Flow cytometric evaluation of the effect of various doses of vindesine sulphate on mouse spermatogenesis

Disruption of ubiquitin specific protease 26 gene causes male subfertility associated with spermatogenesis defects in mice†

Ubiquitin-specific protease 26 (USP26) is an X-linked gene exclusively expressed in the testis and codes for the USP26, a peptidase enzyme that belongs to the deubiquitinating enzyme family. Recent studies have indicated that mutations in USP26 affect spermatogenesis and are associated with male infertility in humans and mice. However, the exact role of USP26 in spermatogenesis and how it affects male reproduction remains unknown. In this study, we generated a conventional Usp26 knockout mouse model and found that deletion of Usp26 in male mice (Usp26-/Y) leads to significantly reduced pup numbers per litter and significantly increased intervals between two consecutive offspring. We also found that the serum follicle stimulating hormone and testosterone levels of adult Usp26-/Y mice were significantly decreased compared to those of Usp26+/Y mice. Histological examination results showed that Usp26-/Y mice had significantly increased percentage of abnormal seminiferous tubules at different ages. Flow cytometry results exhibited that Usp26-/Y mice had significantly reduced percentage of mature haploid cells in the testes compared to Usp26+/Y mice. Sperm counts in epididymis were also significantly declined in Usp26-/Y mice compared to those in Usp26+/Y mice. Immunohistochemistry and immunofluorescence staining and immunoprecipitation analysis results showed that USP26 and androgen receptor were co-localized in mouse testicular cells at different ages and they both had physiological interactions. All these results demonstrated that the loss of Usp26 affects spermatogenesis and hormone secretion and causes male subfertility. Our study also provides the evidence on the interactions between USP26 and androgen receptor in mouse testis, whereby pointing to a potential mechanism.

New insights into the potential mechanisms of spermatogenic failure in patients with idiopathic azoospermia

Idiopathic azoospermia (IA) refers to azoospermia without a clear aetiology. Due to the unclear aetiology and pathological mechanism of IA, there is no effective treatment for IA. The development of assisted reproductive and microsperm extraction technologies has brought hope to patients with IA with fertility problems. However, there are still many patients with IA whose testes lack healthy sperm, causing infertility. Therefore, it is key to identify how testicular spermatogenic failure can be reversed to promote spermatogenesis in patients with IA to resolve fertility problems; these goals are a great challenge in reproductive medicine. The underlying genetic factors seem to be important pathological factors of IA. Understanding the role of genetic factors in the pathological mechanism of spermatogenic failure in patients with IA is of great value for future studies and treatments and is also an important reference for the reproductive health of males and their offspring. A method combining sequencing technology and bioinformatics analysis is an important means to understand the genetic pathological mechanisms. We used bioinformatics analysis to study the public human IA dataset. We found that the pathogenic mechanism of IA may be related to abnormal ciliary structure and function and disrupted RNA metabolism in spermatogenic cells. Disrupted m6A regulation of spermatogenesis may be an important pathological mechanism of IA and warrants attention. Finally, we screened for key genes and potential therapeutic drugs to determine future research directions.

Determination of a new index of sexual maturity (ISM) in zebra mussel using flow cytometry: interest in ecotoxicology

The global dynamic spread of chemical contamination through the aquatic environment calls for the development of biomarkers of interest. Reproduction is a key element to be considered because it is related to the sustainability of species. Spermatogenesis is a complex process that leads to the formation of mature germ cells, whose steps and impairments need to be finely described in ecotoxicological analyses. The physiological process has been commonly described by histological analyses of gonads in different taxa. In the present paper, we describe the development of a novel technique to characterize spermatogenesis based on the analysis of the DNA content of germ cells by flow cytometry, using a DNA-intercalating agent. This new biomarker, referred to as an index of sexual maturity, proved relevant to describe the seasonal reproductive cycle of the zebra mussel, Dreissena polymorpha (Pallas, 1771), used as a sentinel species in the biomonitoring of continental waters and sensitive to highlight the reprotoxicity of carbamazepine (an anti-epileptic pharmaceutical) tested under ecosystemic conditions (mesocosms).

Flow cytometry evaluation of lead and cadmium effects on mouse spermatogenesis

Flow cytometry (FCM) is a powerful tool to evaluate cell DNA content and ploidy levels. We have assessed the accuracy of two protocols of nuclei isolation from paraffinized samples (P1 and P2) by comparing FCM results with those obtained using fresh material (F1-F3). After isolation, nuclei were stained with propidium iodide and quantitatively analysed by FCM for changes in germ cell ratios. Results obtained with Protocol P2 were similar to those obtained using the protocol that gave best results for fresh tissues (F2). Protocol P2 was then applied to paraffin embedded testicular samples from ICR-CD1 mice exposed to 1, 2 and 3 mg CdCl(2)/kg bw by single subcutaneous injection, and to 74 and 100 mg PbCl(2)/kg bw administered in four repeated doses. The highest doses of CdCl(2) decreased the number of haploid (1C) cells and increased the number of diploid (2C), S phase and tetraploid (4C) cells. Treatment with PbCl(2) did not induce significant changes in testicular cells subpopulations. These results support the usefulness of FCM in evaluating the effect of toxic substances on mouse spermatogenesis, using both fresh and paraffinized material.

