Characterization and gene expression profiles of Cilus gilberti leptin in response to culture parameters

Abstract

The Chilean meagre, Cilus gilberti, emerges as a novel species to South American aquaculture. Nevertheless, the successful establishment of its cultivation necessitates careful consideration of productive parameters and tolerance to abiotic stressors. To address these challenges, the identifications of biomarkers emerges as a promising approach. Indeed, leptin stands out as a potential biomarker, given its multifaceted role. This study focuses on characterizing leptin in C. gilberti (cgLep) and assessing its gene expression in juveniles exposed to different culture and feeding conditions. The results indicated that cgLep coding sequence yields a 137-amino acid prohormone, preserving high relevant cysteine residues for maintaining its structural integrity. Basal cgLep gene expression profiles reveal its expression mainly in the liver, followed by white muscle. Conversely, its receptor (cgLepR) exhibits higher levels in white muscle. Additionally, it was observed that juveniles in a postprandial state exhibited an upregulation of hepatic cgLep. Simultaneously, the cgLepR showed a significant increase at brain level during the preprandial stage. The exposure to acute hypoxia revealed a notable upregulation of cgLep after two hours of low oxygen availability and returned to normoxia baseline after six hours post-hypoxia. Notably, when subjected to a prolonged daily hypoxia regimen, no significant differences in leptin mRNA expression were observed. This suggests a dynamic adaptive response of the C. gilberti leptin system to hypoxia. Finally, juvenile Chilean meagre cultivated at 15 Kg/m3 showcase significant individual variability in hepatic leptin expression levels when compared to those cultured at 25 or 35 kg/m3. These observations highlight that leptin primarily expresses in the liver and its expression is notably influenced by fasting periods and chronic stress induced by low stock density. This variability in leptin expression could potentially impact food intake, emphasizing the importance of considering these factors in the design and implementation of aquaculture practices for Chilean meagre.