Assessment of the efficiency of DNA isolation and profiling applying a temperature-driven method in human remains.

The identification of human remains is of utmost importance in a variety of scenarios. One of the primary identification methods is DNA. DNA extraction from human remains could be difficult, particularly in situations where the remains have been exposed to environmental conditions and other insults. Several studies tried to improve extraction by applying different approaches. ForensicGEM Universal (MicroGem) is a single-tube approach to DNA extraction and a temperature-driven method that could have some advantages with respect to previous techniques, among them, reducing the risk of contamination, not requiring specialized equipment, or several steps to perform. The aim of this study was to assess, for the first time, the efficiency of DNA extraction and quality of STR profiles applying the MicroGem protocol and modifications of this protocol from tooth samples in comparison with automatic extraction (AE). Our results indicated that AE and MicroGem performed similar, though with variability depending on the MicroGem modifications, increasing the DNA yield and STR profile quality when DNA is concentrated with Microcon. These findings demonstrated the efficiency of this methodology for DNA extraction from human remains while also providing a simple and quick technique suitable to apply in a variety of forensic scenarios.

Recovery of DNA from SERATECⓇ immunochromatographic PSA and saliva test strips.

There is an increased use of immunochromatographic test strips to presumptively identify bodily fluids of forensic interest, such as blood, semen, and saliva. Commonly, forensic samples are of low quantities. In the practice of conserving limited samples, it would be ideal to be able to recover the genetic material deposited on these testing membranes. This research aimed to determine whether DNA could be extracted from semen and saliva test strips, which part of the test strip is best to use, and to assess the quality of the DNA recovered. Semen and saliva samples were deposited on SERATEC® PSA Semiquant and Amylase Tests and analyzed. The testing membrane was then removed from the cassette and DNA extraction methods (forensicGEM Universal, forensicGEM Sperm, QIAamp® DNA Mini kit, Monarch® Nucleic Acid Purification kit, and organic extraction) were performed. Quality was evaluated by qPCR and STR analysis. DNA from semen was best extracted using the Monarch® Nucleic Acid Purification kit, while saliva was best extracted using the forensicGEM or QIAamp kits. No significant differences were observed between collection of the sample well pad and testing strip, thus use of the entire strip is encouraged. DNA from semen and saliva was quantifiable with a 1:1000 dilution. DNA quality analysis by qPCR showed that there is no difference in the DNA quality following elution from the test strip. However, degradation was noted in saliva samples and some semen samples by STR analysis. Scientists are encouraged to consider processed test strips for DNA profiling to preserve evidence.

Detection of prostate specific antigen and salivary amylase in vaginal swabs using SERATEC® immunochromatographic assays.

Immunochromatographic assays are used by crime laboratories to conduct simple and quick analyses of bodily fluids. These streamlined tests are ideal for decreasing the sexual assault kit backlog in the United States. A large-scale analysis of the frequency of positive results of amylase and prostate specific antigen (PSA) endogenously found in the vaginal cavity was conducted using the SERATEC PSA Semiquant and Amylase tests. Vaginal swabs were self-collected by participants after 7-10 days of no oral contact or male ejaculation. In this study of 50 participants, 98% were negative for PSA and 92% were negative for amylase. Positive results were confirmed to contain no exogenous DNA by male-specific quantitation, short tandem repeat (STR) typing, and Y-STR typing. These results can be used by crime laboratories to help guide interpretation of immunochromatographic test results from vaginal swabs and aid in decision-making in downstream DNA testing.