantly, with a maximum in January (1.98%) and a minimum in August (0.7%). The ash content was significant (23–32%) with a maximum in August and a minimum in May. The carrageenan extracted from natural populations of Gigartina pistillata was a mixture of lambda‐type and kappa‐type carrageenans. The 3,6‐anhydrogalactose varied between 4.5 mol% in June to 25 mol% in February. For industrial applications the extract could be considered as a lambda‐type. The best period for harvest of G. pistillata in Morocco is between July and August when biomass and viscosity are at their maximum. A relationship between the physical characteristics of G. pistillata carrageenans and its seasonal cycle was deduced.