Project description:Among the parasites of insects, endoparasitoids impose a costly challenge to host defenses because they use their host’s body for the development and maturation of their eggs or larvae, and ultimately kill the host. Tachinid flies are highly specialized acoustically-orienting parasitoids that release first instar mobile larvae which burrow into the host’s body to feed. We investigated the possibility that Teleogryllus oceanicus field crickets employ post-infestation strategies to maximize survival when infested with the larvae of the parasitoid fly Ormia ochracea. Using crickets from the Hawaiian island of Kauai, where the parasitoid is present, and crickets from the Cook Islands (Mangaia), where the parasitoid is absent, we evaluated fitness consequences of infestation by comparing feeding behavior, reproductive capacity, and survival of males experimentally infested with O. ochracea larvae. We also evaluated genetic mechanisms underlying host responses by comparing gene expression in crickets infested with fly larvae for different lengths of time with that of uninfested control crickets. We observe some differences in fitness (spermatophore production) and survival (total survival time post-infestation) between populations. However, for both traits significant population effects 1) were not associated with the slope of the response to different numbers of larvae and 2) only emerged from models containing body condition at one but not both time points evaluated. Gene expression patterns also revealed population differences in response to infestation. We did not find evidence for consistent differences in genes associated with immunity or stress response. Taken together, these results suggest that coevolution with the fly does not strongly select for either post-infestation resistance or tolerance of parasitoid larvae in male crickets.
Project description:Analyses of new genomic, transcriptomic or proteomic data commonly result in trashing many unidentified data escaping the ‘canonical’ DNA-RNA-protein scheme. Testing systematic exchanges of nucleotides over long stretches produces inversed RNA pieces (here named “swinger” RNA) differing from their template DNA. These may explain some trashed data. Here analyses of genomic, transcriptomic and proteomic data of the pathogenic Tropheryma whipplei according to canonical genomic, transcriptomic and translational 'rules' resulted in trashing 58.9% of DNA, 37.7% RNA and about 85% of mass spectra (corresponding to peptides). In the trash, we found numerous DNA/RNA fragments compatible with “swinger” polymerization. Genomic sequences covered by «swinger» DNA and RNA are 3X more frequent than expected by chance and explained 12.4 and 20.8% of the rejected DNA and RNA sequences, respectively. As for peptides, several match with “swinger” RNAs, including some chimera, translated from both regular, and «swinger» transcripts, notably for ribosomal RNAs. Congruence of DNA, RNA and peptides resulting from the same swinging process suggest that systematic nucleotide exchanges increase coding potential, and may add to evolutionary diversification of bacterial populations.