Tadpoles Survive Without Breathing After Scientists Fill Their Brains With Algae

'Are you wearing...' – 'Algae? Yeah, I am.' Image credit: Credit S Özugur et al, 2021 iScience

An illuminating study that turned tadpoles bright green recently found out that if you inject algae into their brains, tadpoles can survive even when their blood stops bringing oxygen to the brain. The remarkable feat was facilitated by photosynthesis, as green algae and cyanobacteria that were supplied to the brain’s blood vessels became a robust resource of oxygen in the brain. This meant that even without breathing, the tadpole’s brain function remained.

An animal borrowing the respiratory trick of plants isn’t unheard of, with the charismatic “Shaun the Sheep” sea slug (Costasiella kuroshimae) having already made use of chloroplasts in its tissues as a means of getting energy. This is known as kleptoplasty, a process through which chloroplasts are “stolen” by a host from its food and incorporated into their own cells. The same process may be what allows the decapitated heads of self-decapitating sea slugs to survive while they grow back a new body (in case you weren't aware, all sea slugs are crazy).

This new research, published in the journal iScience, looked to see if it could find a way to hijack photosynthesis as a means of oxygenating the neurons in the brain of a tadpole so its neuronal activity could survive even in hypoxic conditions. They introduced the algae using what’s known as a “transcardial injection,” essentially squirting it into the vessels that supply the brain, as seen in the video below.

The injected algae then set up camp in the blood vessels of the brains of Xenopus laevis tadpoles, who were exposed to hypoxic conditions. As their blood oxygen depleted, the neuronal activity in their brains ground to a halt. However, when the researchers shone a light on the tadpoles, triggering photosynthesis, the algae that had colonized their brains was able to produce enough oxygen to kickstart brain function.

While the idea of zombie tadpoles with algae brains surviving without breathing is, undeniably, an incredibly cool one, it has more pragmatic applications, too.

“This method would be immediately useful for in vitro studies on brain slices or organoids or any isolated tissue from animals where oxygen supply is difficult but necessary to have the tissue surviving for experimentation,” said study author Hans Straka to IFLScience.  

“On the very long run one could envision that algae could assist in providing additional oxygen in case of difficulties in respiration; application ways need to be improved however and immune reactions clarified and toxic reaction ruled out.“

Following an accident or heart attack, hypoxia can occur in the human body as the blood starts failing to provide the brain with sufficient oxygen. This means that the length of an ambulance journey can be the difference between life, death, or a permanent loss of neural function as the brain starts to die. If a therapy along the lines of injecting some brain algae and shining a light could bridge the gap from the scene of the accident to the operating theater, this damage could be prevented.

“But what about the light?!” I hear you cry, “How will you activate the brain greens?!”

Oh, ye of little faith.

“Light penetration is less a problem than thought,” explained Straka, “because photosynthesis already starts at very low light levels.”

Now there’s some (plant-based) food for thought.

[H/T: The Scientist]


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