The fly saga: How Drosophila became the queen of genetics

By Nikhil Srivastava

              “They [the flies] will fool you every time.” Thomas Hunt Morgan to A.H. Sturtevant

I am sure you all must have heard about Marie Kondo through a very popular and recent web series, she is a Japanese organizing consultant who uses a special type of tidying method for cleaning and organizing cluttered houses.  Kondo’s name has been used by a group of scientists from the United States and Canada to name a recently discovered protein in Drosophila melanogaster which plays a very similar role in its embryonic development as Kondo plays in real life. The Marie Kondo protein, which is a part of ubiquitin-proteasome system and works as an E2 ubiquitin enzyme, has a role of clearing up three maternally derived proteins during maternal-to-zygotic transition (MZT). But this story which I am narrating is not about the Marie Kondo protein, it is about Drosophila or the fruit flies in which this important discovery was made. The importance and use of the Drosophila sp. as an animal model has revolutionized the field of genetics and molecular biology. In 1909, T.H. Morgan used the fruit flies for the first time in his laboratory. Since that day many milestone discoveries have been made in the field, I am going to enumerate some of these in this article.

1. The fly mutants
One of the main reasons why Morgan chose flies for the genetic studies was the high number of phenotypic mutations naturally prevalent in them, and also the ease of introducing novel mutations by various methods of mutagenesis. These have led to the discovery of many genes in developmental signaling pathways, human diseases, nervous system functioning and many more. In 2015, Yamamoto et al. used Drosophila X-chromosome to identify 165 new genes which were required for the development, function and maintenance of the nervous system.

2. P-elements
These are the transposable elements discovered in Drosophila in 1960’s and have been extensively used as vectors of gene transfer and to study the mechanisms of eukaryotic cut-and-paste transposition. In flies, this transposon causes a bizarre genetic trait known as hybrid dysgenesis. Transposable elements invade other genes as mobile elements, but P-elements invaded molecular genetics as an important and much needed genetic tool.

3. Homeotic genes
The discovery of Hox genes marks the beginning of one of the most interesting eras for genetics. The first-ever discovery of two types of homeotic mutations in Drosophila melanogaster were bizarre ones which caused the antennae of the fly to develop into legs. This group of genes later came to be popularized as ‘the master regulator of development’, which helps in proper patterning of the tissues and organs of different organisms.

4. Circadian rhythms
Discovery of per (period) gene in flies by Benzer in 1971 is an essential and foundational work to study the molecular mechanisms corresponding circadian rhythms whose discovery took 13 long years to identify this gene in lack of recombinant DNA technology. Today we know about a homologue of this gene called PER2, mutation of the gene causes familial advanced sleep phase syndrome in humans.

5. Notch signaling pathway
Mutations in Notch signaling pathway was first identified in 1915 which caused malformation in wings in D. melanogaster.  Notch pathway is conserved amongst most of the animals and plays a significant role in their developmental pathways such as gametogenesis and cell proliferation.

Michael Young, Nobel Laureate for the year 2017 in physiology and medicine, expressed his gratitude towards his oldest colleague – Drosophila. Crucial research about various complex mechanisms in life sciences is owed to this magnificent invertebrate. More than 1500 species of this insect are like a huge gold mine to science, only part of which has been excavated!

About the author

Nikhil Srivastava is a final year master’s student at the Department of Zoology of Banaras Hindu University (India) with specialization in molecular and human genetics. He was a Khorana Scholar at the Ohio State University, Ohio, USA in 2019. His research interests are in diverse fields of molecular biology and genetics. He is excited about understanding the complex synchronization between the genome of an organism and the elements of Mother Nature at the molecular level that happens to form life. He is also interested about the genetics at the population level. He is influenced both by literature and science, and that is visible in his style of writing.


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