The human body is a workaholic that involuntarily grinds around the clock to sustain life through breath, blood circulation, and organ functionality. Death doesn’t change that. Our genes continue to work for hours, sometimes even days, after we die. Now, new research published in Nature Communications suggests that certain genes may speed up or slow down in the days following death, and this could help forensic teams better pinpoint the exact time of death. They’ve even invented a software program for it. An international team of scientists at Barcelona's Centre for Genomic Regulation found that genes respond to death in different ways; some by ramping up activity and others by slowing down. The find was a byproduct of the Genotype-Tissue Expression project, a reference database and tissue bank that houses tissue samples from both dead and living patients. It’s a program that will help geneticists and molecular biologists to see how the body makes different cells do different things. Analyzing more than 7,000 samples from 540 donors, the team looked to a genetic material similar to DNA – known as mRNA – that increases when a gene’s activity is increased. Each sample included data on the time between the death of the donor and the preservation of the sample. That information was then inputted into a machine, where the software “learned” the patterns of people and how their genes changed following death. For example, it discovered a decrease in activities involving DNA production, immune response, and metabolism. However, it found an increase in stress response for a person who had died six hours before preservation. The majority of these changes occur between seven and 14 hours after death, before appearing to stabilize. The machine’s algorithm takes those distinct patterns of increases and decreases in gene activity over time into account, backtracking them to the time of death. Of course, the machine isn’t perfect, but it is accurate to within an hour and that's pretty good considering current methods. In modern forensic analysis, the time of death is a window of time from the moment of death until the corpse is discovered. It’s known as the postmortem interval (PMI) and it’s determined by some seemingly archaic methods: body temperature, rigor mortis, stock of insects present in the corpse, and muscle responses from electrical and chemical stimulation. The discovery has major implications for forensic analysis. “This information helps us to better understand variation and also it allows us to identify the transcriptional events triggered by death in an organism," said lead author Pedro G. Ferreira from the University of Porto in Portugal. Being able to pinpoint precisely when a person died is a first step in harnessing gene activity for forensics, and could provide more accurate evidence in criminal cases. Source
