bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uptake of Bt endotoxins by nontarget herbivores and higher order arthropod predators: molecular evidence from a transgenic corn agroecosystem
Authors: HARWOOD JAMES D. , WALLIN WILLIAM G. , OBRYCKI JOHN J. 
Published: July 2005

AbstractThe planting of transgenic crops expressing Bacillus thuringiensis endotoxins is widespread throughout the world; the prolific increase in their application exposes nontarget organisms to toxins designed to control pests. To date, studies have focused upon the effects of Bt endotoxins on specific herbivores and detritivores, without consideration of their persistence within arthropod food webs. Here, we report the first quantitative field evaluation of levels of Bt endotoxin within nontarget herbivores and the uptake by higher order arthropods. Antibody‐based assays indicated significant quantities of detectable Cry1Ab endotoxin within nontarget herbivores which feed on transgenic corn (including the corn flea beetle, Chaetocnema pulicaria, Japanese beetle, Popillia japonica and southern corn rootworm, Diabrotica undecimpunctata howardi). Furthermore, arthropod predators (Coccinellidae, Araneae, and Nabidae) collected from these agroecosystems also contained significant quantities of Cry1Ab endotoxin indicating its movement into higher trophic levels. This uptake by predators is likely to have occurred by direct feeding on plant material (in predators which are facultatively phytophagous) or the consumption of arthropod prey which contained these proteins. These data indicate that long‐term exposure to insecticidal toxins occurs in the field. These levels of exposure should therefore be considered during future risk assessments of transgenic crops to nontarget herbivores and arthropod predators.
Enterobacteria‐mediated nitrogen fixation in natural populations of the fruit fly Ceratitis capitata
Authors: BEHAR A. , YUVAL B. , JURKEVITCH E. 
Published: July 2005

AbstractNitrogen, although abundant in the atmosphere, is paradoxically a limited resource for multicellular organisms. In the Animalia, biological nitrogen fixation has solely been demonstrated in termites. We found that all individuals of field‐collected Mediterranean fruit flies (Ceratitis capitata) harbour large diazotrophic enterobacterial populations that express dinitrogen reductase in the gut. Moreover, nitrogen fixation was demonstrated in isolated guts and in live flies and may significantly contribute to the fly's nitrogen intake. The presence of similar bacterial consortia in additional insect orders suggests that nitrogen fixation occurs in vast pools of terrestrial insects. On such a large scale, this phenomenon may have a considerable impact on the nitrogen cycle.
Impact of ice ages on circumpolar molecular diversity: insights from an ecological key species
Authors: ALSOS I. G. , ENGELSKJØN T. , GIELLY L. , TABERLET P. , BROCHMANN C. 
Published: July 2005

AbstractWe address the impact of the ice age cycles on intraspecific cpDNA diversity, for the first time on the full circumboreal‐circumarctic scale. The bird‐dispersed bog bilberry (or arctic blueberry, Vaccinium uliginosum) is a key component of northern ecosystems and is here used to assess diversity in previously glaciated vs. unglaciated areas and the importance of Beringia as a refugium and source for interglacial expansion. Eighteen chloroplast DNA haplotypes were observed in and among 122 populations, grouping into three main lineages which probably diverged before, and thus were affected more or less independently by, all major glaciations. The boreal ‘Amphi‐Atlantic lineage’ included one haplotype occurring throughout northern Europe and one occurring in eastern North America, suggesting expansion from at least two bottlenecked, glacial refugium populations. The boreal ‘Beringian lineage’ included seven haplotypes restricted to Beringia and the Pacific coast of USA. The ‘Arctic‐Alpine lineage’ included nine haplotypes, one of them fully circumpolar. This lineage was unexpectedly diverse, also in previously glaciated areas, suggesting that it thrived on the vast tundras during the ice ages and recolonized deglaciated terrain over long distances. Its largest area of persistence during glaciations was probably situated in the north, stretching from Beringia and far into Eurasia, and it probably also survived the last glaciation in southern mountain ranges. Although Beringia apparently was important for the initial divergence and expansion of V. uliginosum as well as for continuous survival of both the Beringian and Arctic‐Alpine lineages during all ice ages, this region played a minor role as a source for later interglacial expansions.
Population genetic structure in migratory sandhill cranes and the role of Pleistocene glaciations
Authors: JONES KENNETH L. , KRAPU GARY L. , BRANDT DAVID A. , ASHLEY MARY V. 
Published: July 2005

AbstractPrevious studies of migratory sandhill cranes (Grus canadensis) have made significant progress explaining evolution of this group at the species scale, but have been unsuccessful in explaining the geographically partitioned variation in morphology seen on the population scale. The objectives of this study were to assess the population structure and gene flow patterns among migratory sandhill cranes using microsatellite DNA genotypes and mitochondrial DNA haplotypes of a large sample of individuals across three populations. In particular, we were interested in evaluating the roles of Pleistocene glaciation events and postglaciation gene flow in shaping the present‐day population structure. Our results indicate substantial gene flow across regions of the Midcontinental population that are geographically adjacent, suggesting that gene flow for most of the region follows an isolation‐by‐distance model. Male‐mediated gene flow and strong female philopatry may explain the differing patterns of nuclear and mitochondrial variation. Taken in context with precise geographical information on breeding locations, the morphologic and microsatellite DNA variation shows a gradation from the Arctic‐nesting subspeciesG. c. canadensisto the nonArctic subspeciesG. c. tabida. Analogous to other Arctic‐nesting birds, it is probable that the population structure seen in Midcontinental sandhill cranes reflects the result of postglacial secondary contact. Our data suggest that subspecies of migratory sandhills experience significant gene flow and therefore do not represent distinct and independent genetic entities.
Strong spatial genetic structure in peripheral but not core populations of Sitka spruce [Picea sitchensis (Bong.) Carr.]
Authors: GAPARE WASHINGTON J. , AITKEN SALLY N. 
Published: July 2005

AbstractWe examined spatial genetic structure within eight populations of Sitka spruce classified as core or peripheral based on ecological niche, and continuous or disjunct based on species distribution. In each population, 200 trees were spatially mapped and genotyped for eight cDNA‐based sequence tagged site (STS) codominant markers. Spatial autocorrelation was assessed by estimating pij, the average co‐ancestry coefficient, between individuals within distance intervals. The distribution of alleles and genotypes within core populations was almost random, with nonsignificant co‐ancestry values among trees as close as 50 m in core populations. In contrast, the distribution of alleles and genotypes within peripheral populations revealed an aggregation of similar multilocus genotypes, with co‐ancestry values greater than 0.20 among trees up to 50 m apart and significant, positive values between trees up to 500 m. The relatively high density of reproductive adults in core populations may lead to highly overlapping seed shadows that limit development of spatial genetic structure. However, in peripheral populations with a lower density of adults, the distribution of alleles and genotypes was highly structured, likely due to offspring establishment near maternal trees and subsequent biparental inbreeding, as well as more recent population establishment at the leading edge of post‐Pleistocene range expansion. Conserving genetic diversity in peripheral populations may require larger reserves for in situ conservation than required in core populations. These data on spatial genetic structure can be used to provide guidance for sampling strategies for both ex situ conservation and research collections.
Clone identification and clonal structure of the European aspen (Populus tremula)
Authors: SUVANTO LEENA I. , LATVA‐KARJANMAA TARJA B. 
Published: July 2005

AbstractThe European aspen (Populus tremula) is thought to reproduce mostly asexually. Thus aspen forms clones, in which several ramets belong to one genetically defined genet. We compared the clonal structure of aspen in old‐growth and managed forests in southern and northeastern Finland. Clones were identified using morphological characters and nine microsatellite loci originally developed for Populus tremuloides. There were more clones identified by microsatellites than morphotypes both in old‐growth and managed forest. The average size of the clones was only 2.3 ramets and most clones (70%) consisted of just one ramet. The size of the clones showed no difference between managed and old‐growth forests or between northeastern and southern Finland. The small size of the clones suggests that most of them are relatively young. Therefore, sexual reproduction may be more common than previously thought. There was an aggregated spatial genetic structure as measured by Moran's I (0–10 m) and by co‐ancestry (ρij, 0–20 m). Low level of co‐ancestry can be explained by relatively unrestricted gene flow, the important role of disturbance in reproduction, and/or local selection.
Genetic structure of the cyclic fossorial water vole (Arvicola terrestris): landscape and demographic influences
Authors: BERTHIER K. , GALAN M. , FOLTÊTE J. C. , CHARBONNEL N. , COSSON J. F. 
Published: July 2005

