DNA damage and chromosomal aberrations in various types of male factor infertility

Micronucleus counts correlating with male infertility: a clinical analysis of chromosomal abnormalities and reproductive parameters

ABSTRACT

Investigating the correlation between micronucleus formation and male infertility has the potential to improve clinical diagnosis and deepen our understanding of pathological progression. Our study enrolled 2252 male patients whose semen was analyzed from March 2023 to July 2023. Their clinical data, including semen parameters and age, were also collected. Genetic analysis was used to determine whether the sex chromosome involved in male infertility was abnormal (including the increase, deletion, and translocation of the X and Y chromosomes), and subsequent semen analysis was conducted for clinical grouping purposes. The participants were categorized into five groups: normozoospermia, asthenozoospermia, oligozoospermia, oligoasthenozoospermia, and azoospermia. Patients were randomly selected for further study; 41 patients with normozoospermia were included in the control group and 117 patients with non-normozoospermia were included in the study group according to the proportions of all enrolled patients. Cytokinesis-block micronucleus (CBMN) screening was conducted through peripheral blood. Statistical analysis was used to determine the differences in micronuclei (MNi) among the groups and the relationships between MNi and clinical data. There was a significant increase in MNi in infertile men, including those with azoospermia, compared with normozoospermic patients, but there was no significant difference between the genetic and nongenetic groups in azoospermic men. The presence of MNi was associated with sperm concentration, progressive sperm motility, immotile spermatozoa, malformed spermatozoa, total sperm count, and total sperm motility. This study underscores the potential utility of MNi as a diagnostic tool and highlights the need for further research to elucidate the underlying mechanisms of male infertility.

Biological (microfloral) factors of influence on cytogenetic stability during chemical mutagenesis

The article presents the results of a study of chromosomal mutations in residents living in the Aral Sea disaster zone. The present study was designed to evaluate the impact of the combined effect of a chemical mutagen (nickel) and bacterial microflora on the level of chromosomal aberrations (CA) in peripheral blood lymphocytes. This study used classical methods of cell cultivation, methods for determining chromosomal aberrations, a cytomorphological method for assessing epithelial cells, and an atomic absorption method for determining trace elements in the blood. The article shows that with an increase of chemical agent in the blood, the number of cells with features of damage and cells with contamination by microflora increases. Both of these factors cause an increase in the frequency of chromosomal aberrations. The article demonstrates how being exposed to a chemical factor increases chromosomal mutations, and also damages membrane components, which leads to a decrease in the barrier and protective function of the cell, and as a result also affects the level of chromosomal aberrations.

Tools used to assay genomic instability in cancers and cancer meiomitosis

Genomic instability is a defining characteristic of cancer and the analysis of DNA damage at the chromosome level is a crucial part of the study of carcinogenesis and genotoxicity. Chromosomal instability (CIN), the most common level of genomic instability in cancers, is defined as the rate of loss or gain of chromosomes through successive divisions. As such, DNA in cancer cells is highly unstable. However, the underlying mechanisms remain elusive. There is a debate as to whether instability succeeds transformation, or if it is a by-product of cancer, and therefore, studying potential molecular and cellular contributors of genomic instability is of high importance. Recent work has suggested an important role for ectopic expression of meiosis genes in driving genomic instability via a process called meiomitosis. Improving understanding of these mechanisms can contribute to the development of targeted therapies that exploit DNA damage and repair mechanisms. Here, we discuss a workflow of novel and established techniques used to assess chromosomal instability as well as the nature of genomic instability such as double strand breaks, micronuclei, and chromatin bridges. For each technique, we discuss their advantages and limitations in a lab setting. Lastly, we provide detailed protocols for the discussed techniques.

