Assessing the Landscape of U.S. Postdoctoral Salaries, bioRxiv, 2017-12-04

AbstractPurposePostdocs make up a significant portion of the biomedical workforce. However, data about the postdoctoral position are generally scarce, including salary data. The purpose of this study was to request, obtain and interpret actual salaries, and the associated job titles, for postdocs at U.S. public institutions.MethodologyFreedom of Information Act Requests were submitted to U.S. public institutions estimated to have at least 300 postdocs according to the National Science Foundation’s Survey of Graduate Students and Postdocs. Salaries and job titles of postdoctoral employees as of December 1st, 2016 were requested.FindingsSalaries and job titles for over 13,000 postdocs at 52 public U.S. institutions and 1 private institution around the date of December 1st, 2016 were received, and individual postdoc names were also received for approximately 7,000 postdocs. This study shows evidence of gender-related salary discrepancies, a significant influence of job title description on postdoc salary, and a complex relationship between salaries and the level of institutional NIH funding.ValueThese results provide insights into the ability of institutions to collate actual payroll-type data related to their postdocs, highlighting difficulties faced in tracking, and reporting data on this population. Ultimately, these types of efforts, aimed at increasing transparency, may lead to improved tracking and support for postdocs at all U.S. institutions.

biorxiv scientific-communication-and-education 100-200-users 2017

Model-based detection and analysis of introgressed Neanderthal ancestry in modern humans, bioRxiv, 2017-12-02

AbstractGenetic evidence has revealed that the ancestors of modern human populations outside of Africa and their hominin sister groups, notably the Neanderthals, exchanged genetic material in the past. The distribution of these introgressed sequence-tracts along modern-day human genomes provides insight into the ancient structure and migration patterns of these archaic populations. Furthermore, it facilitates studying the selective processes that lead to the accumulation or depletion of introgressed genetic variation. Recent studies have developed methods to localize these introgressed regions, reporting long regions that are depleted of Neanderthal introgression and enriched in genes, suggesting negative selection against the Neanderthal variants. On the other hand, enriched Neanderthal ancestry in hair- and skin-related genes suggests that some introgressed variants facilitated adaptation to new environments. Here, we present a model-based method called diCal-admix and apply it to detect tracts of Neanderthal introgression in modern humans. We demonstrate its efficiency and accuracy through extensive simulations. We use our method to detect introgressed regions in modern human individuals from the 1000 Genomes Project, using a high coverage genome from a Neanderthal individual from the Altai mountains as reference. Our introgression detection results and findings concerning their functional implications are largely concordant with previous studies, and are consistent with weak selection against Neanderthal ancestry. We find some evidence that selection against Neanderthal ancestry was due to higher genetic load in Neanderthals, resulting from small effective population size, rather than Dobzhansky-Müller incompatibilities. Finally, we investigate the role of the X-chromosome in the divergence between Neanderthals and modern humans.

biorxiv evolutionary-biology 0-100-users 2017

Partially redundant actin genes in Chlamydomonas control flagellum-directed traffic and transition zone organization, bioRxiv, 2017-12-01

ABSTRACTFlagella of the unicellular green alga Chlamydomonas reinhardtii are nearly identical to cilia of mammalian cells and provide an excellent model to study ciliogenesis. These biflagellated cells have two actin genes one encoding a conventional actin (IDA5) and the other encoding a divergent novel actin-like protein (NAP1). Previously, we described a role for actin in the regulation of flagella-building intraflagellar transport machinery. Here, we probe how actin redundancy contributes to this process using a nap1 mutant Chlamydomonas strain. Disruption of a single actin allows normal or slower incorporation but complete flagellar assembly. However, when we disrupt both actins using Latrunculin B (LatB) treatment on the nap1 mutant background, we find flagellar growth from newly synthesized limiting flagellar proteins is actin-dependent. Upon total actin disruption during flagellar assembly, transmission electron microscopy identified an accumulation of Golgi-adjacent vesicles, suggesting impaired vesicular trafficking may be the mechanism by which actin supports flagellar growth from new flagellar proteins. We also find there is a mislocalization of a key transition zone gating and ciliopathy protein, NPHP-4. Extended (2 hour) treatment with LatB, a condition under which NAP1 is upregulated, restores NPHP-4 localization. This suggests NAP1 can perform the functions of conventional actin at the transition zone. Our experiments demonstrate that each stage of flagellar biogenesis requires redundant actin function to varying degrees, with an absolute requirement for these actins in transport of Golgi-adjacent vesicles and flagellar incorporation of newly synthesized proteins.

biorxiv cell-biology 0-100-users 2017

 

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