AbstractGenetic structure can be strongly affected by landscape features and variation through time and space of demographic parameters such as population size and migration rate. The fossorial water vole (Arvicola terrestris) is a cyclic species characterized by large demographic fluctuations over short periods of time. The outbreaks do not occur everywhere at the same time but spread as a wave at a regional scale. This leads to a pattern of large areas (i.e. some hundreds of km2), each with different vole abundances, at any given time. Here, we describe the abundance and genetic structures in populations of the fossorial water vole. We use the data to try to understand how landscape and demographic features act to shape the genetic structure. The spatial variability of vole abundance was assessed from surface indices, collected in spring 2002 (April) in eastern central France. Genetic variability was analysed using eight microsatellite loci at 23 localities sampled between October 2001 and April 2002. We found some congruence between abundance and genetic structures. At a regional scale, the genetic disruptions were associated with both sharp relief and transition between an area of low abundance and another of high abundance. At a local scale, we observed a variation of the isolation‐by‐distance pattern according to the abundance level of vole populations. From these results we suggest that the dispersal pattern in cyclic rodent populations varies throughout the demographic cycle.
Within‐population spatial genetic structure, neighbourhood size and clonal subrange in the seagrass Cymodocea nodosa
Authors: ALBERTO FILIPE , GOUVEIA LICÍNIA , ARNAUD‐HAOND SOPHIE , PÉREZ‐LLORÉNS JOSÉ L. , DUARTE CARLOS M. , SERRÃO ESTER A. 
Published: July 2005

AbstractThe extent of clonality within populations strongly influences their spatial genetic structure (SGS), yet this is hardly ever thoroughly analysed. We employed spatial autocorrelation analysis to study effects of sexual and clonal reproduction on dispersal of the dioecious seagrass Cymodocea nodosa. Analyses were performed both at genet level (i.e. excluding clonal repeats) and at ramet level. Clonal structure was characterized by the clonal subrange, a spatial measure of the linear limits where clonality still affects SGS. We show that the clonal subrange is equivalent to the distance where the probability of clonal identity approaches zero. This combined approach was applied to two meadows with different levels of disturbance, Cadiz (stable) and Alfacs (disturbed). Genotypic richness, the proportion of the sample representing distinct genotypes, was moderate (0.38 Cadiz, 0.46 Alfacs) mostly due to dominance of a few clones. Expected heterozygosities were comparable to those found in other clonal plants. SGS analyses at the genet level revealed extremely restricted gene dispersal in Cadiz (Sp = 0.052, a statistic reflecting the decrease of pairwise kinship with distance), the strongest SGS found for seagrass species, comparable only to values for selfing herbaceous land plants. At Cadiz the clonal subrange extended across shorter distances (20–25 m) than in Alfacs (30–35 m). Comparisons of sexual and vegetative components of gene dispersal suggest that, as a dispersal vector within meadows, clonal spread is at least as important as sexual reproduction. The restricted dispersal and SGS pattern in both meadows indicates that the species follows a repeated seedling recruitment strategy.
F‐statistics of clonal diploids structured in numerous demes
Authors: DE MEEÛS THIERRY , BALLOUX FRANÇOIS 
Published: July 2005

AbstractThe expected apportionment of genetic diversity in diploid clonal organisms structured in numerous subpopulations is explored. Under the specific assumptions considered, corresponding, for instance, to clonal pathogens infecting a large number of hosts, the co‐ancestry between individuals within subpopulations is the only nontrivial quantity. Thus the population structure can be fully described either by FST or FIS, as FST = –FIS/(1 − FIS). We show that, for most of the parameter space considered, including simulations where equilibrium is not reached and/or where homoplasy is high, the number of effective migrants is most accurately estimated as Nm = –(1 + FIS)/4FIS. We further propose a criterion to test for the absence of cryptic sexual reproduction based on the F‐statistics FIS and FST, which is applied to three previously published empirical data sets.
Impact of AIDS on Family Composition, Welfare, and Investment: Evidence from Uganda*
Authors: Deininger Klaus , Crommelynck Anja , Kempaka Gloria 
Published: July 2005

