View Program - 63rd Annual Drosophila Research Conference

Living things must be able to balance their immune defenses to control potentially pathogenic microbes while also fostering beneficial ones. This is especially important when considering gut immunity. Most animals are constantly ingesting bacteria from their food and their gut immunity must be able to rid the animal of potentially harmful bacteria while maintaining beneficial bacteria. Several have shown that the humoral immune system influences the gut microbiome in Drosophila, but there has been much less investigation of the role of specific effector genotypes in shaping the microbiome and microbiome-related phenotypes. In this this study we focused on the Drosophila antimicrobial peptide Diptericin A. Diptericin A is especially important in the defense against a systemic infection by the Gram- bacteria Providencia rettgeri and the survival probability is highly dependent on the genotype of diptericin A. Diptericin A is expressed in the gut under normal rearing conditions. We tested the effect of the presence/absence and genotype of diptericin A in the gut after oral infection using gnotobiotically reared flies. We assessed the effect of mono- and poly-association with common gut bacteria including Acetobacter and Lactobacillus species as well as with P. rettgeri. We found remarkable sex-specific, microbe-specific and sex-by-microbe effects on bacterial load and fitness-related traits. Most markedly we found a mono-association with Lactobacillus plantarum greatly reduced the lifespan of female diptericin A null flies. This decrease in lifespan in diptericin A null flies was also observed in poly-associations that included L. plantarum. Surprisingly these results were not seen in male flies, lending support to the need to include both sexes in microbiome studies. Furthermore we are seeing a potential diptericin genotype effect when female flies are poly-associated with L. plantarum and A. tropicalis which is interesting in the context of there also being genotype effects after systemic infections. Overall this research characterizes the importance of having functional diptericin A in the gut for fly fitness.

Diptericin A protects flies from opportunistic gut infections in a sex dependent manner