1,014 research outputs found
A Comparison of the Population Genetic Structure and Diversity between a Common (\u3cem\u3eChrysemys p. picta\u3c/em\u3e) and an Endangered (\u3cem\u3eClemmys guttata\u3c/em\u3e) Freshwater Turtle
The northeastern United States has experienced dramatic alteration to its landscape since the time of European settlement. This alteration has had major impacts on the distribution and abundance of wildlife populations, but the legacy of this landscape change remains largely unexplored for most species of freshwater turtles. We used microsatellite markers to characterize and compare the population genetic structure and diversity between an abundant generalist, the eastern painted turtle (Chrysemys p. picta), and the rare, more specialized, spotted turtle (Clemmys guttata) in Rhode Island, USA. We predicted that because spotted turtles have disproportionately experienced the detrimental effects of habitat loss and fragmentation associated with landscape change, that these effects would manifest in the form of higher inbreeding, less diversity, and greater population genetic structure compared to eastern painted turtles. As expected, eastern painted turtles exhibited little population genetic structure, showed no evidence of inbreeding, and little differentiation among sampling sites. For spotted turtles, however, results were consistent with certain predictions and inconsistent with others. We found evidence of modest inbreeding, as well as tentative evidence of recent population declines. However, genetic diversity and differentiation among sites were comparable between species. As our results do not suggest any major signals of genetic degradation in spotted turtles, the southern region of Rhode Island may serve as a regional conservation reserve network, where the maintenance of population viability and connectivity should be prioritized
Pregnane steroidogenesis is altered by HIV-1 Tat and morphine: Physiological allopregnanolone is protective against neurotoxic and psychomotor effects
Pregnane steroids, particularly allopregnanolone (AlloP), are neuroprotective in response to central insult. While unexplored in vivo, AlloP may confer protection against the neurological dysfunction associated with human immunodeficiency virus type 1 (HIV-1). The HIV-1 regulatory protein, trans-activator of transcription (Tat), is neurotoxic and its expression in mice increases anxiety-like behavior; an effect that can be ameliorated by progesterone, but not when 5α-reduction is blocked. Given that Tat\u27s neurotoxic effects involve mitochondrial dysfunction and can be worsened with opioid exposure, we hypothesized that Tat and/or combined morphine would perturb steroidogenesis in mice, promoting neuronal death, and that exogenous AlloP would rescue these effects. Like other models of neural injury, conditionally inducing HIV-1 Tat in transgenic mice significantly increased the central synthesis of pregnenolone and progesterone\u27s 5α-reduced metabolites, including AlloP, while decreasing central deoxycorticosterone (independent of changes in plasma). Morphine significantly increased brain and plasma concentrations of several steroids (including progesterone, deoxycorticosterone, corticosterone, and their metabolites) likely via activation of the hypothalamic-pituitary-adrenal stress axis. Tat, but not morphine, caused glucocorticoid resistance in primary splenocytes. In neurons, Tat depolarized mitochondrial membrane potential and increased cell death. Physiological concentrations of AlloP (0.1, 1, or 10 nM) reversed these effects. High-concentration AlloP (100 nM) was neurotoxic in combination with morphine. Tat induction in transgenic mice potentiated the psychomotor effects of acute morphine, while exogenous AlloP (1.0 mg/kg, but not 0.5 mg/kg) was ameliorative. Data demonstrate that steroidogenesis is altered by HIV-1 Tat or morphine and that physiological AlloP attenuates resulting neurotoxic and psychomotor effects
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Alternative Splicing in the Obligate Biotrophic Oomycete Pathogen Pseudoperonospora cubensis
Pseudoperonospora cubensis is an obligate pathogen and
causative agent of cucurbit downy mildew. To help advance
our understanding of the pathogenicity of P. cubensis, we
used RNA-Seq to improve the quality of its reference
genome sequence. We also characterized the RNA-Seq
dataset to inventory transcript isoforms and infer alternative
splicing during different stages of its development. Almost
half of the original gene annotations were improved
and nearly 4,000 previously unannotated genes were identified.
We also demonstrated that approximately 24% of
the expressed genome and nearly 55% of the intron-containing
genes from P. cubensis had evidence for alternative
splicing. Our analyses revealed that intron retention is the
predominant alternative splicing type in P. cubensis, with
alternative 5′- and alternative 3′-splice sites occurring at
lower frequencies. Representatives of the newly identified
genes and predicted alternatively spliced transcripts were
experimentally validated. The results presented herein
highlight the utility of RNA-Seq for improving draft genome
annotations and, through this approach, we demonstrate
that alternative splicing occurs more frequently than
previously predicted. In total, the current study provides
evidence that alternative splicing plays a key role in transcriptome
regulation and proteome diversification in plantpathogenic
oomycetes
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