Pilot Study Of Identify And Molecular Evolution Of Several Sea Cucumbers Based On Mitochondrial DNA Sequence

The sea cucumbers, class Holothuroidea, constitute one of the six extant classes of the exclusively marine phylum Echinodermata. The approximately 1200 s pecies of sea cucumbers are partitioned into six orders. Sea cucumber orders are distinguished on the basis of gross morphological characters such as the morphology of the tentacles, the presence or absence of tentacular retractor muscles, the presence or absence of an internal respiratory tree, and the presence and distribution of podia on the trunk. At the familial level, taxonomic distinctions are dependent on a finer level of characters such as the morphology of dermal ossicles, the form of the esophageal calcareous ring, the distribution and morphology of the tube feet, etc. At the species level, the differences in morphological character can be quite subtle, obscuring taxonomic distinctions. Because of the lack of the scientific, methods for detecting processed dried cucumbers, it's necessary to find a simple and accurate way to resolve this problem.Amplified the coded mitochondria protein (cytochrome oxidase subunit 1 COI) genes extracted from Dalian cucumbers, Qingdao cucumbers, Nihon Kandong cucumbers, Nihon Kansai cucumbers, Russian Parastichopus, Holothuria nobilis, Thelenota ananas, Actinopyga echinites. Actinopyga miliaris, Holothuria mexicana by PCR. 650bp-size products were detected by electrophoresis, then purified for cloning and sequencing. The results of sequencing show that the average GC contain is 41.4% to 45.3% and there are no obvious differences among COI fragment of the ten samples. Take the sequencing data of Dalian cucumbers as the standard, we find that there are 163 transition sites in the 652bp for all samples by using MEGA software. There difference of hereditary distance between 16 haplotypes is few, while between Thelenota ananasand other samples is obvious (0.002 to 0.115). According to the NJ and MP system trees based on the calculation of the hereditary distances of samples. The successful amplification of the COI fragment reconfirms the primers are applicable foi Echinodemi. Ru^ia; Parastichopus, Thelenota ananas, Holothuria mexicana can be identified by this method.In this paper, we set up a method that is able to identify a number species of sea cucumbers directly. For other species of sea cucumbers, sequencing is needed.