ULTRA-SENSITIVE FISH USING PEROXIDASE-MEDIATED DEPOSITION OF BIOTIN-TYRAMIDE OR FLUOROCHROME-TYRAMIDE

We describe a detection principle for indirect fluorescence in situ hy bridization (FISH) methods that with only one or two antibody layers d ramatically improves FISH signal intensities, The method uses as a fir st layer an anti-hapten immunoglobulin [or (strept)avidin] conjugated to peroxidase, The quintessence of the method is the use of fluorochro me- or biotin labelled tyramides as peroxidase substrates to generate and deposit many fluorochrome or biotin molecules close to the in situ bound peroxidase. These may either be directly evaluated under the fl uorescence microscope or after another incubation with fluorochrome-la belled (strept)avidin.