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1.
Abhishek Chatterjee Celia Caballero-Franco Dannika Bakker Stephanie Totten Armando Jardim 《The Journal of biological chemistry》2015,290(42):25579-25594
Enterohemorrhagic Escherichia coli is a causative agent of gastrointestinal and diarrheal diseases. Pathogenesis associated with enterohemorrhagic E. coli involves direct delivery of virulence factors from the bacteria into epithelial cell cytosol via a syringe-like organelle known as the type III secretion system. The type III secretion system protein EspD is a critical factor required for formation of a translocation pore on the host cell membrane. Here, we show that recombinant EspD spontaneously integrates into large unilamellar vesicle (LUV) lipid bilayers; however, pore formation required incorporation of anionic phospholipids such as phosphatidylserine and an acidic pH. Leakage assays performed with fluorescent dextrans confirmed that EspD formed a structure with an inner diameter of ∼2.5 nm. Protease mapping indicated that the two transmembrane helical hairpin of EspD penetrated the lipid layer positioning the N- and C-terminal domains on the extralumenal surface of LUVs. Finally, a combination of glutaraldehyde cross-linking and rate zonal centrifugation suggested that EspD in LUV membranes forms an ∼280–320-kDa oligomeric structure consisting of ∼6–7 subunits. 相似文献
2.
Summary Two varieties of tomato (Pusa Rubi and Selection 120) positively responded to algal inoculation in terms of the yield of fruits and shoots, but there was no significant effect on the vitamin C content of the fruits. A combined application of urea and algae was more effective than the application of urea alone. 相似文献
3.
The isolated blood-perfused lung preparation is widely used to visualize and define signaling in single microvessels. By coupling this preparation with real time imaging, it becomes feasible to determine permeability changes in individual pulmonary microvessels. Herein we describe steps to isolate rat lungs and perfuse them with autologous blood. Then, we outline steps to infuse fluorophores or agents via a microcatheter into a small lung region. Using these procedures described, we determined permeability increases in rat lung microvessels in response to infusions of bacterial lipopolysaccharide. The data revealed that lipopolysaccharide increased fluid leak across both venular and capillary microvessel segments. Thus, this method makes it possible to compare permeability responses among vascular segments and thus, define any heterogeneity in the response. While commonly used methods to define lung permeability require postprocessing of lung tissue samples, the use of real time imaging obviates this requirement as evident from the present method. Thus, the isolated lung preparation combined with real time imaging offers several advantages over traditional methods to determine lung microvascular permeability, yet is a straightforward method to develop and implement. 相似文献
4.
A postprandial increase in ammonia nitrogen excretion and oxygen consumption rates was observed in juvenile pike fed a natural diet or an artificial dry diet. Specific growth rate of natural diet fed pike (2.4%) was lower than that of pike fed the artificial diet (3.1%). Fifty per cent of ingesta was evacuated within 5–6 h in pike of 25 mg body weight and 9–10 h in those weighing 150mg. Daily nitrogen excretion rates were related to body weight. Respiratory quotient and energy retention efficiency were affected by the nature of the diet ingested by pike. Parameters of the energy balance (losses, retention, increment due to feeding) were related to energy intake. 相似文献
5.
Patterns of oxygen consumption, ammonia and urea excretion were monitored during late embryogenesis, i.e. 5 days before mass hatching and 12 days during the free-swimming stage of whitefish larvae, Coregonus lavaretus. Oxygen consumption increased from 1.31 to 2.53 mgO2 h−1 × 103 eggs−1 at hatching. Fasted, free-swimming larvae showed increasing oxygen consumption to the tenth day after hatching when it reached 5.52 mgO2 h−1 × 103 larvae−1 . Ammonia and urea excretion increased during pre-hatching period from 52.1 to 163.2 and 26.8 to 51.4 μgh−1 × 103 eggs−1 , respectively. The nitrogen excretion rate increased between the sixth and tenth day of fasting, i.e. for ammonia from 117.7 to 160.9 and for urea from 35.8 to 52.5 μg h−1 × 103 larvae−1 . Cumulative data on nitrogen and energy metabolism indicated that during late embryogenesis, and up to the fifth day after hatching, protein dominated in the energy expenditure. During the free swimming stage, the ratio of fat to protein in energy expenditure rose from 0.86 to 1.99. Combined data for several fish species indicated high dependance of oxygen uptake during the hatching period on egg size and temperature. 相似文献
6.
