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I am doing some data analysis about gene expression time series. When I plot mRNA produced by P. Furiosus cells irradiated by gamma radiation against the time of extraction, it seems that there is a negative correlation between them. Is it a good result from a biological point of view ?

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$\gamma$-irradiation produces single- and double-strand DNA breaks, depending on the dosage, and activates DNA damage repair pathways like p53. During this time, the cell cycle arrests and most if not all mRNA production ceases. For sub-lethal doses of $\gamma$ rays, I would expect to see newly-produced mRNA levels drop off fairly quickly with time following the initial dose, then possibly begin to ramp up again later as the damage is repaired and the cell cycle arrest checkpoints released.

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  • $\begingroup$ Thank you for your answer MattDmo, but, in this way I still wonder how can be the demage repaired if the production of mRNA in order to produce proteins for DNA repairing is stopped ? $\endgroup$
    – Manuela
    Sep 8 '20 at 18:55
  • $\begingroup$ @Manuela cells accomplish this by pre-making the DNA repair machinery so that the proteins are already present in the cell, they just need to be turned on. $\endgroup$
    – MattDMo
    Sep 8 '20 at 19:00
  • $\begingroup$ Ok, so I have a last question: it also seems that the mRNA produced is higher for the samples which are irradiated with respect to the not irradiated. I am not a biologist, but I was doing this statistical data analysis hoping to find this behavior, so that I can say that P. Furiosus, when exposed to gamma irradiation, produce more mRNA with respect to the samples not irradiated in order to repair better DNA . So this reasoning is nonsense? $\endgroup$
    – Manuela
    Sep 8 '20 at 19:16
  • $\begingroup$ @Manuela I don't think you can say much of anything without more information. You may be able to show that, on a cell by cell basis, irradiated cells seem to produce more total RNA than non-irradiated cells, but you can't say anything about why they're doing it. I strongly suggest talking to a biologist familiar with the details of your project. The vast majority of my work has been with mammalian systems, and for all I know there could be different DNA repair mechanisms in Archaea that I'm not familiar with. $\endgroup$
    – MattDMo
    Sep 8 '20 at 20:29
  • $\begingroup$ All right, thank you so much @MattDMo $\endgroup$
    – Manuela
    Sep 8 '20 at 20:31

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