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Ultrastructure of the rickettsial endosymbiont ' MIDORIKO' in the green alga Carteria cerasiformis as revealed by high-pressure freezing and freeze-substitution fixation.

Authors :
Kawafune, Kaoru
Sato, Mayuko
Toyooka, Kiminori
Nozaki, Hisayoshi
Source :
Protoplasma; Aug2013, Vol. 250 Issue 4, p949-953, 5p
Publication Year :
2013

Abstract

Bacterial endosymbionts belonging to the family Rickettsiaceae were recently identified in the unicellular green alga Carteria cerasiformis, providing the first molecular evidence of rickettsial endosymbionts within photosynthetic eukaryotes. However, previous morphological studies using transmission electron microscopy (TEM) with conventional chemical fixation did not demonstrate whether the endosymbionts of C. cerasiformis have the diagnostic characteristics of the family Rickettsiaceae. In this study, we observed the rickettsial endosymbionts ' MIDORIKO' within C. cerasiformis cells by TEM with high-pressure freezing and freeze-substitution fixation. The rickettsial endosymbionts resided directly in the C. cerasiformis cytoplasm without engulfing or encompassing membranes or vacuoles. The endosymbionts had a Gram-negative cell envelope composed of outer and inner bilayer membranes. The thicknesses of the outer and inner leaflets of the bacterial cell wall were almost identical. These morphological characteristics are consistent with those of the genus Rickettsia, but the cell wall structure differed from that of the genus Orientia within the family Rickettsiaceae. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
0033183X
Volume :
250
Issue :
4
Database :
Complementary Index
Journal :
Protoplasma
Publication Type :
Academic Journal
Accession number :
89455818
Full Text :
https://doi.org/10.1007/s00709-012-0469-4