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排序方式: 共有159条查询结果,搜索用时 62 毫秒
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Lisette Waits Stephanie Dunkle F. E. Wilkinson P. Moreau Keri Safranski T. Reust Dorothy M. Morré D. J. Morré 《Protoplasma》1990,154(1):8-15
Summary Transfer of radiolabeled lipids from dictyosome-like structures (DLS) from testis tubules of the guinea pig as donor to unlabeled plasma membrane from testis tubules immobilized on nitrocellulose as acceptor was studied in a completely cell-free system. As a general label for lipids of the donor DLS, isolated testis tubules were incubated with [14C]acetate. Time- and temperature-dependent transfer of [14C]acetate labeled constituents was observed in the cellfree system. However, despite the fact that phospholipids and other constituents were highly labeled in the donor fraction, primarily radioactive sterols were transferred to the plasma membrane acceptor vesicles. Transfer at 37°C represented 0.4 to 0.7% of the total radiolabeled cholesterol at 37°C but little or no transfer occurred at 4°C. The sterols transferred exhibited Chromatographic mobilities corresponding to those of cholesterol and lanosterol. Similar results were obtained with [14C]mevalonic acid. In subsequent experiments, cholesterol transfer from DLS to plasma membrane was demonstrated by incubation of DLS with [3H]squalene which was converted into sterol or with [14C]cholesterol. Transfer of sterols required ATP, but not cytosol, and was both time- and temperature-dependent. DLS were more effective than either endoplasmic reticulum or plasma membrane as the donor fraction. The results from the cell-free analysis suggest a possible functional role of the DLS in sterol biogenesis and transfer to the plasma membrane during spermatid development.Abbreviations DLS
dictyosome-like structure(s)
- PBS
phosphatebuffered saline
- HEPES
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- BSA
bovine serum albumin 相似文献
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P Taberlet S Griffin B Goossens S Questiau V Manceau N Escaravage L P Waits J Bouvet 《Nucleic acids research》1996,24(16):3189-3194
Our purpose was to identify an experimental procedure using PCR that provides a reliable genotype at a microsatellite locus using only a few picograms of template DNA. Under these circumstances, it is possible (i) that one allele of a heterozygous individual will not be detected and (ii) that PCR-generated alleles or 'false alleles' will arise. A mathematical model has been developed to account for stochastic events when pipetting template DNA in a very dilute DNA extract and computer simulations have been performed. Laboratory experiments were also carried out using DNA extracted from a bear feces sample to determine if experimental results correlate with the mathematical model. The results of 150 typing experiments are consistent with the proposed model. Based on this model and the level of observed false alleles, an experimental procedure using the multiple tubes approach is proposed to obtain reliable genotypes with a confidence level of 99%. This multiple tubes procedure should be systematically used when genotyping nuclear loci of ancient or forensic samples, museum specimens and hair or feces of free ranging animals. 相似文献
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Amanda R. Goldberg Courtney J. Conway David C. Tank Kimberly R. Andrews Digpal S. Gour Lisette P. Waits 《Ecology and evolution》2020,10(14):7627-7643
In herbivores, survival and reproduction are influenced by quality and quantity of forage, and hence, diet and foraging behavior are the foundation of an herbivore's life history strategy. Given the importance of diet to most herbivores, it is imperative that we know the species of plants they prefer, especially for herbivorous species that are at risk for extinction. However, it is often difficult to identify the diet of small herbivores because: (a) They are difficult to observe, (b) collecting stomach contents requires sacrificing animals, and (c) microhistology requires accurately identifying taxa from partially digested plant fragments and likely overemphasizes less‐digestible taxa. The northern Idaho ground squirrel (Urocitellus brunneus) is federally threatened in the United States under the Endangered Species Act. We used DNA metabarcoding techniques to identify the diet of 188 squirrels at 11 study sites from fecal samples. We identified 42 families, 126 genera, and 120 species of plants in the squirrel's diet. Our use of three gene regions was beneficial because reliance on only one gene region (e.g., only trnL) would have caused us to miss >30% of the taxa in their diet. Northern Idaho ground squirrel diet differed between spring and summer, frequency of many plants in the diet differed from their frequency within their foraging areas (evidence of selective foraging), and several plant genera in their diet were associated with survival. Our results suggest that while these squirrels are generalists (they consume a wide variety of plant species), they are also selective and do not eat plants relative to availability. Consumption of particular genera such as Perideridia may be associated with higher overwinter survival. 相似文献
