how can we assess RNA quality?
340538
Because mRNA comprises only 1-3% of total RNA samples it is not readily detectable even with the most sensitive of methods. Ribosomal RNA, on the other hand, makes up >80% of total RNA samples, with the majority of that comprised by the 28S and 18S rRNA species (in mammalian systems). mRNA quality has historically been assessed by electrophoresis of total RNA followed by staining with ethidium bromideThis method relies on the assumption that rRNA quality and quantity reflect that of the underlying mRNA population. Because mammalian 28S and 18S rRNAs are approximately 5 kb and 2 kb in size, the theoretical 28S:18S ratio is approximately 2.7:1; but a 2:1 ratio has long been considered the benchmark for intact RNA. While crisp 28S and 18S rRNA bands are indicative of intact RNA, it is less clear how these long-lived and abundant molecules actually reflect the quality of the underlying mRNA population, which turns over much more rapidly. \n\nVisual assessment of the 28S:18S rRNA ratio on agarose gels is somewhat subjective because appearance of rRNA bands is affected by electrophoresis conditions, amount of RNA loaded, and saturation of ethidium bromide fluorescence ( An improved analytical tool for total RNA analysis is the Agilent 2100 bioanalyzer, which uses a combination of microfluidics, capillary electrophoresis, and fluorescence to evaluate both RNA concentration and integrity analysis  Another advantage is that it requires very small inputs, allowing the user to assay RNA quality in limiting samples.
925374
transcription in cells makes RNA copies of DNA.
72500
Come on StingRay, the question wasn't that obscure. A google search for "gene array" brings up 146,000 hits. It's also known as a micro array. A micro array tests an array of genes. The idea is based on Northern blots, which is another way of testing interactions between RNA and DNA.\n\nThe question a micro array tries to answer has to do with gene expression. It is useful to know, in a given type of cell, which genes are expressed, meaning that they are turned on, and which are not. The array basically looks at the content of transcripts in a cell, meaning the genes that have been made into RNA. When a gene is activated, RNA is produced from that segment of DNA, and then the protein is produced from the RNA (non-coding RNAs are a different topic). Looking at the messenger RNA transcripts, or mRNA, is a way of looking at gene activation.\n\nThere are various ways of doing it, and you can check the links below for more specific technical information. The short story is that a slide is made that contains a set of short sequences that correspond specifically to different genes. An array might contain tens of thousands of genes. This slide is exposed to transcripts from a cell, and where there are matches, they will hybridize, or interact. So if a slide had 10,000 representations, you could  expose it to, say, transcripts from a normal colon cell, and a certain number of genes would interact, meaning that those were turned on in that cell. You could also test lines from various colon cancers, and then see which interactions are the same, and which are different. This is a way of getting information about which genes may be involved in cancer, as well as in the development process that causes cells to define what type they will be.\n\nThere are various ways of reading out the interaction. Typically, there is a fluorescent signal, and the strength of the signal tells how strong the interaction is, which indicates how highly the gene is expressed. This is all read by computer, and output into a graphic which typically shows upregulated genes in green, and downregulated genes in red. The results are analyzed by statistical methods, and to be sure they are valid, they need to be tested again in biological systems.
810621
I have no idea about the second part of your question, and I'm not entirely sure if it's true, but I'll tell you what RNA is.\n\nRNA is essentially a copy of DNA that can travel out of the nucleus and to other parts of the cell. RNA is used as instructions. DNA can't leave the cell or it'll be destroyed by enzymes looking for viruses.\n\nMessenger RNA (or mRNA) is the one that goes from the nucleus to the ribosomes (where proteins are made) with instructions for which specific protein is to be made. Transfer RNA (tRNA) brings the appropriate amino acids (pieces of protein) to the Ribosomes so that the desired proteins can be made.\n\nthere are many other types of RNA, such as ribosomal RNA, but I know much less about those.\nhope this helps!
567614
The other major way to study transcription level other than PCR is Northern blotting, in which you run all poly A+ RNA on a gel, and probe with radioactive complementary strand of ubiquitin cDNA- An easier way would be to check the DNA databases for ubiquitin primers used for quantitative PCR- Ubiquitin is a highly studied protein, and thus there are numerous PCR primer sequences available in these databases.
