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Multiple Individuals (multiple + individual)
Selected AbstractsDeveloping a Caregiving Tradition in Opposition to One's Past: Lessons from a Longitudinal Study of Teenage MothersPUBLIC HEALTH NURSING, Issue 2 2000D.N.Sc., Lee SmithBattle R.N. Although teenage mothering has been exhaustively studied, the cross-sectional designs and the deficit-finding focus of empirical-rational studies have exaggerated the negative consequences of an early pregnancy and have obscured how teenage mothering is often a rite of passage to adulthood, particularly in the absence of middle-class resources and aspirations. In examining the experiences of young mothers, an 8-year longitudinal study sought to understand how teenage mothers extend and develop family caregiving traditions. The original sample included 16 families and 39 subjects. Multiple individual and family interviews were conducted once the teen's first-born infant reached 8 to 10 months of age, and then 4 and 8 years later. Data from all three study periods were analyzed using the interpretive method. The following analysis provides an in-depth account of how young mothers with an oppressive past strive to become the parents they want to be. In addition, the teen mother's difficulties and struggles of creating a more positive maternal legacy and the role that positive and negative examples of parenting play in fostering or hindering the development of a new caregiving tradition are described. Study findings have implications for how clinical practice and social policy can better assist mothers to become the mothers they want to be. [source] Social status determines sexual phenotype in the bi-directional sex changing bluebanded goby Lythrypnus dalliJOURNAL OF FISH BIOLOGY, Issue 6 2007E. W. Rodgers The behavioural mechanisms and patterns of protandrous sex change in bluebanded gobies Lythrypnus dalli were investigated and compared to the well-described behaviour patterns of protogynous sex change. To do this, unisex groups of males and females were established; behavioural and anatomical changes were recorded over a 42 day period as social status and sexual phenotype were determined. In all cases, social status, rather than the expression of a particular behaviour, accurately predicted final sexual phenotype. Rates of submissive behaviour, but not aggressive behaviour, were predictive of each discrete status class. Multiple individuals changed sex simultaneously if their sexual phenotype and social status were discordant, a novel finding suggesting that once a social hierarchy is established, individuals determined their sexual phenotype, regardless of initial sex, based on a simple operational principle: if subordinate express female, if dominant or not subordinate express male. This work demonstrates that similar mechanisms underlie sex change in both directions in L. dalli and potentially other sex changing species. [source] Differential capacity of T cell priming in naive donors of promiscuous CD4+ T cell epitopes of HCV NS3 and Core proteinsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2007Florence Abstract To understand the inter-individual and virus-independent variability of CD4+ T cell responses to HCV components, we evaluated the effect on these responses of HLA II molecules in uninfected healthy donors. Using HLA II-specific binding assays, we identified, in the Core and NS3 proteins, 21 long fragments and 24 15-mer peptides that bound to four to eight of the most preponderant HLA II molecules. We then evaluated the priming capacity of eight long promiscuous peptides in 12 HLA-unrelated healthy donors. The NS3 1250,1264 peptide primed T cells in all the naive donors, while five others were stimulating in at least half of the individuals. We also report sequences that bind to multiple HLA II molecules but are weakly immunogenic. We therefore conclude that (i) broad HLA II specificity is only a prerequisite for a peptide to be stimulating in multiple individuals, and (ii) promiscuous peptides widely differ in their capacity to prime CD4+ T cells from uninfected healthy donors. We suggest that these priming differences result from inter-individual variations in the peptide-specific T cell repertoire. Interestingly, five of the most immunogenic peptides we identified correspond to frequently targeted T cell epitopes in infected patients. [source] ESTIMATING A GEOGRAPHICALLY EXPLICIT MODEL OF POPULATION DIVERGENCEEVOLUTION, Issue 3 2007L. Lacey Knowles Patterns of genetic variation can provide valuable insights for deciphering the relative roles of different evolutionary processes in species differentiation. However, population-genetic models for studying divergence in geographically structured species are generally lacking. Since these are the biogeographic settings