Novel design and controls for focused DNA microarrays: applications in quality assurance/control and normalization for the Health Canada ToxArray™

BMC Genomics. 2006;7(1):266 DOI 10.1186/1471-2164-7-266

 

Journal Homepage

Journal Title: BMC Genomics

ISSN: 1471-2164 (Online)

Publisher: BMC

LCC Subject Category: Technology: Chemical technology: Biotechnology | Science: Biology (General): Genetics

Country of publisher: United Kingdom

Language of fulltext: English

Full-text formats available: PDF, HTML

 

AUTHORS

Lambert Iain B
Dong Hongyan
Rowan-Carroll Andrea
Zheng Jenny L
Zhou Gu
Berndt Lynn M
Boucher Sherri
Williams Andrew
Yauk Carole L
Douglas George R
Parfett Craig L

EDITORIAL INFORMATION

Blind peer review

Editorial Board

Instructions for authors

Time From Submission to Publication: 17 weeks

 

Abstract | Full Text

<p>Abstract</p> <p>Background</p> <p>Microarray normalizations typically apply methods that assume absence of global transcript shifts, or absence of changes in internal control features such as housekeeping genes. These normalization approaches are not appropriate for focused arrays with small sets of genes where a large portion may be expected to change. Furthermore, many microarrays lack control features that can be used for quality assurance (QA). Here, we describe a novel external control series integrated with a design feature that addresses the above issues.</p> <p>Results</p> <p>An EC dilution series that involves spike-in of a single concentration of the <it>A. thaliana </it>chlorophyll synthase gene to hybridize against spotted dilutions (0.000015 to 100 μM) of a single complimentary oligonucleotide representing the gene was developed. The EC series is printed in duplicate within each subgrid of the microarray and covers the full range of signal intensities from background to saturation. The design and placement of the series allows for QA examination of frequently encountered problems in hybridization (e.g., uneven hybridizations) and printing (e.g., cross-spot contamination). Additionally, we demonstrate that the series can be integrated with a LOWESS normalization to improve the detection of differential gene expression (improved sensitivity and predictivity) over LOWESS normalization on its own.</p> <p>Conclusion</p> <p>The quality of microarray experiments and the normalization methods used affect the ability to measure accurate changes in gene expression. Novel methods are required for normalization of small focused microarrays, and for incorporating measures of performance and quality. We demonstrate that dilution of oligonucleotides on the microarray itself provides an innovative approach allowing the full dynamic range of the scanner to be covered with a single gene spike-in. The dilution series can be used in a composite normalization to improve detection of differential gene expression and to provide quality control measures.</p>