Activity modulation and allosteric control of a scaffolded DNAzyme using a dynamic DNA nanostructure.

Recognition of the fundamental importance of allosteric regulation in biology dates back to not long after its discovery in the 1960s. Our ability to rationally engineer this potentially useful property into normally non-allosteric catalysts, however, remains limited. In response we report a DNA nanotechnology-enabled approach for introducing allostery into catalytic nucleic acids. Specifically, we have grafted one or two copies of a peroxidase-like DNAzyme, hemin-bound G-quadruplex (hemin-G), onto a DNA tetrahedral nanostructure in such a manner as to cause them to interact, modulating their catalytic activity. We achieve allosteric regulation of these catalysts by incorporating dynamically responsive oligonucleotides that respond to specific "effector" molecules (complementary oligonucleotides or small molecules), altering the spacing between the catalytic sites and thus regulating their activity. This designable approach thus enables subtle allosteric modulation in DNAzymes that is potentially of use for nanomedicine and nanomachines

Real-time visualization of clustering and intracellular transport of gold nanoparticles by correlative imaging.

Mechanistic understanding of the endocytosis and intracellular trafficking of nanoparticles is essential for designing smart theranostic carriers. Physico-chemical properties, including size, clustering and surface chemistry of nanoparticles regulate their cellular uptake and transport. Significantly, even single nanoparticles could cluster intracellularly, yet their clustering state and subsequent trafficking are not well understood. Here, we used DNA-decorated gold (fPlas-gold) nanoparticles as a dually emissive fluorescent and plasmonic probe to examine their clustering states and intracellular transport. Evidence from correlative fluorescence and plasmonic imaging shows that endocytosis of fPlas-gold follows multiple pathways. In the early stages of endocytosis, fPlas-gold nanoparticles appear mostly as single particles and they cluster during the vesicular transport and maturation. The speed of encapsulated fPlas-gold transport was critically dependent on the size of clusters but not on the types of organelle such as endosomes and lysosomes. Our results provide key strategies for engineering theranostic nanocarriers for efficient health management

Inhibition of the CXCL12/CXCR4-axis as preventive therapy for radiation-induced pulmonary fibrosis

Background: A devastating late injury caused by radiation is pulmonary fibrosis. This risk may limit the volume of irradiation and compromise potentially curative therapy. Therefore, development of a therapy to prevent this toxicity can be of great benefit for this patient population. Activation of the chemokine receptor CXCR4 by its ligand stromal cell-derived factor 1 (SDF-1/CXCL12) may be important in the development of radiation-induced pulmonary fibrosis. Here, we tested whether MSX-122, a novel small molecule and partial CXCR4 antagonist, can block development of this fibrotic process. Methodology/Principal Findings: The radiation-induced lung fibrosis model used was C57BL/6 mice irradiated to the entire thorax or right hemithorax to 20 Gy. Our parabiotic model involved joining a transgenic C57BL/6 mouse expressing GFP with a wild-type mouse that was subsequently irradiated to assess for migration of GFP+ bone marrow-derived progenitor cells to the irradiated lung. CXCL12 levels in the bronchoalveolar lavage fluid (BALF) and serum after irradiation were determined by ELISA. CXCR4 and CXCL12 mRNA in the irradiated lung was determined by RNase protection assay. Irradiated mice were treated daily with AMD3100, an established CXCR4 antagonist; MSX-122; and their corresponding vehicles to determine impact of drug treatment on fibrosis development. Fibrosis was assessed by serial CTs and histology. After irradiation, CXCL12 levels increased in BALF and serum with a corresponding rise in CXCR4 mRNA within irradiated lungs consistent with recruitment of a CXCR4+ cell population. Using our parabiotic model, we demonstrated recruitment of CXCR4+ bone marrow-derived mesenchymal stem cells, identified based on marker expression, to irradiated lungs. Finally, irradiated mice that received MSX-122 had significant reductions in development of pulmonary fibrosis while AMD3100 did not significantly suppress this fibrotic process. Conclusions/Significance: CXCR4 inhibition by drugs such as MSX-122 may alleviate potential radiation-induced lung injury, presenting future therapeutic opportunities for patients requiring chest irradiation. © 2013 Shu et al

