Effects of cadmium exposure during pregnancy on genome-wide DNA methylation and the CREB/CREM pathway in the testes of male offspring rats

This experimental study explored the multigenerational and transgenerational effects of cadmium (Cd) exposure during pregnancy on the testicular tissue and spermatogenesis of male offspring rats. CdCl2 at different doses (0, 0.5, 1, 2 mg/kg/day) were dispensed to pregnant SD rats, thus producing generation F1. Adult females in F1 (PND 56) were mated with untreated fertile males so as to produce generation F2. Likewise, adult females in F2 were mated to produce generation F3. Damages to testicular tissue were observed in all the three generations, with serum testosterone (T) increased in F2 and F3. Notably, the genome-wide DNA methylation level in the testicular tissue of F1 was altered, as was the expression of F1-F3 methyltransferases. In addition, the expression of Creb/Crem pathway, a pathway critical for the metamorphosis from postmeiotic round spermatocytes to spermatozoa, was also remarkably altered in the three generations. In concludion, prenatal Cd exposure might bring multigenerational and transgenerational toxic effects to testes via genome-wide DNA methylation and the regulation of CREB/CREM pathway.

Tembusu virus induced apoptosis in vacuolate spermatogenic cells is mediated by Cytc-mediated mitochondrial apoptotic signaling pathway

Duck Tembusu virus (DTMUV) is an emerging mosquito-borne flavivirus that infects mainly poultry and has caused huge economic losses to the poultry farming industry in China. Also known as duck hemorrhagic ovarian disease, DTMUV principally destroys ovarian tissue in ducks, causing a dramatic drop in egg production. and can also invade the male reproductive system causing lesions. Currently, little research has been done to reveal the underlying mechanisms of reproductive dysfunction in ducks caused by DTMUV infection. In this study, histopathological analysis and electron microscopy of testes of ducks infected with DTMUV showed that DTMUV caused testicular atrophy and cytoplasmic vacuolation in ducks. Terminal Deoxynucleotidyl Transferase-Mediated Nick-End Labeling (TUNEL) staining and real-time quantitative PCR(RT-qPCR) results further indicated that DTMUV induced spermatogenic cells apoptosis. After DTMUV infection, a large amount of cytochrome c(Cytc) was released from the mitochondrial matrix into the cytoplasm, activating downstream target proteins and causing apoptosis. To sum up, DTMUV induces spermatogenic cell apoptosis through the Cytc-induced mitochondrial apoptosis pathway, our study provides evidence for DTMUV infection-induced male reproductive disorders.

The crosstalk between telomeres and DNA repair mechanisms: an overview to mammalian somatic cells, germ cells, and preimplantation embryos

Telomeres are located at the ends of linear chromosomes and play a critical role in maintaining genomic stability by preventing premature activation of DNA repair mechanisms. Because of exposure to various genotoxic agents, telomeres can undergo shortening and genetic changes. In mammalian cells, the basic DNA repair mechanisms, including base excision repair, nucleotide excision repair, double-strand break repair, and mismatch repair, function in repairing potential damages in telomeres. If these damages are not repaired correctly in time, the unfavorable results such as apoptosis, cell cycle arrest, and cancerous transition may occur. During lifespan, mammalian somatic cells, male and female germ cells, and preimplantation embryos experience a number of telomeric damages. Herein, we comprehensively reviewed the crosstalk between telomeres and the DNA repair mechanisms in the somatic cells, germ cells, and embryos. Infertility development resulting from possible defects in this crosstalk is also discussed in the light of existing studies.

Effects of imidacloprid-contaminated feed exposure on spermatogenic cells and Leydig cells in testes of adult male rabbits (Oryctolagus cuniculus)

