Pure genomic DNA has numerous applications in molecular biology, including PCR and restriction digestion analysis. The Wizard® SV Genomic DNA Purification System by Promega can extract DNA from cultured cells and animal tissue using either a centrifuge or vacuum. This is a column based kit that can result in high yield, pure genomic DNA in 20 minutes. I have used this kit for the extraction of genomic DNA from untreated and radiation treated MDA-MB-231 and T47D mammary carcinoma cells for subsequent use in a DNA damage ELISA. A thorough protocol for the more complicated extraction of genomic DNA from mouse tails in included in the product insert.
Extraction from cultured cells is easy and this kit requires little preparation. The wash solution in the kit requires addition of 95% ethanol and PBS is the only required material that is not supplied. In my own use, I plated mammary carcinoma cells in 10 cm dishes at 2.5 x 104 approximately 24 hours prior to use. Cells were then washed once with PBS and then cell lysates were obtained by scraping the cells into 150 µL of the kit’s lysis buffer. At this point, lysates can be stored at -70°C for later use. I have used the centrifugation method, whereby whole cell lysates are applied to columns, spun to bind the DNA to the column, washed 4 times with an ethanol based wash buffer and eluted into nuclease-free water. RNase is provided if you choose to add it to the eluted DNA, as occasionally some RNA can be co-purified with the DNA.
Using this kit I have consistently obtained good yields of high purity DNA from cultured cells. DNA was quantified and purity assessed using a Nanodrop quantification system and by running the DNA on an agarose gel. However, if you do not get this result, a highly comprehensive troubleshooting section is included in the product insert. The only issue that I have had with this kit has been column clogging; this is caused when the lysate of too many cells is applied to the column. The manufacturers recommend that no more than 5 x 106 cells should be loaded onto the column. This highlights the importance of plating a consistent and known number of cells for extraction.
PhD Student
The Liggins Institute
University of Auckland