bluuebunny/crossref_metadata_2025_split huggingface dataset:
Corticotropin‐Releasing Hormone Immunoreactivity in Human T and B Cells and Macrophages: Colocalization With Arginine Vasopressin
Authors: Baker C. , Richards L. J. , Dayan C. M. , Jessop D. S. 
Published: October 2003

AbstractCorticotropin‐releasing hormone (CRH) and arginine vasopressin (AVP) are expressed in cells of the immune system where they exert immunomodulatory roles, but these neuropeptides are poorly characterized in human immune tissues. The aim of this study was to determine concentrations and distribution of CRH and AVP in nonactivated human peripheral blood mononuclear cells (PBMC). PBMC from normal human subjects were separated into enriched subpopulations of T and B cells and monocytes/macrophages by a magnetic bead/monoclonal antibody technique. CRH and AVP were measured in cell extracts by radioimmunoassay (RIA). CRH‐immunoreactivity (ir) ranged 0.24–0.8 fmol/million cells (n = 6 subjects) in T cell extracts, 0.4–2.7 fmol/million cells (n = 4) in B cells and 0.63–2.16 fmol/million cells (n = 4) in macrophages. AVP‐ir ranged 0.2–0.95 fmol/million cells in T cell extracts, <0.1–0.8 fmol/million cells in B cells and 0.14–3.19 fmol/million cells in macrophages. Reversed‐phase high‐performance liquid chromatography (HPLC) of T and B cell extracts revealed a peak of CRH‐ir which coeluted with synthetic CRH‐41; this peak was not present in macrophages. A second peak of CRH‐ir which eluted in a more hydrophobic position was observed in extracts of T and B cells and macrophages. This unidentified form of CRH‐ir is the predominant form of CRH‐ir in nonactivated human PBMC. This is the first study to demonstrate that CRH‐ir and AVP‐ir are colocalized within human T cells, B cells and monocytes/macrophages. We have confirmed observations of a variant form of CRH‐ir in human PBMC and show that this is the predominant form in macrophages and B cells whereas CRH‐ir, which coelutes with CRH(1–41) on HPLC, is present in significant amounts only in T cells. These data also confirm that CRH‐ir in human PBMC is not urocortin because the antiserum used in the CRH RIA does not bind to urocortin.
Acute Glucocorticoid Pretreatment Suppresses Stress‐Induced Hypothalamic‐Pituitary‐Adrenal Axis Hormone Secretion and Expression of Corticotropin‐Releasing Hormone hnRNA but Does Not Affect c‐fos mRNA or Fos Protein Expression in the Paraventricular Nucleus of the Hypothalamus
Authors: Ginsberg A. B. , Campeau S. , Day H. E. , Spencer R. L. 
Published: October 2003

AbstractCorticosterone regulates both basal and stress‐induced hypothalamic‐pituitary‐adrenal (HPA) axis activity in a negative‐feedback fashion. However, the cellular and molecular mechanisms of this negative feedback have yet to be explicitly characterized. By comparing stress‐induced c‐fos and corticotropin‐releasing hormone (CRH) expression in the paraventricular nucleus (PVN), we may be able to determine whether acute glucocorticoid treatment affects the net neural excitatory input to the PVN (represented primarily by c‐fos mRNA expression) or directly affects the ability of cells in the PVN to respond to that input (represented primarily by CRH hnRNA expression). In the following studies, we observed the effect of acute glucocorticoid (RU28362) treatment on subsequent HPA axis reactivity by measuring stress‐induced plasma hormone concentration [corticosterone and adrenocorticotropic hormone (ACTH)] and gene expression (c‐fos and CRH) in the PVN. First, we examined the dose–response relationship between systemically administered RU28362 (1–150 µg/kg, i.p) and suppression of the stress‐induced corticosterone response. We then confirmed central nervous system access of the maximally suppressive dose of RU28362 (150 µg/kg) by an ex vivo radioligand binding assay. RU28362 selectively occupied the majority of glucocorticoid receptors in the hippocampus and hypothalamus while having no effect on mineralocorticoid receptors. In separate studies, RU28362 (150 µg/kg) and corticosterone (5 mg/kg) were injected i.p. 1 h before restraint stress. Compared to vehicle‐treated controls, rats treated with RU28362 and corticosterone had substantially blunted stress‐induced corticosterone and ACTH production, respectively. Furthermore, treatment with RU28362 significantly blunted stress‐induced CRH hnRNA expression in the PVN. By contrast, neither RU28362 nor corticosterone treatment had an effect on stress‐induced neuronal activation as measured by c‐fos mRNA and its protein product in the PVN. This dissociation between c‐fos and CRH gene expression suggests that glucocorticoid suppression of HPA activity within this time‐frame is not a result of decreased excitatory neural input to the PVN, but instead depends on some direct effect of RU28362 on cells intrinsic to the HPA axis.
Melatonin Implants Disrupt Developmental Synchrony Regulated By Flexible Interval Timers
Authors: Gorman M. R. 
Published: October 2003

