It functioned even when inserted into human kidney cells, the researchers showed.
It was human kidney cells modified with fragments of the Ebola virus, not Ebola cells.
If a mutation prevents cilia from bending, kidney cells needlessly divide, and cysts form.
The researchers, from the University of Heidelberg in Germany and other European institutions, observed what they called tunneling nanotubes among embryonic human kidney cells and normal rat kidney cells.
When introduced into human embryonic kidney cells, the opsin made the cells respond to flashes of blue light.
The flask contained a culture of monkey kidney cells, known as Vero cells, which are fertile ground for certain viruses.
Nascent kidney cells were taken from the fetuses and placed on a two-inch-long, spongelike scaffolding.
They said they had inserted genes derived from two species of spiders into kidney cells from baby hamsters and udder cells from cows.
When they introduced this genetic construct into human embryonic kidney cells growing in Petri dishes, the cells synthesized the 'Magneto' protein and inserted it into their membrane.
There was every likelihood that it would be impossible in brain cells, which are far more complex and fragile than the kidney cells that the German team used.
His team took a different approach, choosing to re-engineer human kidney cells, known as HEK cells, to perform the function normally carried out by the pancreas.
