"A key limitation of genome sequencing using short reads is that the assembly usually consists of thousands of small fragments. Joining the fragments is a time-consuming, laborious process as it requires the generation of maps of markers throughout the genome. Dong et al.1 have simplified this step by taking advantage of a method known as optical mapping2. The goat genome represents the first application to a large, mammalian genome of a commercial optical mapping technology, which provides raw whole-genome mapping data in a matter of hours.
The instrument images single DNA molecules cleaved by restriction enzymes and generates maps of the distances between restriction sites. Optical mapping has been applied to assess, refine and/or assemble the genomes of many microorganisms and of rice3, maize4, mouse5 and human6by the group of David Schwartz, which pioneered the technique, but the goat genome marks a milestone with respect to commercialization of the technology.