3,026 research outputs found

    Sex Differences in Recombination in Sticklebacks.

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    Recombination often differs markedly between males and females. Here we present the first analysis of sex-specific recombination in Gasterosteus sticklebacks. Using whole-genome sequencing of 15 crosses between G. aculeatus and G. nipponicus, we localized 698 crossovers with a median resolution of 2.3 kb. We also used a bioinformatic approach to infer historical sex-averaged recombination patterns for both species. Recombination is greater in females than males on all chromosomes, and overall map length is 1.64 times longer in females. The locations of crossovers differ strikingly between sexes. Crossovers cluster toward chromosome ends in males, but are distributed more evenly across chromosomes in females. Suppression of recombination near the centromeres in males causes crossovers to cluster at the ends of long arms in acrocentric chromosomes, and greatly reduces crossing over on short arms. The effect of centromeres on recombination is much weaker in females. Genomic differentiation between G. aculeatus and G. nipponicus is strongly correlated with recombination rate, and patterns of differentiation along chromosomes are strongly influenced by male-specific telomere and centromere effects. We found no evidence for fine-scale correlations between recombination and local gene content in either sex. We discuss hypotheses for the origin of sexual dimorphism in recombination and its consequences for sexually antagonistic selection and sex chromosome evolution

    Long-Lived Electron Capture Dissociation Product Ions Experience Radical Migration via Hydrogen Abstraction

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    To explore the mechanism of electron capture dissociation (ECD) of linear peptides, a set of 16-mer peptides were synthesized with deuterium labeled on the α-carbon position of four glycines. The ECD spectra of these peptides showed that such peptides exhibit a preference for the radical to migrate to the α-carbon position on glycine via hydrogen (or deuterium) abstraction before the final cleavage and generation of the detected product ions. The data show c-type fragment ions, ions corresponding to the radical cation of the c-type fragments, c·, and they also show c·-1 peaks in the deuterated peptides only. The presence of the c·-1 peaks is best explained by radical-mediated scrambling of the deuterium atoms in the long-lived, metastable, radical intermediate complex formed by initial electron capture, followed by dissociation of the complex. These data suggest the presence of at least two mechanisms, one slow, one fast. The abundance of H· and −CO losses from the precursor ion changed upon deuterium labeling indicating the presence of a kinetic isotope effect, which suggests that the values reported here represent an underestimation of radical migration and H/D scrambling in the observed fragments

    Mechanism of Ad5 Vaccine Immunity and Toxicity: Fiber Shaft Targeting of Dendritic Cells

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    Recombinant adenoviral (rAd) vectors elicit potent cellular and humoral immune responses and show promise as vaccines for HIV-1, Ebola virus, tuberculosis, malaria, and other infections. These vectors are now widely used and have been generally well tolerated in vaccine and gene therapy clinical trials, with many thousands of people exposed. At the same time, dose-limiting adverse responses have been observed, including transient low-grade fevers and a prior human gene therapy fatality, after systemic high-dose recombinant adenovirus serotype 5 (rAd5) vector administration in a human gene therapy trial. The mechanism responsible for these effects is poorly understood. Here, we define the mechanism by which Ad5 targets immune cells that stimulate adaptive immunity. rAd5 tropism for dendritic cells (DCs) was independent of the coxsackievirus and adenovirus receptor (CAR), its primary receptor or the secondary integrin RGD receptor, and was mediated instead by a heparin-sensitive receptor recognized by a distinct segment of the Ad5 fiber, the shaft. rAd vectors with CAR and RGD mutations did not infect a variety of epithelial and fibroblast cell types but retained their ability to transfect several DC types and stimulated adaptive immune responses in mice. Notably, the pyrogenic response to the administration of rAd5 also localized to the shaft region, suggesting that this interaction elicits both protective immunity and vector-induced fevers. The ability of replication-defective rAd5 viruses to elicit potent immune responses is mediated by a heparin-sensitive receptor that interacts with the Ad5 fiber shaft. Mutant CAR and RGD rAd vectors target several DC and mononuclear subsets and induce both adaptive immunity and toxicity. Understanding of these interactions facilitates the development of vectors that target DCs through alternative receptors that can improve safety while retaining the immunogenicity of rAd vaccines

    The anxiolytic effects of cognitive behavior therapy for insomnia: preliminary results from a web-delivered protocol

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    Though the efficacy of cognitive behavior therapy for insomnia (CBTI) is well-established, the paucity of credentialed providers hinders widespread access. Further, the impact of alternatives such as web-delivered CBTI has not been adequately tested on common insomnia comorbidities such as anxiety. Therefore, we assessed the impact of an empirically validated web-delivered CBTI intervention on insomnia and comorbid anxiety symptoms. A sample of 22 adults (49.8±13.5 yo; 62.5% female) with DSM-5 based insomnia were randomized to either an active CBTI treatment group (n = 13) or an information-control (IC) group (n = 9). Participants in the CBTI group underwent a standard CBTI program delivered online by a 'virtual' therapist, whereas the IC group received weekly 'sleep tips' and general sleep hygiene education via electronic mail. All participants self-reported sleep parameters, including sleep onset latency (SOL), insomnia symptoms per the Insomnia Severity Index (ISI), and anxiety symptoms per the Beck Anxiety Inventory (BAI) at both baseline as well as follow- up assessment one week post-treatment. There were no significant differences between the CBTI and IC groups on baseline measures. The CBTI group showed significantly larger reductions in BAI scores (t = 2.6; p < .05; Cohen's d = .8) and ISI scores (t = 2.1; p < .05; Cohen's d = .9) at follow-up than did the IC group. Further, changes in SOL from baseline (62.3±44.0 minutes) to follow-up (22.3±14.4 minutes) in the CBTI group were also significantly greater (t = 2.3; p < .05; Cohen's d = .9) than in the IC group (baseline: 55.0±44.2 minutes; follow-up: 50.±60.2 minutes).This study offers preliminary evidence that a web-delivered CBTI protocol with minimal patient contact can improve comorbid anxiety symptoms among individuals with insomnia

