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Objective: To construct a directional differentiation model from mouse embryonic stem cells into leydig-like cells in vitro., Methods: Mouse ES-D3 cells were transfected with plasmid containing steroidogenic factor 1 (SF-1) gene, then treated with RA and 8Br-cAMP, while the cells transfected with empty plasmid were used as the negative controls. The morphology of leydig-like cells differentiated from ES-D3 cells was observed with light microscopy. The expression levels of StAR, P450scc and 3β-HSD were detected by RT-PCR, Western Blot and fluorescence microscopy analysis in leydig-like cells derived from the ES cells., Results: ES-D3 cells were transfected with plasmid containing SF-1 gene successfully, and SF-1 was expressed 24 h after transfection. The SF-1-transfected ES-D3 cells were induced by RA and 8Br-cAMP to differentiate into leydig-like cells. The differentiated cells showed spindle shape with tentacles, which expressed the specific protein marker for leydig cells 3β-HSD1 and P450scc. Meanwhile, in these leydig-like cells, the expression of StAR increased compared with control group. 3β-HSD1, P450scc and StAR were not detected in negative control group., Conclusion: When the ES-D3 cells are transfected with SF-1 plasmid and then treated with RA and 8Br-cAMP, the cells are able to differentiate into leydig-like cells, indicating that the model of directional differentiation of ES cells into leydig-like cells has been constructed successfully.

Soil and foliar application of melamine (ME) treatments to 'Zaoshu 5' Chinese cabbage were investigated. The ME was degraded very slowly in soil treated with different dosages (40,160 and 800 mg x kg(-1)), and 90 days later the residuals of ME were 21.1%, 15.8% and 43.6% respectively. The Chinese cabbage could take in exogenously applied ME through its root and stem leaf and accumulate it to considerable levels with the increasing applied density. In soil application test, the maximum and minimum contents of ME were 105.7 and 8.0 mg x kg(-1) in root, and 139.9 and 7.1 mg x kg(-1) in stem leaf; the ME transport occurred from root to stem leaf. In foliar application test,the maximum and minimum contents of ME were 4.3 and 0.9 mg x kg(-1) in root, and 8.5 and 3.2 mg x kg(-1) in stem leaf. In soil application test,the low level of ME (40 mg x kg(-1)) increased the biomass yield by 9.8% and the high level of ME (800 mg x kg(-1)) decreased the biomass yield by 15.9%; the contents of chlorophyll and soluble sugar increased,but the content of Vitamin C decreased. Foliar application ME had no obvious significance on the growth of Chinese cabbage. The studies indicate that the residual time of ME in soil is long and the Chinese cabbage can absorb exogenously applied ME and ME can affect the growth of Chinese cabbage.

Recent epidemiological evidence demonstrates that boys born to women exposed to phthalates during pregnancy have an increased incidence of cryptorchidism, hypospadias, testicular cancer and spermatogenic dysfunction, which are collectively referred to as testicular dysgenesis syndrome (TDS). TDS may be attributed to the dysfunction of Leydig cells and Sertoli cells during their differentiation after exposure to phthalates in utero. Fox example, Leydig cell functions are significantly affected by phthalates, leading to the decrease of two Leydig cell products--insulin-like growth factor 3 (INSL3) and testosterone, which are critical factors for testis descent. The disorientation of Leydig cells and Sertoli cells in the adult testis may be the cause of spermatogenic dysfunction.