Expression of defensin paralogs across house fly life history: insights into fly-microbe interactions

Authors: Nayduch, Dana

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/4/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: No Interpretive Summary required for meeting abstracts.

Technical Abstract: House flies have a life-long association with microbe-rich environments. Larvae directly ingest bacteria in decaying substrates utilizing them for nutritional purposes. Adult house flies ephemerally associate with microbes, ingesting them either by direct feeding or indirectly during grooming. The house fly gut is protected from ingested bacteria by physical exclusion (e.g., the peritrophic matrix), digestive processes, and innate immune effectors such as antimicrobial peptides (AMPs). The house fly genome revealed extensive duplications and expansions of AMP families including the attacins, defensins and cecropins. Defensins are cysteine-rich microbicidal AMPs with broad-spectrum activity in the higher Diptera. We examined the differential expression of 9 defensin paralogs across life history (egg, three larval instars, pupa, adult) using qRTPCR. Patterns of defensin expression suggest utilization of some paralogs as typical immune defense components (i.e., the “ancestral” function of AMPs) and others as more digestive function, being induced when bacteria are present in the gut. Maximum likelihood analyses comparing the nonsynonymous and synonymous substitution rates between the two groups of defensins suggests that positive selection drove the diversification of novel digestive functions in 4 and possibly 5 of the duplicated genes.