Mouse Germ Cells Research Articles

Detection of bitterness in vitro by a novel male mouse germ cell-based biosensor

Bitter detection has attracted extensive attention in industries and researches due to pharmacological and/or food safety issues. Common electronic tongues constructed with electrochemical, optical or mass sensors are often subjected to the drawback of low-specificity in detecting a wide range of bitter compounds with diverse chemical structures and functions. However, biological gustatory components present unique specificity to bitter compounds, which may provide a promising approach in bitter detection. The activation of G protein coupled receptors (GPCRs) by ligands will affect cell morphology in a specific manner, which can be monitored by cell-impedance sensor. Thus cells expressing bitter receptors (a subfamily of GPCRs) can be used as sensing material in specific bitter detection. In this study, we explored the feasibility of utilizing male mouse germ cells in testis and cell-based impedance sensors (CIS) to build a cell-based bitter biosensor. Male mouse germ cells express bitter receptor T2Rs, which can sensitively and specifically respond to bitter compounds. To verify bitter sensing capacity of the germ cells, calcium responses of germ cells to three bitter compounds were examined prior to cell impedance response measurement. Furthermore, a bitter receptor blocker, probenecid, was used to verify the specificity of T2R-mediated impedance responses in germ cells. Cell-impedance response profiles of germ cells to four bitter compounds were investigated by analyzing the response intensity under various concentrations. Finally, impedance responses to five basic tastes were examined to evaluate the performance of cell-based bitter biosensor in bitter detection. The results revealed that this hybrid bitter biosensor could respond to those bitter compounds in a dose-dependent manner. The detection threshold for quinine was 0.125mM, lower than our previous cell-based bitter biosensor. The calcium imaging tests and use of probenecid confirmed that T2R activation contributed to the cell impedance responses of this cell-based biosensor. Moreover, this germ cell-based cell could specifically detect bitter compounds among five taste stimuli, which may provide a promising and valuable approach for detection of various bitter compounds.

Profiling of gender-specific gene expression in female and male primordial germ cells in mice

After complete migration of primordial germ cells (PGCs) into the genital ridges by E13.5 in mice, they undergo a gender-specific fate: Male and female PGCs undergo mitotic arrest and meiosis, respectively. However, differentiation of PGCs on a gender-specific basis remained poorly understood. The aim of this study was to gain further insight into the gender-specific features of PGCs in mice.

Expression of steroidogenesis-related genes in murine male germ cells

For decades, only few tissues and cell types were defined as steroidogenic, capable of de novo steroid synthesis from cholesterol. However, with the refinement of detection methods, several tissues have now been added to the list of steroidogenic tissues. Besides their critical role as long-range acting hormones, steroids are also playing more discreet roles as local mediators and signaling molecules within the tissues they are produced. In testis, steroidogenesis is carried out by the Leydig cells through a broad network of proteins, mediating cholesterol delivery to CYP11A1, the first cytochrome of the steroidogenic cascade, and the sequential action of enzymes insuring the production of active steroids, the main one being testosterone. The knowledge that male germ cells can be directly regulated by steroids and that they express several steroidogenesis-related proteins led us to hypothesize that germ cells could produce steroids, acting as autocrine, intracrine and juxtacrine modulators, as a way to insure synchronized progression within spermatogenic cycles, and preventing inappropriate cell behaviors between neighboring cells. Gene expression and protein analyses of mouse and rat germ cells from neonatal gonocytes to spermatozoa showed that most steroidogenesis-associated genes are expressed in germ cells, showing cell type-, spermatogenic cycle-, and age-specific expression profiles. Highly expressed genes included genes involved in steroidogenesis and other cell functions, such as Acbd1 and 3, Tspo and Vdac1-3, and genes involved in fatty acids metabolism or synthesis, including Hsb17b4 10 and 12, implying broader roles than steroid synthesis in germ cells. These results support the possibility of an additional level of regulation of spermatogenesis exerted between adjacent germ cells.

DNA methylation and gene expression dynamics during spermatogonial stem cell differentiation in the early postnatal mouse testis.

