Yanagimoto Takashi, Kitamura Toru, Kobayashi Takanori
National Research Institute of Fisheries Science, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan.
Mar Genomics. 2012 Sep;7:17-25. doi: 10.1016/j.margen.2012.04.003. Epub 2012 May 29.
Walleye pollock, Theragra chalocogramma, is one of the most important species in the North Pacific and Bering Sea ecosystems. However genetic population structuring of walleye pollock is uncertain. In the present study, genetic variation of walleye pollock collected in several spawning areas ranging from the Japan Sea to the Gulf of Alaska was investigated by DNA analysis. Three regions of the spacer control region, the ND5 and ND6 region (ND complex), and the ND1 and 16S rRNA region (rDNA complex) were amplified using the polymerase chain reaction (PCR). Restriction fragment length polymorphism (RFLP) was conducted on these PCR products and composite haplotypes were calculated. Furthermore, several nuclear DNA regions (actin, Calmodulin, S7 ribosomal protein, creatin kinase, and SypI gene) were investigated to study the stock structure of walleye pollock. It was considered that Calmodulin gene was one of good genetic marker, therefore we conducted SNP analysis for Calmodulin gene by SnaPshot kits. In RFLP analyses, there were no area-specific fragment patterns in the three regions, control region, ND complex and rDNA complex of mtDNA. However compositions of the fragment patterns for the three digested sets, control region/HinfI, rDNA complex/MspI and ND complex/MspI indicated that there are significant differences between around the Japan (Sado-Funka Bay-Wakkanai-Rausu) and the Bering Sea (Western Bering Sea-Nabarin-Atka I.-Bogoslof I). Furthermore, in the case of haplotype frequency, composition showed also significant genetic difference between two areas. Moreover, in Calmodulin analyses, haplotype compositions were changing from western area to eastern area gradually and the results of AMOVA analysis showed that there are interesting differences between western Pacific, western Bering Sea, and eastern Bering Sea. Judging from these results, it was considered that there are three populations of walleye pollock in the Northern Ocean. However, area-specific pattern was not found in some populations in the Northern Ocean. Therefore, we suggested that these populations were related by weak gene flow, and the walleye pollock was formed with meta-population around the Japan and the Bering Sea.
狭鳕，即黄线狭鳕（Theragra chalocogramma），是北太平洋和白令海生态系统中最重要的物种之一。然而，狭鳕的遗传种群结构尚不确定。在本研究中，通过DNA分析对从日本海到阿拉斯加湾的几个产卵区采集的狭鳕的遗传变异进行了调查。使用聚合酶链反应（PCR）扩增间隔控制区、ND5和ND6区域（ND复合体）以及ND1和16S rRNA区域（rDNA复合体）这三个区域。对这些PCR产物进行限制性片段长度多态性（RFLP）分析并计算复合单倍型。此外，还研究了几个核DNA区域（肌动蛋白、钙调蛋白、S7核糖体蛋白、肌酸激酶和SypI基因）以研究狭鳕的种群结构。认为钙调蛋白基因是一个良好的遗传标记，因此我们使用SnaPshot试剂盒对钙调蛋白基因进行了SNP分析。在RFLP分析中，线粒体DNA的控制区、ND复合体和rDNA复合体这三个区域没有区域特异性的片段模式。然而，控制区/HinfI、rDNA复合体/MspI和ND复合体/MspI这三组消化产物的片段模式组成表明，日本周边（佐渡-文加湾-稚内-罗臼）和白令海（白令海西部-纳巴林-阿图尔岛-博戈斯洛夫岛）之间存在显著差异。此外，在单倍型频率方面，两个区域的组成也显示出显著的遗传差异。而且，在钙调蛋白分析中，单倍型组成从西部地区到东部地区逐渐变化，AMOVA分析结果表明西太平洋、白令海西部和白令海东部之间存在有趣的差异。从这些结果判断，认为在北冰洋存在三个狭鳕种群。然而，在北冰洋的一些种群中未发现区域特异性模式。因此，我们认为这些种群通过微弱的基因流相互关联，狭鳕是在日本和白令海周边由复合种群形成的。