Stabilization of neutral stochastic delay differential equations by discrete-time feedback control

This paper is concerned with the problem of stabilization for neutral stochastic delay differential equations by feedback control based on discrete-time state observations. Firstly, sufficient conditions that ensure the mean-square exponential stability of the controlled system are established. Then the linear matrix inequalities (LMIs) approach is employed to design the discrete-time feedback controller. Finally, an illustrative example is presented to show the effectiveness of the proposed results

Correlation between Bispectral Index and Sleep Stage of Patients with Obstructive Sleep Apnea-Hypopnea Syndrome

Objective: The aim of this study was to evaluate the correlation between bispectral indexes (BIS) and sleep staging in patients with moderate to severe obstructive sleep apnea-hypopnea syndrome (OSAHS) under natural sleep conditions.&nbsp;Materials and Methods: Twelve patients who had been clinically diagnosed with OSAHS were monitored by polysomnography (PSG) and bispectral index (BIS) that were simultaneously recorded to determine the BIS at different sleep stages and analyze the patterns.&nbsp;Results: One patient did not meet the diagnostic criteria of OSAHS, and another patient lacked non-rapid eye movement stage 3 (N3) during sleep. Both patients were excluded from this study. Ten patients who met the diagnostic criteria of moderate to severe OSAHS were included in the final statistical analysis. The BIS during the following sleep stages, i.e., awake, stages N1, N2, N3, and rapid eye movement (REM) ranged from 75-91, 65-91, 60-86, 47-82, and 66-91, respectively (mean ± standard deviation: 86.3 ± 4.62, 78.4 ± 9.72, 73.8 ± 8.59, 61.8 ± 11.90, and 83.3 ± 7.32, respectively).&nbsp;Conclusion: BIS gradually decreased in the deeper stages of sleep. However, there was a considerable overlap in BIS values between different sleep stages, making it difficult to use BIS as a marker for sleep staging. To ensure an accurate examination of airways in the patient during sleep induction, these should be executed when the BIS is reduced to 77 or below.</p

G1/ELE Functions in the Development of Rice Lemmas in addition to Determining Identities of Empty Glumes

Rice empty glumes, also named sterile lemmas or rudimentary lemmas according to different interpretations, are distinct from lemmas in morphology and cellular pattern. Consistently, the molecular mechanism to control the development of lemmas is different from that of empty glumes. Rice LEAFY HULL STERILE1(OsLHS1) and DROOPING LEAF(DL) regulate the cellular pattern and the number of vascular bundles of lemmas respectively, while LONG STERILE LEMMA1 (G1)/ELONGATED EMPTY GLUME (ELE) and PANICLE PHYTOMER2 (PAP2)/OsMADS34 determine identities of empty glumes. Though some progress has been made, identities of empty glumes remain unclear, and genetic interactions between lemma genes and glume genes have been rarely elucidated. In this research, a new G1/ELE mutant g1-6 was identified and the phenotype was analyzed. Similar to previously reported mutant lines of G1/ELE, empty glumes of g1-6 plants transform into lemma-like organs. Furthermore, Phenotypes of single and double mutant plants suggest that, in addition to their previously described gene-specific functions, G1/ELE and OsLHS1 play redundant roles in controlling vascular bundle number, cell volume, and cell layer number of empty glumes and lemmas. Meanwhile, expression patterns of G1/ELE in osmads1-z flowers and OsLHS1 in g1-6 flowers indicate they do not regulate each other at the level of transcription. Finally, down-regulation of the empty glume gene OsMADS34/PAP2 and ectopic expression of the lemma gene DL, in the g1-6 plants provide further evidence that empty glumes are sterile lemmas. Generally, our findings provided valuable information for better understanding functions of G1 and OsLHS1 in flower development and identities of empty glumes

