Pristionchus pacificus

Pristionchus pacificus is a species of free-living nematodes (roundworms) in the family Diplogastridae. The species has been established as a satellite model organism to Caenorhabditis elegans, with which it shared a common ancestor 200-300 million years ago. The genome of P. pacificus has been fully sequenced,[1] which in combination with other tools for genetic analysis make this species a tractable model in the laboratory, especially for studies of developmental biology.

Pristionchus pacificus
Scientific classification
Kingdom:
Animalia
Phylum:
Nematoda
Class:
Chromadorea
Order:
Rhabditida
Family:
Diplogastridae
Genus:
Pristionchus
Species:
Pristionchus pacificus

Sommer, Carta, Kim & Sternberg, 1996

Mouth dimorphism

Like other species of Pristionchus, but unlike C. elegans and most other free-living nematodes, P. pacificus has a polyphenism in its mouthparts that allows the nematodes to specialize on different food sources.[2] The polyphenism has two forms, one of which (the "stenostomatous" form) is specialized for feeding on bacteria. An alternative ("eurystomatous") form, which responds to starvation of bacterial food and to crowding by other nematodes, has two large teeth, allowing it to feed as a predator on other nematodes. These two feeding types, which allow the nematodes to respond quickly to the environment, are specified by a hormonal and genetic cascade during larval development.[3]

Genomics

The Pristionchus pacificus genome was sequenced in 2005 and 2006.[4] The analysis of the P. pacificus has provided ecological information about this organism. It was determined that the genome of P. pacificus is larger than of the widely studied nematode C. elegans.[5] It was predicted that the genome of P. pacificus contains more than 26,000 protein coding genes.[6]

Scarab beetle association

It has been indicated that Pristionchus nematodes live in a necromenic association with scarab beetles.[7] "After the beetle dies, the nematode continues to develop and feed on microbes growing inside the dead beetle. The collection of bacteria, fungi and the nematodes work hand in hand to decompose the beetle carcass".[8] Thus, Pristionchus is an omnivorous feeder that can utilize bacteria, protozoa and fungi all of which grow on the carcass of scarab beetles as food sources.

References
  1. Dieterich C, Clifton SW, Schuster LN, Chinwalla A, Delehaunty K, Dinkelacker I, Fulton L, Fulton R, Godfrey J, Minx P, Mitreva M, Roeseler W, Tian H, Witte H, Yang SP, Wilson RK, Sommer RJ (2008). "The Pristionchus pacificus genome provides a unique perspective on nematode lifestyle and parasitism". Nature Genetics. 40 (10): 1193–1198. doi:10.1038/ng.227. PMC 3816844. PMID 18806794.
  2. Serobyan V, Ragsdale EJ, Sommer RJ (2014). "Adaptive value of a predatory mouth-form in a dimorphic nematode". Proceedings of the Royal Society of London B. 281 (1791): 20141334. doi:10.1098/rspb.2014.1334. PMC 4132687. PMID 25080344.
  3. Ragsdale, EJ; Müller, MR; Rödelsperger, C; Sommer, RJ (2013). "A developmental switch coupled to the evolution of plasticity acts through a sulfatase". Cell. 155 (4): 922–933. doi:10.1016/j.cell.2013.09.054. PMID 24209628.
  4. Borchert, N; Dieterich, C; Krug, K; et al. (2010). "Proteogenomics of Pristionchus pacificus reveals distinct proteome structure of nematode models". Genome Research. 20 (6): 837–846. doi:10.1101/gr.103119.109. PMC 2877580. PMID 20237107.
  5. Sommer J, Ralf, Mcgaughran, Angela et al (2013) The nematode Pristionchus pacificus as a model system for integrative studies in evolutionary biology, Molecular Ecology 22, 2380–2393
  6. Borchert, N; Dieterich, C; Krug, K; et al. (2010). "Proteogenomics of Pristionchus pacificus reveals distinct proteome structure of nematode models". Genome Research. 20 (6): 837–846. doi:10.1101/gr.103119.109. PMC 2877580. PMID 20237107.
  7. Weller, Andreas; et al. (January 21, 2010). "Quantitative Assessment of the Nematode Fauna Present on Geotrupes Dung Beetles Reveals Species-Rich Communities with a Heterogeneous Distribution". Journal of Parasitology. 96 (3): 525–531. doi:10.1645/GE-2319.1.
  8. DL, Riddle (April 23, 1981). "Interacting genes in nematode dauer larva formation". Nature. 290 (5808): 668–671. doi:10.1038/290668a0. PMID 7219552.
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