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91.
The unambiguous measurement of intracellular sodium ion [Na+]i by the noninvasive NMR technique offers a new opportunity to monitor precisely the maintenance and fluctuations of [Na+]i levels in intact cells and tissues. The anionic frequency shift reagent, dysprosium (III) tripolyphosphate, which does not permeate intact cells, when added to suspensions of intact adult rat cardiac myocytes, alters the NMR frequency of extracellular sodium ions, [Na+]o, leaving that of intracellular ions, [Na+]i, unaffected. Using 23Na NMR in conjunction with this shift reagent, we have determined NMR-visible intracellular Na+ ion concentration in a suspension of isolated cardiac myocytes under standard conditions with insulin and Ca2+ in the extracellular medium to be 8.8 +/- 1.2 mmol/liter of cells (n = 4). This value is comparable to that measured by intracellular ion-selective microelectrodes in heart tissue. Cardiac myocytes incubated for several hours in insulin-deficient, Ca2+-containing medium prior to NMR measurement exhibited a somewhat lower [Na+]i value of 6.9 +/- 0.5 mmol/liter of cells (n = 3). Reversible Na+ loading of the cells by manipulation of extracellular calcium levels is readily measured by the NMR technique. Incubation of myocytes in a Ca2+-free, insulin-containing medium causes a 3-fold increase in [Na+]i to a level of 22.8 +/- 2.6 mmol/liter of cells (n = 10). In contrast to cells with insulin, insulin-deficient myocytes exhibit a markedly lower level of [Na+]i of only 14.6 +/- 2.0 mmol/liter of cells (n = 4) in Ca2+-free medium. These observations suggest that insulin may stimulate a pathway for Na+ influx in heart cells. 相似文献
92.
Dexamethasone-induced phospholipase A2-inhibitory proteins (PLIP) influenced by the H-2 histocompatibility region 总被引:1,自引:0,他引:1
C Gupta A S Goldman 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1985,178(1):29-35
Recent work has indicated that the H-2 histocompatibility complex on chromosome 17 influences the degree of glucocorticoid-induced teratogenicity and anti-inflammatory response. Since both of these hormonal actions appear to be mediated by the induction of phospholipase A2-inhibitory proteins (PLIP), the influence of the H-2 complex on the induction of PLIP by glucocorticoids in thymocytes and embryonic palates has been investigated. Analysis of dexamethasone-induced PLIP by Sephadex G-100 revealed four peaks of mol wt 55,000, 40,000, 28,000 and 15,000 in mouse thymocytes and from one to three of these PLIPs in mouse embryonic palates. The 55,000 mol wt PLIP comprised 50-60% of the total activity. The total amount of dexamethasone-induced PLIP is significantly higher in B10.A (H-2a) thymocytes than that in thymocytes of their congenic resistant partners, B10 (H-2b). The induced level of PLIP in the embryonic palates treated with dexamethasone is also significantly higher in the H-2a congenic strains with either the A or B background (AWy or B10.A) than that in their resistant partners (A.BY or B10). Thus, both susceptibility to glucocorticoid-induced cleft palate and the production of PLIP by this hormone are influenced by the H-2 complex. 相似文献
93.
Selection of diverse genotypes for heterosis in yield and response in toria (Brassica campestris L.)
Singh D. Gupta P. K. 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,69(5-6):515-517
Summary Thirty-one genotypes of toria (Brassica campestris L.) were grown in twelve environments and subsequently analysed in order to select potential parents which expressed diversity for both 12 different characters (estimated by Mahalanobis' D2 technique) and response to the environments (estimated on the basis of negative correlation between deviations in seed yield of a pair of genotypes from their respective environmental means). Coefficients of determination (r2) were also used to measure the reliability of correlation, which is the basis of diversity of response. Stability parameters (b and S2d) and mean seed yield were also considered in selecting potential parents. On the basis of these criteria, three pairs of genotypes (ITSA and TCSU-1, TCSU-7 and TH-8 and Ludhiana Composite-1 and TH-4) are recommended to be used as parents for hybridization programmes so that heterosis both in seed yield and response may be exploited. 相似文献
94.
