Biology, Medicine/Medical. a procedure for studying the activity of a specific gene, as in testing for a hereditary defect: RNA fragments in an extract of a cell population or a tissue are separated by gel electrophoresis, transferred to a filter, and then hybridized with labeled DNA or RNA derived from a laboratory-engineered copy of the gene in order to identify the size and abundance of the RNA expressed by that gene.
Origin of Northern blot
First recorded in 1977; orig. as a facetious counterpart to Southern blot