Mutual Inductance Route to Paramagnetic Meissner Effect in 2D Josephson Junction Arrays

We simulate two-dimensional Josephson junction arrays, including full mutual- inductance effects, as they are cooled below the transition temperature in a magnetic field. We show numerical simulations of the array magnetization as a function of position, as detected by a scanning SQUID which is placed at a fixed height above the array. The calculated magnetization images show striking agreement with the experimental images obtained by A. Nielsen et al. The average array magnetization is found to be paramagnetic for many values of the applied field, confirming that paramagnetism can arise from magnetic screening in multiply-connected superconductors without the presence of d-wave superconductivity.Comment: REVTeX 3.1, 5 pages, 5 figure

CyPLOS: a new family of synthetic ionophores

The ion transport properties of a new family of synthetic ionophores based on cyclic phosphate-linked oligosaccharide (CyPLOS) macrocycles are described

DNMT3B in vitro knocking-down is able to reverse embryonal rhabdomyosarcoma cell phenotype through inhibition of proliferation and induction of myogenic differentiation

Aberrant DNA methylation has been frequently observed in many human cancers, including rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children. To date, the expression and function of the de novo DNA methyltransferase (DNMT) 3B in RMS have not yet been investigated. Our study show for the first time a significant up-regulation of DNMT3B levels in 14 RMS tumour samples and 4 RMS cell lines in comparison to normal skeletal muscle. Transfection of RD and TE671 cells, two in vitro models of embryonal RMS (ERMS), with a synthetic DNMT3B siRNA decreased cell proliferation by arresting cell cycle at G1 phase, as demonstrated by the reduced expression of Cyclin B1, Cyclin D1 and Cyclin E2, and by the concomitant up-regulation of the checkpoint regulators p21 and p27. DNMT3B depletion also impaired RB phosphorylation status and decreased migratory capacity and clonogenic potential. Interestingly, DNMT3B knock-down was able to commit ERMS cells towards myogenic terminal differentiation, as confirmed by the acquisition of a myogenic-like phenotype and by the increased expression of the myogenic markers MYOD1, Myogenin and MyHC. Finally, inhibition of MEK/ERK signalling by U0126 resulted in a reduction of DNMT3B protein, giving evidence that DNMT3B is a down-stream molecule of this oncogenic pathway.Taken together, our data indicate that altered expression of DNMT3B plays a key role in ERMS development since its silencing is able to reverse cell cancer phenotype by rescuing myogenic program. Epigenetic therapy, by targeting the DNA methylation machinery, may represent a novel therapeutic strategy against RMS

Characterization of high-quality MgB2(0001) epitaxial films on Mg(0001)

High-grade MgB2(0001) films were grown on Mg(0001) by means of ultra-high-vacuum molecular beam epitaxy. Low energy electron diffraction and x-ray diffraction data indicate that thick films are formed by epitaxially oriented grains with MgB2 bulk structure. The quality of the films allowed angle-resolved photoemission and polarization dependent x-ray absorption measurements. For the first time, we report the band mapping along the Gamma-A direction and the estimation of the electron-phonon coupling constant l ~ 0.55 for the surface state electrons.Comment: 15 text pages, 6 figures Submitted for publicatio

Chemical characterization of atmospheric particulate matter in Delhi, India, part II: Source apportionment studies using PMF 3.0

World Bank reports Delhi as a second most polluted megacity in the world for particulates pollution. In Delhi, PM10 (d ≤ 10 μm) aerosol samples were monitored throughout 2008 and their characterization for major chemical elements (Na, Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Br, Sr, Ba, Pb, Cd, Sn and Sb) and ions (Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+ and Ca2+) have been documented in an earlier study. To resolve complexity in source apportionment for chemical constituents in PM10, UNMIX 6.0 and Positive Matrix Factorization (PMF 3.0) models are applied. Four factors were derived to explain routine sources of PM10 (crustal origin, road-traffic and secondary aerosols). Factor-1, designated as road-traffic source, has been determined by temporal correlation among Pb, Cu, Zn, Ni and V with strong correlation between Pb and Zn. This source factor-1 has shown more than 60% contribution to receptor site. Factor-2, referred as crustal origin due to strong inter-relationship among Si, Fe, Al, Ca and Mg, has also shown to be significant contribution to similar species in receptor matrix. Factor-3 ( NH4+, NO3-) has been differentiated due to contribution of secondary aerosols in the receptor region. This factor-3 has indicated major fraction of these ionic species for their uniform percentage variability, where mean values have been projected close to 75th percentile. Surprisingly, source factor-4 has explained the specific chloride source in the region with major contribution of 86%. For policymakers, results presented would serve as benchmark of source apportionments in Delhi

Methyltrioxorhenium catalysed synthesis of highly oxidised aryltetralin lignans with anti-topoisomerase II and apoptogenic activities

