A CELL IS MUCH MORE THAN WE THINK IT IS
Health
For long, biologists have viewed themselves as fully acquainted with the essence of a cell: its formation, composition and capabilities. However, a recent finding seems to brazenly refute their claim, gauging their endeavours so far much as if setting about to review a book by merely poring over its abstract!
We have always known cells to be the basic building blocks of life. They are observed to replicate in order to reproduce, determine the genetic makeup of the creature and, of course, take in nutrients from food and convert them into energy — all accounting for the capacity of a human. Nonetheless, the existence of a prime trait of humans — the ability to remember and take decisions — was putatively enigmatic, as its very ingredients (cells) were considered to be devoid of it — until only recently. So guess what? The explanation for it too leapt right from the typical place — the cells.
Yes! A living cell runs the gamut from thinking prudently on its own and forming pragmatic decisions to preserving events as memory, substantially as though having a brain of its own. Although a new finding, the story of its discovery surprisingly dates back to over a century ago. In 1906, a zoologist named Herbert S.Jennings decided to play about with a microbe called Stentor: a trumpet-shaped cilia-bound single cell, large enough to be perceptible to the naked eye and enterprising enough to dine on rotifers — a proper multicellular animal and a behemoth in comparison. She noted that when blazed with streaks of carmine powder (a natural dye) delicately aimed towards its mouth, it would nullify the onslaught by first bending away, then reversing the whacking of its hair (cilia) to repulse the powder, then contracting before finally retreating. Further, just as intriguing as this is, if not more so, it was observed that the reaction steps shuffled with different stimuli (powders), and sometimes some were even eliminated. In essence, a stentor could employ one approach to ride out a stimulus, and if in vain, it would resort to another. This demonstrates that after applying the first one and encountering its unwelcome upshot, it must have remembered this experience— at least for a radically short time — to take up the decision for the second one and hence implement it.
However, the path of nearly every, if not literally every, such novel discovery to scholarly credence is not linear, and this one is no anomaly. In 1967, a group of scientists, from some other school of animal behavior, sought to replicate Jennings’ experiment. To their astonishment, their attempt failed to yield the same results, by dint of which Jennings’ findings were utterly stripped of any further scientific concern for a series of decades to come.
Fast forward to the current 21st century, and the situation turns over a new leaf. About 10 years ago, Jeremy Gunarwadena, an associate professor of systems biology at Harvard Medical School, stumbled upon the experiment and decided to revisit it. Subsequently, it transpired that the 1967 team had tripped up in their attempt to imitate the original experiment: they had used a different species of Stentor than the one Jennings had chosen, with the two being as distinct as one (Jennings’) preferring to hover poolside, while the other (1967 team’s) having a strong bias towards swimming in the midst! Honestly, they couldn’t be more fallible.
Now quite conceivably, Jeremy could not wait to behold what would further unfold by facsimiling the experiment once again, not to mention by drawing on an extended pool of knowledge. Consequently, after shaping up a team, they were able to hunt the correct species of Stentor in a golf course pond and construct a gadget to generate stimuli. Interestingly, this time Stentor behaved consistently with Jennings’ descriptions not when confronted with carmine powder but, rather, when assaulted with a fusillade of 21st-century plastic microbeads. This indicates that Stentor might, in fact, be able to inherently decide its response to a specific stimulus in accord with its aptness.
And the story does not end here. Stentor has also signaled us our cue to swallow that they have personalities. In yet another experiment with them in 2019, a bunch of Stentors was shelled by a string of beads, in response to which there were stark variations of behavior amongst them. One group emanated optimism (nonchalance towards the stimulus) by constantly alternating between contraction and relaxation or by bending, then contracting before finally relaxing. Whereas, another group exhibited pessimism (dread towards the stimulus) by contracting a few times and never relaxing or by contracting and then retreating once and for all. There were also some (say, fatalists) who only retaliated through one or two preferred behaviours, never trying others that they were just as qualified to execute.
Conclusively, it merits mention that such comportment of a single living cell as encompassing its ability to remember, make decisions, and personality traits, manifested in these groundbreaking experiments, is not sustained by any known cellular mechanism. Some scientists have conjectured, ascribing the behaviour to its spirit, or DNA as we call it, whilst others have tied it to its other structures and mechanisms, like extracellular matrix, bioelectricity or even simple protein clumping. Nevertheless, the issue still flies in the face of our preconceived notions about a cell, and it, hence, continues to pose a puzzle that has to be pieced together sooner or later to untangle the nature of our very own existence.
Credits:
- Fig.1 Photo by Hal Gatewood on Unsplash
- Fig.2 Photo by Flickr, unmodified, https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode
