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31.
The kidneys of androgen stimulated mice exhibit a hypertrophic response but no hyperplasia or concomitant DNA replication. Androgens increase the expression of several genes in mouse kidney. The response of the beta-glucuronidase gene to testosterone in this tissue is characterized by a 1-2 day lag and relatively slow induction kinetics. The gene coding for kidney androgen-regulated protein (KAP) exhibits quite a different response to the hormone when compared on the basis of initial response to a given dose, dose required to produce maximal response, and apparent sensitivity to low levels of androgen-receptor complexes in renal nuclei. The analysis of the accumulation of the mRNAs produced by these two genes suggests that gene-specific differential sensitivity to androgen receptor complexes governs the development of the cellular male phenotype in this tissue. 相似文献
32.
J D Watson M Eszes R Overell P Conlon M Widmer S Gillis 《Journal of immunology (Baltimore, Md. : 1950)》1987,139(1):123-129
The cloned murine interleukin 3 (IL 3)-dependent cell lines FD.C/1, 32Dc1-23, and KP3 can each be switched to interleukin 2 (IL 2)-dependent growth states. Replication-defective retroviral vectors have been used to introduce the v-src oncogene into each of these cell lines maintained in either an IL 3- or an IL 2-dependent growth state. These cell lines maintained in an IL 3-dependent growth state were converted to lymphokine-independent growth after infection with v-src. These same cells maintained in an IL 2-dependent growth state and infected with v-src maintained strict lymphokine dependence for growth. Another cloned murine IL 3-dependent cell line, GM, can be switched to a granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent growth state. GM cells maintained as IL 3- or GM-CSF-dependent cells readily converted to a lymphokine-independent growth state when infected with v-src. These experiments indicate that either there exist differences in the biochemical mechanisms of signal transduction through the IL 3- and IL 2-specific receptors, or developmental processes associated with the switching of cells to an IL 2-dependent growth state influence expression of the v-src gene product. These cell lines offer new ways not only for analyzing biochemical pathways that regulate cell growth, but also for analyzing the control of oncogene expression. 相似文献
33.
N J Gooderham D Watson J C Rice S Murray G W Taylor D S Davies 《Biochemical and biophysical research communications》1987,148(3):1377-1382
2-Amino-3,8-dimethylimidazo(4,5-f)quinoxaline (MeIQx) is a potent mutagen found in cooked food. MeIQx and its isotopically labelled (13C, 15N2 and 14C) analogues were synthesised and used for metabolic studies in vivo. An equimolar mixture of MeIQx and its 13C, 15N2 stable isotope labelled analogue (containing tracer amounts of 14C-MeIQx) was given intraperitoneally to mice. Some 67% of the radioactivity was eliminated in urine and faeces within 24h. Four radiolabelled species were observed when urine was analysed by HPLC, corresponding to unchanged MeIQx and three more polar metabolites. Urine was analysed directly by HPLC-thermospray mass spectrometry. Four signals were observed containing the characteristic 1:1 isotopic doublet, corresponding to unchanged MeIQx, an MeIQx glucuronide, and two uncharacterized metabolites. 相似文献
34.
