Pristionchus

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Pristionchus
Pristionchus pacificus

Pristionchus pacificus

Systematics
Over trunk : Molting animals (Ecdysozoa)
Trunk : Roundworms (Nematoda)
Class : Chromadorea
Order : Rhabditida
Family : Diplogastridae
Genre : Pristionchus
Scientific name
Pristionchus
Circle , 1932

Pristionchus is the name of a genus of roundworms (nematodes) that was established by Hans August Kreis in 1932. It currently contains 48 described species , all of which seem to be associated with insects. However, the type specimen of some of the species described earlier is missinganda number of synonyms are to be expected giventhe great phenotypic variability of these nematodes. Conversely, a number of new species have been discovered in recent years with the help of improved research methods.

Way of life

Many nematodes live freely in and on the soil, such as Caenorhabditis elegans , which can be found in compost heaps. Other representatives of roundworms live parasitically, such as Wuchereria bancrofti , the pathogen that causes elephantiasis . Pristionchus takes an intermediate stage. These nematodes live as permanent larvae in and on beetles , where they feed on bacteria and fungi . So they do not practice parasitism, but are commensals . The Pristionchus species wait for their host to die naturally in order to feed on the microorganisms that colonize the beetles during the decomposition process. Only then is the further development of the nematode guaranteed. This way of life is also known as necromenia .

distribution

Pristionchus maupasi , a species native to Europe , is associated with cockchafer ( field cockchafer ), the European Pristionchus lheritieri with dung beetles ( common dung beetle ). The Pristionchus pacificus , originally from North America, can also be found on a beetle (genus Phyllophaga ). Pristionchus uniformis is associated with the Colorado potato beetle in the USA as well as in Europe . Since this beetle has only been native to Europe since 1877, it can be assumed that Pristionchus uniformis spread here along with this beetle. The range of the individual species is therefore identical to the habitat of their host beetles.

Reproduction

Like Caenorhabditis, Pristionchus entomophagus and Pristionchus maupasi are hermaphrodites and can fertilize themselves. Males are rarely found in these species. However, hermaphrodites are likely to have arisen several times in the tribal history of the genus Pristionchus , since the two species are not particularly closely related, but rather belong to two different clades within the genus. Many species found in North America, such as Pristionchus aerivorus and Pristionchus pseudaerivorus , some of which occur together in the same species of beetle, are of separate sexes. It can hybrid form between species but in which the males are not viable.

Model organism for evolutionary developmental biology

The Department of Evolutionary Biology at the Max Planck Institute for Developmental Biology in Tübingen deals with the genus and has established the species Pristionchus pacificus as a satellite organism for Caenorhabditis elegans . This allows relationships to be established between the two related nematodes, whose lines of development, however, separated more than 200 million years ago. Both organisms have been well studied in terms of molecular genetics and anatomy . Caenorhabditis elegans has become a popular model organism , especially in developmental biology and genetics , which numerous Nobel Prize winners have studied.

Although Pristionchus pacificus was first described by Ralf J. Sommer in 1996 , its genome has already been sequenced.

Species list (selection)

  • Pristionchus pacificus , occurs in North and Central America with a beetle of the genus Phyllophaga ; popular laboratory animal, is bred on Escherichia coli
  • Pristionchus entomophagus , is found in Europe; hermaphrodite
  • Pristionchus maupasi , is found in Europe in connection with the field cockchafer ( Melolontha melolontha )
  • Pristionchus lheritieri , lives in the common dung beetle ( Geotrupes stercorarius )
  • Pristionchus uniformis , is associated with the Colorado potato beetle ( Leptinotarsa ​​decemlineata ) in North America as well as in Europe
  • Pristionchus aerivorus , from the east coast of the USA, attacks scarab beetles
  • Pristionchus pseudaerivorus , also from the east coast of the USA, described as a new species in 2006
  • Pristionchus fissidentatus , is found in both Nepal and Reunion Island; hermaphrodite
  • Pristionchus elegans , from Japan
  • Pristionchus exspectatus , a supposed sister species of the laboratory animal Pristionchus pacificus
  • Pristionchus arcanus , a species closely related to P. pacificus and P. exspectatus ; described from termites in Japan
  • Pristionchus japonicus

Individual evidence

  1. ↑ a b M. Herrmann, WE Mayer, RJ Sommer: Sex, bugs and Haldane's rule: the nematode genus Pristionchus in the United States. In: Frontiers in Zoology. 2006. (frontiersinzoology.com)
  2. ↑ M. Herrmann, WE Mayer, RJ Sommer: Nematodes of the genus Pristionchus are closely associated with scarab beetles and the Colorado potato beetle in Western Europe. In: Zoology. Volume 109, 2006, pp. 96-108.

literature

  • HA circle: Contributions to the knowledge of plant parasitic nematodes. In: Journal of Parasitic Studies. Volume 5, 1932, pp. 184-194.
  • H. Zauner, WE Mayer, M. Herrmann, A. Weller, M. Erwig, RJ Sommer: Distinct patterns of genetic variation in Pristionchus pacificus and Caenorhabditis elegans, two partially selfing nematodes with cosmopolitan distribution. In: Molecular Ecology. Volume 16, No. 6, 2007, pp. 1267-1280. doi: 10.1111 / j.1365-294X.2006.03222.x
  • M. Herrmann, W. Mayer, R. Hong, S. Kienle, R. Minasaki, RJ Sommer: The nematode Pristionchus pacificus (Nematoda: Diplogastridae) is associated with the Oriental beetle Exomala orientalis (Coleoptera: Scarabaeidae) in Japan. In: Zoological Science. Volume 24, 2007, pp. 883-889.
  • N. Kanzaki, EJ Ragsdale, M. Herrmann, WE Mayer, R. Tanaka, RJ Sommer: Description of three Pristionchus species (Nematoda: Diplogastridae) from Japan that form a cryptic species complex with the model organism P. pacificus. In: Zoological Science. Volume 29, 2012, pp. 403-417.
  • N. Kanzaki, EJ Ragsdale, M. Herrmann, RJ Sommer: Two New Species of Pristionchus (Rhabditida: Diplogastridae): P. fissidentatus n. Sp. from Nepal and La Réunion Island and P. elegans n. sp. from Japan. In: Journal of Nematology. Volume 44, 2012, pp. 80-91.
  • WE Mayer, M. Herrmann, RJ Sommer: Phylogeny of the nematode genus Pristionchus and implications for biodiversity, biogeography and the evolution of hermaphroditism. In: BMC Evolutionary Biology. 2007. (biomedcentral.com)

Web links

Commons : Pristionchus  - collection of images, videos and audio files