1,492 research outputs found

    Coldwater reattachment of colonial tunicate Didemnum vexillum fragments to natural (eelgrass) and artificial (plastic) substrates in New England

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    © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Aquatic Invasions 9 (2014): 105–110, doi:10.3391/ai.2014.9.1.09.The colonial tunicate Didemnum vexillum Kott, 2002, was introduced to New England in the 1980s and by 2000 it was widespread. This highly invasive species spreads by larval release and fragmentation. We tested the ability of D. vexillum fragments to reattach to natural (eelgrass Zostera marina (Linnaeus, 1753)) and artificial (plastic container) substrates during late fall and early winter. On average, 77% of D. vexillum fragments reattached to eelgrass and plastic in water temperatures between 6 and 10°C. Eelgrass appeared to facilitate D. vexillum reattachment success in early winter but this tendency should be further investigated.Funding to Carman came from the US EPA RARE Program and USGS-WHOI Cooperative Agreement

    The effects of light pruning, irrigation and improved soil management on wine quality of the Vitis vinifera cv. Riesling

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    A number of yield improving viticultural practices were assessed in terms of their effect on wine quality. These were improved soil management, lighter pruning/higher trellis, irrigation and a control. In the first year a yield increase of 1.6 t /ha for the irrigation treatment had no significant effect on wine quality. A procedure is presented to assess judges for reliability, discrimination, variability and stability as part of analysis of the sensory results. Four judges were able to consistently identify lot differences

    Case–control, kin-cohort and meta-analyses provide no support for STK15 F31I as a low penetrance colorectal cancer allele

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    Recently, homozygosity for T91A single-nucleotide polymorphism (SNP) in the serine/threonine kinase (STK15) gene, which generates the substitution F31I has been proposed to increase the risk of a number of tumours including colorectal cancer (CRC). To further evaluate the relationship between STK15 F31I and risk of CRC, we genotyped 2558 CRC cases and 2680 controls for this polymorphism. We found no evidence that homozygosity for the STK15 31I genotype confers an increased risk of CRC (odds ratio=0.95, 95% confidence interval (CI): 0.74–1.24). We also conducted a kin-cohort analysis to assess risk among first-degree relatives of the CRC cases. The hazard ratio for I/I homozygotes compared to F/F homozygotes was 1.65 (95% CI: 0.39–3.17). A meta-analysis of our case–control data and three previous studies also provided no evidence of an elevated risk of CRC associated with homozygosity. These data provide no support for the hypothesis that sequence variation in STK15 defined by SNP F31I per se confers an elevated risk of CRC

    Rainbow Smelt (Osmerus mordax) Genomic Library and EST Resources

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    Genomic resources in rainbow smelt (Osmerus mordax) enable us to examine the genome duplication process in salmonids and test hypotheses relating to the fate of duplicated genes. They further enable us to pursue physiological and ecological studies in smelt. A bacterial artificial chromosome library containing 52,410 clones with an average insert size of 146 kb was constructed. This library represents an 11-fold average coverage of the rainbow smelt (O. mordax) genome. In addition, several complementary deoxyribonucleic acid libraries were constructed, and 36,758 sequences were obtained and combined into 12,159 transcripts. Over half of these transcripts have been identified, several of which have been associated with cold adaptation. These basic resources show high levels of similarity (86%) to salmonid genes and provide initial support for genome duplication in the salmonid ancestor. They also facilitate identification of genes important to fish and direct us toward new technologies for other studies in fish biology

    Spatial Variation of Diapycnal Diffusivity Estimated From Seismic Imaging of Internal Wave Field, Gulf of Mexico

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    Bright reflections are observed within the upper 1000~m of the water column along a seismic reflection profile that traverses the northern margin of the Gulf of Mexico. Independent hydrographic calibration demonstrates that these reflections are primarily caused by temperature changes associated with different water masses that are entrained into the Gulf along the Loop Current. The internal wave field is analyzed by automatically tracking 1171 reflections, each of which is greater than 2~km in length. Power spectra of the horizontal gradient of isopycnal displacement, ϕξx\phi_{\xi_x}, are calculated from these tracked reflections. At low horizontal wavenumbers (kx<102k_x < 10^{-2} cpm), ϕξxkx0.2±0.6\phi_{\xi_x} \propto k_x^{-0.2 \pm 0.6}, in agreement with hydrographic observations of the internal wave field. The turbulent spectral subrange is rarely observed. Diapycnal diffusivity, KK, is estimated from the observed internal wave spectral subrange of each tracked reflection using a fine-scale parametrization of turbulent mixing. Calculated values of KK vary between 10810^{-8} and 10410^{-4}~m2^{2}~s1^{-1} with a mean value of K4×106K \sim 4 \times 10^{-6}~m2^{2}~s1^{-1}. The spatial distribution of turbulent mixing shows that K107K \sim 10^{-7}~m2^{2}~s1^{-1} away from the shelf edge in the upper 300~m where stratification is strong. Mixing is enhanced by up to four orders of magnitude adjacent to the shoaling bathymetry of the continental slope. This overall pattern matches that determined by analyzing nearby suites of CTD casts. However, the range of values recovered by spectral analysis of the seismic image is greater as a consequence of significantly better horizontal resolution

    HIV-1 Vpu Protein Mediates the Transport of Potassium in Saccharomyces cerevisiae

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    Human immunodeficiency virus type 1 (HIV-1) Vpu is an integral membrane protein that belongs to the viroporin family. Viroporins interact with cell membranes, triggering membrane permeabilization and promoting release of viral particles. In vitro electrophysiological methods have revealed changes in membrane ion currents when Vpu is present; however, in vivo the molecular mechanism of Vpu at the plasma membrane is still uncertain. We used the yeast Saccharomyces cerevisiae as a genetic model system to analyze how Vpu ion channel impacts cellular homeostasis. Inducible expression of Vpu impaired cell growth, suggesting that this viral protein is toxic to yeast cultures. This toxicity decreased with extracellular acidic pH. Also, Vpu toxicity diminished as the extracellular K(+) concentration was increased. However, expression of the Vpu protein suppresses the growth defect of K(+) uptake-deficient yeast (Δtrk1,2). The phenotype rescue of these highly hyperpolarized cells was almost total when they were grown in medium supplemented with high concentrations of KCl (100 mM) at pH 7.0 but was significantly reduced when the extracellular K(+) concentration or pH was decreased. These results indicate that Vpu has the ability to modify K(+) transport in both yeast strains. Here, we show also that Vpu confers tolerance to the aminoglycoside antibiotic hygromycin B in Δtrk1,2 yeast. Our results suggest that Vpu interferes with cell growth of wild-type yeast but improves proliferation of the hyperpolarized trk1,2 mutant by inducing plasma membrane depolarization. Furthermore, evaluation of the ion channel activity of the Vpu protein in Δtrk1,2 yeast could aid in the development of a high-throughput screening assay for molecules that target the retroviral protein.This study was supported by Grants PI PI05/00013 and PI08/0912 from Fondo de Investigación Sanitaria. L.H. and N.M. were holders of Predoctoral Fellowships from Instituto de Salud Carlos III.S
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