Search

A yeast (Saccharomyces cerevisiae) DNA repair reporter assay termed the GreenScreen® assay (GSA) is described. This is a novel, cost-effective genotoxicity screen, developed to provide a pre-regulatory screening assay for use by the pharmaceutical industry and in other applications where significant numbers of compounds need to be tested. It provides a higher throughput and a lower compound consumption than existing eukaryotic genotoxicity assays and is sensitive to a broad spectrum of mutagens and, importantly, clastogens. We describe a simple, robust assay protocol and a validation study. The end-point of the test reflects the typically eukaryotic chromosomes and DNA metabolizing enzymes of yeast. The capacity for metabolic activation (MA) in yeast is limited compared with the mammalian liver or its extracts, but the assay does detect a subset of compounds that would require MA in existing genotoxicity tests. The GSA detects a different spectrum of compounds to bacterial genotoxicity assays and thus, together with an in silico structure–activity relationship (SAR) screen, and possibly a high throughput bacterial screen, would provide an effective preview of the regulatory battery of genotoxicity tests.

To meet our environmental management responsibilities there is a need to estimate the likely effect of current and future soil and land management policies on water quality and choose the most effective strategies given catchment characteristics, climate and economic drivers. Efficient management of diffuse phosphorus (P) delivery from agricultural soils to streams requires mitigation strategies to be modelled such that catchment mitigation strategies can be optimised. Owing to limited catchment scale experimental results upon which a mitigation measure rule-base can be based, expert opinion was employed to make scale-dependent extrapolations from the information available. Riparian buffer zone and wetlands are selected as two examples showing how the fuzzy rules are built. We discuss the challenges in the derivation and implementation of the fuzzy rules for the mitigation measures effectiveness such as, P trapping efficiency, up-scaling process, catchment properties effect and the combination effect. The results demonstrated how effective each mitigation method could be for reducing the P delivery coefficient and that mitigation options should be selected according to catchment properties. This model can be applied for the evaluation of the effect of installed and to be installed mitigation measures on P delivery coefficient and give support for land management strategies.

Early B-cell factor (EBF) is a DNA binding protein required for early B-cell development. It activates transcription of several B-cell-specific genes, including the lambda5 gene, which encodes a protein necessary for signaling by the pre-B-cell receptor. In an effort to understand the mechanism by which EBF activates transcription, we examined its interaction with the coactivator protein p300/CBP. We found that two domains of EBF each bind the histone acetyltransferase (HAT)/CH3 domain of p300/CBP both in vitro and in vivo. Surprisingly, transcriptional activation by EBF was not sensitive to E1A, a potent p300/CBP inhibitor. In fact, overexpressed EBF mimicked E1A by severely repressing the activity of several other transcription factors, including E47, a protein that acts cooperatively with EBF to promote transcription of the lambda5 gene. This broad inhibitory profile correlated with EBFs ability to repress the HAT activity of p300/CBP in vivo and in vitro. However, such a repressed complex is not likely to form at the lambda5 promoter in vivo since (i) EBF could not bind p300/CBP and DNA simultaneously and (ii) the cooperativity imparted by E47 was sensitive to E1A. Our data reveal an intriguing inhibitory property of EBF-a property shared only by E1A, Twist, Pu.1, and the Hox family of homeodomain proteins-and suggest that E47 and EBF play distinct roles during lambda5 promoter activation., DOI does not work: 10.1128/MCB.23.11.3837.2003

not available