Identification of a new V kappa gene family that is highly expressed in hybridomas from an autoimmune mouse strain 总被引:2,自引:0,他引:2
R Shefner R Mayer A Kaushik P D'Eustachio C Bona B Diamond 《Journal of immunology (Baltimore, Md. : 1950)》1990,145(5):1609-1614
We have identified a new murine V kappa family that contains five to seven members, one member of which encodes the L chain V region of an anti-dsDNA antibody produced by a BALB/c hybridoma, C8.5. The cloned C8.5 V kappa gene exhibits highest homology with a human V kappa gene that was cloned from a nonproductive rearrangement but has never been seen in an expressed repertoire. Because this family was first identified in an autoantibody, we studied its expression in an autoimmune mouse strain. This V kappa family is expressed in 20% of hybridomas from NZB mice. 相似文献
7.
Sukriti Sacher Abhishek Mukherjee Arjun Ray 《Biological reviews of the Cambridge Philosophical Society》2023,98(4):1160-1183
Atherosclerosis is a major contributor to the onset and progression of cardiovascular disease (CVD). Cholesterol-loaded foam cells play a pivotal role in forming atherosclerotic plaques. Induction of cholesterol efflux from these cells may be a promising approach in treating CVD. The reverse cholesterol transport (RCT) pathway delivers cholesteryl ester (CE) packaged in high-density lipoproteins (HDL) from non-hepatic cells to the liver, thereby minimising cholesterol load of peripheral cells. RCT takes place via a well-organised interplay amongst apolipoprotein A1 (ApoA1), lecithin cholesterol acyltransferase (LCAT), ATP binding cassette transporter A1 (ABCA1), scavenger receptor-B1 (SR-B1), and the amount of free cholesterol. Unfortunately, modulation of RCT for treating atherosclerosis has failed in clinical trials owing to our lack of understanding of the relationship between HDL function and RCT. The fate of non-hepatic CEs in HDL is dependent on their access to proteins involved in remodelling and can be regulated at the structural level. An inadequate understanding of this inhibits the design of rational strategies for therapeutic interventions. Herein we extensively review the structure–function relationships that are essential for RCT. We also focus on genetic mutations that disturb the structural stability of proteins involved in RCT, rendering them partially or completely non-functional. Further studies are necessary for understanding the structural aspects of RCT pathway completely, and this review highlights alternative theories and unanswered questions. 相似文献
8.
Anthony John Pastore Alvaro Montoya Manasi Kamat Kari B. Basso James S. Italia Abhishek Chatterjee Maria Drosou Dimitrios A. Pantazis Alexander Angerhofer 《Protein science : a publication of the Protein Society》2023,32(1):e4537
Oxalate decarboxylase from Bacillus subtilis is a binuclear Mn-dependent acid stress response enzyme that converts the mono-anion of oxalic acid into formate and carbon dioxide in a redox neutral unimolecular disproportionation reaction. A π-stacked tryptophan dimer, W96 and W274, at the interface between two monomer subunits facilitates long-range electron transfer between the two Mn ions and plays an important role in the catalytic mechanism. Substitution of W96 with the unnatural amino acid 5-hydroxytryptophan leads to a persistent EPR signal which can be traced back to the neutral radical of 5-hydroxytryptophan with its hydroxyl proton removed. 5-Hydroxytryptophan acts as a hole sink preventing the formation of Mn(III) at the N-terminal active site and strongly suppresses enzymatic activity. The lower boundary of the standard reduction potential for the active site Mn(II)/Mn(III) couple can therefore be estimated as 740 mV against the normal hydrogen electrode at pH 4, the pH of maximum catalytic efficiency. Our results support the catalytic importance of long-range electron transfer in oxalate decarboxylase while at the same time highlighting the utility of unnatural amino acid incorporation and specifically the use of 5-hydroxytryptophan as an energetic sink for hole hopping to probe electron transfer in redox proteins. 相似文献
9.
L. S. Kaushik D. P. Singh R. S. Paroda 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1984,68(6):487-491
Summary The data from an experiment in cotton consisting of three testers and 12 lines selected deliberately have been analysed. The investigation showed higher specific combining ability variance for yield of seed cotton and number of bolls, indicating the predominance of non-additive gene action. Of parental lines, H777 was found to possess high g.c.a. effects for seed cotton yield, number of bolls and number of sympodes. Parent H842 contributed only for boll weight, whereas H655 was good general combiner for number of monopodes. There appeared to be better chances for increasing the yield by exploiting hybrid vigour for the number of bolls and boll weight. The presence of marked non-additive gene effects, in addition to additive gene effects, indicated the need for exploiting both the fixable and non-fixable components of genetic variance for increasing productivity in cotton. 相似文献
10.
A simple system for the Collection of Leaf-Derived Faecal Pellets of Aquatic Invertebrates 总被引:1,自引:1,他引:0
Animals and food (leaves) are confined at a desired temperature in a feeding chamber in the upper portion of the water column of a collector system. Egested material collects in water at 0°C also eliminates coprophagy and physical damage to the pellets. 相似文献