Evaluation of DNA typing as a positive identification method for soft and hard tissues immersed in strong acids

Abstract

a b s t r a c tIdentification of human remains can be hindered by several factors (e.g., traumatic mutilation, carbonization or decomposition). Moreover, in some criminal cases, offenders may purposely adopt various expedients to thwart the victim's identification, including the dissolution of body tissues by the use of corrosive reagents, as repeatedly reported in the past for mafia-related murders.By means of an animal model, namely porcine samples, we evaluated standard DNA typing as a method for identifying soft (muscle) and hard (bone and teeth) tissues immersed in strong acids (hydrochloric, nitric and sulfuric acid) or in mixtures of acids (aqua regia). Samples were tested at different time intervals, ranging between 2 and 6 h (soft tissues) and 2-28 days (hard tissues). It was shown that, in every type of acid, complete degradation of the DNA extracted from soft tissues preceded tissue dissolution and could be observed within 4 h of immersion. Conversely, high molecular weight DNA amenable to STR analysis could be isolated from hard tissues as long as cortical bone fragments were still present (28 days for sulfuric acid, 7 days for nitric acid, 2 days for hydrochloric acid and aqua regia), or the integrity of the dental pulp chamber was preserved (7 days, in sulfuric acid only).The results indicate that DNA profiling of acid-treated body parts (in particular, cortical bone) is still feasible at advanced stages of corrosion, even when the morphological methods used in forensic anthropology and odontology can no longer be applied for identification purposes.

Development of molecular markers to distinguish between morphologically similar edible plants and poisonous plants using a real‐time PCR assay

“…S7). The artificial gastric fluid is a strong acid and has the potential to cause DNA fragmentation 31 . Short amplicons of the primer set such as ArA_ndhA primer (100 bp) could be successful for detecting simulated gastric samples even with 6 h digestion times.…”

Barcoding High Resolution Melting (Bar‐HRM) enables the discrimination between toxic plants and edible vegetables prior to consumption and after digestion

“…We showed that the developed ITS2‐HRM assay can detect DNA from artificially digested samples in artificial gastric juice with high confidence. The artificial gastric fluid is a strong acid and has the potential to cause DNA fragmentation (Robino et al., 2015). More specifically, digestion in the artificial gastric juice after 0 and 1 h did not seem to have any significant effects on the detection of the toxic plant species in the simulated mixtures, indicated by the observed similarities among the melting curve profiles of both species (Figures 2 and 3), despite the observed DNA degradation after 1 h of digestion (Figure S5).…”

Identification of the Remains of an Adult Using DNA from Their Deciduous Teeth as a Reference Sample

“…A complete DNA profile was obtained from only one molar. The efficiency of DNA typing from teeth subjected to various experimental conditions, such as treatment with acids [49] and fire exposure [50,51], has been reported in the literature. In addition, the effect of the duration of the postmortem and postextraction periods in obtaining genetic profiles from the teeth has been analyzed [52,53].…”