172269
take an epindorph tube, place about 500 microlitres of blood, centrifuge, remove supernatent, wash with PBS buffer, repeat 3x, by an RNA isolation kit from roche and foolow the instruction!!
28295
cDNA stands for complementary DNA. It's something that is used in laboratories, not created in cells (viruses aside). To create a cDNA library, you would isolate the RNA from a cell. The RNA transcripts should represent all of the genes that are being transcribed at that time in that cell. These would be the messenger RNAs or mRNAs. Using reverse transcriptase and primers in a tube, a DNA copy is made of all the RNA transcripts. This DNA is complementary to the RNA, which is why it is so named. DNA is much more stable than RNA and easier to work with, so this cDNA library can be used for many types of experiments that would be difficult to do directly from RNA.\n\nHow is such a library significant to the production of gene products? Well, the cell doesn't use it, so it's not significant in the sense of a cell needing it to make a gene product. The gene product is what is made from a gene, which is usually (but not always) a protein. Analyzing a cDNA library can tell what proteins could be made in a given situation. There are many types of regulation that are important in translation (when protein is made from mRNA), so looking at gene expression at the mRNA level is not the same as looking at protein expression. But it's a step on the way.
478310
As far as using for detection, its very vulnerable to showing false positives from non-specific binding.  In addition, because of the relatively low level of mRNA, it can only be used for fairly abundant messages.  It is somewhat difficult to separate non-specific from specific binding, but of course it can be done.  In addition, it only shows the presence of message-it does not tell about the level of protein translation.
409458
Here is the first paragraph of a review article answering your question, see the source below...\n\nLike the discovery of splicing three decades ago, the unearthing of RNA interference (RNAi) and microRNAs (miRNAs) once again has everyone’s attention focused on posttranscriptional phenomena. During RNAi, dsRNA formed in cells by DNA- or RNA-dependent synthesis is processed to ∼20 bp small interfering RNAs (siRNAs) containing 2 nt (nucleotide) 3′ overhangs. These siRNAs are then incorporated into an R NA-i nduced s ilencing c omplex (RISC), which mediates the degradation of mRNAs with high sequence complementarity to the siRNA. MiRNAs are ∼21 nt regulatory RNAs excised from genome-encoded precursors folding into dsRNA-like hairpins. With few exceptions, animal miRNAs base pair imperfectly to the 3′-untranslated region of target mRNAs and inhibit protein accumulation by an unknown mechanism, while plant miRNAs show nearly precise complementarity to their targets and trigger mRNA degradation. This miRNA dualism and observations that miRNAs can act under some circumstances as siRNAs, and vice versa, highlight similarities between the siRNA and miRNA pathways. Indeed, maturation of both RNA classes involves Dicer proteins, and, like siRNAs, miRNAs function as RNP particles, miRNPs or miRISCs, whose composition and, probably, assembly are related to those of the RISC (Sontheimer [2005]; Tomari and Zamore [2005] [ Sontheimer, 2005, Tomari and Zamore, 2005]; consult these reviews when discussed findings are not specifically referenced).
882950
Transcription is the process of creating an RNA copy of one's DNA or mRNA.  RNA polymerase is responsible for this process.  This process is very important because mRNA is then used in "translation" to form proteins by means of a Ribosome.  \n\nYou need a TATA box for transcription.  There are three types of RNA polymerase: types 1, 2 and 3.  Type 3 RNA Polymerase typically are the ones with the TATA boxes.\n\nTake a look at this website to watch how RNA polymerase synthesizes a new mRNA through transcription:\nhttp://www.phschool.com/science/biology_place/biocoach/transcription/complete.html\n\nHave fun!
