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1.
Sharbati R. Singh Sunita Dalal Rohtas Singh A. K. Dhawan Rajwant K. Kalia 《Journal of plant biochemistry and biotechnology.》2012,21(2):220-228
Effect of season, media type, carbon source, growth regulators and transplanting media on micropropagation of Dendrocalamus asper, an important bamboo species, was examined. The season of explant collection played an important role in axillary bud sprouting and spring (February?CApril) was found to be the best period for explant collection. Among the different media MS was found to be the best for micropropagation. Maximum numbers (4.83/explant) of shoots were initiated in MS?+?15???M BAP. For shoot multiplication, MS medium supplemented with 10???M BAP and 75???M Adenine sulfate was used. BAP was superior to KIN for both explant establishment, as well as, shoot multiplication. Optimal rooting was achieved in shoots cultured on ? strength MS medium supplemented with 5???M each of IBA and NAA. Regenerated plantlets were acclimatized and hardened in green house using dune sand and vermi-compost (3:1) with 92.34% success and transferred to the field with 100% survival rate. In the field, plants supplied with FYM along with urea showed better growth and development. Macroproliferation, plant multiplication by separating the rooted tillers of well established in vitro raised plantlets after 5 to 6?months of growth in the green house could double the multiplication rate. More than 25000 in vitro raised plants were successfully transferred to the field and no morphological variations in growth were observed, thus proving the potential of tissue culture for raising large scale plantations of D. asper. 相似文献
2.
Chromium (V) and hydroxyl radical formation during the glutathione reductase-catalyzed reduction of chromium (VI) 总被引:3,自引:0,他引:3
Electron spin resonance measurements provide evidence for the formation of long-lived Cr(V) intermediates in the reduction of Cr(VI) by glutathione reductase in the presence of NADPH and for the hydroxyl radical formation during the glutathione reductase catalyzed reduction of Cr(VI). Hydrogen peroxide suppresses Cr(V) and enhances the formation of hydroxyl radicals. Thus Cr(V) intermediates catalyze generation of hydroxyl radicals from hydrogen peroxide through a Fenton-like reaction. Thus the mechanism of Cr(VI) toxicity might involve the interaction between macromolecules and the hydroxyl radicals. 相似文献
3.
Electron spin resonance (ESR) measurements provide evidence for the formation of Cr(V) intermediates in the enzymatic reduction of Cr(VI) by glutathione reductase (GSSG-R) in the presence of NADPH, indicating an initial single-electron transfer step in the reduction mechanism. Depending on the pH, at least two different Cr(V) species are generated which are relatively long-lived. In addition, we have detected the hydroxyl (.OH) radical formation during the GSSG-R catalyzed reduction of Cr(VI) by spin trapping, employing 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) as spin traps. Superoxide dismutase (SOD) causes only a minor effect on the .OH radical and Cr(V) formation, indicating that the O2- is not significantly involved in the reaction mechanism. Catalase enhances the Cr(V) formation and substantially inhibits the .OH radical formation, indicating the involvement of hydrogen peroxide (H2O2) in the reaction mechanism. Addition of H2O2 suppresses Cr(V) and enhances the .OH radical formation. Measurements involving N-ethylmaleimide show that the Cr(V) species, produced enzymatically by the reduction of Cr(VI) by GSSG-R, react with H2O2 to generate .OH radicals, which might participate in the initiation of Cr(VI) carcinogenicity. 相似文献
4.
Fecundity of four species of catfishes, namely, Mystus seenghala (Sykes), Mystus cavasius (Ham), Wallagonia attu (Bloch) and Heteropneustes fossilis (Bloch), was studied. The fecundity of Mystus seenghala and Mystus cavasius varied between 20064 to 46443 and 3314 to 63135 respectively. In Wallagonia attu and Heteropneustes fossilis it varied between 66070 to 453148 and 1375 to 46737 respectively. In all the four species fecundity has a linear relationship
with body weight and gonad weight, and a parabolic relationship with length in all the fishes excepting Mystus seenghala, where it is linear. By subjecting the data to multiple regression analysis, it is observed that the fecundity of each species
can be most accurately determined by taking two variables together. In all the fishes studied the relative fecundity (Egg/body
wt.) does not change significantly either with length or body weight. 相似文献
5.
