science

RNA22

RNA22 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 RNA22 rather than just read about it. In short: Rna22 is a pattern-based algorithm for the discovery of microRNA target sites and the corresponding heteroduplexes. The algorithm is conceptually distinct from other methods for predicting microRNA:mRNA heteroduplexes in that it does not use experimentally validated heteroduplexes for training, instead relying only on the sequences of known mature miRNAs that are found in the public databases.

Key takeaways

RNA22 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect RNA22 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of RNA22 from memory before moving on to harder problems.

Reference excerpt

Rna22 is a pattern-based algorithm for the discovery of microRNA target sites and the corresponding heteroduplexes. The algorithm is conceptually distinct from other methods for predicting microRNA:mRNA heteroduplexes in that it does not use experimentally validated heteroduplexes for training, instead relying only on the sequences of known mature miRNAs that are found in the public databases. The key idea of rna22 is that the reverse complement of any salient sequence features that one can identify in mature microRNA sequences (using pattern discovery techniques) should allow one to identify candidate microRNA target sites in a sequence of interest: rna22 makes use of the Teiresias algorithm to discover such salient features. Once a candidate microRNA target site has been located, the targeting microRNA can be identified with the help of any of several algorithms able to compute RNA:RNA heteroduplexes. A new version (v2.0) of the algorithm is now available: v2.0-beta adds probability estimates to each prediction, gives users the ability to choose the sensitivity/specificity settings on-the-fly, is significantly faster than the original, and can be accessed through http://cm.jefferson.edu/rna22/Interactive/. Rna22 neither relies on nor imposes any cross-organism conservation constraints to filter out unlikely candidates; this gives it the ability to discover microRNA binding sites that may not be conserved in phylogenetically proximal organisms. Also, as mentioned above, rna22 can identify putative microRNA binding sites without needing to know the identity of the targeting microRNA. A notable property of rna22 is that it does not require the presence of the exact reverse complement of a microRNA's seed in a putative target permitting bulges and G:U wobbles in the seed region of the heteroduplex. Lastly, the algorithm has been shown to achieve high signal-to-noise ratio. Use of rna22 led to the discovery of "non-canonical" microRNA targets in the coding regions of the mouse Nanog, Oct4 and Sox2. Most of these targets are not conserved in the human orthologues of these three transcription factors even though they reside in the coding region of the corresponding mRNAs. Moreover, most of these targets contain G:U wobbles, one or more bulges, or both, in the seed region of the heteroduplex. In addition to coding regions, rna22 has helped discover non-canonical targets in 3'UTRs. A recent study examined the problem of non-canonical miRNA targets using molecular dynamics simulations of the crystal structure of the Argonaute-miRNA:mRNA ternary complex. The study found that several kinds of modifications, including combinations of multiple G:U wobbles and mismatches in the seed region, are admissible and result in only minor structural fluctuations that do not affect the stability of the ternary complex. The study also showed that the findings of the molecular dynamics simulation are supported by HITS-CLIP (CLIP-seq) data. These results suggest that bona fide miRNA targets transcend the canonical seed-model in turn making target prediction tools like rna22 an ideal choice for exploring the newly augmented spectrum of miRNA targets.

References

Worked examples

Example 1 — a first encounter with RNA22

Start with the simplest possible case. Write down what RNA22 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 RNA22 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 RNA22 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 RNA22

In research: RNA22 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 RNA22 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: RNA22 is common in secondary-school and first-year university syllabi. It links to neighbouring topics MicroRNA, Pattern matching, RNA, so understanding it makes those chapters shorter.
In everyday life: Look for RNA22 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 RNA22 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what RNA22 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 RNA22 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is RNA22 in simple terms?

Why does RNA22 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 RNA22?

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 RNA22.