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Sequencing priorities
Chickens and chimps get a boost; second fruit-fly genome tackled


What do sea urchins, honey bees, chickens, chimpanzees and fifteen species of fungi have in common? These organisms have been given "high priority" rankings by the National Human Genome Research Institute (NHGRI) for future genome-sequencing projects at the major centers supported by the institute.

The reason for setting those priorities, NHGRI officials say, is to develop a pool of candidate organisms from which NHGRI-funded centers can choose to start sequencing after they complete their work on the human, mouse and rat genomes.

The major NHGRI-funded centers are the Whitehead Institute/MIT Center for Genome Research, in Cambridge, Massachusetts; the Genome Sequencing Center at the Washington University School of Medicine, in St. Louis, Missouri; and the Human Genome Sequencing Center at Baylor College of Medicine, in Houston, Texas.

"This priority-setting is an unprecedented activity, and it needs to be done relatively quickly because we want to take advantage of the sequencing capacity as it becomes available," says George Weinstock, co-director of Baylor's Genome Sequencing Center.

Here are the "high-priority" organisms, along with some reasons cited for the ranking:

The chicken (Gallus gallus) is used for research on embryo development and other biomedical research issues, and is the only bird species with enough research resources in place to justify a major genome-sequencing project.
The chimpanzee (Pan troglodytes) is closely related to humans, and comparing the human and chimp genomes may provide insights into medical conditions that affect humans and not chimps.
The honey bee (Apis mellifera) is a model species for the study of antibiotic resistance, immunity, allergic reactions, longevity and X-chromosome diseases.
The sea urchin (Strongylocentrotus purpuratus) is an important model system for the study of developmental biology because of its evolutionary position.
The protozoan Tetrahymena thermophilia is used for studies of the structures of telomeres (the ends of chromosomes) and the telemorase enzyme.
Fifteen species of fungi were also given high-priority ratings because of their significance in various research fields, including medicine, evolutionary biology, and agriculture. Those species include three Aspergillus species and Serotype A of Cryptococcus neoformans.

In addition to those high-priority rankings, the rhesus macaque monkey (Macaca mulatta) and a one-celled animal species (Oxytricha trifallax) were given a "moderate priority" ranking for sequencing. Reviewers deferred consideration of a proposal to sequence the cow genome until 'white papers' outlining the arguments for other large mammals—dogs, cats and pigs—are considered later this year.

While he was surprised that the rhesus macaque monkey was not ranked as a "high priority" project, Weinstock says he thinks the selection process has been handled well. Advocates of sequencing the rhesus macaque's genome have expressed disappointment because the monkeys are used in research far more often than chimpanzees.

As part of the NHGRI's prioritization process, groups of scientists who favored particular organisms got together and submitted detailed white papers to argue for their selection. A panel of scientists then reviewed those papers and recommended priority organisms. In late May, the National Advisory Council for Human Genome Research approved the list. Scientific white papers on other candidate organisms are being developed for submission to the NHGRI for another round of consideration later this year.

In a separate decision this spring, NHGRI awarded a grant to the Baylor College of Medicine's Human Genome Sequencing Center to sequence the genome of a second fruit-fly strain, Drosophila pseudoobscura. Its genome will be compared with that of the common fruit fly, Drosophila melanogaster, whose whole-genome sequence was published in March 2000. An NHGRI official said Baylor's Drosophila pseudoobscura grant had been in the pipeline before the current genome prioritization process.

The second fruit-fly strain was chosen for sequencing because it has "a reasonable evolutionary distance" from Drosophila melanogaster but at the same time is closely enough related to make the genomic comparison useful, according to Weinstock. Also, the D. pseudoobscura strain's genome is of interest in itself because it has been used for several fruit-fly population and environment studies.

For more information see the NHGRI press release and the Baylor press release.

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NHGRI prioritizes next organisms to sequence. Press release, The National Human Genome Research Institute (NHGRI), Bethesda, Maryland (May 22, 2002).
Baylor awarded $5 million to sequence fruit fly genome. Press release, Baylor College of Medicine, Houston, Texas (May 20, 2002).

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