Effect of plant growth and addition of plant residues on the phosphatase activity in soil 总被引:1,自引:0,他引:1
R. C. Dalal 《Plant and Soil》1982,66(2):265-269
Summary The phosphatase activity of the soil amended with roots and tops of clover (Trifolium repens) plant material (0.1% by weight) remained essentially constant in the absence of growing plants but changed considerably in the presence of plants (Avena sativa) grown for 10 weeks. There was a significant relationship between the phosphatase activity and organic and inorganic P in the soil solution only in the presence of growing plants. The differences in phosphatase activity between roots and tops amended soil were attributed to total C as well as differences in the degree of availability of C added through plant materials. This may also apply to the carpet grass (Axonopus affinis) amended soil. 相似文献
6.
In the presence of hydrogen peroxide (H2O2), xanthine oxidase has been found to catalyze sulfur trioxide anion radical (SO3.-) formation from sulfite anion (SO3(2-)). The SO3.- radical was identified by ESR (electron spin resonance) spin trapping, utilizing 5,5-dimethyl-l-pyrroline-l-oxide (DMPO) as the spin trap. Inactivated xanthine oxidase does not catalyze SO3.- radical formation, implying a specific role for this enzyme. The initial rate of SO3.- radical formation increases linearly with xanthine oxidase concentration. Together, these observations indicate that the SO3.- generation occurs enzymatically. These results suggest a new property of xanthine oxidase and perhaps also a significant step in the mechanism of sulfite toxicity in cellular systems. 相似文献
7.
8.
Williams DC Wildung MR Jin AQ Dalal D Oliver JS Coates RM Croteau R 《Archives of biochemistry and biophysics》2000,379(1):137-146
The diterpene cyclase taxadiene synthase from yew (Taxus) species transforms geranylgeranyl diphosphate to taxa-4(5),11(12)-diene as the first committed step in the biosynthesis of the anti-cancer drug Taxol. Taxadiene synthase is translated as a preprotein bearing an N-terminal targeting sequence for localization to and processing in the plastids. Overexpression of the full-length preprotein in Escherichia coli and purification are compromised by host codon usage, inclusion body formation, and association with host chaperones, and the preprotein is catalytically impaired. Since the transit peptide-mature enzyme cleavage site could not be determined directly, a series of N-terminally truncated enzymes was created by expression of the corresponding cDNAs from a suitable vector, and each was purified and kinetically evaluated. Deletion of up to 79 residues yielded functional protein; however, deletion of 93 or more amino acids resulted in complete elimination of activity, implying a structural or catalytic role for the amino terminus. The pseudomature form of taxadiene synthase having 60 amino acids deleted from the preprotein was found to be superior with respect to level of expression, ease of purification, solubility, stability, and catalytic activity with kinetics comparable to the native enzyme. In addition to the major product, taxa-4(5),11(12)-diene (94%), this enzyme produces a small amount of the isomeric taxa-4(20), 11(12)-diene ( approximately 5%), and a product tentatively identified as verticillene ( approximately 1%). Isotopically sensitive branching experiments utilizing (4R)-[4-(2)H(1)]geranylgeranyl diphosphate confirmed that the two taxadiene isomers, and a third (taxa-3(4),11(12)-diene), are derived from the same intermediate taxenyl C4-carbocation. These results, along with the failure of the enzyme to utilize 2, 7-cyclogeranylgeranyl diphosphate as an alternate substrate, indicate that the reaction proceeds by initial ionization of the diphosphate ester and macrocyclization to the verticillyl intermediate, followed by a secondary cyclization to the taxenyl cation and deprotonation (i.e., formation of the A-ring prior to B/C-ring closure). Two potential mechanism-based inhibitors were tested with recombinant taxadiene synthase but neither provided time-dependent inactivation nor afforded more than modest competitive inhibition. 相似文献
9.
10.
Yogesh B. Wagh Kundan C. Tayade Anil Kuwar Suban K. Sahoo Mayank Narinder Singh Dipak S. Dalal 《Luminescence》2020,35(3):379-384
Abstract In this study, the recognition contour of Chemosensor 1 was investigated using semiaqueous methanol (XH, mole fraction = 0.31) for a range of anions and bioactive species. Host–receptor signalling based on the internal charge transfer mechanism for Chemosensor 1 was explored and reported. Structure of Chemosensor 1 and its plausible anion coordination based on hydrogen bonding is complemented with density functional theory. Consequently, we investigated the applicability of the synthesized probe in blood plasma, urine, tap water samples, and for monitoring of ATP in lysosomes by apyrase enzyme. 相似文献