Written By Thi Ngo
Brain research is crucial to understanding life. However, it is complicated by ethical issues that prevent researchers from obtaining human brain samples to perform experiments with. This calls for the utilization of model organisms for researchers to uncover brain functions. Similarities in brain structure and connectivity between rodents and human make mice a particularly popular choice in brain research. However, studies using mice are often costly and time-consuming. The fruit fly, Drosophila melanogaster, has recently emerged as a valuable organism to study neurobiological processes on. Due to its short generation time, low maintenance cost, and availability of genetic tools, fly studies have sped up discoveries in brain research . Flies offer the advantage of having a much simpler, yet surprisingly similar, nervous system to humans which allows researchers to understand the specific molecular interactions underlying brain processes . At the University of California, Irvine, several research labs are harnessing the power of the fly to study epilepsy and the neuronal basis of circadian rhythm.
At the O'Dowd lab, researchers are using Drosophila to understand epilepsy. In humans, hallmarks of epilepsy include loss of consciousness, uncontrollable shaking, and seizure episodes. These symptoms are normally absent in healthy people due to the action of inhibitory neurons, which are brain cells that keep neural excitability in check. Inhibitory neurons function through ion channels, which are proteins serving as “gates” for ion movement that induce brain signals . Thus, mutations in ion channel genes prevent inhibitory neurons from performing their function, leading to uncontrollable brain activity. Interestingly, similar mutations in flies also lead to typical human epileptic symptoms. Flies harboring these mutations display uncoordinated motion such as frequent falling or excessive twitching. The O’Dowd lab found that such mutations are heat-sensitive and that more severe forms of epilepsy correspond with stronger dependence on temperature elevation. Despite this, the epileptic symptoms are dampened upon feeding flies with the neurotransmitter serotonin which suggests that the serotonin pathway is a promising therapeutic target for epilepsy . The researchers hope to use these results to understand seizure regulation and to develop more effective treatment for epilepsy.
Not only are fly brains useful for studies concerning neurological diseases, but they also give us insights into a social phenomenon called “social jet lag.” This phenomenon is characterized by a disrupted sleep cycle caused by social activities. To understand the underlying mechanism of “social jet lag,” dissected fly brains are flashed with intermittent pulses of light to mimic an unnatural sleep cycle. Researchers then measure the protein levels of key genes in different subsets of brain cells. They discovered that when the brains are exposed to unnatural light patterns, some neurons become desynchronized and express certain proteins at the wrong time and for the wrong duration. Desynchronization of brain cells is particularly sensitive to light with blue wavelength, which is typical for light emitted from electronic devices . With these results, the research lab hopes to understand the health implications of nighttime cell phone usage, evening work hours, late-night college parties, and other forms of circadian disruption.
Above are just two examples among numerous other studies that utilize the fruit fly’s brain to uncover human biological processes. A lot of our own biology can still be learned from these seemingly “lower” organisms. Meanwhile, the next time you see a fruit fly hovering over your bananas, remember to say “thank you" before swatting them away.