Deadly fish reveals hidden human genes

 作者:毛浚     |      日期:2019-03-05 01:02:02
By Nicola Jones The first comparison of the entire human genome with another vertebrate has been published – it predicts the existence of 900 as-yet undiscovered human genes. The comparison was made with the pufferfish, following the sequencing of its DNA by a consortium from Singapore, the UK and the US. Ever since sequencing of the human genome, researchers have been rushing to catalogue the DNA of other creatures. Scientists believe these will provide valuable compare-and-contrast tools to help to sort out genes from junk in human DNA. Projects on the mouse, zebrafish and the pufferfish Fugu rubripes have been running for months or years, with results posted on the web as they become available. But by using a quick sequencing method called whole-genome shotgun, the pufferfish project has become the first to publish analysed results. The pufferfish was chosen because it is one of the most ancient vertebrate relatives of humans – the two lineages split about 450 million years ago. It also has a compact genome, with roughly the same number of genes as humans but only 10 per cent of the total number of “letters”, or base pairs. The team uncovered a few surprises in the fish’s genome, such as the fact that a few fish genes are up to four times bigger than their counterparts in humans. “We find that very puzzling,” says Samuel Aparicio, lead author of the Science paper. The researchers also found that the fish have a huge variety of so-called “jumping genes”, repetitive bits of DNA that have a tendency to copy themselves. However, these genes have not accumulated in the fish to any great degree, taking up just 15 per cent of the genome. In humans, they fill more than half the genome. Some researchers have doubted the ability of the whole-genome shotgun approach to handle complex genomes and were cautious of Celera’s human genome data because of its shotgun assembly. But Aparicio, who works at the University of Cambridge, says their effort proves that a reasonably complicated genome can be easily put together this way. “The sequencing only took a few months,” he says. They anticipate it will take until April 2003 to complete the sequence, by which time they expect they may have dug up another thousand human gene candidates. Potential genes are identified by comparing the proteins that would be produced by the pufferfish DNA with a database of human proteins. Matches that are not linked to human genes already known about signal a possible new gene. A similar paper analysing the mouse genome is expected to appear later in 2002. And other projects looking at the genome of rats, apes, frogs and even chickens are in progress. Journal reference: Science (DOI: