11th Meeting of the International Society for Evolutionary Protistology (ISEP-11)
8-13 AUG 1996 Cologne, Germany. Invited presentation.
PHYLOGENETIC RELATIONSHIP OF RED, GREEN AND CRYPTOPHYTE ALGAE,
INVESTIGATED BY COMPLETE MITOCHONDRIAL DNA SEQUENCING.
G.Burger*, B.F. Lang, M.W. Gray, R.C. Cedergren,
B. Golding, C. Lemieux, D. Sankoff, M. Turmel.
(Presented by *.)
Organelle Genome Megasequencing Program, Canadian Institute for
Advanced Research, Departement de Biochimie, Universite de
Montreal, Montreal, Quebec H3C 3J7, Canada.
The Organelle Genome Megasequencing Program (OGMP) is systematically
investigating the mitochondrial genomes of protists. Compared to the fungal,
animal and plant kingdoms, protista are the phylogenetically most diverse
eukaryotic group. We have completely sequenced the mitochondrial DNA
(mtDNA) from Prototheca wickerhamii (green alga), Porphyra purpurea (red
alga), Rhodomonas salina (cryptomonad alga), Ochromonas danica
(chrysophyte alga), Cafeteria roenbergensis (bicosoecid zooflagellate),
Acanthamoeba castellanii (rhizopod amoeba) and Tetrahymena pyriformis
(ciliate protozoon). Other genomes are in progress, including Pedinomonas
minor (green alga) and Reclinomonas americana, Malawimonas jakobiformis
and Jakoba libera (jakobid flagellates). The data set from this broad selection
of taxa allows us to compare the diverse patterns of mitochondrial gene
content and genome organization present in protists. We will present unusual
genes (DNA polymerase, ribosomal protein L20) and genome structures
(linear DNA and long repeat regions) that we have found in Ochromonas and
Rhodomonas mtDNA. Phylogenetic reconstructions based on multiple
mitochondrial protein sequences allow to resolve the branching order of early
diverging assemblages. Our results support, with high bootstrap probability,
the idea that red and green algae diverged from a common ancestor that
emerged later in eukaryote evolution than cryptophyte algae.
The OGMP is endorsed by the Canadian Institute for Advanced Research.
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