Cell-free DNA discoveries in human reproductive medicine: providing a new tool for biomarker and genetic assays in ART

Cell-free DNAs (cfDNAs) are fragmented forms of DNA that are released into extracellular environments. Analyzing them, regarding either concentration or genetic/epigenetic status can provide helpful information about disorders, response to treatments, estimation of success rates, etc. Moreover, since they are presented in body fluids, evaluation of the aforementioned items would be achieved by less/non-invasive methods. In human reproduction field, it is required to have biomarkers for prediction of assisted reproduction techniques (ART) outcome, as well as some non-invasive procedures for genetic/epigenetic assessments. cfDNA is an appropriate candidate for providing the both approaches in ART. Recently, scientists attempted to investigate its application in distinct fields of reproductive medicine that resulted in discovering its applicability for biomarker and genetic/epigenetic analyses. However, due to some limitations, it has not reached to clinical administration yet. In this article, we have reviewed the current reported data with respect to advantages and limitations of cfDNA utilization in three fields of ART, reproduction of male and female, as well as in vitro developed embryos.

Met promotes the formation of double minute chromosomes induced by Sei-1 in NIH-3T3 murine fibroblasts

BACKGROUND

Sei-1 is an oncogene capable of inducing double minute chromosomes (DMs) formation. DMs are hallmarks of amplification and contribute to oncogenesis. However, the mechanism of Sei-1 inducing DMs formation remains unelucidated.

RESULTS

DMs formation significantly increased during serial passage in vivo and gradually decreased following culture in vitro. micro nuclei (MN) was found to be responsible for the reduction. Of the DMs-carrying genes, Met was found to be markedly amplified, overexpressed and highly correlated with DMs formation. Inhibition of Met signaling decreased the number of DMs and reduced the amplification of the DMs-carrying genes. We identified a 3.57Mb DMs representing the majority population, which consists of the 1.21 Mb AMP1 from locus 6qA2 and the 2.36 Mb AMP2 from locus 6qA2-3.

MATERIALS AND METHODS

We employed NIH-3T3 cell line with Sei-1 overexpression to monitor and characterize DMs in vivo and in vitro. Array comparative genome hybridization (aCGH) and fluorescence in situ hybridization (FISH) were performed to reveal amplification regions and DMs-carrying genes. Metaphase spread was prepared to count the DMs. Western blot and Met inhibition rescue experiments were performed to examine for involvement of altered Met signaling in Sei-1 induced DMs. Genomic walking and PCR were adopted to reveal DMs structure.

CONCLUSIONS

Met is an important promotor of DMs formation.

Smoking and Male Infertility: An Evidence-Based Review

Many studies have reported that the contents of cigarette smoke negatively affect sperm parameters, seminal plasma, and various other fertility factors. Nevertheless, the actual effect of smoking on male fertility is not clear. The effect of smoking on semen parameters is based on the well-established biological finding that smoking increases the presence of reactive oxygen species, thereby resulting in oxidative stress (OS). OS has devastating effects on sperm parameters, such as viability and morphology, and impairs sperm function, hence reducing male fertility. However, not all studies have come to the same conclusions. This review sheds light upon the arguable association between smoking and male fertility and also assesses the impact of non-smoking routes of tobacco consumption on male infertility. It also highlights the evidence that links smoking with male infertility, including newly emerging genetic and epigenetic data, and discusses the clinical implications thereof.

Association between sister chromatid exchange and double minute chromosomes in human tumor cells

Background

Double minute chromosomes (DMs) are the cytogenetic hallmark of extra-chromosomal genomic amplification. They can well represent the advanced stage of malignancy. However, the mechanisms of DM generation are still not fully understood. Here, the sister chromatid exchange (SCE) was used to determine whether the occurrence of DMs was related to the high genomic instability in human carcinoma cells. We analyzed SCE frequencies in two groups of cell lines: the first group contained DM-positive cell lines such as UACC-1598, SK-PN-DW, and NCI-N87 carcinomas, while the second group comprised DM-negative cell lines including HO-8910, U251, and MGC-803.

Results

The data showed that SCE was significantly increased in the DM-positive cells as compared to the DM-negative cells. In addition, there was a positive correlation between the incidence of DMs and the SCE frequency in the UACC-1598, SK-PN-DW, and NCI-N87 carcinoma cells.

