Affymetrix expression microarrays probes

Another important point was made by this study if possible, use reference samples with gene expression levels similar to those expected for the test samples. This should improve quantification at the low end. Moreover, the Tan et al., (2003) and Barczak (2003) studies also demonstrate the need for the standardization of commercial microarray products and reference standards so that both interlaboratory and cross-platform performances can be properly assessed. While commercial microarrays from different vendors all claim substantial gene probe "real estate," the number of probes in common is smaller. This makes it difficult to compare experiments across platforms, especially those from major suppliers such as Affymetrix, Agilent, and Amersham (Figure 2.8). 

FIGURE 23.1 Schematic representation of genome-scale gene expression analysis with DNA microarrays, (a) DNA microarrays produced by probe deposition (b) Oligonucleotide microarrays produced by in situ probe synthesis (Affymetrix technology). 

Figure 1. A diagram of a microarray experiment. The mRNA in a cell is fluorescently labeled and hybridized to the microarray. After the hybridization, the intensity of each probe is captured into an image that is then processed to produce a proxy of the expression level of each gene in the target. In this figure, five microarrays were used to measure the molecular profiles of three healthy cells (Samples 1-3) and two tumor cells (Samples 4 and 5). (Image courtesy of Affymetrix.)...

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