Pristionchus pacificus

Pristionchus pacificus	Contents	Rev: 09/28/2008
	Classification	Hosts
	Morphology and Anatomy	Life Cycle
Return to Pristionchus Menu	Economic Importance	Damage
	Distribution	Management
Return to Neodiplogasteridae Menu	Feeding	References
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Classification:

Secernentea
Diplogasteria
Diplogasterida
Diplogasteroidea: Neodiplogasteridae
Pristionchus pacificus Sommer, Carta, Kim & Sternberg, 1996

    Synonyms:

Extensive research conducted in the laboratory of Ralf Sommer, Max Planck Institute for Developmental Biology, Tubingen, Germany.

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Morphology and Anatomy:

Females:

Pristionchus pacificus – genome completed by NIH.

The Pristionchus genome is 169 Mb with >23,500 genes. (Caenorhabditis elegans genome is 100 Mb with 20,170 protein-coding genes).

Males:

Feeding:

Pristionchus spp. have cellulases, presumably through horizontal transfer from microbes (Smant, 1998).

Unlike the rhabditids, Pristionchus and other diplogasterids do not have a grinder in the basal bulb of the esophagus, so there are living bacteria in the intestine.

The mouth also differs from the tubular stoma of the rhabditids and has two forms, with teeth (eurystomatous) or without teeth (stenostomatous). Tooth formation is triggered by starvation, similar to the dauer trigger in C. elegans. Eurystomatous forms are able to feed on fungi.

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Hosts:

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Life Cycle:

Generation time is 4 days.

Dauerlarva formation occurs under conditions of high nematode density and low food availability, similar to C. elegans.

Oriental beetle (Japan) is the main host for P. pacificus. The dauerlarva invades the insect, waits for insect death and then feeds on decomposing microbes – a necromeny association. Each nematode species is able to detect its corresponding beetle by olfactory signals and the nematodes are attracted to the sex pheromones of the beetles.

P. pacificus is considered to be hermaphroditic but does produce males.

Sommer, R. 2008. Genetic and transgenic approaches in the nematode model Pristionchus pacificus.
Fifth International Congress of Nematology, Brisbane, Australia, July 2008.