Biotechnology and Bioinformatics (1+1)

4.2.2. Dot and slot blotting of DNA

Dot or slot blotting analysis was first developed by Kafatos et al. (1979). Dot and slot blotting are simple techniques for immobilizing bulk unfractionated DNA on a nitrocellulose or nylon membrane. Hybridization analysis can then be carried out to determine the relative abundance of target sequence s in the blotted DNA preparations. Dot and slot blots differ only in the geometry of the blot, a series of spots giving a hybridization pattern that is amenable to analysis of by densitometric scanning.

A large number of samples can be applied at once, enabling many different DNAs to be sequenced in a single hybridization experiment. The technique has found many application over the years.

For instance, in genome analysis, information on the gene tic significance of a DNA sequence can often be obtained by using the sequence as a hybridization probe to dot blots of DNA prepared from related species. The rationale is that most genes have homologues in related organisms. For e.g. a coding sequence from the human genome will probably hybridize to related sequences in dot blots prepared from DNA of various mammals.