by Zhaojing Gao and Yang Li,
PhD candidates at Polytechnique School of Montreal
In the worldwide culture, it is not difficult to find legends or fairy tales that explain why people will die. For example, there is a legend in Africa that God commands a discolored lizard to bring the undead characteristic to mankind, while this lizard is dallying the lizards with death information that took actions earlier. As a result, people lose the opportunity to become immortal. Up to now, people are still curious about the mystery of death and try to increase the lifetime.
But recently, a group of biologists at the University of Washington made news: they discovered that some genes from mice and zebrafish remained alive after the death of animals. Biologists Dennis Noble and his colleagues collected samples of blood and organs from the dead zebrafish and mice, analyzed the DNA of fish every two days and the DNA of mice every four days, and focused on the activity of 1063 different genes. 24 hours after the death, they found that hundreds of genes were still in activity and some remain active 4 days later. Many of these genes that are running after death are very useful in emergencies, such as genes that cause inflammatory reactions, genes that activate the immune system, and genes that relieve external stress. This subverts the common view that you are dead when you die. Although some micro-organisms may be alive, the human life will absolutely end as an organism.
The more wonderful thing is still behind. Some genes became alive again after the death, and most of these “undead” genes are related to the embryonic growth and development. In general, when the animals are born, these genes become in dormancy, but they will resurrect after the death of animals.
Does this research provide scientific details for the big events that zombies sneak into the earth and eat careless people’s brain? No. One usage of this research is for organ-transplant, better-understanding what is happening to the organs after death, or for evaluating the quality of the organs by detecting the activity of “undead” genes. The other usage Noble claimed is that we can get accurate estimates of death time, instead of relying on indirect evidence from the dead body, such as last phone call.
By studying death, human-beings can obtain a lot of information about lives. With the discovery of “undead” genes, human-being can have the longest lifetime among vertebrates (more than 400 years, the Greenland Shark).
Pozhitkov A E, Neme R, Domazet-Loso T, et al. Thanatotranscriptome: genes actively expressed after organismal death[J]. BioRxiv, 2016: 058305.
Hunter M C, Pozhitkov A E, Noble P A. Accurate predictions of postmortem interval using linear regression analyses of gene meter expression data[J]. Forensic Science International, 2017, 275: 90-101.