Spiroplasma as a model insect endosymbiont

Abstract

Members of the genus Spiroplasma are actively motile and helical bacteria of the class Mollicutes, which are associated with a variety of arthropods and plants. Some spiroplasmas cause female-biased sex ratios of their host insects as a result of selective death of the male offspring during embryogenesis. Several strains of male-killing spiroplasmas have been successfully transfected into Drosophila melanogaster by haemolymph injection and maintained in laboratory fly stocks. Spiroplasma-Drosophila endosymbiosis represents an ideal model system for analysing the molecular mechanisms underlying host-symbiont interactions. The infection dynamics exhibited by the symbiont within the host, the effects of external and environmental factors on the symbiotic association and symbiont interactions with the host's immune system have been investigated using this system. Comparisons between a male-killing Spiroplasma strain and its non-male-killing variant revealed that, in addition to different male-killing abilities, they also differed in infection dynamics and resistance to host innate immunity. It is currently unclear whether these different phenotypes are interconnected to each other. However, if so, such pleiotropy could facilitate our understanding of the genetic and molecular mechanisms of the endosymbiotic system.

Winding paths to simplicity: genome evolution in facultative insect symbionts

“…2006). These features, together with the feasibility of using Drosophila as a host, make Spiroplasma a promising system for investigating the molecular mechanisms of insect–symbiont interactions (Haselkorn, Markow and Moran 2009; Anbutsu and Fukatsu 2011; Herren et al. 2013; Harumoto, Anbutsu and Fukatsu 2014).…”

A ribosome-inactivating protein in a Drosophila defensive symbiont

“…or mutualistic (22). Maternal transmission has arisen numerous times in Spiroplasma, including strains that are well known as male-killers (22).…”

“…Maternal transmission has arisen numerous times in Spiroplasma, including strains that are well known as male-killers (22). In addition to defense against nematodes in D. neotestacea, other strains of Spiroplasma have recently been shown to protect flies and aphids against parasitic wasps and pathogenic fungi, respectively (23)(24)(25), but in no case is the mechanism of defense understood.…”

Sustainable farming of the mealworm Tenebrio molitor for the production of food and feed

“…A third study confirmed the dominance of Tenericutes (36.6%), Proteobacteria (34.1%), and Firmicutes (26.2%), and at the genus level also Spiroplasma (38.7%) [53]. Members of the genus Spiroplasma are small, helical, motile and wall-less bacteria [54]. These species promote male-killing to yield extreme female-biased sex ratios in insects and can also cause diseases in mammals, including humans [55][56][57][58].…”