Single-strand conformation polymorphism analysis of genetic variation in Labiostrongylus longispicularis from kangaroos

Single-strand conformation polymorphism (SSCP) analysis was employed to scr een for sequence heterogeneity in the second internal transcribed spacer (I TS-2) of ribosomal (r) DNA of Labiostrongylus longispicularis, a parasitic strongylid nematode occuring in some species of kangaroo in different geogr aphical regions of Australia. The results showed that most of the nematodes screened had different SSCP profiles, which were subsequently shown to cor respond to polymorphisms and/or an indel in the ITS-2 sequence. These varia ble sites related mainly to unpaired regions of the predicted secondary str ucture of the precursor rRNA molecule. SSCP profiles could be used to disti nguish L. longispicularis in Macropus robustus robustus (New South Wales) f rom L. longispicularis in Macropus robustus erubescens and Macropus rufus ( South Australia). This difference corresponded to a transversional change i n the ITS-2 sequence at alignment position 82. The study demonstrated clear ly the effectiveness of SSCP analysis for future large-scale population gen etic studies of L. longispicularis in order to test the hypothesis that L. longispicularis from different geographical regions represents multiple sib ling species*.