Genomic DNA Purification from Sample on FTA Elute

FTA cards are chemically coated matrices for collecting, storing, and processing nucleic acids in a single device. Samples are collected onto FTA Elute cards, and cards are dried. Discs from FTA Elute are manually removed from sample areas using a coring device, such as a Harris Micro Punch, and the recovered DNA is suitable for PCR or other applications.

Materials

• FTA Elute card or Indicating FTA Elute card
• Harris Micro Punch or Uni-Core Punch, 3.0 mm punch tool
• Heating block or thermal cycler calibrated to 95 °C

Protocol

1. Collect sample and dry

Apply up to 40 µL of liquid sample or crush leaf tissue onto FTA Elute card. Air dry for 3 h at room temperature or 15 to 20 min at 80 °C. The cells are lysed when they contact the chemical coating on the card. Proteins become irreversibly immobilized, and DNA interacts reversibly with the fibers of the matrix.

Card must be completely dry before proceeding to punching and purification.

2. Punch

Use a Harris punch tool to remove a 3.0 mm disc from the dried sample. Place into a 1.5 mL microcentrifuge tube.

3. Rinse the punch

Add 500 µL of sterile water and vortex 5 times. FTA Elute chemicals and cellular debris are washed from the disc; proteins remain bound to the disc.

4. Remove water

Centrifuge briefly and remove rinse water. Use a pipette tip to transfer the washed disc to a clean 0.5 mL microcentrifuge tube.

5. Elute purified DNA

Add 30 µL of sterile distilled water and incubate in a calibrated heating block or thermal cycler at 95 °C for 30 min. After incubating the disc, vortex for 1 min by pulsing the tube 60 times to dislodge the DNA from the matrix. During heating, DNA is denatured and dissociates from the fibers of the FTA Elute card. Proteins and other PCR inhibitors remain bound to the matrix.

6. Centrifuge

Centrifuge the tube to recover the condensation from the top of the tube and to pellet the disc. Withdraw the disc from the solution and store eluted DNA.

7. Perform PCR analysis

Use approximately 2.5 µL of eluted DNA in a 25 µL PCR. Store the remainder of the DNA at -20 °C in aliquots.

It is important to quantitate the amount of purified DNA by either real-time PCR or by fluorescent methods such as OliGreen™. The DNA from FTA Elute is too dilute to be measured with spectrophotometric methods even on a micro-spectrophotometer. The yield and purity will be poor if measured by this method, but be assured that the DNA is of sufficient purity for PCR and other downstream applications.