Certification of a reference material of Campylobacter coli and jejuni (CNET068 and CNET112) agarose plugs for PFGE: IRMM-313

This report describes the production of IRMM-313, a Campylobacter coli and jenuni gDNA material certified for the size of the DNA fragments obtained by enzymatic restriction and Pulsed Field Gel Electrophoresis (PFGE). The material was produced following ISO Guide 34:2009. The CRM was produced from cultures of Campylobacter coli CNET068 and jejuni CNET112 which were pooled and processed into agarose plugs suited for PFGE. The bacterial cells were lysed as to release the gDNA within the plug. Between unit-homogeneity and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. The material was characterised by an intercomparison among laboratories of demonstrated competence and complying to ISO/IEC 17025. Technically invalid results were removed but no outlier was eliminated on statistical grounds only. The certified values were obtained by PFGE. Uncertainties of the certified values were calculated in compliance with the Guide to the Expression of Uncertainty in Measurement (GUM). The material is intended for quality control and assessment of method performance. As any reference material, it can also be used for control charts or validation studies. The CRM is available in plastic screw cap vials containing 1 plug suspended in Tris EDTA buffer solution. The minimum amount of sample recommended to be used is ½ plug.JRC.D.2-Standards for Innovation and sustainable Developmen

Spin liquid correlations in Nd-langasite anisotropic Kagom\'e antiferromagnet

Dynamical magnetic correlations in the geometrically frustrated Nd$\_3$Ga$\_5$SiO$\_{14}$ compound were probed by inelastic neutron scattering on a single crystal. A scattering signal with a ring shape distribution in reciprocal space and unprecedented dispersive features was discovered. Comparison with calculated static magnetic scattering from models of correlated spins suggests that the observed phase is a spin liquid inherent to an antiferromagnetic kagom\'e-like lattice of anisotropic Nd moments.Comment: 4 page

Inhomogeneous magnetism in the doped kagome lattice of LaCuO2.66

The hole-doped kagome lattice of Cu2+ ions in LaCuO2.66 was investigated by nuclear quadrupole resonance (NQR), electron spin resonance (ESR), electrical resistivity, bulk magnetization and specific heat measurements. For temperatures above ~180 K, the spin and charge properties show an activated behavior suggestive of a narrow-gap semiconductor. At lower temperatures, the results indicate an insulating ground state which may or may not be charge ordered. While the frustrated spins in remaining patches of the original kagome lattice might not be directly detected here, the observation of coexisting non-magnetic sites, free spins and frozen moments reveals an intrinsically inhomogeneous magnetism. Numerical simulations of a 1/3-diluted kagome lattice rationalize this magnetic state in terms of a heterogeneous distribution of cluster sizes and morphologies near the site-percolation threshold

Nonmagnetic insulator state in Na1CoO2 and phase separation of Na vacancies

Crystallographic, magnetic, and NMR properties of a NaxCoO2 single crystal with x≃1 are presented. We identify the stoichiometric Na1CoO2 phase, which is shown to be a nonmagnetic insulator, as expected for homogeneous planes of Co3+ ions with S=0. In addition, we present evidence that, because of slight average Na deficiency, chemical and electronic phase separation leads to a segregation of Na vacancies into the well-defined, magnetic, Na0.8CoO2 phase. The importance of phase separation is discussed in the context of magnetic order for x≃0.8 and the occurrence of a metal-insulator transition for x→1

Vibronic collapse of ordered quadrupolar ice in the pyrochore magnet Tb2+x_{2+x}Ti2−x_{2-x}O7+y_{7+y}

While the spin liquid state in the frustrated pyrochlore Tb$_{2+x}$Ti$_{2-x}$O$_{7+y}$ has been studied both experimentally and theoretically for more than two decades, no definite description of this unconventional state has been achieved. Using synchrotron based THz spectroscopy in combination with quantum numerical simulations, we highlight a significant link between two previously unrelated features: the existence of a quadrupolar order following an ice rule and the presence of strong magneto-elastic coupling in the form of hybridized Tb$^{3+}$ crystal-field and phonon modes. The magnitude of this so-called vibronic process, which involves quadrupolar degrees of freedom, is significantly dependent on small off-stoichiometry $x$ and favors all-in all-out like correlations between quadrupoles. This mechanism competes with the long range ordered quadrupolar ice, and for slightly different stoichiometry, is able to destabilize it.Comment: Main text: 7 pages, 3 figures ; Supplemental Material: 6 pages, 2 figure

The C. elegans H3K27 Demethylase UTX-1 Is Essential for Normal Development, Independent of Its Enzymatic Activity

Epigenetic modifications influence gene expression and provide a unique mechanism for fine-tuning cellular differentiation and development in multicellular organisms. Here we report on the biological functions of UTX-1, the Caenorhabditis elegans homologue of mammalian UTX, a histone demethylase specific for H3K27me2/3. We demonstrate that utx-1 is an essential gene that is required for correct embryonic and postembryonic development. Consistent with its homology to UTX, UTX-1 regulates global levels of H3K27me2/3 in C. elegans. Surprisingly, we found that the catalytic activity is not required for the developmental function of this protein. Biochemical analysis identified UTX-1 as a component of a complex that includes SET-16(MLL), and genetic analysis indicates that the defects associated with loss of UTX-1 are likely mediated by compromised SET-16/UTX-1 complex activity. Taken together, these results demonstrate that UTX-1 is required for many aspects of nematode development; but, unexpectedly, this function is independent of its enzymatic activity

Genome-wide association analyses identify new Brugada syndrome risk loci and highlight a new mechanism of sodium channel regulation in disease susceptibility

