While I am away this week, I decided to pick an easy topic to write about: my own. I started independent research working with my advisor in 2013 while I was working towards my masters degree in forensic science. Mass disasters are events because they typically result in mass casualties in less than ideal situations, where loss of facilities and/or electricity can happen. Then we are posed with the question about what do we do with the bodies. As remains are left to decompose, DNA is degrading because it is exposed to heat, humidity, and/or UV damage. So we wanted to see if there was a way to easily collect and preserve DNA samples in heat and humidity for later disaster victim identification (DVI). We collected decomposing skin and muscle from three cadavers at different stages of decomposition to evaluate room temperature tissue preservatives over a span of three months of storage. Besides preserving the DNA in tissues at room temperature, we wanted to see if these preservatives would lyse the cells and release nuclear DNA into solution, which would make DNA analysis faster by removing the tissue lysis step that takes hours to several days. We had success obtaining DNA from the tissue and liquid preservative for up to three months storage from 4 out of the 5 preservatives; however, the quantity and quality of DNA varied. The manuscript just got accepted this summer. My second project, although my first published manuscript, was a collaboration project with a group of scientists in Australia. We evaluated these same 4 preservatives that facilitated leaching of DNA from tissues for direct polymerase chain amplification (PCR). Because the DNA is suspended in solution, an aliquot of sample can be added directly to amplification reagents and amplified, thereby skipping extraction and quantitation all together. This type of analysis is commonly performed on DNA reference samples due to its efficiency and cost effectiveness. My next project is combining these two projects and testing even more methods to collect, preserve, and analyze DNA in decomposing tissue samples in hopes of making recommendations on the best, cheapest, fastest way to process DNA for DVI purposes or crime scene field-work.
References:
1) Sorensen A, Rahman E, Canela C, Gangitano D, Hughes-Stamm S. Preservation and rapid purification of DNA from decomposing human tissue samples. FSI:Genetics 25 (2016) 182-190.
2) Sorensen A, Berry C, Bruce D, Gahan M E, Hughes-Stamm S, McNevin D. Direct-to-PCR tissue preservation for DNA profiling.
References:
1) Sorensen A, Rahman E, Canela C, Gangitano D, Hughes-Stamm S. Preservation and rapid purification of DNA from decomposing human tissue samples. FSI:Genetics 25 (2016) 182-190.
2) Sorensen A, Berry C, Bruce D, Gahan M E, Hughes-Stamm S, McNevin D. Direct-to-PCR tissue preservation for DNA profiling.
This is super interesting. I work at the body farm as well, but I deal with the bacteria side of it. I like reading about things other people can do out there as well. I know we need as many bodies as we can get to make our data more accurate, but in your situation it might be different because you're working with DNA. Do you think it would be helpful if you were to collect skin and muscle from more than 3 cadavers?
ReplyDeleteIdeally you would have as many cadavers as possible due to natural human variation. However, even with a grant this is all that we could afford to do because the kits that we used for DNA quantitation and STR analysis are really, really expensive! I've collected from three more cadavers since these projects and we're using all six for one of our smaller studies.
DeleteThis research could be useful for more than just DVI, it could aid in criminal investigations to ensure DNA samples do not degrade before analysis. I hope your research bears fruit, and you can obtain more grants to pursue this further.
ReplyDeleteI also do research at the body farm, mostly on post mortem interval. It is cool to hear about other projects going on! You talked about how the decomposing bodies are subjected to heat, humidity, and UV damage. Do you think that the DNA would be damaged with prolonged exposure to water? Such as victims of hurricanes or tsunamis, as these are disasters your techniques might be useful in.
ReplyDeleteIt's great that STAFS is getting their name out there because their research is very unique and beneficial!
DeleteYes, we considered that. We stored the tissues in preservatives with heat and humidity up to three months. We didn't submerge tissues or cadavers in water, if that's what you're asking but the DNA was exposed to less than ideal conditions and we successfully generated full profiles until the DNA degradation due to decomposition was too great.
I'm going to amplify what Chris said, and declare that tropical organismal biology is often done in conditions that make preservation of nucleic acids difficult (heat, humidity, UV, and lack of access to refrigeration). This could be useful to lots of people.
ReplyDelete