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    Advances in cryopreservation of bull sperm
    (FRONTIERS MEDIA SA, 2019) Uğur, Muhammet Raşit; Abdelrahman, Amal Saber; Evans, Holly C.; Gilmore, Alicia A.; Hitit, Mustafa; Arifiantini, Raden Iis; Purwantara, Bambang; Kaya, Abdullah; Memili, Erdoğan
    Cryopreservation of semen and artificial insemination have an important, positive impact on cattle production, and product quality. Through the use of cryopreserved semen and artificial insemination, sperm from the best breeding bulls can be used to inseminate thousands of cows around the world. Although cryopreservation of bull sperm has advanced beyond that of other species, there are still major gaps in the knowledge and technology bases. Post-thaw viability of sperm is still low and differs significantly among the breeding bulls. These weaknesses are important because they are preventing advances both in fundamental science of mammalian gametes and reproductive biotechnology. Various extenders have been developed and supplemented with chemicals to reduce cryodamage or oxidative stress with varying levels of success. More detailed insights on sperm morphology and function have been uncovered through application of advanced tools in modern molecular and cell biology. This article provides a concise review of progress in the cryopreservation of bull sperm, advances in extender development, and frontiers using diverse techniques of the study of sperm viability. This scientific resource is important in animal biotechnology because with the advances in discovery of sperm fertility markers, there is an urgent need to improve post-thaw viability and fertility of sperm through enhanced cryopreservation for precision agriculture to produce food animals to ensure food security on the global scale.
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    Sperm cellular and nuclear dynamics associated with bull fertility
    (Elsevier B.V., 2019) Kutchy, Naseer A.; Menezes, Erica S.B.; Uğur, Muhammet R.; Ul Husna, Asma; ElDebaky, Hazem; Evans, Holly C.; Beaty, Emilly; Santos, Fagner C.; Tan, Wei; Wills, Robert W.; Topper, Einko; Kaya, Abdullah; Moura, Arlindo A.; Memili, Erdoğan
    The objective of this study was to ascertain cellular characteristics and the dynamics of the sperm chromatin proteins protamine 1 (PRM1) and protamine 2 (PRM2) in the sperm of Holstein bulls having a different fertility status. Important sperm variables were analyzed using computer-assisted sperm analysis (CASA). Sperm membrane, acrosome status, DNA integrity were also assessed using propidium iodide (PI), fluorescein isothiocyanate conjugated to Arachis hypogaea (FITC-PNA), and acridine orange (AO) followed by flow cytometry. In addition, abundances of PRM1 and PRM2 were analyzed using flow cytometry experiments. Differences in sperm decondensation capacity were assessed in bulls of varying fertility using a decondensation assay. As determined using CASA, average pathway velocity, amplitude of lateral head displacement and straightness were different (P < 0.05) for sperm from high and low fertility bulls. There, however, were no differences between the high and low fertility bulls for characteristics of sperm plasma membrane, acrosome, and DNA integrity (P > 0.05). Relative abundances of PRM1 and PRM2 in sperm from the high and low fertility bulls were inversely related (P < 0.0001). Percentages of decondensed sperm were different between high and low fertility bulls (P < 0.0001) and total numbers of decondensed sperm were greater in low fertility bulls than high fertility bulls (R2 = 0.72). Results of the present study are significant because molecular and morphological phenotypes of sperm that were detected affect fertility in livestock species.