DNA Sequencing and the Evolution of the “-Omics” - Insect Molecular Genetics - page 256

Figure 7.5 Diagram of the steps involved in the Maxam and Gilbert chemical cleavage method of
DNA sequencing (Modified from Hunkapiller et al. 1991.)
side by side on a sequencing gel, and the results can be visualized by autoradi-
ography ( Figure 7.5 ).
7.5 Shotgun Strategies for Genomes
In “ shotgun ” sequencing strategies, the DNA is digested with a restriction
endonuclease and subfragments are cloned and sequenced ( Figure 7.6 ). The
nucleotide sequence of the various inserts is obtained, and a computer is used
to determine how the fragments ( = contigs ) overlap and to establish the entire
sequence of the original DNA used to generate the subclones. Disadvantages
to the shotgun method are that it may underrepresent some fragments,