Gene Expression Patterns in Dictyostelium using Microarrays

When a considerable proportion of the genes have been sequenced in a given organism, they can be densely arrayed and simultaneously hybridized with fluorescently labeled copies of mRNA. This technique can be used to compare different stages of development, responses to pharmacological treatments, or the consequences of defined mutations. In a photolithographic technique pioneered by Affymetrix, Inc. oligonucleotides are synthesized on silicon chips. However, these chips are expensive to produce and are presently restricted to studies on genes in select organisms such as yeast, humans and mice. Another technique, pioneered by Schena et al., involves robotically depositing DNA on activated glass slides. Such microarrays can be tailored to individual needs and are relatively inexpensive to produce. The individual gene sequences can be PCR amplified from either genomic DNA or cDNA clones, deposited in microtiter plates and automatically arrayed on slides. We have used this technique for studies of gene expression during development of the eukaryotic social amoeba Dictyostelium discoideum.