Flies, and particularly Drosophila, have played and play an extraordinary role in scientific discovery, in medicine and in nature.
A place in scientific research
- Thomas H. Morgan used Drosophila to demonstrate, in 1910, that heredity is linked to sexual reproduction, and in 1916, together with his student C.B. Bridges, they demonstrated that genes reside in chromosomes.
- First model system with a genetic combinatorial system (with the binary gene regulatory system UAS / GAL4) for ectopically expressing genes of interest in cells of interest.
- Fly was the organism in which single genes (e.g. hox genes) were demonstrated to have the power to induce developmental transformations, which revolutionized the field of developmental biology.
- A hierarchy of genes controlling the partitioning of the embryo during development was discovered in Drosophila.
- The use of transposons--mobile genetic elements that can hop around different places in the chromosome--was used in Drosophila to discover the genes underlying induced mutations. This discovery was but the start of what made Drosophila an extraordinary model system with a strong genetic toolkit for the manipulation and monitoring of its cells and tissues.
- The neurogenic genes that control epidermal versus neuronal cell fate (notch, neuralized, delta, mastermind, big brain and enhancer of split) were discovered in Drosophila.
- Balancer chromosomes, a useful technique for stabilizing a specific set of genes in a population, were first established in Drosophila. Still today, balancer chromosomes is what sets Drosophila apart as a model system, providing inexpensive means to maintain a population of transgenic animals over time.
- The discovery of genes for potassium channels (like shaker) was done in Drosophila.
- The discovery of the TRP genes (transient receptor potential), which encode proteins that are ion channels gated by specific cues, either ligands or temperature or light, was done first in Drosophila.
- The discovery of genes for regulating and establishing circadian rhythms was done first in Drosophila.
- It was first shown in Drosophila that apoptotic cells emit molecular signals that stimulate stem cells to proliferate, initiating the regeneration of wounded tissue.
See also these reviews on the role of Drosophila in genetics and neuroscience research.
A place in nature
- Flies pollinate numerous plants. For example Drosophila pollinates some orchids.
- Flies and other insects are a source of protein (in the form of larvae) for animals that eat fruit (DeFoliart, 1989). There is a hypothesis postulating that primate color vision evolved to identify colored fruit, to select the most ripe and therefore not only the most sugar-rich but also the most likely to contain caterpillars, which are an excellent source of fat and protein. This kind of energy- and nutrient-dense food (as opposed to e.g. grass) enables eating comparatively little amounts of food with relatively blunt and small teeth, therefore enabling populations of animals to evolve towards less time dedicated to foraging and more to leisure and creative activities. In other words, caterpillars might have been one of the few factors enabling primates to grow large brains.
A place in medicine
- About 75% of known human disease genes have a recognizable match in the genome of Drosophila, enabling experimentation with these genes in mere weeks as opposed to the months or years required for genetic experiments in mouse or zebrafish.
- Imaginal disks--the tissue blobs within a fly embryo and larva that will give rise to tissues of the adult fly--are used as a model to study tissue regeneration.
- Fly larvae--maggots--are used successfully for the treatment of gangrene: the larvae eat the rotten parts, leaving the living flesh untouched. This feat has been named "biosurgery".
- Flies, or rather their eggs and larvae, infest a cadaver at specific times after death, therefore enabling the determination of the approximate time of death in the field of forensics.
See also this excellent review enumerating the many uses of Drosophila in biology and medicine, some resulting in Nobel prizes.