Patent ID: 7132241

Claim:
A method for selectively separating live cells which have expressed a specific mRNA from a live cell group comprising: a first step of determining a site of the specific mRNA that has high accessibility for oligonucleotide probe hybridization and preparing an oligonucleotide probe or probe set, labeled with a fluorescent dye or fluorescent dyes, having a base sequence or base sequences capable of hybridizing to the base sequence of the thus determined site, wherein the fluorescence of the fluorescent dye or fluorescent dyes will change upon the formation of a hybrid between the labeled oligonucleotide probe or probe set and the specific mRNA; a second step of introducing the labeled oligonucleotide probe or probe set into cells in a live cell group containing the live cells which have expressed the specific mRNA and the live cells which have not expressed the specific mRNA, whereby the labeled oligonucleotide probe or probe set hybridizes to the specific mRNA expressed in the live cells; a third step of irradiating light to the live cell group containing the live cells having hybridized and unhybridized oligonucleotide probe or probe set and the live cells having only unhybridized oligonucleotide probe or probe set and measuring the fluorescence which is emitted by the live cells, wherein the fluorescence from the cells having hybridized and unhybridized oligonucleotide probe or probe set is different from the fluorescence from the cells having only unhybridized oligonucleotide probe or probe set due to a change in fluorescence caused by hybrid formation, to identify the live cells wherein the hybrid formation of the labeled oligonucleotide probe or probe set and the specific mRNA has taken place; and a fourth step of separating the identified live cells from the live cell group.