El-Sayed A. Mohamed

The transgenerational impact of benzo(a)pyrene on murine male fertility

BACKGROUND Benzo(a)pyrene (BaP) is an endocrine toxicant that is widely distributed in the environment. The adverse effects of BaP on fertility are well documented, however its effects on fertility in the subsequent generations are not known. We aimed to investigate the transgenerational effects of BaP on male fertility in mice. METHODS Six-week-old male mice (F0) were orally administered BaP (1 or 10 mg/kg body weight) or corn oil, daily for 6 weeks. The male mice were mated with untreated female mice to produce F1 offspring. The F2 and F3 progeny were produced in a similar manner. Testes and spermatozoa were collected from 14-week-old F0, F1, F2 and F3 males in order to assess male fertility parameters, namely testis histology, sperm count, sperm motility and sperm penetration (sperm penetration assay). RESULTS Oral administration of a high dose of BaP induced testicular malformation and decreased numbers of seminiferous tubules with elongated spermatids for three generations studied (i.e. F0 to F2) with significant decreases in F0 and F2. It also significantly decreased sperm motility in F0. BaP significantly decreased sperm count in the group treated with a high dose of BaP in all generations except the F3 generation. The sperm fertility index (SFI) also decreased significantly for two generations. Of the fertility parameters measured, sperm count and SFI were the more sensitive parameters in our study. CONCLUSIONS Exposure to BaP decreases the fertilization potential of exposed males and has an adverse impact on sperm function and fertility in subsequent generations. The BaP effect on fertility can be described as a transgenerational effect for F2 generation.

Voltage-dependent anion channels are a key factor of male fertility

OBJECTIVE To examine how voltage-dependent anion channels (VDACs) regulate sperm function in capacitation conditions. DESIGN Experimental prospective study. SETTING Academic research laboratory. ANIMAL(S) Male ICR and female B6D2F1/CrljOri mice (8-12 weeks old). INTERVENTION(S) Female mice were superovulated with 5 IU of pregnant mare serum gonadotropin given IP and 5 IU of hCG given IP 48 hours later. Oocytes were applied to assess fertilization and embryo development. MAIN OUTCOME MEASURE(S) Immunofluorescence assay, computer-assisted sperm analysis, hypo-osmotic swelling test, combined Hoechst 33258/chlortetracycline fluorescence assessment of capacitation status, measurement of [Ca(2+)](i) and [pH](i), Western blotting, and IVF. RESULT(S) VDAC2 was localized on the acrosomal region and principal piece, while VDAC3 was localized on the acrosomal region and midpiece. Blocking VDAC with DIDS (500 μM) significantly decreased motility, viability, acrosome reaction, capacitation, tyrosine phosphorylation, fertilization, and embryo development regardless of Ca(2+). However, the most severe decreases were observed in the presence (+) of DIDS and absence (-) of Ca(2+), respectively. A significant decrease in [Ca(2+)](i) concentration was observed in (-) DIDS, while [pH](i) was significantly increased in (-) DIDS regardless of Ca(2+). However, a significantly elevated [pH](i) was observed in (+) Ca(2+). CONCLUSION(S) Abnormal regulation of VDACs negatively affected sperm function. Thus, VDACs may be key regulators of the fertilization ability of spermatozoa.

Capacitation status of stored boar spermatozoa is related to litter size of sows.

Semen parameters can be considered useful predictors of sperm fertility. The objective of this study was to address the question of whether differences in in vivo fertility after the use of different ejaculates could be predicted using sperm kinematics, capacitation status, and sperm penetration ability under commercial pig production conditions. The percentage of capacitated sperm, as assessed by chlortetracycline (CTC) staining, was positively correlated with litter size (p<0.01). Our data suggest that litter size increases in proportion to the number of capacitated spermatozoa. When all semen parameters (kinematics, sperm capacitation status, and sperm penetration ability) and litter size were included in a multiple linear regression analysis, significant associations were found between the percentage of capacitated sperm (B-type), the sperm fertility index as assessed by a sperm penetration assay (SPA), and litter size. This relationship between capacitated sperm and litter size, however, was more predictive for smaller litter groups than larger ones. We found that the percentage of B-type sperm was significantly correlated with historic average litter size. However, there was no significant correlation between the percentage of B-type sperm and historic farrowing rates. To determine the normal range for B-type sperm, the lower limits were established as 30% for small litters (<8 piglets) and 35% for large litters. The overall accuracy of the assay was 92% and 83% for small and large litters, respectively. These results indicate that capacitation status as measured by CTC staining is a useful predictor of sperm fertility, equivalent to SPA. Moreover, original capacitation status exhibited better predictive ability for small litters than for large ones. Therefore, subfertile boars can be identified primarily by capacitation status.

