Fish skin mucus acts as a barrier between the host and environment, functioning as the first line of defence between the fish and its environment. Fish skin mucus contains beneficial proteins that are indicative of numerous biological pathways which can be leveraged in the aquaculture sector. This study characterises the skin mucus proteome of barramundi (Lates calcarifer), an important aquaculture species in Australasia. Skin mucus samples from three male and three female barramundi were processed using a lysis buffer, followed by tryptic-digest via S-Traps, and analysed with Liquid Chromatography-Tandem Mass Spectrometry (LC-MS).
A total of 1747 proteins were identified, and Gene ontology (GO) classifications using UniProt ID Mapping linked 1187 proteins to biological processes, 1384 to cellular components, and 1383 to molecular functions. Differences in protein profiles between male and female barramundi were also identified, including 98 proteins that were unique to females and 233 proteins unique to males. A differential expression analysis conducted on the 711 common proteins between the genders identified 262 significant Differentially Expressed Proteins (DEPs), with 247 upregulated proteins and 15 downregulated. Analysing the skin mucus proteins also revealed important immune related proteins such as lysozymes, complement proteins and lectins.
This study is the first to identify the proteins present in the skin mucus of barramundi. Establishing a baseline proteome of commercially important fish, such as barramundi enables the identification of pathogen induced stress proteins, disease biomarker proteins, and fertility biomarkers promoting non-invasive diagnostic approaches that eliminates an added stressor to the animal in often stressful production environments.