Dna sequencing

Abstract

A first mixture is prepared that contains labeled chain fragments which each has a common end adjacent to a primary nucleotide and a termination at a position from the primary through an nth nucleotide, the first mixture containing nucleotide chain fragments of each length from termination at the primary through termination of the nth nucleotide. A second mixture is prepared that contains labeled chain fragments beginning at the common end and terminating at positions from the first through the nth nucleotide, the second mixture containing chain fragments of each length terminating wherever either a first or a second of the four nucleotides occurs. A third mixture is prepared that contains labeled chain fragments beginning at the common end and terminating at a position from the first through the nth nucleotide, the third mixture containing chain fragments of each length terminating wherever the first or a third of the four nucleotide sequences occurs. The chains are electrophoresed with the first mixture as the center lane. This three-lane system provides a unique band pattern for each of the four nucleotides and permits the sequence to be read merely by directly comparing each of the flanking lanes with the fully stepped center lane. This system has important advantages in reducing reading errors, particularly when read with computer-assisted scanning apparatus.