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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 of the cell periphery near basal bodies of “Glaucocystis geitleri” SAG 229-1 (a–c) and G. nostochinearum SAG 16.98 (d–f). Corresponding to Supplementary Movies 5 and 6. (a,d) Ultra-high voltage electron microscopic images of vegetative cells. Insets show higher magnification images in boxed area. Scale bar, 5 μm and 500 nm (insets). (b,c,e,f) Tomographic images of boxed area in (a,d), showing portions of cell periphery near basal bodies and vestigial flagella. Shown at the same magnification. Note that the cell periphery in these areas is composed of plasma membrane (asterisks) and ovoid-to-spherical vesicles surrounding basal bodies. Scale bar, 500 nm. B, basal body; F, vestigial flagellum; N, nucleus; O, ovoid-to-spherical vesicle; P, plastid; T, microtubule; W, cell wall.
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f4: Electron tomography of the cell periphery near basal bodies of “Glaucocystis geitleri” SAG 229-1 (a–c) and G. nostochinearum SAG 16.98 (d–f). Corresponding to Supplementary Movies 5 and 6. (a,d) Ultra-high voltage electron microscopic images of vegetative cells. Insets show higher magnification images in boxed area. Scale bar, 5 μm and 500 nm (insets). (b,c,e,f) Tomographic images of boxed area in (a,d), showing portions of cell periphery near basal bodies and vestigial flagella. Shown at the same magnification. Note that the cell periphery in these areas is composed of plasma membrane (asterisks) and ovoid-to-spherical vesicles surrounding basal bodies. Scale bar, 500 nm. B, basal body; F, vestigial flagellum; N, nucleus; O, ovoid-to-spherical vesicle; P, plastid; T, microtubule; W, cell wall.

Mentions: Although vestigial flagella in Glaucocystis cells have previously been observed by ultrathin section TEM23242526, our UHVEM tomography clearly showed the 3D ultrastructure of the protoplast periphery surrounding basal bodies and neighbouring vestigial flagella in “G. geitleri” SAG 229-1 (Fig. 4a–c and Supplementary Movie 5) and G. nostochinearum SAG 16.98 (Fig. 4d–f and Supplementary Movie 6). The 3D structure of the protoplast periphery surrounding basal bodies and neighbouring vestigial flagella in the two species was essentially identical. Two vestigial flagella were situated between the cell wall and protoplast periphery at the cell equator and positioned within the furrow of the protoplast surface, and were connected to the basal bodies within the cytoplasm. Flattened vesicles were lacking near the basal bodies and flagella as observed previously24 but the present UHVEM clearly revealed ovoid-to-spherical vesicles distributed below the plasma membrane near the basal bodies and flagella (Fig. 4 and Supplementary Movies 5 and 6).


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 of the cell periphery near basal bodies of “Glaucocystis geitleri” SAG 229-1 (a–c) and G. nostochinearum SAG 16.98 (d–f). Corresponding to Supplementary Movies 5 and 6. (a,d) Ultra-high voltage electron microscopic images of vegetative cells. Insets show higher magnification images in boxed area. Scale bar, 5 μm and 500 nm (insets). (b,c,e,f) Tomographic images of boxed area in (a,d), showing portions of cell periphery near basal bodies and vestigial flagella. Shown at the same magnification. Note that the cell periphery in these areas is composed of plasma membrane (asterisks) and ovoid-to-spherical vesicles surrounding basal bodies. Scale bar, 500 nm. B, basal body; F, vestigial flagellum; N, nucleus; O, ovoid-to-spherical vesicle; P, plastid; T, microtubule; W, cell wall.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Electron tomography of the cell periphery near basal bodies of “Glaucocystis geitleri” SAG 229-1 (a–c) and G. nostochinearum SAG 16.98 (d–f). Corresponding to Supplementary Movies 5 and 6. (a,d) Ultra-high voltage electron microscopic images of vegetative cells. Insets show higher magnification images in boxed area. Scale bar, 5 μm and 500 nm (insets). (b,c,e,f) Tomographic images of boxed area in (a,d), showing portions of cell periphery near basal bodies and vestigial flagella. Shown at the same magnification. Note that the cell periphery in these areas is composed of plasma membrane (asterisks) and ovoid-to-spherical vesicles surrounding basal bodies. Scale bar, 500 nm. B, basal body; F, vestigial flagellum; N, nucleus; O, ovoid-to-spherical vesicle; P, plastid; T, microtubule; W, cell wall.
Mentions: Although vestigial flagella in Glaucocystis cells have previously been observed by ultrathin section TEM23242526, our UHVEM tomography clearly showed the 3D ultrastructure of the protoplast periphery surrounding basal bodies and neighbouring vestigial flagella in “G. geitleri” SAG 229-1 (Fig. 4a–c and Supplementary Movie 5) and G. nostochinearum SAG 16.98 (Fig. 4d–f and Supplementary Movie 6). The 3D structure of the protoplast periphery surrounding basal bodies and neighbouring vestigial flagella in the two species was essentially identical. Two vestigial flagella were situated between the cell wall and protoplast periphery at the cell equator and positioned within the furrow of the protoplast surface, and were connected to the basal bodies within the cytoplasm. Flattened vesicles were lacking near the basal bodies and flagella as observed previously24 but the present UHVEM clearly revealed ovoid-to-spherical vesicles distributed below the plasma membrane near the basal bodies and flagella (Fig. 4 and Supplementary Movies 5 and 6).

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