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Shark
holds secret to human DNA The Straits Times, 8 Feb 05 Singapore scientists research gene sequencing of elephant shark Channel NewsAsia, 10 Feb 05 The Straits Times, 8 Feb 05 Shark holds secret to human DNA by Chang Ai-lien SHARKS and humans may not look like they have much in common, but scientists here reckon they can use them to unlock the secrets of our own DNA. Following a landmark study of the puffer fish that won international acclaim, researchers at the Institute of Molecular and Cell Biology here have picked the oddball elephant shark as their next project. For selecting that particular species, lead researcher Byrappa Venkatesh had scoured the world's fish markets, aquariums and pet shops. 'Sharks and humans are like distant cousins, sharing similar sets of genes as well as body plan and physiology,' explained Associate Professor Venkatesh. 'They have a well-developed immune system similar to humans, so by comparing the genes of both species, we should get useful clues to understanding human diseases.' The elephant shark is actually what is called a chimera - a type of 'jawed vertebrate' which shared an ancestor with humans 500 million years ago. More than a decade ago, Prof Venkatesh, together with Nobel laureate Sydney Brenner and other colleagues, recognised that the puffer fish genome could be used as a model for analysing the human genome sequence. Such analyses may lead to a better understanding of how human genes work and, therefore, better medical treatment. The work won the team Singapore's National Science Award last year. It also inspired the setting up of an international consortium in 2000 that went on to map the entire genome sequence of the puffer fish, or fugu. The fugu has the smallest known genome among animals with a backbone - with essentially the same genes as humans, but squeezed into one-eighth the space. The elephant shark genome is three times larger than the fugu's, but what makes it special is that scientists discovered that some genes it shares with humans are absent in the puffer fish. Said the institute's executive director, Professor David Lane: 'This shark genome offers tremendous potential to help unravel the complexity of our own DNA.' While the genomes of other vertebrates such as the mouse, rat, chimpanzee and chicken have already been sequenced, this has never been attempted on the shark family. Prof Venkatesh explained its importance: 'When you have animals that are very similar, such as the mouse and human, it's difficult to see what's important in this sea of similarity. 'But when you can compare it with the shark, the first creature to develop nervous and immune systems, then it's easy to see what stands out and these must be really important genes.' The team searched the globe for more than two years to come up with a shark that had a genome small enough to be sequenced easily. Their findings have been published in the latest issue of the renowned scientific journal Current Biology and talks are under way to develop a major international genome project. Prof Venkatesh said it has become second nature to look for promising fish during his overseas trips. 'I normally bring back the interesting ones to Singapore in styrofoam boxes packed with dry ice. Many eyebrows go up when they see the box in the plane.' Channel NewsAsia, 10 Feb 05 Singapore scientists research gene sequencing of elephant shark By Hasnita A. Majid SINGAPORE : A group of scientists has embarked on gene sequencing of the elephant shark in the hope of unravelling the mysteries of the human DNA. After two years of scouring the world's fish markets and aquariums, Dr B. Venkatesh finally found a vertebrae for his next gene sequencing project. Dr B. Venkatesh, Principal Investigator of Genome Project at the Institute of Molecular and Cell Biology, said: "Sharks are the most ancient living jawed vertebrae. "They are like our distant cousins and they have very developed immune system, central nervous systems just like humans, so by studyng sharks we can get an idea of the ancestor state of all the genes." Dr Venkatesh said the genes of the elephant shark, which has lived for over 500 million years, would be able to act as master genes. Comparing them with human genes will show which genes have mutated over the centuries and give a clue on how genetic diseases occur. Dr Venkatesh said: "By sequencing and comparing with the human genome, we can spot the important sequences in the genome so they are likely to be very important to the function and regulation of the gene. "Probably some of them will be involved in the genetic diseases as well, so it will give us an insight to look into the cause of genetic diseases in humans." But with about 1,200 million base pairs of DNA in the elephant shark to be deciphered, Dr Venkatesh says it is like looking for a needle in a haystack. It is no wonder that after one year, only 2 percent of the genes have been sequenced. So to speed up the process, there are plans to set up an international consortium to help with the sequencing and develop a collaboration. Dr Venkatesh and his team are no strangers to gene sequencing, having been the same team that successfully sequenced the puffer fish genes - a project that received international attention for being a pioneer in this field. The puffer fish project, which he started with Nobel Laureate Sydney Brenner, has already been recognised as a model for analysing the human genome sequence. But some genes that are present in the human genes and the shark genes are absent in the puffer fish. The latest project on the elephant shark has been published in the renowned scientific journal Current Biology. - CNA links Related articles on Putting a price on nature in Singapore |
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