Mapping of ionomic traits in Mimulus guttatus reveals Mo and Cd QTLs that colocalize with MOT1 homologues

Peer reviewedPublisher PD

Monoamine oxidase-A modulates apoptotic cell death induced by staurosporine in human neuroblastoma cells

Monoamine oxidases (MAOs) are mitochondrial enzymes which control the levels of neurotransmitters in the brain and dietary amines in peripheral tissues via oxidative deamination. MAO has also been implicated in cell signalling. In this study, we describe the MAO-A isoform as functional in apoptosis induced by staurosporine (STS) in human dopaminergic neuroblastoma cells (SH-SY5Y). Increased levels of MAO-A activity were induced by STS, accompanied by increased MAO-A protein and activation of the initiator of the intrinsic pathway, caspase 9, and the executioner caspase 3. MAO-A mRNA levels were unaffected by STS, suggesting that changes in MAO-A protein are due to post-transcriptional events. Two unrelated MAO-A inhibitors reduced caspase activation. STS treatment resulted in sustained activation of the mitogen-activated protein kinase pathway enzymes extracellular regulated kinase, c-jun terminal kinase and p38, and depletion of the anti-apoptotic protein Bcl-2. These changes were significantly reversed by MAO inhibition. Production of reactive oxygen species was increased following STS exposure, which was blocked by both MAO inhibition and the antioxidant N-acetylcysteine. Therefore our data provide evidence that MAO-A, through its production of reactive oxygen species as a by-product of its catalytic activity on the mitochondrial surface, is recruited by the cell to enhance apoptotic signalling

Natural variation in abiotic stress responsive gene expression and local adaptation to climate in Arabidopsis thaliana.

Gene expression varies widely in natural populations, yet the proximate and ultimate causes of this variation are poorly known. Understanding how variation in gene expression affects abiotic stress tolerance, fitness, and adaptation is central to the field of evolutionary genetics. We tested the hypothesis that genes with natural genetic variation in their expression responses to abiotic stress are likely to be involved in local adaptation to climate in Arabidopsis thaliana. Specifically, we compared genes with consistent expression responses to environmental stress (expression stress responsive, "eSR") to genes with genetically variable responses to abiotic stress (expression genotype-by-environment interaction, "eGEI"). We found that on average genes that exhibited eGEI in response to drought or cold had greater polymorphism in promoter regions and stronger associations with climate than those of eSR genes or genomic controls. We also found that transcription factor binding sites known to respond to environmental stressors, especially abscisic acid responsive elements, showed significantly higher polymorphism in drought eGEI genes in comparison to eSR genes. By contrast, eSR genes tended to exhibit relatively greater pairwise haplotype sharing, lower promoter diversity, and fewer nonsynonymous polymorphisms, suggesting purifying selection or selective sweeps. Our results indicate that cis-regulatory evolution and genetic variation in stress responsive gene expression may be important mechanisms of local adaptation to climatic selective gradients

Operating characteristics of a D.C. magnetic ion source

The operating characteristics of an ion source of the type described by Kistemaker and Dekker are given. The dependence of the total ion output on the ion source pressure, magnetic field, anode voltage, filament emission, and probe voltage is described. When hydrogen gas was used the ion· source operated stably for pressures in the range of 1.5 to 2.5 microns of Hg producing maximum ion currents of 3 to 5 ma. Its gas consumption was relatively high (22.5 cc/hr, STP) and the proton percentage of the ion beam was of the order of 8%. The best focusing gave a beam diameter of 5 mm on a target 2 meters from the ion source. The filament lifetimes varied from 50 to more than 100 hours. The power consumption for ion beams of 3 ma or less was found to be about 0.15 watts/ua

Neuraminidase Activity in \u3cem\u3eDiplococcus pneumoniae\u3c/em\u3e

Kelly, R. T. (Marquette University School of Medicine, Milwaukee, Wis.), D. Greiff, and S. Farmer. Neuraminidase activity in Diplococcus pneumoniae. J. Bacteriol. 91:601–603. 1966.—A method for the quantitation of neuraminidase in the presence of N-acetylneuraminic acid aldolase is described. The neuraminidase content of Diplococcus pneumoniae was found to be dependent on the media employed for growth; the highest enzyme activity per milligram of bacterial protein was obtained with Todd-Hewitt broth. Neuraminidase production was stimulated in D. pneumoniae by the addition of N-acetylneuraminlactose, N-acetylneuraminic acid, or N-acetylmannosamine to the growth medium. Three rough strains of D. pneumoniae, which were nonpathogenic for mice, lacked neuraminidase activity. Seven of 12 smooth strains contained neuraminidase; enzyme activity was not detected in the remaining 5 smooth strains. There was no correlation between the presence of neuraminidase activity and the capsular type or between neuraminidase production and animal virulence