AbstractSiberian hamsters born into short daylengths near the end of the breeding season are reproductively inhibited from birth and delay gonadal maturation until the following spring. This vernal transition to a reproductive phenotype coincides with an abrupt increase in body weight, and both processes are triggered by an interval timing mechanism that becomes insensitive, or refractory, to short‐day inhibition. It was previously demonstrated that hamsters born into simulated natural photoperiods in early August became photorefractory at later ages than hamsters born into September photoperiods. As a consequence of flexibility in the duration programmed by the interval timer, development of seasonal birth cohorts was synchronous with respect to the calendar date simulated by laboratory photoperiod. In the present study, hamsters were born into simulated August or September photoperiods. Hamsters from each cohort were given removable constant release melatonin implants to reversibly obscure the neuroendocrine representation of daylength between 3 and 9 weeks or 9–15 weeks of age. When control hamsters were given beeswax capsules throughout, August‐born males were approximately 6 weeks older than September males at the onset of photorefractoriness as assessed by accelerated increases in body weight and testicular size. Females exhibited the same pattern in body weight. These measures were synchronized with respect to calendar date. Synchronization of cohorts was disrupted by melatonin capsules from 3–9 weeks of age but not by later implants. Melatonin implants altered synchronization by influencing the developmental trajectory of September‐born hamsters without influencing the August cohort. These results demonstrate that the function of the interval timer underlying photorefractoriness is influenced by photoperiod and by melatonin. The endogenous pattern of melatonin signals adjusts the duration measured by the interval timer to insure that developmental milestones of seasonal cohorts are synchronized with environmental conditions.
Genetic evidence for female‐biased dispersal in the bullfrog, Rana catesbeiana (Ranidae)
Authors: Austin James D. , Dávila José A. , Lougheed Stephen C. , Boag Peter T. 
Published: October 2003

AbstractSex‐biased dispersal is an important but unexplored area of amphibian ecology. We predicted female‐biased dispersal in the bullfrog (Rana catesbeiana) based on aspects of their mating system and tested this prediction using data from seven polymorphic DNA microsatellite loci. Allelic (F‐statistics) and genotypic [assignment index, (AIc)] frequencies from nine Ontario populations support our prediction, although significant sex differences in inbreeding and variance of AIc were not detected. The diversity of mating systems found in amphibians represents an important avenue for investigating the relationship between reproductive systems, dispersal and phylogeny.
Genetic structure of Mesoamerican populations of Big‐leaf mahogany (Swietenia macrophylla) inferred from microsatellite analysis
Authors: Novick Rachel Roth , Dick Christopher w. , Lemes Maristerra R. , Navarro Carlos , Caccone Adalgisa , Bermingham Eldredge 
Published: October 2003

AbstractWhile microsatellites have been used to examine genetic structure in local populations of Neotropical trees, genetic studies based on such high‐resolution markers have not been carried out for Mesoamerica as a whole. Here we assess the genetic structure of the Mesoamerican mahogany Swietenia macrophylla King (big‐leaf mahogany), a Neotropical tree species recently listed as endangered in CITES which is commercially extinct through much of its native range. We used seven variable microsatellite loci to assess genetic diversity and population structure in eight naturally established mahogany populations from six Mesoamerican countries. Measures of genetic differentiation (FST and RST) indicated significant differences between most populations. Unrooted dendrograms based on genetic distances between populations provide evidence of strong phylogeographic structure in Mesoamerican mahogany. The two populations on the Pacific coasts of Costa Rica and Panama were genetically distant from all the others, and from one another. The remaining populations formed two clusters, one comprised of the northern populations of Mexico, Belize and Guatemala and the other containing the southern Atlantic populations of Nicaragua and Costa Rica. Significant correlation was found between geographical distance and all pairwise measures of genetic divergence, suggesting the importance of regional biogeography and isolation by distance in Mesoamerican mahogany. The results of this study demonstrate greater phylogeographic structure than has been found across Amazon basin S. macrophylla. Our findings suggest a relatively complex Mesoamerican biogeographic history and lead to the prediction that other Central American trees will show similar patterns of regional differentiation.
Disparate patterns of population genetic structure and population history in two sympatric penaeid shrimp species (Farfantepenaeus aztecusandLitopenaeus setiferus) in the eastern United States
Authors: Mcmillen‐Jackson A. L. , Bert T. M. 
Published: October 2003

