PRESENCE AND PREVALENCE OF BD (BATRACHOCHYTRIUM DENDROBATIDIS) IN CENTRAL PENNSYLVANIAN WOODLAND VERNAL POOLS

Batrachochytrium dendrobatidis (Bd), a virulent chytrid fungus responsible for dramatic amphibian declines, has been detected in the northwestern and southeastern regions of Pennsylvania. However, little environmental Bd testing has been performed in central Pennsylvania, particularly in the unique and speciose habitats of woodland vernal pools. Our study included sampling in four vernal pools over a period of three months during amphibian breeding periods. Skin swabs were taken from three caudate and two anuran species, during the course of late winter and spring migrations (n = 143). Low Bd zoospore equivalent loads were detected in only a few individuals, in three of the five species but in all four vernal pools sampled. No significant trends were seen between zoospore loads and ambient temperature or migration timing across the species sampled

Recent and Rapid Radiation of the Highly Endangered Harlequin Frogs (Atelopus) into Central America Inferred from Mitochondrial DNA Sequences

Populations of amphibians are experiencing severe declines worldwide. One group with the most catastrophic declines is the Neotropical genus Atelopus (Anura: Bufonidae). Many species of Atelopus have not been seen for decades and all eight Central American species are considered “Critically Endangered”, three of them very likely extinct. Nonetheless, the taxonomy, phylogeny, and biogeographic history of Central American Atelopus are still poorly known. In this study, the phylogenetic relationships among seven of the eight described species in Central America were inferred based on mitochondrial DNA sequences from 103 individuals, including decades-old museum samples and two likely extinct species, plus ten South American species. Among Central American samples, we discovered two candidate species that should be incorporated into conservation programs. Phylogenetic inference revealed a ladderized topology, placing species geographically furthest from South America more nested in the tree. Model-based ancestral area estimation supported either one or two colonization events from South America. Relaxed-clock analysis of divergence times indicated that Atelopus colonized Central America prior to 4 million years ago (Ma), supporting a slightly older than traditional date for the closure of the Isthmus. This study highlights the invaluable role of museum collections in documenting past biodiversity, and these results could guide future conservation efforts

Loss of Hsp70 Exacerbates Pathogenesis But Not Levels of Fibrillar Aggregates in a Mouse Model of Huntington's Disease

Endogenous protein quality control machinery has long been suspected of influencing the onset and progression of neurodegenerative diseases characterized by accumulation of misfolded proteins. Huntington's disease (HD) is a fatal neurodegenerative disorder caused by an expansion of a polyglutamine (polyQ) tract in the protein huntingtin (htt), which leads to its aggregation and accumulation in inclusion bodies. Here, we demonstrate in a mouse model of HD that deletion of the molecular chaperones Hsp70.1 and Hsp70.3 significantly exacerbated numerous physical, behavioral and neuropathological outcome measures, including survival, body weight, tremor, limb clasping and open field activities. Deletion of Hsp70.1 and Hsp70.3 significantly increased the size of inclusion bodies formed by mutant htt exon 1, but surprisingly did not affect the levels of fibrillar aggregates. Moreover, the lack of Hsp70s significantly decreased levels of the calcium regulated protein c-Fos, a marker for neuronal activity. In contrast, deletion of Hsp70s did not accelerate disease in a mouse model of infectious prion-mediated neurodegeneration, ruling out the possibility that the Hsp70.1/70.3 mice are nonspecifically sensitized to all protein misfolding disorders. Thus, endogenous Hsp70s are a critical component of the cellular defense against the toxic effects of misfolded htt protein in neurons, but buffer toxicity by mechanisms independent of the deposition of fibrillar aggregates

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements