Wolbachia pipientis

A Microbial Biorealm page on the genus Wolbachia pipientis

In a stained egg of the small parasitic wasp, Trichogramma kaykai, are brightly staining Wolbachia. The bacteria accumulate at the end of the egg that is destined to develop into the reproductive organs. Wolbachia induce the eggs of this wasp to develop into female offspring without fertilization. Photo Credit: Merijn Salverda and Richard Stouthamer.

Classification

Higher order taxa

Bacteria; Proteobacteria; Alphaproteobacteria; Rickettsiales; Rickettsiaceae; Wolbachieae; Wolbachia

Species

Wolbachia pipientis

NCBI: Taxonomy

Genus species

Description and significance

Wolbachia are gram-negative bacteria that form intracellular inherited infections in many invertebrates. They are extremely common with 20-75% of all insects being infected. Moreover they infect numerous non-insect invertebrates including nematodes, mites and spiders. The limits of the host range of Wolbachia are not fully appreciated at this time. Much of the success of Wolbachia can be attributed to the diverse phenotypes that result from infection. These range from classical mutualism to reproductive parasitism as characterized by the ability of Wolbachia to override chromosomal sex determination, induce parthenogenesis, selectively kill males, influence sperm competition and generate cytoplasmic incompatibility in early embryos. The unique biology of Wolbachia has attracted a growing number of researchers interested in questions ranging from the evolutionary implications of infection through to the use of this agent for pest and disease control

Genome structure

Statistics for Wolbachia pipientis.

Analysis of the genome, in particular phylogenomic comparisons with other intracellular bacteria, has revealed many insights into the biology and evolution of Wolbachia. For example, the genome is unique among sequenced obligate intracellular species in both being highly streamlined and containing very high levels of repetitive DNA and mobile DNA elements. This observation, coupled with multiple evolutionary reconstructions, suggests that natural selection is somewhat inefficient, most likely owing to the occurrence of repeated population bottlenecks.

Cell structure and metabolism

Genome analysis predicts many metabolic differences with the closely related Rickettsia species, including the presence of intact glycolysis and purine synthesis, which may compensate for an inability to obtain ATP directly from its host, as Rickettsia can. Other discoveries include the apparent inability of Wolbachia to synthesize lipopolysaccharide.

Ecology

Despite the ability of Wolbachia to infect the germline of its host, no evidence has yet been found for either recent lateral gene transfer between Wolbachia and D. melanogaster or older transfers between Wolbachia and any host. Evolutionary analysis further supports the hypothesis that mitochondria share a common ancestor with the alpha-Proteobacteria, but shows little support for the grouping of mitochondria with species in the order Rickettsiales.

Pathology

Wolbachia, a bacterial endosymbiont of diverse arthropods, affects its host's reproduction and so is consequential for its host's fitness. In the fruit fly. Host interactions are complex and range from mutualistic to pathogenic, depending on the combination of host and Wolbachia involved. Most striking are the various forms of “reproductive parasitism” that serve to alter host reproduction in order to enhance the transmission of this maternally inherited agent. These include parthenogenesis (infected females reproducing in the absence of mating to produce infected female offspring), feminization (infected males being converted into functional phenotypic females), male-killing (infected male embryos being selectively killed), and cytoplasmic incompatibility (in its simplest form, the developmental arrest of offspring of uninfected females when mated to infected males).

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

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References

Description and Significance:

• Office of Legislative & Public Affairs
• Wolbachia - wolbachia.sols.uq.edu.au

Genome structure

Genome data for Wolbachia pipientis (TIGR)