Wolbachia

Wolbachia
Enlarge picture
Transmission electron micrograph of Wolbachia within an insect cell.
Credit:Public Library of Science / Scott O'Neill

Transmission electron micrograph of Wolbachia within an insect cell.
Credit:Public Library of Science / Scott O'Neill
Scientific classification
Kingdom:Bacteria
Phylum:Proteobacteria
Class:Alpha Proteobacteria
Order:Rickettsiales
Family:Rickettsiaceae
Genus:Wolbachia


Wolbachia is a genus of inherited bacterium which infects arthropod species, including a high proportion of insects. It is one of the world's most common parasitic microbes and is potentially the most common reproductive parasite in the biosphere, for example more than 16% of neotropical insect species carry this bacterium.[1]

Association with disease

Outside of Insecta, Wolbachia infects a variety of isopod species, spiders, mites, and many species of filarial nematodes (a type of parasitic worm), including those causing onchocerciasis ("River Blindness") and elephantiasis in humans as well as heart worms in dogs. Not only are these disease-causing filarial infected with Wolbachia, but Wolbachia seem to play an inordinate role in these diseases. A large part of the pathogenicity of filarial nematodes is due to host immune response toward their Wolbachia. Elimination of Wolbachia from filarial nematodes generally results in either death or sterility (Hoerauf et al. 2003). Consequently, current strategies for control of filarial nematode diseases include elimination of Wolbachia via the simple doxycycline antibiotic rather than far more toxic anti-nematode medications (Outland 2005, Taylor et al. 2005).

Role in sexual differentiation of hosts

Within arthropods, Wolbachia is notable for significantly altering the reproductive capabilities of its hosts. These bacteria can infect many different types of organs, but are most notable for the infections of the testes and ovaries of their hosts.

Wolbachia are known to cause four different phenotypes:
  • Male killing (death of infected males). This allows related infected females to be more likely to survive and reproduce.
  • feminization (infected males develop as females or infertile pseudo-females)
  • parthenogenesis(reproduction of infected females without males) and
  • Cytoplasmic incompatibility (the inability of Wolbachia-infected males to successfully reproduce with uninfected females or females infected with another Wolbachia strain). This has the advantage of making the Wolbachia strain more likely to become prevalent as opposed to other strains of Wolbachia. This can have the additional result of making Wolbachia more common as a whole.
Wolbachia are present in mature eggs, but not mature sperm. Only infected females pass the infection on to their offspring. It is thought that the phenotypes caused by Wolbachia, especially cytoplasmic incompatibility, may be important in promoting speciation. [2][3] Wolbachia can also cause misleading results in molecular cladistical analyses (Johnstone & Hurst 1996).

Research history

The bacteria were first identified in 1924 by Hertig and Wolbach in Culex pipiens, a species of mosquito.[4]

The genomes of Wolbachia from Drosophila melanogaster flies[5] and Brugia malayi nematodes[6] have been sequenced, and genome sequencing projects for several other Wolbachia strains are in progress.

A 2007 paper published in Science reports that a complete copy of the Wolbachia genome can be found within the genome of the fruit fly Drosophila ananassae and that Wolbachia appeared to have transmitted large segments of its genome into at least 7 other species.[7]

See also

References

1. ^ Werren JH, Guo L, Windsor DW. 1995. Distribution of Wolbachia in neotropical arthropods. Proc. R. Soc. London Ser. B 262:147–204
2. ^ Zimmer, Carl (2001). "Wolbachia: A Tale of Sex and Survival". Science 292 (5519): 1093-1095. DOI:10.1126/science.292.5519.1093. ISSN 0036-8075. 
3. ^ Bordenstein, S.; F. O'Hara, and J. Werren (2001). "Wolbachia-induced incompatibility precedes other hybrid incompatibilities in Nasonia". Nature 409 (6821): 707-710. DOI:10.1038/35055543. ISSN 0028-0836. 
4. ^ M. Hertig & S. B. Wolbach (1924). "Studies on Rickettsia-like microorganisms in insects". Journal of Medical Research 44: 329–374. 
5. ^ Wu M et al. (March 2004). "Phylogenomics of the reproductive parasite Wolbachia pipientis wMel: a streamlined genome overrun by mobile genetic elements". PLoS Biology 2 (3): E69. 
6. ^ Foster J et al. (April 2005). "The Wolbachia genome of Brugia malayi: endosymbiont evolution within a human pathogenic nematode". PLoS Biology 3 (4): e121. 
7. ^ Dunning Hotopp, JC et al.. "Widespread Lateral Gene Transfer from Intracellular Bacteria to Multicellular Eukaryotes", Science, August 30, 2007. 

