The ‘powerhouse of the cell' is as hot as Death Valley in August
Mitochondria, the cell organ that supplies almost all human cells with energy, may be as hot as California’s Death Valley in the midst of summer – at around 50 degrees Celsius.
Despite the human body staying at a pretty stable 37.5 degrees Celsius, researchers found that on average, mitochondria were always about 10 degrees hotter than the rest of the cell.
Scientists from France, Korea, Germany, Finland and Lebanon collaborated on the study, growing human skin and embryonic kidney cells in a lab close to body temperature.
Led by Dominique Chretien of the French National Institute of Health and Medical Research, they painted mitochondria (which are about the size of E. coli bacteria) with a temperature-sensitive dye that becomes slightly less fluorescent as things get warmer.
From that, they were able to work out how hot the mitochondria were getting, and they were always between seven and 12 degrees Celsius warmer than the rest of the cell.
Their finding is controversial though, with another article in the same journal from a professor of evolutionary biochemistry at UCL calling the claim “radical”, writing: “I doubt that the 10 degree Celcius temperature difference should be taken literally.”
But their work is backed up by other authors – last year Japanese scientists found that the mitochondria in human cancer cells were 9 degrees warmer than the rest of the cell.
But why are mitochondria so warm?
The so-called “powerhouse of the cell” releases energy by converting oxygen and glucose into carbon dioxide and water, creating a chemical called ATP, which is the energy currency the rest of the cell runs on.
Because this process isn’t completely efficient, the authors of this paper say “a significant fraction of the released energy is dissipated as heat”.
They also found that the enzymes that speed up this ATP-creating reaction worked best at temperatures around the 50 mark – more evidence that mitochondria really are that hot.
The study was published in the journal PLOS Biology and can be read in its entirety here.