Conclusions

Because SCE can reflect general genome instability, it is suggested that the DMs are likely to be closely associated with genomic instability in carcinoma cells. Meanwhile, SCE may be involved in the malignant progression of DM-positive cancers.

Sperm nuclear vacuoles in relation to acrosome reactions and sperm motility

We investigated sperm nuclear vacuolation in relation to acrosome reactions and the maintenance of sperm motility. Thirty male patients who visited our Male Infertility Clinic were enrolled. These patients underwent conventional semen analyses, Acrobeads tests, and high-magnification observation of the sperm head to evaluate the degree of nuclear vacuolation on the Acrobeads test scoring after 24 hours of incubation. The presence of acrosome reactions was evaluated using the Acrobeads test. The spermatozoa were classified into three groups: (I) those bound to MH61-beads, (II) motile spermatozoa that did not bind to MH61-beads, and (III) immotile spermatozoa that did not bind to MH61-beads. The percentage of spermatozoa with large nuclear vacuoles (%LNV) was compared between the three groups. The degree of sperm nuclear vacuolation was evaluated in 17,992 ejaculated spermatozoa. The mean %LNVs were 2.4% in group I, 5.8% in group II, and 9.8% in group III. These values were significantly different from each other (P < 0.001, paired t-test). There were no correlations between the %LNV values and the Acrobeads scores. In conclusion, the degree of sperm nuclear vacuolation was significantly lower in the acrosome-reacted spermatozoa and spermatozoa with maintained motility, and higher in the immotile spermatozoa that did not bind to MH61-beads.

Observation of spermatozoa by a high-magnification microscope

Semen analyses are the primary tool for evaluating male infertility, as semen parameters are useful for predicting potential fertility. In the field of assisted reproductive technology (ART), the single best motile spermatozoon should be selected, especially when performing intracytoplasmic sperm injection (ICSI). In this context, the motile sperm organelle morphology examination (MSOME) was developed as a method of assessing the detailed morphology of motile spermatozoa in real time at a magnification of up to 6,300× on a video system. The use of ICSI with MSOME-selected sperm is called intracytoplasmic morphologically selected sperm injection (IMSI). IMSI improves the outcomes of ICSI. MSOME can be also applied to evaluate male infertility. Among MSOME parameters, the presence of sperm nuclear vacuoles is the most important finding. Large sperm nuclear vacuoles (LNV) are related not only to poor ART outcomes, but also to poor semen quality and sperm DNA damage, such as DNA fragmentation and chromatin condensation failure. It has been suggested that sperm head vacuoles are produced at earlier stages of sperm maturation. It is possible that the number of LNV can be decreased by surgical or medical treatment for male infertility. Therefore, the level of LNV has the potential to be used as an alternative parameter of semen quality and a new tool for evaluating the therapeutic effects of treatment in male patients with infertility.

Genome instability in AZFc region on Y chromosome in leukocytes of fertile and infertile individuals following exposure to gamma radiation

PURPOSE

Men are exposed to various doses of ionizing radiation due to living in regions with high natural background radiation, accidentally, occupationally or for cancer treatment. To study genomic instability of AZFc region to gamma radiation, blood samples from normal, oligozoospermia, and azoospermia individuals were irradiated by a Co-60 source.

METHODS

Irradiated cells were kept for 48 h in order to repair initial DNA damages. Real time PCR was performed for three markers (SY 1206, SY 1197, SY 579) for testing copy number variation before and after irradiation. Copy number variations were compared by calculation of cycle threshold comparative method.

RESULTS

Copy number variations of studied markers in AZFc region (microdeletion and duplication) in all samples after exposure to radiation increased with a dose dependent fashion. The frequency of instability was significantly higher in samples from infertile men in comparison with fertile ones (p < 0.001).

CONCLUSION

No significant difference was seen between the two infertile groups (p > 0.05). This observation might be a possible explanation for induction of azoospermia and oligozoospermia after radiotherapy. Increased frequency of induced microdeletion and duplication in infertile men compared with normal might be attributed to the deficiency in repair systems and the genetic factors involved in incomplete spermatogenesis of infertile men.