A trophic effect of epidermal growth factor (EGF) on rat colonic mucosa in organ culture 总被引:1,自引:0,他引:1
The development of an organ-culture system for rat colonic mucosa has enabled a direct assessment of the effect of epidermal growth factor (EGF) on cell division. An augmented mitotic index (AIm) has been employed to identify changes in cell proliferation. Explants of colonic mucosa from four animals were maintained in a medium containing serum for five days. On the fifth day of culture, half of the explants received fresh medium containing EGF (40 ng/ml) and the remainder (controls) fresh medium only. At 6, 12, 24 and 48 hr thereafter groups of both experimental and control explants received the metaphase-arresting drug vincristine (4 micrograms/ml) for 3 hr prior to fixation. The proportions of vincristine-arrested metaphases within the explants were determined. Analysis of the data indicates that when serum is present exogenous EGF exerts a trophic effect which increases with time (P less than 0.001). In a second experiment colonic explants from four animals were maintained for five days in a serum-free medium and were then divided into groups, each of which received one of a range of concentrations of EGF. The AIm was determined for each group after 36 hr. It was found that increasing concentrations of EGF produce a small but significant increase in cell proliferation (P less than 0.01). This effect, however, was less pronounced than that seen when serum was present. These results suggest that EGF has a trophic action on the colon and interacts with additional factors found in serum. 相似文献
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Lidija Simova Carolyn Williams Georgi D. Efremov Aleksandra Gordova-Muratovska Stojka Suštić Eila K. Watson Robert Williamson 《Human genetics》1990,85(4):432-433
Summary Chromosomes from 19 unrelated Southern Yugoslav families in which cystic fibrosis (CF) occurs were analysed for the presence
of the ΔF508 mutation, using polymerase chain reaction amplification followed by dot blot and polyacrylamide gel analysis.
Of the 38 CF chromosomes, 15 (39.5%) carry the ΔF508 deletion. Restriction fragment length polymorphism haplotypes for KM19/PstI, XV2c/TaqI and J3.11/PstI marker loci were determined and are compared for a total of 34 N and 37 CF chromosomes. 相似文献
38.
Expression of adenovirus type 2 DNA polymerase in insect cells infected with a recombinant baculovirus. 总被引:5,自引:0,他引:5 下载免费PDF全文
Sequences encoding adenovirus type 2 DNA polymerase were placed under control of the polyhedrin promoter and inserted into the baculovirus Autographa californica nuclear polyhedrosis virus by homologous recombination. Insect cells infected with the recombinant virus produced substantial amounts of the adenovirus type 2 DNA polymerase protein which was functional in both DNA polymerase and replication initiation reactions. Thus, the baculovirus expression system can provide active adenovirus type 2 DNA polymerase that is produced in quantities suitable for biochemical and structural analysis. 相似文献
39.
40.
Lowering of the extracellular Na+ concentration enhances high-K+-induced formation of inositol phosphates in the guinea-pig ileum. 总被引:7,自引:0,他引:7 下载免费PDF全文
1. Formation of inositol phosphates (InsPs) was measured in cross-chopped slices or dispersed cells, isolated by collagenase treatment, of guinea-pig ileum longitudinal smooth muscle pre-labelled with [3H]inositol. 2. Elevation of the extracellular K+ concentration by equimolar replacement of Na+ induced accumulation of InsPs in the dispersed cells and in the tissue slices. These effects were blocked by neither tetrodotoxin (1 microM) nor atropine (10 microM), and were approximately additive with carbachol-induced accumulation. 3. In the tissue slices, the response to K+ was partially inhibited by nifedipine (10 microM) and by CdCl2 (0.3 mM), but the carbachol-induced response was not altered. 4. Accumulation of InsPs induced by KCl-excess solution (high-K+ solution without Na+ replacement) was suppressed strongly by nifedipine and completely by CdCl2. The response to KCl excess was approx. 40% of that to high K+ with Na+ replacement. 5. Low-NaCl solution (replacement of NaCl with equimolar sucrose) also produced InsPs, and this was not blocked by either nifedipine (10 microM) or CdCl2 (0.3 mM). 6. The formation of InsPs by a maximally effective concentration of carbachol (1 mM) in the presence of KCl excess or low NaCl was greater than the additive effect of the two stimuli on their own. Enhancement of the carbachol-induced response by KCl excess disappeared in the presence of CdCl2 (0.3 mM). 7. These data suggest that formation of InsPs induced by high-K+ solution with equimolar replacement of Na+ consists of two components, i.e. high-K+-induced inositol-phospholipid hydrolysis by Ca2+ entry through voltage-sensitive channels, and low-Na+-induced formation of InsPs, insensitive to Ca2+ antagonists, but that both of them do not contribute significantly to the activation of phospholipase C by muscarinic stimuli. 相似文献