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GelGreen is an intercalating nucleic acid stain used in molecular genetics for agarose gel DNA electrophoresis.GelGreen consists of two acridine orange subunits that are bridged by a linear oxygenated spacer.
Contamination by phenol, which is commonly used in nucleic acid purification, can significantly throw off quantification estimates. Phenol absorbs with a peak at 270 nm and a A 260/280 of 1.2. Nucleic acid preparations uncontaminated by phenol should have a A 260/280 of around 2. [2]
Most solutions also have an antioxidant, as oxidized phenol damages the nucleic acids. For RNA purification, the pH is kept at around 4, which retains RNA in the aqueous phase preferentially. For DNA purification, the pH is usually near 7, at which point all nucleic acids are found in the aqueous phase.
"Most agarose gels are made with between 0.7% (good separation or resolution of large 5–10kb DNA fragments) and 2% (good resolution for small 0.2–1kb fragments) agarose dissolved in electrophoresis buffer. Up to 3% can be used for separating very tiny fragments but a vertical polyacrylamide gel is more appropriate in this case.
Transcription-mediated amplification (TMA) is an isothermal (performed at constant temperature), single-tube nucleic acid amplification system utilizing two enzymes, RNA polymerase and reverse transcriptase. "Amplification" means creating many more copies of a strand of nucleic acid than was present at first, in order to readily detect it or ...
Cresyl violet stained partial brain section of a Macaque. It is used in biology and medicine as a histological stain. Cresyl violet is an effective and reliable stain used for light microscopy sections. Initially, tissue sections are "defatted" by passing through graded dilutions of ethanol. Then, rehydrated by passing back through decreasing ...
A further explanation of how DNA binds to silica is based on the action of guanidinium chloride (GuHCl), which acts as a chaotrope. [3] A chaotrope denatures biomolecules by disrupting the shell of hydration around them.
Nucleic acids present in the washed (and preferably dried) silica-nucleic acid complexes is eluted into chosen elution buffer such as TE buffer, aqua bidest, and so on. The selection of the elution buffer is co-determined by the contemplated use of the isolated nucleic acid. In this way, pure nucleic acids are isolated from the starting material.