Genetics and Morphology Characterize the Dinoflagellate Symbiodinium voratum, n. sp., (Dinophyceae) as the Sole Representative of Symbiodinium Clade E
Dinoflagellates in the genus Symbiodinium are ubiquitous in shallow marine habitats where they commonly exist in symbiosis with cnidarians. Attempts to culture them often retrieve isolates that may not be symbiotic, but instead exist as free‐living species. In particular, cultures of Symbiodinium cl...
Saved in:
| Published in: | The Journal of eukaryotic microbiology Vol. 61; no. 1; pp. 75 - 94 |
|---|---|
| Main Authors: | , , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
United States
Blackwell Publishing Ltd
01-01-2014
|
| Subjects: | |
| Online Access: | Get full text |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Dinoflagellates in the genus Symbiodinium are ubiquitous in shallow marine habitats where they commonly exist in symbiosis with cnidarians. Attempts to culture them often retrieve isolates that may not be symbiotic, but instead exist as free‐living species. In particular, cultures of Symbiodinium clade E obtained from temperate environments were recently shown to feed phagotrophically on bacteria and microalgae. Genetic, behavioral, and morphological evidence indicate that strains of clade E obtained from the northwestern, southwestern, and northeastern temperate Pacific Ocean as well as the Mediterranean Sea constitute a single species: Symbiodinium voratum n. sp. Chloroplast ribosomal 23S and mitochondrial cytochrome b nucleotide sequences were the same for all isolates. The D1/D2 domains of nuclear ribosomal DNA were identical among Western Pacific strains, but single nucleotide substitutions differentiated isolates from California (USA) and Spain. Phylogenetic analyses demonstrated that S. voratum is well‐separated evolutionarily from other Symbiodinium spp. The motile, or mastigote, cells from different cultures were morphologically similar when observed using light, scanning, and transmission electron microscopy; and the first complete Kofoidian plate formula for a Symbiodinium sp. was characterized. As the largest of known Symbiodinium spp., the average coccoid cell diameters measured among cultured isolates ranged between 12.2 (± 0.2 SE) and 13.3 (± 0.2 SE) μm. Unique among species in the genus, a high proportion (approximately 10–20%) of cells remain motile in culture during the dark cycle. Although S. voratum occurs on surfaces of various substrates and is potentially common in the plankton of coastal areas, it may be incapable of forming stable mutualistic symbioses. |
|---|---|
| Bibliography: | National Research Foundation/Ministry of Science, ICT & Future Planning - No. NRF-C1ABA001-2010-0020702 ArticleID:JEU12088 ark:/67375/WNG-LH2F3ZGQ-F Fig. S1. Temperate Pacific Ocean and Mediterranean Sea origins of cultured isolates assigned to Symbiodinium clade E and used in this research to investigate genetic, morphological, ecological, and behavioral traits (designated by solid circles). Open white circles represent additional locals where clade E was reported to be cultured from water samples, but these cultures were not investigated in this study. Fig. S2. Consensus Bayesian tree based on 1,814 bp aligned positions of the small subunit (SSU) region, using the GTR + G + I model with Prorocentrum micans as an outgroup taxa. The parameters were as follows: assumed nucleotide frequency with equal; substitution rate matrix with A-C substitutions = 0.0586, A-G substitutions = 0.2383, A-T substitutions = 0.0869, C-G substitutions = 0.0578, C-T substitutions = 0.5156, G-T substitutions = 0.0428; proportion of sites assumed to be invariable = 0.7004; and rates for variable sites assumed to follow a gamma distribution with shape parameter = 0.0800. The branch lengths are proportional to the amount of character changes. The numbers above the branches indicate the Bayesian posterior probability (left) and maximum likelihood (ML) bootstrap values (right). Posterior probabilities ≥ 0.5 are shown. The rDNA sequences of the strains shown in bold were analyzed in this study. Fig. S3. Consensus Bayesian tree based on 853 bp aligned positions of the internal transcribed spacer 1 (ITS1), 5.8s, and internal transcribed spacer 2 (ITS2) regions, using the GTR + G + I model and Akashiwo sanguinea as an outgroup taxa. The parameters were as follows: assumed nucleotide frequency with equal; substitution rate matrix with A-C substitutions = 0.1038, A-G substitutions = 0.2646, A-T substitutions = 0.1320, C-G substitutions = 0.0625, C-T substitutions = 0.3480, G-T substitutions = 0.0892; proportion of sites assumed to be invariable = 0.1153; and rates for variable sites assumed to follow a gamma distribution with shape parameter = 1.5640. The branch lengths are proportional to the amount of character changes. The numbers above the branches indicate the Bayesian posterior probability (left) and maximum likelihood (ML) bootstrap values (right). Posterior probabilities ≥ 0.5 are shown. Strain EU074907 marked with an asterisk represents a combination of other similar species (EU074916, EU074917, EU074919, EU074920, EU074921, EU074922, EU074923, and EU074924). Fig. S4. Partial psbA and psbAncr alignments identify four distinct haplotypes (hap1-hap4). The start of gray areas indicates regions where chromatograms change abruptly from a high quality to non-interpretable multipeak sequences. Fig. S5. Position of the nucleus in mastigotes of SvFL 1. (A-C) light micrographs of flagellated cells and (D-F) corresponding epi-fluorescent micrographs showing the variable location of DAPI stained nuclei. Fig. S6. Scanning electron micrographs of the motile cell of CCMP 421. (A) Apical view showing the rare example of a cell with seven apical plates. (B) Enlarged figure of apical plate in S4. (C) Apical view showing a cell with six apical plates. (D) Enlarged figure of apical plate in S6. All scale bars = 1 μm. Fig. S7. Scanning electron micrographs of motile cells of SvFL 1. (A) Antapical view showing the hyposome. Micrograph showing a rare cell with seven postcingular plates and heptagonal 2″″ plates. (B). Drawing of antapical view of SvFL 1. (C) Micrograph showing an example of a cell with three antapical plates. (D) Drawing of antapical view of SvFL 1. All scale bars = 1 μm. Fig. S8. The pyrenoid (PY) in the cells of isolates (A) SvFL 1 and (B) CCMP 421 possessed two stalks. The thylakoids from associated chloroplast do not intrude. Table S1. Primers and TaqMan probes for qPCR detection of Symbiodinium voratum (clade E). Table S2. Symbiodinium spp. used to test the cross-reactivity of clade E primers and Taqman probe in qPCR detection. Ecological Disturbance Research Program Korea Institute of Marine Science & Technology Promotion/KMLTM istex:8A79EA2EA39D1DF0FA8104F3FCC09874A2BEC602 The National Science Foundation - No. OCE-0928764 Mid-career Researcher Program - No. 2012-R1A2A2A01010987 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 1066-5234 1550-7408 |
| DOI: | 10.1111/jeu.12088 |