Nonradioactive detection of differentially expressed genes using complex RNA or DNA hybridization probes

The analysis of differential gene expression has become increasingly import ant in recent years. Typically, differentially expressed genes are identifi ed in a primary screening procedure, yielding candidate genes whose differe ntial expression has to be verified. We provide a highly sensitive, efficie nt and nonradioactive differential screening procedure to analyze numerous candidate genes in a single step. This comprises labeling of poly(A)(+) RNA of the cell types analyzed with DIG Chem-Link and differential hybridizati on to the candidate genes fixed on dot blots. DIG Chem-Link allows, to our knowledge, for the first time efficient and direct nonradioactive labeling of RNA in vitro. Advantages of this method include extremely short exposure times and the feasibility to re-use the probes after prolonged storage. Us ing this procedure, we isolated several genes that are differentially expre ssed in maturing Langerhans cells.