How long can you hold your breath before your brain starts to give out, forcing your lungs to take in a giant gasp of air?
If you're a normal human being, not very long. At least, not without developing some kind of brain damage, or dying.
Most living things on this planet require oxygen in order to live. And among those living things, animals need to actually breathe it in to stay alive. Plants, on the other hand, rely on the power of light, or photosynthesis to produce their oxygen.
Two worlds collide.
In a new study published in iScience on October 13, researchers have found that it is indeed possible for non-plant living things to get their vital oxygen supply without the need to breathe it in – bringing both worlds together in a weird, but wonderful fusion of conventional brain function and the oxygen-harnessing powers of photosynthesis.
Through various experiments on tadpoles that had their heads removed, scientists injected either green algae or cyanobacteria into their hearts. Traditionally, green algae and cyanobacteria make oxygen from carbon dioxide when exposed to light.
Employing that understanding on the now-headless, algae/cyanobacteria-infused tadpoles, scientists sought to figure out if it was actually still possible for the creatures to get oxygen by exposing them to light.
Amazingly, the team found an increase in oxygen concentration in the animals' ventricles. Conversely, in untreated tadpoles, there was no increase in oxygen concentration.
When researchers got rid of all the oxygen in the water that the animals were swimming around in, all neuronal activity ceased completely, including that of the treated tadpoles. But by shining light on the animals that got cyanobacteria or green algae injected into their hearts, the scientists were able to restart brain activity. And of course, when they turned off the light, everything ceased again.
“The authors employ an elegant and easily reproducible experimental approach to examine the effects of activation of photosynthetic organisms as a way to directly increase oxygen levels in the brain,” remarked Diana Martinez, a neuroscientist at Rowan University in New Jersey not involved with the study.
More than anything, Martinez sees the work as a proof of principle.
Still early days.
While one might make the logical connection between the treated tadpoles and modern human medicine – specifically in treating brain injuries – Martinez is quick to point out that it isn't as easy as it sounds, due to the biological and neurological complexities of other animals.
“The first issue is that Xenopus laevis tadpoles are transparent and light can easily pass through the skin to activate photosynthetic machinery to produce oxygen," she says. "Use in more complex animals would . . . be difficult, as light does not easily traverse the skin and may not reach the vasculature to activate the photosynthetic organisms."
Taking the photosynthesis strategy to the hospital is a reality that is still "very far away", according to Hans Straka, neuroscientist at the Ludwig Maximilian University of Munich (LMU) and co-author of the study.
For now, the team plans to put all their focus solely on the effects of introducing such photosynthesizing organisms into other living things, in addition to finding out whether the sugars produced by the microbes can actually be used by the tadpoles' brains.
“Over the last decade, there are quite a few projects where people have been trying to set up artificial symbiotic associations with algae, in order to augment in some way or manipulate vertebrate physiology, which is really radical,” says Ryan Kerney, a biologist at Gettysburg College in Pennsylvania.
Kerney also expresses a little hesitance with the study's technique, saying experiments that introduce microbes into tissues or cells – and then change their functions – are unregulated and under-scrutinized compared to similar techniques like gene modification.
“But the potential implications are also just fascinating to speculate about: Can we get away from breathing as a way to keep our brains going?”
Only time will tell, perhaps.
Click here to check out the full study.
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Cover image sourced from AquaTerra-Life / YouTube and pressfoto / Freepik.