A Novel and Pleiotropic Factor SLENDER GRAIN3 Is Involved in Regulating Grain Size in Rice

Abstract:: Grain size is frequently selected during domestication and breeding. It influences the preferences of consumers, thus affecting the commercial value of rice. In present study, a mutant named as SLENDER GRAIN3 (sg3) was identified from cultivar Zhenong 41 (Oryza sativa L. ssp. indica) with ethyl methanesulfonate (EMS) treatment. Histological analysis showed that the slender grain of sg3 mutant resulted from increased cell division longitudinally and decreased cell division horizontally. Compared with the wild type Zhenong 41, starch granules in sg3 mutant were more closely packed, thus decreasing the chalkiness. Moreover, grain yield per plant in sg3 mutant was improved by 14%. By map-based cloning, SG3 was located on the long arm of chromosome 3 with a physical distance of 82 kb, and a 9-bp deletion in the 5⿲-UTR of LOC_Os03g27110 was identified, which upregulated the expression level significantly. Moreover, a molecular marker for SG3 was developed to identify the grain size during the early generation breeding in rice. The novel factor SG3 regulated the grain size mainly through changing the cell division and the endosperm formation in rice. Key words: grain size, gene mapping, phenotype analysis, ric

Numerical Simulation of the Emergency Brake Process in Granular Material Transportation Using DEM: Effect of the Liquid Bridge

AbstractA numerical simulation of the emergency brake process in granular material transportation was carried out using the Discrete Element Method (DEM). The interaction laws between the particles were based on the contact mechanics in which the normal force was calculated by the Hertz contact law and the incremental tangential force was evaluated by the Mindlin-Deresiewicz theory. Moreover, the liquid bridge force was considered in the wet particle simulation and the effect was especially discussed. Two strategies including the spatial segmentation and reconstruction of orthogonal grids were introduced to analyze the interaction force on the truck during the braking and backfilling processes. It is found that the particles concentrated in front of the truck in the brake process with a slope forming on the upper surface of the agglomerating particles. The liquid bridge force can significantly influence on the particle and force distribution trends. When the liquid bridge force was considered, the particles moved more slowly, the slope was gentler and the force on both the bottom and front wall of the truck was higher. The findings in this study reveal that the liquid bridge force plays an important role on the instantaneous distribution of the particles and pressure on the truck walls and thus cannot be ignored in the simulation

Determination of Leaf Water Content by Visible and Near-Infrared Spectrometry and Multivariate Calibration in Miscanthus

Leaf water content is one of the most common physiological parameters limiting efficiency of photosynthesis and biomass productivity in plants including Miscanthus. Therefore, it is of great significance to determine or predict the water content quickly and non-destructively. In this study, we explored the relationship between leaf water content and diffuse reflectance spectra in Miscanthus. Three multivariate calibrations including partial least squares (PLS), least squares support vector machine regression (LSSVR), and radial basis function (RBF) neural network (NN) were developed for the models of leaf water content determination. The non-linear models including RBF_LSSVR and RBF_NN showed higher accuracy than the PLS and Lin_LSSVR models. Moreover, 75 sensitive wavelengths were identified to be closely associated with the leaf water content in Miscanthus. The RBF_LSSVR and RBF_NN models for predicting leaf water content, based on 75 characteristic wavelengths, obtained the high determination coefficients of 0.9838 and 0.9899, respectively. The results indicated the non-linear models were more accurate than the linear models using both wavelength intervals. These results demonstrated that visible and near-infrared (VIS/NIR) spectroscopy combined with RBF_LSSVR or RBF_NN is a useful, non-destructive tool for determinations of the leaf water content in Miscanthus, and thus very helpful for development of drought-resistant varieties in Miscanthus