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41.
In this contribution, we have studied the dynamics of electron transfer (ET) of a flavoprotein to the bound cofactor, an important metabolic process, in a model molecular/macromolecular crowding environments. Vitamin B2 (riboflavin, Rf) and riboflavin binding protein (RBP) are used as model cofactor and flavoprotein, respectively. An anionic surfactant sodium dodecyl sulfate (SDS) is considered to be model crowding agent. A systematic study on the ET dynamics in various SDS concentration, ranging from below critical micellar concentration (CMC), where the surfactants remain as monomeric form to above CMC, where the surfactants self-assemble to form nanoscopic micelle, explores the dynamics of ET in the model molecular and macromolecular crowding environments. With energy selective excitation in picosecond-resolved studies, we have followed temporal quenching of the tryptophan residue of the protein and Rf in the RBP–Rf complex in various degrees of molecular/macromolecular crowding. The structural integrity of the protein (secondary and tertiary structures) and the vitamin binding capacity of RBP have been investigated using various techniques including UV–Vis, circular dichroism (CD) spectroscopy and dynamic light scattering (DLS) studies in the crowding environments. Our finding suggests that the effect of molecular/macromolecular crowding could have major implication in the intra-protein ET dynamics in cellular environments. 相似文献
42.
Patra K Bose S Sarkar S Rakshit J Jana S Mukherjee A Roy A Mandal DP Bhattacharjee S 《Chemico-biological interactions》2012,195(3):231-239
Cinnamic acid (C9H8O2), is a major constituent of the oriental Ayurvedic plant Cinnamomum cassia (Family: Lauraceae). This phenolic acid has been reported to possess various pharmacological properties of which its antioxidant activity is a prime one. Therefore it is rational to hypothesize that it may ameliorate myelosuppression and oxidative stress induced by cyclophosphamide, a widely used chemotherapeutic agent. Commercial cyclophosphamide, Endoxan, was administered intraperitoneally to Swiss albino mice (50mg/kg) pretreated with 15, 30 and 60mg/kg doses of cinnamic acid orally at alternate days for 15days. Cinnamic acid pre-treatment was found to reduce cyclophosphamide induced hypocellularity in the bone marrow and spleen. This recovery was also reflected in the peripheral blood count. Amelioration of hypocellularity could be correlated with the modulation of cell cycle phase distribution. Cinnamic acid pre-treatment reduced bone marrow and hepatic oxidative stress as evident by lipid peroxidation and activity assays of antioxidant enzymes such as superoxide dismutase, catalase and glutathione-S-transferase. The present study indicates that cinnamic acid pretreatment has protective influence on the myelosuppression and oxidative stress induced by cyclophosphamide. This investigation is an attempt and is the first of its kind to establish cinnamic acid as an agent whose consumption provides protection to normal cells from the toxic effects of a widely used anti-cancer drug. 相似文献
43.
Tatini Rakshit Subhadip Senapati Satyabrata Sinha A. M. Whited Paul S.-H. Park 《PloS one》2015,10(10)
Rhodopsin forms nanoscale domains (i.e., nanodomains) in rod outer segment disc membranes from mammalian species. It is unclear whether rhodopsin arranges in a similar manner in amphibian species, which are often used as a model system to investigate the function of rhodopsin and the structure of photoreceptor cells. Moreover, since samples are routinely prepared at low temperatures, it is unclear whether lipid phase separation effects in the membrane promote the observed nanodomain organization of rhodopsin from mammalian species. Rod outer segment disc membranes prepared from the cold-blooded frog Xenopus laevis were investigated by atomic force microscopy to visualize the organization of rhodopsin in the absence of lipid phase separation effects. Atomic force microscopy revealed that rhodopsin nanodomains form similarly as that observed previously in mammalian membranes. Formation of nanodomains in ROS disc membranes is independent of lipid phase separation and conserved among vertebrates. 相似文献
44.
Dr. P. Padmini Dr. S. K. Rakshit Dr. A. Baradarajan 《Bioprocess and biosystems engineering》1993,9(2-3):103-106
A change of the reaction rate was observed for the lipasecatalysed hydrolysis of ricebran oil in a batch stirred tank reactor using immobilized lipase enzyme as compared to free enzyme. The reactor rate was observed to be controlled mainly by factors like temperature, pH, initial enzyme concentration, initial substrate concentration and initial products concentration. 相似文献
45.
