Use of sulfonated probes for in situ detection of amylase mRNA in formalin-fixed paraffin sections of human pancreas and submaxillary gland.

A sulfonated probe and its applicability to in situ hybridization is described and discussed. The DNA probes were modified by introducing an antigenic sulfone group into the cytidine residues of the denatured DNA (Budowsky EI, Sverdlov ED, Monastyrkaya GS: New method of selective and rapid modification of the cytidine residues. FEBS Lett 25:201, 1972). Hybridization of the sulfonated DNA with the target nucleic acid sequences was confirmed by an avidin-biotin peroxidase complex method using a monoclonal antibody specific to sulfonated DNA. The detection limit of this system was estimated to be about 1.25 pg of actual target sequences by dot blot hybridization analysis. When the sulfonated probes of human amylase cDNA were applied to in situ hybridization immunohistochemistry on formalin-fixed paraffin sections of the human pancreas and submaxillary gland, hybridization signals were clearly localized in the cytoplasm of the acinar cells of the pancreas, and in the serous cells of the submaxillary gland. Suitable probe lengths for in situ hybridization immunohistochemistry were between 100 and 800 bases. The in situ hybridization technique utilizing a sulfonated DNA probe is sensitive, simple, and easy to perform and applicable to studies of cell biology.