Fruit fly discovery provides insights into brain stem cell development

15 December 2014

Drosophila melanogaster (fruit fly) visual system.

Image: Drosophila melanogaster (fruit fly) visual system. The scientists discovered a new method of neuron production in the region adjacent to the lobula plate (arrows) that has similarities with the mechanisms observed in the mammalian brain.

New research by a team at the Medical Research Council's National Institute for Medical Research (NIMR; now part of the Francis Crick Institute) explores the mechanisms by which neural stem cells are generated and produce their offspring. Neural stem cells are a type of brain cell that continuously divides and produces new and different nerve cells, or neurons. 

Animal brains are organised into different areas with distinct functions, each made up of many diverse types of neurons. Scientists had shown that this diversity is caused by patterning of neural stem cells in different parts of the brain, but did not know whether other mechanisms also could contribute. 

Now, Holger Apitz and Iris Salecker of NIMR have identified a new strategy for generating neurons in the brains of the fruit fly Drosophila. 

They studied the fly's visual system. It was already known that - as in many other parts of the fly brain - neurons are typically produced by cells called neuroblasts, the fly equivalents of neural stem cells. When these divide, each neuroblast produces one new copy of itself and one other cell that divides to generate neurons. 

However, the scientists identified one region in the fly's visual system that uses a different strategy to generate its neural stem cells and neurons. This involves the production of precursor cells that move from one region to another before developing into neural stem cells and giving rise to neurons. This strategy is remarkably similar to a process observed in the mammalian brain, and therefore may also occur in humans. 

The scientists' discovery means that future studies will be able to use this region of the Drosophila brain as a model to understand what happens in mammalian brains. In the long term, this could help to find out what may go wrong in brain disorders caused by developmental defects and to work towards ways to treat such defects. 

Dr Salecker said: "Since some of the observed molecular and cellular mechanisms appear to be shared between the fly visual system and mammalian brains, we hope that our findings, in conjunction with the powerful genetic toolbox of Drosophila, can be used as a start to systematically identify the genes controlling the production of neural stem cells and neurons by this particular developmental strategy in the future". 

The paper, A region-specific neurogenesis mode requires migratory progenitors in the Drosophila visual system, is published in Nature Neuroscience.

  • Scientists at the Medical Research Council's National Institute for Medical Research have discovered a previously unrecognised strategy of producing neurons in the brains of the fruit fly Drosophila melanogaster. This strategy shares similarities with processes found in the mammalian brain, thus opening up possibilities for future studies identifying new genes controlling these developmental steps.
  • Fruit flies have been studied for over a century by developmental biologists and geneticists. Because it is so well studied and we know so much about its genes and biological processes, Drosophila is a powerful model for investigating what happens during the development of animals, including humans, and what might cause disorders.