Just came across this resource today, while looking up MicroArray companies. Its pretty nice and a great beginner step.
DNA microarrays can be thought of as the massively parallel version of Northern blotting. While the Northern blotting technique is capable of analysing for each experiment the expression of one single gene in different conditions, microarrays allow the exploration of the expression levels of thousands of genes in several different conditions in one single run.
As Northern blotting and many other classic techniques widely used in molecular biology, the fundamental basis of DNA microarrays is the process of hybridization. Two strands of nucleic acid, DNA or RNA, hybridize if they are complementary to each other. This principle is exploited to measure the unknown quantity of one RNA or DNA molecule (target) on the basis of the amount of a complementary sequence (probe), that has hybridized to the target. The level of hybridization is usually quantified by measuring the level of a detectable chemical label, used to mark the target or the probe sequence in the experiment.
In the microarray technique, the probe sequences are immobilized on the surface, at a separation of a few micrometers so that is possible to place many different probes on a small single surface of one square centimeter. The sample is usually labeled with a fluorescent dye that can be detected by a light scanner that scans the surface of the chip.
Each probe sequence matches a particular messenger RNA present in the sample. The concentration of a specific RNA messenger is a result of expression of its corresponding gene. Observing all the microarray spots at the same time gives the expression profile of a sample, i.e. the complete picture of the expression of all the genes represented on the microarray.
Two major technologies for the analysis of gene expression using microarrays are commonly used: oligonucleotide microarrays and spotted microarrays.
Happy experiments arrays are expensive