Sperm Genetic and Epigenetic Mechanisms Regulating Male Fertility

Male fertility, ability to fertilize and activate the egg and support early embryo development, is crucial for mammalian reproduction and development. Testis specific histone 2B (TH2B) of sperm, protamines (PRM1/2), and posttranslational modifications of histone 3 (H3K27me3 and H3k27ac) are involved in spermatogenesis and male fertility. However, molecular and cellular mechanisms by which TH2B regulates histone to protamine replacement is poorly defined. Immunocytochemistry, western blotting, flow cytometry, computer-assisted sperm analysis (CASA) and bioinformatic approaches were applied to analyze sperm from Holstein bulls with different in vivo fertility. Results from the immunocytochemistry experiments showed that while TH2B and H3K27me3 were localized predominantly at the equatorial and post acrosomal (localized as a crown around the sperm head) parts, respectively. The H3K27ac was also detectable in the bovine sperm head. Signal intensities of TH2B (mean ± SEM) were higher in sperm from the low fertility bulls (220.56 ± 9.20) as compared to those from the high fertility bulls (198.39 ± 10.0). Signal intensities of H3K27me3 (16.25 ± 1.69) were significantly different than those of H3K27ac (4.74 ± 0.88) in bull spermatozoa. Using the bioinformatic tools, including Clustal Omega, Cytoscape, Emboss Dotmatcher, InterProScan, and STRING, we demonstrated that TH2B has the conserved histone H2B domain which has a strong association with proteins involved in chromosome organization and histone ubiquitination. Intensities of PRM1 and PRM2 were significantly associated with one another (p \u3c 0.0001), but neither were significantly associated with fertility. Results from CASA revealed significant differences between high and low fertility bulls regarding average sperm pathway velocity, amplitude of lateral head displacement and straightness (p \u3c 0.05). The interacting proteins of H3 are involved in subcellular processes such as regulation of H3K27 methylation, nucleosome assembly, regulation of DNA replication, and chromatin assembly. These results are significant because they help advance fundamental knowledge in sperm physiology involving epigenetic and genetic determinants. The new knowledge can be used to enhance reproductive biotechnology to improve fertility. In addition, the data generated using the unique bull model can be applied to study mammalian reproduction and development due to similarities in genetics and physiology between bovine and other mammals

Sperm proteins ODF2 and PAWP as markers of fertility in breeding bulls

Low fertility is the single most important factor limiting livestock reproductive performance, adversely affecting the cattle industry and causing millions of dollars of economic loss. In the livestock industry, male fertility is of crucial importance for the reproductive performance of livestock. However, there is a lack of reliable biomarkers to predict bull fertility in artificial insemination service. The objective of this study was to identify sperm proteins as biomarkers for bull fertility. To discover candidate sperm quality biomarkers, sperm proteome profiling was conducted in extreme high- and extreme low-fertile bulls selected from a pool of 1000 AI sires with varied fertility. Thirty-two differentially expressed proteins were identified. Among them, high levels of sperm outer dense fiber of sperm tails 2 (ODF2) and post-acrosomal assembly of sperm head protein (PAWP/WBP2NL) represented the most extreme differences in quantity between high- and low-fertility bulls. Protein immunodetection and flow cytometry used to validate these putative fertility markers in a combined cohort of 154 AI sires. Both ODF2 and PAWP correlated significantly with fertility. In conclusion, ODF2 and PAWP can be used to assess semen quality and predict sire fertility

REVIEW: SOLUTIONS FOR GRAND CHALLENGES IN GOAT AND SHEEP PRODUCTION INDUSTRY

Goats and sheep are valuable as they are a source of meat, milk, fleece, and other products. These livestock are also important both for agriculture and biomedical research. However, the efficient, sustainable, and profitable production of these small ruminants faces major obstacles. Hence, this review analyzes these major challenges specifically, their negative impacts on the industry, and suggests some science-based solutions to overcome them. Those challenged areas are education and training, research, translational research/biotechnology, goat and sheep health, and maintenance of an economically sustainable agribusiness. The suggested solutions include the effective teaching of goat and sheep science to the next generation and public empowerment, support for innovative and translational research, disease prevention and treatment, support for technology transfer, and development of sound agribusiness practices. This review is helpful particularly for scientists, students, and the goat and sheep producers. In general, these information on the current state of goat and sheep agriculture will also help the public to better understand and appreciate the challenges met and opportunities provided in small ruminant production enterprises