Dahlquist:DNA Extraction from Human Hair
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Overview
This protocol describes the steps necessary to obtain DNA from human hair for downstream PCR applications.
Recipes
10% Chelex
Makes 10 mL. Store at room temperature.
- Weigh out 1.0 g of Chelex 100 (100-200 mesh, sodium form).
- Add 50 mM Tris to the dry Chelex, to make 10 mL of solution.
- Adjust the pH to 11, using concentrated NaOH.
- Recipe can be increased to make 50 mL.
Note that the Suenaga et al. article uses a 5% solution and does not specify the buffer or pH of the solution. The 10% solution described here from the lab manual for Biology 478 works well.
Protocols
Prepare Hair
- Set heat block to 100 degrees Celsius.
- Pluck 4 hairs from head, making sure follicles are attached.
- Tape down hair end (opposite of follicle end) and trim follicle end of hair to 0.5 cm length with clean scissors.
- Place the trimmed hairs into 0.5 mL microcentrifuge tube.
- Wash with 500 μL of 100% ethanol.
- Add 500 μL of 100% ethanol to the tube.
- Flash spin.
- Pipette off excess ethanol before drying.
- Air dry for 10 minutes in fume hood with cap off until all ethanol has evaporated.
Chelex extraction
- Add 200 μL of 10% Chelex solution to tube with hairs using P1000 tips that had had the tip cut off to make a larger aperture.
- Vortex Chelex solution immediately before pipetting and be sure to pipette from lower down in the tube.
- Add 2 μL of 50 μg/μL Proteinase K (100 μg) to microcentrifuge tube with hairs and mix well.
- Incubate in 55°C water bath for 1 hour.
- Vortex and incubate in a heat block set to 100°C for 8 minutes.
- Spin in a microcentrifuge at 10,000 - 15,000 X g for 2-3 minutes.
- Transfer 100 μL of the supernatant to a 1.5 mL microcentrifuge tube.
- Use supernatant immediately for PCR or store at -20°C.
Next Steps
References
This protocol was adapted from: