For more than a century, countless generations of Drosophila, a.k.a., fruit flies, have lived and died to further the investigations of enquiring scientific minds.
Geneticists in particular have profited from close observation of these rapidly reproducing creatures, chiefly because the fruit flies' genome, though tiny compared to that of human beings, contains important similarities to our own. The Drosophila genome was fully sequenced in 2000. Since then fruit fly research has led to discoveries related to the influence of genes on diseases, animal development, population genetics, behavior, physiology, evolution, cell biology, and neurobiology.
Now a discovery by an MU researcher, recently published in the Proceedings of the National Academy of Sciences, promises to extend these gains.
Troy Zars, an assistant professor of biological science in the College of Arts and Science, used Drosophila to explore the well-documented but little-understood process by which animals match the "quality" of a memory with its significance. How significant events, in other words, produce memories that are stronger, last longer and are more easily recalled than remembrances of a more trivial nature.
Zars had previously determined that manipulating levels of chemical compounds in the Drosophila brain allowed him to isolate and test genes related to memory. Next, he put individual flies to the test. First he deposited an individual fly into a heat-equipped chamber in which it could wander freely. When the fly buzzed over to a predetermined side of the chamber, it tripped a sensor that fired up the heating element and made the chamber uncomfortably warm.
Normal flies eventually learned, or remembered, to avoid tripping the sensor. Flies bred with genetically altered serotonin and dopamine levels, on the other hand, consistently failed to beat the heat -- a finding that suggests genes involved with these neurotransmitters could play a role in memory retention.
This discovery, and others it presages, could lay the groundwork for a better understanding of cognitive decline in patients suffering from neurological disorders such as Parkinson's and depression, Zars says. "We have developed a strategy to address how this matching occurs, so we can 'turn that crank' over and over again. It allows us to answer the questions: 'What gene is it? How does it function? How does it interact with other proteins?' We can find brand-new, completely unexpected things."