This research was undertaken to assess the results of repeated exposure to the insecticide; imidacloprid (IMI)-contaminated feed on testicular tissue, spermatogenic cell population, Leydig cell number, and sperm morphology in adult male rabbits (n = 24). The treatment groups received IMI (Bildor® 100 mg/L water spray on green grass)-contaminated green grass without wash (n = 8, not-washed-feed rabbit group) and after wash (n = 8, washed-feed rabbit group) once daily for two weeks on an alternate day basis. The rest of the rabbits, as control, received a normal pesticide-free standard feed. During the exposure time, there was no evident toxic symptom found on regular monitoring of IMI-treated rabbits. Histopathologically, the thickness of tunica albuginea of testes reduced significantly with loosely arranged connective tissues in IMI-treated rabbits. Within the testes, the bizarre-shaped seminiferous tubules were seen with increased lumen diameter in IMI-treated rabbits. The spermatogenic cells were disorganized and detached from the basement membrane in seminiferous tubules of IMI-exposed testes of rabbits. The spermatogenic cell population decreased significantly (P < 0.05) in IMI-treated rabbits compared to control rabbits. Leydig cell number decreased significantly (P < 0.05) in IMI-treated rabbits. A high percentage of morphologically abnormal spermatozoa was seen in IMI-treated rabbits. The degree of the histopathological changes was more prominent in the testes of IMI-exposed not-washed-feed rabbits. The results showed that insecticide-IMI has toxicological effects on testicular tissues, mainly spermatogenic and Leydig cell population of adult rabbits which may cause infertility. A short running title: Effect of imidacloprid on testicular tissue of rabbits.

Exposure to automobile exhaust-derived PM2.5 induces spermatogenesis dysfunction by damaging UPRmt of prepubertal rats

Automobile exhaust-derived particulate matter 2.5 (PM2.5) can cause spermatogenic cell damage, potentially resulting in male infertility. This study uses male prepubertal Sprague Dawley (SD) rats to explore the molecular mechanisms by which automobile exhaust-derived PM2.5 causes spermatogenic cell damage and induces spermatogenesis dysfunction during sexual maturity by disrupting the mitochondrial unfolded protein response (UPR^mt) in spermatogenic cells. Male prepubertal SD rats were randomly divided into four groups: control (intratracheal instillation of normal saline), low-dose PM2.5 (5 mg/kg), high-dose PM2.5 (10 mg/kg), and PM2.5 10 mg/kg +Vit (100 mg/kg of vitamin C and 50 mg/kg of vitamin E). The rats were treated for four weeks, with five consecutive treatment days and two non-treatment days, followed by cohabitation. Testicular and epididymal tissues were harvested for analysis. The mitochondria in spermatogenic cells were observed under an electron microscope. UPR^mt-, oxidative stress-, and apoptosis-related markers in spermatogenic cells were examined. Spermatogenic cell numbers and conception rate declined significantly with increasing PM2.5 dose, with their mitochondria becoming vacuolated, swollen, and degenerated to varying degrees. The apoptosis of spermatogenic cells was abnormally enhanced in PM2.5 exposed groups compared to the control group. Spermatogenic cell numbers of conception rate gradually recovered, mitochondrial damage in spermatogenic cells was alleviated, and spermatogenic cell apoptosis was significantly reduced after vitamin intervention. In addition, protein levels of superoxide dismutase 1 (Sod1), nuclear factor erythroid 2-related factor 2 (Nrf2), and B-cell lymphoma 2 (Bcl-2) were significantly lower, while those of Bcl2-associated X apoptosis regulator (Bax), cleaved caspase 3 (Casp3), and cytochrome c (Cyt-c) and malondialdehyde (MDA) levels were significantly higher in the high-dose PM2.5 group than in the control group. The levels of UPR^mt-related proteins C/EBP homologous protein (Chop), heat shock protein 60 (Hsp60), and activating transcription factors 4 (Atf4) and 5 (Atf5) were higher in the low-dose PM2.5 group, lower in the high-dose PM2.5 group, and gradually recovered in PM2.5 10 mg/kg +Vit group. Our results show that exposure to automobile exhaust-derived PM2.5 induces oxidative stress responses, leads to post-sexual maturation UPR^mt dysfunction and mitochondrial impairment, and abnormally enhances spermatogenic cell apoptosis in prepubertal rats, resulting in male infertility.

