节织纹螺(Nassarius hepaticus)贝壳差异的COⅠ基因分析

选择在厦门港市场购买的节织纹螺(Nassarius hepaticus),挑选五种典型贝壳形态,每种形态各5个个体,研究其COⅠ基因序列及其分子系统发育。结果表明,节织纹螺五种贝壳类型的齿舌形态基本一致,但个体间齿列数和中央齿上缘小齿数有差异;COⅠ基因序列存在较大的变异,678—679bp的片段上有31个变异位点,其中20个为密码子第三位碱基,6个为密码子第二位碱基,5个为密码子第一位碱基;贝壳、齿舌变异与DNA变异不存在关系,同类型和不同类型的个体在DNA序列上差异较小,根据Kimura 2-parameter法计算25个个体的遗传距离在0.001—0.010之间,平均值为0.007。以COⅠ基因序列计算的遗传距离和构建的系统发育树证实五种贝壳形态的25个个体同属于节织纹螺。

THE CO I GENE OF DIFFERENT SHELL SHAPES OF NASSARIUS HEPATICUS

The CO Ⅰ gene sequences and phylogeny of five groups of shell morphs of Nassarius hepaticus from 25 samples taken from Xiamen market were studied. The radula morphologies of the five groups of shell morphs were similar but rows of teeth and cusps on the central tooth varied between individuals. The fragment of CO Ⅰ gene was 678-679bp in length, in which 31 sites were variable, and 20 sites, 6 sites and 5 sites occurred in the third, second and first codon posi-tion, respectively. The relationship between shell morphology and CO Ⅰ gene sequences was not strong. For individuals of all shell morphs, DNA sequences were similar. The heredity distance ranged from 0.001 to 0.010, with an average of 0.007.The heredity distance and CO Ⅰ phylogenetic tree indicated that all the morphological samples are the same species,namely Nassarius hepaticus.