Tetraselmis jejuensis sp. nov. (Chlorodendrophyceae), a Euryhaline Microalga Found in Supralittoral Tide Pools at Jeju Island, Korea

Abstract

We found the euryhaline microalga, Tetraselmis jejuensis sp. nov., which was adapted to supralittoral tide pools with salinities varying from 0.3–3.1%. Fifteen strains of T. jejuensis were isolated from Daejeong (DJ) and Yongduam (YO), and clonal cultures were established in the laboratory. Morphological characterization revealed that the cells have a compressed shape, four flagella emerging from a depression near the apex in two opposite pairs, a cup-shaped chloroplast containing one pyrenoid surrounded by starch, and eyespot regions not located near the flagellar base. T. jejuensis cells showed distinct characteristics compared to other Tetraselmis species. First, a regular subunit pattern with honeycomb-like structures was predominantly displayed on the surface in the middle of the cell body. Second, the pyrenoid was invaded by both cytoplasmic channels comprising electron-dense material separated from the cytoplasm, and two branches of small cytoplasmic channels (canaliculi) in various directions, which characterize the subgenus Tetrathele. Eyespot regions containing a large number of osmiophilic globules, packed closely together and arranged in subcircular close packing of diverse sizes, were dispersed throughout the chloroplast. In the phylogenetic analysis of small subunit (SSU) rDNA sequences, the 15 strains isolated from DJ and YO separated a newly branched clade in the Chlorodendrophyceae at the base of a clade comprising the T. carteriiformi/subcordiformis clade, T. chuii/suecica clade, and T. striata/convolutae clade. The strains in the diverging clade were considered to belong to the same species. The SSU rDNA sequences of the DJ and YO strains showed a maximum difference of 1.53% and 1.19% compared to Tetraselmis suecica (MK541745), the closest species of the family based on the phylogenetic analysis, respectively. Based on morphological, molecular, and physiological features, we suggest a new species in the genus Tetraselmis named Tetraselmis jejuensis, with the species name “jejuensis” referring to the collection site, Jeju Island, Korea.

Salinity-induced chemical, mechanical, and behavioral changes in marine microalgae

“…Fu et al (2014) showed that the cell volume of D. salina fluctuated continuously for 10 days as a result of high salinity stress, eventually stabilizing at a slightly larger cell size compared to unstressed conditions. The loss of flagella in the cells of T. suecica grown at lower salinity could indicate development of cyst stage, as has been reported for other flagellated microalgae (Borowitzka and Siva 2007;Ma et al 2012;Wei et al 2017;Shetty et al 2019;Hyung et al 2021). On the other hand, the cells of C. closterium were larger compared to cells grown at salinity of 38, presumably not only related to salinity but also to its life cycle, in which the maximal cell size is attained by initial cells sprouting from the fully grown auxospores (Vanormelingen et al 2013).…”

Biodiversity of symbiotic microalgae associated with meiofaunal marine acoels in Southern Japan

“…indica , and T . verrucosa ) have type strains for which both molecular and morphological data is available ( Arora et al, 2013 ; Chantzistrountsiou et al, 2016 ; Hyung et al, 2021 ). Moreover, different sequences with the same name ( T .…”

“…gracilis , and T . chuii ) appear in different clades, further clouding Tetraselmis taxonomy ( Arora et al, 2013 ; Hyung et al, 2021 ). This study established 32 cultures of Tetraselmis from acoels providing a vital resource to address fundamental issues surrounding Tetraselmis taxonomy and systematics.…”

“…The phylogeny and taxonomy of Tetraselmis have mainly been based on pyrenoid or flagella ultrastructure, as their outer appearance can vary ( Butcher, 1959 ; Hori, Norris & Chihara, 1982 , 1983 , 1986 ; Hori & Chihara, 1974 ; Marin, Matzke & Melkonian, 1993 ). Morphological-based phylogeny, however, has been questioned after molecular work revealed multiple species were genetically identical ( Arora et al, 2013 ; Hyung et al, 2021 ). Although Tetraselmis is widespread among acoels (over half of known convolutids contain Tetraselmis symbionts), no research has been performed to clarify the diversity of Tetraselmis species naturally associating with acoels.…”

Harnessing Nature’s nanoSecrets: biocompatibility, biodistribution and bioactivity of extracellular vesicles derived from microalgae

“…Our previous work has shown that nanoalgosomes are small EVs (sEVs), surrounded by a lipid bilayer membrane, containing EV biomarkers and having a typical EV size distribution (about 100 nm) and density 15,16 . We focused on sEVs isolated from the marine photosynthetic chlorophyte Tetraselmis chuii, which is rich in vitamin E, carotenoids, chlorophyll, and tocopherols with anti-inflammatory and antioxidant properties 15,16,[21][22][23] . Our analysis showed that nanoalgosomes are non-cytotoxic and can be taken up by different cellular systems in vitro as well as in vivo by the invertebrate model organism Caenorhabditis elegans (Nematoda), an alternative to the mammalian model, that is faster and less expensive to use and whose body transparency is advantageous for studying nanoparticle toxicity, distribution, and uptake 24 .…”