BackgroundIn the male germline, neonatal prospermatogonia give rise to spermatogonia, which include stem cell population (undifferentiated spermatogonia) that supports continuous spermatogenesis in adults. Although the levels of DNA methyltransferases change dynamically in the neonatal and early postnatal male germ cells, detailed genome-wide DNA methylation profiles of these cells during the stem cell formation and differentiation have not been reported.ResultsTo understand the regulation of spermatogonial stem cell formation and differentiation, we examined the DNA methylation and gene expression dynamics of male mouse germ cells at the critical stages: neonatal prospermatogonia, and early postntal (day 7) undifferentiated and differentiating spermatogonia. We found large partially methylated domains similar to those found in cancer cells and placenta in all these germ cells, and high levels of non-CG methylation and 5-hydroxymethylcytosines in neonatal prospermatogonia. Although the global CG methylation levels were stable in early postnatal male germ cells, and despite the reported scarcity of differential methylation in the adult spermatogonial stem cells, we identified many regions showing stage-specific differential methylation in and around genes important for stem cell function and spermatogenesis. These regions contained binding sites for specific transcription factors including the SOX family members.ConclusionsOur findings show a distinctive and dynamic regulation of DNA methylation during spermatogonial stem cell formation and differentiation in the neonatal and early postnatal testes. Furthermore, we revealed a unique accumulation and distribution of non-CG methylation and 5hmC marks in neonatal prospermatogonia. These findings contrast with the reported scarcity of differential methylation in adult spermatogonial stem cell differentiation and represent a unique phase of male germ cell development.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1833-5) contains supplementary material, which is available to authorized users.

Endonuclease G is Upregulated and Required in Testicular Germ Cell Apoptosis after Exposure to 60 Hz at 200 μT

Several reports supported that continuous exposure to 60 Hz magnetic field (MF) induces testicular germ cell apoptosis in vivo. We recently evaluated duration- and dose-dependent effects of continuous exposure to a 60 Hz MF on the testes in mice. BALB/c male mice were exposed to a 60 Hz MF at <TEX>$100{\mu}T$</TEX> for 24 hours a day for 2, 4, 6, or 8 weeks, and at 2, 20 or <TEX>$200{\mu}T$</TEX> for 24 hours a day for 8 weeks. To induce the apoptosis of testicular germ cell in mice, the minimum dose is <TEX>$20{\mu}T$</TEX> at continuous exposure to a 60 Hz MF for 8 weeks, and the minimum duration is 6 weeks at continuous exposure of <TEX>$100{\mu}T$</TEX>. Continuous exposure to a 60 Hz MF might affect duration- and dose-dependent biological processes including apoptotic cell death and spermatogenesis in the male reproductive system of mice. The safety guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) indicates that the permissible maximum magnetic flux density for general public exposure is <TEX>$200{\mu}T$</TEX> at 60 Hz EMF (ICNIRP Guidelines, 2010). In the present study, we aimed to examine the expression of pro- and anti-apoptotic genes regulated by the continuous exposure to 60 Hz at <TEX>$200{\mu}T$</TEX> in Sprague-Dawley rats for 20 weeks. The continuous exposure to 60 Hz at <TEX>$200{\mu}T$</TEX> does not affect the body and testicular weight in rats. However, exposure to 60 Hz MF significantly affects testicular germ cell apoptosis and sperm count. Further, the apoptosis-related gene was scrutinized after exposure to 60 Hz at <TEX>$200{\mu}T$</TEX> for 20 weeks. We found that the message level of endonuclease G (EndoG) was greatly increased following the exposure to 60 Hz at <TEX>$200{\mu}T$</TEX> compared with sham control. These data suggested that 60 Hz magnetic field induced testicular germ cell apoptosis through mitochondrial protein Endo G.

Dominant lethal mutation test in male mice exposed to 900 MHz radiofrequency fields

Adult male ICR mice were exposed to continuous wave 900MHz radiofrequency fields (RF) at 1.6mW/cm2 power intensity (whole body average specific absorption rate of 0.731W/kg) for 4 hour/day for 15 days. At the end of exposure, each mouse was caged with 3 mature virgin female mice for mating. After 7 days, each male mouse was transferred to a fresh cage and mated with a second batch of 3 females. This process was repeated for a total of 4 consecutive weeks. Sham exposed male mice and those subjected to an acute 2Gy γ-irradiation (GR) were handled similarly and used as un-exposed and positive controls, respectively. All females were sacrificed on the 18th day of gestation and presumptive mating and, the contents in their uteri were examined. The overall observations during the 4 weeks of mating indicated that the un-exposed female mice mated to RF-exposed male mice showed no significant differences in the percentage of pregnancies, total implants, live implants and dead implants when compared with those mated with sham-exposed mice. In contrast, female mice mated with GR-exposed males showed a consistent pattern of significant differences in the above indices in each and all 4 weeks of mating. Thus, the data indicated an absence of mutagenic potential of RF exposure in the germ cells of male mice.

