Flavobacteria as intracellular symbionts in cockroaches

Abstract

Animal cells are the sole habitat for a variety of bacteria. Molecular sequence data have been used to position a number of these intracellular microorganisms in the overall scheme of eubacterial evolution. Most of them have been classified as proteobacteria or chlamydiae. Here we present molecular evidence placing an intracellular symbiont among the flavobacteria-bacteroides. This microorganism inhabits specialized cells in the cockroach fat body and has been described as a mutualistic endosymbiont of uncertain phylogenetic position. The small subunit ribosomal DNA of these bacteria was analysed after polymerase chain reaction amplification to investigate their phylogeny. The endosymbionts of five species of cockroaches were found to make up a coherent group with no close relatives within the eubacterial phylum defined by the flavobacteria. In addition, the relationships among the endosymbionts, as revealed by DNA sequence data, appeared to be congruent with the host taxonomic relationships. Based on the host fossil record, a tentative calibration of the nucleotide substitution rate for the cockroach flavobacteria gave results congruent with those obtained for the aphid endosymbiotic proteobacteria.

A bacterial symbiont in theBacteroidetesinduces cytoplasmic incompatibility in the parasitoid waspEncarsia pergandiella

“…In addition to the reproductive manipulations of the CLO described here, Bacteroidetes group representatives also serve as the primary symbionts of cockroaches where they are housed in specialized cells in the fat body and appear to act as mutualists (Bandi et al 1994). Bacteroidetes symbionts have also been implicated in male killing in coccinellid beetles , and have been found as symbionts of sharpshooter insects and acanthamoebae (Horn et al 2001).…”

‘Candidatus Streptomyces philanthi’, an endosymbiotic streptomycete in the antennae of Philanthus digger wasps

“…Under the assumption of strictly vertical transmission of the symbionts, the low 16S rRNA gene sequence divergence among the endosymbionts of Philanthus wasps suggests that the symbiosis is of relatively recent origin. Assuming a mean rate of 0?008-0?02 substitutions per site per 50 million years (Bandi et al, 1994;Moran et al, 1993;Ochman & Wilson, 1987), the maximum sequence divergence of 1?07 % indicates that the origin of the symbiosis between beewolves and streptomycetes dates back about 26-67 million years.…”

Mapping the presence of Wolbachia pipientis on the phylogeny of filarial nematodes: evidence for symbiont loss during evolution

“…For all the parasite species examined, crude DNA preparations were obtained through proteinase-K treatment, according to Bandi et al (1994). For A. reconditum, DNA from a pooled sample of microfilariae obtained through blood filtration was analyzed.…”