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61.
本文记述了我国瓦蛛属三新纪录种,即突褶瓦蛛Walckenaeria sounkyoensis、钉角瓦蛛Walckenaeria claviornis、霍氏瓦蛛Walckenaeria holmi。本文量度单位:mm。标本保存在长春市白求恩医科大学生物教研室。 相似文献
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Identification and analysis of discrete functional domains in the pro region of pre-pro-transforming growth factor beta 1 总被引:3,自引:0,他引:3 下载免费PDF全文
A series of site-specific insertion and deletion mutants was prepared in the pro domain of transforming growth factor beta 1 (TGF beta 1) encoded by simian TGF beta 1 cDNA. These mutants were transiently expressed in COS-1 cells and the ability of each to be properly processed, folded correctly, and secreted was determined by immunoblot analysis of cells and culture supernatants. Insertions in regions corresponding to amino acid residues 50, 154, and 170 blocked secretion; culture supernatants from COS-1 cells showed no immunologically reactive proteins, whereas intact cells contained high levels of the mutant polypeptides. Insertions in the middle portion of the pro domain at residues 81, 85, and 144 affected disulfide maturation of the mature TGF beta 1. An insertion at residue 110, on the other hand, appeared to destabilize the mature TGF beta 1 polypeptide, resulting in degraded growth factor. Relatively small (10 amino acids) to large (125 amino acids) deletion mutations in the pro domain of TGF beta 1, when expressed as the full-length pre-pro-TGF beta 1, appeared to block secretion. By contrast, if the pro domain (designated beta 1-latency-associated peptide [beta 1-LAP]) was expressed independently, deletion mutants in the region 40-110 were readily secreted by the COS-1 cells, whereas deletions in residues 110-210 either destabilized the structure of the protein or blocked its intracellular transport. Cross-linking assays employing radioiodinated TGF beta 1 and biological assays indicate that residues 50-85 of beta 1-LAP are required for association with mature TGF beta 1. 相似文献
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光敏反应对过氧化氢酶的影响 总被引:1,自引:0,他引:1
林植芳 《生物化学与生物物理进展》1991,18(6):435-438
光氧化反应中,纯过氧化氢酶活性受光敏化剂血卟啉Ⅳ和核黄素的抑制。随光敏化剂浓度增高及照光时间延长,抑制程度加大。酶与光敏化剂反应后吸收光谱位移,峰形改变。紫外差示吸收光谱出现229nm负峰(血卟啉)和236—240nm峰(核黄素)。结果表明酶活的抑制与其蛋白构象的变化相关。 相似文献
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Tall fescue (Festuca arundinacea Schreb.) and white clover (Trifoliumrepens L.) were examined for Se assimilation and nutrient elementuptake. Substantial Se tolerance difference was found betweenthe two species. An inverse relationship between Se accumulationand Se tolerance suggests an exclusion mechanism that restrictsSe uptake by the plant with greater Se tolerance. A positiverelationship between the increase of protein Se concentrationand growth inhibition in the plants suggests that assimilationof Se into proteins is responsible for the Se toxic effect andthis study indicates that the antagonistic effect of sulphateis responsible for reducing Se toxicity at the protein level.No evidence that a Se exclusion mechanism which excludes Sefrom incorporating into protein, such as that found in Astragalusspecies, plays any major role of Se tolerance in these two species. Under Se treatment, plant tissue Ca concentration was increased,but P concentration was decreased. A higher Fe concentrationwas found in white clover which increased with increasing tissueSe concentration. Copper, Mn, and Zn concentrations only increasedin the white clover under conditions of severe growth inhibition. Key words: Tall fescue, white clover, selenium assimilation, selenium exclusion, tolerance, nutrient uptake 相似文献
65.
本文报告刚刺颚口线虫Gnathostoma hispidum和棘颚口线虫Gnathostoma spinigerum流行学和动物实验。证明我国有40种动物充当它们的第一、二中间宿主和转续宿主,其中30种是这两种病源共同宿主。首次报告猕猴Macaca mulatta可作刚刺颚口线虫的第二中间宿主和转续宿主。用刚刺颚口线虫晚第三期幼虫经皮肤感染家猫和小白鼠均得阳性。调查和实验结果表明刚刺颚口线虫和棘颚口线虫的生物学和流行学特性十分相似,显示它们都是人兽共患的寄生虫。文中讨论刚刺颚口线虫的传播途径和人体感染问题。 相似文献
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