AbstractAlthough availability of quantitative information on the extent of HIV/AIDS in Africa is improving, the socio‐economic implications of the epidemic remain poorly understood. This paper explores this issue for Uganda focusing on households who received foster children between 1992 and 2000, a phenomenon that affected more than 15% of households. The authors find that addition of a foster child resulted in significant reductions of per capita consumption, income, and household investment which were more pronounced for the poor. Initial disadvantages in foster children's access to education for this group were overcome in the course of UPE implementation, while new inequalities have emerged in access to health services. Foster children's ability to access services will thus be affected by the broader policy environment as well as programs more specifically targeted at this group.
City CPI Convergence in Mexico
Authors: Sonora Robert J. 
Published: July 2005

AbstractThis paper tests the purchasing power parity hypothesis within a single developing country currency area: Mexico. This work stems from research in comparing price movements across countries and a growing literature on price dynamics within a single currency area. The author uses city Consumer Price Index data for 34 cities in Mexico over the period 1982–2000. He followed the standard procedure of testing for I(1) processes in relative city prices, or city real exchange rates, using univariate and panel unit root tests. The main results of the paper are: First, Mexican city relative prices are stationary—the data rejects the hypothesis that city real exchange rates contain a random walk, but only using panel unit root techniques. Finally, regional demand and supply homogeneity implies stronger evidence for price parity within regions, while there is considerable evidence of regional price convergence, regional homogeneity does not guarantee faster convergence.
The Government's Foreign Debt in the Argentine Crisis
Authors: Kitano Shigeto 
Published: July 2005

AbstractThough the government had adopted a currency board regime since 1991, the Argentine economy suffered a currency crisis in 2002. It is shown that currency crises can arise, even under currency board systems in which the central bank has enough international reserves to respond to arbitrary withdrawals by individuals. The model implies that a government's rapid accumulation of foreign debt should be included as a major predictor of currency crises.
Start‐up Capital, Microenterprises and Technical Efficiency in Mexico
Authors: Hernández‐Trillo Fausto , Pagán José A. , Paxton Julia 
Published: July 2005

AbstractAccess to adequate start‐up capital has been identified as an important deterrent to microenteprise development and growth. Using firm level data from Mexico's National Survey of Microenterprises, we estimate a stochastic frontier production function with inefficiency effects related to the main sources of start‐up capital. Microenterprises utilizing bank loans, carryover business capital, moneylenders and credit from clients and suppliers are more technically efficient than those relying on family, friends and on own financial sources. Bank loans led to the highest degree of technical efficiency, indicating a well‐functioning screening process despite information asymmetries. Banks tend to offer the largest average loan size with the longest terms which are significant factors in allowing microentrepreneurs to overcome financing constraints.
Gene Polymorphism Association Studies in Dialysis: The Nutrition‐Inflammation Axis
Authors: Jaber Bertrand L. , Balakrishnan Vaidyanathapuram S. , Stenvinkel Peter , Pecoits‐Filho Roberto , Lindholm Bengt ,   for the DialGene Consortium
Published: July 2005

ABSTRACTAlthough traditional risk factors for cardiovascular disease are common in dialysis patients, they alone cannot explain the unacceptably high prevalence of vascular disease in this patient group. Much recent interest has therefore focused on the role of various nontraditional cardiovascular risk factors, such as inflammation, wasting, obesity, vascular calcification, and oxidative stress. In addition, genetic factors such as single nucleotide polymorphisms (SNPs) may significantly influence the immune response, the levels of inflammatory markers and body composition, as well as the prevalence of vascular calcification in this patient group. While genetic variations in the tumor necrosis factor (TNF)‐α−308 and interleukin (IL)‐10 −1082 SNPs seem to be consistently associated with adverse clinical outcome in end‐stage renal disease (ESRD) patients, the results regarding genetic variations in the IL‐6 gene have been conflicting. To elucidate the respective role of DNA polymorphisms in the IL‐6 and C‐reactive protein (CRP) genes, as well as genes that encode vascular calcification inhibitors (such as fetuin‐A, matrix Gla protein, and osteoprotegerin), sufficiently powered studies are needed in which both the protein product and the specific phenotype are determined. In addition, polymorphisms in genes related to body composition may be excellent candidates for analysis in the ESRD population, since nutritional parameters are strongly associated with adverse events in these patients. It seems conceivable that in the future, prognostic or predictive multigene DNA assays (which allow a simultaneous and rapid assessment of multiple genetic variants) will provide nephrologists with a more precise approach for the identification of “high‐risk” ESRD patients and the development of accurate individualized treatment strategies.
Sumoylation modulates transcriptional activity of MITF in a promoter‐specific manner
Authors: Murakami Hideki , Arnheiter Heinz 
Published: July 2005

