preserving dna

[Catherine Young]

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>To: leps-l at lists.yale.edu
>Date: Fri, 20 Jul 2001 18:05:14 -0600
>From: "Gary Anweiler  Edmonton Alberta Canada" <gganweiler at sprint.ca>
>Organization: Sprint Canada Inc.
>Sender: owner-leps-l at lists.yale.edu
>Subject: Re: preserving dna
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You can in fact use both mitochondrial DNA (mtDNA) and nuclear DNA for
analyses at most taxonomic levels, it really depends on the particular gene
fragment you're using and its relative evolutionary rate etc.  I've
succesfully and quite easily amplified nuclear gene fragments from DNA
extracted from dried specimens.  I haven't heard  that it makes  much
difference whether the gene fragments are nuclear or mitochondrial. Its
interesting to read what Niklas said about chloroform killed specimens, I
must admit that I only heard this information from one source and therefore
may be rather spurious

Cathy Young
University of Tasmania








>I am a novice with the DNA work, but have been informed that relaxing
>specimens is death to DNA, but that preservation in100% EtOH works well.
>
>Something that has not been mentioned is that there are two kinds of DNA
>being worked with these days - mitochondrial for work at the specific and
>population level, and nuclear for higher level phylogentic work. It appears
>nuclear DNA is not as stable at mitochondrial, and needs to be treated with
>more care than the mitochondrial stuff.  For example, I don't think dried
>material is of much use for nuclear DNA work.
>
>Can anyone confirm, correct  or expand on this  ????
>
>Gary
>
>Niklas Wahlberg <Niklas.Wahlberg at zoologi.su.se> wrote in message
>news:5.0.2.1.2.20010720095027.00b48cf8 at mail.it.su.se...
>> Hi all,
>>      Here's my perspective on DNA samples from butterflies. I've been
>> working with it almost daily for the past 4 years and I've extracted DNA
>> from close to 1000 specimens. First of all, I never cut off the wings and
>> put the body into the freezer, I extract the DNA from two legs (or one if
>> it's a big one), leaving the rest of the specimen unharmed and maximally
>> useful for taxonomic purposes (if necessary!). I store the extracted DNA
>in
>> the freezer (enough for 50-200 PCRs depending on the freshness of the
>> specimen). As far as I'm aware, water itself has not harmed my extracts.
>> Many of my extracts are from dried specimens that colleagues and friends
>> have sent from around the world. These can be tricky and this is where
>> water can be a problem, through humidity. Specimens stored even briefly in
>> humid conditions are generally useless for DNA work (this obviously
>applies
>> to specimens relaxed in a humid box for spreading). The reason is most
>> likely that bacteria and fungi (moulds) get into the butterfly and
>> basically have a party, ie eat up anything and everything organic
>including
>> DNA. I've been thinking of experimenting with different kinds of relaxing
>> procedures to see whether some procedure would be less harmful to DNA, but
>> I haven't had the time yet.
>>     As for storing specimens for future possible analysis, I reiterate
>what
>> Catherine said in a previous post. Keep them frozen (the colder the
>> better). Pure ethanol (70% ethanol is not good enough) is also an option
>if
>> there is no freezer available. Drying specimens quickly works wonderfully
>> if the specimen will be processed within 1-2 months of being killed. I
>> haven't noticed any effects of the way a butterfly was killed (chloroform
>> is used routinely in DNA extractions, so I can't see why it should destroy
>> DNA) on the quality of DNA.
>>     I envision future holotypes of new species having their DNA extracted
>> from a leg or two, with the DNA info complementing the more visible info.
>> With the way things are going now, who knows, maybe in 20 years we will be
>> sequencing the entire genome of new species routinely! I think it is worth
>> preserving tissue (two legs...) from new taxa now, so that in the future,
>> we can get even more information about what these beautiful creatures
>> actually are.
>>      My two (euro) cents.
>>
>> Cheers,
>> Niklas
>>
>> 
>
>
>
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