长江华溪蟹β-actin 基因cDNA扩增及分子系统发育初步分析

Amplification of cDNA and primary molecular phylogeny based on β-actin gene sequences of a freshwater crab, Sinopotamon yangtsekiense

摘要:

利用RT-PCR技术，扩增了长江华溪蟹(Sinopotamon yangtsekiense)β-actin基因片段，测序并结合GenBank数据库中蓝蟹（Callinectes sapidus）、中华绒螯蟹（E.sinensis）、黑背地蟹（Gecarcinus lateralis）、张口蟹（Neohelice granulata）、远海梭子蟹（Portunus pelagicus）、锯缘青蟹（Scylla serrata）6种蟹的同源序列进行比较。结果显示：在长为338 bp的β-actin同源序列中有115个变异位点，57个单碱基变化位点。7种蟹的种间核苷酸变异值从1.6％到25.3％，碱基替换比值从0.740到4.050，其中锯缘青蟹和远海梭子蟹亲缘关系很近，长江华溪蟹和地蟹、张口蟹亲缘关系较远，而中华绒螯蟹和远海梭子蟹关系较远。用NJ法和ML法构建了分子系统树，得到了相同的拓扑结构。系统发育分析表明长江华溪蟹单独形成一支，与其它海洋蟹的亲缘关系远，支持溪蟹单独划分总科。锯缘青蟹和远海梭子蟹先聚在一起，然后和黑背地蟹聚在一起，再和弓蟹科的张口蟹聚在一起，与传统形态学分类系统稍有不同。

Abstract:

Amplification and sequence of the β-actin gene of Sinopotamon yangtsekiense were conducted with the reverse transcription polymerase chain reaction (RTPCR). It is aligned with homologous sequences of 6 other crabs from GenBank. The results showed there were 115 variable sites and 57 singleton sites in β-actin homologous sequences of 338 bp. Substitution rates among nucleotide sites were from 1.6％ to 25.3％ and the numbers of nucleotide transitions / transversions were from 0.740 to 4.050. Scylla serrata was more closely related to the sand crab Portunus pelagicus than any other species. S.yangtsekiense was farther related to Gecarcinus lateralis， Neohelice granulate. Furthermore,Eriocheir sinensis was farther related to P.pelagicus. The phylogenetic trees constructed by neighbor joining (NJ) and maximum likelihood (ML) supported the same topology. The phylogenetic analysis implied that S.yangtsekiense was singleton branch, far away from other marine crabs, so it should belong to potamidea. S.serrata was clustered with P.pelagicus firstly, clustered with G.lateralis consequently and then N.granulate was clustered into them. The results of inferred phylogeny were different from traditional classification scheme based on morphology.