Original Contributions to the Theory of Epigenetic Inheritance in Response to Nutritional Stress in Farmed Clarias gariepinus Populations

Epigenetic mechanisms, including DNA methylation and histone modification, are increasingly recognised as determinants of phenotypic plasticity and adaptive responses in farmed fish populations, yet no research has investigated the epigenetic consequences of nutritional stress and their potential transgenerational inheritance in African catfish populations in Nigeria. This study makes original theoretical and empirical contributions to understanding epigenetic inheritance in response to nutritional stress in Clarias gariepinus populations bred at the National Institute for Freshwater Fisheries Research, Niger State. F0 broodstock were subjected to chronic protein restriction (50% of optimal protein intake) or control feeding over one full reproductive cycle. F1 offspring from both groups were reared under identical optimal nutritional conditions. Growth performance, feed utilisation, muscle tissue proximate composition, and global DNA methylation levels (measured by ELISA and bisulphite sequencing of candidate gene promoters) were compared between F1 offspring of stressed and control F0 parents. Results showed that F1 offspring of nutritionally stressed parents exhibited persistently lower growth rates and altered muscle fatty acid profiles compared to F1 control offspring despite receiving identical nutrition from hatching, consistent with transgenerational epigenetic inheritance. Global DNA methylation was 23% higher in muscle tissue of F1 offspring from stressed parents. Bisulphite sequencing identified differential methylation at promoters of three growth-related genes, including igf-1 and myosin heavy chain, between the two F1 groups. The study establishes the first evidence of transgenerational epigenetic inheritance in African catfish and proposes an original theoretical model for nutritional programming effects in farmed catfish populations with implications for broodstock management.

Keywords: epigenetic inheritance, DNA methylation, nutritional stress, Clarias gariepinus, transgenerational effects