Drosophila innubila | |
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A Drosophila innubila female on mushroom | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Diptera |
Family: | Drosophilidae |
Genus: | Drosophila |
Subgenus: | Drosophila |
Species: | D. innubila |
Binomial name | |
Drosophila innubila Spencer in Patterson, 1943 | |
Drosophila innubila is a species of vinegar fly restricted to high-elevation woodlands in the mountains of the southern USA and Mexico, [1] which it likely colonized during the last glacial period. [2] Drosophila innubila is a kind of mushroom-breeding Drosophila, and member of the Drosophila quinaria species group. Drosophila innubila is best known for its association with a strain of male-killing Wolbachia bacteria. These bacteria are parasitic, as they drain resources from the host and cause half the infected female's eggs to abort. However Wolbachia may offer benefits to the fly's fitness in certain circumstances. [3] The D. innubila genome was sequenced in 2019. [4] [5]
Drosophila innubila is stably infected by a strain of male-killing Wolbachia bacteria. The association between Drosophila innubila and Wolbachia can vary greatly within local populations. However, their relationship is very consistent across the overall Drosophila innubila species. [3]
Male-killing by these Wolbachia results in the offspring of flies being entirely female, the biological sex with the higher reproductive output. Thus, this Wolbachia spreads in the population owing to the increased reproductive advantage of females it infects. [1] However bacterial density varies over development. Bacterial density is lowest in the embryo and increases over the lifespan of the fly, reaching its highest densities in the ovaries of females. Bacterial density directly affects the efficiency of Wolbachia inheritance, as females with lower Wolbachia density also produce daughters with a low bacterial density. [6] The forces driving differences in bacterial density may be epigenetic. If bacterial densities are low enough, females begin to produce males in spite of being infected with male-killing Wolbachia. [6] There is no evidence that a Wolbachia infection can be transmitted horizontally from an infected female fly to an uninfected female fly. Unlike extracellular symbiotic bacteria (e.g. Spiroplasma ), Wolbachia live inside their host cells, which likely reduces its ability to move between hosts. [5]
Infected sons are less likely to die from Wolbachia infection if their mother possessed a smaller bacterial density. [6] It is speculated that the bacterial density of Wolbachia inside a host can vary, depending on the antibiotic activity of larval or adult food sources, possible host defense mechanisms, the age of the host, bacterial interactions within the host, as well as the environmental conditions that the fly experiences. [6] Currently, there is no evidence for a mechanism in Drosophila innubila that suppresses or inhibits the male-killing effect of Wolbachia. [6]
Additionally, an unknown factor contributes to increased fitness benefits of Wolbachia infection. [5] The presence of a Wolbachia infection can increase the fitness of a female fly by increasing her size and enhancing her fertility. [5] Moreover, the D. innubila DNA nudivirus "DiNV" is a common viral infection amongst this species. [7] It has been shown that certain Wolbachia can protect their hosts against viral infection, even leading to biocontrol strategies that use Wolbachia infection to suppress the spread of viral diseases. [8] What role (if any) Wolbachia plays in defense against viruses is unclear. However, other studies that investigated the contribution of Wolbachia infection to the fitness of Drosophila species suggested that the bacteria can enhance survival of its host in the presence of oxidative stressors as well as prevent other pathogens from infecting the host by outcompeting them for host-derived resources like cholesterol. [9] [10] In addition, it is also suspected that Wolbachia may also be able to manipulate the expression of its host's DNA through utilization of host microRNA. [11]
The genome of D. innubila was sequenced for a study in 2019, and boasts a very high quality of assembly, rivalling that of the classic genetic model Drosophila melanogaster . This study highlighted the importance of the interaction between D. innubila and its viruses as implied by patterns of immune evolution in antiviral genes. Notably, natural selection on the immunity and antiviral pathways in D. innubila differ markedly from D. melanogaster, implying divergent evolutionary pressures. [4] The D. innubila DNA virus is similar to the D. melanogaster Kallithea virus . [12] As such, comparisons between D. melanogaster and D. innubila and their viruses promise to inform on the nature of host-virus interactions. [4]
In some mushroom-feeding Drosophila species, such as D. guttifera and D. neotestacea , the antimicrobial peptide gene Diptericin B has been pseudogenized. However this gene is maintained in D. innubila, and is activated upon infection. [13]
Drosophila is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the Tephritidae, a related family, which are also called fruit flies ; tephritids feed primarily on unripe or ripe fruit, with many species being regarded as destructive agricultural pests, especially the Mediterranean fruit fly.
