Protein evolution. On the ancestry of barrels

Most proteins consist of several domains linked together in a single polypeptide chain, and many of these proteins have evolved by gene duplication and fusion. Miles and Davies discuss the study by Lang et al., who show that this type of protein evolution may also occur in b/a barrel proteins, a common single-domain protein fold. Other single domain proteins may have arisen from similar evolutionary mechanisms.     

鹅细小病毒辽宁株主要结构蛋白基因的克隆及遗传进化分析

根据GenBank登陆的鹅细小病毒B株全基因组的核苷酸序列.设计合成一对引物.用PCR方法对GPV LN-1/06株的主要结构蛋白基因进行克隆,并对克隆的片段进行序列测定,用生物信息学软件进行序列分析.结果表明:所扩增的GPV LN-1/06株的基因长度为1605bp,包括VP3完整的开放阅读框,共编码534个氨基酸.与登录的20株国内和国外的GPV的VP3基因序列进行同源性分析表明,GPV LN-1/06株与其他20株VP3基因的核苷酸同源性较高,从93%至99%,说明GPV的VP3基因较为保守.系统进化树分析表明GPV-LN01/06病毒株与HG5/82为一组,具有较近的亲缘关系.本试验首次获得辽宁地区鹅细小病毒流行株的主要结构蛋白基因(VP3)的核苷酸序列,为研究国内外GPV的遗传演化规律提供参考资料.     

Mitochondrial evolution

The serial endosymbiosis theory is a favored model for explaining the origin of mitochondria, a defining event in the evolution of eukaryotic cells. As usually described, this theory posits that mitochondria are the direct descendants of a bacterial endosymbiont that became established at an early stage in a nucleus-containing (but amitochondriate) host cell. Gene sequence data strongly support a monophyletic origin of the mitochondrion from a eubacterial ancestor shared with a subgroup of the alpha-Proteobacteria. However, recent studies of unicellular eukaryotes (protists), some of them little known, have provided insights that challenge the traditional serial endosymbiosis-based view of how the eukaryotic cell and its mitochondrion came to be. These data indicate that the mitochondrion arose in a common ancestor of all extant eukaryotes and raise the possibility that this organelle originated at essentially the same time as the nuclear component of the eukaryotic cell rather than in a separate, subsequent event.     

全自动凯氏定氮仪测定蛋白饮料中蛋白质的不确定度分析

[目的]减少试验过程中带来的误差,确保蛋白质含量的数据准确性。[方法]采用GB 5009.5—2016第一法,凯氏定氮法测定蛋白饮料中蛋白质含量,其测量不确定度来源于样品称量、消化、蒸馏及滴定等过程。通过对各个不确定度分量的计算合成,找出影响测量不确定度的因素,并对各个不确定度分量进行评估,最终分析出样品核桃花生奶中蛋白质的标准不确定度及扩展不确定度,并描述影响核桃花生奶蛋白质测定结果各分量对其不确定度的相对贡献。[结果]最终通过合成和扩展得出了核桃花生奶中蛋白质含量测定的扩展不确定度为(1.30±0.03)%。[结论]不确定度主要由全自动凯氏定氮仪的仪器滴定体积的不确定度引入,说明仪器的先进性能够有效减少试验过程中的误差。