where genetic drift is expected to predominate, not only are population-genetic tests of hypotheses in geographically structured species constrained, but generalizations about the evolutionary processes that promote species divergence may also be potentially biased. Here we estimate a population-divergence model in montane grasshoppers from the sky islands of the Rocky Mountains. Because this region was directly impacted by Pleistocene glaciation, both the displacement into glacial refugia and recolonization of montane habitats may contribute to differentiation. Building on the tradition of using information from the genealogical relationships of alleles to infer the geography of divergence, here the additional consideration of the process of gene-lineage sorting is used to obtain a quantitative estimate of population relationships and historical associations (i.e., a population tree) from the gene trees of five anonymous nuclear loci and one mitochondrial locus in the broadly distributed species Melanoplus oregonensis. Three different approaches are used to estimate a model of population divergence; this comparison allows us to evaluate specific methodological assumptions that influence the estimated history of divergence. A model of population divergence was identified that significantly fits the data better compared to the other approaches, based on per-site likelihood scores of the multiple loci, and that provides clues about how divergence proceeded in M. oregonensis during the dynamic Pleistocene. Unlike the approaches that either considered only the most recent coalescence (i.e., information from a single individual per population) or did not consider the pattern of coalescence in the gene genealogies, the population-divergence model that best fits the data was estimated by considering the pattern of gene lineage coalescence across multiple individuals, as well as loci. These results indicate that sampling of multiple individuals per population is critical to obtaining an accurate estimate of the history of divergence so that the signal of common ancestry can be separated from the confounding influence of gene flow,even though estimates suggest that gene flow is not a predominant factor structuring patterns of genetic variation across these sky island populations. They also suggest that the gene genealogies contain information about population relationships, despite the lack of complete sorting of gene lineages. What emerges from the analyses is a model of population divergence that incorporates both contemporary distributions and historical associations, and shows a latitudinal and regional structuring of populations reminiscent of population displacements into multiple glacial refugia. Because the population-divergence model itself is built upon the specific events shaping the history of M. oregonensis, it provides a framework for estimating additional population-genetic parameters relevant to understanding the processes governing differentiation in geographically structured species and avoids the problems of relying on overly simplified and inaccurate divergence models. The utility of these approaches, as well as the caveats and future improvements, for estimating population relationships and historical associations relevant to genetic analyses of geographically structured species are discussed. [source] Abundance, diversity, and activity of microbial assemblages associated with coral reef fish guts and fecesFEMS MICROBIOLOGY ECOLOGY, Issue 1 2010Steven Smriga Abstract Feces and distal gut contents were collected from three coral reef fish species. Bacteria cell abundances, as determined via epifluorescence microscopy, ranged two orders of magnitude among the fishes. Mass-specific and apparent cell-specific hydrolytic enzyme activities in feces from Chlorurus sordidus were very high, suggesting that endogenous fish enzymes were egested into feces. Denaturing gradient gel electrophoresis profiles of 16S rRNA genes were more similar among multiple individuals of the surgeonfish Acanthurus nigricans than among individuals of the parrotfish C. sordidus or the snapper Lutjanus bohar. Analyses of feces-derived 16S rRNA gene clones revealed that at least five bacterial phyla were present in A. nigricans and that Vibrionaceae comprised 10% of the clones. Meanwhile, C. sordidus contained at least five phyla and L. bohar three, but Vibrionaceae comprised 71% and 76% of the clones, respectively. Many sequences clustered phylogenetically to cultured Vibrio spp. and Photobacterium spp. including Vibrio ponticus and Photobacterium damselae. Other Vibrionaceae -like sequences comprised a distinct phylogenetic group that may represent the presence of ,feces-specific' bacteria. The observed differences among fishes may reflect native gut microbiota and/or bacterial assemblages associated