FIGURE 1.

Schematic representation of branched DNA signal amplification technologies. A pair of “Z” probes co-anneal on two 20-mer target RNA or DNA sequences (roots). The flanking regions of the Z probes are next further targeted by a subsequent probe (trunk) on which multiple sites for further fluorescent amplification are present (branches). The extreme improbability of stochastic yet close proximity annealing of two totally independent Z probes and the robust amplification provides excellent signal-to-noise ratio, allowing single-cell detection.