Quantitative evaluation of spermatogenesis by fluorescent histochemistry

Identifying the types of spermatogenic cells that compose seminiferous tubules, as well as qualitative confirmation of the presence or absence of disorders, has been regarded as crucial in spermatogenesis. Sperm count and fertilizing capacity, both of which depend on the quality as well as quantity of spermatogenesis, are factors critical to fertilization. However, the quantitative assessment of spermatogenesis is not commonly practiced. Spermatogenesis has species-specific stages; when the specific stage in the seminiferous tubules is precisely determined, the types of spermatogenic cells in each stage can be spontaneously identified. Thereafter, a unique marker is used to classify the cells observed in each stage. Quantitative assessment of spermatogenesis has the potential to detect inapparent spermatogenesis disorders or numerically indicate the degree of the disorder. To this end, a histochemical approach using unique markers is indispensable for the quantitative assessment of spermatogenesis. Future developments in techniques to measure cell populations using computer software will further facilitate the establishment of quantitative assessment of spermatogenesis as a standard analysis method that can contribute significantly to advance our understanding of spermatogenesis.

Structural observations on spermatogenic cells of Japanese quail (Coturnix coturnix japonica) pre-pubertally exposed to dibutyl phthalate: A light and transmission electron microscopy study

Exposure to dibutyl phthalate (DBP) induces testicular damage in mammals. However, studies on the effects of DBP on spermatogenic cells in birds are grossly lacking. Therefore, this study was designed to determine the effects of the pre-pubertal exposure to DBP on the histology and ultrastructure of spermatogenic cells in the testis of adult Japanese quail (Coturnix coturnix japonica). The birds were randomly divided into five dosage groups at the age of 4 weeks. The control group received a corn oil vehicle only (a dose of 1 mL/kg body weight), while the other four experimental groups received a daily dosage of 10, 50, 200, 400 mg/kg body weight of DBP (dissolved in corn oil), respectively with the aid of gastric lavage, for 30 days. Testicular samples were processed and examined by light microscopy and transmission electron microscopy. Histopathological evaluation revealed vacuole formation, germ cell degenerations, and the absence of spermatogenic cell series. Ultrastructurally, chromatin clumps in spermatocyte and degenerated spermatogonia with ruptured nuclear membranes resting on the distorted basement membranes were observed. Others were intracytoplasmic vacuoles in round spermatids and fragments of dense apoptotic bodies. In conclusion, the findings of the present study reveal that spermatogenic cells of Japanese quails seem to be more sensitive to DBP-induced degeneration compared to mammalian species studied. The Japanese quail could be used to monitor environmental contamination with low doses of DBP.

VASA-induced cytoplasmic localization of CYTB-positive mitochondrial substance occurs by destructive and nondestructive mitochondrial effusion, respectively, in early and late spermatogenic cells of the Manila clam

To analyze the release of mitochondrial material, a process that is believed to be (i) induced by the VASA protein derived from germplasm granules, and (ii) which appears to play an important role during meiotic differentiation, the localization of the CYTB protein was studied in the process of spermatogenesis of the bivalve mollusk Ruditapes philippinarum (Manila clam). It was found that in early spermatogenic cells, such as spermatogonia and spermatocytes, the CYTB protein shows dispersion in the cytoplasm following the total disaggregation of VASA-invaded mitochondria, what is called here as "destructive mitochondrial effusion (DME)." It was found that the mitochondria of the maturing sperm cells also uptake VASA. It is accompanied by extramitochondrial transmembrane localization of CYTB assuming mitochondrial content release without mitochondrion demolishing. This phenomenon is called here as "nondestructive mitochondrial effusion (NDME)." Thus, in the spermatogenesis of the Manila clam, two patterns of mitochondrial release, DME and NDME, were found, which function, respectively, in early spermatogenic cells and in maturing spermatozoa. Despite the morphological difference, it is assumed that both DME and NDME have a similar functional nature. In both cases, the intramitochondrial localization of VASA coincides with the extramitochondrial localization of the mitochondrial matrix.

Sub-fertility in crossbred bulls: Identification of proteomic alterations in spermatogenic cells using high throughput comparative proteomics approach

