ABSTRACT
Subtractive hybridization is a powerful method of detecting and isolating gene sequences that are differentially expressed. Conventionally, differential hybridization has been used to detect such sequences, and procedures are described in this volume. Practically, however, it cannot be used to detect sequences with an abundance lower than approximately 0 . 1 % o f the original population (Sambrook e t al. , 1 989 : Hodge et al. , 1 992) . Many transcripts in eukaryotic cells are well below this level of abun dance and so cannot be detected this method. Suitable methods, described in this volume, include cold-plaque screening, differential display and subtractive hybridi zation.
