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The origin of the dinoflagellate plastid
Author(s) -
Bachvaroff T. R.,
Concepcion G. T.,
Rogers C. R.,
Herman E. M.,
Delwiche C. F.
Publication year - 2003
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.2003.03906001_5.x
Subject(s) - peridinin , plastid , biology , minicircle , dinoflagellate , endosymbiosis , phylogenetic tree , chloroplast , evolutionary biology , genome , phylogenetics , eukaryote , nuclear gene , gene , horizontal gene transfer , genetics , botany , algae , fucoxanthin
Dinoflagellates are griffins, that is the merger of two eukaryotes: a heterotrophic host, the dinoflagellate, and a photosynthetic eukaryote. Our work has been focussed on the endosymbiont's identity and the massive gene transfer implied by secondary endosymbiosis. Dinoflagellates have many different types of chloroplasts, but the majority of photosynthetic dinoflagellates are pigmented with the carotenoid peridinin and chlorophyll c. The chloroplast genome of these organisms is cryptic. Genes that have been attributed to the chloroplast are encoded on minicircles that contain one or two genes. Phylogenetic analysis using these genes suggests that the peridinin chloroplast was derived from haptophytes. Since these minicircle genes have an extreme rate of change phylogenetic methods may produce misleading results. Statistical tests were used to test the quality of phylogenetic methods given these data, particularly the maximum likelihood model. To find plastid associated genes with more reasonable evolutionary rates an expressed sequence tag survey was begun. Among these sequences many typically plastid encoded genes were found including six genes that are exclusively plastid encoded in other eukaryotes. These data suggest massive chloroplast to nucleus gene transfer in dinoflagellates, and fits well with the small complement of minicircle genes. Phylogenetic analyses using these typically plastid encoded genes was also performed. It is now possible to directly test hypotheses of plastid origin within dinoflagellates and the chlorophyll c containing algae.