9

Yes there are reports of RNA directly inhibiting transcription. RNA induced transcriptional silencing (RITS) is a well known pathway in Schizosaccharomyces pombe (fission yeast). Initial heterochromatinization is dependent on the RNA (as a DNA identfication module) that guides other functional proteins to the target (Also see Djupedal et al., 2009). piRNA ...


6

A clarification on introns and exons. While it is true that introns are not a part of the mRNA as March Ho said, they are essentially transcribed. This may seem trivial but it is important to note. So: Both introns and exons arise from the transcribed region Exons need not necessarily form the ORF (i.e. be translated to proteins) Regarding intronic RNAs: ...


6

While Ankur's answer is correct, it must be noted that not all non-coding RNAs are introns. An intron must be excised from an mRNA, which therefore means that any non-coding RNA that is not part of an mRNA cannot be an intron. For example, rRNA and tRNA are all examples of non-coding RNAs that are not introns, since they are not part of mRNA. miRNA may ...


5

People often imprecisely say that type of regulation takes place on the order of many minutes to hours, and that may be as precise as you can get given the variable kinetics of any given pathway. Also, all genes in eukaryotes require general transcription factors, but basically all of them also require activators to act first to recruit the GTFs and ...


3

I don't really understand why mRNA processing doesn't simply occur in the cytoplasm. To be clear, P-bodies are in the cytoplasm (ie they are not separated by a membrane). There is also dynamic exchange of components between the ribonucleoprotein complex and free cytoplasmic pool (1): Most P-body components are distributed diffusely throughout the ...


3

Small non-coding RNAs are NOT generally abbreviated as sRNA but as sncRNA, if anything. I say "if anything" because the "small" part is subjective and just a portmanteau descriptor. The straight answer to your question is as Forest has written: miRNAs are a specific type of small non-coding RNA, some of which appear to function in the regulation of gene ...


2

There are many studies that have used RNAi against the plant parasite M. incognita. The fundamental idea is that RNAi is directed against one of the vital genes of this nematode. Since, RNAi causes downregulation of the target gene, the nematode dies (or becomes ineffective in infecting) because of the loss of function of these important genes. As you might ...


2

miRNA are one member of the small non-coding RNA family. "Small non-coding" is a pretty broad term that encompasses microRNA and short interfering RNA, among other regulatory RNA species. The key word is 'regulatory'; each type of small non-coding RNA works by binding complementary sequences to exert some sort of regulatory control over gene expression. ...


2

Yup - in a lot of cases the transcription of non-coding RNAs is from introns. Some of them are within genes (intragenic) and others are intergenic (between genes). In humans, a large number of both have been documented http://www.nature.com/ng/journal/v47/n3/full/ng.3192.html Coming to your question about why they are not transcribed - it again comes down ...


2

Looking to a standard source of definitions, the Systems Biology Ontology definition of inhibition is "Negative modulation of the execution of a process." As such, it doesn't really make sense to talk about inhibiting a gene per se. What people are actually doing when they say that is using a shorthand to describe inhibiting either the expression ...


1

RNAi can happen in the nucleus as well. This is better documented in C.elegans but there are some references supporting nuclear RNAi in mammalian cells too: https://doi.org/10.1073/pnas.1707440114 https://doi.org/10.1016/j.celrep.2013.12.013 https://doi.org/10.1093/nar/gkv1305


1

They introduced a foreign gene responsible for petunia leaf colour, with the intentions of up-regulating gene expression for this colour, which was purple. What was observed however was intriguing. Rather than an up-regulation of the purple colour, the leaves were all white instead. This finding showed that the RNAi system in plants recognised the foreign ...


1

What they're doing is called two-step PCR. In step one, some gene-specific primers with tags amplify genomic DNA, but the product has adapter regions now added to each end. In the second step, you add primers that complement the tag/adapter region and have T7 promoter sequences at the ends. Your second product will have the adapter region, and the T7 ...


1

The question is little bit unclear: is in vitro or in vivo introduction in question? In vivo: As the nematode feeds on the plant during its parasitic phase, it consequently assures the introduction of dsRNA and/or siRNA molecules into the nematode’s digestive system. in vitro introduction etc -> The status of RNAi-based transgenic research in ...


1

The answer is in the slides you provided a link to. The key fact is that Craig & Andy did careful controls to show that it was the presence of dsRNA in both the sense control, and in the anti-sense experimental sample that was responsible for the RNAi-mediated knock-down. Actually, Ken Kemphues showed this earlier in a Nature paper (the control also ...


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