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1.
The effect of phenylephrine, an alpha-1 adrenergic agonist, on development of body asymmetry was studied using a rat whole embryo culture system. Embryos were explanted at the presomite stage, cultured in 100% rat serum containing various concentrations of phenylephrine, and examined at the 20-25 somite stage for sidedness of asymmetric body structures, namely, bulboventricular loop, allantoic placenta, and tail. Phenylephrine treatment resulted in a dose-dependent increase of situs inversus with a maximum incidence of 52%. Coadministration of prazosin, an alpha-1 adrenergic antagonist, almost completely prevented this effect. Our results suggest that receptor-mediated stimulation of the alpha-1 adrenergic pathway is involved in the control of normal body asymmetry in developing rat embryos. 相似文献
2.
Binding sites of HeLa cell nuclear proteins on the upstream region of adenovirus type 5 E1A gene. 总被引:6,自引:3,他引:3 下载免费PDF全文
Twenty one binding sites of HeLa cell nuclear proteins were identified on the upstream region of adenovirus type 5 E1A gene using DNase I footprint assay. The proximal promoter region contained five binding sites that overlapped the cap site, TATA box, TATA-like sequence, CCAAT box, and -100 region relative to the E1A cap site(+1). The -190 region was a potential site for octamer-motif binding proteins, such as NFIII and OBP100. An upstream copy of the E1A enhancer element 1 was the site for a factor (E1A-F) with the binding specificity of XGGAYGT (X = A, C; Y = A, T). E1A-F factor also bound to three other sites, one of which coincided with the distal E1A enhancer element. The distal element also contained a potential site for ATF factor. The adenovirus minimal origin of DNA replication competed for DNA-protein complex formation on the CCAAT and TATA box region and the -190 region, suggesting that these regions interacted with a common or related factor. 相似文献
3.
The membrane viscosity of peripheral blood lymphocytes (PBLs) of equine, bovine and canine was measured by the use of time-resolved fluorescence depolarization technique with 1, 6-diphenyl-1,3,5-hexatriene (DPH). The viscosity values were 0.55, 0.59 and 0.50 poise for equine, bovine and canine PBLs, respectively. These values were compared with steady-state anisotropies and order parameters measured from electron spin resonance (ESR) of 5-doxyl stearic acid. Both values were increased with increase of viscosity. The fluid property of the membranes stimulated with phytohemagglutinin-P (PHA) was measured with steady-state fluorescence anisotropy and ESR. Little change of membrane fluidity was recognized with both methods during the stimulation with PHA. It appears that PHA activation process for these lymphocytes does not included large increase of the membrane fluidity which significantly accelerate the diffusion velocity of receptors in the plasma membrane. 相似文献
4.
The expression of c-H-ras and proliferating cell nuclear antigen (PCNA) in primary cultures of rat hepatocytes was determined in order to elucidate the relationship between the c-H-ras gene and the S phase of the cell cycle. In cells treated with EGF, elevation of c-H-ras expression was detected at the 22nd, 34th, 44th, and 54th h after plating, PCNA expression and DNA synthesis were detected at the 44th and 54th h. In cells without EGF treatment, only c-H-ras expression was detected at the 44th and 54th h. In our previous report, we showed that c-myc expression increased within several hours after plating, suggesting that isolated hepatocytes traverse from G0 to G1 under culture conditions, regardless of EGF treatment. These results clearly showed that the c-H-ras gene of adult rat hepatocytes was expressed in the mid-to-late G1 phase of the cell cycle as well as in the early S phase in primary culture. 相似文献
5.
Halothane prevents nitrous oxide teratogenicity in Sprague-Dawley rats; folinic acid does not 总被引:1,自引:0,他引:1
The teratogenic effects of nitrous oxide (N2O) administered with halothane or folinic acid (FA) were studied in two separate experiments using a total of 206 timed-pregnant Sprague-Dawley rats. In each experiment, rats were exposed to either 1) air (n = 30-40); 2) N2O (50-75% for 24 h on day 8 of pregnancy, n = 20-30); 3) test agent (i.e., 0.27% halothane for 24 h on day 8 of pregnancy; or 5 mg/kg/day of FA on day 5-13 of pregnancy, subcutaneously by osmotic pump, n = 20-30); or 4) N2O + test agent (n = 20-30). Cesarean sections were performed on day 20, and fetuses were examined for visceral and skeletal abnormalities. There were no differences in pregnancy rate, number of implantations and live fetuses per rat, and fetal weight among any of the groups. Treatment with N2O resulted in significantly higher incidences of resorptions and of major visceral and minor skeletal abnormalities. Halothane administered with N2O protected against these effects; folinic acid did not. Using an additional 65 nonpregnant rats, hepatic methionine synthase activity was measured after treatment with 50% N2O, 50% N2O plus 0.27% halothane, or 50% N2O plus 5 mg/kg/day of folinic acid. Methionine synthase activity was equally depressed in all groups. These findings do not support the commonly held theory that inactivation of methionine synthase is the sole cause of N2O teratogenicity; rather, they suggest a multifactorial etiology, which may include changes in uterine blood flow. 相似文献
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Transforming DNA sequences in rat cells transformed by DNA fragments of highly oncogenic human adenovirus type 12. 下载免费PDF全文
Rat cell lines tranformed by viral DNA fragments, EcoRI-C and HindIII-G, of adenovirus type 12 DNA were analyzed for the viral transforming DNA sequences present in cell DNAs. Cell lines transformed by the EcoRI-C fragment of adenovirus type 12 DNA (leftmost 16.5% of the viral genome) contain most of the HindIII-G sequences of the HindIII-G fragment, but at a different frequency depending on the portions of the fragment. The sequence of the AccI-H fragment of adenovirus type 12 DNA (the left part of the HindIII-G; leftmost 4.5% of the viral genome) was detected dominantly in cells transformed by the HindIII-G fragment Southern blot analysis showed that viral DNA sequences are present at multiple integration sites in high-molecular-weight cell DNA from cells transformed by the EcoRI-C or HindIII-G fragment of adenovirus type 12 DNA. These results suggest that most of the HindIII-G sequences in cells transformed by the HindIII-G fragment are present as fragmented forms. 相似文献