論文 - 詳細
| RRC ID | 20887 |
|---|---|
| 著者 | Kawafune K, Hongoh Y, Hamaji T, Nozaki H. |
| タイトル | Molecular identification of rickettsial endosymbionts in the non-phagotrophic volvocalean green algae. |
| ジャーナル | PLoS One |
| Abstract |
BACKGROUND:The order Rickettsiales comprises gram-negative obligate intracellular bacteria (also called rickettsias) that are mainly associated with arthropod hosts. This group is medically important because it contains human-pathogenic species that cause dangerous diseases. Until now, there has been no report of non-phagotrophic photosynthetic eukaryotes, such as green plants, harboring rickettsias. METHODOLOGY/PRINCIPAL FINDINGS:We examined the bacterial endosymbionts of two freshwater volvocalean green algae: unicellular Carteria cerasiformis and colonial Pleodorina japonica. Epifluorescence microscopy using 4'-6-deamidino-2-phenylindole staining revealed the presence of endosymbionts in all C. cerasiformis NIES-425 cells, and demonstrated a positive correlation between host cell size and the number of endosymbionts. Strains both containing and lacking endosymbionts of C. cerasiformis (NIES-425 and NIES-424) showed a >10-fold increase in cell number and typical sigmoid growth curves over 192 h. A phylogenetic analysis of 16 S ribosomal (r)RNA gene sequences from the endosymbionts of C. cerasiformis and P. japonica demonstrated that they formed a robust clade (hydra group) with endosymbionts of various non-arthropod hosts within the family Rickettsiaceae. There were significantly fewer differences in the 16 S rRNA sequences of the rickettsiacean endosymbionts between C. cerasiformis and P. japonica than in the chloroplast 16 S rRNA or 18 S rRNA of the host volvocalean cells. Fluorescence in situ hybridization demonstrated the existence of the rickettsiacean endosymbionts in the cytoplasm of two volvocalean species. CONCLUSIONS/SIGNIFICANCE:The rickettsiacean endosymbionts are likely not harmful to their volvocalean hosts and may have been recently transmitted from other non-arthropod organisms. Because rickettsias are the closest relatives of mitochondria, incipient stages of mitochondrial endosymbiosis may be deduced using both strains with and without C. cerasiformis endosymbionts. |
| 巻・号 | 7(2) |
| ページ | e31749 |
| 公開日 | 2012-1-1 |
| DOI | 10.1371/journal.pone.0031749 |
| PII | PONE-D-11-22754 |
| PMID | 22363720 |
| PMC | PMC3283676 |
| MeSH | Base Sequence Cell Size Chlorophyta / cytology Chlorophyta / growth & development Chlorophyta / microbiology* Host-Pathogen Interactions Humans In Situ Hybridization, Fluorescence Indoles / metabolism Molecular Sequence Data Nucleotides / genetics Phylogeny RNA, Ribosomal, 16S / genetics Rickettsiaceae / genetics* Species Specificity Staining and Labeling Symbiosis / genetics* |
| IF | 2.74 |
| 引用数 | 22 |
| WOS 分野 | MICROBIOLOGY |
| リソース情報 | |
| 藻類 | NIES-425 NIES-577 |