I am extracting DNA from cicada exuviae using ethanol precipitation combined with either NaCl 6M or Ammonium acetate. After DNA extraction, my samples have quite low A260/230 ratio such as in the attached picture. I suspect this might be due to left-over salt in my samples, since I dont use kits or phenol/chloroform/isoamyl in DNA extraction protocol. I proceeded on with PCR using 16S primers but received no bands.

Could you advice what potential contaminants could appear in the samples that prohibit PCR? As well as what could I do to improve this ratio? Thank you so much!

Spectrophotometer measurements of DNA samples

  • $\begingroup$ Are the cultured cells you use in the beginning or tissues? How do you break your cells? $\endgroup$ – Chris Apr 4 '16 at 10:04
  • $\begingroup$ Actually, I used exokeleton, which contains left-over tissues of cicada when it molts. For the lysis, I used 600 ul buffer including Tris 10 mM, pH 7.5, NaCl 400 mM, EDTA 100 mM, and SDS 0.6%, along with 30 ul Proteinase-K. $\endgroup$ – HoaNQ8x Apr 5 '16 at 4:29

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