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991.
Phytotoxicity originating from the anaerobic decomposition of couch grass rhizomes has been studied. Short chain aliphatic (acetic, propionic and butyric) acids appear to be mainly responsible but hexanoic, succinic, phenylacetic, cinnamic, p-coumaric, 4-hydroxyphenylpropionic and 3,4-dihydroxyphenylpropionic acids are also present in the phytotoxic solutions formed during the decomposition. 相似文献
992.
Roger C. Anderson Anthony E. Liberta Joseph Packheiser Melvin E. Neville 《Plant and Soil》1980,54(1):149-152
Summary In an incubation study addition of green manure caused a reduction in the ammonia volatilized initially from both sodic and reclaimed soils but extensive volatilization occurred from the sodic soil, amended with green manure, after the tenth day till the conclusion of the experiment after 9 weeks. Volatilization from the reclaimed soil was much less. There was a slight build up of organic carbon and ammoniacal nitrogen in both the soils though greater in the reclaimed soil. More of nitrate and nitrite accumulated in the sodic soil. 相似文献
993.
The presence of nuclear and mitochondrial uracil-DNA glycosylase in extracts of human KB cells 总被引:12,自引:6,他引:6
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Extracts of human KB cells contain detectable uracil-DNA glycosylase activity. The majority of the activity is located within the nuclear fraction, however we present evidence for the presence of identifiable uracil-DNA glycosylase activity associated with the mitochondrial fraction of these cells. 相似文献
994.
995.
David A. Ellwood Murray D. Mitchell Anne B.M. Anderson A.C. Turnbull 《Prostaglandins & other lipid mediators》1980,19(3)
A method of tissue superfusion has been used to measure
prostanoid production by the ovine cervix during late pregnancy and at parturition. In late pregnancy (105–135 days of gestation) cervical tissue produced relatively large amounts of prostaglandin E (PGE); in comparison, the production rates of prostaglandin F (PGF), 13, 14-dihydro-15-oxo-prostaglandin F (PGFM) and 6-oxo-prostaglandin F1α were generally low. Thromboxane B2 (TXB2) production was minimal and often unmeasurable. There were significant increases in the production rates of PGE and 6-oxo-PGF1α by cervical tissue taken immediately after delivery, when compared to late pregnancy. Mean production rates of PGE increased from 19.8 ± 4.1 to 43.8 ± 7.4 ng/g. dry wt./min; 6-oxo-PGF1α production rates increased more than three-fold from 10.0 ± 2.7 to 34.6 ± 9.8 ng/g. dry wt./min (means ± S.E.M.). There were no significant differences in the rates of production of PGF, PGFM and TXB2 by the two groups. 相似文献
996.
997.
A total of 113 non-surgically collected bovine embryos, 5-8 days of age, were stored for 48 hours at 4 degrees C in a modified phosphate-buffered saline solution (PBS). Following storage, embryos were cultured for 8-12 hours at 37 degrees C, and those which were morphologically normal were transferred to synchronized recipients by several methods designed to achieve twin pregnancies. Embryos which were collected and transferred on the same day served as controls. Of 113 embryos stored, 47 (42%) appeared to be transferable after the brief culture period. There was a marked breed effect on viability after refrigeration, with Hereford embryos surviving significantly better than Angus embryos (71% vs. 12%, respectively, p < .001). Post-transfer embryo survival of stored and control embryos, based on actual calvings, was 34 and 48 percent, respectively, a difference which was not significant (p=0.3). A marked difference in pregnancy rate following non-surgical transfer by 2 different technicians was noted (50% vs. 21.7%, respectively). 相似文献
998.
999.
Showdomycin inhibited pig brain ( with pseudo first-order kinetics. The rate of inhibition by showdomycin was examined in the presence of 16 combinations of four ligands, i.e., Na+, K+, Mg2+ and ATP, and was found to depend on the ligands added. Combinations of ligands were divided into five groups in terms of the magnitude of the rate constant; in the order of decreasing rate constants these were: (1), (2) , , and none, (3) , and , (4) and , , , and ATP. The highest rate was obtained in the presence of Na+, Mg2+ and ATP. The apparent concentrations of Na+, Mg2+ and ATP for half-maximum stimulation of inhibition () were 3 mM, 0.13 mM and 4μM, respectively. The rate was unchanged upon further increase in Na+ concentration from 140 to 1000 mM. The rates of inhibition could be explained on the basis of the enzyme forms present, including E1, E2, ES, E1-P and E2-P, i.e., E2 has higher reactivity with showdomycin than E1, while E2-P has almost the same reactivity as E1-P. We conclude that the reaction of ( proceeds via at least four kinds of enzyme form (E1, E2, E1 · nucleotide and EP), which all have different conformations. 相似文献
1000.
We investigated the effects of exogenous cyclic GMP and stimulants of endogenous cyclic GMP accumulation on L-form (hepatic) pyruvate kinase (ATP: pyruvate 2-O-phosphotransferase, EC 2.7.1.40) activity in isolated rat hepatocytes. Exogenous cyclic GMP (200 muM) reduced pyruvate kinase activity, but was less potent than exogenous cyclic AMP (50 muM) (Ki congruent to 120 muM vs. 30 muM, respectively), had a slower onset of action (1.0 vs. 0.3 min, respectively) and a less rapid maximal effect (5.0 vs. 1.0 min, respectively). Similar results were noted with dibutyryl cyclic GMP or dibutyryl cyclic AMP. 1.0 muM acetylcholine increased cyclic GMP concentrations in isolated hepatocytes from 233 +/- 16 to 447 +/- 3 pmol/g cell protein (P less than 0.001), but did not alter pyruvate kinase activity. Similar results were noted with carbamylcholine, NaN3 or acetylcholine plus eserine sulfate. The results suggest a differential effect of exogenous vs. endogenous cyclic GMP on L-form pyruvate kinase activity, and question the physiological relevance of observations with exogenous cyclic GMP in this system. 相似文献