Evaluation of two extant population sources of Clarias macrocephalus using liver transcriptomic profiles towards reintroduction

Abstract

There is a need to evaluate and choose a possible population source of the threatened catfish Clarias macrocephalus for possible reintroduction into aquaculture. Identifying gene transcription profiles that provide fitness benefits in specific environments would promote more effective species reintroduction and conservation practices. In this study, comparison of hepatic transcriptome profiles was made in terms of expression patterns of various growth-, immune- and reproduction-related genes of two Clarias macrocephalus strains from Cagayan (CmC) and Agusan del Sur (CmA), located in the Northern and Southern Philippines, respectively. RNA sequencing results showed that there were 13,138 differentially expressed genes (DEGs) identified in CmA vs. CmC, of which 6,795 DEGs exhibited significant upregulation while 6,343 DEGs displayed significant downregulation. From this pool of DEGs, numerous immune- (complements C3, C4, C7), growth- (glutamine synthetase, GLUL; glycogen synthase, GYS; elongation of very long chain fatty acids protein 6, ELOVL6, lipoprotein lipase, LPL) and reproduction-related (vitellogenin, VTG; cytochrome p450 19b-like, CYP19b; progesterone receptor, PGR) genes were identified. Pathway enrichment analysis revealed the enrichment of the complement component and coagulation cascades, protein digestion and absorption and lipid metabolism pathways. Results of this study indicated that when reintroduction was to be done, C. macrocephalus population from Agusan Marsh is predicted to grow much faster because of up-regulated growth-related genes, to be more resistant to pathogens/environmental stressor as it manifested up-regulated immune-related genes and to reproduce better as reflected by its up-regulated reproduction-related genes than its counterpart catfish from Cagayan.