What is the effect of relatively high (0.001 to 0.1 $M$) concentrations of electrolytes in a solution containing DNA from a cultured organism? How would this affect the structure of DNA? For instance, could it change the structure of B DNA to Z DNA and vice versa? I was just having a review on Meselson–Stahl experiment. I wonder why they didn't use Sucrose Density Gradient instead of Salt ( $CsCl$ ) Density Gradient? Does the $Cs^+$ ion (a species with relatively high atomic mass) exert a special effect on the structure of DNA double helix, such as the formation of a coordination complex or by ionic strength as I asked above?