SSCP-based identification of members within the Pseudoterranova decipiens complex (Nematoda: Ascaridoidea: Anisakidae) using genetic markers in the internal transcribed spacers of ribosomal DNA

• Published in: Parasitology
• Main Authors: ZHU, X. Q., D'AMELIO, S., PALM, H. W., PAGGI, L., GEORGE-NASCIMENTO, M., GASSER, R. B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2002
• Subjects: Antarc*; Antarctica; Icefish
• Online Access: http://dx.doi.org/10.1017/s0031182002001579; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0031182002001579

The anisakid nematodes morphologically corresponding with Pseudoterranova decipiens sensu lato ( s.l. ) (Krabbe, 1878) from different seal or sea lion hosts and geographical origins, previously identified as Pseudoterranova krabbei , P. decipiens ( s.s. ), P. bulbosa , P. azarasi and P. cattani by multilocus enzyme electrophoresis, were characterized using a DNA approach. Also a population of P. decipiens ( s.l. ) from Chaenocephalus aceratus , the blackfin icefish, from Antarctica and another from Osmerus eperlanus , the European smelt, from Germany were included in the study. The first (ITS-1) and second (ITS-2) internal transcribed spacers (ITS) of ribosomal DNA (rDNA) were amplified by PCR from individual nematodes and analysed by single-strand conformation polymorphism (SSCP), followed by selective sequencing. While no variation in single-stranded ITS-1 and ITS-2 profiles was detected among samples representing each of the species or populations (with the exception of slight microheterogeneity), SSCP analysis of the ITS-2 amplicons allowed the unequivocal differentiation of all of the 5 sibling species of P. decipiens ( s.l. ) examined, which was supported by sequence differences in ITS rDNA. Samples representing the P. decipiens ( s.l. ) population from O. eperlanus had the same SSCP profile as those of P. decipiens ( s.s. ), which was supported by a lack of nucleotide difference in the ITS between them, suggesting that the former represented P. decipiens ( s.s. ). Based on SSCP results and ITS sequence data, P. decipiens ( s.l. ) from C. aceratus was genetically most distinct with respect to all other members of Pseudoterranova examined, which indicated that it may represent P. decipiens E (based on geographical origin) or a distinct species. These findings and the molecular approach taken should have important implications for studying the life-cycles, transmission patterns, epidemiology and population genetics of these anisakid nematodes, and the diagnosis of their infections.