Scientists are investigating the genetic system of the Drosophila fruit fly to discover how humans perceive the world and make choices
For almost a century, scientists have used the fruit fly (scientifically known as Drosophila melanogaster) as a model organism for investigating various biological systems. Today it remains the most studied organism in biological research.
The fruit fly's robust genetic system makes it an invaluable tool for scientists studying inheritance. Drosophila is being used as a genetic model for several human diseases, including neurodegenerative disorders such as Alzheimer's, Parkinson's and Huntington's disease. Researchers are also using the fly to study mechanisms underlying ageing, immunity, diabetes, and cancer.
Other scientists are using the fruit fly to test some basic ideas about how we - and other animals - see the world around us. Visual information is clearly important for many organisms. An animal's visual system is what allows it to see, by interpreting the information from light to build up a representation of the world surrounding its body.
Whilst researchers know the functional architecture of the brain and eye of the Drosophila in great detail, they don't know much about the route that the visual information takes, and how it's processed in the nervous system. By using electrophysiological and imaging experiments, scientists can learn a lot about how individual neurons - or groups of neurons - process visual signals. But it's only through experiments studying the behaviour of flies that hypotheses about visual processes can be proved or abandoned.
Why use Drosophila?
Drosophila (pictured) is a small fly about 3mm long that lives for only around two weeks. Researchers can speed up or slow down their life cycle, by varying the temperature they are kept in. Fruit flies are also cheap, and easy to keep in large numbers. They are easy to handle, are well-understood and their entire genome has recently been sequenced (completed in 2000).
Scientists can also study mutant flies, with defects in any of several thousand genes. A mutant fly is one that has a change in the sequence of the nucleotides in the DNA of a particular gene, which could mean that it can't produce a particular enzyme or protein properly. By using Drosophila mutants, scientists can look at the role of a specific part of a cascade or pathway in the fly.
Similarly, scientists can increase the number of enzymes or proteins in the fly to investigate its effect. They can compare a mutant fly with a missing enzyme to a normal fly, and thus shed light on the function of that missing enzyme.
The Drosophila has a big advantage over human genetic material, as it has only four pairs of chromosomes, compared to humans who have 23 pairs - so there is less genetic information for researchers to deal with. Scientists can effectively breed the flies to contain the genes or mutant genes they require, to study anything from very precise mechanisms to general behavioral responses.
The Drosophila genome shares many similarities to the human genome. Of 289 genes known to cause disease in humans - including cancer, neurodegenerative and cardiovascular diseases - researchers discovered about 175 in Drosophila.
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