The present study was carried out to compare the proteomic profiles of spermatogenic cells of crossbred and zebu cattle in an effort to understand the possible reasons for a higher incidence of sub-fertility in crossbred bulls. The spermatogenic cells collected from the testes of pre-pubertal (6 mo) and adult (24 mo) crossbred and zebu males through fine needle aspiration were proliferated in vitro, and proteomic profiling was done using a shotgun proteomics approach. The age- and species-specific variations in the expression level of proteins were identified in spermatogenic cells. The number of differentially expressed proteins (DEPs) identified in pre-pubertal zebu and crossbred was 546, while 579 DEPs were identified between adult zebu and crossbred bulls. Out of these, 194 DEPS were common to these groups and 40 DEPs displayed a fold change ≥2. However, only 20 proteins exhibited similar expression variation trends (upregulated or downregulated) among pre-pubertal as well as adult zebu and crossbred bulls. Out of these 20 DEPs, 13 proteins were upregulated, and 7 proteins were downregulated in spermatogenic cells of zebu compared to crossbred bulls. Among the upregulated proteins were RPLP2, PAXIP1, calumenin, prosaposin, GTF2F1, TMP2, ubiquitin conjugation factor E4A, COL1A2, vimentin, protein FAM13A, peripherin, GFPT2, and GRP78. Seven proteins that were downregulated in zebu bulls compared to crossbred included APOA1, G patch domain-containing protein 1, NAD P transhydrogenase mitochondrial, glutamyl aminopeptidase, synaptojanin 1 fragment, Arf GAP with SH3 domain ANK repeat and PH domain-containing protein 1, and protein transport protein sec16B. It was inferred that the proteins associated with sperm function and fertilization processes, such as calumenin, prosaposin, vimentin, GRP78, and APOA1 could be studied further to understand the precise cause of subfertility in crossbred bulls.

CAG repeat instability in embryonic stem cells and derivative spermatogenic cells of transgenic Huntington's disease monkey

PURPOSE

The expansion of CAG (glutamine; Q) trinucleotide repeats (TNRs) predominantly occurs through male lineage in Huntington's disease (HD). As a result, offspring will have larger CAG repeats compared to their fathers, which causes an earlier onset of the disease called genetic anticipation. This study aims to develop a novel in vitro model to replicate CAG repeat instability in early spermatogenesis and demonstrate the biological process of genetic anticipation by using the HD stem cell model for the first time.

METHODS

HD rhesus monkey embryonic stem cells (rESCs) were cultured in vitro for an extended period. Male rESCs were used to derive spermatogenic cells in vitro with a 10-day differentiation. The assessment of CAG repeat instability was performed by GeneScan and curve fit analysis.

RESULTS

Spermatogenic cells derived from rESCs exhibit progressive expansion of CAG repeats with high daily expansion rates compared to the extended culture of rESCs. The expansion of CAG repeats is cell type-specific and size-dependent.

CONCLUSIONS

Here, we report a novel stem cell model that replicates genome instability and CAG repeat expansion in in vitro derived HD monkey spermatogenic cells. The in vitro spermatogenic cell model opens a new opportunity for studying TNR instability and the underlying mechanism of genetic anticipation, not only in HD but also in other TNR diseases.

Protein expression pattern of calcium-responsive transactivator in early postnatal and adult testes

Calcium-responsive transactivator (CREST), a nuclear protein highly expressed in postmitotic neurons, is involved in the regulation of cell cycle, differentiation and dendritic development of neuronal cells. Its mRNA has been detected in the testis of adult rat, whilst its protein expression and distribution pattern in the testis remain to be elucidated. In this study, we examined the distribution of CREST in the adult testes of both rats and human as well as the expression pattern of CREST in the testes of postnatal developing rats. In the adult testes of both human and rats, immunohistochemical analysis revealed that CREST was selectively distributed in the mature Sertoli cells but not in the spermatogenic cells. In the testes of postnatal developmental rats, CREST was expressed not only in Sertoli cells but also in the gonocytes and spermatogenic cells at the initial stage of spermatogenic cell differentiation. CREST immunoreactivity continued to increase in Sertoli cells during differentiation, reaching its peak in adulthood. However, CREST immunostaining intensity dramatically decreased as the spermatogenic cells differentiate, disappearing in the post-differentiation stage. Furthermore, Brg1 and p300, two CREST-interacting proteins ubiquitously expressed in the body, are found to be colocalized with CREST in the spermatogenic epithelial cells including Sertoli cells. The unique expression pattern of CREST in developing testis suggests that CREST might play regulatory roles in the differentiation of spermatogenic epithelial cells. The Sertoli cell-specific expression of CREST in the adulthood hints that CREST might be a novel biomarker for the mature Sertoli cells.

