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Columns::December 2, 2002
$6.3 million gift to Georgia Museum of Art honors painter
$3 million in new grants, contracts will support research on weapons of mass destruction
Seminar focuses on UGA’s role in building ‘emergency-response community’
MRI now available for veterinary patients
Fall enrollment up at UGA and Gwinnett University Center
Professor’s childhood interest in botany blossoms into career in plant pathology
Fanning Institute appoints associate director
Kudos
The bottom line
Military briefing
Campus News
What all the buzz is about
Scientists discover genes that may help control transmission of malaria by the Anopheles gambiae mosquito
By Phil Williams
phil@franklin.uga.edu
A team of UGA scientists, using bioinformatics approaches, has discovered 35 genes that contain important regulatory peptides
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| Mark Brown (from left), Stephen Garczynski and Joe Crim used bioinformatics approaches to find regulatory genes in the malaria mosquito. (Photo by Peter Frey) |
in Anopheles gambiae, the malaria mosquito. The new information could point toward ways to control the disease, which kills millions of people worldwide each year.
Included in the 35 are five genes that encode insulin-like peptides that probably have pivotal roles in the life cycle of the mosquitoes. Interfering with the action of these genes on a large scale could keep the mosquitoes from passing on parasites that cause malaria.
“It is important to know as much as possible about how these insects transmit malaria,” says Mark Brown, an associate professor of entomology at UGA and a specialist in mosquito biology. “These genes offer new information on the regulatory processes that make the transmission of disease possible.”
The research was published earlier this fall in the journal Science and was funded by the National Institutes of Health.
Other researchers involved are Joe Crim and Stephen Garczynski of the department of cellular biology; Michael Riehle, an entomologist, like Brown, from the College of Agricultural and Environmental Sciences; and Catherine Hill of the University of Notre Dame.
Malaria is one of the planet’s deadliest diseases and one of the leading causes of sickness and death in the developing world. According to World Health Organization statistics from the late 1990s, there are 300 million to 500 million clinical cases of malaria each year, resulting in 1.5 million to 2.7 million deaths.
Children aged 1 to 4 are the most vulnerable to infection and death; malaria is responsible for as many as half the deaths of African children under the age of 5. Each year, the disease kills more than one million children—2,800 per day—in Africa alone. In regions of intense transmission, 40 percent of toddlers may die of acute malaria.
Anopheles, the African malaria mosquito, develops rapidly in water, and its reproduction cycle begins with successive blood meals from humans. Regulatory peptides acting as neurochemicals and hormones govern these processes in mosquitoes, so describing and understanding these peptides are crucial steps toward control.
“At this point the exact function of these genes is speculative,” says Crim, a peptide-reception biologist. “None of these regulatory peptides was previously known for Anopheles. But their importance is clear.”
This study was part of the functional completion of the genome for Anopheles gambiae, in which a number of laboratories participated. That achievement could have an enormous impact on future control of the Plasmodium parasites with which Anopheles infect humans with malaria.
The University of Georgia team used bioinformatics—the study of gene databases on computers—to determine peptide-encoding genes in the Anopheles genome. Of particular importance were the five insulin-like peptides. The scientists followed intriguing hints that Plasmodium appears to use insulin from either the female mosquito or the vertebrate blood meal for its own development, metabolism and reproduction. That connection could be crucial to understanding how the parasites are passed to humans and create disease.
“Since most peptide types exist as single-copy genes, each is a target for genetic interference,” says Brown, “both to unravel regulatory functions and in the long term to engineer Anopheles where it is less hospitable for Plasmodium.”
Crim says the computer program the team used looked for genetic sequences and identified candidates for regulatory genes. Though there may well be more than the 35 the team found, these are the first and most obvious targets for intervention. The completion of the A. gambiae genome means scientists can now compare genetic elements to other completed “gene maps,” in species such as the fruit fly, for example.
Finding the genes and their locations on the chromosome is a beginning, but more in-depth knowledge will be necessary before the researchers can find a way to make the mosquitoes less likely to deliver parasites that cause malaria.
To this end, the scientists at UGA have begun to clone the genetic sequences and express them; they will soon be able to determine their precise regulatory function in the mosquitoes and to identify the receptors that allow the parasites to infect humans. |
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