195 SPERMATOZOAL PROTEIN MARKERS FOR ANGUS BULL FERTILITY

Abstract

Fertility is one of the most economically important traits controlling animal reproduction. Despite its significant economic impact, there are no reliable markers to predict semen quality. The objective of this study was to identify spermatozoal proteins associated with bull fertility, the ability of the sperm to fertilize the oocyte and support embryonic development. To accomplish our objectives, we isolated total spermatozoal proteins from 4 Angus bulls with different fertility phenotypes. Next, differentially expressed proteins were determined using two-dimensional differential in-gel electrophoresis (2D-DIGE), followed by sequencing of the most differentially expressed proteins. Immunoblotting experiments were conducted to confirm expression of key proteins detected by 2D-DIGE. Our results from 2D-DIGE experiments showed approximately 2000 detectable spermatozoal proteins. Of these comprehensive lists of proteins, we identified 80 of the proteins with the highest differential expression in spermatozoa from high- and low-fertility bulls. Diverse sets of differentially expressed proteins known to play roles in sperm motility, metabolism, and cell morphology were identified. These proteins included outer dense fibre of sperm tails 2 and manganous superoxide, heat shock protein, tubulins, α-enolase, and acrosomal vesicle protein-1. Expression profiles of outer dense fibre of sperm tails 2 and manganous superoxide dismutase were confirmed using immunoblotting. The findings are significant because they help us understand the fundamental biology of the male gamete and early development. In addition, the identified proteins can be used as molecular markers to predict bull fertility, an economically important trait. Funded in part by the Mississippi Agricultural and Forestry Experiment Station, American Angus Association, and Alta Genetics, Inc.