Figure 1.

Genes exhibiting inter-strain expression variability. (a) Genes with the most statistically significant inter-strain variance are shown using a color scale to indicate relative expression levels in the five strains. ESTs and uncharacterized transcripts are not shown. Red indicates higher expression and green indicates lower expression relative to other strains. The q-values (Q-Val) indicate the probability that each gene is falsely discovered as variable between strains. Δ fold refers to the difference in gene expression levels between the strains with the highest and lowest measurements. (b) Confirmation of transcripts with variable expression. Quantitative RT-PCR measurements of transcripts encoding apolipoprotein A-IV (ApoA4), Dnase2, aldo-keto reductase (Akr1e1), and cystathione gamma-lyase (Cth). Open bars represent results of RT-PCR quantification. Gray bars represent results of microarray quantification. (c) Confirmation of transcripts with stable expression. Quantitative RT-PCR measurements of transcripts encoding phosphofructo-kinase 2 (Pfk2), and ribosomal protein S16. S16 expression levels were used to normalize real-time PCR data, although there was not more than a 1.5-fold difference in S16 expression between any two mice. Results are expressed as fold differences relative to the lowest expressing strain for each gene (set to a value of 1). Error bars indicate the standard deviation of 12 microarray or 9 real-time PCR experiments.