with ingested prey. [source] Molecular systematics of Scaphirhynchinae: an assessment of North American and Central Asian Freshwater Sturgeon SpeciesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2007C. B. Dillman Summary The sturgeon subfamily Scaphirhynchinae contains two genera of obligate freshwater sturgeon: Scaphirhynchus and Pseudoscaphirhynchus, from North America and Central Asia, respectively. Both genera contain morphologically variable species. A novel data set containing multiple individuals representing four diagnosable morphological variants for two species of Pseudoscaphirhynchus, P. hermanni and P. kaufmanni, was generated. These data were used to test taxonomic hypotheses of monophyly for the subfamily Scaphirhynchinae, monophyly of both Scaphirhynchus and Pseudoscaphirhynchus, monophyly of P. hermanni and P. kaufmanni, and monophyly of the recognized morphological variants. Monophyly of the subfamily Scaphirhynchinae is consistently rejected by all phylogenetic reconstruction methodologies with the molecular character set while monophyly of both river sturgeon genera is robustly supported. The molecular data set also rejects hypotheses of monophyly for sampled species of Pseudoscaphirhynchus as well as monophyly for the recognized intraspecific morphological variants. Interestingly both Scaphirhynchus and Pseudoscaphirhynchus demonstrate the same general pattern in reconstructed topologies; a lack of phylogenetic structure in the clade with respect to recognized diversity. Despite rejection of monophyly for the subfamily Scaphirhynchinae with molecular data, reconstructed hypotheses from morphological character sets consistently support monophyly for this subfamily. Disparities among the data sets, as well as reasons for rejection of monophyly for Scaphirhynchinae and species of Scaphirhynchus and Pseudoscaphirhynchus with molecular characters are examined and a decreased rate of molecular evolution is found to be most consistent with the data. [source] Perceived criticism only matters when it comes from those you live withJOURNAL OF CLINICAL PSYCHOLOGY, Issue 12 2007Keith D. RenshawArticle first published online: 30 OCT 200 Perceived criticism (PC) is the amount of criticism that a respondent perceives from another individual, typically a relative with whom the respondent lives. Measured in this way, PC has been shown to predict symptom fluctuation, treatment outcome, and relapse rates across many disorders. Three recent studies failed to replicate these results, but in all three studies, investigators did not require patients to rate people with whom they lived on the measure of PC, which may have changed the overall meaning of the construct. To address this possibility, the current study examined change in depressive symptoms in relation to ratings of PC from multiple individuals who did and did not live with respondents. Only PC from family members or romantic partners who lived with participants predicted change in depressive symptoms. Perceived criticism from friends and PC from individuals ranked as most influential did not. These findings suggest that PC is most meaningful and informative when viewed in its original conceptual form, as a reflection of the family home environment. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 1171,1179, 2007. [source] Use of communal roosts by Andean Condors in northwest Patagonia, ArgentinaJOURNAL OF FIELD ORNITHOLOGY, Issue 2 2008Sergio A. Lambertucci ABSTRACT Andean Condors (Vultur gryphus) are endangered in the northern portion of their South American range, but populations are larger further south. However, throughout their range, little is known about current population sizes and dynamics. Andean Condors use cliffs with shelves as communal roosts and, from 1999 to 2001, we surveyed three of these roosts in northwestern Patagonia, Argentina, to estimate population sizes and trends. The minimum population of Andean Condors in our study area was 196, one of the highest populations recorded for this species. The maximum number of condors observed increased during our 3-yr study. However, there was a strong seasonal pattern in roost use and use also varied among roosts, possibly due to differences in their environmental characteristics, size, and room available for roosting, as well as proximity to nest sites and stage of the breeding season. In 1999 and 2000, more adults were observed than juveniles, but proportions were similar in 2001. Because we observed differential use of roosts among age classes, spatial segregation seems probable. We conclude that intensive censuses of communal roosts can provide useful information about the size, status, and dynamics of local populations. However, the large aggregations we observed may represent a potential risk for the conservation of the species because a