Collaborative Research: Genomic Evolution in the Endosymbiotic Bacteria (Buchnera) of Aphids

非技术性摘要合作研究：内共生细菌(Buchnera)的基因组进化亚利桑那大学保罗·鲍曼亚利桑那大学保罗·鲍曼，加州大学戴维斯分校南希·A·莫兰，许多无脊椎动物含有特殊的细胞内细菌，这些细菌通过卵从母亲传递给后代，并在宿主谱系中存活数百万年。通常情况下，动物宿主和细菌无法分开生活，这种情况减缓了共生细菌的基因特征。目前的项目扩展了之前昆虫生物学家和细菌学家之间的合作，该合作利用现代分子方法来表征蚜虫共生体中的单个基因。这些细菌经历了基因改造，提高了它们为宿主提供生长和繁殖所需的氨基酸的能力。这项新的研究旨在解决共生体在整体基因组特征上与相关的非共生细菌有何不同的问题。将使用新发展的分子方法来分析蚜虫共生体的基因组结构的动态，这些方法用于确定大的染色体片段的大小和确定来自几个已知亲缘关系的寄主的共生体中特定基因的染色体位置。此外，还将确定具有已知分化日期的共生体对的特定基因的进化速度。这些结果将与遗传数据库中密切相关的非共生细菌的相应信息进行比较。蚜虫的共生体具有一些独特的遗传特征，这些特征似乎代表了细胞内细菌的一般综合征，包括农业害虫的有益共生体和感染人类、其他动植物的病原菌。这些特征包括基因数量减少和基因组大小减少，随着时间的推移遗传变化的速度更快，以及DNA分子的偏向组成。因此，拟议的调查将增加对一种遗传综合征的了解，这种综合征包括各种在农业和医学上具有重要意义的细菌。更多地了解这些生物的基本生物学知识可能有助于找到控制农业害虫和/或病原体的新方法。

Nontechnical AbstractCollaborative Research: Genomic Evolution in the Endosymbiotic Bacteria(Buchnera) of AphidsNancy A. Moran, University of ArizonaPaul Baumann, University of California-DavisMany invertebrates contain specialized intracellular bacteria that are transmitted from mother to offspring in eggs and that persist in host lineages for millions of years. Typically, animal hosts and bacteria are unable to live apart, a situation that has slowed genetic characterization of symbiotic bacteria. The current project extends a previous collaboration, between an insect biologist and a bacteriologist, which has exploited modern molecular methods to characterize individual genes in symbionts of aphids. These bacteria have undergone genetic modifications that improve their ability to provide hosts with amino acids that are required for growth and reproduction. The new research is designed to address the question of how symbionts differ from related nonsymbiotic bacteria in overall genome characteristics. The dynamics of genome structure in aphid symbionts will be analyzed using newly developed molecular methods for determining sizes of large chromosomal fragments and for determining chromosomal locations of specific genes in symbionts from several aphid hosts of known relationships. In addition, rates of evolution of specific genes will be determined for pairs of symbionts with known dates of divergence. These results will be compared to corresponding information, from genetic databases, for closely related nonsymbiotic bacteria.The symbionts of aphids possess some distinctive genetic traits that appear to represent a general syndrome in intracellular bacteria, including both beneficial symbionts of agricultural pests and pathogenic bacteria infecting humans, other animals, and plants. These characteristics include a reduced number of genes and reduced genome size, faster rates of genetic change over time, and biased composition of DNA molecules. Thus, the proposed investigations will increase understanding of a genetic syndrome that encompasses a variety of agriculturally and medically important bacteria. The additional knowledge of the basic biology of these organisms could contribute to new methods of controlling both agricultural pests and/or agents of disease.