sentence: Double-stranded DNA fragments ( ds-DNAs ) were labeled at the 5 ′ end by PCR with commercially synthesized 5 ′ - labeled IRD700 or DY682 ( Eurofins MWG Operon , Germany ) primer and the various templates described in Table 1 , 2.ds-DNAs were purified by electrophoresis in 8 % polyacrylamide gels , electroeluted in 0.5 × TBE ( Biosolve , Netherlands ) , through 10 kDa MWCO ( molecular weight cut off ) dialysis tubing ( Spectra / Por , Spectrum Labs , USA ) , and dried on a Speed Vac .