What are the main technologies used for sequencing at present?

DNA sequence analysis is the basis for further research and transformation of target genes. At present, the technologies used for sequencing mainly include chemical degradation invented by Sanger et al. (1977) and dideoxy chain termination method and Gilbert( 1977). The two methods are quite different in principle, but both of them are based on the fact that nucleotides start from a fixed point and randomly end at a specific base, resulting in a series of four groups of nucleotides with different lengths, which are then detected by electrophoresis on urea denatured PAGE gel, thus obtaining the DNA sequence. Sanger sequencing has been widely used at present.