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Total DNA isolation protocol

The procedure is suitable for all types of tissues from a wide variety of animal, blood, plant species and soil. All DNA extraction steps are performed at weak acid pH (HEPES/MOPS free acid) and optionally with hot chloroform for 'difficult' samples, and at room temperature.
The following protocol is designed for small and large tissue samples (tissue volume 100-200 μl).
Note that isolating genomic DNA not requires gentle mixing because the DNA not be sheared by vortexing.

CTAB method for DNA extraction protocol

  • CTAB solution: 1.5% CTAB, 1.5 M NaCl, 10 mM Na3EDTA, 0.1 M MOPS-acid;
    100 ml: 1.5 g CTAB, 2.1 g MOPS-acid, 2 ml 0.5 M Na3EDTA, 30 ml 5 M NaCl;
  • Chloroform-isoamyl alcohol mix (24:1);
  • 100% isopropanol (isopropyl alcohol, 2-propanol);
  • 70% ethanol;
  • Fresh 1xTE (1 mM EDTA, 10mM Tris-HCl, pH 8.0);
  1. 2 ml Eppendorf Safe-Lock microcentrifuge tube with tissue sample and glass ball (6 mm), grind in the MM300 Mixer Mill for 2-10 min at 30 Hz.
  2. In 2 ml tube with mechanically disrupted seeds/leaves/herbarium or DNA solution (CTAB purification) add 1 ml CTAB solution buffer, mix in the MM300 Mixer Mill for 2 min at 30 Hz and incubate the samples at 55-60°C during 1-2 hours.
  3. Spin at maximum speed in a microcentrifuge for 2 minutes, transferred the entire clarified solution to a new 2 ml microcentrifuge tube contains an equal volume of chloroform.
  4. Mix very well for 5 minutes in the MM300 Mixer Mill at 30 Hz; optionally ('difficult' sample): and incubate the samples at 60°C during 60 min.
  5. Spin at maximum speed in a microcentrifuge for 2 minutes, transferred the upper aqueous layer to a new 2 ml microcentrifuge tube which contains 700 μl 2-propanol, vortex well and centrifuge the tubes at maximum speed in a microcentrifuge for 2 minutes.
  6. Discard supernatant and wash pellet by adding 1.8 ml 70% EtOH, vortex very well. Centrifuge at maximum speed for 2 min and discard ethanol.
  7. The DNA pellet do not dry and dissolved immediately in 300 μl 1xTE, pH 8.0 at 55-60°C for 5-10 minutes.

CTAB method for DNA extraction protocol from difficult tissues (high levels of secondary metabolites or polysaccharides), herbarium and soil

  • CTAB solution: 1.5% CTAB, 1.5 M NaCl, 10 mM Na3EDTA, 0.2 M MOPS-acid;
    100 ml: 1.5 g CTAB, 4.2 g MOPS-acid, 2 ml 0.5 M Na3EDTA, 30 ml 5 M NaCl;
  • Chloroform-isoamyl alcohol mix (24:1);
  • 100% isopropanol (isopropyl alcohol, 2-propanol);
  • 1xTE (1 mM EDTA, 10mM Tris-HCl, pH 8.0);
  1. 2 ml Eppendorf Safe-Lock microcentrifuge tube with herbarium sample (the sample mass should not exceed 50 mg) and glass ball (6 mm) grind in the MM300 Mixer Mill for 15 min at 30 Hz.
  2. Add 1 ml CTAB solution buffer, mix in the MM300 Mixer Mill for 2 min at 30 Hz and incubate the samples at 60°C during 1-2 hours.
  3. Spin at maximum speed in a microcentrifuge for 2 minutes, transferred the entire clarified solution to a new 2 ml microcentrifuge tube contains an equal volume of chloroform.
  4. Mix very well for 5 minutes in the MM300 Mixer Mill at 30 Hz and incubate the samples at 60°C during 60 min.
  5. Spin at maximum speed in a microcentrifuge for 2 minutes, transferred the upper aqueous layer to a new 2 ml microcentrifuge tube which contains 700 μl 2-propanol, vortex well and centrifuge the tubes at maximum speed in a microcentrifuge for 2 minutes.
  6. Discard supernatant and wash pellet by adding 1.8 ml 70% EtOH, vortex very well. Centrifuge at maximum speed for 2 min and discard ethanol.
  7. The DNA pellet do not dry and dissolved immediately in 300 μl 1xTE, pH 8.0 at 55°C for 5-10 minutes.