Novel characterization of the HSPA2-stabilizing protein BAG6 in human spermatozoa.

While a large cohort of sperm surface receptors underpin sperm-oocyte adhesion processes, our recent work has revealed that the molecular chaperone Heat Shock Protein A2 (HSPA2) is a key regulator of zona pellucida-receptor complex assembly in our own species. Indeed, in the infertile population, spermatozoa that fail to interact with the zona pellucida of the oocyte consistently lack HSPA2 protein expression. While the mechanisms behind this protein deficiency are under consideration, BCL2-associated athanogene 6 (BAG6) has been identified as a key regulator of HSPA2 stability in mouse germ cells. However, in the human, the presence of BAG family proteins remains completely uncharacterized. Consequently, this study aimed to determine the presence of BAG6 in human sperm cells and to characterize its putative interaction with HSPA2 throughout sperm cell development. BAG6 was shown to co-localize with HSPA2 in human testicular germ cells and epididymal spermatozoa. Similarly, BAG6 was identified in the equatorial region of non-capacitated spermatozoa but underwent a marked relocation to the anterior region of the head upon the induction of capacitation in these cells. Protein-protein interaction assays revealed the stable interaction of BAG6 and HSPA2 proteins in mature spermatozoa. Furthermore, examination of the spermatozoa of infertile men with zona pellucida binding defects, related to a lack of HSPA2, revealed a concomitant deficiency in BAG6 protein expression. In view of the findings described in this study, we propose that BAG6 is likely a key regulator of HSPA2 stability/function in human germ cells. Moreover, its under-representation in spermatozoa with zona pellucida binding deficiency suggests that BAG6 may be an important candidate to study for a further understanding of male idiopathic infertility.

Identification and Characterization of Xlr5c as a Novel Nuclear Localization Protein in Mouse Germ Cells.

BackgroundSpermatogenesis is the complex process by which diploid stem cells generate haploid germ cells in gamete production. Members of the Xlr (X-chromosome linked, lymphocyte regulated) superfamily play essential roles in spermatogenesis. The expression, localization and role in spermatogenesis of one such member, Xlr5c, has not been reported previously.Methodology/Principal FindingsXlr5c mRNA and protein levels in murine testes and other tissues were investigated using RT-PCR and Western blotting. Xlr5c was abundantly transcribed in mouse testes, particularly during the early stages of spermatogenesis and throughout prophase I in the nuclei of spermatocytes. Xlr5c was specifically localized at synaptonemal complexes(SCs) region in preleptotene and pachytene spermatocytes, as was the homologous Xlr protein Sycp3.Conclusions/SignificanceThese results suggest that Xlr5c was abundantly transcribed in germ cells, localized at SCs region, where it may play a potential role during the early stages of spermatogenesis. Identification and characterization of this novel testis protein may offer a new perspective for understanding of the molecular mechanisms involved in germ cell differentiation.

Meikin Is a Conserved Regulator of Meiosis I–Specific Kinetochore Function

The kinetochore is a multiprotein complex that connects centromeres to microtubules in meiosis and mitosis. It plays an essential role in chromosome segregation. During meiosis I, unlike in mitosis, sister kinetochores are captured by microtubules from the same spindle pole (mono-orientation) and protect centromeric cohesion mediated by cohesin protein at the onset of anaphase. These 2 kinetochore functions, mono-orientation and centromeric cohesion protection, are widely conserved among eukaryotic organisms. The mechanism for conservation is unknown. A meiotic factor has been identified in budding and fission yeasts that regulates kinetochore function during segregation. It has been postulated that a similar factor exists in eukaryotes, but this factor—which could be the master regulator of meiotic chromosome segregation—has not been identified. The investigators identified a meiosis-specific kinetochore factor in mouse germ cells that functions in meiosis I but not in meiosis II or mitosis. They named this factor MEIKIN (meiosis-specific kinetochore protein). MEIKIN is expressed and localized to kinetochores. Mono-orientation and cohesion protection are defective in knockout mice unable to express the MEIKIN gene. Both male and female Meikin knockout mice are infertile. MEIKIN plays an essential role in both mono-orientation and centromeric cohesion protection, partly by stabilizing the localization of shugoshin, a protein that protects centromeric cohesin in mouse meiosis1. In mice as well as yeast, MEIKEN also regulates the activity of Polo-like kinase PLK1, which appears to be required for both kinetochore mono-orientation and centromeric cohesion protection. MEIKIN enriches PLK1 to kinetochores during segregation. These data show that MEIKEN, a meiosis-specific kinetochore protein identified in mice, has striking biochemical and functional similarities to a regulatory factor in fission yeast. It appears to be the long-awaited master regulator of meiotic chromosome segregation conserved in living organisms from yeasts to humans. It is possible that MEIKIN dysfunction could be associated with age-associated chromosome segregation errors, a major cause of birth defects in humans.

Disperse Red 1 (textile dye) induces cytotoxic and genotoxic effects in mouse germ cells.

Disperse Red 1 (DR1), which is widely used in the textile industry, is an azo dye that contributes to the toxicity and pollution of wastewater. To assess the toxic effects of DR1 on reproduction, sexually mature male mice (Mus musculus, strain CF-1) were orally (gavage) treated with single doses of the compound at 20, 100 and 500 mg/kg body weight. Testicular features and sperm parameters were evaluated 8.3, 16.6 and 24.9 days after treatments. In addition to testicular toxicity caused by the dye, the data clearly showed an increased frequency of sperm with abnormal morphology and decreased fertility. An increased amount of DNA damage was also detected in testis cells 16.6 and 24.9 days after treatments with 100 and 500 mg/kg. This study demonstrated the toxic and genotoxic effects of DR1, indicating the harmful activity of this dye on reproductive health.

Single-molecule PCR analysis of an unstable microsatellite for detecting mutations in sperm of mice exposed to chemical mutagens

Single-molecule PCR (SM-PCR) analysis of long and repetitive DNA sequences, known as expanded simple tandem repeats (ESTRs), has been the most efficient method for studying germline mutation induction in endogenous sequences to date. However, the long length of these sequences makes mutation detection imprecise and laborious, and they have been characterized only in mice. Here, we explore the use of unstable microsatellite sequences that can be typed with high precision by capillary electrophoresis as alternative loci for detecting germline mutations. We screened 24 microsatellite loci across inbred mouse strains and identified Mm2.2.1 as the most polymorphic microsatellite locus. We then optimized SM-PCR of Mm2.2.1 to detect mutations in sperm. SM-PCR analysis of sperm from untreated B6C3F1 and Muta™Mouse samples revealed mutation frequencies that are consistent with rates derived from family pedigree analysis (∼5×10−3). To determine whether this locus can be used to detect chemically induced germline mutations, Muta™Mouse males were exposed by oral gavage to a single dose of 100mg/kg of N-ethyl-N-nitrosourea (ENU) or to 100mg/kg of benzo(a)pyrene (BaP) for 28 days alongside vehicle treated controls. Sperm were collected 10 weeks post-ENU exposure to sample sperm exposed as spermatogonial stem cells and 6 weeks post-BaP exposure to sample sperm that were dividing spermatogonia when the exposure was terminated. Both treatments resulted in a significant (approximately 2-fold) increase in mutation frequency in sperm compared to the control animals. The work establishes the utility of this microsatellite for studying mutation induction in the germ cells of mice. Because microsatellites are found in virtually every species, this approach holds promise for other organisms, including humans.

Induction of DNA Damage and G2 Cell Cycle Arrest by Diepoxybutane through the Activation of the Chk1-Dependent Pathway in Mouse Germ Cells

1,2:3,4-Diepoxybutane (DEB) is a major carcinogenic metabolite of 1,3-butadiene (BD), which has been shown to cause DNA strand breaks in cells through its potential genotoxicity. The adverse effect of DEB on male reproductive cells in response to DNA damage has not been thoroughly studied, and the related mechanism is yet to be elucidated. Using mouse spermatocyte-derived GC-2 cells, we demonstrated in the present study that DEB caused the proliferation inhibition and marked cell cycle arrest at the G2 phase but not apoptosis. DEB also induced DNA damage as evidenced by γ-H2AX expression, the comet assay, and the cytokinesis-block micronucleus assay. Meanwhile, DEB triggered the Chk1/Cdc25c/Cdc2 signal pathway, which could be abated in the presence of UCN-01 or Chk1 siRNA. GC-2 cells exposed to DEB experienced ROS generation and pretreatment of N-acetyl-l-cysteine, partly attenuated DEB-induced DNA damage, and G2 arrest. Furthermore, measurement of testicular cells showed an increased proportion of tetraploid cells in mice administrated with DEB, alongside the enhanced expression of p-Chk1. Also, the defective reproductive phenotypes, including reduced sperm motility, increased sperm malformation, and histological abnormality of testes, were observed. In conclusion, these results suggest DEB induces DNA damage and G2 cell cycle arrest by activating the Chk1-dependent pathway, while oxidative stress may be associated with eliciting toxicity in male reproductive cells.

