Examination of the temporal variation of peptide content in decomposition fluid under controlled conditions using pigs as human substitutes

Abstract

Examination of the temporal variation of peptide content in decomposition fluid under controlled conditions using pigs as human substitutes, Forensic Science International (2019),

The impact of environmental factors on the production of peptides in mammalian decomposition fluid in relation to the estimation of post-mortem interval: A summer/winter comparison in Western Australia

“…Correlation between chain length and days post-mortem was most apparent for peptides originating from haemoglobin subunit alpha (r= 0.91 and 0.69 for summer and winter, respectively). As time progressed, trends towards shorter peptides were apparent (Figures 4a and 5a), in agreement with our previous findings [32]. In contrast, for troponin C2 a trend towards larger peptides was observed as time progressed (r= 0.84), however the relative standard deviations for the calculated means were large (21.2%)( Figure 5f).…”

“…Of the six proteins identified across both trials, five were detected in our previous study [32]: creatine kinase, beta-enolase, L-lactate dehydrogenase, haemoglobin subunit alpha, and haemoglobin subunit beta. None of these proteins correspond with the findings of Pittner et al [31,33] (Figure 3).…”

“…The full preparation and analysis of decomposition fluid samples were as described in Nolan et al [32]. Fluid samples were diluted, filtered and loaded onto a Vivaspin 2 10,000 MWCO filter (Sartorius, Australia); this ensured that not only larger peptides were removed from the sample, but bacteria and enzymes responsible for peptide degradation were also eliminated.…”

“…In contrast, studies that have used biochemical approaches have relied upon more robust parameters to assess the rate of decomposition with encouraging results [15,[27][28][29][30][31][32][33]. It is suggested that of the biochemical techniques used to estimate the PMI, measurement of the rate and extent of protein degradation is a promising approach [31][32][33]. Pittner et al demonstrated that the degradation of several skeletal muscle proteins occurred with high reproducibility and at different time points during the decomposition process, allowing for more precise estimations of PMI during the intermediate and late post-mortem stages [33].…”

“…Our previous work, although taking a different analytical approach, demonstrated that blood proteins in decomposition fluid degraded in a regular fashion in the presence or absence of insect activity [32]. These studies were conducted under controlled conditions in a laboratory-based environment, so the applicability of these findings, expressed in ADD, to a field-based forensic setting is yet to be demonstrated.…”