Large-scale sequencing identifies multiple genes and rare variants associated with Crohn’s disease susceptibility

peer reviewe

Parallel Computing Methods For The Epri Spatial Kinetics Code Arrotta

New neutronics solution methods implemented in the EPRI spatial kinetics code ARROTTA are presented. The new methods were originally developed for parallel execution, but significant performance improvement was achieved with the new methods even in serial applications. The methods are characterized by the nonlinear nodal method based on two-node coupling relations derived for both the analytic nodal method (ANM) and the nodal expansion method (NEM), a solver for the coarse mesh finite differenced problem based on a Krylov subspace method, and a domain decomposition method to achieve parallelism. The new code is examined using various transient benchmark problems which include the NEA PWR rod ejection and uncontrolled rod withdrawal at HZP. To verify the solution accuracy of the new method, comparisons are made between the original ARROTTA solutions and the new solutions for both eigenvalue and transient calculations. Comparisons are also made to assess the solution accuracy of the two-..

Increased sulfate uptake by E. coli overexpressing the SLC26-related SulP protein Rv1739c from Mycobacterium tuberculosis

Growth and virulence of mycobacteria requires sulfur uptake. The Mycobacterium tuberculosis genome contains, in addition to the ABC sulfate permease cysTWA, three SLC26-related SulP genes of unknown function. We report that induction of Rv1739c expression in E. coli increased bacterial uptake of sulfate, but not Cl−, formate, or oxalate. Uptake was time-dependent, maximal at pH 6.0, and exhibited a K1/2 for sulfate of 4.0 μM. Na+-independent sulfate uptake was not reduced by bicarbonate, nitrate, or phosphate, but was inhibited by sulfite, selenate, thiosulfate, N-ethylmaleimide and carbonyl cyanide 3-chloro-phenylhydrazone. Sulfate uptake was also increased by overexpression of the Rv1739c transmembrane domain, but not of the cytoplasmic C-terminal STAS domain. Mutation to serine of the three cysteine residues of Rv1739c did not affect magnitude, pH-dependence, or pharmacology of sulfate uptake. Expression of Rv1739c in a M. bovis BCG strain lacking the ABC sulfate permease subunit CysA could not complement sulfate auxotrophy. Moreover, inducible expression of Rv1739c in an E. coli strain lacking CysA did not increase sulfate uptake by intact cells. Our data show that facilitation of bacterial sulfate uptake by Rv1739c requires CysA and its associated sulfate permease activity, and suggest that Rv1739c may be a CysTWA-dependent sulfate transporter