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41.
The electrical potential distribution has been measured preciselyaround the root surface of the bean sprout Vigna mungo (L) Hepper.A large negative potential well was found at the growth portionof the root tip. Also, in the matured region of the root, wefound a negative potential well at an unspecified position inspite of the fact that nothing was detected on the smooth surface.A lateral root emerge was found to have initiated after 15–20hours just at the position corresponding to the potential well.With the expectation that these potentials can be elucidatedbased on the transport of ions which are released or absorbedby the root as a result of cell activity, we precisely measuredthe concentrations of major ion species (K+, H+, and Cl)around the root. The theoretical potential distribution curvesobtained by putting all the concentration data into the Henderson'sEquation for a liquid junction (diffusion) potential coincidedwell with the experimental curves. (Received October 24, 1994; Accepted March 24, 1995)  相似文献   
42.
By employing a bovine UDP-N-acetylgalactosamine: polypeptideN-acetylgalactosaminyl transferase (O-GalNAc transferase) cDNA as a probe, we isolated four overlapping cDNAs from a porcine lung cDNA library. Both the nucleotide sequence of the porcine cDNA and the predicted primary structure of the protein (559 amino acids) proved to be very similar to those of the bovine enzyme (95% and 99% identity, respectively). Transient expression of the clone in COS-7 cells, followed by enzymatic activity assays, demonstrated that this cDNA sequence encodes a porcine O-GalNAc transferase. The intracellular O-GalNAc transferase activity was increased approximately 100-fold by transfecting cells with the porcine cDNA.Abbreviations O-GalNAc transferase UDP-N-acetylgalactosamine: polypeptideN-acetylgalactosaminyltransferase - PCR polymerase chain reaction - SDS sodium dodecyl sulfate - PAGE polyacrylamide gel electrophoresis - GnT-III UDP-N-acetylglucosamine: -mannoside -1,4N-acetylglucosaminyltransferase III  相似文献   
43.
The inhibition of lipid peroxidation and radical scavenging effects were studied to evaluate the antioxidant activity for extracts of 17 species of seaweed. The antioxidant effect was evaluated by determination of lipoxygenase activity and by α, α-diphenyl-β-picrylhydrazyl (DPPH) decolorization. Lipoxygenase activity was depressed in the presence of aqueous and ethanol extracts of 4 algal species; Sargassum species had the highest antioxidant activity of all the species examined. The ethanol extracts of one Sargassum species showed competitive inhibition with the substrate. The same species also showed radical scavenging activity in the DPPH decolorization test. Comparison of these results shows no relationship between enzyme inhibition and radical scavenging activity. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
44.
Abstract: A newly established, sensitive, two-site enzyme-immunoassay system for brain-derived neurotrophic factor (BDNF) is described. Using this system, we investigated the tissue distribution of BDNF and developmental changes in tissue levels of BDNF in rats. The minimal limit of detection of the assay was 3 pg/0.2 ml of assay mixture. BDNF was successfully solubilized from tissues in the presence of guanidine hydrochloride but not in any of the other buffers examined. In the rat brain at 1 month of age, the highest level of BDNF was detected in the hippocampus (5.41 ng/g of wet weight), followed by the hypothalamus (4.23 ng/g) and the septum (1.68 ng/g). In other regions, levels of BDNF ranged between 0.9 and 1.7 ng/g. The level of BDNF in the posterior lobes of the cerebellum from rats at 30 days of age was slightly higher than that in the anterior lobes. The concentration of BDNF increased in all regions of the brain with postnatal development. In peripheral tissues, BDNF was found at very low concentrations (0.65 ng/g in the spleen, 0.21 ng/g in the thymus, and 0.06 ng/g in the liver). The subfractionation of the hippocampal homogenate indicated that ∼50% of BDNF was contained in the crude nuclear fraction. Immunoblots of BDNF-immunoreactive proteins extracted from the hippocampus, hypothalamus, and cerebellum contained doublet bands of protein of ∼14 kDa, a value close to the molecular mass of recombinant human BDNF. Immunocytochemical investigations showed that, in the hippocampus, BDNF was localized in the nucleus of the granule cells in the dentate gyrus and of the cells in the pyramidal cell layer. The frequency of cells that were stained in the dentate gyrus was greater than that of cells in the pyramidal cell layer.  相似文献   
45.
