Two sets of DNA digestion/ligation reactions were carried out simultaneously. In the
first reaction, 100 ng genomic DNA was digested with 10 U EcoRI (Fermentas, Canada) plus
10 U MspI (Fermentas) in a final volume of 50 μL containing digestion reaction buffer (33
mM Tris-acetate, pH 7.9, 10 mM magnesium acetate, 66 mM potassium acetate