Different processes lead to similar patterns: a test of codivergence and the role of sea level and climate changes in shaping a southern temperate freshwater assemblage

<p>Abstract</p> <p>Background</p> <p>Understanding how freshwater assemblages have been formed and maintained is a fundamental goal in evolutionary and ecological disciplines. Here we use a historical approach to test the hypothesis of codivergence in three clades of the Chilean freshwater species assemblage. Molecular studies of freshwater crabs (<it>Aegla</it>: Aeglidae: Anomura) and catfish (<it>Trichomycterus arealatus</it>: Trichomycteridae: Teleostei) exhibited similar levels of genetic divergences of mitochondrial lineages between species of crabs and phylogroups of the catfish, suggesting a shared evolutionary history among the three clades in this species assemblage.</p> <p>Results</p> <p>A phylogeny was constructed for <it>Trichomycterus areolatus </it>under the following best-fit molecular models of evolution GTR + I + R, HKY + I, and HKY for cytochrome <it>b</it>, growth hormone, and rag 1 respectively. A GTR + I + R model provided the best fit for both 28S and mitochondrial loci and was used to construct both <it>Aegla </it>phylogenies. Three different diversification models were observed and the three groups arose during different time periods, from 2.25 to 5.05 million years ago (Ma). Cladogenesis within <it>Trichomycterus areolatus </it>was initiated roughly 2.25 Ma (Late Pliocene - Early Pleistocene) some 1.7 - 2.8 million years after the basal divergences observed in both <it>Aegla </it>clades. These results reject the hypothesis of codivergence.</p> <p>Conclusions</p> <p>The similar genetic distances between terminal sister-lineages observed in these select taxa from the freshwater Chilean species assemblage were formed by different processes occurring over the last ~5.0 Ma. Dramatic changes in historic sea levels documented in the region appear to have independently shaped the evolutionary history of each group. Our study illustrates the important role that history plays in shaping a species assemblage and argues against assuming similar patterns equal a shared evolutionary history.</p

An Analysis of Private School Closings

We add to the small literature on private school supply by exploring exits of K-12 private schools. We find that the closure of private schools is not an infrequent event, and use national survey data from the National Center for Education Statistics to study closures of private schools. We assume that the probability of an exit is a function of excess supply of private schools over the demand, as well as the school's characteristics such as age, size, and religious affiliation. Our empirical results generally support the implications of the model. Working Paper 07-0

The brazilian Amaryllidaceae as a source of acetylcholinesterase inhibitory alkaloids

Nine Brazilian Amaryllidaceae species were studied for their alkaloid composition and acetylcholinesterase (AChE) inhibitory activity via GC-MS and a modified Ellman assay, respectively. A total of thirty-six alkaloids were identified in these plants, of which Hippeastrum papilio and H. glau-cescens exhibited the highest galanthamine content and the best IC50 values against AChE. Furthermore, Hippeastrum vittatum and Rhodophiala bifida also showed notable AChE inhibitory effects. X-ray crys-tallographic data for four galanthamine-type com-pounds revealed significant differences in the orientation of theN-methyl group, which are shown to be related to AChE inhibition

Self-esteem and delinquency revisited

A recent investigation by Rosenberg and Rosenberg used longitudinal data from the Youth in Transition study to explore the causal relationships between delinquency and self-esteem. The present study is based on the same sample of young men in high school and extends Rosenberg and Rosenberg's analysis, first by using the same cross-lagged correlation methods applied over a longer time period, and then by employing a “causal modeling” approach using the LISREL computer program. Each of the analyses was carried out using the total sample as well as two subsamples, the highest and lowest quartiles in initial self-esteem. The causal modeling analyses attempted (a) to take careful account of the actual periods referenced by the measures of delinquency and self-esteem, (b) to control socioeconomic status and ability, and (c) to extend the model to demonstrate ways in which participation in teenage social life and current educational attainment might also influence and be influenced by self-esteem. The analyses suggest that self-esteem plays little part in influencing the teenage behaviors and orientations that follow in time. Consistent with Kaplan's prediction, among young men who enter high school with low self-esteem, the effects of delinquent behavior tend primarily to be self-enhancing.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45258/1/10964_2005_Article_BF02087937.pd

Whole genome identification of Mycobacterium tuberculosis vaccine candidates by comprehensive data mining and bioinformatic analyses

<p>Abstract</p> <p>Background</p> <p><it>Mycobacterium tuberculosis</it>, the causative agent of tuberculosis (TB), infects ~8 million annually culminating in ~2 million deaths. Moreover, about one third of the population is latently infected, 10% of which develop disease during lifetime. Current approved prophylactic TB vaccines (BCG and derivatives thereof) are of variable efficiency in adult protection against pulmonary TB (0%–80%), and directed essentially against early phase infection.</p> <p>Methods</p> <p>A genome-scale dataset was constructed by analyzing published data of: (1) global gene expression studies under conditions which simulate intra-macrophage stress, dormancy, persistence and/or reactivation; (2) cellular and humoral immunity, and vaccine potential. This information was compiled along with revised annotation/bioinformatic characterization of selected gene products and <it>in silico </it>mapping of T-cell epitopes. Protocols for scoring, ranking and prioritization of the antigens were developed and applied.</p> <p>Results</p> <p>Cross-matching of literature and <it>in silico</it>-derived data, in conjunction with the prioritization scheme and biological rationale, allowed for selection of 189 putative vaccine candidates from the entire genome. Within the 189 set, the relative distribution of antigens in 3 functional categories differs significantly from their distribution in the whole genome, with reduction in the Conserved hypothetical category (due to improved annotation) and enrichment in Lipid and in Virulence categories. Other prominent representatives in the 189 set are the PE/PPE proteins; iron sequestration, nitroreductases and proteases, all within the Intermediary metabolism and respiration category; ESX secretion systems, resuscitation promoting factors and lipoproteins, all within the Cell wall category. Application of a ranking scheme based on qualitative and quantitative scores, resulted in a list of 45 best-scoring antigens, of which: 74% belong to the dormancy/reactivation/resuscitation classes; 30% belong to the Cell wall category; 13% are classical vaccine candidates; 9% are categorized Conserved hypotheticals, all potentially very potent T-cell antigens.</p> <p>Conclusion</p> <p>The comprehensive literature and <it>in silico</it>-based analyses allowed for the selection of a repertoire of 189 vaccine candidates, out of the whole-genome 3989 ORF products. This repertoire, which was ranked to generate a list of 45 top-hits antigens, is a platform for selection of genes covering all stages of <it>M. tuberculosis </it>infection, to be incorporated in rBCG or subunit-based vaccines.</p