 |
 |
Hello Natasha, and all I don't know if you are planning on DNA analysis being a part of your project? We are thinking at the moment about how best to preserve wet remains in the field, which can then be used for potential DNA studies, either for plant identification or for analysis of crop domestication and movements. I very much like Angela Schlumbaum et al's review paper for general principles and good examples of the analyses people have done with plant ancient DNA. They recommend that samples for DNA analysis are identified in the field, and treated as DNA samples, rather than general archaeobotanical samples. Take some measures to minimise contamination of the ancient DNA by modern DNA, for instance from pollen in the air, other samples, other strata, etc. DNA degradation is thought likely to be worse in wet remains than dry, due to the effect of hydrolysis on the molecules, but how best to handle the samples in the field to a) stop bacterial and fungal degradation and b) preserve as much as possible of the DNA in the sample? Our thinking at the moment is that fomalin is likely to damage the DNA, based on a number of studies of DNA in museum samples. Alcohol is possibly not as bad, but definitely not ideal. If you want to store in liquid, sterile saline might be the best possibility. Ideally though, we think that drying the samples and getting them cold as quickly as possible seems the best way to go. In the field, desiccants (silica gel or rice) might be the most practical means of drying. Does anyone else have any experiences or views to share on handling waterlogged samples in the field, for the purpose of DNA extraction later? Jay Moore -----Original Message----- From: The archaeobotany mailing list on behalf of Natasha Lyons Sent: Mon 3/24/2008 6:09 PM To: [log in to unmask] Subject: Re: Archaeobotany workshop at Worcester in May Hello folks, I'm writing you from Vancouver, Canada - greetings. I am an archaeobotanist who is entering a project with a local First Nation that has been excavating a large and unprecedented plant processing site. There are both wet and dry site components. I myself have worked only on dry sites and largely with macroremains. My role in the project is to help figure out sampling and processing for the wet site macroremains (and suggest where to sample and arrange for microremain analysis, as appropriate) and to teach members of the Nation to process and analyse these remains. It's a long term ongoing type of project. My questions are very rudimentary with regards to doing work in a wet site context. The matrix is very peaty and I am unsure how to proceed with either sampling or processing (eg. what size of samples to aim for, should we try water seiving before going to the microscope, are there specific techniques for macroscopic analysis of wet plant materials?), though I am gaining ideas from reading the British/European literature. Any help with references or anecdotal experience would be very much appreciated. I will be at the upcoming Society for American Archaeology meetings as well as at the World Arky Congress in Dublin this summer - I'd be happy to buy beers in exchange for knowledge! And of course I can be contacted at this address. Very much appreciated. Sincerely, Natasha Lyons Post-doctoral Fellow, Simon Fraser University Burnaby, British Columbia, Canada E: [log in to unmask] T: 604.871.9822