Xenoestrogenic compounds promote capacitation and an acrosome reaction in porcine sperm

There is growing evidence that endocrine disruptors bind to hormone receptors; since these receptors are present on the sperm membrane, sperm are potentially a useful model for examining estrogenic activities of endocrine disruptors. The objective of the present study was to compare the effects of two xenoestrogenic compounds (genistein and 4-tert-octylphenol) to those of two steroids (estrogen and progesterone) and heparin on in vitro capacitation and the acrosome reaction in a porcine sperm model. Porcine sperm were incubated with various concentrations (0.001-100 μM) of each chemical for 15 or 30 min, and then capacitation and the acrosome reaction were assessed using chlortetracycline. Estrogen and progesterone were considerably more potent than the other chemicals in stimulating capacitation. Estrogen stimulated sperm capacitation at all tested concentrations after 15 min of incubation (P < 0.05), whereas progesterone stimulated sperm capacitation at all tested concentrations after 15 and 30 min (P < 0.05). The effect of genistein on sperm capacitation was comparable with that of estrogen, and it was the most potent in stimulating the acrosome reaction. Genistein stimulated the acrosome reaction at all tested concentrations after 30 min (P < 0.05). However, 4-tert-octylphenol had the least effect on capacitation and the acrosome reaction. In summary, since all chemicals studied effectively altered capacitation and the acrosome reaction, it was concluded that porcine sperm could be a useful model for in vitro screening of potential endocrine disruptors. It was noteworthy that concurrent comparisons to steroids increased the ability to determine estrogenic characteristics of the tested chemicals.

Xenoestrogenic chemicals effectively alter sperm functional behavior in mice

Xenoestrogenic compounds (XCs) can disrupt endogenous hormone function and affect sperm function by binding to receptors on sperm membrane. Albeit spermatozoa are potentially a useful model for screening estrogenic activities of endocrine disruptors, high-quality in vitro test system that examination of the XCs effects on sperm function is required. The objective of this study was to compare the effects of XCs (genistein and 4-tert-octylphenol) to those of steroids (estrogen and progesterone) and heparin on in vitro capacitation and acrosome reaction (AR) in mouse spermatozoa. Mouse spermatozoa were incubated with various concentrations (0.001-100 μM) of each chemical for 15 or 30 min, and then capacitation and AR were assessed using chlortetracycline. All chemicals studied effectively alter capacitation and/or AR in mouse spermatozoa with different manner. Therefore, we believed that our system will provide a good in vitro model system to characterize the physiological effect of XCs especially when compared with steroids.

Significant association of TNFα and IL-6 gene with male infertility--an explorative study in Indian populations of Uttar Pradesh.

In this study were aimed to identify the association of SNPs candidate genes of TNF-α and IL-6 with hormones levels and sperm cells death in infertile subjects of Uttar Pradesh population in North India. The study population comprised, fertile donor (control group) and infertile group patients i.e. normozoospermic (idiopathic unexplained), oligozoospermic and asthenozoospermic groups, with 260 subjects in each group. Subjects were selected from the Departments of Urology, K.Gs Medical University and Urology, SGPGIMS, Lucknow, India. The allele-specific polymerase chain reaction (PCR) and PCR-RFLP were used to investigate the substitution of the guanine (G)-to-adenosine (A) at position-308 and guanine (G)-to-cytosine (C) at position-174 in the promoter regions of the TNF-α and IL-6 genes, respectively. Further their relation to male fertility and sperm function were also investigated. It was found that the substitution levels from G to A and from G to C in the TNF-α and IL-6 genes, respectively, were significantly higher in the infertile subjects as compared to that of control group. The apoptosis and necrosis levels were also higher in oligozoospermic and asthenozoospermic infertile subjects. Further it was found to be associated with increased level of reactive oxygen species as observed in oligozoospermic and asthenozoospermic subjects. However, a significant decrease in testosterone and luteinizing hormone with increased prolactin and follicle stimulating hormones was observed in infertile subjects. The study populations indicating a strong association between TNF-α G-308A and IL-6 G-174C substitution with infertile men which is further supported by allele and genotype meta-analysis and thus established it as a risk factor.

