Thanatotranscriptome

The thanatotranscriptome denotes (in the fields of biochemistry, microbiology and biophysics of thanatology and in particular forensic) all RNA from the transcript of the part of genome still active or awakened in the internal organs of a dead body for 24 to 48 hours following the time of the death.[1] · [2] (It was recently shown that in these 48 hours, some genes continue to be expressed in cells, producing the mRNA and that certain genes are expressed again that had been inhibited since the end of fetal development) [3]

DNA microarray used to analyze the expression of human genes left mouse right.

Thanatotranscriptomic Analysis

It can from a serology postmortem characterize transcriptome of tissue particular cell type, or compare the transcriptomes between various conditions experimental.

It can be complementary to the analysis of thanatomicrobiome to better understand the process of transformation of the necromass in the days following the death;.[4]

Characterization and quantification of the transcriptome in a tissue "dead" given and conditions data can identify genes assets, to determine the regulatory mechanisms of Gene Expression and set networks of gene expression.

Analytical Techniques

The techniques commonly used for simultaneously measuring the concentration of a large number of different types of mRNA include Microarray, high throughput sequencing said RNA RNA-Seq.

Scientific History

Clues to the existence of a post-mortem transcriptome existed at least since the beginning of the 21st century,[5] but in scientific publications the word thanatotranscriptome seems to have been first proposed by Javan et al. in 2015;[6]

At the University of Washington, Peter Noble, Alex Pozhitkov and their colleagues recently (2016) confirmed that up to 2 days (48 hours) after the death of mice or zebrafish, many genes still function in their body.[3]
changes in the quantities of mRNA in the body prove that hundreds of genes with very different functions awoke just after death 548 genes have thus awakened after the death of zebrafish and 515 in the laboratory mice.[3] Among the genes which thus awake, there are genes involved in the development of the organism, including genes that are normally activated only in utero or in ovo (in the egg) during fetal development.[3]

Applications

This information could possibly in the future lead to:

  • Construct a definition both more accurate and nuanced phenomenon of "death";
  • More precise time of death by the forensic (or a biologist or veterinarian in an EcoHealth investigation who needs information on hours or causes of poisoning, without the case of a zoonosis for example.
    We are far, but if we come to better understand the steps of this phenomenon in the Human, a coroner could via a "postmortem serology"[7] perhaps in the future, according to the dosage of the mRNA, establish with greater precision the time since death (by hour, even in minutes rather than days, which can be useful for investigations to reconstruct the conditions of death[3]).
  • Illuminate the phenomenon of cell death of apoptosis or the death of a body, and in particular the phenomenon of ischemia (myocardial including[8]) and its process healing or resilience, for perhaps then to facilitate them.
    This gene revival also means remaining in the cells for up to 48 hours after the death of these animals enough energy for activating the cellular machinery.[3] At least part of these genes appear to be genes involved in physiological healing, healing or "auto-resuscitation".[3]
  • Understand cancer. It was found that among the genes reactivated soon after death, some of the genes involved in the process of cancerous (reactivated with a peak of activity reaches about 24 hours after death[3]) ; detailed understanding of this phenomenon could shed light on the phenomenon of carcinogenesis and maybe bring some new elements to better combat.
  • Improving the quality of organ transplants. Indeed, the fact that cancer-related genes are activated after the death in animals is information that leads us to consider the time of organ transplantation to reduce the incidence of cancer in people receiving these transplants.[3] Persons to which was grafted a new liver actually more cancers after treatment than would be statistically normal. This phenomenon was attributed to the diet imposed on them, or immunosuppressive drugs they receive for their body does not reject the transplant.[3] One hypothesis (yet to be verified) is that the cancer genes activated in the liver of the donor may also play a role.[3]
  • Whether there is the same in humans, because previous studies have already shown that in people dead by trauma, heart attack or suffocation, various genes including those involved in cardiac muscle contraction and wound healing, were active more than 12 hours after death.[8] Similarly for gene dental pulp.[9] Some authors in 2015 introduced the concept of "thanatotranscriptome apoptotic"[10]
  • Test another hypothesis is that after death, a rapid decrease of the "suppressor genes" activity (which normally inhibit the activation of other genes, including those no longer needed after the fetal stage) would allow dormant genes wake up, at least for this short period of time.[3]

See also

References
  1. Pozhitkov, A. E., Neme, R., Domazet-Loso, T., Leroux, B., Soni, S., Tautz, D., & Noble, P. A. (2016). Thanatotranscriptome: genes actively expressed after organismal death. bioRxiv, 058305.
  2. Javan, G. T., Can, I., Finley, S. J., & Soni, S. (2015). The apoptotic thanatotranscriptome associated with the liver of cadavers. Forensic science, medicine, and pathology, 11(4), 509-516 (summary).
  3. Williams, Anna (2016) “Hundreds of genes seen sparking to life two days after death (The discovery that many genes are still working up to 48 hours after death has implications for organ transplants, forensics and our very definition of death)”; New Scientist, 21 juin 2016, commentant un article intitulé “Genes get active after death” dont la référence est BioRxiv, DOI: 10.1101/058305; DOI: 10.1101/058370
  4. Javan, G. T., Finley, S. J., Abidin, Z., & Mulle, J. G. (2016) The Thanatomicrobiome: A Missing Piece of the Microbial Puzzle of Death. Frontiers in microbiology, 7
  5. Javan, G. T., Can, I., Finley, S. J., & Soni, S. (2015). The apoptotic thanatotranscriptome associated with the liver of cadavers. Forensic science, medicine, and pathology, 11(4), 509-516.
  6. Javan, G. T., Kwon, I., Finley, S. J., & Lee, Y. (2015). Biochemistry and Biophysics Reports.
  7. Moreno, L. I., Tate, C. M., Knott, E. L., McDaniel, J. E., Rogers, S. S., Koons, B. W., ... & Robertson, J. M. (2012). Determination of an effective housekeeping gene for the quantification of mRNA for forensic applications. Journal of Forensic Sciences, 57(4), 1051-1058 (summary).
  8. González-Herrera, L., Valenzuela, A., Marchal, J. A., Lorente, J. A., & Villanueva, E. (2013). Studies on RNA integrity and gene expression in human myocardial tissue, pericardial fluid and blood, and its postmortem stability. Forensic science international, 232(1), 218-228 (summary).
  9. Poór, V. S., Lukács, D., Nagy, T., Rácz, E., & Sipos, K. (2016). The rate of RNA degradation in human dental pulp reveals post-mortem interval. International Journal of Legal Medicine, 130(3), 615-619 (summary).
  10. Javan, G. T., Can, I., Finley, S. J., & Soni, S. (2015). The apoptotic thanatotranscriptome associated with the liver of cadavers. Forensic science, medicine, and pathology, 11(4), 509-516 (summary.
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