Microarray

Microarrays, sometimes confusingly also termed microchips are the primary tools for gene expression analysis or expression profiling. A microarray is typically a glass slide onto whose surface short single-stranded DNA probes (oligomeres) are attached. Biological samples such as homogeneized cells from a tissue of interest contain messenger RNA, that will be amplified via reverse transcriptase PCR to a concentrated mixture of cDNAs that maintain the relative abundancies of the mRNAs. The cDNA is then labelled using fluorescent dyes and will hybridize with complementary strands of the immobilized microarray DNA. By using different dyes for samples from different tissues one can identify differentially expressed genes, e.g. between healthy and cancerous tissue. It is hoped that this technique helps unravel the genetic basis of many complex diseases.

Links:

• http://www.genome.gov/page.cfm?pageID=10000533 - short but substantial rundown of microarray technology
• http://industry.ebi.ac.uk/~alan/MicroArray/ - the EBI is heavily involved in standardization questions concerning microarray data
• http://www.affymetrix.com - Affymetrix currently sets the standard in microarray manufacturing