Credit: André Karwath
Even if you haven’t worked directly with Drosophila melanogaster in a biology course or a research laboratory, you’ve probably seen it first-hand. D. Melanogaster, the common fruit fly, can be seen near almost any trash can or bowl of fruit that has been sitting in sunlight too long. Most scientists refer to the species simply as Drosophila, even though technically there are about 1,450 species in the Drosophila genus.
The 2.5-millimeter-long insect rose to fame in the early 20th century after the biologist Thomas Hunt Morgan used it to show that genetic variations in all organisms are conveyed via the chromosomes contained in cells. Morgan’s work with Drosophila eventually earned him a Nobel Prize, and his student H. J. Muller followed suit. Today Drosophila remains a workhorse in biology labs around the world. The same qualities that make it such a persistent pest—its hardiness, rapid reproduction cycle, and small size—also make it attractive to researchers. Morgan first started using Drosophila for his research because he had limited lab space. The tiny flies were perfect for his cramped New York lab.
But a recent decision at the International Commission on Zoological Nomenclature (ICZN) may have a startling consequence: Soon, Drosophila melanogaster may not be the subject of any research at all. As Michael Bok, a graduate student at the University of Maryland, Baltimore County, noted on his blog, on April 1, the ICZN determined that Drosophila melanogaster is almost certainly misnamed.
The problem is that the genus Drosophila is part of a larger family of flies, spanning many different genera. As it turns out, some “Drosophila” are actually more closely related to Samoaia, Captomyza, or Hirtodrosophila. The original member of the Drosophila genus, D. funebris, first described in 1787, is more like Samoaia than D. melanogaster. That means that the Drosophila so many scientists know and love will likely be renamed Sophophora melanogaster.
Not since Brontosaurus became Apatosaurus has the world of nomenclature been so shaken. Some wonder whether scientists will even adopt the new terminology. With thousands of research papers referring to Drosophila, will anyone bother with the “correct” Sophophora?
In case they do, I thought it might be a good time to take a nostalgic look at some of the amazing work that has been done with this persistent little bug. While Drosophila melanogaster was first used to study genetics, it’s now studied in a wide range of fields. Last October Mo Costandi, a freelance science writer based in England, discussed an elegant study of the fruit fly brain that used laser pulses to give the flies false memories.
Despite its tiny 250,000-cell brain, D. melanogaster can easily be trained to avoid odors they ordinarily would be attracted to: Researchers give them a tiny electric shock when in the presence of a particular smell. A team led by Adam Claridge-Chang wanted to know what caused this response, so they created a mutant strain of Drosophila that produces dopamine when exposed to light. Dopamine is believed to be involved in the formation of the memories that cause the flies to avoid unpleasant stimuli. Next the flies were successfully trained to avoid an odor using the flash of a laser instead of an electric shock. Although the laser isn’t painful to the flies, their behavior was indistinguishable from flies that were trained using shocks. Using this and other techniques, the researchers were able to pinpoint the region of the fly’s brain responsible for learning to avoid the odor, encompassing just 12 brain cells. Their work was published last year in Cell.
Björn Brembs, a neurobiologist at the Freie Universität Berlin, has done similar work with D. melanogaster, but with a twist. He and Bruno van Swinderen found that mutant fruit flies with memory problems also exhibit erratic flight patterns. These flies, unlike the ones Claridge-Chang’s team studied, were difficult to train. Brembs and van Swinderen were studying how the flies flew using a miniature flight simulator. The apparatus keeps the flies stationary while a display presents the illusion of flight. The flies with the mutation turned much more frequently than normal wild flies. Brembs thought the mutant flies’ behavior resembled ADHD—a human attention disorder that is also associated with learning difficulties. So Brembs and van Swinderen tried treating the flies with Ritalin—the same drug often used to treat ADHD. Amazingly, the treated mutant flies now performed nearly identically to wild flies. The work was published in the Journal of Neuroscience.
Brembs says he isn’t sure exactly why Ritalin works on these flies, whose brains are barely a millionth the size of a human brain, but he believes that this research is only the beginning of what he may accomplish using the flight simulator to track Drosophila flight and walking behavior.
Kim Van der Linde, one of the scientists who opened the debate about naming Drosophila by formally proposing to the ICZN that the appellation “Drosophila melanogaster” be preserved, has a blog of her own where she has offered her reactions to the ICZN decision. She points to a case where a name change was not accepted, with resultant confusion in the scientific literature. She still believes it would be simpler to keep the same name for the frequently-studied Drosophila melanogaster, while changing the less-influential other members of the family, even if in the end it means far more insects will have to be renamed. She might be right—otherwise, we may be faced not just with renaming a thousand or so insects, but changing thousands of papers, and untold numbers of textbooks and course curricula. And it appears that some scientists have begun to protest the ICZN decision.
However the naming dispute is resolved, research on the common fruit fly will continue, and you can find out about it by searching for Drosophila (or Sophophora, as the case may be) on ResearchBlogging.org.
Dave Munger is editor of ResearchBlogging.org. He also blogs at The Daily Monthly. Each week, he writes about recent posts on peer-reviewed research from across the blogosphere. See previous Research Blogging columns »
Originally published April 21, 2010