Cytochemical tests to investigate sperm DNA damage: Assessment and review

Sperm Chromatin Status and DNA Fragmentation in Mouse Species with Divergent Mating Systems

Sperm DNA integrity and chromatin status serve as pivotal indicators of sperm quality, given their intricate link to sperm function, embryo development, and overall fertility. Defects in chromatin compaction, which are often associated with compromised protamine content, can lead to damaged DNA strands. In this study, the chromatin status and possible correlation with DNA damage was assessed in males of three mouse species: Mus musculus, M. spretus, and M. spicilegus. We employed various staining methods, including aniline blue, methylene blue (Diff-Quik), toluidine blue, and chromomycin A3, to assess chromatin compaction in cauda epididymal sperm. Samples were also analyzed by the sperm chromatin structure assay (SCSA) to estimate DNA fragmentation (%tDFI, %HDS). Analyses were carried out on freshly collected sperm and cells incubated for 3 h in a HEPES-buffered modified Tyrode's medium simulating conditions of the female reproductive tract. Notably, the analysis of chromatin status yielded minimal abnormal values across all three species employing diverse methodologies. SCSA analyses revealed distinct variations in %tDFI between species. Following sperm incubation, the percentages of sperm stained with methylene blue exhibited differences among the species and were significantly correlated to the DNA fragmentation index. HDS demonstrated correlations with the percentages of sperm stained by aniline blue, methylene blue, and chromomycin A3. Overall, chromatin compaction was high across all species, with limited differences among them. The relationship between chromatin status and DNA integrity appeared to be related to levels of sperm competition among species.

SPAG17 mediates nuclear translocation of protamines during spermiogenesis

Protamines (PRM1 and PRM2) are small, arginine-rich, nuclear proteins that replace histones in the final stages of spermiogenesis, ensuring chromatin compaction and nuclear remodeling. Defects in protamination lead to increased DNA fragmentation and reduced male fertility. Since efficient sperm production requires the translocation of protamines from the cytoplasm to the nucleus, we investigated whether SPAG17, a protein crucial for intracellular protein trafficking during spermiogenesis, participates in protamine transport. Initially, we assessed the protein-protein interaction between SPAG17 and protamines using proximity ligation assays, revealing a significant interaction originating in the cytoplasm and persisting within the nucleus. Subsequently, immunoprecipitation and mass spectrometry (IP/MS) assays validated this initial observation. Sperm and spermatids from Spag17 knockout mice exhibited abnormal protamination, as revealed by chromomycin A3 staining, suggesting defects in protamine content. However, no differences were observed in the expression of Prm1 and Prm2 mRNA or in protein levels between testes of wild-type and Spag17 knockout mice. Conversely, immunofluorescence studies conducted on isolated mouse spermatids unveiled reduced nuclear/cytoplasm ratios of protamines in Spag17 knockout spermatids compared to wild-type controls, implying transport defects of protamines into the spermatid nucleus. In alignment with these findings, in vitro experiments involving somatic cells, including mouse embryonic fibroblasts, exhibited compromised nuclear translocation of PRM1 and PRM2 in the absence of SPAG17. Collectively, our results present compelling evidence that SPAG17 facilitates the transport of protamines from the cytoplasm to the nucleus.

The Effect of Long COVID-19 Infection and Vaccination on Male Fertility; A Narrative Review

Earlier research has suggested that the male reproductive system could be particularly vulnerable to SARS-CoV-2 (COVID-19) infection, and infections involving this novel disease not only pose serious health threats but could also cause male infertility. Data from multi-organ research during the recent outbreak indicate that male infertility might not be diagnosed as a possible consequence of COVID-19 infection. Several review papers have summarized the etiology factors on male fertility, but to date no review paper has been published defining the effect of COVID-19 infection on male fertility. Therefore, the aim of this study is to review the published scientific evidence regarding male fertility potential, the risk of infertility during the COVID-19 pandemic, and the impact of COVID-19 vaccination on the male reproductive system. The effects of COVID-19 infection and the subsequent vaccination on seminal fluid, sperm count, sperm motility, sperm morphology, sperm viability, testes and sex hormones are particularly reviewed.

PRM1 Gene Expression and Its Protein Abundance in Frozen-Thawed Spermatozoa as Potential Fertility Markers in Breeding Bulls

Functional genes and proteins in sperm play an essential role in bulls’ reproductive processes. They are more accurate in determining bull fertility than conventional semen quality tests. Protamine-1 (PRM1) is a gene or protein crucial for packaging and protecting sperm DNA until fertilization affects normal sperm function. This study analyzes the genes and proteins potential from PRM1 as fertility markers for different breeds of bulls utilized in the artificial insemination programs, expected to be an accurate tool in interpreting bull fertility in Indonesia. This study used Limousin, Holstein, and Ongole Grade bulls divided into two groups based on fertility, high-fertility (HF) and low fertility (LF). The semen quality assessment included progressive motility (computer-assisted semen analysis), viability (eosin-nigrosine), and plasma membrane integrity (HOS test). Sperm DNA fragmentation (SDF) was assessed using the acridine orange staining and the Halomax test. Sperm PRM deficiency was evaluated with the chromomycin A3 method. Moreover, PRM1 gene expression was measured using qRT-PCR, and the PRM1 protein abundance was measured with the enzyme immunoassay method. Semen quality values, relative expression of PRM1 gene, and quantity of PRM1 protein were significantly higher (p < 0.05) in HF bulls than in LF bulls. The SDF and PRM deficiency values in LF bulls were significantly higher (p < 0.05) than HF bulls. Additionally, PRM1 at the gene and protein levels correlated significantly (p < 0.01) with fertility. Therefore, PRM1 is a potential candidate for fertility markers in bulls in Indonesia.

Comparison between sperm parameters and chromatin in recurrent pregnancy loss couples after antioxidant therapy

Background and Aims:

Recurrent Pregnancy loss (RPL) is a heterogeneous disease. The role of maternal factor is clear but the relationship between the paternal factors remains uncertain. It has been shown that increase the level of Reactive Oxygen Species (ROS) and decrease the antioxidant levels in men can lead to RPL. New researches show treatment with antioxidant can improved sperm parameter. The aim of the present study was to assess the effect of vitamin E plus Zinc therapy on sperm parameters and chromatin quality in couples with RPL.

Methods:

In this clinical trial study, 60 RPL patients were selected from RPL clinic. Standard sperm parameters were analyzed and then male partners were intake vitamin E and Zinc in antioxidant therapy plan for 90 days. After that, sperm parameters were analyzed again. Sperm chromatin assay was reviewed before and after vitamin E and Zinc therapy by cytochemical assay including aniline blue (AB), chromomycin A3 (CMA3), toluidine blue (TB). To assess DNA fragmentation index, TUNEL test was used. Data were analyzed and compared before and after treatment.

Results:

data analysis showed all sperm parameters significantly improved after treatment (P < 0.001). The number of AB⁺ and TB⁺ sperms were decreased significantly after vitamin E and Zinc therapy (P = 0.0001). Decrease in DNA fragmentation in post treatment group in comparison to pre-treatment was statistically significant.

Conclusion:

Supplemental of vitamin E plus Zinc may improve sperm parameters chromatin quality and decrease sperm DNA fragmentation in RPL patients.