Journal: PLoS ONE
Article Title: Atomic Scissors: A New Method of Tracking the 5-Bromo-2?-Deoxyuridine-Labeled DNA In Situ
Figure Lengend Snippet: Copper(I) treatment produces short gaps with phosphate groups at the 3′ end. A ) TdT was used to incorporate Alexa-dUTP at the 3′ end of the gaps. A strong signal is observed only after the pre-incubation of cells with exonuclease III or SAP. The model shows the situation after the action of SAP in the case of double-stranded DNA with several gaps. Although the phosphate groups are shown also at the 5′ end of the gaps, it is not clear whether they are present there. Therefore, the action of SAP is shown for 3′ phosphate groups exclusively. Bar: 20 µm. B ) DNA polymerase I, Klenow fragment and Klenow fragment Exo- were used to incorporate Alexa-dUTP at the gap sites produced by monovalent copper. Only DNA polymerase I produced a strong signal. When incubation with exonuclease III preceded the polymerase step, a strong signal was observed also in the case of both Klenow fragments. The model shows the action of DNA polymerase I at the sites of created gaps. Both 3′-5′ proofreading activity enabling hydroxyl group formation and 5′-3′ exonuclease activity (for the sake of simplicity, the excised nucleotides are not shown in the model) enabling nick translation are necessary. As no ligase activity was present, nicks at the ends of the labeled chains persisted (arrows in the model picture), although it is not apparent. Bar: 20 µm.
Article Snippet: Enzymes used These enzymes and condition were used: Terminal deoxynucleotidyl transferase (TdT; 2 U/µl, 10 minutes, 37°C, Fermentas), buffer for TdT, 0.05 mM dATP, dGTP, dCTP and 0.05 mM Alexa Fluor® 555-aha-2′-deoxyuridine-5′-triphosphate (Alexa-dUTP); DNA polymerase I (0.2 U/µl, 10 minutes, RT, Fermentas), buffer for DNA polymerase I, 0.05 mM dATP, dGTP, dCTP and 0.05 mM Alexa-dUTP; Klenow fragment (0.2 U/µl, 10 minutes, RT, Fermentas), buffer for the Klenow fragment, 0.05 mM dATP, dGTP, dCTP and 0.05 mM Alexa-dUTP; Klenow fragment Exo- (0.2 U/µl, 10 minutes, RT, Fermentas), buffer for the Klenow fragment Exo-, 0.05 mM dATP, dGTP, dCTP and 0.05 mM Alexa-dUTP; Exonuclease III (1 U/µl, 30 minutes, RT, Fermentas), buffer for exonuclease III; Exonuclease λ (0.1 U/µl, 30 minutes, RT, Fermentas), buffer for exonuclease λ; Shrimp alkaline phosphomonoesterase (phosphatase; SAP; 1 U/µl, 20 minutes, 37°C, Fermentas), buffer for SAP.
Techniques: Incubation, Produced, Activity Assay, Nick Translation, Labeling