Effects of HIF-1α on Spermatogenesis of Varicocele Rats by Regulating VEGF/PI3K/Akt Signaling Pathway

Hypoxia-inducible factor-1α (HIF-1α) participates in the regulation of spermatogenic function in rats with varicocele (VC), and the PI3K/Akt pathway plays an important role in it. In the present research, we applied the CRISPR/Cas9 gene editing technique to silence the HIF-1α gene of VC rat testis, to explore the effect of HIF-1α on apoptosis of spermatogenic cells in VC rats through the PI3K/Akt pathway. Sprague Dawley rats were randomly assigned to four groups, including the normal rat group (group N), VC model group (group V), VC + HIF-1α-lentivirus group (group H), and VC + luciferase-lentivirus group (group L). Apoptosis of spermatogenic cells in rat testis was tested by TUNEL Kit. The morphologic changes of seminiferous tubules were viewed by a light microscope. Expressions of VEGF, Akt, p-Akt, p70S6K, and p-p70S6K were detected by means of Western blot, immunofluorescence, or immunohistochemistry methods. One-way ANOVA was applied to analyze the diverseness between groups. Compared with group N, the distribution of germ cells was disordered, apoptosis of spermatogenic cells increased significantly, and the expression of VEGF, p-Akt, and p-p70S6K was also increased in group V. Compared with group V, the damage of seminiferous epithelium in group H was improved, and the arrangement of the seminiferous epithelium was almost orderly. Apoptosis of spermatogenic cells decreased significantly, and the expression of VEGF, p-Akt, and p-p70S6K protein was decreased (P < 0.05). There was no significant difference between group N and group H (P > 0.05).In conclusion, HIF-1α is regulated by hypoxia in rats with varicocele to regulate its downstream gene VEGF which regulates spermatogenesis, and the PI3K/Akt signaling pathway plays a regulatory role in this process.

Human umbilical cord multipotent mesenchymal stromal cells alleviate acute ischemia-reperfusion injury of spermatogenic cells via reducing inflammatory response and oxidative stress

BACKGROUND

This study was designed to determine the effect of human umbilical cord multipotent mesenchymal stromal cells (hUC-MSC) on acute ischemia/reperfusion (I/R) injury of spermatogenic cells.

METHOD

The testicular I/R rat model was established through 720° torsion for 1 h. hUC-MSC were intravenously injected 10 min before detorsion. Injury severity of spermatogenic cells was estimated by Johnsen's score. The proliferating of recipient spermatogonia was measured by the immunostaining of antibodies against Ki67, and all germ cells were detected with DDX4 antibody. And recipient spermatogenesis was assessed by staining spermatozoa with lectin PNA. The levels of inflammatory factors were measured by real-time PCR. And the Selectin-E expression, neutrophil infiltration in the testes was detected by immunostaining. Germ cells apoptosis was tested by TUNEL assay and western blot. Furthermore, the oxidative stress was tested by reactive oxidative species (ROS) levels. In vitro, the condition medium (CM) of hUC-MSC was used to culture human umbilical vein endothelial cells (HUVECs), so as to assess the paracrine effect of hUC-MSC on HUVECs. The protein chip was used to measure the relative concentration of the secretory proteins in the CM of hUC-MSC.

RESULT

hUC-MSC greatly alleviated the testicular injury induced by testis I/R. The levels of proinflammatory factors were downregulated by hUC-MSC in vivo and in vitro. Neutrophil infiltration, ROS, and germ cell apoptosis in testicular tissues were greatly reduced in the group of hUC-MSC. Paracrine factors secreted by hUC-MSC including growth factors, cytokines, and anti-inflammatory cytokine were rich.

CONCLUSION

This study demonstrated that intravenously injected hUC-MSC could protect the spermatogenic cells against I/R injury by reducing the inflammatory response, apoptosis, and acute oxidative injury. Paracrine mechanism of hUC-MSC may contribute to the protection of spermatogenic cells against I/R injury. Therefore, the present study provides a method for clinical treatment of attenuate I/R injury of spermatogenic cells.

Mechanism of Heshouwuyin inhibiting the Cyt c/Apaf-1/Caspase-9/Caspase-3 pathway in spermatogenic cell apoptosis

BACKGROUND

The Chinese herbal compound Heshouwuyin has been shown to downregulate the apoptotic rate of testicular tissue cells in Wistar naturally aging rats, and this effect might be related to the mitochondrial pathway [15]. Apoptotic protease activating factor-1 (Apaf-1) is a major component of the apoptotic complex, which is a key element of the mitochondrial endogenous apoptotic pathway [13]. To further clarify the mechanism of Heshouwuyin in the mitochondrial apoptotic pathway, this study used Apaf-1 as a target to explore the mechanism by which Heshouwuyin inhibits the Apaf-1 pathway of spermatogenic cell apoptosis.