A novel and efficient procedure to prepare highly oxidised aryltetralin lignans, such as isopodophyllotoxone and (-)-aristologone derivatives, by oxidation of podophyllotoxin and galbulin with methylrhenium trioxide (MTO) and novel MTO heterogeneous catalysts is reported. It is noteworthy that in the case of isopodophyllotoxone derivatives the functionalisation of the C-4 position of the C-ring and the ring-opening of the D-lactone moiety increased the activity against topoisomerase II while causing the undesired inhibition of tubulin polymerisation to disappear. The novel (-)-aristologone derivatives showed apoptogenic activity against resistant human lymphoma cell lines.L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.co

CITRUS TRISTEZA VIRUS RESISTANCE GENE LOCUS: SMALL RNA PROFILE AND PRELIMINARY EPIGENETIC STUDIES

Small interfering RNAs (siRNAs), play a vital role in epigenetics of plant virus-host plant interactions. It has been extensively studied at both the transcriptional and post-transcriptional levels. In plants, siRNAs initiate and manage gene silencing by directing DNA methylation and/or histone methylation. In Arabidopsis, the ~24 nt siRNAs directs DNA methylation (RNA-directed DNA methylation, RdDM) and chromatin remodeling at their target loci. Recent advances in highthroughput sequencing techniques has enabled thorough exploration of small RNAs populations and allow rapid analysis of massive datasets to assemble complete full-length genome sequence for different plant species. This large database of sequence information also allows identification of genome regions specifically matched by siRNAs that likely differ among tolerant, resistant or susceptible hosts and advance epigenetic studies on diseased plants. Resistance to Citrus tristeza virus (CTV), the most severe virus affecting Citrus spp., associated with a single dominant gene locus Ctv occurring in Poncirus trifoliata while all Citrus spp. are considered susceptible. This locus contains 22 putative genes, but their regulation and mechanism for resistance remains unknown. In our study, CTV was graft-inoculated on Carrizo citrange (Poncirus trifoliata x C. sinensis (I think) ) and C. aurantium (sour orange) seedlings, and the population of siRNA characterized by high-throughput sequencing using an ILLUMINA platform. The Ctv-derived siRNA (~2% of the total short reads) were dominated in both hosts by the 24-nt. However, CTV infection caused an increase in accumulation of 24-nt siRNA sequences homologous to the Ctv gene in Carrizo but it decreased in sour orange. Distribution of the 24nt along the Ctv gene locus (282Kb) had a clearly different distribution between the two host. The predominant hot spot of siRNA in Carrizo mapped in the putative gene Ctv-20, whereas in sour orange it associated to the intergenic region between the putative genes Ctv-11 and Ctv-12, where a Copia-like retrotransposon C is located. This distribution profile was conserved for each species between CTV-infected and uninfected plants but, as previously mentioned, the frequency of the 24nt siRNAs was altered by the presence of the virus. We supposed that the different profile of 24nt between the two host in the locus ctv is due to RdDM mechanisms. To demonstrate the methylation status of the resistance locus we performed a bisulfite treatment of DNA. in which unmethylated cytosine was converted to uracile, while methylated cytosine did not react. A methylcytosines mapping was carried out on Ctv-11 and Ctv-12 sequences. By specific software were found 5 different CpG islands in the Copia-likeretrotransposon sequence and 42 primer pair were designed. The PCR analyses have been carried out using MSP and BSP primers followed by combined bisulfite restriction analysis (COBRA)

Identification of host transcriptional networks showing concentration-dependent regulation by HPV16 E6 and E7 proteins in basal cervical squamous epithelial cells.

Development of cervical squamous cell carcinoma requires increased expression of the major high-risk human-papillomavirus (HPV) oncogenes E6 and E7 in basal cervical epithelial cells. We used a systems biology approach to identify host transcriptional networks in such cells and study the concentration-dependent changes produced by HPV16-E6 and -E7 oncoproteins. We investigated sample sets derived from the W12 model of cervical neoplastic progression, for which high quality phenotype/genotype data were available. We defined a gene co-expression matrix containing a small number of highly-connected hub nodes that controlled large numbers of downstream genes (regulons), indicating the scale-free nature of host gene co-expression in W12. We identified a small number of 'master regulators' for which downstream effector genes were significantly associated with protein levels of HPV16 E6 (n = 7) or HPV16 E7 (n = 5). We validated our data by depleting E6/E7 in relevant cells and by functional analysis of selected genes in vitro. We conclude that the network of transcriptional interactions in HPV16-infected basal-type cervical epithelium is regulated in a concentration-dependent manner by E6/E7, via a limited number of central master-regulators. These effects are likely to be significant in cervical carcinogenesis, where there is competitive selection of cells with elevated expression of virus oncoproteins.Cancer Research UK (Programme Grant A13080)This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/srep2983