|
Lokiarchaeota is a proposed phylum of the Archaea. It was introduced in 2015 after the identification of a candidate genome in a metagenomic analysis of a mid-oceanic sediment sample. This suggests the existence of a genus of unicellular life dubbed ''Lokiarchaeum''. The sample was taken near a hydrothermal vent at a site known as Loki's Castle on Gakkel Ridge in the Arctic Ocean. Its significance stems from a phylogenetic analysis that disclosed a monophyletic grouping of the Lokiarchaeota with the eukaryotes, and which revealed several genes with cell membrane-related functions; the presence of such genes support the hypothesis of the archaeal host (or eocyte-like scenarios) for the emergence of the eukaryotes. ==Discovery== Sediments from a gravity core taken in 2010 in the rift valley on the Knipovich ridge in the Arctic Ocean, near the so-called Loki's Castle hydrothermal vent site, were analysed. Specific sediment horizons, previously shown to contain high abundances of novel archaeal lineages were subjected to metagenomic analysis. Due to the low density of cells in the sediment, the resulting genetic sequence does not come from an isolated cell, as would be the case in conventional analysis, but is rather a combination of genetic fragments.〔 The result was a 92% complete, 1.4 fold-redundant composite genome named ''Lokiarchaeum''.〔 The metagenomic analysis determined the presence of an organism's genome in the sample. However, the organism itself has not been cultured.〔 The Lokiarchaeota phylum was proposed based on phylogenetic analyses using a set of highly conserved protein-coding genes.〔 Through a reference to the hydrothermal vent complex from which the first genome sample originated, the name refers to Loki, the Norse shape-shifting god.〔 The Loki of literature has been described as "a staggeringly complex, confusing, and ambivalent figure who has been the catalyst of countless unresolved scholarly controversies", in analogy to the ongoing debates on the origin of eukaryotes. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lokiarchaeota」の詳細全文を読む スポンサード リンク
|