Neurobehavioural Genes Associated With Growth in Dusky Kob (Argyrosomus japonicus)

Growth is a complex trait, influenced by numerous genes and environmental factors that transect various physiological pathways. This study sought to characterise the relationship between neurobehavioural development genes and growth in dusky kob juveniles. Five candidate neurobehavioural genes were identified from the literature and assessed for gene sequence variants. Thirteen SNPs in two genes, Brain-derived neurotrophic factor (bdnf) and Early growth response 1 (egr1), were identified. Case-control association analyses were conducted applying two methods of correcting for family structure: (1) categorical, based on family identity; and (2) quantitative, based on co-ordinate analysis eigenvalues. The eigenvalue-corrected association analysis outperformed the categorical analysis in both model adherence and estimates of effect sizes. Six significantly associated SNPs were identified, three in each gene. Linkage disequilibrium was significant within both genes, with the formation of haplotype -GA- in egr1 associated with increased growth and haplotype -CG- in bdnf associated with decreased growth. A non-synonymous mutation (Serine > Proline) was identified in bdnf, and protein modelling suggests significant disruption of protein structure in small individuals that likely explains the functional mechanism of action. This study has identified novel SNPs and haplotypes in neurobehavioural development genes, which highlight the impact of neurological and behavioural pathways on growth in dusky kob.