Molecular Identification And Population Genetic Structure Of The Genus Anisakis From Marine Fishes In The South China Sea

In the present study, the survey of the genus Anisakis from marine fishes in the South China Sea were made.237 larvae of Anisakis were collected from the 1717 fishes (representing 413 species). Molecular identification and population genetic structure of 237 third-stage larvae of Anisakis were analyzed using morphological and molecular tools.1. Molecular identification of the genus Anisakis from marine fishes in the South China SeaBased on technology of PCR-RFLP coupled with sequence analysis,237 samples of Anisakis L3 larvae from the South China Sea are identified as four species, including Anisakis typica, Anisakis pegrefii, Anisakis physeteris and Anisakis sp.HC-2005. In the South China Sea, Anisakis typica is the dominant species of the genus Anisakis. Anisakis sp.HC-2005 is recorded for the first time from China. Restriction fragment length polymorphism patterns of ITS region and the squences of mtDNA coxl of Anisakis sp.HC-2005 were obtained for the first time. The phylogenetic tree of Anisakis was constructed based on the coxl sequences, and the relationship between Anisakis sp.HC-2005 and the congeners were analyzed. Both measurement and morphological characters of the third-stage larvaes are confirm that Anisakis sp.HC-2005 is morphologically different from type II which including A. physeteris and type Ⅰ which including A. typica and A. pegrefii. The infection rate and intensity of Anisakis in the South China Sea were first report, which provide important basic information for the control of anisakiasis.2. Population genetic structure of Anisakis typica from marine fishes in the South China SeaPopulation genetic structure of five populations (Pi, Ey, At, Dm, Tj) of Anisakis typica from marine fishes in the South China Sea was analyzed by PCR-DGGE-coupled sequenceing approach. Sixteen haplotypes (Hap1-Hap 16) of mtDNA coxl were detected which contained fourty-six multiloci. Hap5 and Hap 14 are shared by all populations, which indicats that high level gene flew presents among the five detected populations.The coxl sequences of 16 haplotypes were dealt with by Arlequin 3.1, the results show that the variations of inter-populations (97.92%) is much bigger than that of intra-populations (2.08%). Comparing the populations between Pi and Ey, At, Dm, the value of Fst have a range from 0.05-0.15, indicating that the genetic differentiations among them at a medium level. However, the value of Fst among others are negative, indicating that there is no genetic divergence between them. Phylogentic tree of 16 haplotypes based on the sequence of coxl showed that distribution and differentiation of the haplotypes are unrelated with the host. In general, the levels of genetic differentiations among the 5 populations are relative low, and Anisakis typica larvae in the South China Sea have no host specificity.