Forensic DNA analysis is typically used to target a single organism that is only one component of a more diverse biological sample, e.g., human DNA. Forensic samples can be considered a type of environmental sample and will routinely consist of many organisms. Those non-targeted organisms may hold significant value and may be used to provide probative information about the potential crime or event of interest. Further, these organisms can be used to establish a geolocation database which can help track items and organism of interest from their origin.
During her poster presentation at ISHI 32, Amber Vandepoele will present a research project focusing on optimizing a method for the phylogenetic differential separation of mixed samples; specifically, the separation of bacterial, plant, and human cells in a mixed sample.
Briefly describe your work/area of interest.
My research interest is in forensic DNA analysis. DNA analyses typically focus on single target organisms in a sample, for example human DNA. However, forensic samples, a type of environmental sample, will routinely consist of many organisms, all of which may provide probative information about the potential crime or event of interest. My research project focuses on the optimization of a novel method to separate a mixed sample of bacterial, plant, and human cells by its cellular components. This separation method will allow complex sequencing-based analysis to be interpreted more easily, and thereby maximizing the amount of genetic information that can be gleaned.
We have been able to successfully separate human from bacterial cells and are currently working on adding plant cells to the existing separation protocol. On a daily basis I run the separation protocol which uses size exclusion filtration and differential chemical lysis to separate the different cell types followed by manual DNA extractions. After the DNA is extracted, I run quantitative PCR on the samples using species specific primers to determine the efficiency of the protocol. I often find myself doing variations of the protocol and doing small projects in order to further optimize our protocol and tackle any new problems that arise.
Key collaborators in this project are Dr. Michael Marciano and Molly Dunegan. Dr. Marciano is my PI and is the first person I go to when the troubleshooting process starts. He allows me to largely work independently and think through problems on my own while also helping and providing guidance when I need it. Molly Dunegan started this research project during her time as a graduate research student in the Marciano lab. Without Molly’s contributions to the project, we would not be where we are today. She is also someone I can still go to now and ask for guidance when I need it.
The results of our project show the successful separation of bacteria and human cells. Work is ongoing to optimize a three-organism separation, which includes plant cells.
How did you get interested in this work? Why did this particular project appeal?
I really became interested in this project after getting the opportunity to shadow Molly Dunegan when I was just a first-year student. I knew I was interested in DNA when I got to college, but I was unsure what I wanted to focus my research on. After shadowing Molly for a semester, I knew this project had the potential to have an enormous impact on the DNA analysis field and wanted to continue the research. After Molly graduated, I took over the project and have enjoyed working on it ever since.
Can you summarize the impact of your work for the audience (ISHI attendees and some general forensic enthusiasts)? How might this advance the field?
Knowledge of the type of plant and microbial species present in an environmental sample can provide a wealth of information to investigators. These species can contribute information regarding a location or interaction and aid the investigation of a potential crime. Further, it allows for the proposition of a database to track or identify items/organisms of interest. The implementation of this research into the forensic field would encourage and allow for the analysis of previously overlooked evidence that could be imperative to specific cases.
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