COT HUMAN DNA FLUOROMETRIC GRADE

General description

COT Human DNA is prepared from human placental DNA by shearing, denaturing, and reannealing under conditions that enrich highly repetitive elements. It can be used to suppress cross-hybridization to human repetitive DNA when human DNA probes are hybridized in situ. General applications are FISH and DNA microarray hybridizations such as comparative genome hybridization as well as all applications where complex human DNA is used as a target or probe during hybridization experiments.

Application

COT Human DNA is used in the following applications:

• Nucleic acid labeling and detection
• DNA Microarray applications such as comparative genome hybridization and sequence capture
• Complex hybridization of human nucleic acids like FISH

In microarray applications, COT Human DNA is used in hybridization solutions to block repetitive DNA sample sequences from nonspecific hybridizations. In filter and other hybridization techniques, COT Human DNA is also used in pre-hybridization solutions to inactivate nonspecific target binding sites. In all applications customers would like to suppress nonspecific signals most efficiently. The scientific field targeted with this product is for scientists interested in the analysis of genomic variations within the human genome.

Features and Benefits

• Improve specificity by blocking unspecific nucleic acid motifs using high concentrations of double-stranded, repetitive, human DNA.
• Achieve consistent and reliable results using fluorometrically quantified COT Human DNA, for preferentially detecting dsDNA.
• Use COT Human DNA that has been tested using DNA microarrays and comparative genome hybridization (CGH).

Repetitive elements (IRS) present in a probe (e.g., cosmids, YACs, chromosome painting probes) generate nonspecific hybridization signals that are distributed over the whole chromosome or genome. To ensure specific hybridization of the probe to the chromosomal target site (e.g., single-copy sequences or low-copy repeats), the probe must be denatured in the presence of excess unlabeled COT Human DNA. COT Human DNA serves as a competitor. In a subsequent pre-annealing step, the repetitive probe elements rapidly hybridize to excess repeats in the COT Human DNA, while most of the specific probe sequences remain single-stranded, and can thus be hybridized to their chromosomal targets. This technique is known as chromosomal in situ suppression (CISS) hybridization.

Quality

The concentration of the COT Human DNA, Fluorometric Grade, is accurately measured to provide a consistent 1.0 to 1.5mg/ml by fluorometric determination using the Hoechst Dye 33258. Fluorometric analysis ensures a high concentration of repetitive DNA for a consistent, high concentration of active repetitive sequence motifs and optimal suppression of unspecific signals in complex nucleic acid hybridization experiments. Each lot is performance tested in a standard DNA microarray comparative genomic hybridization (CGH) experiment, which makes this product especially suitable for CGH and other DNA microarray applications. COT Human DNA, Fluorometric Grade has a shelf-life of 18 months.
For quality assessment in the CGH application, target sequences located on the X-chromosome are compared in male and female genomic DNA samples. The donor material for this product was tested for HBs antigen and for the presence of antibodies to HIV-1, HIV-2, HCV, and found to be negative.

Sequence

Maximum of length distribution in the range 50 to 300 nucleotides

Physical form

Solution in 10 mM Tris-HCl, 1 mM EDTA, pH 7.2

Storage and Stability

Store at -15–-25 °C. (repeated freezing and thawing does not deteriorate the product)

Other Notes

For life science research only. Not for use in diagnostic procedures.