2,892 research outputs found

    Phylogeny, diversification, and biogeography of a hemiclonal hybrid system of native Australian freshwater fishes (Gobiiformes:Gobioidei: Eleotridae: Hypseleotris)

    Get PDF
    BACKGROUND: Carp gudgeons (genus Hypseleotris) are a prominent part of the Australian freshwater fish fauna, with species distributed around the western, northern, and eastern reaches of the continent. We infer a calibrated phylogeny of the genus based on nuclear ultraconserved element (UCE) sequences and using Bayesian estimation of divergence times, and use this phylogeny to investigate geographic patterns of diversification with GeoSSE. The southeastern species have hybridized to form hemiclonal lineages, and we also resolve relationships of hemiclones and compare their phylogenetic placement in the UCE phylogeny with a hypothesis based on complete mitochondrial genomes. We then use phased SNPs extracted from the UCE sequences for population structure analysis among the southeastern species and hemiclones. RESULTS: Hypseleotris cyprinoides, a widespread euryhaline species known from throughout the Indo-Pacific, is resolved outside the remainder of the species. Two Australian radiations comprise the bulk of Hypseleotris, one primarily in the northwestern coastal rivers and a second inhabiting the southeastern region including the Murray–Darling, Bulloo-Bancannia and Lake Eyre basins, plus coastal rivers east of the Great Dividing Range. Our phylogenetic results reveal cytonuclear discordance between the UCE and mitochondrial hypotheses, place hemiclone hybrids among their parental taxa, and indicate that the genus Kimberleyeleotris is nested within the northwestern Hypseleotris radiation along with three undescribed species. We infer a crown age for Hypseleotris of 17.3 Ma, date the radiation of Australian species at roughly 10.1 Ma, and recover the crown ages of the northwestern (excluding H. compressa) and southeastern radiations at 5.9 and 7.2 Ma, respectively. Range-dependent diversification analyses using GeoSSE indicate that speciation and extinction rates have been steady between the northwestern and southeastern Australian radiations and between smaller radiations of species in the Kimberley region and the Arnhem Plateau. Analysis of phased SNPs confirms inheritance patterns and reveals high levels of heterozygosity among the hemiclones. CONCLUSIONS: The northwestern species have restricted ranges and likely speciated in allopatry, while the southeastern species are known from much larger areas, consistent with peripatric speciation or allopatric speciation followed by secondary contact. Species in the northwestern Kimberley region differ in shape from those in the southeast, with the Kimberley species notably more elongate and slender than the stocky southeastern species, likely due to the different topographies and flow regimes of the rivers they inhabit

    Optimizing viable leukocyte sampling from the female genital tract for clinical trials: an international multi-site study

    Get PDF
    BACKGROUND: Functional analysis of mononuclear leukocytes in the female genital mucosa is essential for understanding the immunologic effects of HIV vaccines and microbicides at the site of HIV exposure. However, the best female genital tract sampling technique is unclear. Methods and FINDINGS: We enrolled women from four sites in Africa and the US to compare three genital leukocyte sampling methods: cervicovaginal lavages (CVL), endocervical cytobrushes, and ectocervical biopsies. Absolute yields of mononuclear leukocyte subpopulations were determined by flow cytometric bead-based cell counting. Of the non-invasive sampling types, two combined sequential cytobrushes yielded significantly more viable mononuclear leukocytes than a CVL (p<0.0001). In a subsequent comparison, two cytobrushes yielded as many leukocytes (∼10,000) as one biopsy, with macrophages/monocytes being more prominent in cytobrushes and T lymphocytes in biopsies. Sample yields were consistent between sites. In a subgroup analysis, we observed significant reproducibility between replicate same-day biopsies (r = 0.89, p = 0.0123). Visible red blood cells in cytobrushes increased leukocyte yields more than three-fold (p = 0.0078), but did not change their subpopulation profile, indicating that these leukocytes were still largely derived from the mucosa and not peripheral blood. We also confirmed that many CD4 + T cells in the female genital tract express the α4β7 integrin, an HIV envelope-binding mucosal homing receptor. CONCLUSIONS: CVL sampling recovered the lowest number of viable mononuclear leukocytes. Two cervical cytobrushes yielded comparable total numbers of viable leukocytes to one biopsy, but cytobrushes and biopsies were biased toward macrophages and T lymphocytes, respectively. Our study also established the feasibility of obtaining consistent flow cytometric analyses of isolated genital cells from four study sites in the US and Africa. These data represent an important step towards implementing mucosal cell sampling in international clinical trials of HIV prevention

    Design and analysis of low boom concepts at Langley Research Center

    Get PDF
    The objective of the sonic boom research in the current High Speed Research Program is to ultimately make possible overland supersonic flight by a high speed civil transport. To accomplish this objective, it is felt that results in four areas must demonstrate that such a vehicle would be acceptable by the general public, by the airframers, and by the airlines. It should be demonstrated: (1) that some waveform shape has the possibility of being acceptable to the general public; (2) that the atmosphere would not totally destroy such a waveform during propagation; (3) that a viable airplane could be built which produces such a waveform; and (4) that any performance penalty suffered by a low boom aircraft would be counteracted by the economic benefit of overland supersonic flight. The work being done at LaRC is in support of the third element listed above--the area of configuration design. The initial part of the paper will give a review of the theory being used for configuration designs and discuss two theory validation models which were built and tested within the past two years. Discussion of the wind tunnel and theoretical results (linear theory and higher order methods) and their implications for future designs will be included

