Cyanidioschyzon merolae Genome Project

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Technical improvements

Improvement of culture conditions and evidence for nuclear transformation by homologous recombination in a red alga, Cyanidioschyzon merolae 10D.
Minoda A, Sakagami R, Yagisawa F, Kuroiwa T, Tanaka K.
Although the nuclear genome sequence of Cyanidioschyzon merolae 10D, a unicellular red alga, was recently determined, DNA transformation technology that is important as a model plant system has never been available thus far. In this study, improved culture conditions resulted in a faster growth rate of C. merolae in liquid medium (doubling time = 9.2 h), and colony formation on gellan gum plates. Using these conditions, spontaneous mutants (5-fluoroortic acid resistant) deficient in the UMP synthase gene were isolated. The lesions were then restored by introducing the wild-type UMP synthase gene into the cells suggesting DNA transformation by homologous recombination.

Isolation of cycloheximide-resistant mutants of Cyanidioschyzon merolae.
Yagisawa F, Nishida K, Okano Y, Minoda A, Tanaka K, Kuroiwa T.
Cytologia 2004 Mar;69(1):97-100.
Cyanidioschyzon merolae is a unicellular red alga that lives in acidic hot springs. The genome sequence of C. merolae has been completely read, but a lack of transformation systems still limits its application in genetics. To choose an appropriate drug for use in selectable media, we examined the effects of seven antibiotics on the growth of C. merolae. Only cycloheximide, an inhibitor of protein sysnthesis, effectively inhibited the growth. We noticed that there was a population that could survive in the presence of cycloheximide and succeeded in isolating six cycloheximide-resistant clones. All these clones have the same single mutation in the ribosomal protein L29 gene that encodes a ribosomal protein.