Complex sentence: Using restriction enzyme DpnII will remove adapter "J" and another adapter, "N", can be added to the Tester cDNA-Tester cDNA PCR products for another round of denaturation and hybridization, and PCR.
Split into simpler sentences: Using restriction enzyme DpnII will remove adapter "J" and another adapter, "N", can be added to the Tester cDNA bound to Tester cDNA PCR products. Now, another the sample can undergo another round of denaturation and hybridization, and PCR.