Format

Send to

Choose Destination
See comment in PubMed Commons below
Protoplasma. 2013 Aug;250(4):949-53. doi: 10.1007/s00709-012-0469-4. Epub 2012 Nov 23.

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

Author information

1
Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. kawafune@biol.s.u-tokyo.ac.jp

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.

PMID:
23178999
DOI:
10.1007/s00709-012-0469-4
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Springer
    Loading ...
    Support Center