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Mol. Biol. Evol. 19(4):422431. 2002 2002 by the Society for Molecular Biology and Evolution. ISSN: 0737-4038
 

Summary: 422
Mol. Biol. Evol. 19(4):422431. 2002
2002 by the Society for Molecular Biology and Evolution. ISSN: 0737-4038
The Chaperonin Genes of Jakobid and Jakobid-Like Flagellates:
Implications for Eukaryotic Evolution
John M. Archibald,*1 Charles J. O'Kelly, and W. Ford Doolittle*
*Department of Biochemistry and Molecular Biology, Dalhousie University; and Bigelow Laboratory for Ocean Sciences
The jakobids are free-living mitochondriate protists that share ultrastructural features with certain amitochondriate
groups and possess the most bacterial-like mitochondrial genomes described thus far. Jakobids belong to a diverse
group of mitochondriate and amitochondriate eukaryotes, the excavate taxa. The relationships among the various
excavate taxa and their relationships to other putative deep-branching protist groups are largely unknown. With the
hope of clarifying these issues, we have isolated the cytosolic chaperonin CCTalpha gene from the jakobid Recli-
nomonas americana (strains 50394 and 50283), the jakobid-like malawimonad Malawimonas jakobiformis, two
heteroloboseans (Acrasis rosea and Naegleria gruberi), a euglenozoan (Trypanosoma brucei), and a parabasalid
(Monocercomonas sp.). We also amplified the CCTdelta gene from M. jakobiformis. The Reclinomonas and Ma-
lawimonas sequences presented here are among the first nuclear protein-coding genes to be described from these
organisms. Unlike other putative early diverging protist lineages, a high density of spliceosomal introns was found
in the jakobid and malawimonad CCTs--similar to that observed in vertebrate protein-coding genes. An analysis
of intron positions in CCT genes from protists, plants, animals, and fungi suggests that many of the intron-sparse
or intron-lacking protist lineages may not be primitively so but have lost spliceosomal introns during their evolu-

  

Source: Archibald, John - Department of Biochemistry and Molecular Biology, Dalhousie University

 

Collections: Biology and Medicine