Genome history in the symbiotic hybrid Euglena gracilis.
Euglena gracilis has a chimeric gene collection in which some genes were inherited from its heterotrophic host and others were acquired from a photoautotrophic endosymbiont during secondary endosymbiosis. The evolutionary reconstruction of such a hybrid genome poses a challenge for standard phylogenetic tools that produce bifurcating trees because genome evolution by endosymbiotic gene transfer is a non tree-like process. We sequenced 2770 ESTs from E. gracilis, of which 841 have homologues in a sample of other eukaryotes. Most of these homologues are found in all of the eukaryotes in our sample, but 117 of them are specific to photoautotrophic eukaryotes. A phylogenetic tree fails to account for this observation but the distribution of homologues and a phylogenetic network clearly show the common origin of E. gracilis from both kinetoplastid and photoautotrophic ancestors.
Ahmadinejad
Nahal
N
Institut für Botanik III, Heinrich-Heine Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.
Dagan
Tal
T
Martin
William
W
D000818:Animals; D002678:Chimera / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D005056:Euglena gracilis / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D016678:Genome; D006801:Humans; D010802:Phylogeny; D013559:Symbiosis / Q000235:genetics*
D018076:DNA, Complementary