single threat could affect multiple individuals. We suggest that a suitable conservation strategy for condors must involve the design and protection of a network of communal roosts. SINOPSIS El Cóndor Andino (Vultur gryphus) es una especie en peligro de extinción en el norte de su distribución Sudamericana, pero sus poblaciones son más abundantes hacia el sur. Sin embargo, poco se conoce sobre los tamaños de las poblaciones y sus dinámicas a lo largo de su distribución. El cóndor usa acantilados con repisas para descansar y pernoctar comunalmente a lo largo del año. Entre 1999-2001 censamos tres de estos dormideros en el noroeste de la Patagonia Argentina para estimar el tamaño poblacional y los patrones de uso. El tamaño poblacional mínimo de la especie en nuestra área de estudio fue de 196 individuos, el cual es de los más grandes registrados para el Cóndor Andino. Aunque el número máximo de cóndores aumentó durante los tres años de estudio, hubo un fuerte patrón estacional del uso de los dormideros. También encontramos variación en el uso entre dormideros posiblemente debida a las diferencias en sus características ambientales, tamaño, espacio disponible para perchar, proximidad a sitios de nidificación y la fase del período reproductivo. En 1999 y 2000 observamos más adultos que juveniles, pero las proporciones fueron similares en 2001. Observamos diferencias en el uso de cada dormidero entre estadios etarios, por lo cual es factible la segregación espacial por edades. Concluimos que los censos intensivos de dormideros comunales pueden proveer información útil sobre el tamaño, estatus y las dinámicas de las poblaciones locales. Sin embargo, grandes agregaciones como las observadas podrían representar un riesgo para la conservación de esta especie, ya que una sola una amenaza podría afectar a muchos individuos. Sugerimos que una estrategia de conservación adecuada para el Cóndor Andino debería involucrar el diseño y protección de una red de dormideros comunales. [source] Phylogenetics and biogeography of eastern Asian,North American disjunct genus Pachysandra (Buxaceae) inferred from nucleotide sequencesJOURNAL OF SYSTEMATICS EVOLUTION, Issue 3 2009Zhihua JIAO Abstract Pachysandra is an eastern Asian,North American disjunct genus with three species, two in eastern Asia (Pachysandra axillaris and Pachysandra terminalis) and one in eastern North America (Pachysandra procumbens). Although morphological and cytological studies suggest a close affinity of P. procumbens with P. axillaris, molecular data from nuclear and chloroplast DNA regions have provided conflicting signals. In this study, we tested previous phylogenetic hypotheses using sequences of nuclear ribosomal DNA internal transcribed spacers and chloroplast ndhF gene from multiple individuals of each of the three species. We also estimated the time of divergence between eastern Asia and eastern North America. Our results support the morphological and cytological conclusion that P. procumbens is more closely related to P. axillaris than to P. terminalis. The estimated time of divergence of P. axillaris and P. procumbens was 14.6±5.5 mya, consistent with estimates from many other eastern Asian,North American disjunct genera. The migration of Pachysandra populations from eastern Asia to North America might have occurred by way of the North Atlantic land bridge. [source] Neuroimaging of Language: Why Hasn't a Clearer Picture Emerged?LINGUISTICS & LANGUAGE COMPASS (ELECTRONIC), Issue 4 2009Evelina Fedorenko Two broad questions have driven dozens of studies on the neural basis of language published in the last several decades: (i) Are distinct cortical regions engaged in different aspects of language? (ii) Are regions engaged in language processing specific to the domain of language? Neuroimaging has not yet provided clear answers to either question. In this paper, we discuss one factor that is a likely contributor to the unclear state of affairs in the neurocognition of language, and that, in our opinion, has not received sufficient attention in the recent literature. In particular, fMRI studies of language have relied, almost exclusively, on group analyses, in which data from multiple individuals are co-registered to and analyzed in a common space. We argue that this approach can obscure functional specificity because of the anatomical variability across individual brains, and we advocate the use of an alternative approach , the functional localization approach , that circumvents this problem. [source] Comparative genomics and the study of evolution by natural selectionMOLECULAR ECOLOGY, Issue 21 2008HANS ELLEGREN Abstract Genomics profoundly affects most areas of biology, including ecology and evolutionary biology. By examining genome sequences from multiple species, comparative genomics offers new insight into genome