Drosophila melanogaster (the common fruit fly)
Drosophila has a genome that is slightly larger than that of C. elegans but is still quite small at only 4 chromosome pairs and 1.6x108 base pairs. Its life cycle takes 10 days. The larva hatches 22 hours after fertilization. The entire genome has been sequenced and is available at http://www.fruitfly.org.
As shown in the figure below, Drosophila embryos have 3 thoracic and 8 abdominal segments, allowing easy identifications of body plan mutants.
- Halteres. Balancers which form in third thoracic segment.
- Wings. Normally form in second thoracic segment. Wild type have only two wings, making Drosophila dipterans.
- Bicoid. Contains homebox.
- Even-skipped. Contains homeobox.
- Engrailed. Contains homeobox.