State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, China.
PLoS One. 2012;7(7):e42172. doi: 10.1371/journal.pone.0042172. Epub 2012 Jul 26.
Complete mitochondrial (mt) genomes and the gene rearrangements are increasingly used as molecular markers for investigating phylogenetic relationships. Contributing to the complete mt genomes of Gastropoda, especially Pulmonata, we determined the mt genome of the freshwater snail Galba pervia, which is an important intermediate host for Fasciola spp. in China. The complete mt genome of G. pervia is 13,768 bp in length. Its genome is circular, and consists of 37 genes, including 13 genes for proteins, 2 genes for rRNA, 22 genes for tRNA. The mt gene order of G. pervia showed novel arrangement (tRNA-His, tRNA-Gly and tRNA-Tyr change positions and directions) when compared with mt genomes of Pulmonata species sequenced to date, indicating divergence among different species within the Pulmonata. A total of 3655 amino acids were deduced to encode 13 protein genes. The most frequently used amino acid is Leu (15.05%), followed by Phe (11.24%), Ser (10.76%) and IIe (8.346%). Phylogenetic analyses using the concatenated amino acid sequences of the 13 protein-coding genes, with three different computational algorithms (maximum parsimony, maximum likelihood and bayesian analysis), all revealed that the families Lymnaeidae and Planorbidae are closely related two snail families, consistent with previous classifications based on morphological and molecular studies. The complete mt genome sequence of G. pervia showed a novel gene arrangement and it represents the first sequenced high quality mt genome of the family Lymnaeidae. These novel mtDNA data provide additional genetic markers for studying the epidemiology, population genetics and phylogeographics of freshwater snails, as well as for understanding interplay between the intermediate snail hosts and the intra-mollusca stages of Fasciola spp..
完整的线粒体 (mt) 基因组和基因重排越来越多地被用作研究系统发育关系的分子标记。本研究旨在为腹足纲（尤其是肺螺亚纲）动物的完整 mt 基因组测序贡献力量，我们测定了中国重要的肝片吸虫中间宿主淡水贝类圆口铜螺（Galba pervia）的 mt 基因组。圆口铜螺的 mt 基因组全长为 13768bp，为环状分子，包含 37 个基因，包括 13 个蛋白编码基因、2 个 rRNA 基因和 22 个 tRNA 基因。与迄今为止测序的肺螺亚纲物种 mt 基因组相比，圆口铜螺 mt 基因的排列具有新颖的特征（tRNA-His、tRNA-Gly 和 tRNA-Tyr 的位置和方向发生改变），表明肺螺亚纲不同物种之间存在分化。总共推断出 3655 个氨基酸来编码 13 个蛋白基因。使用频率最高的氨基酸是亮氨酸（15.05%），其次是苯丙氨酸（11.24%）、丝氨酸（10.76%）和异亮氨酸（8.346%）。使用三种不同的计算算法（最大简约法、最大似然法和贝叶斯分析法）对 13 个蛋白编码基因的氨基酸序列进行联合分析，结果均表明圆口铜螺所在的圆口螺科和扁卷螺科是密切相关的两个螺科，这与基于形态学和分子研究的分类结果一致。圆口铜螺的完整 mt 基因组序列显示出新颖的基因排列，这是首次报道的圆口螺科高质量 mt 基因组序列。这些新的 mtDNA 数据为研究淡水贝类的流行病学、种群遗传学和系统地理学，以及了解中间宿主蜗牛与肝片吸虫内部软体动物阶段之间的相互作用提供了额外的遗传标记。