AbstractAnalysing the population genetic structures of sympatric species provides opportunities to compare patterns of population genetic structure and phylogeography in order to gain insight into the factors that influence the development of the observed patterns. In this study, we compared the population genetic structures and phylogeographies of brown shrimp (Farfantepenaeus aztecus) and white shrimp (Litopenaeus setiferus), two sympatric penaeid shrimp species that inhabit the waters of the eastern USA, using sequence analysis of the mitochondrial DNA control region. Brown shrimp showed no significant phylogenetic structure or population subdivision, and closely related haplotypes were geographically dispersed. Mismatch analysis indicated that brown shrimp experienced a late‐Pleistocene era sudden population expansion. In contrast, white shrimp had a complex haplotype phylogeny consisting of two distinct lineages and two less well‐defined sublineages, and the haplotypes and lineages were geographically structured. Mismatch analysis for white shrimp also showed evidence of sudden population expansion, albeit for each lineage separately and more recently than in the brown shrimp. These disparate patterns may have developed as a result of species‐specific differences in physiological tolerances and habitat preferences that caused greater fluctuations in white shrimp population sizes and reductions in long‐term effective population size relative to that of the brown shrimp, and thereby increased the susceptibility of the white shrimp populations to stochastic genetic change.
mtDNA perspective of chromosomal diversification and hybridization in Peters’ tent‐making bat (Uroderma bilobatum: Phyllostomidae)
Authors: Hoffmann Federico G. , Owen James G. , Baker Robert J. 
Published: October 2003

AbstractWe compared sequence variation in the complete mitochondrial cytochrome‐bgene with chromosomal and geographical variation for specimens of Peters’ tent‐making bat (Uroderma bilobatum). Three different chromosomal races have been described in this species: a 2n = 42 race from South America east of the Andes, a 2n = 44 from NW Central America and 2n = 38 from the rest of Central America and NW South America. The deepest nodes in the tree were found within the South American race (42 race), which is consistent with a longer history of this race. Average distance among races ranged from 2.5 to 2.9%, with the highest amount of intraracial variation found within the 2n = 42 race (1.7%), intermediate values within the 2n = 38 race (0.9%) and lowest within the 2n = 44 race (0.5%). Variation among chromosomal races accounted for over 55% of molecular variance, whereas variation among populations within races accounted for 6%. The 2n = 38 and 2n = 44 races hybridize in the coastal lowlands of Honduras, near the Gulf of Fonseca. Introgression between these two races is low (two introgressed individuals in 45 examined). Clinal variation across the hybrid zone for the cytochrome‐bofU. bilobatum,is similar to clinal variation reported for chromosomes and isozymes of this species. Mismatch distribution analyses suggests that geographical isolation and karyological changes have interplayed in a synergistic fashion. Fixation of the alternative chromosomal rearrangements in geographical isolation and secondary contact is the most likely mechanism accounting for the hybrid zone between the 2n = 38 and 2n = 44 races. If a molecular clock is assumed, with rates ranging from 2.3 to 5.0% per million years, then isolation between these races occurred within the last million years, implying a relatively recent origin of the extant diversity inUroderma bilobatum. None the less, the three chromosomal races probably represent three different biological species.
Hybridization and introgression betweenCallicarpa japonicaandC. mollis(Verbenaceae) in central Japan, as inferred from nuclear and chloroplast DNA sequences
Authors: Tsukaya Hirokazu , Fukuda Tatsuya , Yokoyama Jun 
Published: October 2003