Further reading

External links

The Public Library of Science (PLoS) is a nonprofit open access scientific publishing project aimed at creating a library of open access journals and other scientific literature under an open content license.
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Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. Scientific classification also can be called scientific taxonomy, but should be distinguished from folk taxonomy, which lacks scientific basis.
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Bacteria

Phyla

Actinobacteria
Aquificae
Chlamydiae
Bacteroidetes/Chlorobi
Chloroflexi
Chrysiogenetes
Cyanobacteria
Deferribacteres
Deinococcus-Thermus
Dictyoglomi
Fibrobacteres/Acidobacteria
Firmicutes
Fusobacteria
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Proteobacteria
Stackebrandt et al., 1986

Orders

Alpha Proteobacteria
   Caulobacterales - e.g. Caulobacter
   Parvularculales
   Rhizobiales - e.g.
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Rickettsiales
Gieszczkiewicz, 1939

Families

Rickettsiaceae
Ehrlichiaceae
Holosporaceae
The Rickettsiales, also called rickettsias, are an order of small proteobacteria. Most of those described survive only as endosymbionts of other cells.
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Rickettsiaceae
Pinkerton, 1936

Genera

Rickettsia
Orientia
Wolbachia

The Rickettsiaceae are a family of bacteria, including most notably the genus Rickettsia.
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genus (plural: genera) is part of the Latinized name for an organism. It is a name which reflects the classification of the organism by grouping it with other closely similar organisms.
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Bacteria

Phyla

Actinobacteria
Aquificae
Chlamydiae
Bacteroidetes/Chlorobi
Chloroflexi
Chrysiogenetes
Cyanobacteria
Deferribacteres
Deinococcus-Thermus
Dictyoglomi
Fibrobacteres/Acidobacteria
Firmicutes
Fusobacteria
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Arthropoda
Latreille, 1829

Subphyla and Classes
  • Subphylum Trilobitomorpha
  • Trilobita - trilobites (extinct)
  • Subphylum Chelicerata

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Insecta
Linnaeus, 1758

Orders
Subclass Apterygota
* Archaeognatha (bristletails)
* Thysanura (silverfish)
Subclass Pterygota
* Infraclass Paleoptera (Probably paraphyletic)

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Isopoda
Latreille, 1817

Suborders

Anthuridea
Asellota
Calabozoida
Epicaridea
Flabellifera
Microcerberidea
Oniscidea
Phreatoicidea
Valvifera
Isopods
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Araneae
Clerck, 1757

Diversity
111 families, 40,000 species

Suborders

Mesothelae
Mygalomorphae
Araneomorphae
 See table of families

Spiders
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Mites, including ticks, belong to the subclass Acarina (also known as Acari) and the class Arachnida. Mites are among the most diverse and successful of all the invertebrate groups.
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Nematoda
Rudolphi, 1808

Classes

Adenophorea
   Subclass Enoplia
   Subclass Chromadoria
Secernentea
   Subclass Rhabditia
   Subclass Spiruria
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Parasitic worms or helminths are a division of parasites which, unlike external parasites such as lice or fleas, live inside their host. They are worm-like organisms that live and feed off living hosts receiving nourishment and protection while disrupting their hosts'
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Onchocerciasis
Classification & external resources

ICD-10 B 73.
ICD-9 125.3

DiseasesDB 9218

eMedicine med/1667   oph/709

Onchocerca volvulus

O.

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MeSH D004605

Elephantiasis is a disease that is characterized by the thickening of the skin and underlying tissues, especially in the legs and genitals.

Causes

Elephantiasis generally results from obstructions of the lymphatic vessels.
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Heartworm is a parasitic roundworm (Dirofilaria immitis) that is spread from host to host through the bites of mosquitoes.

Heartworm is a type of filaria, a small thread-like worm.
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Doxycycline (INN) (IPA: [ ˌdɒksɪˈsaɪklin ]) is a member of the tetracycline antibiotics group and is commonly used to treat a variety of infections.
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The testicle (from Latin testis, meaning "witness",[1] plural testes) or ballock is the male generative gland in animals. This article will concentrate on mammalian testicles unless otherwise noted.
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For ovary as part of plants see ovary (plants)
An ovary is an egg-producing reproductive organ found in female organisms. They are usually purple. It is often found in pairs as part of the vertebrate female reproductive system.
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phenotype describes the total physical appearance of an organism, as opposed to its genotype. This genotype-phenotype distinction was proposed by Wilhelm Johannsen in 1911 to make clear the difference between an organism's heredity and what that heredity produces.
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Parthenogenesis (from the Greek παρθένος parthenos, "virgin", + γένεσις genesis
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strain is used in three related ways.

Microbiology/Virology

A strain is a genetic variant or subtype of a virus or bacterium. For example, a "flu strain" is a certain biological form of the influenza or "flu" virus. Compare clade.
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Molecular phylogeny is the use of the structure of molecules to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a so-called phylogenetic tree.

Every living organism contains DNA, RNA, and proteins.
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Cladistics is a philosophy of classification that arranges organisms only by their order of branching in an evolutionary tree and not by their morphological similarity, in the words of Luria et al. (1981).
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20th century - 21st century
1890s  1900s  1910s  - 1920s -  1930s  1940s  1950s
1921 1922 1923 - 1924 - 1925 1926 1927

Year 1924 (MCMXXIV
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MOSQUITO is a stream cypher algorithm designed by Joan Daemen and Paris Kitsos. It has been submitted to the eSTREAM Project of the eCRYPT network.


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D. melanogaster

Binomial name
Drosophila melanogaster
Meigen, 1830[1]

Drosophila melanogaster (from the Greek for black-bellied dew-lover
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Brugia malayi
Brug 1927

Brugia malayi is a filarial roundworm which causes filariasis in humans.[1] Identified by Lichtenstein and named by Brug in 1927 as distinct from Wuchereria bancrofti
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