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151.
Effects of viral transformation on synthesis and secretion of collagen and fibronectin-like molecules by embryonic chick chondrocytes in culture 总被引:4,自引:0,他引:4
Monolayer cultures of chondrocytes isolated from 11-day-old chick embryo vertebral cartilage were transformed by Rous sarcoma virus, and the effects of transformation on synthesis and secretion of extracellular proteins by these cells were studied. Transformation resulted in decreased synthesis of type II collagen which did not appear to be due to underhydroxylation of collagenous protein but to a decrease in the total amount synthesized. Carboxymethyl-cellulose chromatography and polyacrylamide disc gel electrophoresis failed to demonstrate any alpha 2 chains as a result of the transformation, suggesting that conversion of type II to type I collagen did not occur. In contrast to the decrease in collagen synthesis, synthesis of a molecule with biochemical characteristics similar to fibronectin increased markedly in virally transformed cultures. Although there were no significant differences in the amount of fibronectin-like molecules in the cell layers of normal and transformed chondrocytes, a marked increase of these molecules in the culture media of the transformed cells was demonstrated. These findings were confirmed by experiments with temperature-sensitive mutants of the virus. 相似文献
152.
L I Kulikova G A Iatskiavichiute V S Tsvetkov Iu E Ershikova S P Gordienko 《Biulleten' eksperimental'no? biologii i meditsiny》1987,104(8):224-226
Antibodies to calcitonin, parathyroid hormone and cortisol are detected in acute stage of infection-caused bronchial asthma. The appearance of antibodies is paralleled by marked hypercalcaemia. The antibodies may bind excessive hormones in the blood, preventing further hormonal imbalance. Ten-day treatment with glucocorticoids decreased the amount of antibodies possibly due to normalization of hormonal secretion and restoration of their balance. As a result, calcium blood levels returned to normal. 相似文献
153.
State of aggregation of the (Ca2+ + Mg2+)-ATPase studied using saturation-transfer electron spin resonance 总被引:1,自引:0,他引:1
The state of aggregation of the (Ca2+ + Mg2+)-ATPase in the membrane of sarcoplasmic reticulum and in reconstituted membrane systems has been studied using saturation-transfer electron spin resonance (ST-ESR). Saturation-transfer ESR spectra show that in the sarcoplasmic reticulum, the ATPase is relatively free to rotate, with an effective rotational correlation time of approx. 33 microseconds at 4 degrees C, consistent with a monomeric or dimeric structure. The rate of rotation is observed to decrease with decreasing molar ratio of lipid to protein. In reconstituted systems, rotational motion of the ATPase on the millisecond time scale ceases when the lipids are in the gel phase. Addition of decavanadate, which causes the formation of crystalline arrays in negatively stained electron micrographs, results in only a small reduction in rotation rate for the ATPase in the membrane. The experiments are interpreted in terms of a short-lived (on the millisecond time scale) protein-protein interaction, with the formation of crystalline clusters of ATPase molecules which form and melt rapidly. 相似文献
154.
Gatewood and the first thenar pedicle 总被引:1,自引:0,他引:1
155.
J G Fukushima O Cascone J A Santomé M J Biscoglio de Jimenez Bonino 《International journal of peptide and protein research》1987,30(3):365-370
Reactivity of histidine residues in equine growth hormone to ethoxyformic anhydride was studied. The existence of two kinetically different sets was demonstrated: one of them including only the slow reacting histidine 169 (k = 0.164 min-1) and the other containing fast reacting histidines 19 and 21 (k = 0.892 min-1). A correlation between the decrease in the capacity to compete with 125I-labeled hormone for rat liver binding sites and the degree of ethoxyformylation of the fast group was found. Circular dichroism studies indicated no significant conformational changes in the protein with all three residues modified. These results fully agree with those obtained for bovine growth hormone which is further evidence supporting the vinculation of histidines 19 and/or 21 with the binding site of these hormones to their specific receptors. 相似文献
156.
Mycotoxin production by various toxigenic fungi, growing on a bread analogue, was investigated at various water activities (aw ) and pH combinations. Citrinin, ochratoxin A and sterigmatocystin could be detected at aw > 0·80, while patulin was only observed at aw = 0·95. These results show that some toxins may be produced at lower water activities than have been reported on synthetic media and suggest that, where possible, natural substrates should be used to investigate factors affect-ing mycotoxin production in foodstuffs. 相似文献
157.
158.
The selective action of the antibiotics chloramphenicol and cycloheximide on the synthesis of ferredoxin in liquid cultures of Chlamydomonas reinhardii was studied. Highly specific antibodies raised against Chlamydomonas ferredoxin were used to determine the in vivo synthesis of apoferredoxin and conversion into native protein. The results indicate that 80S ribosomes are involved in the synthesis. Chlamydomonas cells growing in the absence of iron did not synthesize immunologically detectable amounts of ferredoxin. We suggest that this is based upon feed-back inhibition of apoferredoxin synthesis at the translational level.Abbreviations CAP
chloramphenicol
- CHI
cycloheximide
- IgG
Immunoglobulin G
- PBS
140.4 mM NaCl. 9 mM Na2HPO4, 1.3 mM NaH2PO4 (pH 74)
- SDS
sodium dodecvl sulphate
- Fd
Ferredoxin
- apoFd
Apoferredoxin
- CM-Fd
Scarboxymethylated Fd
- TCA-Fd
Fd treated with trichloroacetic acid 相似文献
159.
160.
An apparatus for polyacrylamide slab gel electrophoresis is decribed which combines all parts into one integral unit. It eliminates several steps in the process of sealing, pouring, and setting the gels. Construction is easy with modest workshop facilities and the design easily adapted to suit most requirements. The apparatus provides a high degree of versatility and is suitable for use with many slab gel electrophoretic techniques. 相似文献