When a doctor declares a person dead, some of their body may still be alive and kicking – at least for a day or two. New evidence in animals suggests that many genes go on working for up to 48 hours after the lights have gone out. Peter Noble and Alex Pozhitkov at the University of Washington, Seattle, and their colleagues investigated the activity of genes in the organs of mice and zebrafish immediately after death. They did this by measuring the amount of messenger RNA present. An increase in this mRNA – which genes use to tell cells to make products such as proteins – indicates that genes are more active. Noble’s team measured mRNA levels in zebrafish, and in brain and liver samples from mice at regular intervals for up to four days after death. They then compared these with mRNA levels measured at the time of death. As you might expect, overall mRNA levels decreased over time. However, mRNA associated with 548 zebrafish genes and 515 mouse genes saw one or more peaks of activity after death. This meant there was sufficient energy and cellular function for some genes to be switched on and stay active long after the animal died. Hundreds of genes with different functions “woke up” immediately after death. These included fetal development genes that usually turn off after birth, as well as genes that have previously been associated with cancer. Their activity peaked about 24 hours after death. Researchers think that similar process may occur in humans. This discovery could have implications for the safety of organ transplants as well as help pathologists pinpoint a time of death more precisely, perhaps to within minutes of the event. https://www.newscientist.com/articl...s-seen-sparking-to-life-two-days-after-death/
