While the importance of maternal effects has long been appreciated, a growing body
of evidence now points to the paternal environment having an important influence
on offspring phenotype. Indeed, research on rodent models suggests that paternal
stress leaves an imprint on the behaviour and physiology of offspring via nonge netic information carried in the spermatozoa; however, fish have been understudied
with regard to these sperm-mediated effects. Here, we investigated whether the ze brafish was subjected to heritable influences of paternal stress by exposing males to
stressors (conspecific-derived alarm cue, chasing and bright light) before mating and
assessing the behavioural and endocrine responses of their offspring, including their
behavioural response to conspecific-derived alarm cue. We found that after males are
exposed to stress, their larval offspring show weakened responses to stressors. Small
RNA sequencing subsequently revealed that the levels of several small noncoding
RNAs, including microRNAs, PIWI-interacting RNAs and tRNA-derived small RNAs,
were altered in the spermatozoa of stressed fathers, suggesting that stress-induced
alterations to the spermatozoal RNA landscape may contribute to shaping offspring
phenotype. The work demonstrates that paternal stress should not be overlooked as
a source of phenotypic variation and that spermatozoal small RNAs may be important
intergenerational messengers in fish