Washington

The chimpanzee, chicken and honeybee are among the top priorities for genome sequencing selected by the National Human Genome Research Institute (NHGRI) in Bethesda, Maryland. The announcement on 22 May sparked equal measures of jubilation and despair among researchers who had been lobbying the institute to fund projects for their favourite organism.

Other priorities include the sea urchin Strongylocentrotus purpuratus and the protozoan Tetrahymena thermophila. Fifteen fungi make up the remainder of the list.

There will be arguments among scientists about each selection, but the main point of controversy is the choice of the chimpanzee ahead of the rhesus macaque, which is more widely used in biomedical research but is listed as only a “moderate” priority.

The main NHGRI-funded sequencing centres — at the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, Washington University School of Medicine in St Louis, Missouri, and Baylor College of Medicine in Houston, Texas — are fully occupied with the human, mouse and rat genomes. But as these projects wind down over the coming months, spare sequencing capacity will open up, so the NHGRI asked researchers to submit 'white papers' making the case for the next round of organisms to be sequenced. An expert panel reviewed a list of 13 bids, ranging from the green turtle to the cow.

Individual sequencing projects will still have to be approved one by one. But given the immense opportunities offered by genomics, advocates of particular model organisms had invested high hopes in getting onto the NHGRI's priority list. “Working on a system that doesn't have a sequence available is like doing research with one hand tied behind your back,” observes Eric Green, director of the NHGRI's own sequencing centre.

The priorities highlight animals useful in agriculture, such as the chicken and the honeybee, but not plants, for which sequencing projects are funded by the National Science Foundation and the US Department of Agriculture. The agriculture department is also expected to collaborate with the NHGRI in work on the chicken and honeybee genomes.

Fungi are included because they cause human and agricultural disease. Both the sea urchin and the chicken are model organisms for developmental biologists, and Tetrahymena is used in cell biology and genetics research, particularly for studies of the telomeres that cap the ends of chromosomes, which shorten as cells age. “The biologists who work on these organisms are really energized by this,” says Richard Gibbs, director of Baylor's sequencing centre.

Members of the selection panel say they tried to select a range of organisms to allow evolutionary and comparative studies. Advocates for the chimpanzee, which is thought to have a genome 98.5% genetically identical to our own, argue that comparisons between the two sequences could yield clues about the origin of human cognitive abilities and language. They also say that the sequence could help to explain why chimpanzees do not get diseases such as breast cancer and Alzheimer's — offering potentially important medical insights.

But these arguments cut little ice with researchers who have been lobbying for the rhesus macaque to be made the top-priority primate. Macaque advocates feel that the panel was swayed by the public appeal of sequencing our closest relative, and point out that scientists can do little work on chimpanzees because of welfare concerns and the animals' endangered status.

“It is a tragedy that the NHGRI is committing these resources to sequencing the chimpanzee genome when there are so many investigators using rhesus monkeys who desperately need a sequence to advance research,” says John VandeBerg, director of the Southwest National Primate Research Center in San Antonio, Texas. He argues that rhesus macaques provide vital models in research on many human diseases. They are particularly important in attempts to develop vaccines against HIV, and are widely used in basic neuroscience studies.

But the macaque might still win favour in the future. The NHGRI's priorities panel will review white papers three times a year from now on. And researchers can revise and resubmit their proposals, says Jane Peterson, programme director for large-scale sequencing at the NHGRI. “We don't consider the high-priority bin to be static,” she says.

→ http://www.nhgri.nih.gov/NEWS/sequencing.html