Adenine Nucleotide Translocase 4 Is Expressed Within Embryonic Ovaries and Dispensable During Oogenesis

Adenine nucleotide translocase (Ant) facilitates the exchange of adenosine triphosphate across the mitochondrial inner membrane and plays a critical role for bioenergetics in eukaryotes. Mice have 3 Ant paralogs, Ant1 (Slc25a4), Ant2 (Slc25a5), and Ant4 (Slc25a31), which are expressed in a tissue-dependent manner. We previously identified that Ant4 was expressed exclusively in testicular germ cells in adult mice and essential for spermatogenesis and subsequently male fertility. Further investigation into the process of spermatogenesis revealed that Ant4 was particularly highly expressed during meiotic prophase I and indispensable for normal progression of leptotene spermatocytes to the stages thereafter. In contrast, the expression and roles of Ant4 in female germ cells have not previously been elucidated. Here, we demonstrate that the Ant4 gene is expressed during embryonic ovarian development during which meiotic prophase I occurs. We confirmed embryonic ovary-specific Ant4 expression using a bacterial artificial chromosome transgene. In contrast to male, however, Ant4 null female mice were fertile although the litter size was slightly decreased. They showed apparently normal ovarian development which was morphologically indistinguishable from the control animals. These data indicate that Ant4 is a meiosis-specific gene expressed during both male and female gametogenesis however indispensable only during spermatogenesis and not oogenesis. The differential effects of Ant4 depletion within the processes of male and female gametogenesis may be explained by meiosis-specific inactivation of the X-linked Ant2 gene in male, a somatic paralog of the Ant4 gene.

HnRNP K coordinates transcriptional silencing by SETDB1 in embryonic stem cells.

Retrotransposition of endogenous retroviruses (ERVs) poses a substantial threat to genome stability. Transcriptional silencing of a subset of these parasitic elements in early mouse embryonic and germ cell development is dependent upon the lysine methyltransferase SETDB1, which deposits H3K9 trimethylation (H3K9me3) and the co-repressor KAP1, which binds SETDB1 when SUMOylated. Here we identified the transcription co-factor hnRNP K as a novel binding partner of the SETDB1/KAP1 complex in mouse embryonic stem cells (mESCs) and show that hnRNP K is required for ERV silencing. RNAi-mediated knockdown of hnRNP K led to depletion of H3K9me3 at ERVs, concomitant with de-repression of proviral reporter constructs and specific ERV subfamilies, as well as a cohort of germline-specific genes directly targeted by SETDB1. While hnRNP K recruitment to ERVs is dependent upon KAP1, SETDB1 binding at these elements requires hnRNP K. Furthermore, an intact SUMO conjugation pathway is necessary for SETDB1 recruitment to proviral chromatin and depletion of hnRNP K resulted in reduced SUMOylation at ERVs. Taken together, these findings reveal a novel regulatory hierarchy governing SETDB1 recruitment and in turn, transcriptional silencing in mESCs.

Dominant lethal effects of nocodazole in germ cells of male mice

The ability of the anticancer drug, nocodazole, to induce dominant lethal mutations in male germ cells was investigated by the in vivo dominant lethal test. Mice were treated with single doses of 15, 30 and 60 mg/kg nocodazole. These males were mated at weekly intervals to virgin females for 6 weeks. Nocodazole clearly induced dominant lethal mutations in the early spermatid stage with the highest tested dose. Mice treated with 60 mg/kg nocodazole showed an additional peak of dominant lethal induction in mature spermatozoa during the first week matings after treatment. The percentage sperm count and sperm motility were significantly decreased after treatment of males with 30 and 60 mg/kg nocodazole. Moreover, the middle and highest doses of nocodazole significantly increased the percentage of abnormal sperm. Our study provides evidence that nocodazole is a germ cell mutagen. Marked alteration in the spermiogram analysis after nocodazole treatment possibly confirms that nocodazole has a significant effect on sperm maturation and development during storage and transit. The demonstrated mutagenicity profile of nocodazole may support further development of effective chemotherapy with less mutagenicity. Moreover, the cancer patients and medical personnel exposed to this drug chemotherapy may stand a higher risk for abnormal reproductive outcomes.

Effects of benzo[a]pyrene on mouse germ cells: heritable DNA mutation, testicular cell hypomethylation and their interaction with nucleotide excision repair

Benzo[a]pyrene induces heritable mutations in male germ cells.

An interview with Norio Nakatsuji.

An interview with Norio Nakatsuji.

PRMT5 enhances generation of induced pluripotent stem cells from dairy goat embryonic fibroblasts via down-regulation of p53.

Protein arginine methyltransferase 5 (PRMT5), is thought to play a role in epigenetic reprogramming of mouse germ cells. However, up to now there has been little information concerning its expression profile and effects on generation of induced pluripotent stem cells (iPSCs) from somatic cells, in livestock. Here, we have explored PRMT5 expression profiles in dairy goats and its consequences to derivation of iPSCs from dairy goat embryonic fibroblasts (GEFs). We investigated effects of PRMT5 on iPS-like cells production in vitro. alkaline phosphatase (AP) staining, QRT-PCR and western blotting analysis of expression of related markers were used to evaluate efficiency of generation of iPSCs derived from GEFs. These showed PRMT5 to be a conservative gene widely expressed in various tissues and different-aged testes. PRMT5 overexpression in combination with OCT3/4, SOX2, KLF4 and C-MYC (POSKM) significantly increased number of AP positive iPS-like colony-derived GEFs compared to OSKM alone, in our dairy goats. Moreover, our results demonstrated that PRMT5 overexpression stimulated GEF proliferation and down-regulated p53, p21 (a target gene of p53) and the apoptotic marker caspase 3, to enhance somatic cell reprogramming. This study provides an efficient model for future studies on mechanisms underlying goat somatic cell reprogramming and differentiation.

An in vivo assay of the mutagenic potential of imidacloprid using sperm head abnormality test and dominant lethal test

Objective: To assess the mutagenic effects of imidacloprid in germ cells of Swiss albino male mice by sperm head abnormality (SHA) assay and dominant lethal test (DLT). Methods: Swiss albino mice were exposed to imidacloprid (22, 11 and 5.5 mg/kg/day) along with 3% gum acacia as vehicle control through oral route for 7, 14 and 28 days for SHA assay and for 28 days for DLT. The epididymal sperm smear in 1% eosin stain was analyzed for SHAs. In DLT, male mice were allowed to mate with females after 1, 3 and 6 weeks of end of pesticide treatment. The uterine contents of the sacrificed females were observed for live and dead implants. The analysis of test and control groups data was done by one way ANOVA at p < 0.05. Results: Exposure of all dose levels of imidacloprid (22, 11 and 5.5 mg/kg/day) for seven days did not induce significant SHAs while they induced significant SHAs compared with the control group following exposure for 14 and 28 days. The analysis of uterine content revealed a significant increase in the number of dead implants/female compared with the vehicle control in only those females which were mated with male mice after six weeks of treatment of highest dose level of imidacloprid. The dominant lethal mutations were observed only at spermatogonial stage. Conclusions: Long-term exposure of pesticide generated SHAs even at lowest dose level (5.5 mg/kg/day for 14 days) and mutagenic effects at spermatogonial stage at highest dose level (22 mg/kg/day for 28 days).

Protective effect of beta-carotene against titanium dioxide nanoparticles induced apoptosis in mouse testicular tissue.

In this study, the effects of beta-carotene (BC) on testicular germ cell apoptosis arising from titanium dioxide nanoparticles (NTiO2 ) have been evaluated. In NTiO2 -treated mice, expression of apoptotic related genes including Bid, FasL, caspase-3 and p38MAPK was significantly increased. Measurement apoptosis using TUNEL method showed significant increase in apoptotic index of germ cells in NTiO2 -treated mice (P < 0.05). TUNEL assessments showed that the increase of apoptotic index of testicular germ cells in NTiO2 -treated mice was reversed by BC. Beta-carotene pre-treatment could also effectively attenuate the expression of apoptotic related genes. The application of BC may serve as a beneficial medication to protect germ cells against apoptosis induced by nanoparticles and be helpful for male fertility.