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Persulfidation contributes to a group of redox post-translational modifications (PTMs), which arise exclusively on the sulfhydryl group of cysteine as a result of hydrogen sulfide (H2S) action. Redox-active molecules, including H2S, contribute to sperm development; therefore, redox PTMs represent an extremely important signalling pathway in sperm life. In this path, persulfidation prevents protein damage caused by irreversible cysteine hyperoxidation and thus maintains this signalling pathway. In our study, we detected both H2S and its production by all H2S-releasing enzymes (cystathionine γ-lyase (CTH), cystathionine β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (MPST)) in male reproduction, including spermatozoa. We provided evidence that sperm H2S leads to persulfidation of proteins, such as glyceraldehyde-3-phosphate dehydrogenase, tubulin, and anchor protein A-kinase. Overall, this study suggests that persulfidation, as a part of the redox signalling pathway, is tightly regulated by enzymatic H2S production and is required for sperm viability.

Sperm physiology is mainly affected by the functions of testis and, during spermatogenesis, sperm are provided of proteins driving posterior motility (Björkgren & Sipilä, 2019). For example, NAD +dependent histone deacetylases (Sirtuins) need to be expressed in testes for proper sperm motility (Coussens et al., 2008). Moreover, spermatozoa are transcriptionally and translationally silent, therefore the ability to acquire fertilization competence, i.e. support capacitation and hyperactivation, depends on the proteins already synthesized during spermatogenesis. Interestingly, aging results in decreased sirtuin 1 (SIRT1) expression in testes (Grabowska et al., 2017) and defective basal sperm motility (prior to capacitation). However, whether this SIRT1 insufficiency affects posterior sperm ability to hyperactivate deserves to be studied. To test this possibility, we compared the dynamics of motility-based sperm subpopulations during capacitation and fertilization ability of Sirt1 +/− mutant males and wild-type (WT) siblings. Our study support that (I) SIRT1 contributes sperm to go through hyperactivation and (II) Sirt1 +/− mice as good model to identify molecular factors developing the age-related sub-/infertility. | ME THODS | AnimalsFourteen to 18-week-old males of germ-line Sirt1 +/− (n = 3) and their WT (Sirt1 +/+ ) siblings (n = 3) were used. Sirt1 +/− genotype is based on the excision of exons 5, 6 and 7 of Sirt1 allele. Animal procedures were done in accordance with the ActNo.246/1992 of the Animal Welfare Advisory Committee (Czech Republic).

Only a fraction of specimens under study are usually selected for quantification in histology. Multilevel sampling or tissue probes, slides and fields of view (FOVs) in the regions of interest (ROIs) are required. In general, all parts of the organs under study should be given the same probability to be taken into account; that is, the sampling should be unbiased on all levels. The objective of our study was to provide an overview of the use of virtual microscopy in the context of developing sampling strategies of FOVs for stereological quantification. We elaborated this idea on 18 examples from

Idiopathic infertility is a serious problem, which can be caused and explained by exposure to endocrine disruptors, such as bisphenols. In our study, we studied transactional exposure to bisphenol and its effects on newborn male mice throughout their reproductive life. Newborn male mice were exposed to bisphenol S and bisphenol F through maternal milk from post-natal day 0 to post-natal day 15 at concentrations of 0.1 ng.g/bw/day and 10 ng.g/bw/day, respectively. Although there were minimal differences between the control and experimental groups in testicular tissue quality and spermatozoa quality, we discovered an interesting influence on early embryonic development. Moderate doses of bisphenol negatively affected cleavage of the early embryo and subsequently, the blastocyst rate, as well as the number of blastomeres per blastocyst. In our study, we focused on correlations between particular stages from spermatogenesis to blastocyst development. We followed epigenetic changes such as dimethylation of histone H3 and phosphorylation of histone H2 from germ cells to blastocysts; we discovered the transfer of DNA double-strand breaks through the paternal pronucleus from spermatozoa to blastomeres in the blastocyst. We elucidated the impact of sperm DNA damage on early embryonic development, and our results indicate that idiopathic infertility in adulthood may have causes related to the perinatal period.

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