Date of Award
Fall 12-27-2021
Document Type
Thesis
Degree Name
Master of Science (MS)
Department/Program
Forensic Science
Language
English
First Advisor or Mentor
Mechthild Prinz
Second Reader
Nicholas Petraco
Third Advisor
Grace Axler-DiPerte
Abstract
Contact traces are an important part of DNA casework, but the probative value of any identified associations depends on the possibility of passive transfer. There is known individual variation in DNA left behind during contact, this DNA shedding propensity has an effect on whose DNA is detected. This study evaluated this variability using a cell staining approach. Volunteers were asked to deposit a fingerprint on a clean glass slide, then wash their hands and deposit a second fingerprint after a 30-minute wait without touching anything. Three sets of samples were collected over three consecutive weeks. Fingerprints were stained with a fluorescent cell dye (PromegaTM Diamond Dye) and signals were scored under a fluorescent microscope.
The cell staining method worked well and gave clear signals. Cell counts showed high variability across donors (n=24), as well as across the three collection events. Overall, washed hands had significantly lower cell counts than unwashed hands. The data did not show a significant difference between male and female cell counts. Reproducibility in individuals for separate collection events was low for unwashed hands and more consistent for washed hands. This is expected, since sample collection after handwashing and inactivity prevents variability due to external factors. Washed hands showed a wide range of cell counts, and high variability between individuals which reflects differences in shedding propensity, but the distribution seemed continuous. There was no correlation between cell counts and resulting DNA concentrations, which could be due to the presence of cell free DNA.
Recommended Citation
Small-Davidson, Natalee, "Reproducibility of Individual DNA Deposits detected through Cellular Fluorescence" (2021). CUNY Academic Works.
https://academicworks.cuny.edu/jj_etds/200
Included in
Biotechnology Commons, Forensic Science and Technology Commons, Molecular Biology Commons