Isolation, physical map and gene map of mitochondrial DNA from the cryptomonad Pyrenomonas salina

Abstract

Mitochondrial DNA (mtDNA) from the cryptomonad Pyrenomonas salina was isolated by CsCl-buoyant density centrifugation of whole-cell DNA in the presence of Hoechst dye 33258. mtDNA consists of circular molecules about 47 kb in size as estimated from restriction enzyme analysis. A physical map for six restriction enzymes (Bam HI, Bge I, Eco RI, Pst I, Sac I and Sal I) has been constructed. Genes coding for the small subunit of rRNA, cytochrome oxidase subunits I and II, and apocytochrome b were localized on this map using Southern blot hybridization with heterologous gene probes from Oenothera. Genes for 5S rRNA and NADH dehydrogenase subunit 5 are absent from P. salina mtDNA. The mitochondrial genome, being the first analysed to this extent in chromophytic algae, should be valuable for taxonomic and phylogenetic studies.

UTILITY OF THE MITOCHONDRIAL nad4L GENE FOR ALGAL AND PROTISTAN PHYLOGENETIC ANALYSIS1

“…T h e number of studied algal mitochondrial genomes is extremely minimal. However, reported genome sizes for chlorophytes (20-150 kb) (Gray and Boer 1988, Misonou et al 1989, Moore and Coleman 1989, Denovan-Wright and Lee 1992, Wolff and Kiick 1993, chlorarachniophytes (36 kb) (Gilson et al 1995), chrysophytes (50 kb) (Aldrich and Cattolico 198 l), cryptophytes (35-70 kb) (Chesnick et al 1991, Maerz andSitte 1991), and rhodophytes (27-350 kb) Cattolico 1987, Boyen et al 1994) suggest that small mitochondrial genomes may be universal among algal representatives. Given the size homogeneity of mtDNA populations seen in all algae examined to date, algal mtDNA most likely retains a different (i.e.…”