Identification of promising antigenic components in latent fingermark residues

An analysis of latent fingermark residues by Sodium-Dodecyl-Sulfate PolyAcrylamide Gel Electrophoresis (SDS-PAGE) followed by silver staining allowed the detection of different proteins, from which two major bands, corresponding to proteins of 56 and 64 kDa molecular weight, could be identified. Two other bands, corresponding to proteins of 52 and 48 kDa were also visualizable along with some other weaker bands of lower molecular weights. In order to identify these proteins, three antibodies directed against human proteins were tested on western blots of fingermarks residues: anti-keratin 1 and 10 (K1/10), anti-cathepsin-D (Cat.D) and anti-dermcidin (Derm.). The corresponding antigens are known to be present in the stratum corneum of desquamating stratified epithelium (K1/10, Cat.D) and/or in eccrine sweat (Cat.D, Derm.). The two major bands were identified as consistent with keratin 1 and 10. The pro-form and the active form of the cathepsin-D have also been identified from two other bands. Dermcidin could not be detected in the western blot. In addition, these antibodies have been tested on latent fingermarks left on polyvinylidene fluoride (PVDF) membrane, as well as on whitened and non-whitened paper. The detection of fingermarks was successful with all three antibodies

Détecter et reconnaître

La détection des traces pertinentes, pas toujours visibles, est le défi auquel le scientifique qui examine un champ d'investigation est systématiquement confronté : il cherche parfois des quantités infimes de matière qui dessinent des crêtes papillaires ou qui lui permettront d'extraire un profil d'ADN. Il cible ses recherches lorsque sur le lieu d'un incendie, l'odeur peut le diriger vers les restes d'un produit inflammable, lorsqu'il extrait des traces numériques pertinentes de gigantesques quantités d'informations ou lorsqu'il teste spécifiquement si une personne a consommé un produit. Le projet d'augmenter simultanément la capacité de détecter la présence de traces latentes et de reconnaître ce qui peut le mieux expliquer une présence ou une action combine nécessairement à la fois le développement de nouvelles techniques et leur intégration dans une approche globale du champ d'investigation dont les fondements sont encore à consolider

Fingermarks as a new proteomic specimen: state of the art and perspective of in situ proteomics

For at least the first three decades since its advent, proteomics has exclusively largely belonged to a clinical, diagnostic, or fundamental biology context. However, the range and the significance of information that proteomes can disclose have led this discipline to be also applied to forensics, ranging from human identification from hair samples, identification of bodily fluids, and microbial forensics to doping investigations. Fingermarks are a relatively new specimen for proteomic studies with any form of proteomic investigation only appearing in 2012 with the analysis of intact peptides and small proteins in situ published by the research group at Sheffield Hallam University. It was not until 2015 that further developments allowed bottom-up proteomics to be also applied directly in situ. While in situ proteomics of fingermarks has many advantages, encompassing simplified sample preparation protocols, speed and the opportunity to perform molecular imaging analyses, this area remains under-investigated. This is probably due to the unique challenges of working with fingermark specimens. The relatively low protein content and the predominantly eccrine origin of fingermarks have been shown to severely impact protein detection at least when the “intact” protein approach is used both in full scan and using a top down approach. In this chapter, advantages, application, challenges and perspective of in situ fingermark proteomics are discussed and compared with classic approaches