Biology subjects

Gottlieb, Y.

Publications and source records attributed to Gottlieb, Y..

3 recordsLinked to original sources

bioRxiv2024

Warm temperature inhibits cytoplasmic incompatibility induced by endosymbiotic Rickettsiella in a spider host

Bacterial endosymbionts manipulate reproduction in arthropods to increase prevalence in the host population. One such manipulation is cytoplasmic incompatibility (CI), wherein the bacteria sabotage sperm in infected males to reduce hatch rate when mated with uninfected females, but zygotes are "rescued" when that male mates with an infected female. In the spider Mermessus fradeorum (Linyphiidae), Rickettsiella symbionts cause variable levels of CI. We hypothesized that temperature affects CI strength and rescue in M. fradeorum, potentially mediated by bacterial titer. We reared Rickettsiella-infected spiders in two temperature conditions (26{degrees}C vs 20{degrees}C) and tested CI induction in males and CI rescue in females. In incompatible crosses between infected males and uninfected females, hatch rate from warm males was doubled (Mean{+/-}S.E. = 0.687{+/-}0.052) relative to cool males (0.348{+/-}0.046), indicating that CI induction is weaker in warm males. In rescue crosses between infected females and infected males, female rearing temperature had a marginal effect on CI rescue, but hatch rate remained high for both warm (0.960{+/-}0.023) and cool females (0.994{+/-}0.004). Bacterial titer as measured by qPCR was lower in warm than cool spiders, particularly in females, suggesting that bacterial titer may play a role in causing the temperature-mediated changes in CI.

ecology↗

bioRxiv2022

Genomic Changes During the Evolution of the Coxiella Genus Along the Parasitism-Mutualism Continuum.

The Coxiellaceae family is composed of five genera showing lifestyles ranging from free-living to symbiosis. Among them, Coxiella burnetii is a well-known pathogen causing Q fever in humans. This bacterium presents both intracellular (parasitic) and environmental (resistant) forms. Recently, several environmental Coxiella genomes have been reported, among which several have come from intracellular mutualistic symbionts of ticks, termed Coxiella-like endosymbionts. We sequenced two new Coxiella-LE genomes from Dermacentor marginatus (CLEDm) and Ornithodoros maritimus (CLEOmar) ticks, the latter belonging to the C. burnetii lineage. Using these newly sequenced Coxiella-LEs and 43 Coxiellaceae genomes, we conducted comparative genomic and phylogenomic analyses to increase our knowledge of C. burnetii pathogenicity and the emergence of Coxiella-LEs. Results highlight the probably parasitic nature of the common ancestor of the Coxiellaceae. Indeed, the virulence factor Dot/Icm T4 Secretion System is present in most, but not all, Coxiellaceae. Whereas it is part of a putative pathogenic island in C. burnetii, it has been entirely lost or inactivated in Coxiella-LEs, suggesting its importance in pathogenesis. Additionally, we found that a Sha/Mrp antiporter was laterally acquired in the C. burnetii lineage. This antiporter might be involved in alkali resistance and the development of the resistant form that is able to persist in the environment for long periods of time. The Sha operon is eroded or absent in Coxiella-LEs. Finally, we found that all Coxiella representatives produce B vitamins and co-factors indicating a pre-adaptation of Coxiella to mutualism with hematophagous arthropods. Accordingly, the ancestor of C. burnetii and Coxiella-LEs was likely a parasitic bacterium able to manipulate its host cell and to produce vitamins and co-factors for its own use.

microbiology↗

bioRxiv2021

A dual endosymbiosis drives nutritional adaptation to hematophagy in the invasive tick Hyalomma marginatum

Many animals are dependent on microbial partners that provide essential nutrients lacking from their diet. Ticks, whose diet consists exclusively on vertebrate blood, rely on maternally inherited bacterial symbionts to supply B vitamins. While previously studied tick species consistently harbor a single lineage of those nutritional symbionts, we evidence here that the invasive tick Hyalomma marginatum harbors a unique dual-partner nutritional system between an ancestral symbiont, Francisella, and a more recently acquired symbiont, Midichloria. Using metagenomics, we show that Francisella exhibits extensive genome erosion that endangers the nutritional symbiotic interactions: Its genome includes folate and riboflavin biosynthesis pathways but deprived functional biotin biosynthesis on account of massive pseudogenization. Co-symbiosis compensates this deficiency since the Midichloria genome encompasses an intact biotin operon, which was primarily acquired via lateral gene transfer from unrelated intracellular bacteria commonly infecting arthropods. Thus, in H. marginatum, a mosaic of co-evolved symbionts incorporating gene combinations of distant phylogenetic origins emerged to prevent the collapse of an ancestral nutritional symbiosis. Such dual endosymbiosis was never reported in other blood feeders but was recently documented in agricultural pests feeding on plant sap, suggesting that it may be a key mechanism for advanced adaptation of arthropods to specialized diets.

evolutionary biology↗