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871.
In the frog intestine, both in vitro and in vivo, experiments were carried out in order to increase knowledge of the mechanism of sugar exit across the basolateral membrane of the enterocyte. The frog intestine was chosen because it lacks crypt cells and, consequently, any external fluid circuit mechanism during sugar transport can be avoided. Therefore, the sugar concentration in the absorbate collected on the serosal side is likely to be similar to that present underneath the basolateral membrane of the enterocyte. Under this condition, cell and absorbate sugar concentrations are similar; yet there is a concomitant net transintestinal sugar transport. Moreover, in in vivo experiments a net transintestinal sugar transport takes place even against a concentration difference. These results suggest that sugar exit across the basolateral membrane is not simply due to a chemically facilitated diffusion. 相似文献
872.
A A Sumarokov L A Nefedova I Iu Iaroshevskaia L V Salmin N A Ozeretskovski? 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1977,(5):109-114
Prophylactic activity and side action of antiinfluenza lactoglobulin were studied under conditions of controlled epidemiological trial in 6361 persons during the epidemiological rise of influenza incidence. The data obtained pointed to the absence of any protective effect of antiinfluenza lactoglobulin. Marked allergenic properties of lactoglobulin and development of sensitization in the persons under observation were found during the study of the side-effect of the preparation. Thus, the absence of prophylactic efficacy and the sensitizing action of antiinfluenza lactoglobulin pointed to the inexpediency of its use for prophylactic and therapeutic purpose. 相似文献
873.
874.
875.
O. G. Petersen 《Plant biology (Stuttgart, Germany)》1899,17(11):168-171
876.
The published and authors' data have been summarized on (1) the spectrum and properties of crystallins in different amphibian species, (2) localization and synthesis of crystallins in different cellular compartments of the adult amphibian lens, (3) dynamics of crystallin formation during embryogenesis and (4) lens regeneration from tissues of the larval and adult amphibian eyes. The necessity of more detailed studies of crystallin synthesis during embryogenesis and lens regeneration using molecular biological and biochemical methods is stressed. The significance of this approach is illustrated by the pioneering data of Soviet scientists on crystallin polypeptides and corresponding mRNAs in development of Rana temporaria obtained with the use of DNA-RNA hybridization and immunoelectroblotting. 相似文献
877.
Using a highly effective chelator of Ca2+ and 45Ca, the concentration of Cai2+ in human and rat erythrocytes was measured both at normal and accelerated Ca2+ influx into the cells. No effect of the calmodulin-dependent reaction inhibitor R24571 was observed. The Ca-ATPase from saponin-treated erythrocytes was characterized by a high affinity for Ca2+ (K 0.5-0.7 microM). This value is 2-3 times as low as that for Ca2+ concentration causing a 50% increase of the Ca-ATPase activity in erythrocyte ghosts obtained during hypoosmotic hemolysis. The Ca-ATPase activity in saponin-treated erythrocytes did not change either under the effect of calmodulin or by R24571. It was assumed that calmodulin did not participate in the regulation of the Ca2+-pump operation in erythrocytes in vivo. 相似文献
878.
The dependence of adrenal gland adenylate cyclase desensitization on the dose of in vivo injected ACTH, the time of occurrence and duration of the enzyme refractory period and the dependence of desensitization on the number of ACTH injections were analyzed. The experiments were carried out on guinea pigs injected with prolonged action preparations of ACTH (4 and 6 units) daily for 1-6 days. Intramuscular injections of ACTH caused adenylate cyclase refraction to the repeated action of the hormone. The effect of desensitization was the most conspicuous within the first few hours after hormone injection. The decrease of adenylate cyclase sensitivity and the duration of this effect were found to depend on the ACTH dose as well as on the number of injections. It has been shown for the first time that a single in vivo injection of 0.9% NaCl causes short-term desensitization of adenylate cyclase to the repeated action of much higher doses of ACTH in vitro, presumably due to endogenous ACTH release in response to weak stress exposure. The periodicity of changes in adenylate cyclase sensitivity upon prolonged hormone administration is discussed. Sensitization of the enzyme upon daily short-term exposure to physiological doses of ACTH (administration of 0.9% NaCl for 6 days) was revealed. 相似文献
879.
V I Krupianko 《Biokhimii?a (Moscow, Russia)》1988,53(12):2059-2061
It is known that the affinity of all nucleoside monophosphate isomers for RNAase active sites increases in the following order: 5'-NMP----3'-NMP----2'-NMP, irrespective of the RNAase type (pyrimidine-specific, guanine-specific or non-specific) and stage of activity (transferase, hydrolase). It is known also that the nucleotides with the same degree of isomerism have substantially the same conformation. It was thus supposed that the structure of active sites of RNAase has common features with a closer similarity in case of pyrimidine-specific (EC 3.1.4.22), guanine-specific (EC 3.1.4.8) and non-specific (EC 3.1.4.23) RNAases. 相似文献
880.
Extracellular electrophysiological recording from olfactory receptors in the antennae of tobacco hornworm larvae (Manduca sexta (Johan.)) has revealed that cells respond differentially to different odors by changing latency, rate of increase of frequency of firing, rate of adaptation, and alternation of frequency increase and decrease. The resulting temporal patterns of spike activity could function as a code to allow for discrimination among various plant odors.
This research was supported by National Science Foundation Grant GB-1472. 相似文献
Zusammenfassung Extrazelluläre elektrophysiologische Erregungsableitungen von Geruchsrezeptoren in den Antennen von Tabakschwärmer-Raupen (Manduca sexta (Johan.)) ergaben, daß die Zellen auf verschiedene Duftstoffe unterschiedlich mit Änderung der Latenzzeit, der Zunahmerate der Erregungsfrequenz, der Anpassungsrate sowie der Änderung der Frequenz-Zunahme und-Abnahme reagieren. Die sich daraus ergebenden Zeitmuster der Spike-Aktivität könnten als Code dienen und so die Unterscheidung zwischen verschiedenen Pflanzendüften ermöglichen.
This research was supported by National Science Foundation Grant GB-1472. 相似文献