tailieunhanh - Báo cáo y học: "The origin and early evolution of eukaryotes in the light of phylogenomics"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: The origin and early evolution of eukaryotes in the light of phylogenomics. | Koonin Genome Biology 2010 11 209 http 2010 11 5 209 w Genome Biology REVIEW L_ The origin and early evolution of eukaryotes in the light of phylogenomies Eugene V Koonin Abstract Phylogenomics of eukaryote supergroups suggest a highly complex last common ancestor of eukaryotes and a key role of mitochondrial endosymbiosis in the origin of eukaryotes. Eukaryotes The origin of eukaryotes is a huge enigma and a major challenge for evolutionary biology 1-3 . There is a sharp divide in the organizational complexity of the cell between eukaryotes which have complex intracellular compartmentalization and even the most sophisticated prokaryotes archaea and bacteria which do not 4-6 . A typical eukaryotic cell is about 1 000-fold bigger by volume than a typical bacterium or archaeon and functions under different physical principles free diffusion has little role in eukaryotic cells but is crucial in prokaryotes 7 8 . The compartmentalization of eukaryotic cells is supported by an elaborate endomembrane system and by the actin-tubulin-based cytoskeleton 9 10 . There are no direct counterparts of these organelles in archaea or bacteria. The other hallmark of the eukaryotic cell is the presence of mitochondria which have a central role in energy transformation and perform many additional roles in eukaryotic cells such as in signaling and cell death. The conservation of the major features of cellular organization and the existence of a large set of genes that are conserved across eukaryotes leave no doubt that all extant eukaryotic forms evolved from a last eukaryote common ancestor LECA see below . All eukaryotes that have been studied in sufficient detail possess either mitochondria or organelles derived from mitochondria 11-13 so it is thought that LECA already possessed Correspondence koonin@ National Center for Biotechnology Information National Institutes of Health Bethesda MD 20894 USA 2 BioMed Central 2010 BioMed Central Ltd .