Wolbachia is a genus of intracellular bacteria that infects mainly arthropod species, including a high proportion of insects, and also some nematodes. It is one of the most common parasitic microbes, and is possibly the most common reproductive parasite in the biosphere. Its interactions with its hosts are often complex, and in some cases have evolved to be mutualistic rather than parasitic. Some host species cannot reproduce, or even survive, without Wolbachia colonisation. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70% of all insect species are estimated to be potential hosts.
Spiroplasma is a genus of Mollicutes, a group of small bacteria without cell walls. Spiroplasma shares the simple metabolism, parasitic lifestyle, fried-egg colony morphology and small genome of other Mollicutes, but has a distinctive helical morphology, unlike Mycoplasma. It has a spiral shape and moves in a corkscrew motion. Many Spiroplasma are found either in the gut or haemolymph of insects where they can act to manipulate host reproduction, or defend the host as endosymbionts. Spiroplasma are also disease-causing agents in the phloem of plants. Spiroplasmas are fastidious organisms, which require a rich culture medium. Typically they grow well at 30 °C, but not at 37 °C. A few species, notably Spiroplasma mirum, grow well at 37 °C, and cause cataracts and neurological damage in suckling mice. The best studied species of spiroplasmas are Spiroplasma poulsonii, a reproductive manipulator and defensive insect symbiont, Spiroplasma citri, the causative agent of citrus stubborn disease, and Spiroplasma kunkelii, the causative agent of corn stunt disease.
Drosophila simulans is a species of fly closely related to D. melanogaster, belonging to the same melanogaster species subgroup. Its closest relatives are D. mauritiana and D. sechellia.
Nudiviruses are a family of animal viruses that constitute the family Nudiviridae. Insects and marine crustaceans serve as natural hosts. There are 11 species in this family, assigned to 4 genera. Diseases associated with this family include: death in larvae, chronic disease in adults.
Cytoplasmic incompatibility (CI) is a mating incompatibility reported in many arthropod species that is caused by intracellular parasites such as Wolbachia. These bacteria reside in the cytoplasm of the host cells and modify their hosts' sperm in a way that leads to embryo death unless this modification is 'rescued' by the same bacteria in the eggs. CI has been reported in many insect species, as well as in mites and woodlice. Aside from Wolbachia, CI can be induced by the bacteria Cardinium,Rickettsiella, Candidatus Mesenet longicola and Spiroplasma. CI is currently being exploited as a mechanism for Wolbachia-mediated disease control in mosquitoes.
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Arsenophonus nasoniae is a species of bacterium which was previously isolated from Nasonia vitripennis, a species of parasitoid wasp. These wasps are generalists which afflict the larvae of parasitic carrion flies such as blowflies, houseflies and flesh flies. A. nasoniae belongs to the phylum Pseudomonadota and family Morganellaceae. The genus Arsenophonus, has a close relationship to the Proteus (bacterium) rather than to that of Salmonella and Escherichia. The genus is composed of gammaproteobacterial, secondary-endosymbionts which are gram-negative. Cells are non-flagellated, non-motile, non-spore forming and form long to highly filamentous rods. Cellular division is exhibited through septation. The name 'Arsenophonus nasoniae gen. nov., sp. nov.' was therefore proposed for the discovered bacterium due to its characteristics and its microbial interaction with N. vitripennis. The type strain of A. nasoniae is Strain SKI4.
The microbiota are the sum of all symbiotic microorganisms living on or in an organism. The fruit fly Drosophila melanogaster is a model organism and known as one of the most investigated organisms worldwide. The microbiota in flies is less complex than that found in humans. It still has an influence on the fitness of the fly, and it affects different life-history characteristics such as lifespan, resistance against pathogens (immunity) and metabolic processes (digestion). Considering the comprehensive toolkit available for research in Drosophila, analysis of its microbiome could enhance our understanding of similar processes in other types of host-microbiota interactions, including those involving humans. Microbiota plays key roles in the intestinal immune and metabolic responses via their fermentation product, acetate.
