Mouse genome laid bare to science

By Paul Rincon
Science reporter, BBC News

It took scientists a decade to sequence the complete genome

Scientists have finished sequencing the mouse genome after a 10-year effort.

The humble mouse is the experimental workhorse in laboratories worldwide, so this high-quality genome sequence will aid in the fight against human disease.

The search for novel treatments could benefit from a greater understanding of the mouse genetic code, which is about 75% similar to our own.

An international team of researchers have published details of the work in the open-access journal PLoS Biology.

The sequence comprises the full complement of genetic material in the nucleus of a cell. It is effectively the genetic "instruction booklet" for a living animal.

The mouse (Mus musculus) becomes only the second mammal after humans to have its complete genome laid bare.

But draft sequences have been published for the chimp, dog, rat, cat, macaque and even the duck-billed platypus

The mouse is the animal most often used to better understand human illnesses and how they develop.

Research carried out using mice has led to advances in the treatment of cancer, diabetes, heart disease and countless other conditions.

Good model

Co-author Professor Chris Ponting, from the University of Oxford, told BBC News the work confirmed that the mouse was an excellent experimental model for human disease.

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"Completion of the genome is extremely important in helping us to identify the genes that underpin biology that is the same across all mammals," he said.

But he said it was also important to separate the genes humans shared with mice from those which differed between them.

About 75% of mouse genes have a single equivalent in humans. But some 5,000 genes arose after the ancestors of mice and humans went their separate evolutionary ways.

"In retrospect, our previous picture of the mouse genome was incomplete," said Dr Leo Goodstadt from the University of Oxford.

"Only when all the missing pieces of the genomic puzzle had been filled in did we realise that we had been missing large numbers of genes found only in mice, and not in humans."

The mouse genome sequencing effort began in 1999, and a draft sequence was published in 2002.

The cost, borne by US and UK sequencing centres, is estimated to exceed $100m (£62m).

Some groups oppose animal experimentation, campaigning to ban or limit the animals used.

In the UK, growth in the use of genetically modified (GM) animals - mainly mice - is largely responsible for a steady rise in the numbers of animals used in experiments since 1997.

Professor Ponting, from the Medical Research Council's (MRC) Functional Genomics Unit at Oxford, said the complete genome could provide insights into the evolution of mammals.

Humans and mice share a remarkable level of similarity, despite having evolved independently for the last 90 million years.

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