First Report of the Dinoflagellate Genus Effrenium in the East Sea of Korea: Morphological, Genetic, and Fatty Acid Characteristics

Nam Seon Kang,Min Seok Kwak,Kyeong Mi Kim,Jung A Lee,Eun Song Kim,Moongeun Yoon,Ji Won Hong

doi:10.3390/su12093928

Nam Seon Kang, Min Seok Kwak + Show 5 more

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https://doi.org/10.3390/su12093928

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Abstract

Most species in the family Symbiodiniaceae are symbiotic partners to invertebrate and protist hosts, but a few live freely in water columns. Here, a free-living dinoflagellate was isolated from the waters off the Dokdo Islands in the East Sea of Korea. Morphological and molecular analyses show this isolate belongs to Effrenium voratum. Prior to the present study, E. voratum had been reported to live in the waters in the temperate latitudes in the western North Pacific, the southwest Western Pacific, the eastern North Pacific, the eastern Atlantic, and the Mediterranean Sea. To our knowledge, this is the highest latitude in the western North Pacific, where E. voratum has been reported. This report extends the known range of this dinoflagellate to the temperate waters of the western North Pacific Ocean. The sequence of the D1/D2 region of the large subunit ribosomal DNA (LSU rDNA) was identical to E. voratum found in Jeju Island, Korea, Tsushima Island, Japan, and Cook Strait, New Zealand, suggesting this species is cosmopolitan. However, it was different by 1 bp from those found in Blanes, Spain and Santa Barbara, USA. In the phylogenetic tree built on the basis of the LSU (D1-D2) rDNA region sequences, this dinoflagellate was clustered within a clade, including all the other E. voratum strains. Morphological characteristics were like those of strains found in the waters of Jeju Island. This is the first report conducted on the fatty acid profile of fully characterized E. voratum. Importantly, the isolate possessed a high ratio of long-chain omega-3 polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) relative to total lipid. This dinoflagellate could be a candidate for commercial applications, such as aquaculture feed and essential omega-3 PUFA productions.

Highlights

Dinoflagellates are ubiquitous protists that can be found in almost every conceivable marine environment [1]
The key for differentiating families in the order Suessiales [36] is the morphology of the apical furrow: Species in the family Tovelliaceae have an apical line of narrow plates (ALP), species in the family Borghiellaceae have a pair of elongated anterior vesicles (PEV), and species in the family Symbiodinaceae have a single elongated amphiesmal vesicle (EAV) [37]
Strain MABIKLP88 had the EAV, type E eyespot, and seven latitudinal series of amphiesmal vesicles, these morphologies fit the criteria for the family Symbiodinaceae

Summary

Introduction

Dinoflagellates are ubiquitous protists that can be found in almost every conceivable marine environment [1]. The family Symbiodiniaceae (Order Suessiales) comprises symbiotic dinoflagellates, most of which are symbiotic with invertebrate and protist hosts [12,13,14,15,16,17], even though some species exist as free-living forms [18] These dinoflagellates are vital components of the coral reef ecosystems, and they are promising resources in the production of valuable pigments [19] and toxin compounds, such as zooxanthella toxins [20]. Despite their ecological and economic importance in the marine ecosystems and biotechnology, little information is available on their taxonomy. Accurate identification and establishment of a clonal culture of these dinoflagellates are essential for further research and commercial application

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