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51.
Pim van Hooft Herbert HT Prins Wayne M Getz Anna E Jolles Sipke E van Wieren Barend J Greyling Paul D van Helden Armanda DS Bastos 《BMC evolutionary biology》2010,10(1):106
Background
The Y-chromosomal diversity in the African buffalo (Syncerus caffer) population of Kruger National Park (KNP) is characterized by rainfall-driven haplotype frequency shifts between year cohorts. Stable Y-chromosomal polymorphism is difficult to reconcile with haplotype frequency variations without assuming frequency-dependent selection or specific interactions in the population dynamics of X- and Y-chromosomal genes, since otherwise the fittest haplotype would inevitably sweep to fixation. Stable Y-chromosomal polymorphism due one of these factors only seems possible when there are Y-chromosomal distorters of an equal sex ratio, which act by negatively affecting X-gametes, or Y-chromosomal suppressors of a female-biased sex ratio. These sex-ratio (SR) genes modify (suppress) gamete transmission in their own favour at a fitness cost, allowing for stable polymorphism. 相似文献52.
Immunoglobulin-positive cells from the gland of harder and bone marrow of the chicken 总被引:1,自引:0,他引:1
Cells were collected from the gland of Harder (GH) and bone marrow (BM) of 14-, 21- and 32-week-old birds and were incubated with an 125I-labeled rabbit anti-chicken Ig (IgG and IgM) serum. At 14 weeks of age the percentage of Ig+ small lymphocytes (SL) in the GH and BM was similar. However, by 21 weeks of age Ig+ SL in BM had increased to approximately 19% of total lymphocytes while the Ig+ SL in the GH represented less than 1.7% of the lymphocyte pool. A marked drop in the number of Ig+ SL in BM occurred by 32 weeks of age. These data suggest that either the BM may be dependent on the bursa for maintenance of its Ig+ SL or it is unable to produce in situ or maintain Ig+ SL with age. In the GH the predominant cell was the plasma cell (PC). Labeled PC (> 20 grains) exceeded 80% of the total PC pool in the GH. These data contrast with the apparent deficiency of Ig receptors on murine PC. The maintenance of a large number of PC in the GH without the presence of Ig+ SL illustrates the uniqueness of this gland. 相似文献
53.
54.
E E Stinson S F Osman C N Huhtanen D D Bills 《Applied and environmental microbiology》1978,36(4):620-622
Eight yeast strains were used in three typical American processes to ferment apple juice containing 15 mg of added patulin per liter. Patulin was reduced to less than the minimum detectable level of 50 microgram/liter in all but two cases; in all cases, the level of patulin was reduced by over 99% during alcoholic fermentation. In unfermented samples of apple juice, the concentration of added patulin declined by only 10% when the juice was held for 2 weeks, a period equivalent to the time required for fermentation. 相似文献
55.
Peters BA Kan Z Sebisanovic D Pujara K Wang Z Hong P Chow B Stinson J Carlton VE Pham TQ Stern H Waring P Hillan KJ Eberhard DA de Sauvage F Zheng J Faham M Seshagiri S 《Nature methods》2007,4(9):713-715
The discovery of somatic mutations in cancer tissue is extremely laborious, time-consuming and costly. In an evaluation comparing mismatch repair detection (MRD) against Sanger sequencing for somatic-mutation detection, we found that MRD had a specificity of 96% and a sensitivity of 92%. Our results showed that MRD is a robust and cost-effective alternative to Sanger sequencing for identifying somatic mutations in human tumors. 相似文献
56.
Leishmania braziliensis, growing axenically at 26 C and transferred to 34 C, changes within 3 hr from the long slender motile promastigote form to an ellipsoidal form with a nonmotile flagellum. This transformation is reversible for heat treatments of up to 12 hr. In this study we show by light microscopic measurements that the cells decrease in length and increase in diameter at constant volume. Quantitative morphometry of electron micrographs further demonstrates that: the distance between nucleus and kinetoplast decreases; the kinetoplast enlarges slightly; the distance between adjacent subpellicular microtubules decreases; and that after 3 hr of heat treatment there is no change in mitochondrial morphology, but after 6 hr of heat treatment the mitochondria lose their cristae and no longer possess a clearly defined double membrane. These observations are compared with the morphological changes that occur normally in the gut of a sandfly and in the in vivo transformation occurring during infection of the mammalian host and of macrophage cultures. 相似文献
57.
Ramnarayan S. Randad Lucyna Lubkowska Michael A. Eissenstat Sergei V. Gulnik Betty Yu T. Narayana Bhat David J. Clanton Tyra House Sherman F. Stinson John W. Erickson 《Bioorganic & medicinal chemistry letters》1998,8(24):1679-3542
A series of novel unsymmetrical anthranilamide-containing HIV protease inhibitors was designed. The structure-activity studies revealed a series of potent P2–P3′ inhibitors that incorporate an anthranilamide group at the P2′ position. A reduction in molecular weight and lipophilicity is achieved by a judicious choice of P2 ligands (i.e., aromatic, heteroaromatic, carbamate, and peptidic). A systematic investigation led to the 5-thiazolyl carbamate analog 8m, which exhibited a favorable Cmax/EC50 ratio (>30), plasma half-life (>8 h), and potent in vitro antiviral activity (EC50 = 0.2 uM). 相似文献
58.
Eight yeast strains were used in three typical American processes to ferment apple juice containing 15 mg of added patulin per liter. Patulin was reduced to less than the minimum detectable level of 50 microgram/liter in all but two cases; in all cases, the level of patulin was reduced by over 99% during alcoholic fermentation. In unfermented samples of apple juice, the concentration of added patulin declined by only 10% when the juice was held for 2 weeks, a period equivalent to the time required for fermentation. 相似文献
59.
60.
Lawrence R. Phillips Chris Bramhall John Buckley Tracy Wolfe Tyra L. House Sherman F. Stinson 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2000,741(2):851
During the course of our study to develop analytical methodology for quantitating the investigative antitumor agent 5-amino-2-(4-amino-3-fluorophenyl)-6,8-difluoro-7-methyl-4H-1-benzopyran-4-one (DAF; NSC 686288) in plasma, a significant concentration of a metabolite was observed in a post-dosed rat. The results of electron-ionization (EI) mass spectrometric analysis of the metabolite suggested that N-acetylation had occurred, but, interestingly, that only one of the compound’s two primary amino groups had been transformed. Comparing the mass spectra and gas chromatographic retention times of a mono-acetylated sample of DAF and that of the metabolite showed both to be the same. A retro-Diels–Alder (RDA) fragmentation of the B ring of DAF results in formation of two abundant product ions, each retaining one of the amino groups. The EI mass spectrum of mono-N-acetamido-d3 DAF shows loss of ketene-d2, leading to formation of an –NHD group. The ensuing RDA fragmentation easily identifies which of the two product ions contains the deuterium, thereby allowing us to assign the site of N-acetylation as the amino group on ring C (the 4′ position) of DAF. 相似文献