Practice question

Transcript quantification by membrane hybridization predated modern microarrays. Initial formats used nylon filters dotted with large genomic clones or cDNAs at low density, a technique termed macroarray because spot diameters were large and densities were few hundred per filter. Hybridization was visualized with radioactive rather than fluorescent labeling. As technology advanced to high-density spotting of oligonucleotides on glass slides using photolithography or robotic printing, termed microarray, throughput increased dramatically. The term macroarray thus historically denotes low-density membrane predecessor, whereas polyblot, fluoroarray, and DNA beads were never standard nomenclature.