DISCRIMINATION BETWEEN GYRODACTYLUS-SALARIS, G-DERJAVINI AND G-TRUTTAE (PLATYHELMINTHES, MONOGENEA) USING RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISMS AND AN OLIGONUCLEOTIDE PROBE WITHIN THE SMALL-SUBUNIT RIBOSOMAL-RNA GENE

The small subunit ribosomal RNA (srRNA) gene was amplified from Gyroda ctylus salaris using the polymerase chain reaction (PCR), cloned, and the complete gene sequence of 1966 bp determined. The V4 region of the srRNA gene was identified and amplified from single specimens of G. s afaris, G. derjavini and G. truttae. Comparison of the V4 sequences fr om these three species revealed sequence differences from which restri ction fragment length polymorphisms (RFLPs) were predicted and an olig onucleotide probe (GsV4) specific to G. salaris designed. Digestion of the amplified V4 region of the srRNA gene with Hae III and either Alw I, BstY I, Dde I or Mbo I provided a means of discriminating between G. salaris, G. derjavini and G. truttae. The GsV4 probe was used to de tect the srRNA gene from G. salaris in Southern and dot blots of the a mplified V4 region. The nucleotide sequences reported in this paper ha ve been submitted to the EMBL Data Library under accession numbers Z26 942 (G. salaris), Z35128 (G. derjavini) and Z35129 (G. truttae).