Sentence:  In contrast with predictions based on the melting temperatures of DNA [12 –14 ], our results show that an increasing percentage of GC base pairs in a long DNA molecule "lowers" the stretching force necessary to locally <WSD>dehybridize</WSD> the DNA backbones in the presence of negative supercoiling densities. 
Meaning of the word marked with <WSD> tags:  To remove hybridization