Intrauterine exposure to 2,3',4,4',5-pentachlorobiphenyl alters spermatogenesis and testicular DNA methylation levels in F1 male mice.

Polychlorinated biphenyls (PCBs) are synthetic biphenyl compounds with high toxicity. There are a total of 209 homologs, among which 2,3',4,4',5-pentachlorobiphenyl (PCB118) is one of the dioxin-like PCBs. PCB118 can accumulate in pregnant mice, leading to fetus directly exposure during development. The stage of migration of mouse primordial germ cells ranges from 8.5 to 13.5 days of pregnancy, which is the stage undergoing a genome-wide DNA demethylation process. In this study, the mice were exposed to 20 µg/kg/day and 100 µg/kg/day PCB118 from 8.5 to 13.5 days of pregnancy. During the embryo stage at 18.5 days (E18.5 days), the expression level of DNA methyltransferase 1 (Dnmt1) was reduced in the testes, and the DNA methylation level in mouse testes were also decreased. We found that the seminiferous tubules showed vacuolization and that the sperm deformity rate increased in the treated groups compared with the control group in 7-week-old mice. Because exposure to PCB118 during pregnancy causes damage to the reproductive system of male offspring mice, attention should be devoted to the toxicity transmission of persistent environmental pollutants such as PCBs.

[Effects of Vitrification with Self-made Carriers and Slow Programmed Freezing on Ovarian Tissue of Sheep].

Objective To investigate the effects of self-made carriers on the cryopreservation of ovarian tissue of sheep. Methods Thirty-two ovaries were randomly assigned to fresh group,programmed freezing group,self-made carrier I vitrification group,and self-made carrier Ⅱ vitrification group.The morphology,proliferation,apoptosis,and estrogen level of the ovarian tissue in each group were observed. Results After cryopreservation,the morphology normal rate of the primordial follicles in programmed freezing group,self-made carrier I vitrification group,and self-made carrier Ⅱ vitrification group were 74.2%,72.8%,and 72.3%,respectively,lower than that(83.7%)in the fresh group(χ2=13.079,P=0.004).The percentage of normal primary follicles in programmed freezing group was lower than that in the fresh group(χ2=12.486,P=0.000).The percentage of normal primary follicles showed no significant difference between vitrification groups and fresh group(P=1.000,P=0.972).There was no significant difference in estrogen level or the positive expression rate of PCNA among the 4 groups(F=0.363,P=0.780;χ2=0.359,P=0.949).The number of apoptotic cells in cryopreservation groups was significantly higher than that in the fresh group(F=37.584,P=0.000),and it was significantly higher in the programmed freezing group than in the two vitrification groups(F=18.992,P=0.000). Conclusion Compared with slow programmed freezing,the vitrification with self-made carriers could well preserve the activity of cells in large sheep ovarian tissue blocks.

Effects of intrauterine exposure to 2,3',4,4',5-pentachlorobiphenyl on the reproductive system and sperm epigenetic imprinting of male offspring.

Polychlorinated biphenyls (PCBs) are a class of persistent organic environmental pollutants with a total of 209 homologs. The homolog 2,3',4,4',5-pentachlorobiphenyl (PCB118) is one of the most important dioxin-like PCBs and is highly toxic. PCB118 can accumulate in human tissues, serum and breast milk, which leads to direct exposure of the fetus during development. In the present study, pregnant mice were exposed to 0, 20 and 100 µg/kg/day of PCB118 during the stage of fetal primordial germ cell migration. Compared with the control group, we found morphological alterations of the seminiferous tubules and a higher sperm deformity rate in the male offspring in the treatment groups. Furthermore, the methylation patterns in the treatment groups of the imprinted genes H19 and Gtl2 in the sperm were altered in the male offspring. We also characterized the disturbance of the expression levels of DNA methyltransferase 1 (Dnmt1), Dnmt3a, Dnmt3b, Dnmt3l, and Uhrf1. The results indicated that intrauterine exposure to low doses of PCB118 could significantly damage the reproductive health of the male offspring. Therefore, attention should be paid to the adverse effects of PCB118 exposure during pregnancy on the reproductive system of male offspring.

Activated proline-rich tyrosine kinase 2 regulates meiotic spindle assembly in the mouse oocyte.

Proline-rich tyrosine kinase 2 (PYK2), a member of the protein tyrosine kinase family, plays an important role in various cellular processes. PYK2 can be phosphorylated on tyrosine 402 by diverse stimuli at the cell surface, and recent studies have shown that this activated form of PYK2 is enriched in oocytes and required for fertilization. However, the subcellular localization and functions of activated PYK2 in oocytes remain elusive. In this study, we demonstrate that the localization of p-PYK2 undergoes dynamic changes during in vitro maturation of mouse oocytes. The signal of p-PYK2 is initially dispersed in the cytoplasm, but begins to decorate organized microtubules after the germinal vesicle breakdown and localizes to spindle poles at metaphase. Our data further show that p-PYK2 colocalizes with γ-tubulin from the germinal vesicle stage through the end of meiosis in mouse oocytes. Nocodazole treatment and washout experiments confirm that p-PYK2 associates with the oocyte spindle and spindle poles. Moreover, pharmacological inhibition of PYK2 activity dramatically alters the morphology of the bipolar spindle and prevents oocyte maturation. Together, these data suggest that activated PYK2 may function as a component of the microtubule organizing center to regulate spindle assembly during the meiotic process of mouse oocytes.

