A molecular tool for detecting prey items of a heterotrophic marine dinoflagellate, Dinophysis rotundata

Abstract

Dinophysis rotundata, a heterotrophic marine dinoflagellate, has been known as an active predator feeding on planktonic ciliates. However, little information is available on the prey species and diversity. We tried to identify its prey organisms by analyzing the intracellular genes of D. rotundata. Five cells of D. rotundata were isolated from the natural sea water collected from Ise Bay, Mie Prefecture, Japan from 2013 to 2016. The isolated cells contained clear food vacuoles, indicating prey cells preserved well in the vacuoles. After washing each cell and putting into a PCR tube, DNA extraction was done. PCR amplification was conducted using a universal primer set. A restriction enzyme which cleaves selectively only D. rotundata DNA was treated to concentrate the prey DNA. More than 200 sequences were analyzed using gene cloning. DNAs of planktonic ciliates such as tintinnid species (Tintinnopsis radix and Helicostomella subulata) and aloricate ciliate species (Strombidinopsis acuminata) was detected from the prey DNA. Moreover, DNAs of radiolarians, bivalves, polychaetes, and rotifers were also included in the prey DNA. These results harvested by this molecular analysis imply that the prey items of D. rotundata are more diverse. Further application of this technique can provide useful data to revise the structure of food webs in planktonic ecosystem.nisms by analyzing the intracellular genes of D. rotundata. Five cells of D. rotundata were isolated from the natural sea water collected from Ise Bay, Mie Prefecture, Japan from 2013 to 2016. The isolated cells contained clear food vacuoles, indicating prey cells preserved well in the vacuoles. After washing each cell and putting into a PCR tube, DNA extraction was done. PCR amplification was conducted using a universal primer set. A restriction enzyme which cleaves selectively only D. rotundata DNA was treated to concentrate the prey DNA. More than 200 sequences were analyzed using gene cloning. DNAs of planktonic ciliates such as tintinnid species (Tintinnopsis radix and Helicostomella subulata) and aloricate ciliate species (Strombidinopsis acuminata) was detected from the prey DNA. Moreover, DNAs of radiolarians, bivalves, polychaetes, and rotifers were also included in the prey DNA. These results harvested by this molecular analysis imply that the prey items of D. rotundata are more diverse. Further application of this technique can provide useful data to revise the structure of food webs in planktonic ecosystem.