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Image of the Week: Drosophila melanogaster

2 May, 2014

Drosophila melanogaster


In the next few weeks we will be shining the spotlight on some of the model organisms that have helped us to gain a better understanding of genetics and the way gene interactions make us who we are.

This week Deborah-Fay Ndhlovu looks at the humble fruit fly, Drosophila melanogaster, to find out what flies have to do with human health.

It is said that a picture is worth a thousand words, but sometimes there is more than meets the eye. This image gives us a close-up look at an eye of Drosophila melanogaster, more commonly known as a fruit fly. Colour has been added to the scanning electron micrograph of the eye to show the natural colours.

It’s a striking image, but it doesn’t reveal just how important these tiny flies are in genetics and developmental biology. Drosophila have been used as model organisms for over 90 years and their short lifecycle of around two weeks allows multiple generations to be studied within months.

It is the first complex organism to have its genome sequenced. This was done by the US-based Drosophila Genome Project Group, which sequenced 99 per cent of the 13,600 genes of the fruit fly in the year 2000. Although the number of fruit fly genes is much smaller than that found in humans (currently estimated to be around 20,000), some of its genes are homologous to human disease genes.

Ten per cent of these genes are involved in neurodegenerative diseases, which means that these flies can be used as a genetic model for Parkinson’s and Alzheimer’s. The fruit fly response to the drugs for the central nervous system is similar to that in humans, although metabolic differences between flies and humans, mean that some drugs may be more toxic to fruit flies. Despite this, fruit flies are useful in the drug development process.

Often the fruit fly is used as a screening platform to narrow down a large pool of potential drug candidates to a smaller one whose efficacy is then tested in mammalian models.

Wellcome Images is one of the world’s richest and most unusual collections, with themes ranging from medical and social history to contemporary healthcare and biomedical science. Over 100,000 high resolution images from our historical collections are now free to use under the Creative Commons-Attribution only (CC-BY) licence.

Edited on 2nd May to amend the number of human genes. Although it was estimated that we had 80,000-100,000, work done on the Human Genome Project has led to the revision of this number.


3 Comments leave one →
  1. almostnospecifics permalink
    2 May, 2014 8:13 am

    Hi, loved your link with the saying and the image, but you mention that Humans have 100,000 genes. This is an old fashioned belief and the true number is in fact, and really interestingly, much lower – around 20k. This was discovered after the early analysis from the human genome project. Now the fascinating research is on not what genes you have but how the various levels their expression is controlled.

    I notice that the science museum’s website states this number and Google detects 100,000 from many other results. Oh dear.

  2. Paul Driscoll permalink
    2 May, 2014 10:18 am

    Humans do not have 80,000-100,000 genes. Maybe people once thought so, but the HGP (now long ago) came in with a much lower count.

  3. 10 May, 2014 8:53 pm

    Actually C. elegans was the first complex (multicellular) organism to have its genome sequenced in 1998. D. melanogaster was the first multicellular organism to have its genome sequenced by the whole genome shotgun sequencing method, which was a major technical breakthrough that ushered in the modern era of whole genome sequencing.

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