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本文研究了中国广东汉族健康人群apoAI-CⅢ-AIV基因簇DNA限制性内切酶PstI、SstI和EcoRI片段长度多态性。其中等位基因P_1,P_2,S_1,S_2,R_1和R_2的频率分别为0.98,0.02,0.96,0.04,0.90和0.10。经卡方检验符合Hardy-Weinbery氏遗传平衡,与其他种族比较,本文结果显示中国广东汉族人P_2等位基因频率低于日本人、亚洲印第安人和高加索人,S_2等位基因频率低于日本人、菲律宾人、沙特阿拉伯人和亚洲印第安人,而与高加索人相近,R_2等位基因频率稍高于高加索人。不同种族间apoAI-CⅢ-AIV基因簇DNA多态频率无疑存在差异,这种差异可能是由于遗传漂变和自然选择单独或联合作用所致。对P_1、P_2,S_1、S_2和R_1、R_2构成的单倍型和连锁平衡程度进行了分析,结果显示这些单倍型处于连锁不平衡状态。 相似文献
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During Dictyostelium discoideum development, cell-cell communication is mediated through cyclic AMP (cAMP)-induced cAMP synthesis and secretion (cAMP signaling) and cell-cell contact. Cell-cell contact elicits cAMP secretion and modulates the magnitude of a subsequent cAMP signaling response (D. R. Fontana and P. L. Price, Differentiation 41:184-192, 1989), demonstrating that cell-cell contact and cAMP signaling are not independent events. To identify components involved in the contact-mediated modulation of cAMP signaling, amoebal membranes were added to aggregation-competent amoebae in suspension. The membranes from aggregation-competent amoebae inhibited cAMP signaling at all concentrations tested, while the membranes from vegetative amoebae exhibited a concentration-dependent enhancement or inhibition of cAMP signaling. Membrane lipids inhibited cAMP signaling at all concentrations tested. The lipids abolished cAMP signaling by blocking cAMP-induced adenylyl cyclase activation. The membrane lipids also inhibited amoeba-amoeba cohesion at concentrations comparable to those which inhibited cAMP signaling. The phospholipids and neutral lipids decreased cohesion and inhibited the cAMP signaling response. The glycolipid/sulfolipid fraction enhanced cohesion and cAMP signaling. Caffeine, a known inhibitor of cAMP-induced adenylyl cyclase activation, inhibited amoeba-amoeba cohesion. These studies demonstrate that endogenous lipids are capable of modulating amoeba-amoeba cohesion and cAMP-induced activation of the adenylyl cyclase. These results suggest that cohesion may modulate cAMP-induced adenylyl cyclase activation. Because the complete elimination of cohesion is accompanied by the complete elimination of cAMP signaling, these results further suggest that cohesion may be necessary for cAMP-induced adenylyl cyclase activation in D. discoideum. 相似文献
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Mechanisms of Mutagenesis by a Bulky DNA Lesion at the Guanine N7 Position 总被引:4,自引:1,他引:3 下载免费PDF全文
K. Sambamurti J. Callahan X. Luo C. P. Perkins J. S. Jacobsen M. Z. Humayun 《Genetics》1988,120(4):863-873
The RpII215 locus encodes the large subunit of RNA polymerase II (polII). Three of 22 RpII215 alleles cause a synergistic enhancement of the mutant phenotype elicited by mutations in the Ultrabithorax (Ubx) locus. We have recovered and analyzed three new mutations that suppress this enhancement. All three mutations map to the RpII215 locus. In addition to suppressing the Ubx enhancement of other RpII215 alleles, two of the new mutations, JH1 and WJK2, themselves enhance Ubx. RpII215 alleles can be placed into three classes based on their ability to enhance Ubx. Class I alleles, including Ubl, C4, C11, JH1, and WJK2, enhance Ubx when heterozygous with class II alleles, which include wild-type RpII215. Class III alleles, which include amorphic alleles, do not enhance Ubx. The third new mutation, WJK1, is a conditional amorphic allele, which behaves like a class III allele at 29 degrees but like a class II allele at 19 degrees. Another mutant phenotype is caused by certain RpII215 alleles, including all class I alleles. This phenotype is a synergistic enhancement of a mutant phenotype elicited by mutations at the Delta (Dl) locus. Unlike the enhancement of Ubx, the enhancement of Dl is not dependent upon antagonistic interactions between different classes of RpII215 alleles. 相似文献
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大豆下胚轴线粒体产生超氧物自由基的效率 总被引:4,自引:0,他引:4
大豆下胚轴线粒体在呼吸基质存在下,显著地增加了肾上腺素氧化速率,这种氧化速率能为外源SOD抑制,表明线粒体呼吸时产生分子氧的单电子还原成O_2(?)。亚线粒体颗粒产生O_2(?)的效率略高于线粒体。大豆下胚轴线粒体吸链内O_2(?)的产生为NADH所支持并与交替途径无关。表明分子氧单电子还原的部位可能是NADH-黄素蛋白和UbQ-Cyt.B。 相似文献
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A highly conserved clonotype has been identified within the repertoire of B cells specific for the negatively charged hapten phthalate. The prototype of this phthalate-specific clonotype is a primary-response hybridoma (2E9) that produces a mu,kappa anti-phthalate antibody. The 2E9 monoclonal antibody was found to share idiotypic determinants with several other independently-derived mu,kappa and gamma 1,kappa anti-phthalate monoclonal antibodies and with a significant proportion of conventional anti-phthalate antibodies derived from all of the BALB/c mice immunized with phthalate-keyhole limpet hemocyanin. Competitive RIA analysis of the 2E9 idiotypic relatedness between primary and secondary response antibodies was consistent with the hypothesis that the primary response mu,kappa antibodies represent a conserved germ-line product, whereas the secondary response to gamma 1,kappa antibodies reflect somatic variants of the 2E9 clonotype. Further analysis with a site-specific anti-idiotype reagent suggests that the idiotypic differences between mu,kappa and gamma 1,kappa monoclonal antibodies occur at positions outside of the combining site. Fine specificity analysis of the monoclonal antibodies expressing the 2E9 cross-reactive idiotype (CRI) also supports this hypothesis. Seven to 35% of the anti-phthalate antibodies after a single immunization with phthalate-KLH and 1 to 10% of the antibodies after a second immunization express the 2E9 CRI. The 2E9 CRI was also found in several other strains of mice, and its expression was associated exclusively with anti-phthalate antibodies. 相似文献
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The isolation, structure determination and synthesis of ergosta-5, 24(28), 25-trien-3 beta-ol, as well as the synthesis of its 28-14C analog--a possible biosynthetic precursor of several marine sterols--is described. 相似文献
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