Species Identification Through DNA “Barcodes”

Abstract

Conventional methods for forensic species identification are mainly based on immunological procedures, which have limited applications for old and degraded specimens. The mitochondrial cytochrome b gene sequence has emerged in forensics among molecular methods. Recent investigations in the taxonomic field have suggested that a DNA-based identification system may aid the resolution of animal diversity and classification using sequence analysis and phylogenetic links. Selected gene sequences can be viewed as a genetic "barcode," which is enclosed in every cell, and barcoding is a standardized approach for characterizing species using short DNA sequences as a diagnostic biomarker for organisms. The aim of this study was to evaluate the potential of barcode mitochondrial genes, such as the cytochrome c oxidase sub 1 (COI) and the 16S rRNA gene, as a forensic tool. We developed a new approach for species testing and identification with a singleplex PCR amplification that will be useful not only in criminal casework but also in biosecurity, food authentication, investigation against poaching or illegal trade of endangered species, and wildlife enforcement. Seven fragments ranging from 157 to 541 bp (base pairs) in humans were selected from COI and 16S rRNA genes by different redesigned sets of primers suitable for forensic purposes. The specificity of each primer pair was evaluated with a single PCR reaction on different substrates, and the diversity values were calculated by statistical tests to select a set of markers that could be useful in different caseworks. A case example of forensic species identification is also presented.

DNA barcoding of the Indian blackbuck (Antilope cervicapra) and their correlation with other closely related species

“…This technique uses the mitochondrial region of cytochrome C oxidase subunit I (COI) to provide a strong species-level resolution for diverse wildlife (Linacre & Tobe 2011). The DNA barcode region contains highly conserved sites for primer binding, and it can be used to show interspecific variations (Ferri et al 2009;Eaton et al 2010). This method has been attracting international attention due to its significant role in advancing the taxonomy of life forms and their forensic implications.…”

Forensic botany: species identification of botanical trace evidence using a multigene barcoding approach

“…In order for a region of DNA to be effective as a barcode, it must simultaneously contain enough variability to be informative for identification, be short enough to sequence in a single reaction, and contain conservative regions, which can be used to develop universal primers. A portion of the mitochondrial cytochrome c oxidase I gene sequence is currently being used as a universal barcode in certain animal groups and has been proposed also in the forensic field [21][22][23]. Based on the existing literature, there is currently no available universally usable region, and it is generally agreed that a multilocus approach based on plastid (chloroplast) data is the most effective strategy for species identification and recognition in plants [24][25][26][27][28][29].…”

Barcoding in trypanosomes

“…Reliable: the primer binding sites should be highly conserved and/or multicopy, so the primers are still applicable for field samples that may have suffered a degree of DNA degradation. (Savolainen et al 2005;Ferri et al 2009;Valentini et al 2009;Pečnikar andBuzan, 2014) Valentini et al (2009) discussed the different requirements of DNA barcodes for different users, and highlighted the differences between DNA barcoding 'sensu stricto' and 'sensu lato'. DNA barcoding 'sensu stricto' is favoured by taxonomists and prioritizes standardization of primers with enough variation to elucidate a high level of phylogenetic information.…”