Sewanee: The University of the South

About: Sewanee: The University of the South is a education organization based out in Sewanee, Tennessee, United States. It is known for research contribution in the topics: Population & Species richness. The organization has 8995 authors who have published 14790 publications receiving 320138 citations. The organization is also known as: Sewanee & The University of the South.

Repair of a specific double-strand break generated within a mammalian chromosome by yeast endonuclease I-SceI.

Abstract: We established a mouse Ltk- cell line that contains within its genome a herpes simplex virus thymidine kinase gene (tk) that had been disrupted by the insertion of the recognition sequence for yeast endonuclease I-SceI. The artificially introduced 18 bp I-SceI recognition sequence was likely a unique sequence in the genome of the mouse cell line. To assess whether an induced double-strand break (DSB) in the genomic tk gene would be repaired preferentially by gene targeting or non-homologous recombination, we electroporated the mouse cell line with endonuclease I-SceI alone, one of two different gene targeting constructs alone, or with I-SceI in conjunction with each of the two targeting constructs. Each targeting construct was, in principle, capable of correcting the defective genomic tk sequence via homologous recombination. tk+ colonies were recovered following electroporation of cells with I-SceI in the presence or absence of a targeting construct. Through the detection of small deletions at the I-SceI recognition sequence in the mouse genome, we present evidence that a specific DSB can be introduced into the genome of a living mammalian cell by yeast endonuclease I-SceI. We further report that a DSB in the genome of a mouse Ltk- cell is repaired preferentially by non-homologous end-joining rather than by targeted homologous recombination with an exogenous donor sequence. The potential utility of this system is discussed.

Volume IV. The DUNE far detector single-phase technology

Abstract: The preponderance of matter over antimatter in the early universe, the dynamics of the supernovae that produced the heavy elements necessary for life, and whether protons eventually decay—these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our universe, its current state, and its eventual fate. DUNE is an international world-class experiment dedicated to addressing these questions as it searches for leptonic charge-parity symmetry violation, stands ready to capture supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. Central to achieving DUNE's physics program is a far detector that combines the many tens-of-kiloton fiducial mass necessary for rare event searches with sub-centimeter spatial resolution in its ability to image those events, allowing identification of the physics signatures among the numerous backgrounds. In the single-phase liquid argon time-projection chamber (LArTPC) technology, ionization charges drift horizontally in the liquid argon under the influence of an electric field towards a vertical anode, where they are read out with fine granularity. A photon detection system supplements the TPC, directly enhancing physics capabilities for all three DUNE physics drivers and opening up prospects for further physics explorations. The DUNE far detector technical design report (TDR) describes the DUNE physics program and the technical designs of the single- and dual-phase DUNE liquid argon TPC far detector modules. Volume IV presents an overview of the basic operating principles of a single-phase LArTPC, followed by a description of the DUNE implementation. Each of the subsystems is described in detail, connecting the high-level design requirements and decisions to the overriding physics goals of DUNE.

Evidence for scale- and disturbance-dependent trait assembly patterns in dry semi-natural grasslands

Abstract: 1. The mechanisms driving nonrandom assembly patterns in plant communities have long been of interest in ecological research. Competing ecological theories predict that coexisting species may either be more functionally dissimilar than expected by chance (with functional divergence' mainly reflecting niche differentiation) or be functionally more similar than expected (with functional convergence' reflecting either the outcome of environmental filtering or weaker-competitor exclusion effects). Assembly patterns are usually assessed at a single scale and disturbance regime, whereas considering different spatial scales and disturbance regimes may clarify the underlying assembly mechanisms. 2. We tested the prediction that convergence and divergence are scale- and disturbance- dependent in grazed and abandoned species-rich dry grasslands within a 22km(2) landscape in south-eastern Sweden. Convergence and divergence were tested for plant species' traits and phylogenetic relationships at three nested spatial scales: within 412 plots (50x50cm, divided into 10x10cm subplots), within 117 grassland patches (from 0.02 to 11.63ha) and within the whole landscape (across patches). 3. At the finest scale (10x10cm subplots within plots), coexisting species were more different than expected by chance (divergence), both functionally and phylogenetically, suggesting niche differentiation. At the intermediate scale (50x50cm plots within patches), coexisting species showed convergence, suggesting environmental filtering. No significant deviations from random expectations were detected at the broadest scale (patches within the 22km(2) landscape) - suggesting the prevalence of dispersal limitation at this scale. The fact that nonrandom patterns were particularly evident under grazed conditions is consistent with the prediction that assembly patterns are disturbance dependent. 4. Synthesis. This study shows that multiple trait-based assembly processes operate simultaneously in species-rich communities, across spatial scales and disturbance regimes. The results support earlier theoretical predictions that divergence between coexisting species may be an important driver of community assembly, particularly at finer spatial scales, where species compete for the same local resources. In contrast, environmental filtering is expected at broader spatial scales, where species growing in particular environmental conditions share traits that are adaptive under those conditions. Within given habitat types, dispersal limitation may, however, override environmental filtering at increasing spatial scales of observation. (Less)

Sexual dysfunction induced by serotonin reuptake antidepressants.

Abstract: Serotonin reuptake inhibitor (SRI) antidepressants have been associated with sexual dysfunction, though there have been few prospective reports specifically examining this problem. The purpose of this study was to determine if three SRIs affected sexual function in patients with an anxiety disorder or major depressive disorder over a 3-month period. Sixty-one patients were evaluated for at least 2 months in a prospective study of the effects of fluoxetine, sertraline, and paroxetine on five aspects of sexual function: libido, erection/lubrication, orgasm quality, orgasm delay, and sexual frequency. Measurements were made at baseline and at each month on visual analog scales. For men and women, orgasm quality was lower and orgasm delay longer at Months 1, 2, and 3 compared with baseline (p < .001). Erection scores were lower over time (p < .02) but this change was less dramatic. Lubrication, libido, and sexual frequency were not appreciably changed over 3 months. Anorgasmia was significantly more common in women than men at Months 1 and 2. Orgasm appears to be a primary sexual function affected by SRIs.