Brugada syndrome (BrS) is a cardiac arrhythmia disorder associated with sudden death in young adults. With the exception of SCN5A, encoding the cardiac sodium channel NaV1.5, susceptibility genes remain largely unknown. Here we performed a genome-wide association meta-analysis comprising 2,820 unrelated cases with BrS and 10,001 controls, and identified 21 association signals at 12 loci (10 new). Single nucleotide polymorphism (SNP)-heritability estimates indicate a strong polygenic influence. Polygenic risk score analyses based on the 21 susceptibility variants demonstrate varying cumulative contribution of common risk alleles among different patient subgroups, as well as genetic associations with cardiac electrical traits and disorders in the general population. The predominance of cardiac transcription factor loci indicates that transcriptional regulation is a key feature of BrS pathogenesis. Furthermore, functional studies conducted on MAPRE2, encoding the microtubule plus-end binding protein EB2, point to microtubule-related trafficking effects on NaV1.5 expression as a new underlying molecular mechanism. Taken together, these findings broaden our understanding of the genetic architecture of BrS and provide new insights into its molecular underpinnings

Genome-wide association analyses identify new Brugada syndrome risk loci and highlight a new mechanism of sodium channel regulation in disease susceptibility.

Brugada syndrome (BrS) is a cardiac arrhythmia disorder associated with sudden death in young adults. With the exception of SCN5A, encoding the cardiac sodium channel Na1.5, susceptibility genes remain largely unknown. Here we performed a genome-wide association meta-analysis comprising 2,820 unrelated cases with BrS and 10,001 controls, and identified 21 association signals at 12 loci (10 new). Single nucleotide polymorphism (SNP)-heritability estimates indicate a strong polygenic influence. Polygenic risk score analyses based on the 21 susceptibility variants demonstrate varying cumulative contribution of common risk alleles among different patient subgroups, as well as genetic associations with cardiac electrical traits and disorders in the general population. The predominance of cardiac transcription factor loci indicates that transcriptional regulation is a key feature of BrS pathogenesis. Furthermore, functional studies conducted on MAPRE2, encoding the microtubule plus-end binding protein EB2, point to microtubule-related trafficking effects on Na1.5 expression as a new underlying molecular mechanism. Taken together, these findings broaden our understanding of the genetic architecture of BrS and provide new insights into its molecular underpinnings

Inactivation of Poliovirus 1 and F-Specific RNA Phages and Degradation of Their Genomes by UV Irradiation at 254 Nanometers

Several models (animal caliciviruses, poliovirus 1 [PV1], and F-specific RNA bacteriophages) are usually used to predict inactivation of nonculturable viruses. For the same UV fluence, viral inactivation observed in the literature varies from 0 to 5 logs according to the models and the methods (infectivity versus molecular biology). The lack of knowledge concerning the mechanisms of inactivation due to UV prevents us from selecting the best model. In this context, determining if viral genome degradation may explain the loss of infectivity under UV radiation becomes essential. Thus, four virus models (PV1 and three F-specific RNA phages: MS2, GA, and Qβ) were exposed to UV radiation from 0 to 150 mJ · cm(−2). PV1 is the least-resistant virus, while MS2 and GA phages are the most resistant, with phage Qβ having an intermediate sensitivity; respectively, 6-log, 2.3-log, 2.5-log, and 4-log decreases for 50 mJ · cm(−2). In parallel, analysis of RNA degradation demonstrated that this phenomenon depends on the fragment size for PV1 as well as for MS2. Long fragments (above 2,000 bases) for PV1 and MS2 fell rapidly to the background level (>1.3-log decrease) for 20 mJ · cm(−2) and 60 mJ · cm(− 2), respectively. Nevertheless, the size of the viral RNA is not the only factor affecting UV-induced RNA degradation, since viral RNA was more rapidly degraded in PV1 than in the MS2 phage with a similar size. Finally, extrapolation of inactivation and UV-induced RNA degradation kinetics highlights that genome degradation could fully explain UV-induced viral inactivation

The Certification of Different Mass Fractions of DAS-68416-4 in Soya Seed Powder: ERM®-BF432a, ERM®-BF432b, ERM®-BF432c and ERM®-BF432d

This report describes the production of a set of Certified Reference Materials (CRMs) ERM-BF432a, b, c and d, matrix materials certified for their DAS-68416-4 mass fractions. The material has been produced following ISO Guide 34:2009 [1].Genetically modified (GM) seeds of the soya event DAS-68416-4 and of a non-GM soya variety were ground to obtain GM and non-GM base powders. A non-GM pure material was prepared and gravimetric mixtures of non-GM and GM soya powder were prepared by dry-mixing. Between unit-heterogeneity has been quantified and stability during dispatch and storage have been assessed in accordance with ISO Guide 35:2006 [2].The certified value was obtained from the gravimetric preparations, taking into account the purity of the base materials and their water mass fraction. The certified values were confirmed by event-specific real-time PCR as independent verification method (measurements within the scope of accreditation to ISO/IEC 17025).Uncertainties of the certified values were calculated in compliance with the Guide to the Expression of Uncertainty in Measurement (GUM) [3] and include uncertainties related to possible heterogeneity and instability and to characterisation. The materials are intended for the calibration or quality control of methods. As any reference material, they can also be used for control charts or validation studies. The CRMs are available in glass vials containing 1 g of dried soya seed powder closed under argon atmosphere. The minimum amount of sample to be used is 500 mg.The CRM has been accepted as European Reference Material (ERM®) after peer evaluation by the partners of the European Reference Materials consortium.JRC.D.2-Standards for Innovation and sustainable Developmen