S. P. Sinhamahapatra S. C. Rakshit 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1981,60(3):141-143
Summary Morphologically similar leaf characters of two X-ray induced and independently isolated jute mutants from a common mother cultivar, JRO-632, were controlled by the same locus. However, they differed significantly in such quantitative characters as plant height, middle diameter, days to flower, node number and fibre yield/plant. Combining ability analysis from a 9 X 9 diallel set of crossing including these two mutants revealed that the mutants significantly differed in general combining ability (gca) effects for most of the traits in either direction or magnitude. Specific combining ability (sca) effects of the inter-mutant cross, as well as crosses with the common mother cultivar, JRO-632, also differed for most of the traits studied. It was suggested that X-irradiation induced random mutations effecting changes in the common background genotype, independent of the mutated locus. 相似文献
46.
A lipopolysaccharide mutant of Bradyrhizobium japonicum that uncouples plant from bacterial differentiation. 总被引:6,自引:0,他引:6
G Stacey J S So L E Roth B Lakshmi SK R W Carlson 《Molecular plant-microbe interactions : MPMI》1991,4(4):332-340
The Tn5-containing fragment from a non-nodulating mutant of Bradyrhizobium japonicum, strain ML142, was introduced into B. japonicum strain 61A101c by marker exchange to construct strain JS314. Strain JS314 failed to nodulate several soybean varieties tested. However, on a few varieties nodulelike structures were induced to a frequency of 54% of the plants inoculated. The ultrastructure of these nodules was studied in detail by light and electron microscopy. The nodules were devoid of internal bacteria, possessed central vascular tissue (unlike the lateral vascular tissue of a normal nodule), and exhibited localized cell death of epidermal cells. Study of the cell surface polysaccharides of strain JS314 revealed that the exopolysaccharide of this strain was identical to that of the wild type. However, the lipopolysaccharide (LPS) of strain JS314 showed gross differences from that isolated from the wild-type strain. Specifically, the LPS of strain JS314 appeared to lack the high molecular weight LPS I form, strongly suggesting that the LPS lacks the O-chain. Glycosyl-composition analysis showed that the LPS of mutant JS314 lacked 2,3-di-O-methylrhamnose, 3-O-methylrhamnose, fucose, and quinovosamine. These results indicate that LPS I in B. japonicum is essential for bacterial infection of soybean, but is not required to initiate plant cortical cell division, an early plant response to infection. 相似文献
47.
Metabolism of cationized lipoproteins by human fibroblasts: biochemical and morphologic correlations 下载免费PDF全文
Human plasma low density lipoprotein (LDL) that had been rendered polycationic by coupling with N, N-dimethyl-1, 3-propanediamine (DMPA) was shown by electron microscopy to bind in clusters to the surface of human fibroblasts. The clusters resembled those formed by polycationic ferritin (DMPA-feritin), a visual probe that binds to anionic site on the plasma membrane. Biochemical studies with (125)I-labeled DMPA-LDL showed that the membrane-bound lipoprotein was internalized and hydrolyzed in lysosomes. The turnover time for cell bound (125)I-DMPA-LDL, i.e., the time in which the amount of (125)I-DMPA-LDL degraded was equal to the steady-state cellular content of the lipoprotein, was about 50 h. Because the DMPA-LDL gained access to fibroblasts by binding nonspecifically to anionic sites on the cell surface rather than by binding to the physiologic LDL receptor, its uptake failed to be regulated under conditions in which the uptake of native LDL was reduced by feedback suppression of the LDL receptor. As a result, unlike the case with native LDL, the DMPA-LDL accumulated progressively within the cell, and this led to a massive increase in the cellular content of both free and esterified cholesterol. Studies with (14)C-oleate showed that at least 20 percent of the accumulated cholesteryl esters represented cholesterol that had been esterified within the cell. After 4 days of incubation with 10 μg/ml of DMPA-LDL, fibroblasts had accumulated so much cholesteryl ester that neutral lipid droplets were visible at the light microscope level with Oil Red O staining. By electron microscopy, these intracellular lipid droplets were observed to lack a tripartite limiting membrane. The ability to cause the overaccumulation of cholesteryl esters within cells by using DMPA-LDL provides a model system for study of the pathologic consequences at the cellular level of massive deposition of cholesteryl ester. 相似文献
48.
Srabanti Rakshit Jayashree Bagchi Labanya Mandal Kausik Paul Dipyaman Ganguly Sandip Bhattacharjee Monidipa Ghosh Nabendu Biswas Utpal Chaudhuri Santu Bandyopadhyay 《Apoptosis : an international journal on programmed cell death》2009,14(3):298-308
Introduction Imatinib, a small-molecule inhibitor of the Bcr-Abl kinase, is a successful drug for treating chronic myeloid leukemia (CML).
