RRC ID 56451
Author Yang A, Narechania A, Kim E.
Title Rickettsial endosymbiont in the "early-diverging" streptophyte green alga Mesostigma viride.
Journal J Phycol
Abstract A bacterial endosymbiont was unexpectedly found in the "axenic" culture strain of the streptophyte green alga Mesostigma viride (NIES-995). Phylogenetic analyses based on 16S rRNA gene sequences showed that the symbiont belongs to the order Rickettsiales, specifically to the recently designated clade "Candidatus Megaira," which is closely related to the well-known Rickettsia clade. Rickettsiales bacteria of the "Ca. Megaira" clade are found in a taxonomically diverse array of eukaryotic hosts, including chlorophycean green algae, several ciliate species, and invertebrates such as Hydra. Transmission electron microscopy, fluorescence in situ hybridi-zation, and SYBR Green I staining experiments revealed that the endosymbiont of M. viride NIES-995 is rod shaped, typically occurs in clusters, and is surrounded by a halo-like structure, presumably formed by secretory substances from the bacterium. Two additional M. viride strains (NIES-296 and NIES-475), but not SAG50-1, were found to house the rickettsial endosymbiont. Analyses of strain NIES-995 transcriptome data indicated the presence of at least 91 transcriptionally active genes of symbiont origins. These include genes for surface proteins (e.g., rOmpB) that are known to play key roles in bacterial attachment onto host eukaryotes in related Rickettsia species. The assembled M. viride transcriptome includes transcripts that code for a suite of predicted algal-derived proteins, such as Ku70, WASH, SCAR, and CDC42, which may be important in the formation of the algal-rickettsial association.
Volume 52(2)
Pages 219-29
Published 2016-4
DOI 10.1111/jpy.12385
PMID 27037587
MeSH Chlorophyta / genetics Chlorophyta / microbiology* Chlorophyta / ultrastructure In Situ Hybridization, Fluorescence Likelihood Functions Microscopy, Fluorescence Molecular Sequence Annotation Phylogeny RNA, Messenger / genetics RNA, Messenger / metabolism RNA, Ribosomal, 16S / genetics Ribosome Subunits, Small Rickettsia / physiology* Streptophyta / microbiology* Streptophyta / ultrastructure Symbiosis* Transcriptome / genetics
IF 2.831
Times Cited 10
Resource
Algae