Profiles of Global Gene Expression in Ionizing-Radiation–Damaged Human Diploid Fibroblasts Reveal Synchronization behind the G(1) Checkpoint in a G(0)-like State of Quiescence

Cell cycle arrest and stereotypic transcriptional responses to DNA damage induced by ionizing radiation (IR) were quantified in telomerase-expressing human diploid fibroblasts. Analysis of cytotoxicity demonstrated that 1.5 Gy IR inactivated colony formation by 40–45% in three fibroblast lines; this dose was used in all subsequent analyses. Fibroblasts exhibited > 90% arrest of progression from G(2) to M at 2 hr post-IR and a similarly severe arrest of progression from G(1) to S at 6 and 12 hr post-IR. Normal rates of DNA synthesis and mitosis 6 and 12 hr post-IR caused the S and M compartments to empty by > 70% at 24 hr. Global gene expression was analyzed in IR-treated cells. A microarray analysis algorithm, EPIG, identified nine IR-responsive patterns of gene expression that were common to the three fibroblast lines, including a dominant p53-dependent G(1) checkpoint response. Many p53 target genes, such as CDKN1A, GADD45, BTG2, and PLK3, were significantly up-regulated at 2 hr post-IR. Many genes whose expression is regulated by E2F family transcription factors, including CDK2, CCNE1, CDC6, CDC2, MCM2, were significantly down-regulated at 24 hr post-IR. Numerous genes that participate in DNA metabolism were also markedly repressed in arrested fibroblasts apparently as a result of cell synchronization behind the G(1) checkpoint. However, cluster and principal component analyses of gene expression revealed a profile 24 hr post-IR with similarity to that of G(0) growth quiescence. The results reveal a highly stereotypic pattern of response to IR in human diploid fibroblasts that reflects primarily synchronization behind the G(1) checkpoint but with prominent induction of additional markers of G(0) quiescence such as GAS1

The Role of Marketing at Duke Power Company

This paper examines the changes that have taken place in Duke Power's marketing philosophy, particularly in the industrial marketing sector. The emphasis has shifted from load management to strategic sales for boosting the use of off-peak power. Duke Power is implementing a number of programs and services that not only promote new ways to use electricity in industrial processes, but also promote economic development in its 20,000 square mile service area. These programs highlighted in this paper are as follows: • Heat Recovery Systems • Economic Development • Industrial Customer Focus Program • Power System Disturbance Policy • Industrial Energy Audits • Rate

The MicroArray Quality Control (MAQC)-II study of common practices for the development and validation of microarray-based predictive models

Gene expression data from microarrays are being applied to predict preclinical and clinical endpoints, but the reliability of these predictions has not been established In the MAQC II project, 36 independent teams analyzed six microarray data sets to generate predictive models for classifying a sample with respect to one of 13 endpoints indicative of lung or liver toxicity in rodents, or of breast cancer, multiple myeloma or neuroblastoma in humans In total, &gt;30,000 models were built using many combinations of analytical methods The teams generated predictive models without knowing the biological meaning of some of the endpoints and, to mimic clinical reality, tested the models on data that had not been used for training We found that model performance depended largely on the endpoint and team proficiency and that different approaches generated models of similar performance The conclusions and recommendations from MAQC-II should be useful for regulatory agencies, study committees and independent investigators that evaluate methods for global gene expression analysis</span

Specific interference with gene function by double-stranded RNA in early mouse development

The use of double-stranded (ds) RNA is a powerful way of interfering with gene expression in a range of organisms, but doubts have been raised about whether it could be successful in mammals. Here, we show that dsRNA is effective as a specific inhibitor of the function of three genes in the mouse, namely maternally expressed c-mos in the oocyte and zygotically expressed E-cadherin or a GFP transgene in the preimplantation embryo. The phenotypes observed are the same as those reported for null mutants of the endogenous genes. These findings offer the opportunity to study development and gene regulation in normal and diseased cells