Fig 2.

Representative results of purifying DNA from gel by centrifugation at 10,000 rpm for different time periods. A: PCR products were fractioned in 1% agarose gel (top panel). The 3-kb and 1-kb bands (boxed in the middle panel) were excised out and then purified with glass wool (G) or commercial kit (K) by centrifugation for 5 minutes. The recovered DNA was loaded into a new 1% agarose gel shown in the bottom panel. Comparison of the bottom with the top panels reveals that the DNA recovery rates vary between 30-40% by our estimation, with a very slightly better recovery from the commercial kit. B: The same 1-kb and 3-kb DNA fragments shown in A were PCR-amplified again, fractionized in a 1% gel and purified with glass wool (G) by centrifugation for 10 minutes, resulting in about 50% recovery of the 1-kb and 40% recovery of the 3-kb fragment, respectively. C: A DNA fragment of about 800-bp was PCR amplified and then loaded into two wells of a gel (top panel). The fractionized bands (boxed) were cut out and purified with glass wool (G) or absorbent cotton (C) by centrifugation for 5 minutes. The recovery rates are not significantly different between the two methods, considering that the amount of DNA used for the glass wool method is also slightly more than that used for the cotton method (top panel). D: Four DNA fragments of different lengths were excised (boxed bands) and purified with cotton filter by centrifugation for 10 minutes. The recovery rates vary between 30-70% by our estimation.