核质杂种小麦Rubisco大亚基的基因结构与功能的关系

NC4号小麦是一高产、抗逆的核质杂种 ,它是由山羊草 (Aegilops squarrosa,♀ )与小麦 (Triticumaestivum, )杂交 ,并多次回交和筛选而获得。测定了 NC4号及其父本的 Rubisco rbc L序列 ,证明 NC4号的 rbc L是由山羊草基因编码。对核质杂种及其亲本 Rubisco的羧化和加氧活性测定表明 ,杂种的羧化 /加氧活性比低于母本山羊草 ,高于父本小麦。rbc L序列测定表明 ,NC4号与父本小麦的 rbc L 有 3个核苷酸的差异 ,即在其氨基酸序列上第 14、86和 95位有 3个残基不同。     

Lateral gene transfer, lineage-specific gene expansion and the evolution of Nucleo Cytoplasmic Large DNA viruses

Nucleo Cytoplasmic Large DNA viruses (NCLDVs) are a diverse group that infects a wide range of eukaryotic hosts (for example, vertebrates, insects, protists,…) and also show a huge range in genome size (between 100 kb and 1.2 Mb). Here I review some recent results that shed light on the origin and genome evolution of these viruses. Current data suggests that NCLDVs could have originated from a simple and ancient viral ancestor with a small subset of 30-35 genes encoding replication and structural proteins. Subsequent lateral gene transfer of both cellular genes and diverse families of Mobile Genetic Elements, followed by massive lineage-specific gene duplications is probably responsible for the huge diversity of genome size and composition found in extant NCLDVs.