Two strands of DNA are not equivalent as probes in hybridizations at low stringency

Only one of the two complementary strands of a restriction fragment hybridizes under low stringency conditions to a cloned Arabidopsis thaliana genomic DNA fragment. We propose that this effect is caused by the energetic nonequivalence of the two possible mismatched duplexes, resulting from the accumulation of mismatches and extrahelical bases. These mismatches will differ between the two duplexes. The choice of probe strand may therefore be important for the success of heterologous hybridizations utilizing single-stranded probes.