Non-radioactive in situ hybridization

Abstract
A number of immunocytochemical detection systems for determining the chromosomal localization of specific nucleic acid sequences by non-radioactive in situ hybridization have been compared. The procedures were: 1. the peroxidase/diaminobenzidine (PO/DAB) combination, either or not gold/silver intensificated; 2. alkaline phosphatase marking using the nitro-blue tetrazolium plus bromochloro-indolyl phosphate substrate combination (AP/NBT+CIP); and 3. immunogold with or without silver enhancement. The procedures were first tested and optimized in dot blot experiments and then applied to in situ hybridization. As hybridization probes, both a middle-repetitive and a unique sequence (modified with 2-acetyl-aminofluorene (AAF)) were used. The advantages and dis-advantages of the various methods for reflection contrast (RC) or transmission electron microscopic (TEM) visualization of hybrids are discussed.