Merck

Evolutionary origin of insect-Wolbachia nutritional mutualism.

Proceedings of the National Academy of Sciences of the United States of America (2014-07-02)
Naruo Nikoh, Takahiro Hosokawa, Minoru Moriyama, Kenshiro Oshima, Masahira Hattori, Takema Fukatsu
ABSTRACT

Obligate insect-bacterium nutritional mutualism is among the most sophisticated forms of symbiosis, wherein the host and the symbiont are integrated into a coherent biological entity and unable to survive without the partnership. Originally, however, such obligate symbiotic bacteria must have been derived from free-living bacteria. How highly specialized obligate mutualisms have arisen from less specialized associations is of interest. Here we address this evolutionary issue by focusing on an exceptional insect-Wolbachia nutritional mutualism. Although Wolbachia endosymbionts are ubiquitously found in diverse insects and generally regarded as facultative/parasitic associates for their insect hosts, a Wolbachia strain associated with the bedbug Cimex lectularius, designated as wCle, was shown to be essential for host's growth and reproduction via provisioning of B vitamins. We determined the 1,250,060-bp genome of wCle, which was generally similar to the genomes of insect-associated facultative Wolbachia strains, except for the presence of an operon encoding the complete biotin synthetic pathway that was acquired via lateral gene transfer presumably from a coinfecting endosymbiont Cardinium or Rickettsia. Nutritional and physiological experiments, in which wCle-infected and wCle-cured bedbugs of the same genetic background were fed on B-vitamin-manipulated blood meals via an artificial feeding system, demonstrated that wCle certainly synthesizes biotin, and the wCle-provisioned biotin significantly contributes to the host fitness. These findings strongly suggest that acquisition of a single gene cluster consisting of biotin synthesis genes underlies the bedbug-Wolbachia nutritional mutualism, uncovering an evolutionary transition from facultative symbiosis to obligate mutualism facilitated by lateral gene transfer in an endosymbiont lineage.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Biotin, meets USP testing specifications
Sigma-Aldrich
Biotin, powder, BioReagent, suitable for cell culture, suitable for insect cell culture, suitable for plant cell culture, ≥99%
Sigma-Aldrich
Biotin, tested according to Ph. Eur.
Sigma-Aldrich
Biotin, ≥99.0% (T)
USP
Biotin, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
Biotin, Vetec, reagent grade, ≥99%
SAFC
BIOTIN
Supelco
Biotin, Pharmaceutical Secondary Standard; Certified Reference Material
Biotin, European Pharmacopoeia (EP) Reference Standard
Supelco
Biotin, certified reference material, TraceCERT®