Phenol-chloroform DNA extraction from sand flies 1. Crash Individual sand flies in 0.5 ml lysis buffer (50 mM NaCl , 10 mM EDTA, 50 mM Tris-HCl pH 8). 2. Incubate The sand fly homogenates with 100 ng/ml Rnase at 37℃ for 30 minutes. 3. Incubate The cell lysates with 200ng/ml Proteinase K at 65℃ for 2 hours. 4. Extract the DNA with equal volumes of buffered phenol, Phenol-chloroform- isoamyl alcohol (v/v, 25:24:1) and finally chloroform-isoamyl alcohol (v/v, 24:1). 5. precipitate the DNA with 3-M ammonium acetate and 2.5 volume of 100% ethyl alcohol. 6. wash the DNA pellet with 70% ethanol 7. dry the pellete in speed vacuum centrifuge for 10 minutes. 8. suspend the DNA pellets with 100-µl d oubl disteled, sterile water and store it at -20 for PCR experiments. Guanidine thiocyanate extraction procedure Reagents preparation 1. Guanidine thiocyanate (FLUKA, Switzerland) solution contains 4-M guanidine thiocyanate, 0.1 M Tris-HCl pH 6.4, 0.02M EDTA pH 8 and 1.3 % Triton X-100. 2. Sodium iodide (MERCK, Germany) is prepared as a 6-M solution. 3. Suspend Three grams of silica beads (Sigma) in 25 ml of double distilled, sterile water for 24 hours. 4. Centrifuge The suspension at 12,000 RPM for 5 seconds and remove the supernatant . 5. Add additional 25-ml of double distilled, sterile water and wash the beads for 5 hours using rotator. 6. centrifuge The suspension at 12,000 RPM for 5 seconds and remove the water. 7. Finally, add 30 µl of 1 M of hydrochloric acid (HCl) and autoclave the beads 8. aliquot and store in the dark at room temperature. Washing buffer The washing buffer stock contained; 0.2 M Tris HCl pH 7.5, 1 M sodium chloride, and 20 mM EDTA pH 8. 1. Dilute the washing buffer stock solution 1:9 with double, distilled, sterile water 2. Add an equal volume of 100% ethyl alcohol . 3. Divide the solution into 50-ml tubes and store at 20℃. Procedure 1. ground Each sand fly in 1.5 ml autoclaved and UV radiated microfuge tubes, using a micro-pestle (Ependorph, Germany). 2. suspend each pestle in 0.5 ml 4-M guanidine solution and incubate the samples at 56℃ under gentle agitation. 3. Next day, boil the samples for 10 minuets and centrifuge them at 12,000 RPM for 5 minutes 4. Remove the debris leaving a sand fly tissue pellet. 5. Add 1 ml of 6 M sodium iodide and 10 µl of suspended silica beads to each tube, vortex gently for 5 seconds and incubate on ice for 1 hour, perform gentle mixing every 15 minutes. 6. Remove the supernatant carefully and wash the pellet two times with 500 µl of ice-cold washing buffer. 7. vortex the pellet and centrifuged for 5 seconds at 12,000 RPM. 8. Remove the buffer and wash the pellet one to two times with 100% ethyl alcohol . 9. Remove ethyl alcohol and dry the pellet . 10. Re suspend the DNA in 100 µl of double distilled, sterile water, mix gently and incubated at 56℃ for 1hour. 11. Centrifuge the DNA samples at 12,000 RPM for 5 minutes at room temperature, aliquot the supernatant and store at 20℃ for PCR experiments. |
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