Mussels that can mend their own genes offer chance of new cancer treatments

A deep-sea mussel that can mend its own genes is helping scientists to devise new treatments for cancer and diseases caused by damage to DNA.

A deep-sea mussel that can mend its own genes is helping scientists to devise new treatments for cancer and diseases caused by damage to DNA.

The mussel was found living near underwater volcanoes in the mid-Atlantic, where hydrothermal vents spew toxic emissions at temperatures of about 400C.

David Dixon, a scientist on the British Mid-Ocean Ridge Initiative (Bridge) - funded by the Natural Environment Research Council- said that enzymes extracted from the mussel could help to repair damage to human DNA.

The mussels can survive with up to 50 per cent of their DNA damaged and are able to reduce this damage to about 5 per cent when placed in non-toxic conditions, said Dr Dixon, based at the Southampton Oceanographic Centre.

Ordinary mussels usually live with only about 2 per cent of their DNA being damaged and die when more than 20 per cent remains unrepaired, he said.

"The deep-sea mussels seem to be able to survive with an overall higher background DNA damage. One can imagine, in say cancer treatment, that one could harness one of the DNA repair enzymes used by the mussel," Dr Dixon said.

DNA repair is important for the mussel because the watery environment around the deep hydrothermal vents - known as "black smokers" because of the particles they emit - are among the most toxic natural habitats in the world.

The mid-Atlantic Ocean ridge runs north-south and results from a volcanic welling that is expanding the seafloor at a rate of 25 millimetres a year. The lava streams created in the process produce unusual underwater geological forms, spreading out over many miles.

Animals living around the vents have evolved to cope with extremes in temperature, pressure and potentially lethal concentrations of toxic heavy metals, which are dissolved from the rock by the heat.

The Bridge project has discovered a range of unusual animals and bacteria inhabiting the lava deposits, including clams, limpets, brittle stars, worms and shrimps.

The scientists bring specimens under high pressure to a laboratory in the Azores. There they are investigated for unusual adaptations which may be of commercial use, in either medicine or by industry, for instance in clearing up contaminated land.

Studies of the microbes living in such habitats - so-called extremophiles - are helping to uncover a range of new chemicals. They include an enzyme that is helping to amplify minute quantities of DNA found at scenes of crime.