Identification of Molecular Biomarkers for Male Reproductive Success in Blue Catfish (Ictalurus furcatus)

Abstract

The overall objective of this project was to understand the underlying physiological and molecular processes that are associated with sperm production and function. The primary objective was to identify RNA biomarkers in the blue catfish transcriptome associated with sperm quality that may ultimately lead to increased production efficiency for hybrid catfish. In the second chapter, mature blue catfish males (n = 5) were evaluated resulting in 174 known mature miRNAs detected in both testes and sperm. All known miRNAs from sperm were detected in testes, and 5 novel miRNAs were unique to sperm, therefore showing low tissue specificity. sRNAs with differential expression were assessed, revealing that testes and sperm exhibit different expression patterns. Sperm expressed more piwi-interacting RNA (piRNA, 33bp), whereas testes expressed more miRNA (22bp). KEGG enrichment for testes and testicular sperm showed that sRNAs were primarily involved in regulating genes involved with metabolism and endocytosis. In the third chapter, 43 males were assessed for sperm velocity, a determinate of fertilization success. From these 43 males, testis tissue from 4 individuals with low velocity and 4 with high velocity were sequenced for sRNAs and mRNAs. No differentially expressed sRNAs were detected between the two performance groups, suggesting regulatory roles of sRNAs are not directly related to sperm quality in I. furcatus. However, we identified two differentially expressed mRNA transcripts between low and high velocity groups, aqp3a and ly97.3, both upregulated in the high velocity group compared to the low velocity group. Utilizing these biomarkers in the future will include laparoscopic scopes and minimally invasive surgery to screen testis tissue for ly97.3 and aqp3a expression levels in live blue catfish to predict their reproductive quality non-lethally.