Trending Science: ‘Undead’ genes come alive days after death

Researchers from the University of Washington, Seattle, have discovered that genes in animals remain ‘turned on’ days after death, possibly opening the door to new and better ways for preserving donated organs for transplantation and more accurate methods of determining when murder victims were killed.

Led by microbiologist Peter Noble, the research team wanted to test a new method they had developed for calibrating gene activity measurements. Following research they had undertaken 2 years ago on the abundance of microbes in different human organs after death, they decided to apply their method to post-mortem samples. ‘It’s an experiment of curiosity to see what happens when you die,’ Noble commented. The paper based on the outcomes of this research is currently being peer-reviewed for publication.

Noble and his colleagues extracted and measured messenger RNA (mRNA) levels in the tissue of recently deceased mice and zebrafish. As mRNA plays an important role in gene expression, higher levels of this molecule should indicate more genetic activity. The research team were able to describe over 1 000 genes that ‘stayed alive’ post-mortem. A total of 515 mice genes continued to operate for up to two days, whilst 548 zebrafish genes remained functional for an entire four days after death.

One of the most surprising findings was that hundreds of genes actually fired up - boosting their activity - within the first 24 hours after death. Noble suspects that many of them might have been suppressed or shut off by a network of other genes when their host was alive, and only after death were they free to ‘reawaken’.

The team also found that many of the genes that persisted post-mortem are typically active during embryonic development, which led them to theorise that, on a cellular level, newly developing lifeforms might share a lot in common with degenerating corpses. They also found that several genes that promote cancer became more active following death. This could explain why people who receive organ transplants from the recently deceased have a higher risk of cancer, although this has long been attributed to the immunosuppressive drugs transplant patients are typically prescribed.

In an accompanying paper, Noble and two of his colleagues demonstrated another possible use for gene activity measurements, showing that they can provide accurate estimates on the actual time of death. Estimating the time of death is crucial for criminal investigations but this process is mostly done using non-biological factors (for example, the last SMS sent or call made on the victim’s mobile phone). Following Noble and his colleagues’ discoveries on gene activation after death, there is now the real possibility of being able to biologically affirm the actual time of death, which will greatly benefit forensic and criminal investigations.

Source:http://cordis.europa.eu/news/rcn/125659_en.html?isPermaLink=true?WT.mc_i...