Elements of the maize A1 promoter required for transactivation by the anthocyanin B/C1 or phlobaphene P regulatory genes.

The extensive genetic and molecular characterization of the flavonoid pathway's structural and regulatory genes has provided some of the most detailed knowledge of gene interactions in plants. In maize flavonoid biosynthesis, the A1 gene is independently regulated in the anthocyanin and phlobaphene pathways. Anthocyanin production requires the expression of the C1 or PI and R or B regulatory genes, whereas phlobaphene production requires only the P regulatory gene. By deletion analysis of the A1 promoter, we show that the sequences between -123 and -88 are critical for activation by anthocyanin and phlobaphene regulatory genes. Linker-scanner mutations indicated that the -123 to -100 region is more important for transactivation by the P protein. The -98 to -88 region is more important for B/C1 transactivation and shows a strong homology with the region of the Bz1 anthocyanin structural gene promoter shown to be activated by B/C1 and not by P. We identified a 14-bp consensus sequence that is also present in the promoters of three other genes in the anthocyanin pathway, and we propose a model for how the flavonoid regulatory proteins interact with the promoters of the structural genes

Molecular dissection of the ozone stress responses.

The gas ozone protects against the harmful effects of ultra-violet radiation in the stratosphere. However, in the troposphere ozone is toxic to plants and causes significant reductions in crop yields. Ozone is a reactive oxygen species (ROS) and can cause oxidative damage directly by entering stomata and interacting with cell wall and membrane components. Ozone can also form other ROS such as hydrogen peroxide and hydroxyl radicals that can cross the plasma membrane and cause further damage, leading to reduced transpiration, accelerated senescence and decreased photosynthesis. In addition, the plant itself can produce ROS, which are thought to be a component of the signalling pathway. Plants react to oxidative stress by increasing their antioxidant defences in an attempt to neutralise harmful ROS. The individual roles of several antioxidants have been extensively studied, however their regulation and interaction in planta have yet to be fully elucidated. The specificity of antioxidants and other stress-related molecules to each unique stress is also poorly understood. In this work a DNA microarray has been utilised to detect novel genes in Arabidopsis thaliana, that are regulated by ozone. Twenty genes, which are significantly up-regulated and one gene that is down-regulated by ozone treatment have been identified. Five of which have been chosen for further analysis. The expression of these genes in response to a range of ozone concentrations over time has been investigated using Real Time RT-PCR. These genes have been shown to be induced specifically in response to acute ozone stress and initial studies suggest that their expression is calciumdependent

Taxing Sales under the FairTax: What Rate Works?

We are indebted to David Burton and Karen Walby for very valuable comments and to Douglas Giuffre for his As specified in Congressional bill H.R. 25/S. 25, the FairTax is a proposal to replace the federal personal income tax, corporate income tax, payroll (FICA) tax, capital gains, alternative minimum, self-employment, and estate and gifts taxes with a single-rate federal retail sales tax. The FairTax also provides a prebate to each household based on its demographic composition. The prebate is set to ensure that households pay no taxes net on spending up to the poverty level. Bill Gale (2005) and the President’s Advisory Panel on Federal Tax Reform (2005) suggest that the effective (tax inclusive) tax rate needed to implement H.R. 25 is far higher than the proposed 23 % rate. This study, which builds on Gale’s (2005) analysis, shows that a 23 % rate is eminently feasible and suggests why Gale and the Tax Panel reached the opposite conclusion. This paper begins by projecting the FairTax’s 2007 tax base net of its rebate. Next it calculates the tax rate needed to maintain the real levels of federal and state spending under the FairTax. It then determines if an effective rate of 23 % would be sufficient to fund 2007 estimated spending or if not, the amount by which non-Social Security federal expenditures would need to be reduced. Finally, it shows that the FairTa

Modification of hemicellulose content by antisense down-regulation of UDP-glucuronate decarboxylase in tobacco and its consequences for cellulose extractability

International audienc

Modification of hemicellulose content by antisense down-regulation of UDP-glucuronate decarboxylase in tobacco and its conscequence for cellulose extractability

Extractability and recovery of cellulose from cell walls influences many industrial processes and also the utilisation of biomass for energy purposes. The utility of genetic manipulation of lignin has proven potential for optimising such processes and is also advantageous for the environment. Hemicelluloses, particularly secondary wall xylans, also influence the extractability of cellulose. UDP-glucuronate decarboxylase produces UDP-xylose, the precursor for xylans and the effect of its down-regulation on cell wall structure and cellulose extractability in transgenic tobacco has been investigated. Since there are a number of potential UDP-glucuronate decarboxylase genes, a 490 bp sequence of high similarity between members of the family, was chosen for general alteration of the expression of the gene family. Sense and antisense transgenic lines were analysed for enzyme activity using a modified and optimised electrophoretic assay, for enzyme levels by western blotting and for secondary cell wall composition. Some of the down-regulated antisense plants showed high glucose to xylose ratios in xylem walls due to less xylose-containing polymers, while arabinose and uronic acid contents, which could also have been affected by any change in UDP-xylose provision, were unchanged. The overall morphology and stem lignin content of the modified lines remained little changed compared with wild-type. However, there were some changes in vascular organisation and reduction of xylans in the secondary walls was confirmed by immunocytochemistry. Pulping analysis showed a decreased pulp yield and a higher Kappa number in some lines compared with controls, indicating that they were less delignified, although the level of residual alkali was reduced. Such traits probably indicate that lignin was less available for removal in a reduced background of xylans. However, the viscosity was higher in most antisense lines, meaning that the cellulose was less broken-down during the pulping process. This is one of the first studies of a directed manipulation of hemicellulose content on cellulose extractability and shows both positive and negative outcomes