Long-range periodic sequence of the cement/silk protein of Stenopsyche marmorata: purification and biochemical characterisation.

The long-range periodic amino acid sequence of the bifunctional silk/cement protein from larvae of the caddisfly, Stenopsyche marmorata, is discussed in this study. The protein, named the S. marmorata silk protein (Smsp-1), was first purified to electrophoretic homogeneity. The results of Edman-based sequencing of Smsp-1 tryptic digests were consistent with the amino acid sequence deduced from a cDNA clone of the Smsp-1 gene. All undetected amino acids in the Edman-based sequencing were encoded as Ser, suggesting the presence of O-phospho-Ser. (31)P-NMR and an O-phospho-amino acid analysis successfully showed that the O-phospho-Ser residue occurred in a clustered manner, serving a cement function for Smsp-1. Two patterns of non-phosphorylated repeats, -SLGPYGDPRGDXLGPYGG- (X = V, G or D) and -GVGPYGDGLGPYGG-, were enriched in Smsp-1 compared with the O-phospho-Ser cluster, and have fibre-forming functions.

Short-term effects of di-(2-ethylhexyl) phthalate on testes, liver, kidneys and pancreas in mice.

AIM: To determine the biochemical effect of di-(2-ethylhexyl) phthalate (DEHP) on testes, liver, kidneys and pancreas on day 10 in the process of degeneration of the seminiferous epithelium. METHODS: Diets containing 2% DEHP were given to male Crlj:CD1(ICR) mice for 10 days. The dose of DEHP was 0.90 +/- 0.52 mg/mouse/day. Their testes, livers, kidneys and pancreata were examined for detection of mono-(2-ethylhexyl) phthalate (MEHP), nitrogen oxides (NOx) produced by peroxidation of nitric oxide (NO) with free radicals, and lipid peroxidation induced by the chain reaction of free radicals. RESULTS: Histological observation and serum analysis showed the presence of severe spermatogenic disturbance, Leydig cell dysfunction, liver dysfunction and dehydration. Unexpectedly, the concentration of MEHP in the testes was extremely low compared with that in the liver. However, the concentration of the NOx in the testes was as high as the hepatic concentration. Furthermore, free radical-induced lipid peroxidation was histochemically detected in the testes but not in the liver. CONCLUSION: The results indicate that DEHP-induced aspermatogenesis is caused by the high sensitivity of the testicular tissues to MEHP rather than the specific accumulation or uptake of circulating MEHP into the testes.

Effects of maternal exposure to diethylstilbestrol on the development of the reproductive system and thyroid function in male and female rat offspring.

Diethylstilbestrol (DES) was administered subcutaneously at 1.5 or 15 microg/kg/day (DES 1.5 group, DES 15 group) to pregnant SD rats daily on days 7-21 of gestation to investigate its effects on the development and functions of the reproductive system and thyroid gland in their offspring. Of the 11 pregnant rats in the DES 15 group, only one delivered a live pup. Rat pups in the DES 1.5 group were autopsied at 1, 3, or 6 weeks after birth. In the DES 1.5 group, the plasma T4 concentrations at all weeks of age at autopsy were significantly increased, the TSH concentration at 6 weeks of age was also significantly increased, and the height of thyroid follicular epithelial cells was increased at 3 weeks. The testosterone concentration in the DES 1.5 group at 6 weeks was significantly decreased and the plasma LH concentration was increased. The DES treatment increased the plasma FSH concentration in female pups at 3 weeks, increased the percentages of primary and secondary ovarian follicles, and decreased the percentage of primordial follicles, but did not influence the timing of the vaginal opening or the onset of the estrous cycle. These observations indicate that prenatally administered DES increases thyroid function, and has an inhibitory effect on testicular function and a promoting effect on female reproductive function.