GENETIC ANALYSES OF AUTHENTIC AND ALTERNATE FORMS OF CHRYSOCHROMULINA-POLYLEPIS (HAPTOPHYTA)

Two motile cell types (authentic and alternate), differing in their or ganic body scale morphology, were observed in some clonal cultures of Chrysochromulina polylepis Manton et Parke that originated from the 19 88 toxic bloom in Skagerrak and Kattegat. Nucleotide sequences from th e small subunit ribosomal DNA (18S SSU rDNA) and the first internal tr anscribed spacer (ITS1) region from several strains of C. polylepis an d from other Chrysochromulina species were compared to provide further evidence that both cell types are forms of C. polylepis. Strains of b oth cell types isolated from Norway were identical in these genomic re gions but differed from those of a British strain of C. cf. polylepis and other Chrysochromulina species. Similar fragment lengths were also obtained for both cell types from Norway from PCR amplification of th e third intron within a calmodulin gene, but these differed in length from that of the British strain. Our results suggest that both cell ty pes are the same species, increasing the likelihood that the earlier h ypothesis of the two cell types being joined in a sexual haplo-diploid life cycle is valid. Other Chrysochromulina species could display suc h life cycles, further complicating Chrysochromulina taxonomy.