Nutrient uptake by paddy during the main three stages of growth

Summary Uptake of mineral nutrients and production of carbohydrates by paddy during the vegetative, the reproductive, and the ripening stage of growth were determined in a pot experiment.From 59 to 84 per cent of the nutrients present in the ripe plants were absorbed between tillering and flowering. More than 90 per cent of the N and K, 80 per cent of the P and Ca, and 65 per cent of the Mg were absorbed prior to flowering, and the remainder after heading.More than 60 per cent of the carbohydrates present in the ripe stage was produced after flowering.     

Re-irradiation after stereotactic body radiotherapy for spine metastases from hepatocellular carcinoma: a case report

Modern radiotherapy machines with refinements in planning software and image-guidance apparatuses have made stereotactic body radiotherapy (SBRT) more widely available as an effective tool in the management of spine metastases. In conventional palliative radiotherapy, the aim has traditionally been pain relief and short-term local control. In contrast, SBRT aims to deliver an ablative dose to enhance local control, with a smaller number of fractions while sparing the organs at risk (OAR), especially the spinal cord. Recently, trials have asserted the role of spine SBRT as an effective modality for durable local control, in addition to achieving pain relief. The quality of evidence for spine SBRT data is maturing, while prospective published trials on re-irradiation SBRT in spine remain sparse. The purpose of the present case report is to share the challenges faced while salvaging a dorsal spine metastasis and ablating a new right adrenal metastatic lesion in proximity of the transplanted liver.     

Activation of c-Kit in dendritic cells regulates T helper cell differentiation and allergic asthma

Dendritic cells (DCs) are integral to the differentiation of T helper cells into T helper type 1 T(H)1, T(H)2 and T(H)17 subsets. Interleukin-6 (IL-6) plays an important part in regulating these three arms of the immune response by limiting the T(H)1 response and promoting the T(H)2 and T(H)17 responses. In this study, we investigated pathways in DCs that promote IL-6 production. We show that the allergen house dust mite (HDM) or the mucosal adjuvant cholera toxin promotes cell surface expression of c-Kit and its ligand, stem cell factor (SCF), on DCs. This dual upregulation of c-Kit and SCF results in sustained signaling downstream of c-Kit, promoting IL-6 secretion. Intranasal administration of antigen into c-Kit-mutant mice or neutralization of IL-6 in cultures established from the lung-draining lymph nodes of immunized wild-type mice blunted the T(H)2 and T(H)17 responses. DCs lacking functional c-Kit or those unable to express membrane-bound SCF secreted lower amounts of IL-6 in response to HDM or cholera toxin. DCs expressing nonfunctional c-Kit were unable to induce a robust T(H)2 or T(H)17 response and elicited diminished allergic airway inflammation when adoptively transferred into mice. Expression of the Notch ligand Jagged-2, which has been associated with T(H)2 differentiation, was blunted in DCs from c-Kit-mutant mice. c-Kit upregulation was specifically induced by T(H)2- and T(H)17-skewing stimuli, as the T(H)1-inducing adjuvant, CpG oligodeoxynucleotide, did not promote either c-Kit or Jagged-2 expression. DCs generated from mice expressing a catalytically inactive form of the p110delta subunit of phosphatidylinositol-3 (PI3) kinase (p110(D910A)) secreted lower amounts of IL-6 upon stimulation with cholera toxin. Collectively, these results highlight the importance of the c-Kit-PI3 kinase-IL-6 signaling axis in DCs in regulating T cell responses.     

Fitting periplasmic membrane fusion proteins to inner membrane transporters: mutations that enable Escherichia coli AcrA to function with Pseudomonas aeruginosa MexB

AcrAB-TolC from Escherichia coli is a multidrug efflux complex capable of transenvelope transport. In this complex, AcrA is a periplasmic membrane fusion protein that establishes a functional connection between the inner membrane transporter AcrB of the RND superfamily and the outer membrane channel TolC. To gain insight into the mechanism of the functional association between components of this complex, we replaced AcrB with its close homolog MexB from Pseudomonas aeruginosa. Surprisingly, we found that AcrA is promiscuous and can form a partially functional complex with MexB and TolC. The chimeric AcrA-MexB-TolC complex protected cells from sodium dodecyl sulfate, novobiocin, and ethidium bromide but failed with other known substrates of MexB. We next identified single and double mutations in AcrA and MexB that enabled the complete functional fit between AcrA, MexB, and TolC. Mutations in either the α-helical hairpin of AcrA making contact with TolC or the β-barrel domain lying on MexB improved the functional alignment between components of the complex. Our results suggest that three components of multidrug efflux pumps do not associate in an “all-or-nothing” fashion but accommodate a certain degree of flexibility. This flexibility in the association between components affects the transport efficiency of RND pumps.     

