It may be the closest scientists have yet come to creating Frankenstein’s monster. Living pieces of dozens of individual animals known as comb jellies have been fused together to create an array of new forms that, in some cases, survived for more than a week.
These chimeric animals are more than just physically connected bits of different individuals, says at the University of Florida. Their nervous systems also fuse together, creating entities that heand his colleague Tigran Norekian, also at the University of Florida, call “neurobots”. “We were able to directly prove that the neural system fused,” he says.
This kind of experiment offers “unprecedented” opportunities for synthetic biology, says Moroz. The researchers’ ultimate aim is to improve our understanding of biology to the point where we will be able to grow tissues and organs for treating various diseases.
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“If you are a good engineer, you can eventually make a bridge or airplane,” says Moroz. “In biology and medicine, we’re far, far away. Biology is much more complicated.”
His work was inspired by a recent study by who is now at the National Institute for Basic Biology in Japan, and his colleagues. When Jokura was studying a species of comb jelly, or ctenophore, called Mnemiopsis leidyi, he noticed a strange animal that seemed to consist of two fused individuals.
Further experiments showed that when pairs of injured individuals were put together, they fused with each other 9 times out of 10.
Moroz and Tigran Norekian, also at the University of Florida, have now gone much further, fusing various different parts of individual ctenophores together. For instance, they took the part of a comb jelly that contains its primitive brain from one individual and used it to replace that part on another individual – the ctenophore equivalent of a head transplant. “Virtually all possible combinations were able to produce [moving] animals,” says Moroz.
By using a stain that binds to a component in neurons, the pair confirmed that nerve cells grew connections across the fusion scar and connected the neural networks of different individuals.
The researchers have also combined parts from more than two individuals. Moroz says they have now fused “many dozen” into single entities.
Moroz and Norekian have also shown that this fusion works in at least two other species of ctenophores, Bolinopsis microptera and Pleurobrachia bachei. They are now testing whether a part of one species can be fused with a part from another species. “When you called, I was doing this experiment,” says Moroz, who wouldn’t give anything anyway about the results so far.
Parts of other kinds of animals can’t usually be fused together because their immune system will attack “non-self” cells – this is why organ transplants usually require immune suppression. But ctenophores branched off from other animals very early on, and it appears their immune systems never evolved the ability to distinguish self from non-self.
“I’m thrilled to hear that our work has inspired further research,” says Jokura. “I’m particularly excited to learn about Leonid Moroz’s efforts to push the boundaries of this phenomenon by exploring cross-species fusion and the potential for fusing multiple individuals.”
A lot of biological research is subtractive, says Jokura: genes are disabled or removed to see what happens. With this kind of fusion, it is possible to do “additive” research, he says, to see how things work when put together.
“Fusion experiments could provide an entirely new lens through which to study physiological phenomena and may indeed lead to innovative approaches in synthetic biology,” says Jokura.
bioRxiv
