Description General description 2-heptyl-3-hydroxy-4-quinolone can function as an intercellular signal. Application Quorum sensing is a signaling system used by bacteria to coordinate activity based upon their population density. The system involves the exchange of signaling molecules among bacteria via cell receptors. Heptyl-3-hydroxy-4(1H)-quinolone (PQS) is a quorum sensing-regulated virulence factor used to induce and study the regulation of virulence genes such as those involved in iron scavenging. Packaging Bottomless glass bottle. Contents are inside inserted fused cone.