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Ultra-high voltage electron microscopy of primitive algae illuminates 3D ultrastructures of the first photosynthetic eukaryote.

Takahashi T, Nishida T, Saito C, Yasuda H, Nozaki H - Sci Rep (2015)

Bottom Line: The primary phototrophs, glaucophytes, are thought to retain ancestral features of the first photosynthetic eukaryote, but examining the protoplast ultrastructure has previously been problematic in the coccoid glaucophyte Glaucocystis due to its thick cell wall.This 3D feature is essentially identical to that of another glaucophyte genus Cyanophora, as well as the secondary phototrophs in Alveolata.Thus, the common ancestor of glaucophytes and/or the first photosynthetic eukaryote may have shown similar 3D structures.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

ABSTRACT
A heterotrophic organism 1-2 billion years ago enslaved a cyanobacterium to become the first photosynthetic eukaryote, and has diverged globally. The primary phototrophs, glaucophytes, are thought to retain ancestral features of the first photosynthetic eukaryote, but examining the protoplast ultrastructure has previously been problematic in the coccoid glaucophyte Glaucocystis due to its thick cell wall. Here, we examined the three-dimensional (3D) ultrastructure in two divergent species of Glaucocystis using ultra-high voltage electron microscopy. Three-dimensional modelling of Glaucocystis cells using electron tomography clearly showed that numerous, leaflet-like flattened vesicles are distributed throughout the protoplast periphery just underneath a single-layered plasma membrane. This 3D feature is essentially identical to that of another glaucophyte genus Cyanophora, as well as the secondary phototrophs in Alveolata. Thus, the common ancestor of glaucophytes and/or the first photosynthetic eukaryote may have shown similar 3D structures.

No MeSH data available.


Related in: MedlinePlus

Electron tomography and 3D-modelling of protoplast periphery of Glaucocystis nostochinearum SAG 16.98 vegetative cell.Corresponding to Supplementary Movies 3 and 4. (a) Ultra-high voltage electron microscopic image. Inset shows higher magnification image of the cell periphery (boxed area). Scale bar, 5 μm and 1 μm (inset). (b) Tomographic image of boxed area in (a). Note that the plasma membrane lacks deep grooves at section. Scale bar, 1 μm. M, mitochondrion; P, plastid; V, vacuole; W, cell wall. (c–g) 3D images showing distribution of plasma membrane (magenta), and underlying flattened vesicles (yellow) associated with microtubules (green) on cytoplasmic side. Not to scale. Note that plasma membrane and flattened vesicles exhibit almost smooth surfaces. Arrowheads indicate slight overlapping of neighbouring flattened vesicles. (c) View with a tomographic image. For abbreviations of organelles, see (b). (d,e) View from the cell wall side. (f,g) View from the cytoplasmic side.
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f3: Electron tomography and 3D-modelling of protoplast periphery of Glaucocystis nostochinearum SAG 16.98 vegetative cell.Corresponding to Supplementary Movies 3 and 4. (a) Ultra-high voltage electron microscopic image. Inset shows higher magnification image of the cell periphery (boxed area). Scale bar, 5 μm and 1 μm (inset). (b) Tomographic image of boxed area in (a). Note that the plasma membrane lacks deep grooves at section. Scale bar, 1 μm. M, mitochondrion; P, plastid; V, vacuole; W, cell wall. (c–g) 3D images showing distribution of plasma membrane (magenta), and underlying flattened vesicles (yellow) associated with microtubules (green) on cytoplasmic side. Not to scale. Note that plasma membrane and flattened vesicles exhibit almost smooth surfaces. Arrowheads indicate slight overlapping of neighbouring flattened vesicles. (c) View with a tomographic image. For abbreviations of organelles, see (b). (d,e) View from the cell wall side. (f,g) View from the cytoplasmic side.

Mentions: Using UHVEM tomography, the 3D ultrastructural features of the plasma membrane and the flattened vesicles at the protoplast periphery of the two Glaucocystis species were visualised with high contrast (Figs 2 and 3 and Supplementary Movies 1,2,3,4). In both species, the flattened vesicles were leaflet-like in shape, lacked a plate-like interior structure, and were distributed throughout the entire protoplast periphery just underneath the single-layered plasma membrane (except for the region near basal bodies; see below), but did not completely enclose the protoplast periphery to form small spaces between the vesicles at the protoplast periphery.