SummaryThe microphthalmia transcription factor MITF plays important roles in several cell lineages including retinal and neural crest‐derived pigment cells. Previous reports have shown that besides its regulation at the transcriptional level, MITF is also regulated post‐translationally by phosphorylation and ubiquitination which affect the protein's activity and stability. Here we demonstrate that in addition, MITF is modified in melanoma cells by small ubiquitin‐like modifier (SUMO). In vitro assays further show that sumoylation occurs at two lysine residues, K182 and K316, and depends on SUMO E1 activating enzyme (SAE I/SAE II) and E2 conjugating enzyme (Ubc9). Interestingly, MITF with double lysine 182/316 to arginine mutations, although displaying normal DNA binding, stability and nuclear localization, shows a substantial increase in the transcriptional stimulation of promoters containing multiple but not single MITF binding sites. MITF containing the double lysine‐to‐arginine substitution also shows enhanced cooperation with Sox10 on the Dct promoter. We conclude that SUMO modification of MITF regulates the protein's transcriptional activity especially with respect to synergistic activation. The results suggest that sumoylation plays a significant role among the multiple mechanisms that regulate MITF during development and in adulthood.
Novel expression patterns of Pax3/Pax7 in early trunk neural crest and its melanocyte and non‐melanocyte lineages in amniote embryos
Authors: Lacosta Ana Ma , Muniesa Pedro , Ruberte Jesús , Sarasa Manuel , Domínguez Luis 
Published: July 2005

SummaryNeural crest cells are considered a key vertebrate feature that is studied intensively because of their relevance to development and evolution. Here we report the expression of Pax7 in the dorsal non‐neural ectoderm and in the trunk neural crest of the early chick embryo. Pax7 is expressed in the trunk neural crest migrating along the ventral and dorsolateral routes. Pax7 is first downregulated in the neural crest‐derived neuronal precursors, secondly in the glial, and finally in the melanocyte precursors. Conserved developmental expression in the melanocyte lineage of both Pax3 and Pax7 was evidenced in chick and quail, but only Pax3 in mouse and rat.
Dopamine melanin‐loaded PC12 cells: a model for studies on pigmented neurons
Authors: Östergren Anna , Svensson Anne‐Lie , Lindquist Nils Gunnar , Brittebo Eva B. 
Published: July 2005

SummaryThe most conspicuous feature in idiopathic parkinsonism is the degeneration of pigmented neurons in the substantia nigra. A major problem for the study of the significance of neuromelanin for the development of parkinsonism is that common experimental animals lack neuromelanin in substantia nigra. The aim of this study was to develop an in vitro model that could be used to study the role of neuromelanin in chemically induced toxicity in dopaminergic cells. Cultured neuron‐like PC12 cells were exposed to synthetic dopamine melanin (0–1.0 mg/ml) for 48 h, resulting in uptake of dopamine melanin particles into the cells. The intracellular distribution of dopamine melanin granules was similar to that found in neuromelanin‐containing neurons. Dopamine melanin, up to 0.5 mg/ml, had negligible effects on ultrastructure, induction of the endoplasmic reticulum‐stress protein glucose regulating protein 78, activation of caspase‐3 and cell viability. The decreased cell viability in response to the cytotoxic peptide amyloid‐β25−35 was similar in melanin‐loaded cells and in control cells without melanin. The results of the studies suggest that melanin‐loaded PC12 cells can serve as an in vitro model for studies on the role of neuromelanin for the toxicity of chemicals, in particular neurotoxicants with melanin affinity, in pigmented neurons.