    2,3,10,11-Tetra­meth­oxy-6,7,14,15-tetra­hydro-6,14-methano­cyclo­octa­[1,2-b;5,6-b′]diquinoline

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    The racemic title compound, C27H26N2O4, crystallizes with its central carbon bridge on a twofold axis. It forms parallel chains of mol­ecules utilizing aryl offset face–face inter­actions with an interplanar distance of about 3.5 Å. These chains associate further by means of pairs of O—CH2—H⋯π (with H–ring distances ranging from 2.69 to 2.95 Å) and O—CH2—H⋯N motifs. The meth­oxy groups in this structure are coplanar with the aromatic rings to which they are attached. This is recognized as being common behaviour amongst aromatic meth­oxy compounds

    A functionally specialized population of mucosal CD103+ DCs induces Foxp3+ regulatory T cells via a TGF-β– and retinoic acid–dependent mechanism

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    Foxp3+ regulatory T (T reg) cells play a key role in controlling immune pathological re actions. Many develop their regulatory activity in the thymus, but there is also evidence for development of Foxp3+ T reg cells from naive precursors in the periphery. Recent studies have shown that transforming growth factor (TGF)-β can promote T reg cell development in culture, but little is known about the cellular and molecular mechanisms that mediate this pathway under more physiological conditions. Here, we show that after antigen activation in the intestine, naive T cells acquire expression of Foxp3. Moreover, we identify a population of CD103+ mesenteric lymph node dendritic cells (DCs) that induce the devel opment of Foxp3+ T reg cells. Importantly, promotion of T reg cell responses by CD103+ DCs is dependent on TGF-β and the dietary metabolite, retinoic acid (RA). These results newly identify RA as a cofactor in T reg cell generation, providing a mechanism via which functionally specialized gut-associated lymphoid tissue DCs can extend the repertoire of T reg cells focused on the intestine

    High Sensitivity Multi-Axes Rotation Sensing Using Large Momentum Transfer Point Source Atom Interferometry

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    A point source interferometer (PSI) is a device where atoms are split and recombined by applying a temporal sequence of Raman pulses during the expansion of a cloud of cold atoms behaving approximately as a point source. The PSI can work as a sensitive multi-axes gyroscope that can automatically filter out the signal from accelerations. The phase shift arising from the rotations is proportional to the momentum transferred to each atom from the Raman pulses. Therefore, by increasing the momentum transfer, it should be possible to enhance the sensitivity of the PSI. Here, we investigate the degree of enhancement in sensitivity that could be achieved by augmenting the PSI with large momentum transfer (LMT) employing a sequence of many Raman pulses with alternating directions. We analyze how factors such as Doppler detuning, spontaneous emission, and the finite initial size of the atomic cloud compromise the advantage of LMT and how to find the optimal momentum transfer under these limitations, with both the semi-classical model and a model under which the motion of the center of mass of each atom is described quantum mechanically. We identify a set of realistic parameters for which LMT can improve the PSI by a factor of nearly 40

    A Mycobacterium ESX-1–Secreted Virulence Factor with Unique Requirements for Export

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    Specialized secretion systems of pathogenic bacteria commonly transport multiple effectors that act in concert to control and exploit the host cell as a replication-permissive niche. Both the Mycobacterium marinum and the Mycobacterium tuberculosis genomes contain an extended region of difference 1 (extRD1) locus that encodes one such pathway, the early secretory antigenic target 6 (ESAT-6) system 1 (ESX-1) secretion apparatus. ESX-1 is required for virulence and for secretion of the proteins ESAT-6, culture filtrate protein 10 (CFP-10), and EspA. Here, we show that both Rv3881c and its M. marinum homolog, Mh3881c, are secreted proteins, and disruption of RD1 in either organism blocks secretion. We have renamed the Rv3881c/Mh3881c gene espB for ESX-1 substrate protein B. Secretion of M. marinum EspB (EspBM) requires both the Mh3879c and Mh3871 genes within RD1, while CFP-10 secretion is not affected by disruption of Mh3879c. In contrast, disruption of Mh3866 or Mh3867 within the extRD1 locus prevents CFP-10 secretion without effect on EspBM. Mutants that fail to secrete only EspBM or only CFP-10 are less attenuated in macrophages than mutants failing to secrete both substrates. EspBM physically interacts with Mh3879c; the M. tuberculosis homolog, EspBT, physically interacts with Rv3879c; and mutants of EspBM that fail to bind Mh3879c fail to be secreted. We also found interaction between Rv3879c and Rv3871, a component of the ESX-1 machine, suggesting a mechanism for the secretion of EspB. The results establish EspB as a substrate of ESX-1 that is required for virulence and growth in macrophages and suggests that the contribution of ESX-1 to virulence may arise from the secretion of multiple independent substrates
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