In a lab in MIT, a flatworm is dying. It’s a planarian – a simple animal that is normally very difficult to kill. Planarians are masters of regeneration; whole animals can be reborn from small clumps of tissue. If you cut one in half, it will simply grow into two planarians. But this animal has been bombarded with high doses of radiation that have wiped out its ability to regenerate. Slowly, its cells are bursting apart. With no new ones to replace them, the planarian has a few weeks to live.
But Daniel Wagner and Irving Wang are about to save it, in a fashion. They transplant one special cell from a donor planarian into the terminal individual’s tail. The cell starts to divide. It produces skin, guts, nerves, muscle, eyes and a mouth.
As the planarian dies from the head backwards, the transplanted cells spread from the tail upwards. At its worst, the animal is a stunted mass with no discernible head. But two weeks after the transplant, it has completely regenerated. A new planarian has risen, phoenix-like, from the ashes. Its entire body is now genetically identical to the single transplanted cell. Read More
Conspiracy theories, TV thrillers and airport novels are full of the idea that the world is secretly run by a hidden society. We have come up with many names for this shadowy cabal of puppet-masters – the Illuminati, the Freemasons, and more. But a better name would be ‘parasites’.
Every animal and plant is afflicted by parasites. The vast majority are simple, degenerate creatures, small in size and limited in intelligence. They affect our health and development, and even our behaviour and culture. And by pulling the strings of key species, parasites can change the face of entire habitats.In a typical school textbook, an ecosystem consists of plants that feed plant-eaters, who in turn, line the bowels of predators. But parasites influence all of these levels, and as such, they can change the structures of entire communities.
The idea that nature is secretly manipulated by these tiny, brainless creatures is unsettling but manipulate us, they do. And by changing the behaviour of their hosts, parasites can change the face of entire habitats. Chelsea Wood and colleagues from Dartmouth College have found compelling evidence for this, by showing that a tiny flatworm can alter the structure of a tidal habitat by infecting small marine snails.