Wolbachia Infection Decreased the Resistance of Drosophila to Lead

Abstract

BackgroundThe heavy metal lead has been shown to be associated with a genotoxic risk. Drosophila melanogaster is a model organism commonly utilized in genetic toxicology testing. The endosymbionts — Wolbachia are now very common in both wild populations and laboratory stocks of Drosophila. Wolbachia may induce resistance to pathogenic viruses, filarial nematodes and Plasmodium in fruit fly and mosquito hosts. However the effect of Wolbachia infection on the resistance of their hosts to heavy metal is unknown.Methodology/Principal FindingsManipulating the lead content in the diet of Drosophila melanogaster, we found that lead consumption had no different effects on developmental time between Wolbachia-infected (Dmel wMel) and –uninfected (Dmel T) flies. While in Pb-contaminated medium, significantly reduced amount of pupae and adults of Dmel wMel were emerged, and Dmel wMel adults had significantly shorter longevity than that of Dmel T flies. Lead infusion in diet resulted in significantly decreased superoxide dismutase (SOD) activity in Dmel T flies (P<0.05), but not in Dmel wMel flies. Correspondingly, lead cultures induced a 10.8 fold increase in malonaldehyde (MDA) contents in Dmel T larvae (P<0.05). While in Dmel wMel larvae, it resulted in only a 1.3 fold increase. By quantitative RT-PCR, we showed that lead infused medium caused significantly increased expression level of relish and CecA2 genes in Dmel T flies (P<0.01). Lead cultures did not change dramatically the expression of these genes in Dmel wMel flies.Conclusions/SignificanceThese results suggest that Wolbachia infection decreased the resistance of Drosophila to lead likely by limiting the production of peroxides resulted from lead, thus being unable to activate the immunological pathway in the host to prevent them from lead damage. This represents a novel Wolbachia–host interaction and provides information that researchers working on Drosophila toxicology should take in consideration the presence of Wolbachia in the stocks they are analyzing.

A recessive X‐linked mutation causes a threefold reduction of total body zinc accumulation in Drosophila melanogaster laboratory strains

“…Zinc accumulation in wild type Tan3 flies was consistent with values observed in many other Drosophila species [45]. Our first attempt to explain the new findings was to test for the presence of maternal factors that could influence metal homeostasis, such as the presence of Wolbachia endosymbionts [46–48]. However, crossing of low zinc female fbl 1 /TM6 to high/normal zinc male fbl 1 /TM3 flies and exchanging the balancers resulted in new stocks with high/normal zinc accumulation (data not shown).…”

Wolbachia and the insect immune system: what reactive oxygen species can tell us about the mechanisms of Wolbachia–host interactions

“…When D. melanogaster is challenged by a lead-contaminated diet, flies cured of infection exhibit a strongly increased malondialdehyde content, which is a marker for oxidative stress. In addition, high-lead diet significantly decreases SOD activity in cured flies, but not in infected flies ( Wang et al, 2012 ).…”

Life Extension

“…Wolbachia likely may be implicated in these associations. Wang et al (2012) demonstrated that Wolbachia infection decreased activity of SOD compared to tetracycline treated flies.…”

“…Statement about interaction of this gene with Wolbachia is rather hypothetical Gene name Model on which Wolbachia-Drosophila interactions were studied Reference Atg8a (Autophagy-related 8a) a Adult females Voronin et al (2012) chico Larval testes Zheng et al (2011) EcR (Ecdysone receptor) N/A b Negri and Pellecchia (2012) Hsp22 (Heat shock protein 22) S2 cell line Xi et al (2008) Larval testes Zheng et al (2011) Hsp26 S2 cell line Xi et al (2008) Hsp27 S2 cell line Xi et al (2008) Hsp68 S2 cell line Xi et al (2008) Hsp70 S2 cell line Xi et al (2008) Ilp (Insulin-like peptide) Adult males and females Gronke et al 2010 Indy ("I'm not dead yet") Larval testes Zheng et al (2011) Adult males Toivonen et al (2007) InR (Insulin receptor) Adult males and females Ikeya et al (2009) mld (molting defective (DTS-3) S2 cell line Xi et al (2008) mthl5 (methuselah-like 5) S2 cell line Xi et al (2008) mys (myospheroid) S2 cell line Xi et al (2008) PGRP-LE (Peptidoglycan recognition protein-LE) N/A b Kaneko et al (2006), Lemaitre and Hoffmann (2007) PGRP-LF (Peptidoglycan recognition protein LF)S2 cell lineXi et al (2008) puc (puckered) S2 cell lineXi et al (2008) Sod (Superoxide dismutase) Adult males and femalesWang et al (2012) …”