Molecular Analyses of Human Induced Pluripotent Stem Cells and Embryonic Stem Cells

SummaryRecent work from our group and others has argued that human induced pluripotent stem cells (hiPSCs) generated by the introduction of four viruses bearing reprogramming factors differ from human embryonic stem cells (hESCs) at the level of gene expression (Chin et al., 2009). Many of the differences seen were common across independent labs and, at least to some extent, are thought to be a result of residual expression of donor cell-specific genes (Chin et al., 2009; Ghosh et al., 2010; Marchetto et al., 2009). Two new reports reanalyze similar expression data sets as those used in Chin et al. (2009) and come to different conclusions (Newman and Cooper, 2010; Guenther et al., 2010). We compare various approaches to perform gene expression meta-analysis that all support our original conclusions and present new data to demonstrate that polycistronic delivery of the reprogramming factors and extended culture brings hiPSCs transcriptionally closer to hESCs

Effects of Monovalent and Divalent Cations on Ca2+ Fluxes Across Chromaffin Secretory Membrane Vesicles

Abstract: Bovine chromaffin secretory vesicle ghosts loaded with Na+ were found to take up Ca2+ when incubated in K+ media or in sucrose media containing micromolar concentrations of free Ca2+. Li+- or choline+loaded ghosts did not take up Ca2+. The Ca2+ accumulated by Na+-loaded ghosts could be released by the Ca2+ ionophore A23187, but not by EGTA. Ca2+ uptake was inhibited by external Sr2+, Na +, Li +, or choline +. All the 45Ca2+ accumulated by Na+-dependent Ca2+ uptake could be released by external Na +, indicating that both Ca2+ influx and efflux occur in a Na+-dependent manner. Na + -dependent Ca2+ uptake and release were only slightly inhibited by Mg2+. In the presence of the Na+ ionophore Monensin the Ca2+ uptake by Na +-loaded ghosts was reduced. Ca2+ sequestered by the Na+-dependent mechanism could also be released by external Ca2+ or Sr2+ but not by Mg2+, indicating the presence of a Ca2+/Ca2+ exchange activity in secretory membrane vesicles. This Ca2+/Ca2+ exchange system is inhibited by Mg2+, but not by Sr2+. The Na + -dependent Ca2+ uptake system in the presence of Mg2+ is a saturable process with an apparent Km of 0.28 μM and a Vmax= 14.5 nmol min−1 mg protein−1. Ruthenium red inhibited neither the Na+/Ca2+ nor the Ca2+/Ca2+ exchange, even at high concentrations

Sensing and control in dual-recycling laser interferometer gravitational-wave detectors

We introduce length-sensing and control schemes for the dual-recycled cavity-enhanced Michelson interferometer configuration proposed for the Advanced Laser Interferometer Gravitational Wave Observatory (LIGO). We discuss the principles of this scheme and show methods that allow sensing and control signals to be derived. Experimental verification was carried out in three benchtop experiments that are introduced. We present the implications of the results from these experiments for Advanced LIGO and other future interferometric gravitational-wave detectors

QTL and Drought Effects on Leaf Physiology in Lowland Panicum virgatum

Switchgrass is a key component of plans to develop sustainable cellulosic ethanol production for bioenergy in the USA. We sought quantitative trait loci (QTL) for leaf structure and function, using the Albany full-sib mapping population, an F1 derived from lowland tetraploid parents. We also assessed both genotype × environment interactions (G×E) in response to drought and spatial trends within experimental plots, using the mapping population and check clones drawn from the parent cultivars. Phenotypes for leaf structure and physiological performance were determined under well-watered conditions in two consecutive years, and we applied drought to one of two replicates to test for G×E. Phenotypes for check clones varied with location in our plot and were impacted by drought, but there was limited evidence of G×E except in quantum yield (ΦPSII). Phenotypes of Albany were also influenced by plant location within our plot, and after correcting for experimental design factors and spatial effects, we detected QTL for leaf size, tissue density (LMA), and stomatal conductance (gs). Clear evidence of G×E was detected at a QTL for intrinsic water use efficiency (iWUE) that was expressed only under drought. Loci influencing physiological traits had small additive effects, showed complex patterns of heritability, and did not co-localize with QTL for morphological traits. These insights into the genetic architecture of leaf structure and function set the stage for consideration of leaf physiological phenotypes as a component of switchgrass improvement for bioenergy purposes