A Mutation in Amino Acid Permease AAP6 Reduces the Amino Acid Content of the Arabidopsis Sieve Elements but Leaves Aphid Herbivores Unaffected.

The aim of this study was to investigate the role of the amino acid permease gene AAP6 in regulating phloem amino acid composition and then to determine the effects of this altered diet on aphid performance. A genotype of Arabidopsis thaliana (L.) was produced in which the function of the amino acid permease gene AAP6 (At5g49630) was abolished. Plants homozygous for the insertionally inactivated AAP6 gene had a significantly larger mean rosette width than the wild type and a greater number of cauline leaves. Seeds from the aap6 mutant were also significantly larger than those from the wild-type plants. Sieve element (SE) sap was collected by aphid stylectomy and the amino acids derivatized, separated, and quantified using Capillary Electrophoresis with Laser Induced Fluorescence (CE-LIF). In spite of the large variation across samples, the total amino acid concentration of SE sap of the aap6 mutant plants was significantly lower than that of the wild-type plants. The concentrations of lysine, phenylalanine, leucine, and aspartic acid were all significantly lower in concentration in the aap6 mutant plants compared with wild-type plants. This is the first direct demonstration of a physiological role for an amino acid transporter in regulating SE composition in vivo. The amino acid availability in sieve element sap is thought to be the major limiting factor for aphid growth and reproduction. Despite the changes in their diet, the aphid Myzus persicae(Sulzer) displayed only small changes in feeding behaviour on mutant plants when measured using the Electronic Penetration Graph (EPG) technique. Salivation by the aphid into the SE (E1 phase) was increased on mutant plants but there was no significant effect on other feeding EPG behaviours, or in the rate of honeydew production. Consistent with the small effect on aphid feeding behaviour, there was only a small effect of reduced sieve element amino acid concentration on aphid reproduction. The data are discussed in relation to the regulation of phloem composition and the role of phloem amino acids in regulating aphid performance

Improved Quenched QCD on Large Lattices - First Results

Continuing our investigations of quenched QCD with improved fermions we have started simulations for lattice size 32^3 x 64 at beta=6.2. We present first results for light hadron masses at kappa=0.13520, 0.13540, and 0.13555. Moreover we compare our initial experiences on the T3E with those for APE/Quadrics systems.Comment: 3 pages, Latex2e, 4 figures, espcrc2, epsfig and latexsym require

An alignment algorithm for bisulfite sequencing using the Applied Biosystems SOLiD System

Summary: Bisulfite sequencing allows cytosine methylation, an important epigenetic marker, to be detected via nucleotide substitutions. Since the Applied Biosystems SOLiD System uses a unique di-base encoding that increases confidence in the detection of nucleotide substitutions, it is a potentially advantageous platform for this application. However, the di-base encoding also makes reads with many nucleotide substitutions difficult to align to a reference sequence with existing tools, preventing the platform's potential utility for bisulfite sequencing from being realized. Here, we present SOCS-B, a reference-based, un-gapped alignment algorithm for the SOLiD System that is tolerant of both bisulfite-induced nucleotide substitutions and a parametric number of sequencing errors, facilitating bisulfite sequencing on this platform. An implementation of the algorithm has been integrated with the previously reported SOCS alignment tool, and was used to align CpG methylation-enriched Arabidopsis thaliana bisulfite sequence data, exhibiting a 2-fold increase in sensitivity compared to existing methods for aligning SOLiD bisulfite data

Coronary Artery Surgery Study (CASS): Comparability of 10 year survival in randomized and randomizable patients

AbstractThe Coronary Artery Surgery Study (CASS) includes 780 patients with mild or moderate stable angina pectoris or asymptomatic survivors of a myocardial infarction who were randomized to either medical or surgical therapy and 1,319 patients who were eligible for randomization but were not randomized (randomizable patients). There were no substantial aggregate differences observed in any of the survival comparisons after 10 years of follow-up study between the randomized and randomizable patients assigned to the medical (79% versus 80%) or surgical (82% versus 81%) groups or in patient subgroups stratified according to coronary artery disease extent and left ventricular ejection fraction.Cox regression analyses were done with independent variables known to be predictors of survival, including surgical versus medical therapy and randomized versus randomizable group, to test the null hypothesis of a mortality difference between medical versus surgical assignment according to group assignment (randomized versus randomizable). In no case did the initial group category enter as a significant predictor of survival. The results in the randomizable group reinforce those in the randomized group with respect to the medical versus surgical comparison.Two subgroups are identified with a significant surgical advantage: 1) patients with proximal left anterior descending coronary artery stenosis ≥70% and an ejection fraction < 0.50, and 2) patients with three vessel coronary artery disease and an ejection fraction < 0.50. In both groups, coronary bypass surgery had a statistically significant beneficial effect on survival (p < 0.05).After a decade of follow-up, the CASS randomizable patients confirm conclusions reached on the basis of the CASS randomized trial

Non-perturbatively renormalised light quark masses from a lattice simulation with N_f=2

We present results for the light quark masses obtained from a lattice QCD simulation with N_f=2 degenerate Wilson dynamical quark flavours. The sea quark masses of our lattice, of spacing a ~ 0.06 fm, are relatively heavy, i.e., they cover the range corresponding to 0.60 <~ M_P/M_V <~ 0.75. After implementing the non-perturbative RI-MOM method to renormalise quark masses, we obtain m_{ud}^{MS}(2 GeV)=4.3 +- 0.4^{+1.1}_{-0} MeV, and m_s^{MS}(2 GeV)=101 +- 8^{+25}_{-0} MeV, which are about 15% larger than they would be if renormalised perturbatively. In addition, we show that the above results are compatible with those obtained in a quenched simulation with a similar lattice.Comment: 18 pages, 5 figure