an expanded inventory of conserved meiotic genes provides evidence for sex in trichomonas vaginalis扩大库存守恒的减数分裂基因提供了证据在阴道毛滴虫性.pdfVIP

An Expanded Inventory of Conserved Meiotic Genes Provides Evidence for Sex in Trichomonas vaginalis Shehre-Banoo Malik¤a, Arthur W. Pightling, Lauren M. Stefaniak¤b, Andrew M. Schurko, John M. Logsdon, Jr.* Department of Biology, Roy J. Carver Center for Comparative Genomics, University of Iowa, Iowa City, Iowa, United States of America Abstract Meiosis is a defining feature of eukaryotes but its phylogenetic distribution has not been broadly determined, especially among eukaryotic microorganisms (i.e. protists)—which represent the majority of eukaryotic ‘supergroups’. We surveyed genomes of animals, fungi, plants and protists for meiotic genes, focusing on the evolutionarily divergent parasitic protist Trichomonas vaginalis. We identified homologs of 29 components of the meiotic recombination machinery, as well as the synaptonemal and meiotic sister chromatid cohesion complexes. T. vaginalis has orthologs of 27 of 29 meiotic genes, including eight of nine genes that encode meiosis-specific proteins in model organisms. Although meiosis has not been observed in T. vaginalis, our findings suggest it is either currently sexual or a recent asexual, consistent with observed, albeit unusual, sexual cycles in their distant parabasalid relatives, the hypermastigotes. T. vaginalis may use meiotic gene homologs to mediate homologous recombination and genetic exchange. Overall, this expanded inventory of meiotic genes forms a useful ‘‘meiosis detection toolkit’’. Our analyses indicate that these meiotic genes arose, or were already present, early in eukaryotic evolution; thus, the eukaryotic cenancestor contained most or all components of this set and was likely capable of performing meiotic recombination using near-universal meiotic machinery. Citation: Malik S-B, Pightling AW, Stefaniak LM, Schurko AM, Logsdon JM Jr (2008) An Expanded Inven