Detection of gastrin-specific mRNA using oligodeoxynucleotide probes of defined sequence

Three oligodeoxynucleotides have been chemically synthesized and used as hybridization probes to detect gastrin-specific mRNA within an heterogeneous population of RNA molecules. Using these oligonucleotides whose nucleotide sequences were deduced from the amino acid sequence of the hormone, 0.2 fmol of gastrin mRNA can be detected/microgram of poly(A)-RNA from hog antrums. The 32P-labeled oligonucleotides hybridize specifically to RNA covalently coupled to DBM-paper (Alwine, J.C., Kemp, D.J., and Stark, G.R. (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 5350-5354). Labeled oligonucleotides also hybridize specifically to RNA separated by gel electrophoresis in the presence of CH3HgOH and covalently coupled to DBM-paper. Using this procedure, we have found that the mRNA coding for gastrin contains about 620 nucleotides, which is in agreement with results obtained using gastrin cDNA to determine mRNA size.