Abstract: Compared with the existing methods on separating differentially expressed genes, suppression subtractive hybridization has been used extensively for the characteristics of high efficiency and low false positive rate, and reverse Northern dot blotting and expression profile gene chip of two kinds of techniques had been developed to screen the subtractive cDNA libraries. At the same time, the highly developing bioinformatics provides the most forceful means to analyse the sequence information of positive differentially expressed fragments. Furthermore, RT-PCR and real-time fluorescence quantitative PCR are the methods that further validate the differential expression of genes at mRNA level and exposit the gene functions preliminarily. After reviewing the principles, characteristics and applications of these methods, suggestion was given that the efficiency of research on differentially expressed genes will be increased largely while the cost will not if the library screening strategy was used after sequencing the clones.

Key words: library screening; differentially expressed genes; detection and assay