Cotyledons excised from dark-grown seedlings of cucumber (Cucumis sativus L.) were cultured in vitro under UV radiation at different wavelengths, obtained by passage of light through cut-off filters with different transmittance properties. Growth and the synthesis of chlorophyll (Chl) in cotyledons were inhibited and malondialdehyde was accumulated upon irradiation at wavelengths below 320 nm. Exogenous application of scavengers of free radicals reversed the growth inhibition induced by UV-B. Measurement of the fluorescence of Chl a suggested that electron transfer in photosystems was affected by UV-B irradiation. On the basis of these results, the involvement is postulated of active species of oxygen in damages to thylakoid membranes and the growth inhibition that are induced by UV-B irradiation.Abbreviations Chl chlorophyll - Fm maximal fluorescence (dark) - Fm maximal fluorescence (light) - Fv variable fluorescence (dark) - Fv variable fluorescence (light) - MDA malondialdehyde - O2 Superoxide radical - PS photosystem - qN non-photochemical quenching of fluorescence - qP photochemical quenching of fluorescence - UV-BBE biologically effective UV-B radiation - WL(T = 0.5) wavelength at which 50% transmittance occurs  相似文献   
46.
Uptake of glucose-6-phosphate by microsomes of hepatocyte in rats, human controls and patients with glycogen storage disease type Ia and Ib was studied. In rat the uptake of glucose-6-phosphate increased rapidly and reached to a plateau, but mannose-6-phosphate was not accumulated. These findings indicate that a glucose-6-phosphate specific transport system exists in the microsomal membrane. In human controls and patients with glycogen storage disease type Ia the uptake of glucose-6-phosphate was clearly observed. On the other hand, no accumulation of it was detected in a patient with glycogen storage disease type Ib. These data provide a direct evidence of the defect in the glucose-6-phosphate transport system of hepatic microsomal membrane in glycogen storage disease type Ib.  相似文献   
47.
48.
The effects of nineteen AHPA* derivatives were examined on morphine analgesia by tail-flick test in rats and on enkephalinase inhibition which was based on the formation of tyrosyl-glycyl-glycine from met-enkephalin. The correlation between the enhancement of morphine analgesia in vivo and enkephalinase inhibition in vitro was analyzed. The different analogs varied considerably in the degree of enhancement of morphine analgesia and inhibition of enkephalinase. A close relationship between enkephalinase inhibition expressed by IC50 in vitro and enhancement of morphine analgesia in vivo was observed in thirteen out of nineteen AHPA derivatives examined. One of other six AHPA derivatives which showed weak effectiveness in potentiating on morphine analgesia but was highly potent as an enkephalinase inhibitor, caused potent analgesic action when it was applied intracisternally indicating poor penetration of the blood brain barrier. The possibility was discussed that some of other compounds excluded from the linear relationship might act on other enkephalin degrading enzymes such as aminopeptidase.  相似文献   
49.
The influences of two water soluble contrast media, meglumine iothalamate and meglumine iocarmate, on the neuronal excitability and on the neuronal sensitivity to putative transmitters were examined in comparison with those of sucrose using two identifiable giant neurones of Achatina fulica Férussac (the TAN and the PON). A relatively low increase of osmotic pressure of the extracellular fluid, produced by the application of contrast media, reversed the Cl- dependent inhibition caused by a putative transmitter. The same increase of this osmotic pressure, however, did not influence the Cl- independent inhibition and the excitation of the neurone examined. The hyperpolarization of neuromembrane was caused by an increase of osmotic pressure of the extracellular fluid. Its relatively high increase was necessary to make spontaneous spike discharges disappear totally. All effects of the two contrast media, observed in this study, were due to the increase of osmotic pressure of the extracellular fluid ; no specific effect of the contrast media containing the iodine on the indicators used was observed.  相似文献   
50.
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