Establishment And Evaluation Of The Technique For DNA Extraction From Hair Shaft

Hair is a non-invasive biological sample that plays an important role in studies of conservation genetics and molecular ecology.The hair shaft contains nuclear DNA(nuDNA)and mitochondrial DNA(mtDNA),but its DNA(especially nuDNA)is present at low levels,and it is difficult for existing extraction methods to obtain DNA needed for downstream experiments.It is limited mainly by incomplete digestion of keratin,inefficient recovery of small fragments of DNA,incomplete pigment removal,and large amounts of residual bacterial DNA.In this study,we established an effective,wide-ranging,and low-costly extraction method to solve the above problems.We extracted DNA from hair shafts of 6 animals including arctic fox(Vulpes lagopus),south china tiger(Panthera tigris amoyensis),wolf(Canis lupus),dog(Canis lupus familiaris),deer(Cervus nippon)and cattle(Bos taurus),conducted quantitative detection of the numbers of nuDNA,mtDNA and bacterial plasmid DNA by qPCR,and used the extracted DNA to perform microsatellite(STR)and SNP typing tests to assess the extraction effect and the availability of the extracted DNA.The main findings are as follows:1.In the total DNA extracted from hair shaft,mtDNA were higher than nuDNA at least three orders of magnitude.2.The nuDNA fragment in the hair shaft could support the PCR amplification of less than 150 bp,and the maximum amplified fragment could reach 250 bp;the mtDNA fragment could support the PCR amplification of more than 1500 bp.3.Conventional hair washing methods didn't completely remove the bacteria attached to the hair shaft,and bacterial DNA was the main component of the total DNA extracted.Treating the hair shaft with 4 mol/L NaOH solution at 65? could effectively remove bacterial DNA with little effect on nuDNA extraction from hair shaft.4.Hair shaft DNA could support the STR and SNP typing of short fragments.The shorter the amplified fragment,the higher the typing success and the correctness,and the SNP typing effect was better than STR.