Flow cytometric assessment of ethylene glycol monoethyl ether on spermatogenesis in rats

The effects of ethylene glycol monoethyl ether (EGEE) on testicular cell populations in rats were investigated by a flow cytometric method. Rats were administered by gavage with EGEE at the various doses of 0 (saline alone), 100, 200, 400, and 800 mg/kg body weight/day for 4 weeks. The treatment of EGEE caused decreases in the weight of testis and epididymis and in the number of testicular cells. Histopathologically, exfoliation of germ cells into the tubular lumen was observed at the doses of above 200 mg/kg. The treatment of EGEE at the dose of 400 mg/kg caused moderate testicular degeneration. A significant depletion of haploid cells and a disproportionate ratio of diploid and tetraploid cells were observed as determined by flow cytometric analysis. These results indicate that the toxic effect of EGEE on the male reproductive system may be strongly associated with the disproportion of testicular germ cells.

Correlation between cell survival and micronuclei formation in V79 cells treated with vindesine before exposure to different doses of gamma-radiation

Effect of 20 nM vindesine sulphate (VDS) treatment was studied on cell survival, growth kinetics and micronuclei induction in V79 cells exposed to 0-300 cGy of gamma-radiation at 16, 22 and 28 h post-irradiation. Treatment of V79 cells with VDS before exposure to different doses of gamma radiation resulted in a significant decline in cell survival and growth kinetic when compared with the concurrent PBS+irradiation group. The decline in cell survival and growth kinetics was dose related. Similarly, the cell proliferation indices also declined in a dose dependent manner in both PBS+irradiation and VDS+irradiation groups and this decline was higher in VDS+irradiation group in comparison with the PBS+irradiation group. In contrast, the frequency of micronuclei increased in a dose related manner in both PBS+irradiation and VDS+irradiation groups. However, the frequency of micronuclei was significantly greater in the VDS+irradiation group when compared to the PBS+irradiation group at all the post-irradiation time periods studied and the dose response for both groups was linear for all the scoring time periods. The biological response was determined by plotting surviving fraction and micronuclei frequencies on X- and Y-axes, respectively. The plot between surviving fraction and micronuclei induction showed a close correlation. The surviving fraction of V79 cells reduced with the increasing frequency of micronuclei in both groups and the relationship between micronuclei induction and cell survival could be fitted on a linear quadratic model.

Influence of teniposide (VM-26) on radiation-induced damage to mouse spermatogenesis: a flow cytometric evaluation

The effect of teniposide (VM-26) 0.05 mg/kg body weight treatment on spermatogenesis of mice exposed to 0, 0.5, 1, 2, and 3 Gy gamma-radiation was evaluated flow cytometrically. Whole body irradiation with 1 to 3 Gy resulted in a significant decline in testis weight from Day 14 to 35 post-irradiation depending on the exposure dose. Treatment of mice with teniposide before irradiation advanced the decline in testicular weight by several days, especially at 3 Gy, where a significant decline in testicular weight was observed at Day 7 post-irradiation when compared with the double distilled water (DDW)+irradiation group. The relative percentage of the 2C population declined significantly in the VM-26+irradiation group in comparison with the DDW+irradiation group at various post-irradiation time periods depending on the exposure dose. A significant depletion in the relative percentage of S-phase cells was observed as early as Day 1 post-irradiation in the VM-26+irradiation group when compared with the DDW+irradiation group after exposure to 1 to 3 Gy. This decline continued up to Day 21 post-irradiation after exposure to 2 Gy. The relative percentage of primary spermatocytes showed a consistent decline after exposure to various doses of gamma-radiation in the VM-26+irradiation group when compared with the DDW+irradiation group at different time periods, with a few exceptions, especially at higher doses. The pattern of decline in the relative percentage of round spermatids was similar to that of primary spermatocytes, where a significant decline was observed at various post-irradiation time periods in the VM-26+irradiation group in comparison with the DDW+irradiation group. These changes in the relative germ cell percentages are manifested as alterations in the ratios of various germ cell populations. The 4C:2C ratio declined consistently from Day 1 to Day 70 post-irradiation in the VM-26+irradiation group at all exposure doses. Similarly, the 4C:S-phase ratio in the VM-26+irradiation group also showed a significant decline at different post-irradiation time periods when compared with the DDW+irradiation group depending on the exposure dose. The reduction observed in the relative percentages of various cell populations was higher in the combination group when compared with the DDW+irradiation controls, indicating potentiation of damage to male germ cells by teniposide treatment before irradiation.