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排序方式: 共有218条查询结果,搜索用时 31 毫秒
1.
SCE在鹌鹑胚胎细胞间的分布为Poisson分布;在染色体间的分布是非随机的,与染色体的相对长度成正相关(P<0.05),但也不完全按各染色体的相对长度分布。着丝粒区的SCE相对很高,按染色体的相对长度分布。胚胎的不同性别对每个细胞的SCE平均值无显著影响,但对性染色体Z上的SCE是否有影响还不能做出肯定的结论。 相似文献
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为了验证转基因烟草中表达的外壳蛋白(CP)能够重新包被侵入的烟草花叶病毒(TMV)的假设,利用抗原表位标记的方法观察CP亚单位在病毒5′端的交换。通过PCR 方法将来源于鼠肝炎病毒(MHV) S蛋白的两个小肽段(11 a.a.和15 a.a.)的DNA序列分别插入TMV-U1 CP基因邻近3′端的两个位点,并构建了带有外源序列的TMV 侵染克隆V9 (11 a.a.)和E15 (15 a.a.)。通过体外转录反应,得到V9 RNA 及E15 RNA。突变病毒RNA 侵染烟草(Nicotiana tabacum )后表现不同特性。V9 和E15 侵染XanthiNN烟草后同野生型TMV一样产生枯斑。但是,当它们侵染Xanthinn 烟草时,V9 产生同侵染XanthiNN 烟草相同的枯斑,而E15的特性同TMV-U1几乎完全相同,能对Xanthinn 烟草进行系统侵染并在叶片中聚集大量的带有外源片段的外壳蛋白,而且病毒的结构极其稳定。V9 和E15 特性的差异可能是由于外源片段在外壳蛋白中存在位置的不同影响了外壳蛋白的结构所致 相似文献
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The primary humoral responses of mice to the linear random terpolymerl-Glu56-l-Lys35-l-Phe9 (GLø) were studied, utilizing the Farr antigen-binding technique and a new hemagglutination assay. This new hemagglutinin assay was easier and more convenient than the conventional Farr method, and was more sensitive in detecting early IgM responses. Following primary immunization, the majority of antibodies produced by responder strains were 2-ME-sensitive. These 2-ME-sensitive antibodies chromatographed at the same relative position as IgM on a Sepharose 6B column. On the other hand, no antibodies of either the IgM or IgG class could be detected in nonresponder strains. These data are consistent with the hypothesis that two complementingIr genes are required for the primary IgM response to GLø, in contrast to findings previously reported for (T,G)-A — L, anotherH-2-linked, complementing,Ir gene system. The implications of these differences are discussed. 相似文献
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Tao Guo Ke Chen Nai‐Qian Dong Wang‐Wei Ye Jun‐Xiang Shan Hong‐Xuan Lin 《植物学报(英文版)》2020,62(5):581-600
Auxin is a crucial phytohormone, controlling multiple aspects of plant growth and responses to the changing environment. However, the role of local auxin biosynthesis in specific developmental programs remains unknown in crops. This study characterized the rice tillering and small grain 1 (tsg1) mutant, which has more tillers but a smaller panicle and grain size resulting from a reduction in endogenous auxin. TSG1 encodes a tryptophan aminotransferase that is allelic to the FISH BONE (FIB) gene. The tsg1 mutant showed hypersensitivity to indole‐3‐acetic acid and the competitive inhibitor of aminotransferase, L‐kynurenine. TSG1 knockout resulted in an increased tiller number but reduction in grain number and size, and decrease in height. Meanwhile, deletion of the TSG1 homologs OsTAR1, OsTARL1, and OsTARL2 caused no obvious changes, although the phenotype of the TSG1/OsTAR1 double mutant was intensified and infertile, suggesting gene redundancy in the rice tryptophan aminotransferase family. Interestingly, TSG1 and OsTAR1, but not OsTARL1 and OsTARL2, displayed marked aminotransferase activity. Meanwhile, subcellular localization was identified as the endoplasmic reticulum, while phylogenetic analysis revealed functional divergence of TSG1 and OsTAR1 from OsTARL1 and OsTARL2. These findings suggest that TSG1 dominates the tryptophan aminotransferase family, playing a prominent role in local auxin biosynthesis in rice. 相似文献
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Ying Wang Li‐Ming Zhao Feng‐Jie Fang Ji‐Cheng Liao Nai‐Fa Liu 《Biological journal of the Linnean Society. Linnean Society of London》2013,110(2):362-383
The phylogeographical patterns and demographic history of mitochondrial DNA (cytochrome b, N = 327; D‐loop, N = 252) and nuclear DNA (IRBP gene, N = 235) haplotypes were studied for the Meriones meridianus complex in northern China, a desert‐dwelling gerbil species complex. The phylogenetic analyses, which were performed on the separate and combined (mitochondrial + nuclear) datasets, revealed two divergent clades (Clade A and Clade B) corresponding to distinct geographical regions. Clade A contained the haplotypes found mostly in individuals from the Tianshan Mountains area. Clade B contained haplotypes from populations located in other deserts in northern China. The divergence times indicated that the history of the M. meridianus complex was influenced by the uplift of the Tianshan Mountains and climate‐induced habitat fluctuations. In the Pleistocene, the expansion of forests and grasslands during interglacial period led to the isolation of the M. meridianus complex, which preferred to inhabit deserts. Hence, long geological isolation and the M. meridianus complex adaptation to local ecological conditions led to its genetic divergence. Clade A had long‐lasting demographic stability, most likely because the populations of this clade remained in a stable desert environment for a long time. However, the extension of other deserts and disappearance of palaeolakes during the last glacial period resulted in demographic expansion of Clade B. Furthermore, our genetic data indicated that two subspecies may exist within the M. meridianus complex. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 362–383. 相似文献
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由于肥胖及肥胖相关疾病在全球范围内的广泛流行,明确脂肪组织如何生长非常重要。脂肪组织主要由脂肪细胞分化、脂肪细胞肥大以及脂解作用共同调节。脂肪细胞分化是由多能干细胞或前脂肪细胞分化形成脂肪细胞的一个复杂而又程序化的过程。脂肪细胞的分化过程被分为四个阶段,生长抑制阶段,克隆扩增阶段,早期分化阶段和分化为成熟脂肪细胞表型的终末阶段。来自国内外多个研究的大量数据表明,活性氧(Reactive oxygen species, ROS)可以显著调节脂肪分化的过程进而影响肥胖及相关疾病的发生发展。作为一类重要的高活性分子,ROS在细胞内具有多种来源,主要包括线粒体、NADPH氧化酶、黄嘌呤氧化还原酶、黄嘌呤氧化酶、一氧化氮合酶等。本文回顾近年来的一些文献,对ROS及其生成系统在脂肪细胞分化中的作用进行综述,以期从氧化还原调节的角度明确脂肪细胞分化以及肥胖形成的机制,为肥胖及相关疾病的治疗提供新思路。 相似文献
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