Ribosomal RNA characterization of non-transcribed spacer and two internal transcribed spacers with 5.8S ribosomal RNA of Perkinsus sp. found in undulated surf clams (Paphia undulata) from Thailand

Abstract

The genetic divergence of Perkinsus sp. found in the undulated surf clam (Paphia undulata) from the Gulf of Thailand and other known Perkinsus species was examined using the non-transcribed spacer and two internal transcribed spacers with 5.8 S rRNA gene. The sequences of non-transcribed spacer (NTS) and internal transcribed spacer region (ITS) that includes the 5.8S rRNA gene flanked by ITS1 and ITS2 (ITS1-5.8S-ITS2) were cloned and sequenced. The sequences were compared with those of Perkinsus olseni from Australia, P. atlanticus from Korea, P. marinus and P. andrewsi from the United States and P. qugwadi from Canada. The lengths of the obtained nucleotide sequences of NTS, ITS-1 5.8S rRNA and ITS-2 were 1,167, 183, 159, and 371 bp, respectively. The nucleotide sequences of NTS and ITS-5.8S rRNA of Thai Perkinsus and P. olseni showed 98.69% and 99.85% identity, respectively. When compared with P. atlanticus identities were 96.27 and 99.71%, in P. marinus 75.38 and 94.88% and in P. andrewsi 46.55 and 86.23%. The nucleotide sequences of ITS-5.8S rRNA between Thai Perkinsus and P. chesapeaki showed an identity of 87.05%. This is the first report of the occurrence of Perkinsus sp in the Gulf of Thailand.