褐斜鲽(Plagiopsetta glossa)线粒体基因组特征及重排机制研究

冠鲽科(Samaridae)隶属于鲽形目(Pleuronectiformes), 包含冠鲽属(Samaris)、沙鲽属(Samariscus)和斜鲽属(Plagiopsetta)。目前研究表明, 冠鲽(Samaris cristatus)和满月沙鲽(Samariscus latus)的线粒体基因组结构都有重排, 并且两者的基因数量也有差别。为检测斜鲽属鱼类中是否也有不同的特征结构, 我们选用褐斜鲽(Plagiopsetta glossa)作为代表种进行斜鲽属鱼类线粒体基因组特征分析, 同时与冠鲽属及沙鲽属鱼类的线粒体基因组特征进行对比。分析显示, 褐斜鲽的线粒体基因组全长为18723bp, 包括39个基因: 13个蛋白基因、24个tRNA基因、2个rRNA基因、2个控制区、1个轻链复制起点和比典型基因组多的13个间隔子。和经典鱼类的线粒体基因组相比, 褐斜鲽和满月沙鲽都多了tRNA-Cys和tRNA-Tyr两个tRNA, 冠鲽只多了tRNA-Cys, 且3个种类都多了一个控制区, 但褐斜鲽与满月沙鲽的基因排列顺序相同。褐斜鲽线粒体基因的重排导致不同位置的6个tRNA形成了六连体基因簇“tRNA-Cys₁-Tyr₁- Ser1-Lys-Arg-Ser2”, “ND5-ND6-Glu-Cytb-Thr”则位于六连体之后, 但这11个基因相对的排序没有发生变化。采用双复制随机丢失模型(double replications and random loss, DRRL)对褐斜鲽基因的重排现象进行分析, 认为该鱼类基因数量、排列顺序以及比典型基因组多13个间隔子等特征为该模型提供了新的依据。

Characteristic analysis of the complete mitogenome of Plagiopsetta glossa and a possible mechanism for gene rearrangement

The family Samaridae in Pleuronectiformes consists of three genera, namely, Plagiopsetta, Samariscus and Samaris. Studies on mitochondrial genomes of Samaris cristatus and Samariscus latus showed that there exist differences in genomic rearrangement and gene number between this two species. To determine whether there are structural differences in the species of the genus Plagiopsetta, Plagiopsetta glossa were used as the representative species for this study, and the mitochondrial genomic characteristics of this species were compared with those of Samariscus and Samaris. The length of its mitogenome is 18,723 bp, and contains 39 genes, including 13 protein-coding genes, two rRNA genes, 24 tRNA genes, two control regions, one light strand replication origin, and 13 more interspaces. Compared with the typical mitogenome in teleosts, P. glossa and S. latus have two more genes of tRNA-Cys and tRNA-Tyr (S. cristatus only one more tRNA-Cys). Additionally, each of the three flatfish has an extra control region, but the gene orders of P. glossa and S. latus mitogenomes are the same. Six genes (tRNA-Cys₁, tRNA-Tyr₁, tRNA-Ser1, tRNA-Lys, tRNA-Arg, and tRNA-Ser2) from different locations are clustered together forming a gene cluster, and following by this genes cluster was ND5-ND6-Glu-Cytb-Thr, all those 11 genes have no gene order change in terms of typical mitogenome.