Fisheries College, Ocean University of China, Qingdao, China ; College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China.
Fisheries College, Ocean University of China, Qingdao, China ; Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.
PLoS One. 2013 Dec 17;8(12):e84216. doi: 10.1371/journal.pone.0084216. eCollection 2013.
In the present study, we determined the complete mitochondrial DNA (mtDNA) sequences of two species of Cistopus, namely C. chinensis and C. taiwanicus, and conducted a comparative mt genome analysis across the class Cephalopoda. The mtDNA length of C. chinensis and C. taiwanicus are 15706 and 15793 nucleotides with an AT content of 76.21% and 76.5%, respectively. The sequence identity of mtDNA between C. chinensis and C. taiwanicus was 88%, suggesting a close relationship. Compared with C. taiwanicus and other octopods, C. chinensis encoded two additional tRNA genes, showing a novel gene arrangement. In addition, an unusual 23 poly (A) signal structure is found in the ATP8 coding region of C. chinensis. The entire genome and each protein coding gene of the two Cistopus species displayed notable levels of AT and GC skews. Based on sliding window analysis among Octopodiformes, ND1 and DN5 were considered to be more reliable molecular beacons. Phylogenetic analyses based on the 13 protein-coding genes revealed that C. chinensis and C. taiwanicus form a monophyletic group with high statistical support, consistent with previous studies based on morphological characteristics. Our results also indicated that the phylogenetic position of the genus Cistopus is closer to Octopus than to Amphioctopus and Callistoctopus. The complete mtDNA sequence of C. chinensis and C. taiwanicus represent the first whole mt genomes in the genus Cistopus. These novel mtDNA data will be important in refining the phylogenetic relationships within Octopodiformes and enriching the resource of markers for systematic, population genetic and evolutionary biological studies of Cephalopoda.
在本研究中，我们测定了两种中国石首鱼（Cistopus），即中华石首鱼（C. chinensis）和台湾石首鱼（C. taiwanicus）的完整线粒体 DNA（mtDNA）序列，并对头足纲（Cephalopoda）的 mt 基因组进行了比较分析。C. chinensis 和 C. taiwanicus 的 mtDNA 长度分别为 15706 和 15793 个核苷酸，A+T 含量分别为 76.21%和 76.5%。C. chinensis 和 C. taiwanicus 的 mtDNA 序列同一性为 88%，表明它们之间存在密切的亲缘关系。与 C. taiwanicus 和其他章鱼相比，C. chinensis 编码了两个额外的 tRNA 基因，表现出一种新的基因排列。此外，在 C. chinensis 的 ATP8 编码区发现了一种不寻常的 23 个多聚（A）信号结构。这两个中国石首鱼物种的整个基因组和每个蛋白质编码基因都表现出显著的 AT 和 GC 倾斜。基于 Octopodiformes 之间的滑动窗口分析，ND1 和 DN5 被认为是更可靠的分子信标。基于 13 个蛋白质编码基因的系统发育分析表明，C. chinensis 和 C. taiwanicus 形成一个单系群，具有高度的统计支持，与基于形态特征的先前研究一致。我们的结果还表明，中国石首鱼属的系统发育位置更接近章鱼属，而不是 Amphioctopus 和 Callistoctopus。中华石首鱼和台湾石首鱼的完整 mtDNA 序列代表了中国石首鱼属的首个完整 mt 基因组。这些新的 mtDNA 数据将有助于完善 Octopodiformes 内部的系统发育关系，并丰富头足类系统学、群体遗传学和进化生物学研究的标记资源。
