Zeta-Probe GT (genomic DNA-tested) membranes are designed for sensitive genomic applications. Like the original Zeta-Probe membranes, these are high-tensile-strength cationized nylon membranes that carry a high-density quaternary amine charge. These pliable, flexible membranes are resistant to shrinking, tearing, and becoming brittle during transfer, hybridization, or reprobing procedures.
Zeta-Probe GT membranes bind nucleic acids independently of buffer pH, so they can be used in rapid alkaline Southern or northern blotting techniques as well as in traditional Southern blots. The membranes bind nucleic acids in low-ionic-strength buffers, making electrophoretic transfer of nucleic acids from agarose and acrylamide gels possible. Oligonucleotides as short as 6 bases will bind the membrane through spot application, and those at least 20 bases long will be retained after repetitive hybridization and washing steps.
Every lot of Zeta-Probe GT membranes is functionally tested to ensure that 3 pg of target single-copy factor VIII human DNA can be detected in 5 µg total genomic DNA using a radiolabeled probe. The blots are produced in two different ways prior to hybridization: a standard high-salt (10x SSC) Southern transfer, and a 4 hour alkaline transfer (0.4 N NaOH). In the quality control procedure, 5 and 10 µg of digested human genomic DNA are probed with a factor VIII cDNA clone (single-copy gene probe). This corresponds to actual target sizes of only 1.5 and 3.0 pg of DNA, respectively, which are visualized in an overnight exposure. Bio-Rad quality control procedures also include a 3 day exposure to check for nonspecific background. Zeta-Probe GT membranes are accompanied by a performance certificate that illustrates the lot-specific results and includes an outline of the experiments and a photograph of the original autoradiogram.
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