1. Separate DNA fragments through an LMP agarose gel containing ethidium bromide (0.5 microgram/ml).
2. Detect DNA by irradiating the gel with long-wave ultraviolet light (wave length: 355 - 360 nm).
3. Cut out the region of the gel containing desired DNA. Transfer the gel slice into a microfuge tube.
4. Add to the gel slice about 1-3 volumes of TE. Add 0.3 volume of 3M sodium acetate (pH7).
5. Heat the tube at 65 C. Eventually tap the tube to mix the melted gel and TE.
6. Add about equal volume of phenol saturated with TE. Vortex mix for 30 seconds.
7. Centrifuge for 2 min at room temperature, then for 5 min at 4 C.
8. Transfer the aquaous phase into new tube.
9. Add about equal volume of TE-saturated phenol. Vortex for 30 seconds.
10. Centrifuge for 5 min at 4 C.
11. Transfer the aquaous phase into new tube.
12. Extract the solution with an equal volume of ethylether to remove trace amount of phenol dissolve in the DNA solution.
13. Concentrate DNA with ethanol precipitation.
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