Sex matters: Gamete-specific contribution of microRNA following parental exposure to hypoxia in zebrafish.

Oxygen availability varies among aquatic environments, and oxygen concentration has been demonstrated to drive behavioral, metabolic, and genetic adaptations in numerous aquatic species. MicroRNAs (miRNAs) are epigenetic modulators that act at the interface of the environment and the transcriptome and are known to drive plastic responses following environmental stressors. An area of miRNA that has remained underexplored is the sex specific action of miRNAs following hypoxia exposure and its effects as gene expression regulator in fishes. This study aimed to identify differences in mRNA and miRNA expression in the F generation of zebrafish (Danio rerio) at 1 hpf after either F parental male or female were exposed to 2 weeks of continuous (45 %) hypoxia. In general, F embryos at 1 hpf demonstrated differences in mRNA and miRNAs expression related to the stressor and to the specific sex of the F that was exposed to hypoxia. Bioinformatic pathway analysis of predicted miRNA:mRNA relationships indicated responses in known hypoxia signaling and mitochondrial bioenergetic pathways. This research demonstrates the importance of examining the specific male and female contributions to phenotypic variation in subsequent generations and provides evidence that there is both maternal and paternal contribution of miRNA through eggs and sperm.