Increased frequency of micronuclei in lymphocytes of infertile males after exposure to gamma irradiation: a possible sign of genomic instability

PURPOSE

Induced chromosomal instability and micronucleus (MN) formation in blood lymphocytes of infertile men in comparison with fertile men exposed to gamma radiation was investigated.

METHODS

Blood samples of healthy and infertile donors were irradiated by 2 and 4 Gy Co-60 gamma-rays, then cultured in RPMI-1640 complete medium containing 1% phytoheamaglutinin (PHA) and incubated in a CO(2) incubator. Cytochalasin-B was added to the cultures at a final concentration of 4 μg/ml. Finally, harvesting, slide making, and analysis were performed according to standard procedures.

RESULTS

We observed a statistically significant difference between the frequencies of micronuclei in lymphocytes of infertile individuals, compared to healthy donors, before and after exposure to gamma rays. Although higher in azoospermia patients, the frequency of MN was not statistically different between infertile groups.

CONCLUSIONS

This study indicates that genomic instability in infertile men could probably contribute to the development of an impaired reproductive capacity.

Cytogenetic evaluation and DNA interaction studies of the food colorants amaranth, erythrosine and tartrazine

Food coloring agents, amaranth, erythrosine and tartrazine have been tested at 0.02-8mM in human peripheral blood cells in vitro, in order to investigate their genotoxic, cytotoxic and cytostatic potential. Amaranth at the highest concentration (8mM) demonstrates high genotoxicity, cytostaticity and cytotoxicity. The frequency of SCEs/cell was increased 1.7 times over the control level. Additionally, erythrosine at 8, 4 and 2mM shows a high cytotoxicity and cytostaticity. Finally, tartrazine seems to be toxic at 8 and 4mM. No signs of genotoxicity were observed. Reversely, tartrazine showed cytotoxicity at 1 and 2mM. Furthermore, spectroscopic titration studies for the interaction of these food additives with DNA showed that these dyes bind to calf thymus DNA and distinct isosbestic points are observed clearly suggesting binding of the dyes to DNA. Additionally DNA electrophoretic mobility experiments showed that these colorants are obviously capable for strong binding to linear dsDNA causing its degradation. PCR amplification of all DNA fragments (which previously were pre-treated with three different concentrations of the colorants, extracted from agarose gel after separation and then purified), seems to be attenuated with a manner dye concentration-dependent reflecting in a delayed electrophoretic mobility due to the possible binding of some molecules of the dyes. Evaluation of the data and curves were obtained after quantitative and qualitative analysis of the lanes of the gel by an analyzer computer program. Our results indicate that these food colorants had a toxic potential to human lymphocytes in vitro and it seems that they bind directly to DNA.

Chromosome instability in patients with chronic renal failure

OBJECTIVE

The aim of this study was to investigate the frequency of sister chromatid exchanges (SCEs), the presence of cytostaticity, cytotoxicity, and therefore, the possible genetic instability in patients with chronic renal failure (CRF) in human cultured peripheral blood lymphocytes.

METHODS

Peripheral blood lymphocytes were cultured from 32 patients with CRF (average 55.2 years) and 18 healthy blood donors (average 44.6 years), and the SCE method was applied afterward. The increase in SCE frequency was evaluated as an immediate DNA damage index, while the reduction in the values of the proliferating rate indices was evaluated as a cytostatic index and the mitotic indices as a cytotoxic index was also measured.

RESULTS

A significant increase in the SCE frequencies along with a significant reduction in mitotic indices was observed in patients with CRF compared with the controls. It is notable that there was no significant difference in SCE levels among patients with CRF and cancer, and patients with CRF alone.

CONCLUSIONS

This study illustrates increased genetic instability in patients with CRF. These results could also be of a great importance in early diagnosis to prognosticate a possible generation of neoplasm in the future.