METHODS

In this study, an aging model of rat spermatogenic cells was established using free radical oxidative damage. Flow cytometry was used to detect the apoptosis rate of germ cells and the inhibitory effect of Heshouwuyin. Apaf-1 was specifically knocked down by siRNA interference technology, and mitochondrial membrane potential was measured. qRT-PCR, Western blotting and immunofluorescence analyses were used to detect the expression of the key genes Cyt c, Caspase-9 and Caspase-3 in the mitochondrial apoptotic pathway of spermatogenic cells.

RESULTS

Heshouwuyin reduced the mRNA and protein expression levels of Cyt c, Caspase-9 and Caspase-3 in senescent spermatogenic cells. In these cells, the mRNA and protein expression levels of Cyt c did not change significantly after specific knockdown of Apaf-1, and the mRNA and protein expression levels of Caspase-9 and Caspase-3 decreased significantly. This finding indicated that knockdown of Apaf-1 could decrease the mRNA and protein expression levels of the downstream pro-apoptotic genes Caspase-9 and Caspase-3. Although Cyt c was an upstream gene of Apaf-1, knockdown of Apaf-1 had no significant effect on Cyt c expression.

CONCLUSION

The inhibition of spermatogenic cell apoptosis by Heshouwuyin was closely related to the Cyt c/Apaf-1/Caspase-9/Caspase-3 pathway. The inhibition of apoptosis by Heshouwuyin not only involved the Apaf-1 pathway, but other signaling pathways.

Ultrastructural feature of spermatogenic cells and spermatozoon in cultured burbot Lota lota

Testis development and ultrastructure of spermatogenic cells and spermatozoa of burbot Lota lota, a commercially important cold freshwater fish, were studied by light and transmission electron microscopy. Spermatogonia, spermatocytes, spermatids, and spermatozoa are distributed along the seminiferous tubules. Electron-dense bodies appear in germ cells from primary spermatogonia to secondary spermatocytes. We identified three distinct stages of spermatid cell differentiation based on chromatin condensation, development of the flagellum, formation of a nuclear fossa, and elimination of excess cytoplasm. Spermatozoa were anacrosomal and characterized by location of the centrioles outside the nuclear fossa and incomplete perpendicular arrangement of the centrioles. The sperm flagellum displayed an axoneme with nine doublets of peripheral microtubules and two central microtubules. These results provide valuable information for burbot taxonomy and may clarify the process of spermatogenesis for this species.

Aloe arborescens juice prevents EMF-induced oxidative stress and thus protects from pathophysiology in the male reproductive system in vitro

More and more studies suggest that prolonged exposure to EMF may cause adverse biological effects and point directly to a significantly negative correlation between EMF and human health, especially men fertility. In our previous study, we reported that this could be related to the EMF-induced reactive oxygen species formation, followed by DNA damage, cell cycle arrest and apoptosis induction. In this study, we decided to expand our research by the search for substances which would prevent EMF-induced damage in spermatogenic cells. Such an agent seems to be Aloe arborescens Mill. juice, which was shown to possess a wide range of protective properties. The administration of aloe extract helps among others to prevent the formation of free radicals by various biochemical pathways. Therefore, the main aim of our study was to provide a significant knowledge concerning the mechanism involved in the multi-pathway cytoprotective response of aloe juice against EMF. The study was carried out in an in vitro mouse spermatogenesis pathway cell lines (GC-1 spg and GC-2 spd). Our results suggest that the aloe juice has many positive effects, especially for the cellular antioxidant systems by reducing the intracellular reactive oxygen species pool induced by EMF. In consequence, aloe juice prevents DNA damage, cell cycle arrest and therefore the viability and metabolic activity of both cell line tested are preserved. In conclusion, our study provides new insight into the underlying mechanisms through which aloe juice prevents spermatogenic cells from cytotoxic and genotoxic events.

