Molecular Regulation of Sperm Function, Environmental Interactions, and Diagnostic Biomarkers: An Integrated Omics Approach to Understanding Sperm Performance in Important Aquaculture Species

Abstract

Reproduction is a critical component of both the economic viability and sustainability of aquaculture species. Technologies that optimize broodstock management and improve access to high-quality gametes can enhance productivity while reducing environmental impact. Emerging molecular tools provide powerful approaches for assessing sexual maturation and improving offspring production in aquaculture systems. The primary objective of this thesis was to utilize transcriptomic approaches to evaluate the quality of male gametes for major U.S. aquaculture species. The first study assessed the molecular regulation of mRNAs by miRNAs in oysters with sperm of differing qualities and cryotolerance. Our findings revealed differentially expressed RNAs and key mRNA×miRNA interactions that have roles in the regulation of oyster sperm performance. The second study investigated the role of ovarian fluid during blue catfish sperm activation to identify molecular mechanisms underlying changes in kinematic activity. Results demonstrated that the ovarian fluid microenvironment induces molecular changes in membrane properties, ion channel activity, signaling pathways, binding proteins, and energy metabolism prior to motility activation. These molecular changes promote hyperactivation of sperm cell motility. The third study evaluated circulating miRNAs as non-lethal biomarkers of sperm quality in blue catfish. Three differentially expressed miRNAs were identified between males with low-quality and high-quality sperm, highlighting their potential as diagnostic indicators. Together, these findings demonstrate the applications of reproductive molecular tools to improve industry efficiency, and sustainability in aquaculture production.