Safer, improved sequencing in the 1980s

1980s: Automated sequencing

• Cost to sequence 1 million bases: £10,000
• Time to sequence a human genome: 600 years (!)

DNA sequencing by hand was a long and laborious process for scientists, mistakes were often made and using radioactively-labelled bases could be dangerous. So, improvements and changes had to be made, particularly if scientists were going to eventually sequence the DNA of larger organisms, such as humans! They needed a technique that was safe, easily scaled-up and efficient.

By being able to run the DNA sequencing by machine, it was easier to avoid making mistakes.

The DNA bases were now labelled with coloured dyes (A = Green, C = Blue, G = Yellow and T = Red)

Automatic sequencing machines became commercially available in the late 1980s. By being able to run the DNA sequencing by machine, it was easier to avoid making mistakes. Fragments of DNA were still separated by size but the DNA bases were now labelled with coloured dyes (A = Green, C = Blue, G = Yellow and T = Red). This meant that all four DNA bases could be loaded in the same lane. This was much easier, faster and safer than using radioactivity to label the bases of DNA.

With these automated machines, the scientists could just set up the DNA sequencer, and then leave it to run. The machine also read and recorded the order of the DNA bases, storing the information, ready to be downloaded when the scientist returned. Each base/lane had to be checked by eye because the automated systems were not always able to keep track of the lanes in the slab gel.