Adaptation in Time and to Stimuli

Pathogens survive in a harsh environment. There is a constant race between host defense and parasite escape. In addition, their life cycle involves often abrupt changes of habitat (e.g. bloodborne, airborne, waterborne, intracellular, in a macrophage, in the gut). Quick adaptation is critical, and rapid changes can be monitored using gene expression analysis. Microarray analysis has now become the method of choice for rapid capture of genome-wide adaptation (including changes within minutes). The essentials are summarized below. In this technology the probe, consisting of oligonucleotides, either cDNA or DNA sequences are spotted on a glass support, or oligonucleotides are synthesized directly on the array using photolithographic masks. RNA samples are fluorescently labeled and hybridized to the arrayed probes. The signal intensities of the hybridized spots are used to estimate relative RNA concentration. Subsequent longer time scales are then reflected in the proteome.

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