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Genetic diversity, morphological uniformity and polyketide production in dinoflagellates (Amphidinium, Dinoflagellata).

Murray SA, Garby T, Hoppenrath M, Neilan BA - PLoS ONE (2012)

Bottom Line: We found that six genetically distinct cryptic species (clades) exist within the species A. massartii and four within A. carterae, and that these clades differ from one another in molecular sequences at levels comparable to other dinoflagellate species, genera or even families.Using primers based on an alignment of alveolate ketosynthase sequences, we isolated partial ketosynthase genes from several Amphidinium species.We compared these genes to known dinoflagellate ketosynthase genes and investigated the evolution and diversity of the strains of Amphidinium that produce them.

View Article: PubMed Central - PubMed

Affiliation: School of Biotechnology and Biomolecular Sciences and Evolution and Ecology Research Centre, University of New South Wales, New South Wales, Sydney, Australia. s.murray@unsw.edu.au

ABSTRACT
Dinoflagellates are an intriguing group of eukaryotes, showing many unusual morphological and genetic features. Some groups of dinoflagellates are morphologically highly uniform, despite indications of genetic diversity. The species Amphidinium carterae is abundant and cosmopolitan in marine environments, grows easily in culture, and has therefore been used as a 'model' dinoflagellate in research into dinoflagellate genetics, polyketide production and photosynthesis. We have investigated the diversity of 'cryptic' species of Amphidinium that are morphologically similar to A. carterae, including the very similar species Amphidinium massartii, based on light and electron microscopy, two nuclear gene regions (LSU rDNA and ITS rDNA) and one mitochondrial gene region (cytochrome b). We found that six genetically distinct cryptic species (clades) exist within the species A. massartii and four within A. carterae, and that these clades differ from one another in molecular sequences at levels comparable to other dinoflagellate species, genera or even families. Using primers based on an alignment of alveolate ketosynthase sequences, we isolated partial ketosynthase genes from several Amphidinium species. We compared these genes to known dinoflagellate ketosynthase genes and investigated the evolution and diversity of the strains of Amphidinium that produce them.

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Light micrographs of Amphidinium massartii strain CS-259 and Amphidinium thermaeum strain CS-109, showing general cell shape, plastid, dividing cells, nucleus, pyrenoid.Scale bars represent 5 µm. (A)–(F), CS-259. (A) A. massartii CS-259 in ventral view, showing shape of the epicone and longitudinal flagellum, arrow points to position of flagellar insertion. (B) Low focus image, arrow points to pyrenoid. (C) Cell in dorsal view showing general cell shape, (D) Motile dividing cells, arrow points to starch-sheathed pyrenoid, (E) Cell in lateral view showing flattening, (F) Cell taken using epifluorescent microscopy, showing the plastid with multiple lobes. (G)–(I), CS-109. (G) Cell in ventral view showing general shape and position of flagellar insertion (arrow), (H), Cell in lateral view, arrow points to flagellar insertion, (I), Motile cells shortly following cell division.
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pone-0038253-g001: Light micrographs of Amphidinium massartii strain CS-259 and Amphidinium thermaeum strain CS-109, showing general cell shape, plastid, dividing cells, nucleus, pyrenoid.Scale bars represent 5 µm. (A)–(F), CS-259. (A) A. massartii CS-259 in ventral view, showing shape of the epicone and longitudinal flagellum, arrow points to position of flagellar insertion. (B) Low focus image, arrow points to pyrenoid. (C) Cell in dorsal view showing general cell shape, (D) Motile dividing cells, arrow points to starch-sheathed pyrenoid, (E) Cell in lateral view showing flattening, (F) Cell taken using epifluorescent microscopy, showing the plastid with multiple lobes. (G)–(I), CS-109. (G) Cell in ventral view showing general shape and position of flagellar insertion (arrow), (H), Cell in lateral view, arrow points to flagellar insertion, (I), Motile cells shortly following cell division.

Mentions: Cells have a long, narrow epicone and are generally rounded in shape (Fig. 1). Cells are 6.0–12.5 µm in length, (mean 9.5, n = 20), 5.0–11.0 µm in width, (mean 8.2, n = 20), L/W ratio is 0.9–1.6 (Fig. 1A–C). Cells have none to very slight dorso-ventral flattening (breadth - 5 um µm). Cell division by binary fission takes place in the motile cell (Fig. 1D). The longitudinal flagellum is inserted ∼0.6 of the way down the cell. There is a prominent ventral ridge running between the positions of flagellar insertion (Fig. 1A, 2D, E). The longitudinal flagellum is relatively wide, approximately 500 nm (Fig. 2E). The nucleus is rounded, in the posterior of the cell. The gymnodinoid pattern of vesicles can be seen in some cells (Fig. 2F). The plastid is single, with narrow or globular lobes radiating from a central region, and contains a clear ring-shaped starch sheathed pyrenoid of approximately 3 µm diameter (Fig. 1F). Metabolic movement was not observed. Simple body scales were observed as flat, approximately oval-shaped ring-like structures of 45–60 nm in length and 25–30 nm in width (Figs. 3A–C). The natural arrangement of the scales could not be observed. We interpret the irregular accumulations of scales inside alveolar vesicles (Fig. 3A) as a preparation artefact (dislocation).