Analysis of retinal arteriolar and venular parameters in primary open angle glaucoma.

AIM: To measure the retinal vessels of primary open angle glaucoma (POAG) patients on spectral domain optical coherence tomography (SD-OCT) with a full-width at half-maximum (FWHM) algorithm to better explore their structural changes in the pathogenesis of POAG. METHODS: In this retrospective case-control study, the right eyes of 32 patients with POAG and 30 healthy individuals were routinely selected. Images of the supratemporal and infratemporal retinal vessels in the B zones were obtained by SD-OCT, and the edges of the vessels were identified by the FWHM method. The internal and external diameters, wall thickness (WT), wall cross-sectional area (WCSA) and wall-to-lumen ratio (WLR) of the blood vessels were studied. RESULTS: Compared with the healthy control group, the POAG group showed a significantly reduced retinal arteriolar outer diameter (RAOD), retinal arteriolar lumen diameter (RALD) and WSCA in the supratemporal (124.22±12.42 vs 138.32±10.73 µm, 96.09±11.09 vs 108.53±9.89 µm, and 4762.02±913.51 vs 5785.75±1148.28 µm2, respectively, all P<0.05) and infratemporal regions (125.01±15.55 vs 141.57±10.77 µm, 96.27±13.29 vs 110.83±10.99 µm, and 4925.56±1302.88 vs 6087.78±1061.55 µm2, all P<0.05). The arteriolar WT and WLR were not significantly different between the POAG and control groups, nor were the retinal venular outer diameter (RVOD), retinal venular lumen diameter (RVLD) or venular WT in the supratemporal or infratemporal region. There was a positive correlation between the arteriolar parameters and visual function. CONCLUSION: In POAG, narrowing of the supratemporal and infratemporal arterioles and a significant reduction in the WSCA is observed, while the arteriolar WT and WLR do not change. Among the venular parameters, the external diameter, internal diameter, WT, WLR, and WSCA of the venules are not affected.

Author Correction: A full-width half-maximum method to assess retinal vascular structural changes in patients with ischemic heart disease and microvascular angina.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A full-width half-maximum method to assess retinal vascular structural changes in patients with ischemic heart disease and microvascular anginga.

Chest pain patients without obstructive ischemic heart disease (IHD) have increased attention in the clinical practice as carrying higher cardiovascular (CV) risk and impaired life quality. Retinal vasculature is a novel but reliable risk factor of atherosclerosis and systemic vascular diseases. However, the association of retinal blood vessels and unobstructed IHD, as known as microvascular anginga (MA) is poorly understood. This study compared retinal vascular structures of obstructive IHD and MA using spectral domain optical coherence tomography (SD-OCT) and full-width half-maximum (FWHM) methods to provide new risk predictive evidence of MA. Fundus vessels of 120 IHD patients, including 91epicardial IHD and 29 MA patients, and 66 control subjects were evaluated. Significant differences in the retinal arterial lumen diameter (RALD), retinal arterial outer diameter (RAOD), and arteriovenous ratio (AVR) have been found (P < 0.05). The severity of IHD was negatively correlated with diameters of RAOD, RALD and AVR (P < 0.05). In conclusion, there were significant differences in the retinal vascular structure between IHD patients and patients with MA. Thus, assessment of retinal vascular structure is suggested to evaluate CV risk of IHD patients, despite having no obstructive IHD.

Toxic effects of polychlorinated biphenyls (Aroclor 1254) on human sperm motility.

Polychlorinated biphenyls (PCBs) are common environmental contaminants that represent a considerable risk to reproductive toxicity in exposed human populations. Although some experimental studies have suggested an association between the levels of PCBs and semen quality, the direct effects of PCBs on human sperm parameters remain largely unexplored. To this aim, a short-term in vitro incubation experiment that better imitated the putative exposure of sperm to Aroclor 1254 (a commercial PCB mixture) in male reproduction tissue was conducted. Human sperm were incubated with various concentrations (0, 1, 5, or 25 mg l-1) of Aroclor 1254 for different amounts of time (3 and 6 h) in vitro. Sperm motility parameters were analyzed with computer-assisted sperm analysis (CASA). The proportion of sperm with high mitochondrial membrane potential (ΔΨm) and the levels of intracellular reactive oxygen species (ROS) were detected to explore the probable cause of sperm impairment. Human sperm exposed to continuous Aroclor 1254 exhibited: (i) reduced sperm motility and kinematic parameters, (ii) a proportion of sperm with high ΔΨm that decreased in a dose-dependent manner (P < 0.05), and (iii) increased levels of ROS compared with controls (P < 0.05). In conclusion, Aroclor 1254 can decrease sperm motility, which may culminate in increased ROS and general mitochondrial dysfunction, thus affecting the fertilization potential of sperm. Our findings suggest a broader understanding of the effect of Aroclor 1254 on human sperm.