AbstractCallicarpa × shirasawanais a natural hybrid betweenC.japonicaandC.mollis, and has a morphology that is intermediate between those of the parent species. Characterization of naturalCallicarpapopulations in the Atsumi Peninsula of central Japan, which all three of the above species inhabit sympatrically, revealed hybrids with various morphologies. Molecular analysis revealed a high occurrence of introgression of theC.japonicagenome into that ofC.mollis. Moreover, all individuals examined with morphology similar to that ofC.mollishad genetic traces of hybridization withC.japonica. Molecular analysis of individualC.mollisandC.japonicafrom five other areas of Japan showed that introgression ofC.japonicaintoC.mollisoccurs widely. Molecular data also strongly suggested that the previously recognizedC. × shirasawanaindividuals with intermediate morphology are not F1hybrids betweenC.japonicaandC.mollis, but instead are progeny ofC. × shirasawanabackcrossed withC.japonica. Moreover, it was revealed that individuals with F1‐type genotypes are indistinguishable morphologically from pureC.mollis. The results of the present study point to the need for re‐evaluation of natural populations ofC.mollisandC. × shirasawana.
Cytoplasmic composition in Pinus densata and population establishment of the diploid hybrid pine
Authors: Song Bao‐Hua , Wang Xiao‐Quan , Wang Xiao‐Ru , Ding Kai‐Yu , Hong De‐Yuan 
Published: October 2003

AbstractSequence and restriction site analyses of the paternally inherited chloroplast rbcL gene and maternally inherited mitochondrial nad1 fragments from the same set of populations and individuals were used to investigate cytoplasmic composition and population establishment of Pinus densata, a diploid pine that originated through hybridization between P. tabuliformis and P. yunnanensis. Two variable sites and three chlorotypes (TT, TC and GC) were detected on the rbcL gene of the three pines. P. densata harboured the three chlorotypes, two of which (TT, GC) were characteristic of the parental species, respectively. The third chlorotype (TC) was distributed extensively in seven of the 10 P. densata populations analysed, and might represent a mutation type or have been derived from an extinct parent. The distribution of chlorotypes, together with that of mitotypes, indicated that significant founder effect and backcross happened during the population establishment of the hybrid pine. P. tabuliformis and P. yunnanensis had acted as both mother and father donors, i.e. bi‐directional gene flow existed between the two parental species in the past. Population differentiation of P. densata is high, as detected from the cytoplasmic genomes: GST = 0.533 for cpDNA and GST = 0.905 for mtDNA. The differences in cytoplasmic composition among the hybrid populations suggest that the local populations have undergone different evolutionary histories.
Relationships of Palearctic and Nearctic ‘glacial relict’Myoxocephalussculpins from mitochondrial DNA data
Authors: Kontula Tytti , Väinölä Risto 
Published: October 2003

AbstractThe relationships amongMyoxocephalus quadricorniscomplex fish from Arctic coastal waters and from ‘glacial relict’ populations in Nearctic and Palearctic postglacial lakes were assessed using mtDNA sequence data (1978 bp). A principal phylogeographical split separated the North American continental deepwater sculpin (M. q. thompsonii) from a lineage of the Arctic marine and North European landlocked populations of the fourhorn sculpin (M. q. quadricornis). The North American continental invasion took place several glaciation cycles ago in the Early‐to‐Middle Pleistocene (0.9% sequence divergence); the divergence of the European and Arctic populations was somewhat later (0.5% divergence). The Nearctic‐Palearctic freshwater vicariance inMyoxocephalus, however, appears clearly younger than in similarly distributed ‘glacial relict’ crustacean taxa; the phylogeographical structure is more similar to that in other northern Holarctic freshwater fish complexes.
Lack of mitochondrial genetic structure in hamlets (Hypoplectrusspp.): recent speciation or ongoing hybridization?
Authors: Ramon Marina L. , Lobel Phillip S. , Sorenson Michael D. 
Published: October 2003

AbstractSpecies in the genusHypoplectrus(hamlet fish) have been recognized primarily on the basis of colour morphology, which varies substantially. Limited differentiation in other morphological characters, however, has led to ongoing debate about their taxonomy. Our analysis of mtDNA sequences demonstrates neither reciprocal monophyly nor significant genetic differentiation among hamlet colour morphs. These data are potentially consistent with a model of recent speciation due to sexual selection on colour morphology. The presence within hamlets of two divergent mtDNA clades, however, suggests a longer history during which hybridization and gene flow have prevented the differentiation of hamlet colour morphs, at least in neutral genetic markers.
Co‐existing grass species have distinctive arbuscular mycorrhizal communities
Authors: Vandenkoornhuyse P. , Ridgway K. P. , Watson I. J. , Fitter A. H. , Young J. P. W. 
Published: October 2003

