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931.
The localization of the elongation factor Tu (EF-Tu) in ultrathin cryosections of E. coli cells was determined with the electron microscope using a highly specific immunological labelling technique. EF-Tu is distributed almost homogeneously throughout the cytoplasm. Although it has often been suggested that EF-Tu could be part of a putative prokaryotic cytoskeleton, we did not find any evidence for supramolecular assemblies, such as fibres or filaments, containing a large amount of EF-Tu. EF-Tu was not observed in association with the outer cell membrane and periplasmic space. A topological relationship with the inner membrane is not apparent in our micrographs. In cells in which the EF-Tu level is raised significantly, the protein piles up in discrete cell regions.  相似文献   
932.
933.
Specific antibodies and protein proteinase inhibitors will inhibit cell-surface proteinase activity on human fibroblasts and cause a concomitant inhibition of DNA synthesis and of cell multiplication. An insolubilized proteinase inhibitor also inhibits cell multiplication. The same reagents partially inhibit the multiplication of mouse L cells, both in monolayer and suspension culture, and inhibit the mitogenic effect of epidermal growth factor (EGF) on both types of cell.  相似文献   
934.
The effect of transcranial magnetic stimulation (TMS) of the right and the left frontotemporal areas on the short- and long-term verbal memory was studied in healthy subjects and patients with Parkinson’s disease. TMS with a magnetic induction of more than 1.2 T at 10 Hz was found to affect the short-term memory when applied to the left frontotemporal area and to have no significant effect on this type of memory when applied to the right frontotemporal area. In healthy subjects, TMS applied to the left or the right hemisphere did not affect the long-term memory. However, in patients with Parkinson’s disease, significant changes in the long-term memory were observed upon TMS of either the left or the right hemisphere. The effect was more evident on TMS of the right hemisphere.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 4, 2005, pp. 33–36.Original Russian Text Copyright © 2005 by Gimranov, Mal’tseva.  相似文献   
935.
Four of six human monoclonal IgM proteins were found to react best with Klebsiella polysaccharides containing 3,4py beta DGal (pyruvic acetalated D-galactopyranose), one with Klebsiella polysaccharides with 4,6pyDGlc; the sixth is uncharacterized. The combining sites of two of these (IgMWEA and IgMNAE) were essentially indistinguishable by quantitative precipitin studies at varying pH and by quantitative precipitin inhibition assays, but the other two differed in specificity of their combining sites from these and from each other. These differences were detected by precipitin inhibition assays with 3,4py beta DGal-containing oligosaccharide alditols, the R and S isomers of methyl 4,6py alpha DGal, the R isomer of methyl 4,6py beta DGal, or the R and S isomers of methyl 4,6py alpha DGlc, and -beta DGlc. In all of these except the S isomer of methyl 4,6pyDGal and R isomer of methyl 4,6pyDGlc, the carboxyl group is axial to the plane of the acetal ring. Their specificity appears to be determined by the nonreducing ends of chains and is considered to be cavity-type.  相似文献   
936.
The amount of radioactivity which derived from 14C-labeled pollutants was determined in liver, kidney, intestine, blood, muscle and gills of carp, exposed for 6, 24 and 72 hr to high external concentrations of urea, methanol, atrazine and PCP. The results allowed one to calculate roughly the uptake rate for these compounds. It was low for urea (0.055 micrograms/g per hr), higher for methanol (0.12) and atrazine (0.16) and highest for PCP (1.5). The bioaccumulation factors (BFs) were determined for the different substances and organs. They correlated with the hydrophilic-lipophilic nature of the chemicals. The more lipophilic the substances the more accumulation occurred in the liver. PCP accumulated the most. BF was 300-400 in most tissues except muscle where it was quite low. The BF was 3-4 for atrazine in liver, kidney and intestine, but just 1 in blood, muscle and gills. There is some evidence that the BF for methanol equals 1 in liver, kidney, gills and intestine. It is less than 1 in blood and muscle. Urea was equally distributed in all organs and in the external medium.  相似文献   
937.
Ca2+-phospholipid dependent protein kinase activity and the effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) on H+ secretion was studied in guinea-pig parietal cells. In resting parietal cells PK-C activity was distributed almost equally in both the cytosolic and particulate cell fraction. Exposure of the cells to TPA resulted in a loss of cytosolic PK-C activity which was not accompanied by a concomitant increase of particulate activity. Furthermore TPA inhibits the K+/H+-ATPase and dissipates H+ gradient in intact gastric vesicles by a protonophoric action. The role of these biochemical events for the antisecretory action of TPA found in the intact parietal cell are discussed.  相似文献   
938.
Crude extracts of Streptomyces griseus grown on soybean flour-enriched medium contain high levels of cytochrome P-450. The cytochrome P-450-enriched fractions, obtained by ammonium sulfate fractionation (30-50% saturation), catalyze the NADPH-dependent oxidation of a variety of xenobiotics when complemented with both spinach ferredoxin:NADP+ oxidoreductase and spinach ferredoxin. Reactions observed are aromatic, benzylic and alicyclic hydroxylations, O-dealkylation, non-aromatic double bond epoxidation, N-oxidation and N-acetylation.  相似文献   
939.
In this paper, we describe an efficient procedure for the purification of yeast phosphofructokinase. This procedure eliminates any time delay and enables to obtain an enzyme with minimum proteolytic alterations. The molecular weights of the oligomeric enzyme and of its constitutive subunits were both evaluated by means of several independent methods. However, the accuracy of each measurement was not sufficient to discriminate between an hexameric and an octameric structure of the enzyme oligomer. On the other hand, crosslinking experiments demonstrated the octameric structure of yeast phosphofructokinase. Obviously, some methods of molecular weight determination have led to erroneous results. In particular, our experiments show that the reliability of molecular weight determinations performed by gel filtration of native proteins must be considered with caution.  相似文献   
940.
Origin of the epidermis in root meristems   总被引:3,自引:0,他引:3  
  相似文献   
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