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    Amino Acids of Seminal Plasma Associated With Freezability of Bull Sperm
    (Frontiers Media S.A., 2020) Ugur M.R.; 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. © Copyright © 2020 Ugur, Dinh, Hitit, Kaya, Topper, Didion and Memili.
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    Applications of Metabolomics in Reproductive Biology
    (wiley, 2017) Cazaux Velho A.L.; Oliveira R.; Dinh T.; Moura A.; Kaya A.; Memili E.
    Metabolomics can be performed associated with other omics approaches such as genomics, transcriptomics, and proteomics. For example, a recent study showed interesting results using an Integrative Personal Omics Profile (iPOP) to identify markers for possible diseases affecting an individual. This chapter suggests that such a method leads to an early diagnosis and facilitates prevention of certain diseases, such as type 2 diabetes, aplastic anemia, human rhinovirus infection, and respiratory syncytial virus infection. For assisted reproductive technologies (ART), metabolomics methods have been chosen as noninvasive approaches to improve the assessment of embryo quality. Metabolic profiling analysis of follicular fluids (FF) from lactating cows and heifers by gas chromatography-mass spectrometry (GC-MS) identified the presence of greater concentrations of saturated fatty acids in follicles from cows than those from heifers. Large animals have been used as models for research of human disease and physiology due to their specific physiological characteristics, sometimes similar to the human. © 2017 by John Wiley & Sons, Inc. All rights reserved.
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    Sperm Chromatin Dynamics Associated with Male Fertility in Mammals
    (wiley, 2017) Kutchy N.A.; Dogan S.; Kaya A.; Moura A.; Memili E.
    Instead of two protamines (PRM1 and PRM2) as in human and mouse sperms, presence of only PRM1 in bull sperm raises an interesting question about the mechanism(s) regulating sperm chromatin structure. During spermatogenesis, spermatozoa that are present in syncytium share mRNA and proteins through cytoplasmic bridges and are phenotypically diploid. Chromatin remodeling occurs during spermatogenesis where linker histones are gradually replaced by testis-specific variants, followed by the replacement of histones with transition proteins and then with protamines. Increased percentage of histone retention is expected to cause infertility in males. Although protamines are involved in sperm chromatin condensation and function, there is restrictive positive selection on only a few functional sites. Improper packaging of sperm DNA caused partly by reduced protamination predisposes sperm DNA to damage, which then interferes with fertilization and early embryonic development. Abnormal chromatin condensation in sperm during spermatogenesis and abnormal chromatin decondensation during pronucleus formation (postfertilization) can result in reproductive problems. © 2017 by John Wiley & Sons, Inc. All rights reserved.