Tyramide Signal Amplification (TSA) Systems for the Enhancement of ISH Signals in Cytogenetics

Abstract This unit provides a series of techniques that dramatically improve the sensitivity of direct and indirect in situ detection. TSA is a peroxidase‐based signal amplification system which is compatible with all in situ hybridization as well as immunocytochemical detection systems. The assay is performed on a glass slide and combines the use of fluorescent probes in either direct or indirect format using either an enzyme‐labeled streptavidin or antibody. Protocols are provided for brightfield and fluorescent detection of single DNA targets, DNA or RNA in cultured cells, multitarget detection for DNA/RNA and DNA and RNA. In addition a protocol is included for the TSA plus system, a DNP‐based detection system using horseradish peroxidase and alkaline phosphatase.