Origin of the Eukaryote Nucleus and Metabolic Innovations

真核生物细胞核的起源和代谢创新

• 批准号: 9119801
• 负责人: James Lake
• 金额: $ 66.5万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-02-15 至 1998-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9119801&HistoricalAwards=false
• 关键词: Origin; Eukaryote; Nucleus; Metabolic; Innovations

The general objectives of this proposal are to relate the phylogenetic trees derived from molecular sequences from extant taxa to the geological, paleontological, and biochemical records; to changes in the atmosphere and biota; and to the origin of present day life. Three specific objectives are: (1) to test theories for the origin of the eukaryotic nucleus and to seek to identify its prokaryotic sister taxon; (2) to relate phylogenetic trees to the origin of metabolic innovations, such as the beginnings of photosynthesis, oxygen production, methanogenesis, and sulfur reduction and oxidation; and (3) to relate the phylogenetic tree to the fossil and geological records, through correlation with such factors as the time of appearance of oxygen in the atmosphere, the isotopic abundances of sulfur and carbon, the appearance of prokaryotic fossils, and with endosymbiotic events. Specific goals are to sequence three molecules (EF-Tu, Ef-G, and the trp B gene) from a diverse group of twelve taxa that exhibit metabolic innovations that are essential to understanding early events in life. Phylogenetic trees will be inferred, paying particular attention to artifacts of sequence alignment deriving unrooted phylogenetic trees from molecular sequences. The EF-Tu and trp B genes are particularly useful because they have low rates of nucleotide substitution and because EF-Tu and EF-G arose through an early gene duplication so that the tree can be rooted using these paralogous genes. Taxa have been chosen to assist in identifying the sister taxon to the eukaryotic nucleus, and to be useful in asking what were the earliest types of metabolisms.

该提案的总体目标是将源自现有类群分子序列的系统发育树与地质、古生物学和生化记录联系起来； 大气和生物群的变化；以及现代生活的起源。 三个具体目标是：（1）检验真核细胞核起源的理论并寻求鉴定其原核姐妹分类单元； （2）将系统发育树与代谢创新的起源联系起来，例如光合作用、氧气产生、产甲烷以及硫还原和氧化的开始； （3）通过与大气中氧气出现的时间、硫和碳的同位素丰度、原核化石的出现以及内共生事件等因素的相关性，将系统发育树与化石和地质记录联系起来。 具体目标是对来自十二个不同类群的三个分子（EF-Tu、Ef-G 和 trp B 基因）进行测序，这些分子表现出对于理解生命早期事件至关重要的代谢创新。 将推断系统发育树，特别注意从分子序列导出无根系统发育树的序列比对伪影。 EF-Tu 和 trp B 基因特别有用，因为它们的核苷酸取代率较低，而且 EF-Tu 和 EF-G 是通过早期基因复制产生的，因此可以使用这些旁系同源基因使树生根。 选择分类单元是为了帮助识别真核细胞核的姊妹分类单元，并有助于探究最早的新陈代谢类型。