Samuel H. K. Ho Uttam Das Gupta John S. Rieske 《Journal of bioenergetics and biomembranes》1985,17(5):269-282
Deformamidoazidoantimycin A (DAA), a photoactive derivative of antimycin A containing an azido group substituting for the formamido group attached to the phenyl ring, was synthesized. The ultraviolet spectrum of DAA was almost identical to that of antimycin A, indicating little alteration of the electronic structure of the substituted phenyl ring by the azido substitution. However, the inhibitory effectiveness of DAA toward ubiquinol-cytochromec reductase (Complex III) purified from bovine heart (K
i
=ca. 0.5 µM) was considerably less than that of antimycin (K
i
3 pM), indicating a direct rather than a supporting role of the formamido group in the inhibitory activity of antimycin. Exposure of purified Complex III to [3H]DAA plus ultraviolet light caused a major labeling by tritium of SDS-PAGE band 7 (m=13 kDa by SDS-PAGE) and lesser but significant labeling of bands 3, 6, 8, and 9. Pretreatment of Complex III with antimycin greatly suppressed the labeling of bands 5, 6, and 7 but caused an apparent increased labeling of bands 8 and 9 by [3H]DAA, respectively. The labeling of band 7 by [3H]DAA also was strongly suppressed by reduction of Complex III by either sodium borohybride or ascorbate. Based on magnitude of labeling by [3H]DAA and the degree of suppression of labeling by antimycin, the protein of band 7 qualified as the principal component for specific binding of antimycin with the protein of band 6 (m=16 kDa) showing a lesser but significant amount of specific binding. 相似文献
95.
Callus was successfully initiated on root, mesocotyl and leaf base segments of 3- to 4-day-old seedlings of ragi (Eleusine coracana Gaertn.). 2,4-D along with casein hydrolysate for Murashige and Skoog's basal medium was found to be most effective for callus initiation and maintenance. Mesocotyl and leaf base tissue derived calli gave shoot buds in medium in which the 2,4-D concentration was lowered. 相似文献
96.
Callus cultures were established from stem explants of Ruscus hypophyllum on a modified basal medium of Murashige and Skoog (1962) supplemented with 1 mg l-1 2,4-D+0.1 mg l-1 BAP. The optimal 2,4-D concentration for promoting shoot bud formation and growth was 0.05 mg l-1 along with 0.5 mg l-1 BAP. Sixty percent of rootless shoots produced flowers on the regenerating medium. Rooting was induced when shoots were transferred to half strength MS inorganic salts supplemented with 2 mg l-1 IBA. Eighty percent of plants transferred to soil have survived. 相似文献
97.
Sunil Palchaudhuri Ranajit Kumar Dipak Sen Ruma Pal Sajal Ghosh Banwarilal Sarkar Sujit K. Bhattacharya Sudhir C. Pal 《FEMS microbiology letters》1985,30(1-2):187-191
Abstract Multiple antibiotic-resistant Shigella dysenteriae type 1 isolates from a recent epidemic in West Bengal (India) showed identical plasmid patterns. All isolates were resistant to ampicillin (Am), chloramphenicol (Cm), tetracycline (Tc), streptomycin (Sm) and trimethoprim (Tp) and contained 6 plasmids, ranging from 2.5–120 kb. The Am resistance determinant was located on the 120 kb plasmid. This plasmid was unstable when the S. dysenteriae strains were grown above 37°C. The Bangladesh strains of S. dysenteriae type 1 showed identical plasmid patterns, except that many isolates were Am-sensitive and lacked the 120 kb plasmid. In strains from both Bangladesh and West Bengal, predominantly group-B plasmids conferred resistance to Cm and Tc. Comparisons of Eco R1 fragments generated from the total plasmid DNA content of each strain support the view that the plasmids present in the S. dysenteriae type 1 strains isolated from all recent epidemics in India and Bangladesh were identical. 相似文献
98.
Identification of a phosphoenolpyruvate:fructose 1-phosphotransferase system in Azospirillum brasilense 总被引:7,自引:4,他引:3
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An inducible phosphoenolpyruvate:fructose phosphotransferase system has been detected in Azospirillum brasilense, which requires a minimum of two components of the crude extracts for activity: (i) a soluble fraction (enzyme I) and (ii) a membrane fraction (enzyme II). The uninduced cells neither show any uptake of fructose nor express activity of either of these two enzyme fractions. C-1 of fructose is the site of phosphorylation. This phosphotransferase system does not accept glucose as a substrate for phosphorylation. 相似文献
99.
100.
Dacus cucurbitae is a serious pest of various types of fleshy fruits and vegetables. The mitotic and salivary chromosomes were reinvestigated using the air-drying and different (C-and H-) banding techniques with a view to rectify the existing controversy regarding the Indian populations of this species. A standard map of its salivary chromosomes was constructed and some important identifiable landmarks were recognized in each arm. 相似文献