AbstractArbuscular mycorrhizal (AM) fungi are biotrophic symbionts colonizing the majority of land plants, and are of major importance in plant nutrient supply. Their diversity is suggested to be an important determinant of plant community structure, but the influence of host‐plant and environmental factors on AM fungal community in plant roots is poorly documented. Using the terminal restriction fragment length polymorphism (T‐RFLP) strategy, the diversity of AM fungi was assessed in 89 roots of three grass species (Agrostis capillaris,Festuca rubra,Poa pratensis) that co‐occurred in the same plots of a field experiment. The impact of different soil amendments (nitrogen, lime, nitrogen and lime) and insecticide application on AM fungal community was also studied. The level of diversity found in AM fungal communities using the T‐RFLP strategy was consistent with previous studies based on clone libraries. Our results clearly confirm that an AM fungal host‐plant preference exists, even between different grass species. AM communities colonizing A. capillaris were statistically different from the others (P < 0.05). Although grass species evenness changed in amended soils, AM fungal community composition in roots of a given grass species remained stable. Conversely, in plots where insecticide was applied, we found higher AM fungal diversity and, inF. rubraroots, a statistically different AM fungal community.
Social pairing and female mating fidelity predicted by restriction fragment length polymorphism similarity at the major histocompatibility complex in a songbird
Authors: Freeman‐Gallant Corey R. , Meguerdichian Michael , Wheelwright Nathaniel T. , Sollecito Suzanne V. 
Published: October 2003

AbstractFemale birds often copulate outside the pair‐bond to produce broods of mixed paternity, but despite much recent attention the adaptive significance of this behaviour remains elusive. Although several studies support the idea that extra‐pair copulations (EPCs) allow females to obtain ‘good genes’ for their offspring, many others have found no relationship between female mating fidelity and traits likely to reflect male quality. A corollary to the good genes hypothesis proposes that females do use EPCs to increase the quality of young, but it is the interaction between maternal and paternal genomes — and not male qualityper se — that is the target of female choice. We tested this ‘genetic compatibility’ hypothesis in a free‐living population of Savannah sparrows (Passerculus sandwichensis) by determining whether females mated nonrandomly with respect to the major histocompatibility complex (Mhc). During both the 1994 and 1995 breeding seasons, female yearlings (but not older birds) avoided pairing withMhc‐similar males (P < 0.005). TheMhcsimilarity between mates also predicted the occurrence of extra‐pair young in first broods (P < 0.007) and covaried with estimates of genome‐wide levels of similarity derived from multilocus DNA fingerprinting profiles (P = 0.007). The overall genetic similarity between adults tended to predict female mating fidelity, but with less precision than theirMhcsimilarity (P = 0.09). In contrast, females appeared insensitive to the size, weight or age of males, none of which explained variation in female mating fidelity. Taken together, these results are consistent with the hypothesis that females sought complementary genes for their offspring and suggest either that the benefits of heterozygosity (at theMhc) drive female mating patterns or that the avoidance of inbreeding is an ultimate cause of social and genetic mate choice in Savannah sparrows.
Assessing population structure and gene flow in Montana wolverines (Gulo gulo) using assignment‐based approaches
Authors: Cegelski C. C. , Waits L. P. , Anderson N. J. 
Published: October 2003

AbstractIn North America, wolverines once occupied a continuous range from Alaska southward to New Mexico. In the lower 48 states, small remnant populations remain only in the northwestern United States. Among these remnant populations, the Montana population has the highest probability of long‐term persistence given its size and proximity to healthy populations in Canada. In this study, we evaluate population genetic structure and gene flow among Montana wolverines using 10 polymorphic microsatellite loci. Bayesian and frequency‐based assignment tests revealed significant population substructure and provide support for at least three subpopulations in Montana. FST values between subpopulations ranged from 0.08 to 0.10 and provide evidence for male‐biased dispersal. The high degree of population substructure and low levels of gene flow contrast results from wolverine population genetic studies in less fragmented landscapes of Alaska and Canada. This study provides additional support for the hypothesis that large carnivore populations of Montana are becoming increasingly fragmented due to human development and disturbance.