Guanidine thiocyanate method for DNA extraction protocol

  • GuTC extraction buffer: 2 M guanidine thiocyanate, 10 mM Na3EDTA, 0.1 M HEPES-acid;
    the final concentration of guanidine thiocyanate may need to optimized for certain plant/animals tissue from 0.5 to 4 M;
  • Chloroform-isoamyl alcohol mix (24:1);
  • 100% isopropanol (isopropyl alcohol, 2-propanol);
  • 70% ethanol;
  • Fresh 1xTE (1 mM EDTA, 10mM Tris-HCl, pH 8.0);
  1. 2 ml Eppendorf Safe-Lock microcentrifuge tube with tissue sample and glass ball freeze at -80°C, grind in the MM300 Mixer Mill for 2 min at 30 Hz.
  2. Add fresh 500 μl GuTC solution buffer (the sample volume should not exceed 20% of lysis buffer), vortex very well and incubate the samples at 60-65°C during 30-60 min.
  3. Add 1.5 volume (600 μl) of chloroform, vortex very well for 1 minute creating an emulsion. Spin at maximum speed in a microcentrifuge for 2 minutes, transferred the upper aqueous layer to a new 2 ml microcentrifuge tube. Repeat this step.
  4. Transferred the upper aqueous layer to a new 2 ml microcentrifuge tube which contains of 500 μl 2-propanol, vortex well and centrifuge the tubes at maximum speed in a microcentrifuge for 3 minutes.
  5. Discard supernatant and wash pellet by adding 1.5 ml 70% EtOH, vortex well. Centrifuge at 14,000 rpm for 2 min and discard ethanol.
  6. The DNA pellet do not dry and dissolved immediately in 300 μl 1xTE, pH 8.0 at 55°C for 10-20 minutes.


Proteinase K method for DNA extraction protocol

  1. In 2 ml Eppendorf Safe-Lock tube with mechanically disrupted animal or plant tissues add fresh 500 μl of extraction buffer (0.8 M guanidine thiocyanate, 10 mM EDTA, 5% Tween 20, 0.5% Triton X-100, 50 mM HEPES-acid*) with 200 μg of proteinase K, vortex very well and incubate the samples at 55°C for several hours or better overnight at 37°-55°C (the longer the better, until dissolve tissue) with occasional vortexing.
  2. Add 700 μl of chloroform, vortex very well for 1 minute creating an emulsion (in the MM300 Mixer Mill at 30 Hz); optionally: incubate the samples at 55°C during 30 min.
  3. Spin at maximum speed in a microcentrifuge for 5 minutes.
  4. Transfer the supernatant into a new 2 ml tube containing 500 μl of 2-propanol and 100 μl 3M Na-acetate, vortex very well, and centrifuge the tubes at maximum speed in a microcentrifuge for 4 minutes.
  5. Discard the supernatant and add 1.8 ml of 70% ethanol into tube and vortex well; centrifuge the tube for 5 minutes at 14000 rpm and again discard the supernatant.
  6. Do not dry DNA pellet and dissolved immediately in 300 μl of 1xTE, pH 8.0 (with RNAse A) at 55°C for 10-20 minutes.

* alternative extraction buffers for proteinase K:

  • 1% SDS, 10 mM EDTA, 50 mM Tris-HCl, pH 8.0;
  • 3 M guanidine hydrochloride, 10 mM EDTA, 5% Tween 20, 0.5% Triton X-100, 30 mM Tris-HCl, pH 8.0;
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