Evolution of Homopterae and Their intracellular Symblonts

1.这项国际科学研究计划使我们能够详细研究社会蚜虫的生态学。对美国科罗拉多州和亚利桑那州的红腹小蠹的生活史进行了调查。在亚利桑那州红腹小蠹的生活史与迁徙无关，而在科罗拉多州红腹小蠹的生活史分为迁徙和非迁徙两个阶段。对虫瘿中个体的分析表明，非迁移性生活史是由迁移性生活史通过虫瘿中的寄生虫和寄生虫的寄生化而次级进化而来的，支持Aoki和Kurosu（1986）的GP假说.除少数特定类群外，所有种类的蚜虫细菌细胞中都含有原核共生体。以往的研究表明，蚜虫不像许多其他昆虫那样将氮废物转化为尿酸，而是从废物中产生Gln和Asn。氨基酸被共生体代谢，为宿主生产必需氨基酸。本研究 ...更多信息 证明了稻飞虱利用其酵母样共生体以不同的方式分解有机硝基化合物。稻飞虱从排泄物中产生尿酸并将其储存在组织中，共生体代谢尿酸产生对宿主有用的含氮化合物。蚜虫共生体，与大肠杆菌密切相关，属于变形菌门的γ 3亚门。它选择性地合成大量的共生素，共生素是一种与大肠杆菌GroEL同源的应激蛋白，其功能是分子伴侣。本研究比较了3种蚜虫共生蛋白和GroEL共生蛋白的核苷酸序列，结果表明，在3种蚜虫共生蛋白中，有一个特定的位置极易发生氨基酸替换，通过这种替换，GroEL共生蛋白的同源物在具有分子伴侣活性的基础上，还具有磷酸转移酶的独特功能。这可能代表了在正选择压力下分子非中性进化的一个罕见例子。少

1. This International Scientific Research Program enabled us to work on the ecology of social aphids in detail. We investigated the life cycle of The cabius populimonilis in Colorada and Arizona, U.S.A.In Arizona their life cycle was not associated with migration while in Colorado the life cycle was divided into two, migratory and non-migratory. Analyzes of the individuals in the gall suggested that non-migratory life cycle has evolved secondarily from the migratory one through viviposition by alatae within the gall and apterization of alatae in support of the GP hypothesis by Aoki and Kurosu (1986).2. Except a few specified groups, all the aphid species harbor prokaryotic symbiont in the bacteriocyte. The previous studies demonstrated that aphid, unlike many other insects, does not convert the nitrogen wastes into uric acid, but produces Gln and Asn from the wastes. The amino acids are metabolized by the symbionts to produce essential amino acids for the host. In the present study, we … More demonstrated that planthopper recycles organic nitrogeous compounds in a different manner exploiting its yeastlike symbiont. Planthopper produces uric acid from the wastes and stores it in the tissue, which symbiont metabolizes to produce nitrogenous compounds usable to the host.3. Aphid symbiont, closely related to E.coli, belongs to the gamma3 subdivision of Proteobacteria. It synthesizes selectively a large amount of symbionin, a stress protein homologous to E.Coli GroEL,which functions as molecular chaperone. In the present study, nucleotide sequences encoding symbionins from three closely interrelated aphids were compared with one another and that for GroEL.It was suggested that in these proteins a particular position is highly susceptible to amino acid substitution, through which symbionins, the GroEL homologs symbionts seemed to have acquired a unique function as phosphotransferase on top of the activity as molecular chaperone. This may represent a rare example of non-neutral evolution of molecule under the positive selection pressure. Less