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排序方式: 共有918条查询结果,搜索用时 31 毫秒
901.
902.
Nigel K. Spurr Simon Cox Stephen P. Bryant John Attwood Elizabeth B. Robson Denis C. Shields Todd Steinbrueck Trefor Jenkins Jeffrey C. Murray Kenneth K. Kidd Marshall L. Summar Petros Tsipouras Andries E. Retief Torben A. Kruse Allen E. Bale Gilles Vergnaud James L. Weber O.W. McBride Helen Donis-Keller Raymond L. White 《Genomics》1992,14(4):1055-1063
This paper describes the Centre d'Etude du Polymorphisme Humain (CEPH) consortium linkage map of chromosome 2. The map contains 36 loci defined by genotyping generated from the CEPH family DNAs. A total of 73 different markers were typed by 14 contributing laboratories; of these, 36 loci are ordered on the map with likelihood support of at least 1000:1. Markers are placed along the length of the chromosome but no markers were available to anchor the map at either telomere or the centromere. Multilocus linkage analysis has produced male, female, and sex-averaged maps extending for 261, 430, and 328 cM, respectively. The sex-averaged map contains five intervals greater than 15 cM and the mean genetic distance between the 36 uniquely placed loci is 9.1 cM. 相似文献
903.
- Although the amino acid composition of fishes and some marine invertebrates varies among taxa and systems, similar information is lacking for freshwater invertebrates. The objectives were to characterise and compare the amino acid composition among different aquatic species, dietary habits, and environmental conditions.
- Benthic macroinvertebrates from different functional feeding groups (FFG), bulk zooplankton, biofilm, and fishes representing 12 families (21 genera or species) were collected from temperate lakes in eastern Canada during the summers of 2013 and 2014. Fifteen protein-bound amino acids, including thiols, were measured in whole invertebrates, biofilm, or fish muscle. We hypothesised that the amino acid composition will differ among species and systems.
- Multiple discriminant analyses revealed significant differences in the amino acid composition among species—based on varying percentages of cysteine (as cysteic acid) and histidine—and among FFG/trophic designations—based on histidine and lysine—where the primary consumers were more variable than the predators.
- Overall, the results suggest that patterns were based on phylogenetics, biological characteristics, and the FFG/trophic designations of biota.
- The within-taxon variability in composition was also related to differences among lakes. Characteristics of their environment, including lake pH and the food web structure (abundance and composition of taxa), probably influenced their dietary habits and amino acid composition of diet.
- These results expand the currently limited knowledge of the biochemical composition of freshwater biota and provide impetus for further studies on nutritional values in predator-prey relationships, trophic guilds, and the biomagnification of protein-bound contaminants through food webs.
904.
Jack Ferguson Steven Dunn Angus Best Jeremy Mirza Benita Percival Megan Mayhew Oliver Megram Fiona Ashford Thomas White Emma Moles-Garcia Liam Crawford Tim Plant Andrew Bosworth Michael Kidd Alex Richter Jonathan Deeks Alan McNally 《PLoS biology》2021,19(4)
Lateral flow devices (LFDs) are quickly being implemented for use in large-scale population surveillance programs for SARS-CoV-2 infection in the United Kingdom. These programs have been piloted in city-wide screening in the city of Liverpool and are now being rolled out to support care home visits and the return home of University students for the Christmas break. Here, we present data on the performance of LFDs to test almost 8,000 students at the University of Birmingham between December 2 and December 9, 2020. The performance is validated against almost 800 samples using PCR performed in the University Pillar 2 testing lab and theoretically validated on thousands of Pillar 2 PCR testing results performed on low-prevalence care home testing samples. Our data show that LFDs do not detect infections presenting with PCR Ct values over 29 to 30 as determined using the Thermo Fisher TaqPath asssay. This may be of particular importance in detecting individuals that are either at the early, or late stages of infection, and reinforces the need for frequent, recurrent testing.Antigen-detecting lateral flow tests are faster than PCR tests in detecting SARS-CoV-2 infection and are being implemented for use in large-scale population surveillance in the UK. An evaluation of the performance of the lateral flow devices, validated using PCR, concludes that lateral flow devices do not detect infections presenting with higher PCR Ct values, reinforcing the need for frequent, recurrent testing. 相似文献
905.
906.
Karen A. Kidd Michael J. Paterson Michael D. Rennie Cheryl L. Podemski Dave L. Findlay Paul J. Blanchfield Karsten Liber 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2014,369(1656)
Endocrine-disrupting chemicals (EDCs) in municipal effluents directly affect the sexual development and reproductive success of fishes, but indirect effects on invertebrate prey or fish predators through reduced predation or prey availability, respectively, are unknown. At the Experimental Lakes Area in northwestern Ontario, Canada, a long-term, whole-lake experiment was conducted using a before-after-control-impact design to determine both direct and indirect effects of the synthetic oestrogen used in the birth control pill, 17α-ethynyloestradiol (EE2). Algal, microbial, zooplankton and benthic invertebrate communities showed no declines in abundance during three summers of EE2 additions (5–6 ng l−1), indicating no direct toxic effects. Recruitment of fathead minnow (Pimephales promelas) failed, leading to a near-extirpation of this species both 2 years during (young-of-year, YOY) and 2 years following (adults and YOY) EE2 additions. Body condition of male lake trout (Salvelinus namaycush) and male and female white sucker (Catostomus commersonii) declined before changes in prey abundance, suggesting direct effects of EE2 on this endpoint. Evidence of indirect effects of EE2 was also observed. Increases in zooplankton, Chaoborus, and emerging insects were observed after 2 or 3 years of EE2 additions, strongly suggesting indirect effects mediated through the reduced abundance of several small-bodied fishes. Biomass of top predator lake trout declined by 23–42% during and after EE2 additions, most probably an indirect effect from the loss of its prey species, the fathead minnow and slimy sculpin (Cottus cognatus). Our results demonstrate that small-scale studies focusing solely on direct effects are likely to underestimate the true environmental impacts of oestrogens in municipal wastewaters and provide further evidence of the value of whole-ecosystem experiments for understanding indirect effects of EDCs and other aquatic stressors. 相似文献
907.
908.
909.
Glucocorticoids are known inhibitors of prostaglandin production. Prostaglandin E2 (PGE2) and prostacyclin (PGI2) are promoters of natriuresis and renin release. Excessive prostaglandin production, therefore, might contribute to the altered sodium balance and renin release observed in primary adrenal insufficiency. To test this hypothesis, sodium balance and prostaglandin production were measured in adrenalectomized rats and in animals receiving prostaglandin inhibitors or replacement dexamethasone. Compared to sham-operated controls, adrenalectomized rats had decreased two-day sodium balance and elevated plasma renin concentration (PRC), renal PGE2 production, and renal 6-ketoprostaglandin F1 alpha (6kPGF1 alpha, the nonenzymatic metabolite of PGI2); however, no appreciable change in aortic 6kPGF1 alpha production was observed. Dexamethasone given to adrenalectomized rats normalized PRC but had no effect on sodium balance or prostaglandin production. Likewise, prostaglandin inhibitors did not alter the sodium balance or decrease the PRC post adrenalectomy. These data confirm renal prostaglandin production is increased in adrenalectomized rats, but suggest that the elevation is not due directly to glucocorticoid deficiency. Further, PRC levels in adrenal insufficiency do not appear to be prostaglandin mediated. In conclusion, excessive renal prostaglandin production does not contribute to altered sodium balance or increased PRC in adrenalectomized rats. 相似文献
910.