RRC ID 32137
Author Kawafune K, Sato M, Toyooka K, Nozaki H.
Title Ultrastructure of the rickettsial endosymbiont "MIDORIKO" in the green alga Carteria cerasiformis as revealed by high-pressure freezing and freeze-substitution fixation.
Journal Protoplasma
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.
Volume 250(4)
Pages 949-53
Published 2013-8
DOI 10.1007/s00709-012-0469-4
PMID 23178999
MeSH Cell Membrane / chemistry Cell Membrane / ultrastructure Cell Wall / chemistry Cell Wall / ultrastructure Chlorophyta / microbiology* Chlorophyta / ultrastructure* Freeze Substitution / methods* Rickettsiaceae / chemistry Rickettsiaceae / ultrastructure* Symbiosis Tissue Fixation / methods Tissue Preservation / methods
IF 2.457
Times Cited 5
Algae NIES-424 NIES-426