Molecular Characterization of Degrades a Mixture of Low and High Molecular Weight Polycyclic Aromatic Hydrocarbons

RESEARCH ARTICLE Molecular Characterization of Fusarium Solani Degrades a Mixture of Low and High Molecular Weight Polycyclic Aromatic Hydrocarbons Abd El-Latif Hesham, Elsayed A. Mohamed, Asmaa M.M. Mawad, Ameer Elfarash, Bahaa S. Abd El-Fattah and Mahmoud A. El-Rawy Genetics Department, Faculty of Agriculture, Assiut University, Assiut, Egypt Botany and Microbiology, Faculty of Science, Assiut University, 71516, Assiut, Egypt

2,3,7,8-Tetrachlorodibenzo-p-dioxin can alter the sex ratio of embryos with decreased viability of Y spermatozoa in mice

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a reproductive and developmental toxicant that can alter the sex ratio of offspring (proportion of male offspring). We hypothesized that the alteration of sex ratio is associated with sex chromosome ratio of live spermatozoa affected by exposure to TCDD. After exposure to TCDD we analyzed simultaneously sperm sex chromosome constitution and viability, and evaluated sperm sex chromosome ratio association with embryo sex ratio in mice. Short-term exposure to TCDD affects the decreased sperm motility and viability, and the increased acrosome reaction. Interestingly, Y spermatozoa survived shorter than X spermatozoa at high concentrations of TCDD. Moreover, the decreased sex ratio of embryos was associated with the short lifespan of Y spermatozoa. Our results suggest that TCDD may affect the fertility of Y spermatozoa more than X spermatozoa. Further studies are needed to compare the difference of fertilizing capability between X and Y spermatozoa by the effect of TCDD.

Effect of endocrine disruptors on the ratio of X and Y chromosome-bearing live spermatozoa

Although equal numbers of X and Y spermatozoa are produced during spermatogenesis, the sex chromosome ratio in ejaculated spermatozoa can be altered by exposure to endocrine-disrupting chemicals (EDCs), which can be reflected by altered sex ratios at birth. Here, we hypothesized EDCs affect sperm functions and viability of X and Y chromosome-bearing human spermatozoa. After exposure to genistein (Gen), bisphenol A (BPA), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), dibromochloropropane (DBCP), and diazinon (Diaz), we evaluated motility, viability, capacitation, and differential viability of X and Y spermatozoa. All EDCs tested altered sperm viability, motility, and capacitation. Interestingly, the Y/X ratio of live spermatozoa was significantly lower in sperm treated with TCDD, DBCP, and Diaz than control spermatozoa. Our results suggest that some of EDCs have larger effects on the viability of Y spermatozoa than X spermatozoa, implicating that a reduction in Y sperm viability may result in a female-biased sex ratio of offspring at birth.

Evaluating interspecific wheat hybrids based on heat and drought stress tolerance

Three durum and three bread wheat genotypes were crossed to produce three tetraploid, three hexaploid and nine interspecific (pentaploid) F1 hybrids. All genotypes were evaluated for heat tolerance in the field and for drought using polyethylene glycol in vitro. Chromosome numbers and meiotic behavior in pentaploid F1 hybrids (2n=5x=35, genomes AABBD) were confirmed. Heat stress significantly reduced grain yield/plant and 1000-kernel weight (1000-KW), while grain protein content (GPC) was increased. Drought caused a significant reduction in root length, shoot length and seedling fresh weight, whereas root/shoot ratio was increased. P3 (durum), P4 (bread) and their pentaploid F1 hybrid could be considered as the most heat-tolerant genotypes. However, P2 (durum), P6 (bread) and their F1 were most tolerant to drought. The addition of a D genome single dose into pentaploid F1 hybrids obviously reduced grain yield/plant, 1000-KW and seedling traits, however GPC was increased. Moderate to high broad-sense heritability and genetic advance were obtained for the most investigated traits. Grain yield/plant was strongly positively correlated with stress tolerance index (STI), yield index (YI), mean productivity (MP), geometric mean productivity (GMP) and harmonic mean (HM) under heat stress and with root length under drought condition, suggesting that STI, YI, MP, GMP and HM are powerful indices for heat tolerance, while root length is most effective for drought. Successful interspecific hybridization obtained in the study is only an initial step for desired genes introgression. Successive progenies are going to be evaluated for further genetic studies aiming at improving abiotic stress tolerance in wheat.