Change of address
4 months ago in Variety of Life
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.Here are my impressions of publishing in PLoS ONE (so far)...
"Green Porno is a series of very short films conceived, written, directed by and featuring Isabella Rossellini about the sex life of bugs, insects and various creatures. The films are a comical, but insightful study of the curious ways certain bugs “make love”.My favorite is one of two non-arthropod shorts: the Snail (pictured above).
Each film is executed in a very simple childlike manner. They are a playful mixture of real world and cartoon. Each episode begins with Isabella speaking to the camera “If I were a…(firefly, spider, dragonfly etc.). She then transforms into the male of the species explaining in a simple yet direct dialogue the actual act of species specific fornication. The costumes, colorful sets and backdrops as well as the female insects (all simple paper cut-outs and sculptures) contribute to the playfulness of the films. The contrast of this “naïf” expression and filthy sex practices adds to the comicality of Green Porno. This child-like manner allows us to describe things that could possibly come across as offensive to some."
Abstract
Spo11 is a meiotic protein of fundamental importance as it is a conserved meiosis-specific transesterase required for meiotic recombination initiation in fungi, animals and plants. Spo11 is homologous to the archaebacterial topoisomerase VIA (Top6A) gene, and its homologs are broadly distributed among eukaryotes, with some eukaryotes having more than one homolog. However, the evolutionary relationships among these genes are unclear, with some debate as to whether eukaryotic homologs originated by lateral gene transfer. We have identified and characterized protist Spo11 homologs by degenerate PCR and sequencing and by analyses of sequences from public databases. Our phylogenetic analyses show that Spo11 homologs evolved by two ancient eukaryotic gene duplication events prior to the last common ancestor of extant eukaryotes, resulting in three eukaryotic paralogs: Spo11-1, Spo11-2 and Spo11-3. Spo11-1 orthologs encode meiosis-specific proteins and are distributed broadly among eukaryotic lineages, though Spo11-1 is absent from some protists. This absence coincides with the presence of Spo11-2 orthologs, which are meiosis-specific in Arabidopsis and are found in plants, red algae and some protists, but absent in animals and fungi. Spo11-3 encodes a Top6A subunit that interacts with topoisomerase VIB (Top6B) subunits, which together play a role in vegetative growth in Arabidopsis. We identified Spo11-3 (Top6A) and Top6B homologs in plants, red algae, and a few protists, establishing a broader distribution of these genes among eukaryotes, indicating their likely vertical descent followed by lineage-specific loss.
"I'm glad that John Logsdon has been working on this, rather than me."Thanks, Rosie!
"Birds do it. Bees do it. Humans do it. In fact every animal on this earth does it. But do they all do it the same way? Mating habits in the animal kingdom range from the sublime to ridiculous, but each animal, in their own unique way, accomplishes the same goal.More weird and wonderful sex in the blogosphere. Gotta love it!
Welcome to the Secret Sex Lives of Animals, a weekly column written by an evolutionary biologist on the bizarre, wonderful, colourful and sometimes shocking world of animal mating habits. The Secret Sex Lives of Animals is published each Monday at and short updates appear throughout the week."