Senquence Analysis Of 18S RRNA And Cyt B Gene Of Some Spieces In Cinidaria From Zhejiang

Hydras , sea anemones, corals, and jellyfish belong to the phylum Cnidaria (formerly called Coelenterata). Cnidaria has a very simple body organization, which have two body layers. Cnidaria plays a important role during animal evolutionary process. Taxonomic relationships within the Phylum Cnidaria are nomally pursued based upon few morphological characters, such as species morphology, life history, tentacle shape and number, the number and arrangement of divisions within the gastrovascular cavity (termed mesenteries or septa), the nematocyst structure, and skeletal structure. The significance of any given character is controversial. A variety of taxonomic classification systems have arisen with differing interpretations of the significance of these characters. It's important to find a practical method for Taxonomy in invertebrate.The 18S rRNA gene has enough phylogenetic informations to distinguish among the major groupings within the Class Anthozoa. Cytochrome b gene sequences are often used as population-level genetic markers and have also been used to estimate absolute divergence times between taxa which have close relationship. We determined the taxonomic status of some species in cnidaria from Zhejiang by sequencing and analyzing the two genetic marker. All analysis were performed using MEGA3 software. An initial distance analysis of the entire data was performed using a Kimura two-parameter model. The phylogenetic trees constructed by two method (NJ and MP) based on previous bootstrap analyses.The main results are as follows:1. According to sequence alignment, the 18S rRNA gene sequences of Porpita porpita of Zhengjiang are the most similar to that of one Porpita sp.( AF358086) and the similarity percent is 99.8%. It indicated that Porpita porpita of Zhengjiang belongs neither to the order Siphonophora nor to the order Chondrophora .but belongs to the order Anthomedusae,based upon both of the NJ and MP tree.with bootstrap value 100%. We suggested that Porpita porpita of Zhejiang is a species of Anthomedusae.2. The 18S rRNA gene sequences of Haliplanella luciae of Xiangshan and Ninghai are both most similar to that of Haliplanella luciae(AJ133554) in GeneBank and the similarity percent are 99%.The topology of NJ and MP treesupport that the two Haliplanella luciae are species of Diadumenidae. The conclusions are consistent with the result of morphological taxonomy.3. According to the results of sequence alignmenUhe partial Cyt b gene sequence of Actiniidae actinia equine, Anthopleura xanthogrammica and Anthopleura midori are similar to Metridium .yem7e(AF000023) of Actiniidae and similarity percent are 88%, 87.6% and 86.9%.,and all of them are in the same clade on phylogenetic trees(NJ and MP).It just as the result of morphological taxonomy,all of them are species of Actiniidae.4. Edwardsia sipunculoides is belong to the order Edwardsidae in being, however.it first assemble with species of Actiniidae in the same clade on the phylogenetic trees(NJ and MP),and not with the species of Edwardsidae. We suggested to rename the Edwardsia sipunculoides as Actiniidae sipunculoides.5. We considered that the 18S rRNA and Cyt b gene are sufficient phylogenetic signal for determining taxonomic relationship in cnidaria, although the taxonomy based on sequence analysis of 18S rRNA and Cyt b gene of some species of cndaria from Zhejiang are not entirely consistent with the result of morphological taxonomy, and the Cyt b gene is more efficiency to estimate absolute divergence times between closely related taxa.6. 2>