Honey bee genome being sequenced
The department of entomology at Texas A&M University is abuzz with the news the honey bee genome is being sequenced by the Baylor College of Medicine Human Genome Sequencing Center, especially since Texas A&M helped that project take flight.
The honey bee queen whose drones are the source of the DNA being sequenced at Baylor (Photo by Woody Welch and provided by Bee Weaver Apiaries Inc.)
"This is a huge deal," said Dr. Spencer Johnston, professor of entomology with the Texas Agricultural Experiment Station.
The honey bee was one of five species recently selected by the National Institutes of Health to have its genome sequenced. The NIH funds much of that type of work in the United States.
Texas A&M and the states beekeeping industry contributed the money to buy the large bacterial artificial chromosomal libraries needed for the project, and Baylor began the data collection recently, Johnston said.
"When you take an animal and clone him out, you have a choice on how big a piece you clone," he said.
"We just went crazy and made the biggest possible pieces, the biggest number we could afford. We have a tremendous bank of all the chunks of DNA of the honey bee. Twenty-five times over we have the honey bee genome, and all of these assembled chunks are called libraries."
Each living cell contains long strands of DNA, or the genetic code that contains all the information to create and control each cell in an organism, according to the UniSci international science news Web site.
DNA resembles a long, spiraling ladder, and the rungs of the ladder are made up of chemical units called bases. The clusters of bases make up genes, which determine inherited physical traits and much of behavior. Sequencing all of this genetic information, or the genome, requires identifying and determining the order of billions of bases that make up DNA and individual genes, the Web site reported.
"The honey bee is the first agricultural species to be sequenced. For that reason, its important," said Dan Weaver, co-owner of B Weaver Apiaries in Navasota.
The strength of the Honey Bee Genome Project proposal to the NIH lay in several factors, Weaver said. It pointed out the honey bee:
-Has a incredibly complex social behavior. Honey bees have internal cohesion and success in dealing with the many challenges posed by social life, including those related to communication, aging, social dysfunction and infectious disease.
-Has an enormously sophisticated cognitive ability, despite having a brain thats only half again as large as a fruit fly, Weaver said.
-Has an extraordinary ability to communicate. Honey bees are the only known examples of animals having symbolic language other than humans. For instance, through "dances," they communicate the location of nectar sources and flowers to their nest mates.
-Lives in an environment thats very humid and warm, ideal conditions for culturing bacteria and other pathogens. Yet, honey bees remain remarkably refractory and resistant to disease, Weaver said.
-Has sophisticated cognitive abilities to maximize foraging success. Honey bees are excellent at associative learning, based on the need to associate a color, shape, scent or location with a food reward.
In fact, honey bees are being studied by the U.S. Department of Defense as sentinel species that could detect and locate agents of harm, such as chemical or biological threats.
"It would appear their olfactory capabilities are at least on par with a dog, if not more sensitive," Weaver added.
According to Johnston, the honey bee also is "haplo-diploid." In a sense, each bee chromosome is a X-chromosome, with one copy in the male and two copies in the female, he said.
Mutations on the X-chromosome in humans are responsible for many serious conditions, including Turners syndrome, Trisomy-X, Kleinfelters syndrome, hemophilia, colorblindness and fragile-X syndrome.
Sequencing the honey bee genome would enable comparative analyses to address questions about gene expression, sexual development and X-chromosome-related diseases, he said.
Such factors are important to the NIH, Weaver said. "NIH is more interested in the relevance to human health," he said.
Also, the proposal also pointed out the role honey bees play as pollinators of agricultural crops; the economic value of pollination, about $15 billion annually.
"Another way to think of it is that one out of every three bites of food was produced or qualitatively enhanced by insect pollination," Weaver said.
Baylor will do all the sequencing seven to eight times over. "To our best guess, thats 270 million bases done at least seven times over," Johnston said.
The data collection is expected to be completed in about six weeks, Johnston said.
Then Baylor will generate an assembly of that sequence, using sophisticated software to put the billions of pieces of information back together again. Weaver likened it to someone taking seven catalogs, tearing them into tiny pieces, scattering them all over the floor and telling someone else to piece them back together again.
"We dont know when that particular aspect will be completed," Weaver said.
The Africanized honey bee genome also will be sequenced.
Annotation of the honey bee genome sequence will follow, Weaver said.
"Once you have an assembled sequence, then you have to make sense of it. You have to identify which are genes, where are they located, what are the regulatory elements that control the genes, how are these genes are turned on and off, what are the genes they lie adjacent to, how they compare to similar organization of common functionality in the mouse or human or fruit fly."
The genome annotation will be a collaborative effort, led by Baylor, and include the National Center for Biotechnology Information, honey bee and insect researchers, and Texas A&M "bioinformatics," or computer resources.
The information available through NIH is generally displayed in comparison to the human, Weaver said.
"Its a lot more difficult to compare other species among themselves. We hope the bioinformatics at Texas A&M will allow direct comparisons of genomic information of agricultural species."
Also, "as an agricultural school, Texas A&M will find the information useful in producing bees that are less defensive, pollinate more efficiently and produce more honey," he said.
"Ultimately, its about more and better food on your table, easier and better ways to control Africanized honey bees, improving human health and providing new tools for medicine" he said.
The initial call for sequencing the honey bee came from Weaver, whose contact with Richard Gibbs and George Weinstock, Baylor HGSC co-directors, led to a meeting in December 2001 of honey bee scientists and experts in insect genomics from across the nation, as well as genomics experts from Baylor and the U.S. Department of Agriculture.
Organized by Weaver and hosted by Baylor, the meeting was called to begin developing a "white paper" in response to a call from the NHGRI for the research community to suggest the most important and interesting organisms for sequencing upon the conclusion of the human genome project.
The Honey Bee Genome Sequencing Consortium was formed at the December meeting, and members, which included Weaver and Johnston, drafted and submitted the HBGP proposal.
Edith A. Chenault | EurekAlert!