Pretty white for a fly guy
Genetics’ Top Model
Forget your leggy blondes and busty brunettes, muscled hunks and sexy, skinny guys, the undisputed top model in the world of genetics is, in my opinion, the tiny fruit fly that you’ll find buzzing round over-ripe bananas in kitchens all over the world.
This unassuming insect, known more formally as Drosophila Melanogaster, has played a major role in genetics research for more than a century, providing valuable insights into everything from the fundamental principles of development from a single fertilised egg to a fully-formed organism to human diseases such as cancer and dementia, netting at least five Nobel prizes along the way. In fact, it’s often said that the entire field of modern genetics simply wouldn’t be possible without these little critters.
But, you may be asking, who on earth stared at the flies buzzing round their fruit bowl and thought, you know what? They look like they’d be good for science.
That person was NOT Thomas Hunt Morgan - the name that most biologists associate with Drosophila. Instead it was Harvard professor William Ernest Castle, who first used fruit flies in 1901 as a way to speed up his research into coat colour in mice and guinea pigs - fruit flies cranking through a generation in less than a fortnight, much faster than mammals.
News of these fast-breeding flies started to spread, and in 1906, an entomologist named Frank Lutz suggested to a colleague that he might find some use for Drosophila, although Lutz himself hadn’t had a lot of success with the little flies himself.
And that person was Thomas Hunt Morgan.
Born in 1866 in Lexington, Kentucky, Morgan was the great-grandson of Francis Scott Key, composer of the "Star-spangled Banner." Intrigued by nature from an early age, he started off collecting bird eggs and fossils, moving on to marine animals and eventually landing on fruit flies as a way to explore the concepts of inheritance that were emerging at the time thanks to the rediscovery of Mendel’s laws of inheritance, sealing his reputation as one of the forefathers of modern genetics.
Morgan set up a special laboratory at Columbia University in New York, known as the ‘fly room’ - Schermerhorn room 613 on the 9th floor of a building that nestles between what are now the Art History and Biology departments. It was a dingy, cramped space more like a cupboard than a lab, stocked with bunches of rotting bananas and a group of extremely smart students nicknamed the ‘fly boys’- Hermann Muller, who later won a Nobel prize for showing that X-rays cause mutations, Alfred Sturtevant, who worked out how to map genes to specific locations in chromosomes, and Calvin Bridges, who was the lab’s top inventor, pioneering many of the scientific techniques that turned Drosophila into a powerhouse of genetic research.
And of course a big shout out to Edith Wallace - an artist with an incredible eye for detail who captured many of the lab’s research findings with her pencil and paper, and also did the grim and repetitive job of maintaining all the fly breeding stocks.
By 1910, Morgan had spent a year or so breeding regular or wild-type Drosophila, which normally have dark red eyes. But then one day he noticed a male fly with white eyes. Intrigued, he set this little chap to work breeding with its red-eyed sisters, tracing the pattern of inheritance down the generations and eventually figuring out that whatever was responsible for the White eyed fly must be on the X chromosome, one of the fly’s two sex chromosomes, leading to the discovery of sex-linked genes.
This set the scene for decades of detailed work, spotting strange characteristics in the flies such as extra bristles, curly wings, or legs growing out of their face, and carrying out multiple generations of breeding experiments, or crosses, to track down the faulty genes to various locations on the insect’s four chromosomes. And it eventually led to Morgan winning a Nobel prize in 1933 "for his discoveries concerning the role played by the chromosome in heredity", sharing the prize money with Alfred Sturtevant and Calvin Bridges. But not you, Edith.
Over the past 100 years, Drosophila melanogaster has played a powerhouse role in research - a quick search of the scientific literature reveals more than 50,000 papers that name-check these fruitful flies. Around 75% of all disease-related genes in humans are thought to have some kind of parallel version in flies, making them an important tool for biomedical research today.
They have underpinned major breakthroughs in neuroscience, starting with the discovery of a gene called Notch, which helps cells choose their fate. Fruit flies are now being used to model neurodegenerative conditions such as Alzheimer’s, Parkinson’s and Huntington’s diseases. Drosophila also played a key part in revealing the workings of circadian rhythms - the daily cycles of the body clock.
Finally, The German-American team of Janni Nusslein-Volhard and Eric Weischaus won a Nobel prize in 1995 for finding a cavalcade number of genes responsible for correctly building a fruit fly embryo by studying an enormous number of maggots. It’s these two that we can thank for popularising weird and wonderful gene names, as they named the genes after the effect that mutations had upon the embryos. Initially many of these were German words like Knirps, meaning ‘little one’, Spaetzle - a type of stodgy dumpling, and Krueppel, meaning cripple.
But the ‘fly pushers’ as Drosophilist’s are affectionately known, have really run with it - Hedgehog, Groucho, Kate Moss, Swiss Cheese, Ken and Barbie, and my personal favourite - Mothers Against Decapentaplegic, which sounds more like a heavy metal band than a gene. Drosophila Melanogaster, we salute you.
References and further reading
Stephenson, R., & Metcalfe, N. (2013). Drosophila melanogaster: a fly through its history and current use. The Journal of the Royal College of Physicians of Edinburgh, 43(1), 70–75. doi:10.4997/jrcpe.2013.116
Picture credit: Sanjay Acharya via Wikimedia Commons, CC-BY-SA 4.0
