Successful direct STR amplification of hair follicles after nuclear staining

Hairs are commonly encountered at a crime scene through natural shedding (telogen) or trauma such as during an assault (anagen). The forcible removal of anagen hairs results in retention of the root sheath and therefore the potential for DNA evidence. Telogen hairs lack a root sheath and do not provide a good source of DNA. Microscopy may be performed on all hair samples to detect whether there are cells adhering to the proximal tip to determine if there is a chance of success from subsequent DNA profiling. To aid in improving the microscopy, we report of the staining of hair roots using a range of dyes (SYBR1 Green I, DiamondTM Nucleic Acid Dye, GelGreenTM, EvaGreenTM and RedsafeTM) and subsequent results from DNA profiling. Results showed that nuclei were visualized using all the dyes except for GelGreenTM. The hairs were then directly amplified and all samples produced an STR profile that met requirements for uploading to a DNA database. The staining procedure conducted before direct amplification had no or little effect on the PCR and electrophoresis of the STR fragments. These results show that these nucleic acid binding dyes can be used as a preliminary assessment as to the viability of the sample (number of nuclei present) for STR analysis.