8687
mRNA  \nCapped messenger RNA is produced directly from your plasmid that contains a T7 or SP6 promoter. It is purified by our proprietary PUREmessenger™ technology. PUREmessenger™ is a chromatography that not only eliminates traces of DNA and proteins but also allows the selective recovery of the mRNA of the correct size. Shorter abortive transcripts as well as longer contaminating mRNA that are produced during in vitro transcription are eliminated. Capped mRNA will be purified by PUREmessenger™, quantified, re-suspended at 1mg/ml (except if otherwise specified) and aliquoted at 50 µl/aliquot (except if otherwise specified) in sterile conditions. It will be sent to you on cooling blocks together with its documentation: formaldehyde/agarose gel documentation picture. The capped mRNA that is sent to you ready-to-use (dissolved in water or the buffer of your choice) is 100% of your mRNA molecule of interest.\n\nCapped mRNA is produced in clean room facilities for research or clinical applications.\nYour benefit\nHighly purified, efficiently capped mRNA that has a superior efficacy compared to standard mRNA produced with in vitro transcription kits and simply purified by precipitation thus contaminated with alternative transcripts and traces of proteins and DNA fragments. The high quality of mRNA is reproduced from batch to batch. This guarantees the consistency of your results. Capped mRNA can be produced for research or for clinical utilisation: "documented" to be used as Active Pharmaceutical Ingredient or GMP-certified.
1087349
One good one:\n\nDNA replication is much more resistant to errors ... so DNA molecules can be *much* longer than RNA and still survive replication.  This supports the stable propagation of a much larger number of genes (tens of thousands of genes) from generation to generation without degradation.
666450
Hello,\nUsually in Eukaryotes, mRNAs-after transcription- get attached to proteins in the ratio \n            mRNA : Protein = 1 : 3 \nThese complexes of mRNA and protein r called informosomes which are very stable. Usually mRNAs get destroyed immediately after translation but informosomes can survive for about 4 weeks!\nHope this information is sufficient
936132
prixel\nzoom quality\nlux
346188
Gene Codes produce sequences\nseguence assembly & analysis can be found on genecodes.com\nHope this will help
1011608
I really like R.  CRAN (the comprehensive R archive network) has packages that might help you out.\n\nTry a Yahoo Search such as:\ncanonical analysis CRAN\nhttp://search.yahoo.com/search?ei=utf-8&fr=slv8-wdgt&p=canonical%20analysis%20CRAN\n\nIt turns up results such as:\nhttp://www.bioconductor.org/CRAN/src/contrib/Views/Environmetrics.html\nhttp://www.bioconductor.org/CRAN/doc/packages/pcurve.pdf#search='canonical%20analysis%20CRAN'
835461
RNA\nRibonucleic acid (RNA) is a nucleic acid polymer consisting of nucleotide monomers. RNA nucleotides contain ribose rings and uracil unlike deoxyribonucleic acid (DNA), which contains deoxyribose and thymine. It is transcribed (synthesized) from DNA by enzymes called RNA polymerases and further processed by other enzymes. RNA serves as the template for translation of genes into proteins, transferring amino acids to the ribosome to form proteins, and also translating the transcript into proteins.\n\nComparison with DNA\nUnlike DNA, RNA is almost always a single-stranded molecule and has a much shorter chain of nucleotides. RNA contains ribose, rather than the deoxyribose found in DNA (there is a hydroxyl group attached to the pentose ring in the 2' position whereas RNA has two hydroxyl groups). These hydroxyl groups make RNA less stable than DNA because it is more prone to hydrolysis. Several types of RNA (tRNA, rRNA) contain a great deal of secondary structure, which help promote stability.\n\nLike DNA, most biologically active RNAs including tRNA, rRNA, snRNAs and other non-coding RNAs (such as the SRP RNAs) are extensively base paired to form double stranded helices. Structural analysis of these RNAs have revealed that they are not, "single-stranded" but rather highly structured. Unlike DNA, this structure is not just limited to long double-stranded helices but rather collections of short helices packed together into structures akin to proteins. In this fashion, RNAs can achieve chemical catalysis, like enzymes. For instance, determination of the structure of the ribosome in 2000 revealed that the active site of this enzyme that catalyzes peptide bond formation is composed entirely of RNA.\n\nand\n\nDeoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the biological development of a cellular form of life or a virus. All known cellular life and some viruses have DNAs. DNA is a long polymer of nucleotides (a polynucleotide) that encodes the sequence of amino acid residues in proteins, using the genetic code.\n\nYou could get more information from the 2 links below...