2020 年 52 巻 p. 1-5
Diplonemea is one of the most abundant and species-rich protist groups in marine environments. However, many lineages are still undescribed. Particularly, little is understood about members of the ‘deep-sea and pelagic diplonemids (DSPD)’ clade. The environmental DNA (eDNA) studies conducted with universal eukaryotic primers have shown that DSPDs were also abundantly distributed in natural environments, but their cultures have not yet been established. For future studies such as mitochondrial genome sequencing, culture establishment is needed. For establishing cultures, it is important to select samples containing a high quantity of diplonemids. In this study, we designed new diplonemid primers for eDNA analysis using a next-generation sequencer, testing its efficiency using eDNA that was extracted from two deep-sea water samples. Out of a total of 58,154 assembled reads, 57,633 reads (i.e. 99.1%) were affiliated with diplonemids by BLAST and reconstructed into 160 representative sequences. Phylogenetic analyses showed that many of the representative sequences (137 sequences, 85.6%) were branched within the DSPD clade and family Hemistasiidae. These findings indicate that the new primers are useful in monitoring diplonemid diversity and acquiring information for the establishment of DSPD cultures.