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A road map for molecular ecology 总被引:1,自引:0,他引:1
Rose L. Andrew Louis Bernatchez Aurélie Bonin C. Alex. Buerkle Bryan C. Carstens Brent C. Emerson Dany Garant Tatiana Giraud Nolan C. Kane Sean M. Rogers Jon Slate Harry Smith Victoria L. Sork Graham N. Stone Timothy H. Vines Lisette Waits Alex Widmer Loren H. Rieseberg 《Molecular ecology》2013,22(10):2605-2626
The discipline of molecular ecology has undergone enormous changes since the journal bearing its name was launched approximately two decades ago. The field has seen great strides in analytical methods development, made groundbreaking discoveries and experienced a revolution in genotyping technology. Here, we provide brief perspectives on the main subdisciplines of molecular ecology, describe key questions and goals, discuss common challenges, predict future research directions and suggest research priorities for the next 20 years. 相似文献
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Agricultural intensification alters bat assemblage composition and abundance in a dynamic Neotropical landscape 下载免费PDF全文
The recent trend of agricultural intensification in tropical landscapes poses a new threat to biodiversity conservation. Conversion of previously heterogeneous agricultural landscapes to intensive plantation agriculture simplifies and homogenizes the landscape, reducing availability, and connectivity of natural habitat for native species. To assess the impact of agricultural intensification on bats, we characterized the bat assemblage in the Sarapiquí region of Costa Rica, where heterogeneous land uses are being converted to intensive, large‐scale pineapple plantations. In 2012 and 2013, we sampled bats in 20 remnant forest patches surrounded by varying proportions of pasture, mature forest, and pineapple and captured 1821 individual bats representing 39 species. We used ordination analyses to evaluate changes in species composition, where pineapple is the main component of the agricultural matrix. We identified landscape metrics specifically correlated with pineapple and used multiple linear regression to test their effects on bat species richness, diversity, and guild‐specific relative abundance. Results suggest pineapple expansion is driving changes in assemblage composition in remnant forest patches, resulting in new assemblages with higher proportions of frugivorous bats and lower proportions of insectivorous bats than in continuous mature forests. In addition, while pineapple does not diminish total bat species richness and diversity, the reduced forest cover and increased distance between forest patches in pineapple plantations has a significant negative impact on the relative abundance of insectivores. We also identify a potential threshold effect whereby patches surrounded by more than 50 percent forest can retain assemblage composition similar to that found in continuous mature forest. 相似文献
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Melanie A. Murphy Katherine C. Kendall Andrew Robinson Lisette P. Waits 《Conservation Genetics》2007,8(5):1219-1224
To establish longevity of faecal DNA samples under varying summer field conditions, we collected 53 faeces from captive brown
bears (Ursus arctos) on a restricted vegetation diet. Each faeces was divided, and one half was placed on a warm, dry field site while the other
half was placed on a cool, wet field site on Moscow Mountain, Idaho, USA. Temperature, relative humidity, and dew point data
were collected on each site, and faeces were sampled for DNA extraction at <1, 3, 6, 14, 30, 45, and 60 days. Faecal DNA sample
viability was assessed by attempting PCR amplification of a mitochondrial DNA (mtDNA) locus (∼150 bp) and a nuclear DNA (nDNA)
microsatellite locus (180–200 bp). Time in the field, temperature, and dew point impacted mtDNA and nDNA amplification success
with the greatest drop in success rates occurring between 1 and 3 days. In addition, genotyping errors significantly increased
over time at both field sites. Based on these results, we recommend collecting samples at frequent transect intervals and
focusing sampling efforts during drier portions of the year when possible. 相似文献
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