The Development History of Genetic Sequencer Instrument

The first generation of DNA genetic sequencer technology

In 1977, Sanger proposed the classic dideoxy nucleotide termination sequencing method. Subsequently, based on the Sanger method, in the mid-1980s, an automatic sequencer was developed that used fluorescence labeling instead of radioactive isotope labeling, and fluorescence signal receivers and computer signal analysis systems instead of radioactive self-development. In addition, capillary electrophoresis technology that appeared in the mid-1990s greatly increased the throughput of sequencing.

The traditional first-generation sequencing technology has the advantages of high accuracy, simplicity, and rapidity, but due to low sequencing throughput, it is only suitable for identifying genetic diseases in small sample candidates, and it is difficult to complete large sample case screening without clear candidate genes or a large number of candidate genes.

The second generation of DNA genetic sequencer technology

After entering the 21st century, the second generation of sequencing technology was born. Mainly, fragmented genomic DNA is connected with adapters on both sides, and then hundreds of thousands of space-fixed PCR clone arrays are produced using different methods. Then, primer hybridization and enzyme extension reactions are performed. Complete DNA sequence information is obtained through computer analysis.

Compared with the first-generation technology, the second-generation sequencing technology not only maintains high accuracy but also greatly reduces sequencing costs and significantly improves sequencing speed. The most significant feature of second-generation sequencing technology is high throughput, which can be used for tens of thousands to millions of DNA molecules to be sequenced at once, making transcriptome sequencing or genome depth sequencing for a species convenient and feasible.

The third generation of DNA genetic sequencer technology

The significant feature of third-generation sequencing technology is long reads, which can significantly increase the sequencing read length while maintaining high accuracy. The third-generation sequencing technology solves the PCR amplification process required for sequencing library preparation in the second-generation sequencing technology, to a certain extent, eliminates the systematic errors introduced by PCR, and also reduces the overall experimental run time.

The fourth generation of DNA genetic sequencer technology

The fourth-generation DNA sequencing technology also belongs to single-molecule sequencing, but its principle of using a nanopore chip to detect single-molecule sequencing signals no longer relies on high-speed cameras or high-resolution CCD cameras, which maximizes the reduction of detection equipment costs. The basic principle of most nanopore sequencing technologies is that when a DNA molecule passes through a pore, the affected electrical or light signal is detected. Due to the qualitative leap compared with the third-generation sequencing technology, it is generally called fourth-generation sequencing technology.