Conference highlights studies on metabolism, aging and monarch butterfly migration

Mar 12 2012

The Genetics Society of America's 53rd Annual Drosophila Research Conference, March 7-11 at the Sheraton Chicago Hotel & Towers, will showcase diverse efforts to understand basic biological processes through the easy-to-study fruit fly, Drosophila melanogaster, and other insects. Drosophila provides the ideal model system for studying biological questions, including many with direct application to human health. Three of the twelve plenary sessions illustrate the breadth of topics that will be presented at the meeting: metabolism, aging, and monarch butterfly migration.

One session will feature new findings that apply to diabetes and other metabolic disorders:

Carl Thummel, Ph.D., professor of human genetics at the University of Utah School of Medicine, and his group are using Drosophila to model human metabolic disorders. Thummel points out that flies provide a surprisingly good opportunity to study these disorders. He explains that "exposing flies to a high sugar diet leads to hallmarks of type 2 diabetes, including elevated levels of circulating sugar, increased whole-body fat levels, and insulin resistance." Flies on a high fat diet rapidly gain body fat and develop heart problems that resemble those seen in people with diabetes. Dr. Thummel's team is using Drosophila to probe the molecular mechanism of certain metabolic changes in flies that are seen in human cancer. "In addition, drugs such as sulphonylureas, which are used to treat diabetes, and Orlistat, a popular over-the-counter weight loss drug, have similar effects in flies to those seen in humans," Dr. Thummel says. This work demonstrates how identifying connections between flies and people can accelerate drug discovery and improve our understanding of the causes of metabolic disease.

Another session will explore the relevance of Drosophila research to concerns about aging:

John Tower, Ph.D., professor of molecular and computational biology at the University of Southern California, leads a group that uses the fly to investigate changes associated with aging, which "appear to closely parallel those in humans," he says. These events range from the molecular (changes in gene expression), to the subcellular (mitochondrial malfunction), to whole-body phenomena such as inflammation and muscle atrophy, to behaviors such as alterations to fly circadian rhythms.

At center stage in aging are the mitochondria, the cell components that house the reactions that use oxygen to extract energy from nutrients. "Aging disrupts the normal signaling between a cell's nucleus and its mitochondria, and also fails to maintain the mitochondria, increasing oxidative stress," Dr. Tower explains. Oxidative stress, which damages many cell parts, lies behind many human ills.

Dr. Tower and his colleagues can label and follow the expression of key genes to tell when a fly is close to death. This allows them to investigate the genes behind longevity. Dr. Tower says looking for increased life span "is the 'gold standard' for identifying a gene that is truly involved in aging."

Research presented at the Drosophila Research Conference also helps us understand such diverse phenomena as butterfly migration:

Every autumn, millions of eastern North American monarch butterflies fly to a particular patch of fir groves high in the mountains of central Mexico, a trip of up to 2,500 miles from their summer home. In the spring, the butterflies resume their journey, depositing fertile eggs on baby milkweed plants in the southern United States. Two more generations pass before the butterflies return to the population's northern home. The entire trajectory is encoded in the butterfly's genes; in fact, it can't be learned, because a single insect does not complete the entire flight.

How does an animal as simple as a butterfly know how to migrate? That's what Steven Reppert, M.D., Higgins Family Professor of Neuroscience at the University of Massachusetts Medical School, and his co-workers investigate. The team published the butterfly's genome sequence in 2011.

Migrating monarchs follow a "time-compensated sun compass" that senses the passage of the sun in the sky while simultaneously considering the passage of time. "Sky light information enters through the eyes and follows a complex circuitry to get to a brain region, the central complex, where it is integrated. The circadian clock that provides the time component and allows the butterfly to compensate for the sun's movement resides in the antennae," Dr. Reppert explains. A biological clock in the antenna that regulates a central brain behavior is a new finding, he adds.

"We're trying to connect the pieces. We don't yet know how the clock actually talks to the sun compass," explains Dr. Reppert. But comparing the genomes and gene expression patterns of butterflies on the various legs of their multi-generational journeys should fill in the blanks.

Source: Genetics Society of America