What do you want to do when you've finished? <a href=" http://www.inwaldpark.pl/tetracycline-hcl-bp-250mg.pdf ">tetracycline medicinenet</a> According to Skinner, exposure to DDT appeared to trigger epigenetic changes in the rats, which occur when environmental factors alter the way DNA is expressed.  The mutation was passed down through the sperm or egg of each rat, which was why the effects of DDT exposure were not visible in the first generation of rats.'