Species-specific detection of saffron cod (Eleginus gracilis) eDNA in the Bering and Chukchi seas during the MR20-05C research cruise

To provide an overview of the distribution of saffron cod (Eleginus gracilis) in the Bering and Chukchi Seas, environmental DNA (eDNA) of saffron cod was analyzed using a novel species-specific assay. eDNA samples were collected during the MR20-05C cruise conducted by the 'R/V Mirai' of Japan Agency for Marine-Earth Science and Technology. For eDNA sampling, surface seawater was collected and filtered through a cartridge filter (Sterivex HV, 0.45 m pore size; Millipore, Burlington, MA, USA). Additionally, eDNA samples were obtained from seawater collected at the middle or bottom layer using a Niskin water sampler in the same manner. We designed a species-specific quantitative real-time PCR (qPCR) TaqMan assay that targets the cytochrome b region of mitochondrial DNA to detect specifically saffron cod eDNA. This assay was used to detect and quantify saffron cod DNA in the samples.本研究旨在概述狭鳕（Eleginus gracilis）在白令海与楚科奇海的分布格局，采用新型物种特异性检测方法对狭鳕的环境DNA（environmental DNA, eDNA）开展分析。环境DNA样本采集自日本海洋地球科学技术厅（Japan Agency for Marine-Earth Science and Technology, JAMSTEC）的“未来号”（R/V Mirai）科考船执行的MR20-05C科考航次。针对环境DNA采样，研究人员采集表层海水后，通过筒式过滤器（Sterivex HV，孔径0.45 μm；密理博Millipore，美国马萨诸塞州伯灵顿）完成过滤。此外，本研究还采用相同流程，借助尼斯金采水器（Niskin water sampler）采集中层或底层海水以获取环境DNA样本。本研究设计了一种靶向线粒体DNA细胞色素b区域的物种特异性实时荧光定量PCR（quantitative real-time PCR, qPCR）TaqMan检测体系，可特异性检测狭鳕的环境DNA，并利用该体系对样本中的狭鳕DNA进行定性与定量分析。