Dear Evaline,
Another factor to consider may be PCR inhibition. We have done some work
recently that shows that different PCR targets may be inhibited to
different extents by the same extract. Could it be that the inhibitor
profile is different in teeth and this is causing problems with the
particular mtDNA primers or amplicon targetted?
Mike
Dr. G.M.Taylor,
Windeyer Institute UCL,
46, Cleveland Street,
London W1T4JF.
> Dear Odile, Wera and Carney,
>
>
>
> Thank you for your response to my mail. Your answers are very helpful.
>
>
>
> To give you a bit better idea about my samples I'll explain a bit more
> about them. Currently I'm working on an archaeological project where I
> have three bone samples and nine teeth from the late medievals. Three of
> the teeth and one bone sample give no result at all. But four teeth give
> both autosomal STRs and mtDNA sequences, two teeth give only autosomal
> STRs and the other two bone samples only give mtDNA sequences. I
> sequenced only the first half of HVR1 in two overlapping fragments, with
> maximum fragment length of 154 bp (including primers).
>
> So it is not that I only get mt for bones and auto STRs from teeth, but
> I was still a bit surprised with the result I got from this project.
> Perhaps it is just a stochastic effect, but I heard from other people to
> that they suspect that there might be more mtDNA in bone then in teeth.
> But the explanation that nuclear DNA is better protected then mtDNA also
> makes sense.
>
>
>
> So, again thanks for your help!
>
>
>
> Best regards,
>
>
>
> Eveline
>
> ________________________________
>
> From: Ancient DNA List [mailto:[log in to unmask]] On Behalf Of
> Carney Matheson
> Sent: dinsdag 7 juli 2009 15:50
> To: [log in to unmask]
> Subject: Re: mtDNA in teeth
>
>
>
> Dear Evelina,
>
> I have experienced this once.
>
> The occasion for which I experienced this was when an individual was
> burnt and submerged in petroleum for a while. I suspected that the
> recovery of mtDNA in this case was affected by the hydrocarbons that
> were present and permeated the bones. The tooth root canal was exposed
> to hydrocarbons as we tested and identified their presence. However we
> did not work on the bone from this individual to compare the results.
>
>
>
> So in addition to Odile's and Wera's methodological comments maybe the
> taphonomy of the sample may explain the differential preservation.
>
>
>
> Remember that the nuclear DNA is somewhat protected by the histone
> proteins to between 145-200bp while the mtDNA is fairly exposed with
> only the possibility of the nucleoids (A DNA associated protein found in
> the mitochondria) for protection. However the nucleoids are not spaced
> the same way as the histones. Therefore the protection from the
> nuceloids does not provide specific fragment sizes, thus the
> fragmentation can be random. There has been some research published on
> the protection of nucleoids to X-ray's and Hydrogen peroxide amongst
> other agents.
>
>
>
> Carney Matheson
>
>
>
>
>
> Dr. Carney Matheson
>
> Associate Professor
>
> Department of Anthropology
>
> Department of Biology
>
> Paleo-DNA Laboratory
>
> Lakehead University
>
> 955 Oliver Rd.
>
> Thunder Bay
>
> P7B 5E1, ON, Canada
>
>
>
> School of Social Science (Adjunct)
>
> University of Queensland
>
> St Lucia, 4072, QLD, Australia
>
>
>
>
>
>
>
>
>
>
>
> From: Ancient DNA List [mailto:[log in to unmask]] On Behalf Of
> Eveline Altena
> Sent: July 6, 2009 6:24 AM
> To: [log in to unmask]
> Subject: mtDNA in teeth
>
>
>
> Dear colleagues,
>
>
>
> At our lab we have the idea from experiences with both forensic and
> archeological human samples that there is much less mtDNA present in
> teeth then in bone. We think so because sometimes we can get nuclear DNA
> from teeth but no mtDNA (or we get mtDNA from bones but no nuclear DNA).
> Even though we use very sensitive multiplex PCR kits for forensic cases
> (eg Powerplex16 form Promega).
>
>
>
> I have heard from two other labs that they have the same experiences,
> but I am not aware of articles that have tested this or where this is
> discussed. Does anyone know of such an article or does anyone have the
> same experiences?
>
> Best regards,
>
>
>
> Eveline Altena
>
>
>
> PhD student ancient human DNA research
>
> Forensic Laboratory for DNA Research
>
> Leiden University Medical Center
>
> PO Box 9600
>
> 2300 RC Leiden
>
> The Netherlands
>
> phone: +31 (0)71 526 9540
>
> fax: +31 (0)71 526 8278
>
>
>
>
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