Histo‐blotting: Hybridization in situ detection of specific RNAs on tissue sections transferred on nitrocellulose

A simple and rapid variant of in situ hybridization on tissue sections (histo‐blotting) usable for detection of specific RNA distribution among tissues is proposed. Tissue sections prepared with a cryostatic microtome are placed on nitrocellulose and these “histo‐blots” are hybridized with labelled DNA or RNA probes under conditions of Northern‐blot hybridization without any particular pretreatment. Tissue specificity of the RNA distribution may be determined by comparison of autoradiograms with the histological structure of the stained section. Histological staining and light microscopy may be carried out after hybridization of histo‐blots. Hybridization in situ may be easily combined with immunostaining under conditions of immunoblotting. Application of the proposed method is shown for alfa‐fetoprotein (AFP) and endogenous provirus (ev‐3) RNA detection in rat and chicken embryos, respectively. Histo‐blotting results correlate with the distribution of given RNAs among tissues determined by independent methods. Sensitivity, specificity and resolution of histo‐blotting have been evaluated and discussed.