Isolation and characterization of spermatogenic cells from cattle, yak and cattleyak

Cattleyak forms the first generation in the cross-breeding of cattle (Bos taurus) and yak (Bos grunniens), the purpose of which is to increase the yak's performance in meat and milk production. The female cattleyak is fertile while the male remains sterile due to spermatogenic arrest. The spermatogenic cells (including spermatogonia and spermatocytes) of cattle, yak and cattleyak have not been successfully isolated so far. In this work, spermatogenic cells were isolated from these bovid species with the STA-PUT method that has been previously used for germ cell sorting in human and mouse, and the isolated cells could be used to investigate the mechanisms involved in male sterility observed in cattleyak. The characteristics and size of the isolated cells were investigated through microscopic examination, and the cell types were identified by RT-PCR amplification of the marker genes. The purity of spermatogonia and spermatocytes isolated from each bovid species was found to be higher than 85%. The spermatogonium diameter of cattle (10.10 ± 1.04 μm) and yak (14.90 ± 2.30 μm) were significantly larger (P < 0.01) than that of cattleyak (8.60 ± 0.92 μm). The spermatocyte diameter of cattle (19.40 ± 1.50 μm) and yak (20.50 ± 2.42 μm) were also significantly larger (P < 0.01) than that of cattleyak (17.70 ± 2.05 μm). Therefore, the STA-PUT was again validated to be a convenient, economical and efficient method for isolation of spermatogenic cells as it yields more cells within a short time frame.

Progress on the study of the mechanism of busulfan cytotoxicity

The preparation of spermatogonial stem cell (SSC) transplant recipients laid the technical foundation for SSC transplant technology and the understanding of spermatogenesis mechanisms. Busulfan is commonly used to prepare recipients for mouse SSC transplantation; however, its safety and efficiency have been questioned. This review summarizes the relationship between SSCs and Sertoli cells (SCs), and the mechanism of busulfan toxicity against sperm cells. We concluded that the proliferation, differentiation, and apoptosis of SSCs are regulated by SCs. The endogenous spermatogenic cells are depleted by busulfan treatment via alkylation of DNA, destruction of vimentin filament distribution, disruption of SSC differentiation, promotion of SSC dormancy, and generation of oxidative stress. However, the mechanisms require further exploration. The recent establishment of a model in vitro culture system has provided a good technical foundation to further explore these mechanisms, which will help us to find more efficient methods of recipient preparation and optimal transplantation times.

Detection of phase specificity of in vivo germ cell mutagens in an in vitro germ cell system

In vivo tests for male reproductive genotoxicity are time consuming, resource-intensive and their use should be minimised according to the principles of the 3Rs. Accordingly, we investigated the effects in vitro, of a variety of known, phase-specific germ cell mutagens, i.e., pre-meiotic, meiotic, and post-meiotic genotoxins, on rat spermatogenic cell types separated using Staput unit-gravity velocity sedimentation, evaluating DNA damage using the Comet assay. N-ethyl-N-nitrosourea (ENU), N-methyl-N-nitrosourea (MNU) (spermatogenic phase), 6-mercaptopurine (6-MP) and 5-bromo-2'-deoxy-uridine (5-BrdU) (meiotic phase), methyl methanesulphonate (MMS) and ethyl methanesulphonate (EMS) (post-meiotic phase) were selected for use as they are potent male rodent, germ cell mutagens in vivo. DNA damage was detected directly using the Comet assay and indirectly using the TUNEL assay. Treatment of the isolated cells with ENU and MNU produced the greatest concentration-related increase in DNA damage in spermatogonia. Spermatocytes were most sensitive to 6-MP and 5-BrdU while spermatids were particularly susceptible to MMS and EMS. Increases were found when measuring both Olive tail moment (OTM) and% tail DNA, but the greatest changes were in OTM. Parallel results were found with the TUNEL assay, which showed highly significant, concentration dependent effects of all these genotoxins on spermatogonia, spermatocytes and spermatids in the same way as for DNA damage. The specific effects of these chemicals on different germ cell types matches those produced in vivo. This approach therefore shows potential for use in the detection of male germ cell genotoxicity and could contribute to the reduction of the use of animals in such toxicity assays.

