The fragile head and brain of a fly are not easy things to examine but MRC scientists have figured out how to make it a little simpler. And they hope their research will shed light on human disease.
Using an imaging technique, originally developed at the MRC Human Genetics Unit, called optical projection tomography (OPT) they have generated startling 3D images of the inside of a fruit fly for the first time. The OPT images could help to speed up genetic research into Alzheimer’s and other human diseases that affect 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 they die.’’
Because the fruit fly (Drosophila melanogaster) and human share many genes with similar functions, the fly is widely used by genetic researchers to study how genes influence human disease.
‘‘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.
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, the team describes 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, as they are known, 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 conditions too.’’
Source: Public Library of Science
Related stories:
Model for angelman syndrome developed
A model for studying the genetics of Angelman syndrome, a neurological disorder that causes mental retardation and other symptoms in one out of 15,000 births, has been developed by biologists at The University of Texas at Austin.
A new light on the brains of people with borderline personality disorder
In a game of give and get, the brains of people with borderline personality disorder often don't get it.
Tuning in to a new language on the fly: Effects of context and seasonality on songbird brain
Research conducted at Rutgers University has shown that exposure to a changed acoustic and social environment can rewire the way the brain processes sounds. Beginning in the cochlea of the inner ear, nerve cells of the auditory system parse incoming sounds into their different components. Study of the responses of individual brain cells has shown that they respond best to a particular frequency (pitch) of sound, less well to nearby frequencies, and poorly to distant sound frequencies. The range of effective frequencies can be measured as the "tuning width." Cells with similar tuning are found together, producing an orderly map of all the possible frequencies spread out across the auditory part of the brain.
Brain tweak lets sleep-deprived flies stay sharp
Staying awake slows down our brains, scientists have long recognized. Mental performance is at its peak after sleep but inevitably trends downward throughout the day, and sleep deprivation only worsens these effects.
Searching for shut eye: Study identifies possible sleep gene
While scientists and physicians know what happens if you don't get six to eight hours of shut-eye a night, investigators have long been puzzled about what controls the actual need for sleep. Researchers at the University of Pennsylvania School of Medicine might have an answer, at least in fruit flies. In a recent study of fruit flies, they identified a gene that controls sleep.
One missing gene leads to fruitless mating rituals
Male fruit flies missing a gene for one particular odor receptor become clueless in matters of love, scientists at Duke University Medical Center have discovered.
It takes nerves for flies to keep a level head
The nerve connections that keep a fly's gaze stable during complex aerial manoeuvres, enabling it to respond quickly to obstacles in its flight path, are revealed in new detail in research published today (22 July 2008).
Probing Question: Fishhooks of addiction
When the American writer Theodore Roethke taught at Penn State from 1936 to 1943, he was known for three things: being a good poet, coaching the men’s tennis team, and falling down drunk, perhaps the latter more than the former. Roethke, a brilliant and tortured man, knew well the seduction of drink and the agony of addiction. In his poem “Journey Into the Interior,” Roethke writes, “In the long journey out of the self, / There are many detours, washed-out interrupted raw places / Where the shale slides dangerously / And the back wheels hang almost over the edge / At the sudden veering, the moment of turning.”