Fruit fly imaging aids research into Alzheimer's
18 September 2007
Scientists at the UK Medical Research Council (MRC)
have developed optical imaging technology that can generate 3D internal
images of the fruit fly for the first time. Using an imaging technique
called optical projection tomography (OPT), which was originally developed
at the MRC Human Genetics Unit, they have generated startling 3D images of
the inside of a fruit fly.
Due to the similarity between human and fly genes, the technique could
help to speed up genetic research into Alzheimer’s and other human diseases
that affect brain cells.
3D images of a fruit fly generated using optical projection
tomography generated after first bleaching the fly’s exoskeleton. Different
organs can be clearly seen. The images mean scientists no longer have to
dissect the flies by hand to observe how genetic changes influence the loss
of brain cells.
Dr Mary O’Connell of the MRC Human Genetics Unit
who led the research explained: ‘‘Neurodegeneration, the gradual loss of
function of brain cells that occurs in Alzheimer’s, Parkinson’s and motor
neurone diseases, isn’t a strictly human phenomenon. Insects are affected by
it too. In the autumn, bees and wasps often develop erratic behaviour before
"It’s already known that defects in the equivalent fly genes
involved in human brain diseases cause brain cells in fruit flies to lose
function as they age,’’ Dr O’Connell continued.
Because the fruit fly (Drosophila melanogaster) and humans share
many genes with similar functions, the fly is widely used by genetic
researchers to study how genes influence human disease.
OPT could help researchers to look at how the fly brain changes in
response to alterations in the normal activity of a specific gene without
the risk of damaging tissue through dissection.
In a paper published in the September 5 issue of the online, open-access
journal PLoS ONE (1), the researchers describe how they
have already used the technique to image individual cavities within the
brain of an ageing fly and see the brain deteriorate.
MRC PhD student Leeanne McGurk who captured many of the OPT images
explained why the technique works: ‘‘The dark colour of the fly exoskeleton
prevents us from seeing inside it using a standard light microscope. In the
past this has meant scientists have had to tease apart fruit fly tissues by
hand — a laborious process. Now, we have got over the problem by bleaching
the fly exoskeleton. When the fruit fly becomes colourless it is possible to
use imaging techniques not only to view its internal organs but to generate
2D and 3D images of the entire fly. ’’
Using OPT images in this way will
allow scientists to visualise where and how the products of selected genes
are present in the fly. These patterns of gene expression, will help to
identify genes that control parts of the central nervous system and so
provide detailed information about the human brain.
Bleaching of the exoskeleton to clear away the colour also allows images
to be generated using other microscopic techniques that depend on
penetration of light.
Dr O’Connell concluded: ‘‘This research is not simply limited to the
study of conditions like Alzheimer’s but can also be used to study fly
anatomy. The shape and size of organs can be affected by diseases like
diabetes so imaging may yield clues to further our understanding of other
1. McGurk L, Morrison
H, Keegan LP, Sharpe J, O’Connell MA (2007) Three-Dimensional Imaging of
Drosophila melanogaster. PLoS ONE 2(9):e834.
The paper is available at:
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