Browsing by Author "Topper E."

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Amino Acids of Seminal Plasma Associated With Freezability of Bull Sperm
(2020-01-14) Ugur M.; Dinh T.; Hitit M.; Kaya A.; Topper E.; Didion B.; Memili E.
Sperm cryopreservation is an important technique for fertility management, but post-thaw viability of sperm differs among breeding bulls. With metabolites being the end products of various metabolic pathways, the contributions of seminal plasma metabolites to sperm cryopreservation are still unknown. These gaps in the knowledge base are concerning because they prevent advances in the fundamental science of cryobiology and improvement of bull fertility. The objective of this study was to test the hypothesis that seminal plasma amino acids are associated with freezability of bull sperm. To accomplish this objective, amino acid concentrations in seminal plasma from seven bulls of good freezability (GF) and six bulls of poor freezability (PF) were quantified using gas chromatography–mass spectrometry (GC–MS). Multivariate and univariate analyses were performed to identify potential freezability biomarkers. Pathways and networks analyses of identified amino acids were performed using bioinformatic tools. By analyzing and interpreting the results we demonstrated that glutamic acid was the most abundant amino acid in bull seminal plasma with average concentration of 3,366 ± 547.3 nM, which accounts for about 53% of total amino acids. The other most predominant amino acids were alanine, glycine, and aspartic acid with the mean concentrations of 1,053 ± 187.9, 429.8 ± 57.94, and 427 ± 101.3 nM. Pearson’s correlation analysis suggested that phenylalanine concentration was significantly associated with post-thaw viability (r = 0.57, P-value = 0.043). Significant correlations were also found among other amino acids. In addition, partial least squares-discriminant analysis (PLS-DA) bi-plot indicated a distinct separation between GF and PF groups. Phenylalanine had the highest VIP score and was more abundant in the GF groups than in the PF groups. Moreover, pathway and network analysis indicated that phenylalanine contributes to oxidoreductase and antioxidant reactions. Although univariate analysis did not yield significant differences in amino acid concentration between the two groups, these findings are significant that they indicate the potentially important roles of amino acids in seminal plasma, thereby building a foundation for the fundamental science of cryobiology and reproductive biotechnology.
Cellular and Functional Physiopathology of Bull Sperm With Altered Sperm Freezability
(2020-10-23) Hitit M.; Ugur M.R.; Dinh T.T.N.; Sajeev D.; Kaya A.; Topper E.; Tan W.; Memili E.
The objective of this study was to ascertain the cellular and functional parameters as well as ROS related changes in sperm from bulls with varied sperm freezability phenotypes. Using principal component analysis (PCA), the variables were reduced to two principal components, of which PC1 explained 48% of the variance, and PC2 explained 24% of the variance, and clustered animals into two distinct groups of good freezability (GF) and poor freezability (PF). In ROS associated pathophysiology, there were more dead superoxide anion positive (Dead SO+) sperm in GF bulls than those in PF (15.72 and 12.00%; P = 0.024), and that Dead SO+ and live hydrogen positive cells (live H2O2+) were positively correlated with freezability, respectively (R2 = 0.55, P < 0.0130) and (rs = 0.63, P = 0.0498). Related to sperm functional integrity, sperm from PF bulls had greater dead intact acrosome (DIAC) than those from GF bulls (26.29 and 16.10%; P = 0.028) whereas sperm from GF bulls tended to have greater live intact acrosome (LIAC) than those from PF bulls (64.47 and 50.05%; P = 0.084). Sperm with dead reacted acrosome (DRAC) in PF bulls were greater compared to those in GF (19.27 and 11.48%; P = 0.007). While DIAC (R2 = 0.56, P = 0.0124) and DRAC (R2 = 0.57, P < 0.0111) were negatively correlated with freezability phenotype, LIAC (R2 = 0.36, P = 0.0628) was positively correlated. Protamine deficiency (PRM) was similar between sperm from GF and PF bulls (7.20 and 0.64%; P = 0.206) and (rs = 0.70, P = 0.0251) was correlated with freezability. Sperm characteristics associated with cryotolerance are important for advancing both fundamental andrology and assisted reproductive technologies across mammals.
Functional variables of bull sperm associated with cryotolerance
(2021-01-01) Gilmore A.; Hitit M.; Ugur M.R.; Dinh T.T.N.; Tan W.; Jousan D.; Nicodemus M.; Topper E.; Kaya A.; Memili E.
The objective of this study was to ascertain sperm population and cellular characteristics as well as total antioxidant capacity in spermatozoa from Holstein bulls with Good (11 bulls) and Poor (5 bulls) cryotolerance. Post-thaw sperm kinetics were evaluated using CASA, membrane integrity was assessed via HOS test, and DNA fragmentation was measured using the HaloSperm kit. Data were analyzed using principal component analysis. The spermatozoa from Good bulls had a higher number of cells with intact membranes (P=0.029), non-fragmented DNA (P=0.018), and post-thaw viability (P<0.001) compared to sperm cells from Poor cryotolerance bulls. Sperm cells from Good bulls also had a faster average path velocity (P=0.017) and straight-line velocity (P=0.036), along with a greater distance average path (P=0.006) and distance straight line (P=0.011). However, total antioxidant capacity, number of live cells, and other kinetic parameters between spermatozoa from Good and Poor groups were not different. There is no one specific sperm function variable alone that can accurately predict cryotolerance of bull spermatozoa, and thus, a combination of sperm cell attributes and kinematics needs to be utilized by the AI industry in differentiating between freezability of spermatozoa between bulls.
Lipidomic markers of sperm cryotolerance in cattle
(2020-12-01) Evans H.C.; Dinh T.T.N.; Ugur M.R.; Hitit M.; Sajeev D.; Kaya A.; Topper E.; Nicodemus M.C.; Smith G.D.; Memili E.
The objective of the current study was to determine the fatty acid composition of sperm from Holstein bulls with different freezability (Good and Poor; n = 12). Fatty acids were extracted from frozen sperm in 1:2 (v/v) chloroform–methanol solvent, fractionated into neutral and polar fractions, and composition determined by gas chromatography–mass spectrometry. Thirty-four fatty acids were quantified and their concentrations and percentages within each lipid fraction were calculated. Overall, saturated fatty acids (SFA) were predominant, accounting for 71 to 80% of fatty acids in neutral and polar lipid factions. There were marked differences in fatty acid composition between the lipid fractions (P < 0.001). The branched chain fatty acid (BCFA) concentration (15 to 18 µg) was almost twice as much as polyunsaturated fatty acids (PUFA) concentration found in the polar lipid fraction (8 to 9 µg; P < 0.001). Sperm with different freezability phenotypes only had a few differences in 22:0, 18:1 cis 9, and 14:0 13-methyl fatty acids (P ≤ 0.011). These results are significant because they reveal key understandings of fatty acid composition of sperm membrane and lay a foundation for the manipulation of membrane integrity, fluidity, and stability to advance the assisted reproductive technologies.