A new type of 3-D peripheral ultrastructure in Glaucocystis (Glaucocystales, Glaucophyta) as revealed by ultra-high voltage electron microscopy.
The coccoid glaucophyte genus Glaucocystis is characterized by having a thick cell wall, which has to date prohibited examination of the native ultrastructural features of the protoplast periphery. Recently, however, the three-dimensional (3-D) ultrastructure of the protoplast periphery was revealed in two divergent Glaucocystis species, with the world's most powerful ultra-high voltage electron microscope (UHVEM). The two species exhibit morphological diversity in terms of their 3-D ultrastructural features. However, these two types do not seem to encompass actual ultrastructural diversity in the genetically diverse genus Glaucocystis. Here, we report a new type of peripheral 3-D ultrastructure resolved in "G. incrassata" SAG 229-2 cells by 3-D modeling based on UHVEM tomography using high-pressure freezing and freeze-substitution fixation. The plasma membrane and underlying flattened vesicles in "G. incrassata" SAG 229-2 exhibited grooves at intervals of 200-600 nm, and the flattened vesicles often overlapped one another at the protoplast periphery. This 3-D ultrastructure differs from those of the two types previously reported in other species of Glaucocystis. The possibility of classification of Glaucocystis species based on the 3-D ultrastructure of the protoplast periphery is discussed.
Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Toshiyuki
T
Takahashi
Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan.
Tomoki
T
Nishida
Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Chieko
C
Saito
Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan.
Hidehiro
H
Yasuda
Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Hisayoshi
H
Nozaki
D017110:Freeze Substitution; D005615:Freezing; D058108:Glaucophyta / Q000145:classification / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D011523:Protoplasts / Q000648:ultrastructure*; D014054:Tomography
Glaucocystis; diversity; morphology; tomography; ultra-high voltage electron microscopy; ultrastructure; “Glaucocystis incrassata” SAG 229-2