From doering@ncbi.nlm.nih.gov Tue Feb 3 11:01:53 1998 Return-Path: Received: from ray.nlm.nih.gov by frodo.nlm.nih.gov id LAA02088; Tue, 3 Feb 1998 11:01:52 -0500 Received: from ncbi.nlm.nih.gov by ray.nlm.nih.gov id KAA20049; Tue, 3 Feb 1998 10:59:47 -0500 Received: from esprit.nlm.nih.gov (esprit [130.14.25.160]) by ncbi.nlm.nih.gov (8.8.8/8.8.8) with SMTP id KAA04191; Tue, 3 Feb 1998 10:59:47 -0500 (EST) Received: by esprit.nlm.nih.gov id KAA10551; Tue, 3 Feb 1998 10:59:46 -0500 Date: Tue, 3 Feb 1998 10:59:46 -0500 Message-Id: <199802031559.KAA10551@esprit.nlm.nih.gov> From: Hidemi Watanabe To: ncbi-seminar@ncbi.nlm.nih.gov Cc: watanabe@ncbi.nlm.nih.gov Subject: NCBI Seminar (Feb 10, 1998) X-Mailer: VM 6.34 under 20.3 "Vatican City" XEmacs Lucid Mime-Version: 1.0 (generated by tm-edit 7.108) Content-Type: text/plain; charset=US-ASCII Content-Length: 2908 X-IMAPbase: 1000759423 1 Status: O X-Status: X-Keywords: X-UID: 1 CBB Seminar (11:00, February 10, Conference Room, 8th Floor, Bldg 38A) R E C O N S T R U C T I O N O F A N C E S T R A L G E N O M E S WATANABE, Hidemi (NCBI/NLM/NIH) One of the objectives of evolutionary studies is to know about organisms in the past. In molecular evolutionary studies, some states of genes in ancestral organisms are inferred. Since it is difficult or impossible to obtain the fossil record of most ancient organisms, molecular evolutionary approaches are crucial for knowing something about them. However, it is still difficult for us to know about ancestral organisms or species with individual molecular evolutionary studies since organisms are a system of a lot of gene products, which might be more than a simple collection of gene products. In order to get more insights into species evolution with molecular evolutionary studies, we are conducting genome evolutionary studies, that is, inference of states of ancestral genomes or reconstruction of ancestral genomes. In practice, using the complete genome sequence data of eleven prokaryotes, in which three archaeal species are included, the gene compositions and gene order in ancestral genomes are inferred from the results of molecular evolutionary studies. For the inference of gene composition, some orthological analyses including the use of the COG data (Tatusov et al., 1997) were conducted. With the data of orthologous gene pairs identified between different genomes, it is also possible to know the conservation of gene order in the genomes and infer gene clusters in a common ancestral genome. This study is still ongoing, but, so far, about 470 orthologous gene groups have been identified between Archaea and Bacteria (Eubacteria). Among them about eighty genes have been found to form gene clusters, in which gene order is conserved in both archaeal and bacterial genomes. This number corresponds to about 1/6 of the genome of Mycoplasma genitalium. Since these conserved regions are found in both archaeal and bacterial genomes, it is very likely that they were also part of the genome of the common ancestor of Archaea and Bacteria. Moreover, if we accept the root position in the Woesian tree, it is possible to infer that the genome of the last common ancestor of all the modern species (cenancestor) had very similar structures to the gene clusters identified. Based on these results, backtrack characterizations of ancestral species would be possible without fossil record. Several evolutionary tendencies found by looking at the variations in the conserved regions and the evolution of some genes in the conserved regions will be discussed. Acknowledgments: David Lipman, Eugene Koonin and Roman Tatusov WATANABE, Hidemi NCBI/NLM/NIH Bldg 38A, Rm B2N14 Email: watanabe@ncbi.nlm.nih.gov Phone: (301)435-5896 Fax: (301)435-2433