Social stress in fathers affects sperm small RNA and offspring transcriptome profiles

Environmental changes may affect paternal condition and following generations but the underlying mechanisms are poorly understood. Male-male competition induces a physiological stress response and affects male hormone levels, ejaculate traits and development in their offspring. Here we investigated the role of sperm-mediated small RNAs in the transmission of male condition to the next generation. We exposed male zebrafish Danio rerio to high and low male-male competition environments for two weeks and collected sperm samples at the end. We also performed IVFs using a split-clutch design to distinguish between paternal and maternal effects and collected embryos at 24 hours to test for differentially expressed genes and transposable elements (TE)s at this key developmental stage. We sequenced micro- (mi) and Piwi-interacting (pi)RNAs in sperm and the full transcriptome in the embryos and ran differential expression analyses. We identified differentially expressed sperm mi- and piRNAs, with the strongest effects observed in sperm of males switching from high to low competition environments. We identified 612 differentially expressed genes in the embryos. These results confirm that the social environment does not only affect males but also the molecular ecology of their sperm and the gene expression in their offspring suggesting a putative role of sRNAs. Overall design: This data deposit includes the small RNA-seq data for this research. Male zebrafish were subject to high and low social stress environments, with sperm samples collected, RNA extracted and sent for small RNA sequencing.