Genetic Diversity Studies In Populations Of Fenneropenaeus Chinensis And Marsupenaeus Japonicus And The Molecular Phylogeny Of Solenidae

Sequence comparison and phylogenetic analysis of mtDNA 16S rRNA and COI gene fragments in four species of razor shell were made using PCR and direct sequencing. The four species are Solen grandis Dunker, Solen strictus Gould and Cultellus attenuatus Dunker, Sinonovacula constricta. Nucleotide sequences of 470-481bp for 16S rRNA gene and 658bp for COI gene were obtained respectively. Fourteen indels and 146 variable sites were detected for 16S rRNA gene fragment across the four species. 222 polymorphic sites were detected in COI gene fragments among the four species, with no indels. Genetic distances between S. grandis and S. strictus were 0.0860 (with 16S rRNA gene) and 0.1712 (with COI gene) respectively. Genetic distances between C. attenuatus and Sinonovacula constricta were 0.0937 (with 16S rRNA gene) and 0.1596 (with COI gene) respectively. However, genetic distances between the two Solen species and C. attenuatus, Sinonovacula constricta were significantly larger with both sequence data, with numbers of 0.2778-0.3088 for 16S rRNA gene data, and numbers of 0.2662-0.3125 for COI gene data, respectively. These genetic distances basically reached the level between different families, supporting the opinion of that genus Cultellus should be promoted to family Cultellidae. Sinonovacula constricta were divided into Pharellidae.cytochrome coxidase I gene fragment of 4 populations of Fenneropenaeus chinensis ( 20 for Rushanwan, 20 for Haizhouwan , 19 for chaoxian and 19 for Hanguo ) was amplified via polymerase chain reaction ( PCR ), the PCR products were purified and sequenced . COI gene fragment of 840bp were obtained. The average contents of A,C,G,T is 28.1%, 36.8%, 16.2%, 18.9%, The content of A+T is higher than content of G+C. 17 nucleotide positions were found variable, which included 6 transvertions and 11 transitions, and 19 haplotypes were detected in allsamples. The genetic diversity indexes including S( polymorphic sites), P ( nucleotide diversity ) and K ( average number of nucleotide difference ) were calculated and results indicated that Korea population showed more variation than others and more differences to others, followed by Chaoxian and Haizhouwan population, and Rushanwan population had the least sequence diversity. However, parameters of genetic variation among the four populations indicated that little geographic structure were present. Our data provided baseline information at DNA level on the genetic variation in Fenneropenaeus chinensis populations and may be useful for future management and utilization of the resource.COI gene fragment of Marsupenaeus japonicus of Fujian was amplified via polymerase chain reaction (PCR), The aligned length of COI gene fragment of s was 858bp. 22 nucleotide positions were found variable, which included 20 transitions and 2 transvertions, and 14 haplotypes were detected in all samples. The genetic diversity indexes including S( polymorphic sites ), P ( nucleotide diversity ) and K ( average number of nucleotide difference ) were calculated and results indicated that the genetic diversity of Marsupenaeus japonicus is higher than Fenneropenaeus chinensis.