SPECIES VARIATION WITHIN THE INTERNAL TRANSCRIBED SPACER (ITS) REGIONOF GYRODACTYLUS (MONOGENEA, GYRODACTYLIDAE) RIBOSOMAL-RNA GENES

The ribosomal internal transcribed spacer (ITS) region from individual Gyrodactylus specimens was amplified by polymerase chain reaction (PC R). The reaction amplified the entire ITS1-5.8S-ITS2 region of the rib osomal RNA ene cluster using primers that hybridize to the 3' terminus of the small subunit and the 5' terminus of the large subunit ribosom al RNA genes. The PCR products from Gyrodactylus safaris and Gyrodacty lus thymalli were cloned and sequenced. The Gyrodactylus 5.8S gene was identified following comparative alignment of the G. salaris sequence and a Schistosoma 5.8S gene sequence. The ITS regions from G. safaris , G. thymalli, Gyrodactylus derjavini, and Gyrodactylus truttae were c ompared by restriction enzyme analysis and interspecific restriction f ragment length polymorphisms were found. Gyrodactylus safaris and G. t hymalli restriction fragment sizes were confirmed from sequence data. ITS amplification followed by Sau3AI digestion enables rapid and clear differentiation of G. safaris, G. derjavini, and G. truttae.