Polynucleotide hybridization

Signal The end product observed when a specific sequence of DNA or RNA is detected by autoradiography or some other method. Hybridization with a complementary radioactive polynucleotide (eg, by Southern or Northern blotting) is commonly used to generate the signal. 

Polymetaphosphate 3 Polymorphonuclear leukocytes 26 Polynucleotide(s) 199s, 226-228. See also Nucleic acids, RNA, DNA hybridization 255 hydrazine reactions 254 interactions with ions 218 melting of 255 probes 255... 

In 1961, Jacob and Monod postulated messenger RNA (mRNA) as a short-lived polynucleotide.30 32 33 An abundance of additional evidence supported the proposal. For example, RNA molecules produced after infection of E. coli by bacteriophage T4 underwent hybridization (Chapter 5) with denatured DNA of the bacteriophage. Furthermore, this virus-specific mRNA became associated with preexisting bacterial ribosomes and provided the template for synthesis of phage proteins.34 The experiment provided direct evidence for transcription of mRNA from genes of the viral DNA. 

Keywords Polynucleotide arrays, hybridization, sequencing, DNA chip. 

Osmium tetroxide is an electroactive marker of the polynucleotide chain and is a good probe of the DNA structure since dsDNA is modified by osmium to a much lesser extent than single-stranded polynucleotides. The limit of detection of osmium-labelled DNA was below 5 ng cm-3 after 2 min accumulation time [66]. Adsorptive stripping linear sweep voltammetry of osmium tetroxide labelled DNA at a mercury electrode [66, 67] was shown to be a good sensor for hybridization of DNA. 

T4 polynucleotide kinase (New England Biolabs, Beverly, MA, USA) phenol-chloroform (Gibco BRL, Rockville, MD, USA) 732P-AIP (NEN, Boston, MA, USA) Chroma Spin-10 columns (Clontech, Palo Alto, CA, USA) ExpressHyb Hybridization Solution (Clontech, Palo Alto, CA, USA) 20 x saline-sodium citrate (SSC) and 10% sodium dodecyl sulfate (SDS Biofluids, Rockville, MD). 

Of considerable further interest is the finding of Marmur and Ts o (1961) that the denaturation of DNA in formamide-water mixtures results in the separation of the two polynucleotide strands. An N N hybrid Escherichia coli DNA was treated with 95% formamide at 37°C for 15 min at an ionic strength of 0.01, the formamide was then removed by dialysis, and the DNA was centrifuged in a CsCl density gradient. The presence of two bands of density different from that of the original hybrid indicates that strand separation occurred. It is of considerable practical interest that these conditions are much milder than those required to achieve strand separation in aqueous solution. Whether strand separation occurs also in solutions of DNA in other nonaqueous solvents is not yet determined. 

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