The Classification of Prokaryotes

伊利诺伊大学的Carl Woese博士正在继续他在细菌进化、系统发育和分类方面的开创性研究，他使用核糖体RNA的核苷酸序列数据来量化细菌之间的遗传差异。通过比较不同生物的核糖体RNA序列，可以构建一个具有亲和性的分支模式；物种之间的核苷酸差异很少表明进化关系密切（共享来自接近的共同祖先的相似基因组），而较大的基因差异表明谱系之间更古老的分歧。沃斯博士的研究重点是梭状芽胞杆菌和黄杆菌，以及其他传统上被称为革兰氏阳性类型的微生物群。这种细菌系统发育分析的一个额外好处是使用核糖体序列来设计物种诊断的寡核苷酸探针。这些探针已成功地应用于医学和生态学研究中，以鉴定在实验室中难以或不可能培养的细菌。此外，通过比较核苷酸序列揭示的系统发育关系为解释和研究微生物生理、生物化学和生态学的其他方面提供了一个进化框架。

Dr. Carl Woese of the University of Illinois is continuing his pioneering studies on the evolution, phylogeny, and classification of bacteria, by using nucleotide sequence data from ribosomal RNA to quantify genetic differences between bacteria. By comparing the sequence of ribosomal RNA from a variety of organisms, a branching pattern of genealogical affinity can be constructed; few nucleotide differences between species indicate close evolutionary relationship (the sharing of similar genomes from a close common ancestor) whereas greater gene differences indicate more ancient divergence between lineages. Dr. Woese is concentrating on clostridial and flavobacterial organisms, and other groups traditionally called Gram-positive types. An added dividend to this phylogenetic analysis of bacteria is the use of ribosomal sequences to design species-diagnostic oligonucleotide probes. These probes have been successfully employed in both medical and ecological studies to identify bacteria that have otherwise proved difficult or impossible to culture in the laboratory. In addition, the phylogenetic relationships revealed through comparative nucleotide sequences provide an evolutionary framework for interpreting and studying other aspects of the physiology, biochemistry, and ecology of microbial organisms.