evolution and the way natural selection moulds DNA sequence evolution. Functional divergence, as manifested in the accumulation of nonsynonymous substitutions in protein-coding genes, differs among lineages in a manner seemingly related to population size. For example, the ratio of nonsynonymous to synonymous substitution (dN/dS) is higher in apes than in rodents, compatible with Ohta's nearly neutral theory of molecular evolution, which suggests that the fixation of slightly deleterious mutations contributes to protein evolution at an extent negatively correlated with effective population size. While this supports the idea that functional evolution is not necessarily adaptive, comparative genomics is uncovering a role for positive Darwinian selection in 10,40% of all genes in different lineages, estimates that are likely to increase when the addition of more genomes gives increased power. Again, population size seems to matter also in this context, with a higher proportion of fixed amino acid changes representing advantageous mutations in large populations. Genes that are particularly prone to be driven by positive selection include those involved with reproduction, immune response, sensory perception and apoptosis. Genetic innovations are also frequently obtained by the gain or loss of complete gene sequences. Moreover, it is increasingly realized, from comparative genomics, that purifying selection conserves much more than just the protein-coding part of the genome, and this points at an important role for regulatory elements in trait evolution. Finally, genome sequencing using outbred or multiple individuals has provided a wealth of polymorphism data that gives information on population history, demography and marker evolution. [source] Impact and Quantification of the Sources of Error in DNA Pooling DesignsANNALS OF HUMAN GENETICS, Issue 1 2009A. Jawaid Summary The analysis of genome wide variation offers the possibility of unravelling the genes involved in the pathogenesis of disease. Genome wide association studies are also particularly useful for identifying and validating targets for therapeutic intervention as well as for detecting markers for drug efficacy and side effects. The cost of such large-scale genetic association studies may be reduced substantially by the analysis of pooled DNA from multiple individuals. However, experimental errors inherent in pooling studies lead to a potential increase in the false positive rate and a loss in power compared to individual genotyping. Here we quantify various sources of experimental error using empirical data from typical pooling experiments and corresponding individual genotyping counts using two statistical methods. We provide analytical formulas for calculating these different errors in the absence of complete information, such as replicate pool formation, and for adjusting for the errors in the statistical analysis. We demonstrate that DNA pooling has the potential of estimating allele frequencies accurately, and adjusting the pooled allele frequency estimates for differential allelic amplification considerably improves accuracy. Estimates of the components of error show that differential allelic amplification is the most important contributor to the error variance in absolute allele frequency estimation, followed by allele frequency measurement and pool formation errors. Our results emphasise the importance of minimising experimental errors and obtaining correct error estimates in genetic association studies. [source] Family studies in chronic lymphocytic leukaemia and other lymphoproliferative tumoursBRITISH JOURNAL OF HAEMATOLOGY, Issue 5 2007Lynn R. Goldin Summary Families with multiple individuals affected with chronic lymphocytic leukaemia (CLL) and other related B-cell tumours have been described in the literature. Familial CLL does not appear to differ from sporadic CLL in terms of prognostic markers and clinical outcome. Large, population-based case,control and cohort studies have also shown significant familial aggregation of CLL and related conditions, including non-Hodgkin and Hodgkin lymphoma. Monoclonal B-cell lymphocytosis also aggregates in CLL families. However, the clinical implication of familial aggregation is minimal given the overall rarity of CLL. Linkage studies have been conducted in high-risk CLL families to screen the whole genome for loci that contribute to susceptibility but no gene mutations have yet been identified by this method. Association studies of candidate genes have implicated immune function and other genes but more studies are needed to verify these findings. The ability to conduct large scale genomic studies will play an important role in detecting susceptibility genes for CLL over the next few years and thereby help to delineate aetiological pathways. [source] | ||||||||||||||||