Model organisms, including animals, plants, and microorganisms, are readily used in research due to their short generation times, well-characterized and manipulable genomes, and/or similarity to humans. For example, the DNA of E. coli (a bacteria) and S. cerevisiae (a yeast) can be easily edited by researchers allowing them to observe which genes are important for certain functions. Furthermore, E. coli and S. cerevisiae grow relatively quickly. Another popular model organism is the fruit fly (Drosophila melanogaster). Not only does it reproduce quickly, making it easy to work with, but it is more similar to humans than you might initially think. For approximately 75% of disease-causing genes in humans there is a corresponding gene in fruit flies. For this reason, fruit flies are great models for studying human genetic diseases. Years of work has also shown that fruit flies are valuable models for the study of drug abuse.
Nicotine, the highly addictive chemical found in tobacco, is known to interact with specific molecules in the brain called nicotinic acetylcholine receptors (nAChRs). These receptors, normally activated by a molecule known as acetylcholine, play important roles in normal human physiology, specifically regulating learning, memory, and reward. By mimicking acetylcholine, nicotine can affect several different aspects of normal brain development. We still know very little about how nAChRs adapt to exposure to nicotine early in human development. Previous research has shown that babies exposed to nicotine before birth have more nAChRs in the brain, which can put them at risk for attention deficit hyperactivity disorder.
For the first time, fruit flies have been used to study the effects of nicotine exposure on normal development and on adult behavior. In her model, Norma Andrea Velazquez-Ulloa demonstrated that fruit flies reared on food laced with nicotine exhibited developmental delays, weight loss and shorter life spans. These results confirmed what had previously been seen in other studies looking at the effects of nicotine on humans, rodents, and zebrafish (another valuable model organism!). In addition, Velazquez-Ulloa associated one of the components of the nAChRs to nicotine-induced developmental delay.
According to the US National Survey of Drug Use and Health, 15% of pregnant women use tobacco. It is therefore important to understand how prenatal exposure to nicotine affects development. Velazquez-Ulloa provides a valuable new fruit fly model to further investigate the effects of nicotine on nAChRs activity and animal physiology.
Summary written by: Emma Finlayson-Trick
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