Drosophila melanogaster

Use in genetic research[edit]
Drosophila is considered one of the most valuable genetic model organisms; both adults and embryos are experimental models.^[46] Drosophila is a prime candidate for genetic research because the relationship between human and fruit fly genes is very close.^[47] Human and fruit fly genes are so similar, that disease-producing genes in humans can be linked to those in flies. The fly has approximately 15,500 genes on its four chromosomes, whereas humans have about 22,000 genes among their 23 chromosomes. Thus the density of genes per chromosome in Drosophila is higher than the human genome.^[48] Low and manageable number of chromosomes make Drosophila species easier to study. These flies also carry genetic information and pass down traits throughout generations, much like their human counterparts.^{[clarification needed]} The traits can then be studied through different Drosophila lineages and the findings can be applied to deduce genetic trends in humans. Research conducted on Drosophila help determine the ground rules for transmission of genes in many organisms.^[49][4] Drosophila is a useful in vivo tool to analyze Alzheimer's disease.^[50] Rhomboid proteases were first detected in Drosophila but then found to be highly conserved across eukaryotes, mitochondria, and bacteria.^[51][52] Melanin's ability to protect DNA against ionizing radiation has been most extensively demonstrated in Drosophila, including in the formative study by Hopwood et al 1985.^[53]
Microbiome[edit]
Like other animals, Drosophila is associated with various bacteria in its gut. The fly gut microbiota or microbiome seems to have a central influence on Drosophila fitness and life history characteristics. The microbiota in the gut of Drosophila represents an active current research field.
Drosophila species also harbour vertically transmitted endosymbionts, such as Wolbachia and Spiroplasma. These endosymbionts can act as reproductive manipulators, such as cytoplasmic incompatibility induced by Wolbachia or male-killing induced by the D. melanogaster Spiroplasma poulsonii (named MSRO). The male-killing factor of the D. melanogaster MSRO strain was discovered in 2018, solving a decades-old mystery of the cause of male-killing. This represents the first bacterial factor that affects eukaryotic cells in a sex-specific fashion, and is the first mechanism identified for male-killing phenotypes.^[54] Alternatively, they may protect theirs hosts from infection. Drosophila Wolbachia can reduce viral loads upon infection, and is explored as a mechanism of controlling viral diseases (e.g. Dengue fever) by transferring these Wolbachia to disease-vector mosquitoes.^[55] The S. poulsonii strain of Drosophila neotestacea protects its host from parasitic wasps and nematodes using toxins that preferentially attack the parasites instead of the host.^[56][57][58]
Since the Drosophila species is one of the most used model organisms, it was vastly used in genetics. However, the effect abiotic factors,^[59] such as temperature, has on the microbiome on Drosophila species has recently been of great interest. Certain variations in temperature have an impact on the microbiome. It was observed that higher temperatures (31 °C) lead to an increase of Acetobacter populations in the gut microbiome of Drosophila melanogaster as compared to lower temperatures (13 °C). In low temperatures (13 °C), the flies were more cold resistant and also had the highest concentration of Wolbachia.^[60]
The microbiome in the gut can also be transplanted among organisms. It was found that Drosophila melanogaster became more cold-tolerant when the gut microbiota from Drosophila melanogaster that were reared at low temperatures. This depicted that the gut microbiome is correlated to physiological processes.^[61]
Moreover, the microbiome plays a role in aggression, immunity, egg-laying preferences, locomotion and metabolism. As for aggression, it plays a role to a certain degree during courtship. It was observed that germ-free flies were not as competitive compared to the wild-type males. Microbiome of the Drosophila species is also known to promote aggression by octopamine OA signalling. The microbiome has been shown to impact these fruit flies' social interactions, specifically aggressive behaviour that is seen during courtship and mating.^[62]