General description

A ready-to-use solution of high quality double-stranded template DNA isolated from herring sperm. The solution is supplied at a concentration of 9 - 12 mg/ml .

Suitable for use as a blocking agent in Southern hybridizations.

Other Notes

DNA in solution will reanneal on standing at room temperature so it is recommended to boil the solution for 10 minutes and then cool on ice for at least 5 minutes prior to use.

Preparation Note

This DNA is phenol-chloroform extracted, ethanol precipitated, and sonicated to produce single-stranded fragments which comigrate with the 587 and 831 base pair marker fragments.

Application

Deoxyribonucleic acid from herring sperm is suitable for use as a blocking agent in Southern hybridizations. It was used in preparation of brain sections of mice for BrdU immunohistochemistry. It was also used for hybridization reaction of dot blot membranes.

Many factors contribute to the signal-to-noise ratio in nucleic acid hybridizations. These factors include the presence of solvent (formamide), hybridization temperature, length of hybridization, volume of hybridization solution, degree and method of agitation, use of blocking reagents, concentration and specific activity of the probe, use of molecular agents to increase the rate of nucleic acid reassociation, and the degree of stringency used during the washing of the membrane.

In order to decrease any non-specific hybridization of the probe to a substrate, blocking agents must be used. Generally, a combination of blocking reagent, detergent, and denatured, fragmented DNA is used to accomplish this. Sigma offers sonicated, denatured DNA from a variety of species for use as a blocking agent in Northern and Southern blotting and other nucleic acid hybridization techniques.