Phylogenetic Analysis of the Small Subunit Ribosomal RNA of Marteilia.refringens Validates the Existence of Phylum Paramyxea (Desportes and Perkins, 1990)¹

Abstract

Marteilia refringens is recognized as one of the most significant pathogens of bivalve molluscs. The nucleotide sequence of the small subunit ribosomal RNA gene of Marteilia refringens is used to elucidate the phylogenetic position of the phylum Paramyxea. Genomic DNA was extracted from sporangia of Marteilia, purified from infected blue mussels, Mytilus edulis, and flat oysters, Ostrea edulis. The sequences obtained from Marteilia species purified from both oysters and mussels were identical. The sequence identity was confirmed by in situ hybridization using a DNA probe targeted to a variable region of the ribosomal DNA. The small subunit ribosomal RNA gene sequence of M. refringens is very different from all known sequences of eukaryotic organisms, including those of myxosporeans and haplosporeans. Therefore, the phylum Paramyxea should continue to be recognized as an independent eukaryotic phylum.

Conservation in the first internal transcribed spacer region (ITS1) in Hematodinium species infecting crustacean hosts found in the UK and Newfoundland

“…Examples include the phylogenetic position of Marteilia refringens (Berthe et al 2000), Pfiesteria shumwayae (Litaker et al 2005), and the phylogenetic synonymization of Perkinsus chesapeaki and P. andrewsi (Burreson et al 2005). Ribosomal DNA sequence variation has previously been used to discriminate between toxic and non-toxic strains of Alexandrium tamarense and Pseudonitzschia spp.…”

Prevalence and infection intensity of the ovarian parasite Marteilioides chungmuensis during an annual reproductive cycle of the oyster Crassostrea gigas

“…Protozoan parasites in the phylum Paramyxea have been extensively studied in areas in which oysters and mussels are commercially raised (Becker & Pauley 1968, Wolf 1977, Figueras & Montes 1988, Villalba et al 1993, Fuentes et al 1995, Renault et al 1995, Camacho et al 1997, Berthe et al 2000, Hine & Thorne 2000. The presence of the ovarian parasite Marteilioides chungmuensis (Comps et al 1986) has been reported from oyster culture grounds in Korea (Chun 1970(Chun , 1972(Chun , 1979 and in Japan (Imai et al 1968, Matsusato & Masumura 1981.…”

Fish and Shellfish Diseases Caused by Marine Protists

“…All paramyxids are parasitic organisms of marine invertebrates. Although a relationship with haplosporidian species was suggested, any phylogenetic relationships with described species have been not confi rmed yet (Berthe et al 2000 ;Reece et al 2004 ), leaving the phylogenetic position of paramyxids under controversy.…”