Sigmavirus is a genus of viruses in the family Rhabdoviridae, order Mononegavirales. Sigmaviruses naturally infect dipterans. It is not to be confused with the Mega Man character of the same name.
Howardula aoronymphium is a species of nematode that infects specialist mushroom-feeding fruit flies such as Drosophila falleni and Drosophila neotestacea. Mated female nematodes pierce the fly larva cuticle and take up residence in the hemolymph where they mature alongside the fly. When the adult fly ecloses, the nematode motherworm has reached full size and sheds juvenile nematodes into the hemolymph which are eventually excreted by either the fly anus or ovipositor. Howardula nematodes can severely impact fly egg development, as infection can effectively sterilize some species.
Drosophila neotestacea is a member of the testacea species group of Drosophila. Testacea species are specialist fruit flies that breed on the fruiting bodies of mushrooms. These flies will choose to breed on psychoactive mushrooms such as the Fly Agaric Amanita muscaria. Drosophila neotestacea can be found in temperate regions of North America, ranging from the north eastern United States to western Canada.
Drosophila testacea is a member of the testacea species group of Drosophila. Testacea species are specialist fruit flies that breed on the fruiting bodies of mushrooms. Drosophila testacea can be found in temperate regions of Europe, extending to east Asia. Drosophila testacea and Drosophila orientacea can produce viable hybrids, though they are separated by geography and behavioural barriers. Drosophila testacea females will also readily mate with Drosophila neotestacea males, but viable hybrids are never produced. This hybrid inviability ) may be due to selfish X chromosomes and co-evolved suppressors. Alternately, differences in sex pheromone reception could underlie female readiness and male willingness to copulate.
The Drosophila testacea species group belongs to the Immigrans-tripunctata radiation of the subgenus Drosophila, and contains 4 species: Drosophila putrida, Drosophila neotestacea, Drosophila testacea, and Drosophila orientacea. Testacea species are specialist mushroom-feeding flies, and can metabolize toxic compounds in Amanita mushrooms. The Testacea species group is studied for its specialist ecology, population genetics, and bacterial endosymbionts. The North American species Drosophila neotestacea is perhaps the best-studied of the group for its interactions with parasitic wasps and nematodes, bacterial endosymbionts, and trypanosomatid parasites. Of note, selfish X chromosomes have been discovered in three of the four Testacea group species.
Spiroplasma poulsonii are bacteria of the genus Spiroplasma that are commonly endosymbionts of flies. These bacteria live in the hemolymph of the flies, where they can act as reproductive manipulators or defensive symbionts.
Diptericin is a 9 kDa antimicrobial peptide (AMP) of flies first isolated from the blowfly Phormia terranova. It is primarily active against Gram-negative bacteria, disrupting bacterial membrane integrity. The structure of this protein includes a proline-rich domain with similarities to the AMPs drosocin, pyrrhocoricin, and abaecin, and a glycine-rich domain with similarity to attacin. Diptericin is an iconic readout of immune system activity in flies, used ubiquitously in studies of Drosophila immunity. Diptericin is named after the insect order Diptera.
The Drosophila quinaria species group is a speciose lineage of mushroom-feeding flies studied for their specialist ecology, their parasites, population genetics, and the evolution of immune systems. Quinaria species are part of the Drosophila subgenus.
Mushroom-feeding Drosophila are a subset of Drosophila flies that have highly specific mushroom-breeding ecologies. Often these flies can tolerate toxic compounds from Amanita mushrooms.
John Jaenike is an ecologist and evolutionary biologist, and currently a professor at the University of Rochester New York. Jaenike was an early proponent of the Red Queen hypothesis, using the idea to explain the maintenance of sex. Jaenike is also known for his extensive work on mushroom-feeding Drosophila and the evolution of their inherited bacterial symbionts Wolbachia and Spiroplasma poulsonii.
The Morganellaceae are a family of Gram-negative bacteria that include some important human pathogens formerly classified as Enterobacteriaceae. This family is a member of the order Enterobacterales in the class Gammaproteobacteria of the phylum Pseudomonadota. Genera in this family include the type genus Morganella, along with Arsenophonus, Cosenzaea, Moellerella, Photorhabdus, Proteus, Providencia and Xenorhabdus.