A four-chromosome fly became genetics’ favorite animal
Drosophila melanogaster—the common fruit or vinegar fly—draws researchers for a short life cycle, four chromosome pairs, and huge broods. Charles W. Woodworth proposed it as a model in 1901; in 1946 it became the first animal launched into space.
Originally African, non-African lineages share one expansion origin. Brick-red compound eyes, yellow-brown bodies, and black abdominal rings mark wild type. Confusingly, Tephritidae “fruit flies” such as Ceratitis capitata are different pests. The name means dew-loving black-belly in Greek roots. It thrives around rotting fruit and fermenting drinks, turning up in orchards, kitchens and pubs on every continent. By 2017 six Nobel Prizes had gone to scientists working with it. The Tephritid mix-up matters most in the Mediterranean, Australia and South Africa.
A round head packed with ommatidia, a thorax with three leg pairs and ~4 mm clear wings, plus balancing halteres, make a compact flight machine. Labs exploit mutants to map genes, development, infection, and behavior. The red of the eyes comes from two pigments, brown xanthommatin made from tryptophan and red drosopterins made from GTP. Females run about 2.5 millimetres and can be up to 30 percent bigger than males, and the fly's sex and appearance are set purely by genes, not hormones.
Speed is its gift to science. At 25 °C a fly lives about 50 days, and development from egg to adult takes eight and a half days, shrinking to seven at 28 °C but stretching past 50 days at 12 °C. Eggs half a millimetre long hatch within 15 hours, and the larvae moult twice while feeding on microbes that break down fruit. Courting males sing by vibrating one wing, then tap and lick before attempting to mate; females can refuse by walking off, kicking or extending the ovipositor. Mating lasts 15 to 20 minutes, and the sperm cells are 1.76 millimetres long, a startling length for an insect of about two and a half millimetres.
Source: Drosophila melanogaster
