Reliability of gene expression ratios for cDNA microarrays in multiconditional experiments with a reference design

Area of Science:

• Molecular Biology
• Developmental Biology
• Genomics

Background:

• Gene expression profiling often uses a common reference sample for calculating differential expression between sample pairs.
• This indirect method relies on assembling ratios from hybridizations with the reference sample.

Purpose of the Study:

• To validate the accuracy of calculating differential gene expression indirectly using a common reference sample.
• To assess the reliability of gene expression data and identify optimal filtering techniques.
• To compare microarray results with whole-mount in situ hybridization data.

Main Methods:

• Gene expression profiling was performed on Xenopus laevis embryos across four developmental stages and a pooled sample.
• Differential expression was calculated both directly (sample i vs. j) and indirectly (sample i vs. pool * pool vs. j).
• Data quality was assessed by comparing direct and indirect values; filtering techniques were tested, including differences of repeated hybridizations.

Main Results:

• 82% of all calculated gene expression ratios were found to be sufficiently accurate when comparing direct and indirect methods.
• Filtering by differences of repeated hybridizations emerged as the optimal method for increasing signal reliability.
• Microarray-based gene expression profiles showed a 90% correspondence with whole-mount in situ hybridization patterns.

Conclusions:

• The indirect method of calculating differential gene expression using a common reference sample is largely valid for gene expression profiling.
• Optimized filtering significantly enhances the reliability of gene expression data.
• Microarray analysis provides a reliable representation of gene expression patterns, correlating well with in situ hybridization.