Mouse genome completely decoded

The entire mouse genome has been fully decoded by scientists in the US and UK, according to a publication in the journal of Public Library of Science Biology last week.

A draught version of the genome was previously released in Nature in 2002, which was mapped using a technique called 'whole genome shotgun sequencing'. This new information is a result of the same team's effort to establish a refined version, using the more accurate techniques of clone-based sequencing and mapping. The new version closes more than 175,000 gaps in the rough version of the genome, and contains over 139 million bases of new sequence.

After the ten year effort, which cost UK and US sequencing centres around $100 million (£63m), the mouse has become only the second mammal after humans to have their whole genome mapped. Draft maps for other animals such as the rat, dog, cat, chimpanzee and macaque have been published, however.

Mice and humans share about 80 per cent of their genes, therefore scientists can find which genes in the mouse are most closely linked to the human form. There are, however, more differences between the two species than scientists originally thought; about 20 per cent of mouse genes are copies that emerged after humans became evolutionarily different.

Dr Leo Goodstadt, from the Medical Research Council Functional Genomics Unit at the University of Oxford, a co-author on the paper, said that 'in retrospect, our previous picture of the mouse genome was incomplete. Only when the missing pieces of the genomic puzzle had been filled did we realise that we had been missing large numbers of genes found only in mice, and not in humans'.

The mouse is a good model widely used for studying the evolution of animals by comparing conserved genes between species. It is also invaluable for the study of diseases; research with mice has led to advances in treatments for cancer, diabetes, heart disease and countless other conditions.

Professor Chris Ponting, also from Oxford and co-author of the study, said: 'completion of the genome is extremely important in helping us to identify the genes that underpin biology that is the same across all mammals, and to separate the genes in common from those that make humans and mice so different from one another. By filling in the gaps left by the previous version of the mouse genome, a vast treasury of new genes has been revealed. Many of these newly discovered genes are evolving at an unusually rapid pace'.