China Science

The Gyrodactylus fauna of 274 fish taken from ten salmonid farms in Polandwas sampled in 2006. Four fish species were investigated: rainbow trout Oncorhynchus mykiss, browntrout Salmo trutta (morphs fario, lacustris, and trutta), grayling Thymallus thymallus and huchenHucho hucho. No parasites were observed on huchen. No indications of gyrodactylosis were observed,but an unexpected parasite species diversity was found. A molecular species identification bypolymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) of ITS1 + 5.8S +ITS2 was utilized, with addition of morphometric methods. The most frequent parasite was a newrecord in Poland, G. teuchis. It was present in two molecular forms on brown trout and rainbowtrout, which also carried G. derjavinoides and G. truttae. Three molecular forms of G. salaris/G.thymalli were found, the standard type ITS only on grayling. A heterozygous (or heterogenic) G.salaris type described earlier in Denmark was found in seven farms on rainbow trout, and acomplementary homozygous clone which differs from the standard by three nucleotides, in two farms.This homozygous form has not been recorded earlier. The PCR-RFLP results were confirmed bysequencing ITS segment from representative specimens of each type and comparing them with allavailable salmonid-specific Gyrodactylus sequences in GenBank. The Polish fauna with seven differentGyrodactylus clones separated by PCR-RFLP was the most diverse reported in fish farms in anycountry so far.

Rokicka, M　Lumme, J　Zietara, MS
Univ Gdansk, Biol Stn, Lab Comparat Biochem, PL-80680 Gdansk, Poland; OuluUniv, Dept Biol, FI-90014 Oulu, Finland

Monogenea　 Gyrodactylus　 species identification　 PCR-RLFP　 Polish salmonidfarms　 OPISTHAPTORAL HARD PARTS　 SALARIS MALMBERG　 ATLANTIC SALMON　 SEASONAL-VARIATIONS　 DERJAVINIMIKAILOV　 MOLECULAR MARKERS　 HOST-SPECIFICITY　 VON-NORDMANN RNA GENE PLATYHELMINTHES