Mitochondrion-mediated apoptosis is involved in reproductive damage caused by BPA in male rats

Bisphenol A (BPA) is a widely used environmental endocrine disruptor. Many studies have reported that BPA exposure shows reproductive toxicity and causes apoptosis in spermatogenic cells. However, few studies have investigated the relationship between the mitochondrial pathway and BPA-induced apoptosis. This study investigated the role of the mitochondrial pathway in apoptosis induced by BPA, which resulted in compromised male rat spermatogenesis and reproductive damage. Rats were exposed to various BPA concentrations (0, 50, 100, or 200mg of BPA/kg body weight per day), and factors in the mitochondrial signal transduction pathway and the apoptosis indices of spermatogenic cells were measured and sperm characteristics were analyzed. Our data revealed that BPA exposure increased the protein and mRNA levels of cytochrome C, apoptosis-inducing factor, caspase-3/9, and Bax; caspase-3 and caspase-9 activities; and the apoptosis indices of spermatogenic cells. In addition, abnormal structure of mitochondria and decreased protein and gene levels of Bcl-2 were observed following BPA exposure. These results suggest that apoptosis in the mitochondrial pathway mediates compromised reproductive system function caused by BPA exposure.

Morphological evaluation of spermatogenesis in Lake Magadi tilapia (Alcolapia grahami): a fish living on the edge

Spermatogenesis in Lake Magadi tilapia (Alcolapia grahami), a cichlid fish endemic to the highly alkaline and saline Lake Magadi in Kenya, was evaluated using light and transmission electron microscopy. Spermatogenesis, typified by its three major phases (spermatocytogenesis, meiosis and spermiogenesis), was demonstrated by the presence of maturational spermatogenic cells namely spermatogonia, spermatocytes, spermatids and spermatozoa. Primary spermatogonia, the largest of all the germ cells, underwent a series of mitotic divisions producing primary spermatocytes, which then entered two consecutive meiotic divisions to produce secondary spermatocytes and spermatids. Spermatids, in turn, passed through three structurally distinct developmental stages typical of type-I spermiogenesis to yield typical primitive anacrosomal spermatozoa of the externally fertilizing type (aquasperm). The spermatozoon of this fish exhibited a spheroidal head with the nucleus containing highly electron-dense chromatin globules, a midpiece containing ten ovoid mitochondria arranged in two rows and a flagellum formed by the typical 9 + 2 microtubule axoneme. In addition, the midpiece, with no cytoplasmic sheath, appeared to end blindly distally in a lobe-like pattern around the flagellum; a feature that was unique and considered adaptive for the spermatozoon of this species to the harsh external environment. These observations show that the testis of A. grahami often undergoes active spermatogenesis despite the harsh environmental conditions to which it is exposed on a daily basis within the lake. Further, the spermiogenic features and spermatozoal ultrastructure appear to be characteristic of Cichlidae and, therefore, may be of phylogenetic significance.

The effect of Carbaryl on the pituitary-gonad axis in male rats

BACKGROUND

Carbaryl is a carbamate insecticide widely used to control pests in agriculture and farm. Carbaryl adversely affect the reproductive endocrine systems in animals.

OBJECTIVE

The aim of this study was to evaluate Carbaryl effects on the pituitary-gonad axis in rats.

MATERIALS AND METHODS

In this experimental - analytical study, 60 adult male rats were divided into four equal groups: control, sham and experimental (1 and 2) groups that received 10 and 30 mg/kg Carbaryl via intraperitoneally injection. The sham group was subjected to intraperitoneally injection with olive oil while the control group did not receive any injection. Animals were sacrificed 35 days after the last treatment. Tissue sections were prepared from testes to investigate possible changes occurring in spermatogenic and Leydig cells. Blood samples were collected in which the levels of testosterone, luteinizing hormones (LH) and follicle stimulating hormone (FSH) were measured.

RESULTS

The results showed significant reduction in testes weight (p=0.042) and seminiferous diameters (p<0.001) within the experimental groups compared with control group. Also, the number of germ cells, spermatocyts, spermatids and Leydig cells on the testes of the experimental groups was significantly decreased (p<0.001). Accordingly, significant decline in the testosterone levels (p<0.001) and increase in LH and FSH levels were observed (p<0.05).

CONCLUSION

These results demonstrated that Carbaryl has capacity to exert adverse effects on fertility. Therefore, have to be taken to account in applying Carbaryl for any studies and or commercial use.