Evaluation of membrane filter methods for DNA-DNA hybridization

Three membrane filter methods for DNA hybridization were compared. In all of them filter-fixed DNA is spontaneously released during incubation. The effect depends largely on the temperature: 40 to 85% of DNA is released at 70 to 80 C; at higher temperatures most of the DNA is released and heterologous DNA relatedness values are unreliable. Only the dimethylsulfoxide filter method (Legault-Démare et al., 1967) can be recommended for the entire temperature and % GC range. The methods of Denhardt (1966) and of Warnaar and Cohen (1966) are not recommended for hybridizations of DNA containing more than 50% GC. Impure DNA yields too low DNA relatedness values.