What do fruit flies, mosquitoes, silk moths and honey bees have in common? First, they are all insects. Second, they have all had their genomes sequenced, a feat that will make it much easier to discern both similarities and differences.
The honey bee (Apis mellifera) has just joined this elite club. Researchers at the University of Illinois at Urbana-Champaign, along with scientists at other institutions, have already begun probing the honey bee genome for its many secrets. The primary discoveries found so far are presented in the Oct. 26 issue of Nature, and in other scientific journals.
Why sequence the honey bee genome?
"Honey bees are the premier pollinators on Earth, and play a vital role in our nation's economy and food supply," said Gene Robinson, the G. William Arends Professor of Integrative Biology in the department of entomology at Illinois, and director of the U. of I. Bee Research Facility. "Honey bees account for 10 to 20 billion dollars of food produced in America alone, per year," he said.
Honey bees are also very valuable to scientists as model research organisms. "In biology and biomedicine, honey bees are used to study many diverse areas, including allergic disease, development, gerontology, neuroscience, social behavior and venom toxicology," Robinson said. "Because they live in intricate societies, we can view the traits that honey bees exhibit through a prism of extreme sociality."
The Honey Bee Genome Project originated in 1999 when Robinson and Daniel Weaver, a commercial beekeeper in Texas, joined forces to pitch the project. Robinson organized the academic community, while Weaver sought support from the bee industry.
With funding from the National Institutes of Health and the U.S. Department of Agriculture, the sequencing began in December 2002, and was performed by George Weinstock and colleagues at the Human Genome Sequencing Center at the Baylor College of Medicine in Houston.
To sequence a genome, researchers first extract the DNA and break it into tiny pieces. Each of those pieces of genetic material is then sequenced. Lastly, an elaborate computational process puts the pieces back together in correct order.
"It often takes time to translate a genome sequence into results of major scientific import," said Robinson, who is also a researcher at the university's Beckman Institute for Advanced Science and Technology and a theme leader at the university's Institute for Genomic Biology. "However, already some tantalizing findings have emerged that help us better understand the honey bee."
Among the major findings:
- The honey bee originated in Africa and spread into Europe by at least two ancient migrations. In the New World, introductions of the western and northern European subspecies began in North America as early as 1622. In 1956, the African "killer" bee was introduced to Brazil in an attempt to increase honey production. Descendants of these African honey bees have spread northward and southward, hybridizing with and displacing previously introduced European honey bees.
- Honey bees have many more genes related to smell, compared with fruit flies or mosquitoes, but far fewer genes related to taste. The enhanced number of odorant receptors underlies the honey bee's remarkable olfactory abilities, including perception of pheromones, kin recognition signals, and social communication within the hive. A large number of odorant receptors also allows the bees to find food and communicate the location of it to other bees.
- Researchers found clues for social cues, a form of bee pressure that can cause nurse bees to become foragers in response to needs of the hive. The job shift involves changes in thousands of genes in the honey bee brain; some genes turn on, while others turn off. A few "master regulator" genes known to function in the development of fruit flies have been implicated in regulating the activity of these thousands of genes. It appears that master regulator genes involved in nervous-system development in fruit flies are re-used by nature for behavioral functions in adult honey bees.
These early findings hint at the wealth of knowledge to be gained through further study of the honey bee genome, Robinson said. "The honey bee genome project is ushering in a bright era of bee research, for the benefit of agriculture, biological research and human health."
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