Project description:Understanding natural defence mechanisms against parasites can be a valuable tool for the development of innovative therapies. In this study, we investigated the interplay between the gill mucus metabolome and microbiome of Chaetodon lunulatus, a butterflyfish known to avoid gill monogeneans whilst living amongst closely related parasitized species. In an attempt to identify metabolites and OTUs potentially involved in parasite defence mechanisms, we studied the metabolome (LC-MS/MS) and microbiome of several sympatric butterflyfish species, including the only non-parasitized species C. lunulatus. After observing significant differences between the metabolome and microbiome of parasitized versus non-parasitized fish (PCoA, ANOSIM), we obtained the discriminant metabolites and OTUs using a supervised analysis. Some of the most important discriminant metabolites were identified as peptides, and three new β-subunit haemoblogin-derived peptides from C. lunulatus (CLHbβ-1, CLHbβ-2 and CLHbβ-3) were purified, characterised and synthesised. We also identified specific bacterial families and OTUs typical from low-oxygen habitats in C. lunulatus gill mucus. By using a correlation network between the two datasets, we found a Fusobacteriaceae strain exclusively present in C. lunulatus highly correlated to the peptides. Finally, we discuss the possible involvement of these peptides and Fusobacteriaceae in monogenean avoidance by this fish species.
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.
