Light regimes differentially affect baseline transcript abundance of stress-axis and (neuro)development-related genes in zebrafish (, Hamilton 1822) AB and TL larvae.

Many strains of zebrafish () are readily available. Earlier we observed differences between AB and Tupfel long-fin (TL) larvae regarding baseline hypothalamus-pituitary-interrenal (HPI) axis activity and (neuro)development. Light regimes, i.e. 14 h light:10 h dark and 24 h continuous dark or light, affect hatching rate and larval growth. Here, we assessed baseline transcript abundance of HPI-axis-related genes and (neuro)development-related genes of AB and TL larvae (5 days post fertilisation) using these light regimes. A principal component analysis revealed that in AB larvae the baseline expression of HPI-axis-related genes was higher the more hours of light, while the expression of (neuro)development-related genes was higher under 14 h light:10 h dark than under both continuous light or dark. In TL larvae, a complex pattern emerged regarding baseline expression of HPI-axis-related and (neuro)development-related genes. These data extend data of earlier studies by showing that light regimes affect gene-expression in larvae, and more importantly so, strengthen the notion of differences between larvae of the AB and TL strain. The latter finding adds to the growing database of phenotypical differences between zebrafish of the AB and TL strain.