DNA analysis of oldest living land animal reveal patterns on genes that appear to protect functioning of mitochondria

The ancient quest to extend human lifespan has received a boost after scientists analysed the genetic code of the world’s oldest living land animal, a giant tortoise called Jonathan.

The tortoise, which lives in the grounds of Plantation House, the official residence of the governor of Saint Helena in the South Atlantic, is believed to be 194 years old, making him a contemporary of Queen Victoria and Charles Darwin.

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© Photograph: St Helena Government, Communications Hub

© Photograph: St Helena Government, Communications Hub

© Photograph: St Helena Government, Communications Hub

Rosalind Franklin knew exactly what she had.

James Watson's claim that he'd recognised what Franklin had failed to see in her famous photograph of DNA's helical structure was taken at face value in part because she'd left no notes about the image. Researchers have now shown that it's because it was a second photo, taken to correct the centring and contrast of a first—which Franklin had made extensive notes about, and had used "to calculate, for the first time, the length of each turn in the spiral—34 angstroms—and the number of bases 'per turn of helix (if there is a helix).'"

Over decades of research, scientists have built up a partial picture of what specialized cells within the brain and spinal cord do. By studying how the brain develops, they could identify genes that were active in different populations of neurons and where in the brain those neurons resided. In some cases, these genes could then be used to genetically delete the neurons, allowing us to get some indication of what they might be doing, building on the information we've obtained from studies of brains with damaged regions.

But this approach has its limits. The brain is flexible enough to potentially adapt to the loss of some cells, and their loss early in development may alter the development of any neurons they would have normally formed connections with. It would be far more informative to activate and shut down the neurons in an otherwise intact brain.

Today's Nobel Prize in Physiology or Medicine rewards three people—Karl Deisseroth, Peter Hegemann and Georg Nagel—who developed our ability to do precisely that. Starting from studies of single-celled algae that are attracted to light, these and many other researchers built an entire field of study that we now call optogenetics: using light to alter the behavior of nerve cells marked by the activity of individual genes.

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