Drosophila Life Cycle and its contribution to genetic research

1. Drosophila melanogaster
2/15/2024 Dr. Mukesh Tanwar

2. • The genus Drosophila (from the Greek words meaning “lover
of dew”) comprises a large number of species, the most
intensively studied being D. melanogaster
• They belong to the family Drosophilidae, whose members
are often called “fruitflies”.
• This species was described in the middle of the nineteenth
century under the name D. ampelophilia, a name meaning
“lover of grape vines.”
• After being established as an experimental animal, D.
ampelophilia was renamed D. melanogaster, which means
“black belly.”
Drosophila
2/15/2024 Dr. Mukesh Tanwar

3. 2/15/2024 Dr. Mukesh Tanwar
C. W. Woodworth seems to have been the first person to culture
Drosophila in the laboratory.
It is from Woodworth that W. E. Castle, a professor of zoology at
Harvard University, learned of the advantages of using this animal as an
experimental organism.
Castle then recommended it to T. H. Morgan, who began to culture
Drosophila in 1909
From its intensive work with Drosophila, Morgan’s laboratory at
Columbia University became known as “The Fly Room”.
Numerous students worked in this laboratory from 1910 until 1926, the
year Morgan moved his research to the California Institute of
Technology.

4. 2/15/2024 Dr. Mukesh Tanwar
 The most famous of Morgan’s students were Calvin Bridges, Alfred
Sturtevant, and Hermann Muller.
 Bridges provided the proof for the Chromosome Theory of
Heredity
 Sturtevant produced the world’s first chromosome map.
 Muller discovered that mutations could be induced by X-ray
irradiation.
 Since the days of the Fly Room, research on Drosophila has grown
into a worldwide endeavor. Hundreds of different laboratories are
currently investigating the genes and chromosomes of this animal

5. Fruit flies are handy with simple food requirements and occupy little
space.
The reproductive cycle is complete in about 12 days at room
temperature, allowing quick analysis of test crosses.
Fruit flies produce large numbers of offspring to allow sufficient data to
be collected. Examination and data collection is easy because the flies
can be quickly and easily immobilized for examination.
Many types of hereditary variations can be recognized with low-power
magnification.
Drosophila has a small number of chromosomes (four pairs), a genome
size smaller than the human complement of 23 pairs of chromosomes.
The giant (“polytene”) chromosomes in the salivary glands of the
mature larvae.
Advantages of Drosophila as a model organism
2/15/2024 Dr. Mukesh Tanwar

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https://i.stack.imgur.com/2raaO.png

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https://4.bp.blogspot.com/-
CVqhheB0ITA/UENEfs22rCI/AAAAAAAAA2o/jXV0skJwN74/s320/polytene+chromosome.jpg

8. Image Link: https://www.flickr.com/photos/11304375@N07/2993343506
2/15/2024 Dr. Mukesh Tanwar

9. A large number of genetically defined mutants are available which
define most aspects of the fly’s biology.
2/15/2024 Dr. Mukesh Tanwar

10. Many Drosophila genes are homologous to human genes. Eg. Pax6
Much research about the genetics of Drosophila over the last 50 years
has resulted in a wealth of reference literature and knowledge about
hundreds of its genes.
The genome is relatively small for an organism (less than a tenth that of
humans and mice).
2/15/2024 Dr. Mukesh Tanwar

11. Image Source: https://www.flickr.com/photos/diluvienne/6813119839/
2/15/2024 Dr. Mukesh Tanwar

12. Phenotypic Differences between Male and Female Fly
Image Source: https://arrogantscientist.wordpress.com/2009/03/06/the-differences-between-the-sexes/
Size
Sex Combs in male
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13. Markings on the abdomen
Alternating dark and light bands can be seen on the entire rear portion of the
female but in male last three segments looks like fused segments
https://www.carlsonstockart.com/photo/fruit-fly-drosophila-male-female-illustration/
2/15/2024 Dr. Mukesh Tanwar

14. External genitalia on abdomen
Located at the tip of the abdomen,
• The ovipositor of the female is pointed.
• The claspers of the male are darkly pigmented, arranged in
circular form, and located just ventral to the tip.
2/15/2024 Dr. Mukesh Tanwar

15. Phenotypic Differences between Male and Female Fly
Image Source: https://commons.wikimedia.org/wiki/File:Drosophila_suzukii_smulans2.jpg
2/15/2024 Dr. Mukesh Tanwar

16. Phenotypic Differences between Male and Female Fly
Image Source: https://commons.wikimedia.org/wiki/File:Drosophila_suzukii_smulans2.jpg
2/15/2024 Dr. Mukesh Tanwar

17. Shape of abdomen
The tip of the abdomen
 elongated in the female
 more rounded in the male.
https://commons.wikimedia.org/wiki/File:Biology_Illustration_Animals_Ins
ects_Drosophila_melanogaster.svg
2/15/2024 Dr. Mukesh Tanwar

18. https://commons.wikimedia.org/wiki/File:Critique_of_the_Theory_of_Evolution_Fig_004.jpg
http://www.mun.ca/biology/scarr/4241_Devo_DrosophilaSex.html
2/15/2024 Dr. Mukesh Tanwar

19. Life Cycle of Drosophila
https://www.flickr.com/photos/11304375@N07/2993342324
2 Days
5 Days
2/15/2024 Dr. Mukesh Tanwar

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Drosophila contribution to the Science of
Genetics

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23. 1933: Thomas Hunt Morgan – The role played by
chromosomes in heredity
1946: Hermann Joseph Muller – The production of mutations
by means of X-ray irradiation
1995: Edward B. Lewis, Christiane Nüsslein-Volhard, Eric F.
Wieschaus – The genetic control of early embryonic
development
2004 : Richard Axel – Odour receptors and the organisation
of the olfactory system (mainly rodent work)
2011: Jules A. Hoffmann – The activation of innate immunity
2017: Jeffrey C. Hall, Michael Rosbash, Michael W. Young –
molecular mechanisms controlling the circadian rhythm
Source: https://droso4schools.wordpress.com/why-fly/
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To be continued ………