Bcr-Abl kinase stimulates the production of H2O2, which in turn activates Abl kinase. We therefore evaluated whether N-acetyl cysteine (NAC), a ROS scavenger improves imatinib efficacy.
Materials and methods Effects of imatinib and NAC either alone or in combination were assessed on Bcr-Abl+ cells to measure apoptosis. Role of nitric oxide (NO) in NAC-induced enhanced cytotoxicity was assessed using pharmacological
inhibitors and siRNAs of nitric oxide synthase isoforms. We report that imatinib-induced apoptosis of imatinib-resistant and
imatinib-sensitive Bcr-Abl+ CML cell lines and primary cells from CML patients is significantly enhanced by co-treatment with NAC compared to imatinib
treatment alone. In contrast, another ROS scavenger glutathione reversed imatinib-mediated killing. NAC-mediated enhanced
killing correlated with cleavage of caspases, PARP and up-regulation and down regulation of pro- and anti-apoptotic family
of proteins, respectively. Co-treatment with NAC leads to enhanced production of nitric oxide (NO) by endothelial nitric oxide
synthase (eNOS). Involvement of eNOS dependent NO in NAC-mediated enhancement of imatinib-induced cell death was confirmed
by nitric oxide synthase (NOS) specific pharmacological inhibitors and siRNAs. Indeed, NO donor sodium nitroprusside (SNP)
also enhanced imatinib-mediated apoptosis of Bcr-Abl+ cells.
Conclusion NAC enhances imatinib-induced apoptosis of Bcr-Abl+ cells by endothelial nitric oxide synthase-mediated production of nitric oxide. 相似文献
49.
Sujay Rakshit Zerka Rashid J. C. Sekhar T. Fatma Sain Dass 《Plant Cell, Tissue and Organ Culture》2010,100(1):31-37
Callus induction and regeneration ability of five elite maize inbred lines, CM 111, CM 117, CM 124, CM 125 and CM 300 were
investigated using 14-day-old immature embryos as explants. Genotype, medium, source of auxin and their concentrations influenced
induction of callus. Explants grown on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid at
1 mg l−1 showed the highest frequency of callusing. Among all the media tested, explants grown on N6 medium gave the highest frequency
of organogenic callus. Moreover, N6 supplemented with Dicamba promoted higher callus response in terms of both frequency of
induction as well as quality, compared to N6 medium with 2,4-D. N6 supplemented with 2 mg l−1 Dicamba induced the highest frequency of organogenic callus. Among the five genotypes tested, CM 124, CM 125, and CM 300
gave the best callus. Explants of both CM 124 and CM 300 incubated on MS medium supplemented with 1 mg l−1 benzyladenine and 0.5 mg l−1 indole acetic acid promoted the highest frequency of shoot induction. Though CM 124 induced higher percentage of shoot formation
than CM 300, the mean number of developed shoots per explant was higher for CM 300. The highest frequency of root formation
was observed when shoots were grown on MS medium supplemented with 2 mg l−1 naphathalene acetic acid. Percentage of regenerated plants ranged from 54 to 66. 相似文献
50.
Arunita Rakshit S. Rakshit J. Singh S. K. Chopra H. S. Balyan P. K. Gupta Shripad R. Bhat 《Journal of genetics》2010,89(2):155-162
Molecular markers linked to QTL contributing to agronomic and fibre quality traits would be useful for cotton improvement.
We have attempted to tag yield and fibre quality traits with AFLP and SSR markers using F2 and F3 populations of a cross between two Gossypium hirsutum varieties, PS56-4 and RS2013. Out of 50 AFLP primer combinations and 177 SSR primer pairs tested, 32 AFLP and four SSR primers
were chosen for genotyping F2 individuals. Marker-trait associations were studied for eight agronomic and five fibre quality traits through simple and
multiple regression analysis (MRA) using a set of 92 AFLP polymorphic loci and four SSR markers. Simple linear regression
analysis (SLRA) identified 23 markers for eight different traits whereas multiple regression analysis identified 30 markers
for at least one of the 13 traits. SSR marker BNL 3502 was consistently identified to be associated with fibre strength. While
all the markers identified in SLRA were also detected in MRA, as many as 16 of the 30 markers were identified to be associated
with respective traits in both F2 and F3 generations. The markers explained up to 41 per cent of phenotypic variation for individual traits. A number of markers were
found to be associated with multiple traits suggesting clustering of QTLs for fibre quality traits in cotton. 相似文献