artwork by Molly Fischer
Molly has decided to share more of her art! I told her I’d take anything I can get and build a post around it. Her newest subject is insect wings, butterfly and dragonfly. I love the detail in her work – much more flair than I have the time or the ability to do.
At first glance, this one seems tricky – what do insect wings have to do with the human genome? Actually, a particular set of insect wings lead to the discovery of this week’s gene of interest: NOTCH1.
Back in the 1910’s, Columbia University had a room that was filled with flies [1]. A few would buzz around rotten bananas hanging from the ceiling, but most were kept in milk bottles with their newly hatched grubs. Professor Thomas Hunt Morgan established the ‘fly room’ in 1911 to study the chromosomal theory of heredity – the theory that chromosomes are responsible for passing traits from parent to offspring. He chose fruit flies (drosophila melanogaster) because they breed quickly (a new generation each week), they’re cheap to maintain, and they’re small, but not so small that you need a microscope to see them [2]
Morgan would expose the flies to mutagens and check each generation for mutations, noting how those traits passed down from generation to generation. Some developed odd eye color or legs where their antennae should be. Genes were named after these striking mutations. For example, the gene sonic hedgehog was, in part, named after a mutant fly covered in small pointy projections resembling the quills of a hedgehog [3].
One set of flies developed oddly shaped wings. Under the microscope, one of Morgan’s students noticed notches at the ends of each wing. They named this mutation (and later it’s associated gene) NOTCH [4].
NOTCH is a cell-cell receptor, which means it sits on the surface of the cell (like other cell receptors we’ve discussed), but instead of interacting with a free-floating growth factor or hormone, it connects to proteins found on the surface of another cell. Humans have four NOTCH genes. All four associated receptors control cell growth and are therefore important regulators of shape. In blood vessels, NOTCH receptors regulate cell growth to control vessel diameter and branching [5]. That’s likely why a few of the veins in the notched wings are a little thicker than normal.
The ‘fly room’ uncovered many genes that are important in humans and flies alike, earning Morgan and his team a Nobel Prize in 1933 [2]. More than 0ne hundred years later, fruit flies and their mutants are still an important scientific model organism. With thousands of mutations, and more still being generated, you’d think by now one of the mutant flies would have super powers.
References
[1] “Columbia University Fly Room”. Nature.com. 2014.
[2] “Thomas H. Morgan – Biographical”. NobelPrize.org. 7 Feb 2016.
[3] Nüsslein-Volhard, C.; Wieschaus, E. (1980). “Mutations affecting segment number and polarity in Drosophila”. Nature 287 (5785): 795–801. PMID 6776413
[4] de Celis, J.F.; Garcia-Bellido, A. (1994). “Roles of the Notch gene in Drosophila wing morphogenesis”. Mech Dev 46 (2): 109-22. PMID 7918096
[5] Siekmann, A.F.; Lawson, N.D. (2007) “Notch signalling limits angiogenic cell behaviour in developing zebrafish arteries” Nature 445 (7129): 781-4. PMID 17259972
Gene of Interest 