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81.
A polyspecific antiserum against protein extracted from PSTV-infected tomato leaves was prepared and the IgGs were separated by affinity chromatography on a beaded cellulose adsorbent with an immobilized “healthy” antigen. The antibody not adsorbed entered into a preferential reaction with the antigen from PSTV-infected leaves as estimated by an enzyme-linked immunosorbent assay. The immunochemical reactions did not significantly exceed the control background, if antigens from tomato leaves infected with potato viruses X, Y and M were analyzed. By immunoblot technique we revealed, however, that several antigens not detected in healthy leaves appeared in the leaves infected either with PSTV or with viruses X and M. An accumulation of a major antigen having a molecular mass of about 70 kDa was observed in viroid-infected leaves only, suggesting the specificity for viroid infection. The antigen was found not to be an alkaline endoproteinase - the pathogenesis-related protein P-69. Some antigens with molecular masses approximately 38.0, 23.7 and 22 kDa, which occurred in PSTV-infected leaves and in healthy calluses, were not detectable in PSTV-infected calluses. No reaction exceeding the control level was observed using enzyme-linked immunosorbent assay for antigens from silver nitrate-treated tomato leaves, although such leaves showed symptoms similar to that caused by viroids.  相似文献   
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Summary All the five enzymes of urea synthesis and the formation of urea in vitro can already be demonstrated in human liver as early as the 9th week of fetal development. At this stage the activity of carbamoyl phosphate synthetase is the highest, whereas that of ornithine carbamoyltransferase is the lowest as compared to those in the adult. The kinetic parameters of the urea cycle enzymes are the same in fetal liver as in adult liver, except that the Km values of ornithine carbamoyltransferase for L-ornithine are 3.5 mM and 0.42 mM in the fetus and in adult liver, respectively.Urea formation in vivo seems to begin in the second half of fetal life, and a gradual increase can be detected in the activity of the enzymes of urea synthesis. The activity of ortnithine decarboxylase, the glutamine-dependent carbamoyl phosphate synthetase and aspartate carbamoyltransferase, however, changes in the opposite direction.The concentration of carbamoyl phosphate and aspartate remains constant, but that of ornithine gradually decreases during ontogenesis. The ornithine, carbamoyl phosphate and aspartate pools are probably utilized in the polyamine, pyrimidine and urea syntheses at varying rates.  相似文献   
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Tyrosinase and L-DOPA decarboxylase activities have been investigated during Bufo bufo development since catecholamines and melanin are formed from common substrates in homologous cells. Catecholamines first appear at stage 13 (neural plate), but tyrosinase, at a very low level, and L-DOPA decarboxylase are present throughout all of prior development. Hence, L-DOPA decarboxylase activity is not likely to be correlated with the control of catecholamine synthesis, although at stage 17 it is mainly localized in the nonneural part of the embryo. The distribution of young melanosomes and L-DOPA decarboxylase suggest a separation between melanogenesis and catecholamine synthesis.  相似文献   
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Male and female rats were treated with different high doses of adrenaline for five days. Their food and water intakes and body weights were recorded. A considerable sex-difference was found on the 5th day in body weights and plasma glucose concentrations. Males had higher plasma glucose and lost more weight than females. Females ate and drank more than males throughout the experiment. The adrenaline-sensitivity of females decreased by the third day but it did not change in males. These data suggest that females are able to activate mechanisms that compensate the effects of high adrenaline levels while males are not, or their compensatory mechanisms are less efficient.  相似文献   
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Gastric mucosal damage was produced by the intragastric administration of 96% ethanol or 0.6 M HCl. The cytoprotective doses of prostacyclin (PGI2) (5 micrograms/kg), atropine (0.025 mg/kg) or cimetidine (2.5 mg/kg) were given intraperitoneally 30 min before the administration of the necrotizing agents. The animals were killed 1 hr later. The number and severity of gastric mucosal lesions (ulcer) were recorded. At the time of the sacrifice of the animals, superoxide dismutase (SOD) was prepared from the gastric fundic mucosa and its activity was measured. It was found that PGI2 (5 micrograms/kg), atropine (0.025 mg/kg) and cimetidine (2.5 mg/kg) significantly decreased the number and severity of gastric mucosal lesions (ulcers) produced by the intragastric administration of 96% ethanol a 0.6 M HCl, PGI2, atropine, cimetidine, given in cytoprotective doses, significantly mounted the ethanol-induced increase of gastric mucosal SOD activity; PGI2, atropine, cimetidine, given them in cytoprotective doses significantly shunted the HCl-induced decrease of gastric mucosal SOD activity. It has been concluded that; chemically different cytoprotective agents (PGI2, atropine, cimetidine) give rise to similar tendencies in the changes of gastric mucosal SOD activity; both the significant decrease (in the ethanol-model) and the significant increase (in the HCl-model) of this enzyme seem to be involved in the development of gastric mucosal protection by PGI2, atropine and cimetidine.  相似文献   
87.
The molting process and body growth in Rhodnius prolixus (Hemiptera: Reduviidae) (Ståhl, 1859) are significantly influenced by the availability and quality of food. Based on the body weight of each stage, the present study provides estimates of a potential critical weight threshold required for molt initiation in R. prolixus. In addition, a new measure given by the area under the weight curve is proposed, which encapsulates both body weight and time. It is shown that this measure is consistent with the data, and allows the estimation of a pre‐refractory period (i.e. the time interval between the moment at which the critical weight threshold is reached and the moment when no further meals are accepted). The present analysis estimates the critical weight threshold as 1.6, 5.3, 12.9, 42.0 and 97.0 mg for stages 1–5, respectively, whereas the values of the area under the curve threshold as 5, 16, 31.2, 159.7 and 329.9 mg days for stages 1–5, respectively. The results of the present study confirm the existence of a weight‐dependent mechanism for the initiation of molting in R. prolixus.  相似文献   
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