Histological Detection of Chicken δ-Crystallin DNA Sequences Introduced into Mouse Teratocarcinoma Cell Lines

In situ hybridization techniques to detect specific DNA sequences in histological sections were developed for the purpose of analyzing experimental chimeras produced by combination of mouse teratocarcinoma (TCC) cells stably carrying chicken δ-crystallin DNA sequences and normal mouse embryos. Various hybridization conditions for detection of exogenous DNA sequences were compared in samples of solid tumors of TCC lines. Of the conditions examined, denaturation of DNA in alkali and hybridization at 68°C in 6x SSC in the presence of dextran sulphate was the best for detecting δ-crystallin DNA sequences. With ³H-labelled probe under these conditions, virtually all nuclei containing more than 100 copies of chicken δ-crystallin sequences were labelled sufficiently to be distinguishable from nuclei without chicken sequences. This technique could be applied to other experimental chimeras in which specific DNA sequences can be used as markers of certain cell lineages.