    Sexual Health Teaching in the Family Medicine Clerkship: Results of a CERA Survey

    Get PDF
    Introduction: With growing efforts to provide comprehensive and inclusive sexual health care, family medicine clerkships are well positioned to educate learners about a spectrum of related topics. This study investigated the current state of sexual health instruction in family medicine clerkships, including specific factors impacting its delivery. Methods: Questions about sexual health curricula were created and included as part of the 2020 Council of Academic Family Medicine's Educational Research Alliance survey of family medicine clerkship directors. The survey was distributed via email to 163 recipients between June 1, 2020 and June 25, 2020. Results: One hundred five (64.42%) of 163 clerkship directors responded to the survey. Our results revealed that during family medicine clerkships, family planning, contraception, and pregnancy options counseling are covered significantly more often than topics related to sexual dysfunction and satisfaction and LGBTQ+ health. Most clerkship directors (91.5%) reported less than 5 hours of sexual health training in their curriculum. Those with more dedicated sexual health curricular hours were more likely to include simulation. Lack of time (41.7%) was the most frequently reported barrier to incorporating sexual health content into the clerkship. Conclusions: Coverage of sexual health topics during the family medicine clerkship is limited in scope and delivery. To support curricular development and integration, future studies should more thoroughly examine the factors influencing the inclusion of sexual health content in family medicine clerkships as well as the development of assessment methods to determine competency

    Active site inhibitors protect protein kinase C from dephosphorylation and stabilize its mature

    Get PDF
    Conformational changes acutely control protein kinase C (PKC). We have previously shown that the autoinhibitory pseudosubstrate must be removed from the active site in order for 1) PKC to be phosphorylated by its upstream kinase phosphoinositide-dependent kinase 1 (PDK-1), 2) the mature enzyme to bind and phosphorylate substrates, and 3) the mature enzyme to be dephosphorylated by phosphatases. Here we show an additional level of conformational control; binding of active site inhibitors locks PKC in a conformation in which the priming phosphorylation sites are resistant to dephosphorylation. Using homogeneously pure PKC, we show that the active site inhibitor Gö 6983 prevents the dephosphorylation by pure protein phosphatase 1 (PP1) or the hydrophobic motif phosphatase, pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP). Consistent with results using pure proteins, treatment of cells with the competitive inhibitors Gö 6983 or bisindolylmaleimide I, but not the uncompetitive inhibitor bisindolylmaleimide IV, prevents the dephosphorylation and down-regulation of PKC induced by phorbol esters. Pulse-chase analyses reveal that active site inhibitors do not affect the net rate of priming phosphorylations of PKC; rather, they inhibit the dephosphorylation triggered by phorbol esters. These data provide a molecular explanation for the recent studies showing that active site inhibitors stabilize the phosphorylation state of protein kinases B/Akt and C. PKC isozymes comprise a family of multidomain proteins that are under exquisite conformational control. Two major mechanisms control the conformation of PKC family members: phosphorylation and second messenger-dependent membrane binding (1, 2). First, newly synthesized enzymes undergo a series of ordered phosphorylations that lock the enzyme into a stable, catalytically competent, and autoinhibited species (3, 4). This species is maintained in an autoinhibited conformation by a pseudosubstrate segment that blocks the substrate-binding cavity, a conformation that also protects the priming sites of PKC from dephosphorylation. The inactive species are localized throughout the cell, often tethered to scaffold proteins (5). This processing by phosphorylation is constitutive and required to protect PKC from degradation; unphosphorylated protein is rapidly degraded (1). Second, binding to lipid second messengers allosterically controls the enzyme by facilitating the release of the autoinhibitory pseudosubstrate segment from the substrate-binding cavity (6). Thus, this conformational transition is acutely controlled by activation of receptors that signal using diacylglycerol as the second messenger. The membranebound conformation has an increased sensitivity to phosphatases by 2 orders of magnitude The PKC family is composed of nine genes (9, 10), of which the conventional (␣, the alternatively spliced ␤I and ␤II, and brain-enriched ␥) and novel (␦, ⑀, , and hematopoietic-enriched ) isozymes are matured by phosphorylation on three conserved sites originally identified in PKC ␤II: the activation loop at the entrance to the active site and two C-terminal sites, the turn motif and hydrophobic motif (3). Atypical PKC isozymes ( and ) are also phosphorylated at the activation loop and turn motif, but a phosphomimetic is present at the hydrophobic motif. The upstream kinase PDK-1 4 catalyzes the phosphorylation of the activation loop of all PKC isozymes, an event that correctly aligns residues in the active site for catalysi

    Responsive glyco-poly(2-oxazoline)s: synthesis, cloud point tuning, and lectin binding

    Get PDF
    A new sugar-substituted 2-oxazoline monomer was prepared using the copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. Its copolymerization with 2-ethyl-2-oxazoline as well as 2-(dec-9-enyl)-2-oxazoline, yielding well-defined copolymers with the possibility to tune the properties by thiol-ene "click" reactions, is described. Extensive solubility studies on the corresponding glycocopolymers demonstrated that the lower critical solution temperature behavior and pH-responsiveness of these copolymers can be adjusted in water and phosphate-buffered saline (PBS) depending on the choice of the thiol. By conjugation of 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose and subsequent deprotection of the sugar moieties, the hydrophilicity of the copolymer could be increased significantly, allowing a cloud-point tuning in the physiological range. Furthermore, the binding capability of the glycosylated copoly(2-oxazoline) to concanavalin A was investigated
    corecore