Jiangsu Key Laboratory of Marine Biotechnology, College of Marine Science, Huaihai Institute of Technology, Lianyungang 222005, China.
Genome. 2011 Nov;54(11):911-22. doi: 10.1139/g11-053. Epub 2011 Oct 21.
Euphausiid krill are dominant organisms in the zooplankton population and play a central role in marine ecosystems. Euphausia pacifica (Malacostraca: Euphausiacea) is one of the most important and dominant crustaceans in the North Pacific Ocean. In this paper, we described the gene content, organization, and codon usage of the E. pacifica mitochondrial genome. The mitochondrial genome of E. pacifica is 16 898 bp in length and contains a standard set of 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes. Translocation of three transfer RNAs (trnL(1), trnL(2), and trnW) was found in the E. pacifica mitochondrial genome when comparing with the pancrustacean ground pattern. The rate of K(a)/K(s) in 13 protein-coding genes among three krill is much less than 1, which indicates a strong purifying selection within this group. The largest noncoding region in the E. pacifica mitochondrial genome contains one section with tandem repeats (4.7 x 154 bp), which are the largest tandem repeats found in malacostracan mitochondrial genomes so far. All analyses based on nucleotide and amino acid data strongly support the monophyly of Stomatopoda, Penaeidae, Caridea, Brachyura, and Euphausiacea. The Bayesian analysis of nucleotide and amino acid datasets strongly supports the close relationship between Euphausiacea and Decapoda, which confirms traditional findings. The maximum likelihood analysis based on amino acid data strongly supports the close relationship between Euphausiacea and Penaeidae, which destroys the monophyly of Decapoda.
磷虾是浮游动物种群中的优势生物，在海洋生态系统中起着核心作用。太平洋磷虾（软甲纲：磷虾目）是北太平洋最重要和最占优势的甲壳类动物之一。在本文中，我们描述了太平洋磷虾线粒体基因组的基因含量、组织和密码子使用情况。太平洋磷虾的线粒体基因组长 16898bp，包含一套标准的 13 个蛋白质编码基因、2 个核糖体 RNA 基因和 22 个转移 RNA 基因。与泛甲壳动物的模式相比，在太平洋磷虾的线粒体基因组中发现了三个转移 RNA（trnL(1)、trnL(2)和 trnW）的易位。在 13 个蛋白质编码基因中，三种磷虾的 K(a)/K(s) 比率均远小于 1，表明该组内存在强烈的纯化选择。太平洋磷虾线粒体基因组中最大的非编码区包含一个串联重复区（4.7×154bp），这是迄今为止在软甲类动物线粒体基因组中发现的最大串联重复区。基于核苷酸和氨基酸数据的所有分析都强烈支持十足目、对虾科、磷虾目、短尾亚目和磷虾目是单系的。核苷酸和氨基酸数据集的贝叶斯分析强烈支持磷虾目和十足目之间的密切关系，这证实了传统的发现。基于氨基酸数据的最大似然分析强烈支持磷虾目和对虾科之间的密切关系，这破坏了十足目的单系性。
