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321.
Parveen Akhtar Márta Dorogi Krzysztof Pawlak László Kovács Attila Bóta Teréz Kiss Gy?z? Garab Petar H. Lambrev 《The Journal of biological chemistry》2015,290(8):4877-4886
Extraction of plant light-harvesting complex II (LHCII) from the native thylakoid membrane or from aggregates by the use of surfactants brings about significant changes in the excitonic circular dichroism (CD) spectrum and fluorescence quantum yield. To elucidate the cause of these changes, e.g. trimer-trimer contacts or surfactant-induced structural perturbations, we compared the CD spectra and fluorescence kinetics of LHCII aggregates, artificial and native LHCII-lipid membranes, and LHCII solubilized in different detergents or trapped in polymer gel. By this means we were able to identify CD spectral changes specific to LHCII-LHCII interactions, at (−)-437 and (+)-484 nm, and changes specific to the interaction with the detergent n-dodecyl-β-maltoside (β-DM) or membrane lipids, at (+)-447 and (−)-494 nm. The latter change is attributed to the conformational change of the LHCII-bound carotenoid neoxanthin, by analyzing the CD spectra of neoxanthin-deficient plant thylakoid membranes. The neoxanthin-specific band at (−)-494 nm was not pronounced in LHCII in detergent-free gels or solubilized in the α isomer of DM but was present when LHCII was reconstituted in membranes composed of phosphatidylcholine or plant thylakoid lipids, indicating that the conformation of neoxanthin is sensitive to the molecular environment. Neither the aggregation-specific CD bands, nor the surfactant-specific bands were positively associated with the onset of fluorescence quenching, which could be triggered without invoking such spectral changes. Significant quenching was not active in reconstituted LHCII proteoliposomes, whereas a high degree of energetic connectivity, depending on the lipid:protein ratio, in these membranes allows for efficient light harvesting. 相似文献
322.
Vivek Verma Surbhi Gupta Parveen Kumar Ankita Rawat Rakesh Singh Dhanda 《Preparative biochemistry & biotechnology》2013,43(6):616-622
AbstractUropathogenic E. coli (UPEC), especially associated with severe urinary tract infections (UTI) pathologies, harbors an important virulence factor known as α-hemolysin (110?kDa). Hemolytic activity of α-hemolysin (HlyA) requires modification (acylation) of two lysine residues of HlyA by HlyC, part of operon hlyCABD. Most of the previous studies had used whole operon hlyCABD and gene tolC cloning for the production of active α-hemolysin. Studies involving α-hemolysin are limited due to the cumbersome and manual method of purification for this toxin. Here, we report a simple method for production of both active and inactive recombinant α-hemolysin by cloning only hlyA and hlyC genes of operon hlyCABD. Presence of both active and inactive α-hemolysin would be advantageous for functional characterization. After translation, the yield of the purified α-hemolysin was 1?mg/200?ml. Functionality of the recombinant α-hemolysin protein was confirmed using hemolytic assay. This is the first report of the production of active and inactive recombinant α-hemolysin for functional studies. 相似文献
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324.
Kumari Neelam Nidhi Rawat Vijay K. Tiwari Sundip Kumar Parveen Chhuneja Kuldeep Singh Gursharn S. Randhawa Harcharan S. Dhaliwal 《Molecular breeding : new strategies in plant improvement》2011,28(4):623-634
Dietary deficiency of iron and zinc micronutrients affects more than two billion people worldwide. Breeding for micronutrient-dense
crops is the most sustainable and cost-effective approach for alleviation of micronutrient malnutrition. Three accessions
of Aegilops
peregrina (Hack.) Maire & Weill (2n = 28, UPUPSPSP), selected for high grain iron and zinc concentration were crossed with Triticum
aestivum L. cv. Chinese Spring (Ph
I
). The sterile F1 hybrids were backcrossed with elite wheat cultivars to get fertile BC2F2 derivatives. Some of the fertile BC2F2 derivatives showed nearly 100% increase in grain iron and more than 200% increase in grain zinc concentration compared to
the recipient wheat cultivars. The development of derivatives with significantly higher grain micronutrients, high thousand-grain
weight and harvest index suggests that the enhanced micronutrient concentration is due to the distinct genetic system of Ae. peregrina and not to the concentration effect. Genomic in situ hybridization, comparison of introgressed chromosomes with the standard
karyotype of Ae. peregrina and simple sequence repeat marker analysis revealed the introgression of 7SP chromosomes in five selected derivatives, 7UP in four, group 4 and 4SP in three and a translocated 5UP of Ae. peregrina in one of the selected derivatives. Molecular marker analysis using the introgressed chromosome markers indicated that two
of the BC2F3 progenies were stabilized as disomic addition lines. It could, therefore, be concluded that the group 4 and 7 chromosomes
of Ae. peregrina carry the genes for high grain iron and zinc concentration. 相似文献
325.
