Brief exposures to conspecific-derived alarm substance are sufficient to induce paternal intergenerational effects in zebrafish

Paternal intergenerational effects, whereby the father's environment influences the phenotype of the offspring via molecular (e.g. epigenetic) changes to the sperm, comprise an area of active research in multiple biological contexts. Spermatogenesis is a critical window of sensitivity to environmental changes, such that males at full sexual maturity can acquire, incorporate, and transmit environmental information in spermatozoa. The degree of sensitivity is less clear, and as such previous experimental studies have typically relied on prolonged exposure regimes encapsulating the entire period of spermatogenesis. Here we exposed adult male zebrafish to a model stressor (conspecific-derived alarm substance, AS) in two 20-min episodes timed either shortly before or during the onset of spermatogenesis. There was no clear effect of paternal stress on a behavioural stress response in larval offspring but clear reductions in anxiety-like behaviour in juvenile offspring. Our findings suggest that prolonged exposures may not be required for the induction of measurable intergenerational responses in this popular vertebrate model.