Perilipin Controls Lipolysis by Regulating the Interactions of AB-hydrolase Containing 5 (Abhd5) and Adipose Triglyceride Lipase (Atgl)

The mobilization of stored lipid by hormones is a fundamental function of fat cells, and there is strong evidence that perilipin (Plin), a lipid droplet scaffold, and adipose tissue triglyceride lipase (Atgl), a triglyceride-specific lipase, play critical roles. Previous work suggested that Abhd5, a protein activator of Atgl, coordinates with Plin in controlling basal and stimulated lipolysis; however, the underlying mechanism is controversial. The present experiments investigated protein trafficking and interactions among Plin, Atgl, and Abhd5 in live cells. The results demonstrate that Plin binds Abhd5 with high affinity and thereby suppresses the interaction of Abhd5 with Atgl. Sequestration of Abhd5 appears to a major mechanism by which Plin reduces basal lipolysis. Phosphorylation of Plin on serine 492 or serine 517 rapidly releases Abhd5 from Plin, allowing Abhd5 to directly interact with Atgl. Imaging experiments demonstrated that the Plin-dependent interaction of Abhd5 and Atgl occurs mainly, but not exclusively, on lipid droplets that contain Plin.     

Auto-FACE: An NMR Based Binding Site Mapping Program for Fast Chemical Exchange Protein-Ligand Systems

Background

Nuclear Magnetic Resonance (NMR) spectroscopy offers a variety of experiments to study protein-ligand interactions at atomic resolution. Among these experiments, N Heteronuclear Single Quantum Correlation (HSQC) experiment is simple, less time consuming and highly informative in mapping the binding site of the ligand. The interpretation of N HSQC becomes ambiguous when the chemical shift perturbations are caused by non-specific interactions like allosteric changes and local structural rearrangement. Under such cases, detailed chemical exchange analysis based on chemical shift perturbation will assist in locating the binding site accurately.

Methodology/Principal Findings

We have automated the mapping of binding sites for fast chemical exchange systems using information obtained from N HSQC spectra of protein serially titrated with ligand of increasing concentrations. The automated program Auto-FACE (Auto-FAst Chemical Exchange analyzer) determines the parameters, e.g. rate of change of perturbation, binding equilibrium constant and magnitude of chemical shift perturbation to map the binding site residues. Interestingly, the rate of change of perturbation at lower ligand concentration is highly sensitive in differentiating the binding site residues from the non-binding site residues. To validate this program, the interaction between the protein and the ligand BH3I-1 was studied. Residues in the hydrophobic BH3 binding groove of were easily identified to be crucial for interaction with BH3I-1 from other residues that also exhibited perturbation. The geometrically averaged equilibrium constant () calculated for the residues present at the identified binding site is consistent with the values obtained by other techniques like isothermal calorimetry and fluorescence polarization assays (). Adjacent to the primary site, an additional binding site was identified which had an affinity of 3.8 times weaker than the former one. Further NMR based model fitting for individual residues suggest single site model for residues present at these binding sites and two site model for residues present between these sites. This implies that chemical shift perturbation can represent the local binding event much more accurately than the global binding event.

Conclusion/Significance

Detail NMR chemical shift perturbation analysis enabled binding site residues to be distinguished from non-binding site residues for accurate mapping of interaction site in complex fast exchange system between small molecule and protein. The methodology is automated and implemented in a program called “Auto-FACE”, which also allowed quantitative information of each interaction site and elucidation of binding mechanism.     

Acyclovir-Polyethylene Glycol 6000 Binary Dispersions: Mechanistic Insights

The dissolution and subsequent oral bioavailability of acyclovir (ACY) is limited by its poor aqueous solubility. An attempt has been made in this work to provide mechanistic insights into the solubility enhancement and dissolution of ACY by using the water-soluble carrier polyethylene glycol 6000 (PEG6000). Solid dispersions with varying ratios of the drug (ACY) and carrier (PEG6000) were prepared and evaluated by phase solubility, in vitro release studies, kinetic analysis, in situ perfusion, and in vitro permeation studies. Solid state characterization was done by powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) analysis, and surface morphology was assessed by polarizing microscopic image analysis, scanning electron microscopy, atomic force microscopy, and nuclear magnetic resonance analysis. Thermodynamic parameters indicated the solubilization effect of the carrier. The aqueous solubility and dissolution of ACY was found to be higher in all samples. The findings of XRD, DSC, FTIR and NMR analysis confirmed the formation of solid solution, crystallinity reduction, and the absence of interaction between the drug and carrier. SEM and AFM analysis reports ratified the particle size reduction and change in the surface morphology in samples. The permeation coefficient and amount of ACY diffused were higher in samples in comparison to pure ACY. Stability was found to be higher in dispersions. The results suggest that the study findings provided clear mechanical insights into the solubility and dissolution enhancement of ACY in PEG6000, and such findings could lay the platform for resolving the poor aqueous solubility issues in formulation development.