science

Pristionchus pacificus

Pristionchus pacificus is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Pristionchus pacificus rather than just read about it. In short: 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.

Key takeaways

Pristionchus pacificus belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Pristionchus pacificus to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Pristionchus pacificus from memory before moving on to harder problems.

Reference excerpt

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, which in combination with other tools for genetic analysis make this species a tractable model in the laboratory, especially for studies of developmental biology.

Mouth dimorphism Like other species of Pristionchus and many other free-living nematodes, P. pacificus exhibits a polyphenism in its mouthparts that allows individual nematodes to specialize on different food sources, which has made the species a case study in phenotypic plasticity. The polyphenism has two forms (morphs). The most common type, at least in wild-type lab strains, is the "eurystomatous" morph, which can feed on both bacteria and other nematode species. The "stenostomatous" morph, on the other hand, is specialised for feeding on bacteria exclusively. Differentiation into one or the other morph depends on a combination of environmental conditions and stochasticity. The main morphological differences can be seen in the mouthparts. The eurystomatous morph has a secondary tooth and a wider buccal cavity. The secondary tooth allows the eurystomatous morph to feed on other nematode worms. The two feeding morphs, which allow the nematodes to respond quickly to changing environments, are specified by a hormonal and genetic cascade during larval development.

Self-recognition As a predatory species that feeds on related species, it is likely that there is a selective pressure for self-recognition, i.e. recognition of conspecifics. P. pacificus does not feed on conspecifics and therefore must be capable of distinguishing them from other nematode species. Self-recognition is not cilia-dependent, unlike prey recognition.

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

Ecology It has been indicated that Pristionchus nematodes live in a necromenic association with scarab beetles. "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". Thus, Pristionchus is an omnivore that can utilize bacteria, protozoa and fungi as food sources, all of which grow on the carcasses of scarab beetles.

References

External links View the priPac1 genome assembly in the UCSC Genome Browser

Illustrations

Worked examples

Example 1 — a first encounter with Pristionchus pacificus

Start with the simplest possible case. Write down what Pristionchus pacificus claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Pristionchus pacificus before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Pristionchus pacificus ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Pristionchus pacificus

In research: Pristionchus pacificus appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Pristionchus pacificus in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Pristionchus pacificus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Animal models, Nematodes described in 1996, Rhabditida, so understanding it makes those chapters shorter.
In everyday life: Look for Pristionchus pacificus outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Pristionchus pacificus in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Pristionchus pacificus means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Pristionchus pacificus out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Pristionchus pacificus in simple terms?

Why does Pristionchus pacificus matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Pristionchus pacificus?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Pristionchus pacificus.