Combined ribosomal DNA and morphological analysis of individual gyrodactylid monogeneans

A method is presented for the isolation and analysis of hamuli, marginal ho oks, and bars from individual gyrodactylid monogeneans using scanning elect ron microscopy (SEM), while simultaneously processing parasites for I DNA a nalysis using: the polymerase chain reaction (PCR). The haptors of ethanol- fixed gyrodactylids were protease digested to liberate hooks for SEM, where as DNA extracted from the bodies was used for PCR. The method resulted in h ooks and hamuli being prepared from more than 90% of Gyrodactylus turnbulli individuals, a significant improvement on previously published digestion-b ased SEM techniques. PCR on the same parasites was less successful, but seq uence data were obtained from 50% of individuals. Amplification of rDNA int ernal-transcribed spacer regions from individual worms used for SEM gave PC R products consistent with those predicted from our previous sequence analy sis. This method allows the correlation of morphology and DNA sequence from the same individual and can be applied to ethanol-fixed material, such as field-collected and museum specimens.