Mohammad Sikander Shabnam Malik Kehkashan Parveen Maqsood Ahmad Deepak Yadav Zubair Bin Hafeez Manish Bansal 《Protoplasma》2013,250(2):483-493
The effect of an aqueous extract of Origanum vulgare (OV) leaves extract on CCl4-induced hepatotoxicity was investigated in normal and hepatotoxic rats. To evaluate the hepatoprotective activity of OV, rats were divided into six groups: control group, O. vulgare group, carbon tetrachloride (CCl4; 2 ml/kg body weight) group, and three treatment groups that received CCl4 and OV at doses of 50, 100, 150 mg/kg body weight orally for 15 days. Alanine amino transferase (ALT), alkaline phosphatase (ALP), and aspartate amino transferase (AST) in serum, lipid peroxide (LPO), GST, CAT, SOD, GPx, GR, and GSH in liver tissue were estimated to assess liver function. CCl4 administration led to pathological and biochemical evidence of liver injury as compared to controls. OV administration led to significant protection against CCl4-induced hepatotoxicity in dose-dependent manner, maximum activity was found in CCl4?+?OV3 (150 mg/kg body weight) groups and changes in the hepatocytes were confirmed through histopathological analysis of liver tissues. It was also associated with significantly lower serum ALT, ALP, and AST levels, higher GST, CAT, SOD, GPx, GR, and GSH level in liver tissue. The level of LPO also decreases significantly after the administration of OV leaves extract. The biochemical observations were supplemented with histopathological examination of rat liver sections. Thus, the study suggests O. vulgare showed protective activity against CCl4-induced hepatotoxicity in Wistar rats and might be beneficial for the liver toxicity. 相似文献
326.
R. Mohamudha Parveen Subha Manivannan B. N. Harish S. C. Parija 《Indian journal of microbiology》2012,52(1):35-40
Data on CTX-M type extended-spectrum β-lactamase (ESBL) produced by Gram-negative bacteria by molecular methods are limited
from India. This study was conducted to investigate the prevalence of CTX-M type ESBL producing Escherichia coli and Klebsiella pneumoniae from nosocomial isolates in a tertiary care hospital in southern India. A total of 179 clinical isolates of K. pneumoniae (n = 72) and E. coli (n = 107) were obtained in a period of 3 months and assessed for ESBL production phenotypically. Associated resistance to
a panel of antibiotics and Minimum Inhibitory Concentration for 3rd generation cephalosporins was determined. Phenotypically
ESBL positive isolates were subjected to PCR for bla
CTX-M gene using two sets of primers for the simultaneous detection of all the five major groups of CTX-M types. All the positive
isolates were then subjected to a group specific PCR to detect the prevalent group. Out of 179 isolates, 156 (87.1%) were
positive for ESBL phenotypically, which includes 39.2% of K. pneumoniae and 60.8% of E. coli. All of them were examined by PCR using two primers for the presence of bla
CTX-M genes. Among the 156 phenotypic positive isolates, 124 (79.4%) were positive for bla
CTX-M genes, of which 45 (36.2%) were K. pneumoniae, 79 (63.7%) were E. coli. When the 124 positive clinical isolates were further tested with CTX-M group-specific primers, all were positive for the
CTX-M-1 group. Our findings document evidence of the high prevalence of multidrug resistant CTX-M group 1 type ESBL among
nosocomial isolates in this region. High co-resistance to other non-β-lactam antibiotics is a major challenge for management
of ESBL infections. This is alarming and calls for the judicious use of carbapenems, especially in developing countries. This
has significant implications for patient management, and indicates the need for increased surveillance and for further molecular
characterization of these isolates. 相似文献
327.
328.
Soybean is extensively cultivated worldwide and is the largest source of biologically fixed nitrogen among legumes. It is nodulated by both slow and fast growing rhizobia. Indigenous soybean rhizobia in Vertisols of central India were assessed for utilization of 35 carbon sources and intrinsic resistance to 19 antibiotics. There was greater utilization of trehalose and raffinose by fast growers (87 and 73 % by fast vs. 35 and 30 % by slow growers); but slow growers had higher ability to utilize glucosamine (75 % by slow vs. 33 % by fast growers). A larger proportion of slow growers were resistant to vancomycin, polymyxin-B and rifampicin (70, 65 and 55 %) compared to fast growers (13, 7 and 7 % each). Among the two 16S rRNA sequence types in the slow growers, those belonging to Bradyrhizobium spp. utilized glucosamine while those belonging to Rhizobium radiobacter did not. All the fast growers had 16S rRNA homology to R. radiobacter and majority could not utilize glucosamine. It is suggested that during initial isolations and screening of rhizobia in strain selection programmes, using carbon sources like glucosamine and antibiotics like vancomycin, polymyxin-B and rifampicin in the media may provide a simple way of distinguishing Bradyrhizobium strains from R. radiobacter among the slow growers. 相似文献
329.
330.
Previous work from this laboratory has shown that isolated chick renal proximal tubule cells possess an Na+-dependent Pi transport system and that Pi uptake is stimulated under gluconeogenic conditions. It is shown in the present paper that gluconeogenesis is associated with a rapid incorporation of Pi into membrane phospholipids, particularly phosphatidylinositol, and some evidence has been obtained for a change in the relative amounts of phosphatidylinositol polyphosphates under gluconeogenic conditions. There is no increase in the total phospholipid phosphate content however, suggesting that pyruvate-induced incorporation of Pi into phospholipids represents accelerated turnover rather than a net increase in synthesis. It is suggested that the stimulation of Na+-dependent Pi uptake by pyruvate is related to the increased rate of phospholipid turnover. Thus Pi transport may be a further example of a physiological system that is influenced by phosphatidylinositol metabolism. The role of phosphatidylinositol phosphates could be to stimulate transfer of transporter molecules from internal stores to the brush-border membrane of the cell. 相似文献