Description_x000D_ General description_x000D_ A ready-to-use solution of high quality double-stranded template DNA isolated from the thymus of male and female calves. The solution is supplied at a concentration of 9 - 12 mg/ml ._x000D_ Application_x000D_ Deoxyribonucleic acid solution from calf thymus is suitable for use as a blocking agent in Southern hybridizations. It was used as negative control in DNA-DNA hybridization experiments using genomic DNA preparations of Vibrio parahaemolyticus and Vibrio alginolyticus. It was used as a standard for DNA quantification by fluorescent assay._x000D_ 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._x000D_ 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._x000D_ 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._x000D_ 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._x000D_ Deoxyribonucleic acid solution from calf thymus has been used in in situ hybridization and microarray hybridization._x000D_ Preparation Note_x000D_ 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._x000D_ Other Notes_x000D_ 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.