Genetic diversity, morphological uniformity and polyketide production in dinoflagellates (Amphidinium, Dinoflagellata).

Murray SA, Garby T, Hoppenrath M, Neilan BA - PLoS ONE (2012)

Light micrographs of Amphidinium massartii strain CS-259 and Amphidinium thermaeum strain CS-109, showing general cell shape, plastid, dividing cells, nucleus, pyrenoid.Scale bars represent 5 µm. (A)–(F), CS-259. (A) A. massartii CS-259 in ventral view, showing shape of the epicone and longitudinal flagellum, arrow points to position of flagellar insertion. (B) Low focus image, arrow points to pyrenoid. (C) Cell in dorsal view showing general cell shape, (D) Motile dividing cells, arrow points to starch-sheathed pyrenoid, (E) Cell in lateral view showing flattening, (F) Cell taken using epifluorescent microscopy, showing the plastid with multiple lobes. (G)–(I), CS-109. (G) Cell in ventral view showing general shape and position of flagellar insertion (arrow), (H), Cell in lateral view, arrow points to flagellar insertion, (I), Motile cells shortly following cell division.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3366924&req=5

pone-0038253-g001: Light micrographs of Amphidinium massartii strain CS-259 and Amphidinium thermaeum strain CS-109, showing general cell shape, plastid, dividing cells, nucleus, pyrenoid.Scale bars represent 5 µm. (A)–(F), CS-259. (A) A. massartii CS-259 in ventral view, showing shape of the epicone and longitudinal flagellum, arrow points to position of flagellar insertion. (B) Low focus image, arrow points to pyrenoid. (C) Cell in dorsal view showing general cell shape, (D) Motile dividing cells, arrow points to starch-sheathed pyrenoid, (E) Cell in lateral view showing flattening, (F) Cell taken using epifluorescent microscopy, showing the plastid with multiple lobes. (G)–(I), CS-109. (G) Cell in ventral view showing general shape and position of flagellar insertion (arrow), (H), Cell in lateral view, arrow points to flagellar insertion, (I), Motile cells shortly following cell division.
Mentions: Cells have a long, narrow epicone and are generally rounded in shape (Fig. 1). Cells are 6.0–12.5 µm in length, (mean 9.5, n = 20), 5.0–11.0 µm in width, (mean 8.2, n = 20), L/W ratio is 0.9–1.6 (Fig. 1A–C). Cells have none to very slight dorso-ventral flattening (breadth - 5 um µm). Cell division by binary fission takes place in the motile cell (Fig. 1D). The longitudinal flagellum is inserted ∼0.6 of the way down the cell. There is a prominent ventral ridge running between the positions of flagellar insertion (Fig. 1A, 2D, E). The longitudinal flagellum is relatively wide, approximately 500 nm (Fig. 2E). The nucleus is rounded, in the posterior of the cell. The gymnodinoid pattern of vesicles can be seen in some cells (Fig. 2F). The plastid is single, with narrow or globular lobes radiating from a central region, and contains a clear ring-shaped starch sheathed pyrenoid of approximately 3 µm diameter (Fig. 1F). Metabolic movement was not observed. Simple body scales were observed as flat, approximately oval-shaped ring-like structures of 45–60 nm in length and 25–30 nm in width (Figs. 3A–C). The natural arrangement of the scales could not be observed. We interpret the irregular accumulations of scales inside alveolar vesicles (Fig. 3A) as a preparation artefact (dislocation).

Bottom Line: We found that six genetically distinct cryptic species (clades) exist within the species A. massartii and four within A. carterae, and that these clades differ from one another in molecular sequences at levels comparable to other dinoflagellate species, genera or even families.Using primers based on an alignment of alveolate ketosynthase sequences, we isolated partial ketosynthase genes from several Amphidinium species.We compared these genes to known dinoflagellate ketosynthase genes and investigated the evolution and diversity of the strains of Amphidinium that produce them.

View Article: PubMed Central - PubMed

Affiliation: School of Biotechnology and Biomolecular Sciences and Evolution and Ecology Research Centre, University of New South Wales, New South Wales, Sydney, Australia. s.murray@unsw.edu.au

ABSTRACT
Dinoflagellates are an intriguing group of eukaryotes, showing many unusual morphological and genetic features. Some groups of dinoflagellates are morphologically highly uniform, despite indications of genetic diversity. The species Amphidinium carterae is abundant and cosmopolitan in marine environments, grows easily in culture, and has therefore been used as a 'model' dinoflagellate in research into dinoflagellate genetics, polyketide production and photosynthesis. We have investigated the diversity of 'cryptic' species of Amphidinium that are morphologically similar to A. carterae, including the very similar species Amphidinium massartii, based on light and electron microscopy, two nuclear gene regions (LSU rDNA and ITS rDNA) and one mitochondrial gene region (cytochrome b). We found that six genetically distinct cryptic species (clades) exist within the species A. massartii and four within A. carterae, and that these clades differ from one another in molecular sequences at levels comparable to other dinoflagellate species, genera or even families. Using primers based on an alignment of alveolate ketosynthase sequences, we isolated partial ketosynthase genes from several Amphidinium species. We compared these genes to known dinoflagellate ketosynthase genes and investigated the evolution and diversity of the strains of Amphidinium that produce them.

Show MeSH
Related in: MedlinePlus