https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:29909 P < 0.001) were found between ALDH expression and various motility parameters of stallion spermatozoa including the percentage of progressive (r = 0.79) and rapidly motile (r = 0.79) spermatozoa, whereas repeated measurements over 24 h revealed highly significant correlations among progressive motility loss, 4HNE accumulation, and ALDH expression (P ≤ 0.001). ALDH inhibition resulted in a spontaneous increase in 4HNE levels in viable cells (21.1 ± 5.8% vs. 42.6 ± 5.2%; P ≤ 0.05) and a corresponding decrease in total motility (41.7 ± 6.2% vs. 6.4 ± 2.6%; P ≤ 0.001) and progressive motility (17.0 ± 4.1% vs. 0.7 ± 0.4%; P ≤ 0.001) of stallion spermatozoa over 24 h. Similarly, inhibition of ALDH in 4HNE-challenged spermatozoa significantly reduced total motility over 4 h (35.4 ± 9.7% vs. 15.3 ± 5.1%, respectively; P ≤ 0.05). This study contributes valuable information about the role of the ALDH enzymes in the maintenance of stallion sperm functionality, with potential diagnostic and in vitro applications for assisted reproductive technologies.]]> Wed 11 Apr 2018 16:45:10 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:27633 L-tryptophan > L-tyrosine) were substrates for this enzyme, eliciting the dose- and time-dependent generation of ROS via mechanisms that were enhanced by cell death. This unexpected result was confirmed by analyses of ROS generation in subcellular sperm fractions, which again located a majority of LAAO activity to the sperm head. Equine cryopreservation medium was shown to contain sufficient quantities of aromatic amino acids to activate the LAAO system and generate ROS. The biological significance of this activity was established in an experiment in which physiological concentrations of aromatic amino acids were found to suppress sperm motility but only if dead spermatozoa were present in the same suspension. The combination of aromatic amino acids and nonviable cells was also found to enhance the levels of lipid peroxidation in live spermatozoa. These results suggest the potential significance of LAAO activity in generating the oxidative stress associated with the cryopreservation of equine spermatozoa. It is possible that inhibitors of this enzyme system may facilitate the development of modified cryostorage regimes for clinical validation in vivo.]]> Sat 24 Mar 2018 07:34:05 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:41763 p < 0.001), increased further following acrosome reaction (p < 0.01), and was localized to the equatorial region of the sperm head. Testisin was also detected in luminal fluid within the caput and corpus regions of the epididymis, epididymal spermatozoa, and epididymal epithelial cells. Testisin formed several multiprotein complexes; co‐immunoprecipitation revealed interactions of testisin with a multitude of zona pellucida‐binding proteins, including ZPBP, ZAN, acrosin, several heat‐shock proteins, and components of the TCP1 complex. Conclusion: Testisin appears to form part of the zona pellucida‐binding complex in stallion spermatozoa and may be involved in the proteolytic cascade that prepares the sperm surface for interaction with the oocyte.]]> Fri 12 Aug 2022 11:49:34 AEST ]]>