Abstract: This invention relates to a process for detecting the presence and measuring the quantity of specific mRNA sequences present in in vivo cells or cells maintained in vitro. The process of this invention is applicable to the screening of procaryotic and eucaryotic organisms including the screening of human beings for the presence of disease states. The process of this invention is also applicable to the in vitro screening of the effect or effects of chemical compounds upon one or several gene products as exhibited by the presence and amount of mRNA resulting from transcription of said gene or genes. The process of this invention is particularly suited for screening of a large number of compounds for the effect or effects of compounds upon gene products. This invention also relates to compounds capable of affecting the presence of specific mRNA sequences in cells. The process of this invention also is applicable to the identification of novel gene constructs in viruses, microorganisms, plants and animals.

Abstract: A method is provided for isolating and identifying a recombinant clone having a DNA segment therein coding for at least one desired heterologous polypeptide, at least a short amino acid sequence of which is known, by effecting cDNA synthesis on a mixture of mRNAs containing the mRNA coding of the desired polypeptide, isolating the resultant cDNA mixture, inserting the resultant cDNA into recombinant cloning vehicles, transforming hosts with the vehicles, separating the transformants and isolating and identifying a recombinant clone containing a DNA segment which is homologous over at least a portion thereof to at least one oligonucleotide probe specific for the DNA segment; wherein the probe is an extension of the nucleotide sequence of an oligonucleotide primer having a nucleotide sequence complementary to a region of the target mRNA coding for a portion of the known amino acid sequence, and is complementary to a longer region of the target mRNA coding for a longer portion of the known amino acid sequence.

Abstract: A method is provided for isolating and identifying a recombinant clone having a DNA segment therein coding for at least one desired heterologous polypeptide, at least a short amino acid sequence of which is known, by effecting cDNA synthesis on a mixture of mRNAs containing the mRNA coding for the desired polypeptide, isolating the resultant cDNA mixture, inserting the resultant cDNA into recombinant cloning vehicles, transforming hosts with the vehicles, separating the transformants and isolating and identifying a recombinant clone containing a DNA segment which is homologous over at least a portion thereof to at least one oligonucleotide probe specific for the DNA segment; wherein the probe is an extension of the nucleotide sequence of an oligonucleotide primer having a nucleotide sequence complementary to a region of the target mRNA coding for a portion of the known amino acid sequence, and is complementary to a longer region of the target mRNA coding for a longer portion of the known amino acid sequence.