title: Technical analysis of cDNA microarrays.
abstract: BACKGROUND
  There is extensive variation in gene expression among individuals within and between populations. Accurate measures of the variation in mRNA expression using microarrays can be confounded by technical variation, which includes variation in RNA isolation procedures, day of hybridization and methods used to amplify and dye label RNA for hybridization.
  
  
  RESULTS
  In this manuscript we analyze the relationship between the amount of mRNA and the fluorescent signal from the microarray hybridizations demonstrating that for a wide-range of mRNA concentrations the fluorescent signal is a linear function of the amount of mRNA. Additionally, the separate isolation, labeling or hybridization of RNA does not add significant amounts of variation in microarray measures of gene expression. However, single or double rounds of amplification for labeling do have small but significant affects on 10% of genes, but this source of technical variation is easy to avoid. To examine both technical and stochastic biological variation, mRNA expression was measured from the same five individuals over a six-week time course.
  
  
  CONCLUSIONS
  There were few, if any, meaningful differences in gene expression among time points. Thus, microarray measures using standard laboratory procedures can be precise and quantitative and are not subject to significant random biological noise.
authors.affiliation: Department of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, United States of America.
authors.forename: Cinda P
authors.initials: CP
authors.lastname: Scott
authors.forename: Jeff
authors.initials: J
authors.lastname: VanWye
authors.forename: M Danielle
authors.initials: MD
authors.lastname: McDonald
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Crawford
mesh_terms: D000818:Animals; D005456:Fluorescent Dyes / Q000378:metabolism; D023781:Fundulidae / Q000235:genetics; D015870:Gene Expression; D020869:Gene Expression Profiling / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D012313:RNA / Q000235:genetics / Q000378:metabolism
chemical_list: D005456:Fluorescent Dyes; D012313:RNA