Ultra-high voltage electron microscopy of primitive algae illuminates 3D ultrastructures of the first photosynthetic eukaryote.

Takahashi T, Nishida T, Saito C, Yasuda H, Nozaki H - Sci Rep (2015)

Electron tomography and 3D-modelling of protoplast periphery of Glaucocystis nostochinearum SAG 16.98 vegetative cell.Corresponding to Supplementary Movies 3 and 4. (a) Ultra-high voltage electron microscopic image. Inset shows higher magnification image of the cell periphery (boxed area). Scale bar, 5 μm and 1 μm (inset). (b) Tomographic image of boxed area in (a). Note that the plasma membrane lacks deep grooves at section. Scale bar, 1 μm. M, mitochondrion; P, plastid; V, vacuole; W, cell wall. (c–g) 3D images showing distribution of plasma membrane (magenta), and underlying flattened vesicles (yellow) associated with microtubules (green) on cytoplasmic side. Not to scale. Note that plasma membrane and flattened vesicles exhibit almost smooth surfaces. Arrowheads indicate slight overlapping of neighbouring flattened vesicles. (c) View with a tomographic image. For abbreviations of organelles, see (b). (d,e) View from the cell wall side. (f,g) View from the cytoplasmic side.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4593968&req=5

f3: Electron tomography and 3D-modelling of protoplast periphery of Glaucocystis nostochinearum SAG 16.98 vegetative cell.Corresponding to Supplementary Movies 3 and 4. (a) Ultra-high voltage electron microscopic image. Inset shows higher magnification image of the cell periphery (boxed area). Scale bar, 5 μm and 1 μm (inset). (b) Tomographic image of boxed area in (a). Note that the plasma membrane lacks deep grooves at section. Scale bar, 1 μm. M, mitochondrion; P, plastid; V, vacuole; W, cell wall. (c–g) 3D images showing distribution of plasma membrane (magenta), and underlying flattened vesicles (yellow) associated with microtubules (green) on cytoplasmic side. Not to scale. Note that plasma membrane and flattened vesicles exhibit almost smooth surfaces. Arrowheads indicate slight overlapping of neighbouring flattened vesicles. (c) View with a tomographic image. For abbreviations of organelles, see (b). (d,e) View from the cell wall side. (f,g) View from the cytoplasmic side.
Mentions: Using UHVEM tomography, the 3D ultrastructural features of the plasma membrane and the flattened vesicles at the protoplast periphery of the two Glaucocystis species were visualised with high contrast (Figs 2 and 3 and Supplementary Movies 1,2,3,4). In both species, the flattened vesicles were leaflet-like in shape, lacked a plate-like interior structure, and were distributed throughout the entire protoplast periphery just underneath the single-layered plasma membrane (except for the region near basal bodies; see below), but did not completely enclose the protoplast periphery to form small spaces between the vesicles at the protoplast periphery.

Bottom Line: The primary phototrophs, glaucophytes, are thought to retain ancestral features of the first photosynthetic eukaryote, but examining the protoplast ultrastructure has previously been problematic in the coccoid glaucophyte Glaucocystis due to its thick cell wall.This 3D feature is essentially identical to that of another glaucophyte genus Cyanophora, as well as the secondary phototrophs in Alveolata.Thus, the common ancestor of glaucophytes and/or the first photosynthetic eukaryote may have shown similar 3D structures.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

ABSTRACT
A heterotrophic organism 1-2 billion years ago enslaved a cyanobacterium to become the first photosynthetic eukaryote, and has diverged globally. The primary phototrophs, glaucophytes, are thought to retain ancestral features of the first photosynthetic eukaryote, but examining the protoplast ultrastructure has previously been problematic in the coccoid glaucophyte Glaucocystis due to its thick cell wall. Here, we examined the three-dimensional (3D) ultrastructure in two divergent species of Glaucocystis using ultra-high voltage electron microscopy. Three-dimensional modelling of Glaucocystis cells using electron tomography clearly showed that numerous, leaflet-like flattened vesicles are distributed throughout the protoplast periphery just underneath a single-layered plasma membrane. This 3D feature is essentially identical to that of another glaucophyte genus Cyanophora, as well as the secondary phototrophs in Alveolata. Thus, the common ancestor of glaucophytes and/or the first photosynthetic eukaryote may have shown similar 3D structures.

No MeSH data available.


Related in: MedlinePlus