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Dr. Ulrich Heber 《Planta》1959,54(1):34-67
Ohne ZusammenfassungMit 15 Textabbildungen 相似文献
97.
Cut leaves of spinach were infiltrated with solutions containingoxidation-sensitive fluorescent dyes. Excess solution was removedfrom the intercellular space by centrifugation. Fluorescenceof the dyes D494 and D283 started to decrease immediately afterthe onset of fumigation with ozone at concentrations similarto or not much higher than ambient concentrations in air onsunny days. Only part of ozone entering the leaves was interceptedby the dye. The major part was degraded by unspecified reactions.Photosynthesis was not inhibited while the introduced dye wasoxidized by ozone, showing that open stomata facilitated gasexchange after the introduction of dye into the leaf interior.Feeding of ascorbate to the leaves via the petiole failed toaffect the ozone-dependent decrease in fluorescence emissionfrom the dye. Likewise, infiltration of leaves by solutionscontaining dye and 10 mM ascorbate did not produce significantprotection of the dye against oxidation by ozone. However, suchprotection was observed in vitro, when solutions of dye andascorbate were bubbled with air containing ozone. Although thereis little doubt that apoplastic ascorbate occupies a centralposition in the antioxi-dative defense of leaf tissue, we aresurprised to find that it is much less effective than expectedto decrease the oxidation of fluorescent lipophilic probes whichhad been introduced into the leaf interior. The data suggestthat ascorbate is not a primary reductant of ozone in the apoplast.With a microscope-mounted CCD-camera connected to the gas exchangeequipment we obtained spatial information on the fluorescencesignal and present first results on an heterogeneous distributionof ozone action. (Received June 20, 1997; Accepted December 26, 1997) 相似文献
98.
Ángel Canales Gutiérrez Germán Belizario Quispe Alfredo Pelayo Calatayud Mendoza Heber Nehemías Chui Betancur Edilberto Huaquisto Ramos 《Revista espa?ola de geriatría y gerontología》2021,56(1):24-28
The objective is to evaluate thermal comfort in the rural highlands of Peru and determine if thermal conditions influence the risk of respiratory infections. The probit regression model is used for this, with the unit of analysis being adults over 60 years of age. The information source is the data from the National Household Survey and the National Service of Meteorology and Hydrology of Peru. In addition, it was possible to monitor the temperature and the interior relative humidity of 4 types of bedrooms with a thermo-hygrometer and compared it with the desired thermal comfort index criterion. The results show that if the air temperature drops on average by one degree (1° C) in the area of residence, the probability of risk of respiratory infections in older adults increases by 0.18, although the relative humidity and the wind speed were not statistically significant at 1% significance level. Finally, the 4 types of bedrooms evaluated lacked the desired thermal comfort and increased the risk of acquiring respiratory infections. 相似文献
99.
U Heber 《Biochimica et biophysica acta》1969,180(2):302-319
100.
We have previously described the binding of biologically active 125I gonadotropin-releasing hormone to the 10,800 × g membrane fraction prepared from 7-day castrate adult female rat anterior pituitary glands. Specific binding with two equilibrium association constants (109 liters per mole and 105 liters per mole) was found and an equilibrium competitive binding radio-receptor assay established. In order to further characterize the gonadotropin-releasing hormone receptor, 20 synthetic analogs with known bioactivity were tested in the radioreceptor assay. In vivo biological activity correlated with high affinity receptor binding but not with low affinity binding. Inhibitory analogs with no in vivo biological activity and weak antagonistic properties did not bind, while in vivo active or superactive analogs bound to high affinity receptors. These findings suggest that the high affinity gonadotropin-releasing hormone receptor binds only biologically active gonadotropin-releasing hormone like peptides and that this binding may be the initial step in gonadotropin-releasing hormone actions at the pituitary level. 相似文献