Fig. 6

Expression of ammonia, sulphide, and carbon monoxide detoxification pathways in the gills of wild crabs. a Taxonomic assignment of bacteria transcripts assembled from gill tissue metatranscriptomes (CI_1–CI_4) of the fiddler crab C. inversa collected from the Red Sea coast near KAUST (related to KSA samples). Bar plots show the relative proportion of total transcripts assigned to prokaryotes (details in the “Methods”) in four independent animals. b Normalised mean expression (as RPKM values log-scaled) of key enzymes involved in nitrogen (AMT, GDH, and GS), sulphur (soxC and SQR), and carbon (cutL) metabolism, most of which are derived from Actinobacteria in the case of C. inversa. Gene abbreviations (and corresponding KO identifiers): AMT, ammonia transporter (K03320); GDH, glutamate dehydrogenase (K15371); GS, glutamine synthetase (K01915); soxC, sulphite oxidase (K00387); SQR, sulphide:quinone oxidoreductase (K17218); and cutL, aerobic carbon monoxide dehydrogenase, large subunit (K03520). No psrA, polysulfide reductase subunit A (K08352), was detected. RPKM (reads per kilobase per million mapped reads) denotes normalised expression levels. The red stack of the bar plot represents Actinobacteria and the black stack of all the other bacterial phyla