Drosophila melanogaster

Within a few years of the rediscovery of Mendel's rules in 1900, Drosophila melanogaster (the so-called fruit fly) became a favorite "model" organism for genetics research.

Some of the reasons for its popularity:

  • The flies are small and easily reared in the laboratory.
  • They have a short life cycle The figure shows the various stages of the life cycle (not all drawn to the same scale). A new generation of adult flies can be produced every two weeks.
  • They are fecund; a female may lay hundreds of fertilized eggs during her brief life span. The resulting large populations make statistical analysis easy and reliable.
  • The giant ("polytene") chromosomes in the salivary (and other) glands of the mature larvae.
    • These chromosomes show far more structural detail than do normal chromosomes, and
    • they are present during interphase when chromosomes are normally invisible.

More recently, Drosophila has proven in other ways to have been a happy choice.

  • Its embryo grows outside the body and can easily be studied at every stage of development.
  • The blastoderm stage of the embryo is a syncytium (thousands of nuclei unconfined by cells) so that, for example, macromolecules like DNA injected into the embryo have easy access to all the nuclei.
  • The genome is relatively small for an animal (less than a tenth that of humans and mice). [View]
  • Mutations can targeted to specific genes. [Link to discussion of transposons.]
Chromosomes of Drosophila melanogaster as they appear at metaphase of mitosis. Both sexes have three homologous pairs of autosomes. In addition, the females have two X chromosomes (left), and the males have an X and a Y chromosome (right); these are the sex chromosomes.

Follow these links to examples of things that Drosophila has taught us.

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17 April 2014