Puffer fish yields human gene clues

Fugu rubripes is a famously dangerous dish

		By BBC News Online's Ivan Noble

The human body's genetic make-up is surprisingly similar to that of the puffer fish, Fugu rubripes, of Japanese culinary fame.

For the bits that count it's extraordinary how similar we are

Greg Elgar

That is one of the conclusions of a year-long international effort to sequence the fish's genome.

"For the bits that count it's extraordinary how similar we are," Dr Greg Elgar of the UK Medical Research Council's Human Genome Mapping Resource Centre told BBC News Online.

The fish's DNA has proved easier to map than that of the human body and scientists believe there will be medical applications for their new knowledge.

Comparative genomics

"This information will have enormous benefits to scientists working on the human genome and will certainly be instrumental in the fight against genetic disease," said Dr Elgar.

The sequencing effort, which took a day under a year to complete, is part of the efforts scientists are making to understand and apply the information derived from decoding the human body's own programme for reproducing itself and staying alive.

One of the best ways of doing this is to compare humans with other organisms.

All organisms contain DNA, but most of the DNA in the human genome is what is sometimes called "junk DNA".

It is made up of sequences of bases often repeating and with no clear function.

Picking through 'junk'

The puffer fish genome is much smaller than the human one, but it still has many of the same basic genes.

This makes it easier to pick out the genes from the junk.

And Fugu rubripes, despite all its differences, still needs many of the same basic genes as humans to survive.

"When we compare stretches of the human genome with the F. rubripes genome, only small pieces look alike. These are the genes," explained Dr Elgar.

Essential tasks

Throughout evolution, the DNA of all organisms has been subject to random mutations.

Mutations which give their host some kind of benefit have survived, while harmful mutations have ultimately killed off their hosts and any offspring.

Many of these useful mutations took place early on in Earth history and are common to organisms as diverse as yeast, fruit flies, humans and the puffer fish.

"They have to be there because each one of them does an essential task like develop a leg or fin or haemoglobin," said Dr Elgar.

The puffer fish genome was decoded by an international consortium, including the Joint Genome Institute in the United States, the Institute for Molecular and Cell Biology in Singapore, and the Human Genome Mapping Resource Centre in Cambridge, UK.