When we first looked up to the stars, we couldn’t help but imagine what might live there, yet,
so far, we have found nothing.
When we first looked down into a microscope though, well, we found more than we could
ever have guessed.
Let’s pretend that you and I are among the earliest viewers of microbes, peering through
a tiny piece of crafted glass set into a brass plate.
And, through that lens, we see a world that is both entirely new, and unknowably ancient.
And as we look, still in the earliest days of charting this landscape, of cataloging
strange organisms that defy or blur the classifications of plant or animal.
We see, among those myriad, mysterious creatures—those bejeweled diatoms and charming rotifers that
make up our initial glimpses of the microcosmos—an ensemble of blue or green trumpets: large
compared to many of the other organisms we see, their elongated bodies adorned in rows
and rows of little hairs.
It’s that horn shape that will end up identifying them not just by sight, but by name: Stentor,
for the herald of the Greek troops during the Trojan War whose voice was said to carry
with the strength of fifty men.
Of course, our tools and understanding of microbes have come a long way since those
first microscopic investigations, making it possible for us to share this footage of our
own observations with you.
Recently, outside Warsaw, James found a small pond in the middle of a forest that is filled
with microbes.
That pond has given us more Stentors to collect and film, which means it’s also provided
us with an excuse to check in again on our favorite under-appreciated organisms of the microcosmos.
After all, Stentor’s voice carried through millennia, but the legend of the microbial
Stentor seems more muted across the centuries compared with some of the more studied ciliates.
But modern scientific tools are giving us a new appreciation for Stentors.
But before we get there, we should note that it’s not like Stentors have never held any
fascination for scientists.
As we talked about in our last Stentor-focused episode, these single-celled organisms have
a complex body and an incredible capacity for regeneration.
That regeneration process mirrors some of the steps that drive the development of animal
embryos, making Stentors a compelling object of study all the way through the mid-20th century.
But research is as much about the practicalities as it is about exciting questions and implications.
And for many scientists, Stentors were simply not the right choice for their experiments.
They were difficult to grow, and, in part because of their tremendous size, they couldn’t
be used in the same experimental set-ups that other organisms were more amenable to.
And so other ciliates that were easier to work with, like paramecium, went on to become
more popular model protozoa, teaching us through the lens of their own single-celled eukaryotic bodies.
But Stentors weren’t forgotten, they were just awaiting the right tools.
We here work with the basics: forest ponds, a microscope, and yes hundreds of hours spent
checking on our Stentors.
And we still manage to find them in incredible situations.
This little ciliate pulls and pulls at the stentor’s membrane until it just…erupts.
You can see the bead-like nuclei pouring out of the Stentor along with the food vacuoles
and the rest of the cytoplasm, the inside of its body now scattered around it.
And yet…for all the damage that is inflicted on this Stentor, it survives.
It’s one thing to know that Stentors are capable of this kind of regeneration, another
thing altogether to witness its survival in real time on our slides.
This regenerative capacity, their shape, their color, their size, the fact that they are
single-celled organisms, all of those factors make it seem like we must not have much in
common with Stentors.
And if we were just reliant on what we could see, we might still believe that.
But with the ongoing development of new genetic tools, it’s the thing we’ve discovered
that we share in common with Stentors, and that actually renders them distinct from much
of their brethren, that has given our trumpet friends a new role in the study of the microscopic world.
When it comes to genetics, we often think of DNA as a universal code...this is the simple
story that we’re taught in biology class.
Three base-pair sequences of DNA code for amino acids to be added onto a protein over
and over until a gene ending code is reached and the protein is complete.
And those codes that decide what amino acid is added onto the protein, well, we’re taught
that that is a universal thing.
It is not.
There is what we call the standard code, the one that we, and all multicellular organisms use.
And then there are others where letters change, and punctuation becomes words, and most of
these are bacterial or mitochondrial code.
But especially among eukaryotes, ciliates are noted genetic eccentrics due to their
tendency to take some of the sequences that, in our code, signal the end of a gene, and
interpret them as coding for yet more amino acids to stack onto the protein.
Different ciliate lineages have evolved their own versions of this altered interpretation,
but there are only a few ciliates that have been thought to follow the standard genetic
code that the rest of us do and Stentors are one of them.
And with recent genetic techniques probing the sequences of Stentor coeruleus, that strange
conformity has now been confirmed.
Usually, when we bring up genetic studies of microbes on this channel, they raise questions
about the details of classification schemes.
In the case of Stentors though, they raise a deeper question: why do they resemble us
in this way, and why don’t the vast majority of other ciliates?
If Stentor coeruleus follows the standard genetic code, does that mean the original
ciliate also did?
And if so, then does that mean the nonstandard genetic codes exhibited by so many ciliates
now are not some property inherent to the phylum, but a product of an evolutionary path
that started after the Stentor family began to branch away, a very very long time ago?
Evolution is weird and messy.
It is a knot that sometimes seems to become more tangled the more we try to unravel it.
And Stentors, well, they’re confirmation that no matter how simple something may seem—whether
it’s their own surprisingly complex single-celled bodies or the supposed universality of the
genetic code—it only takes a few “what’s”, “why’s,” and “how’s” to find yourself
enmeshed in a web of questions that is not unlike the marvelous mysteries first uncovered
by the original microbe hunters hundreds of years ago.
Their discoveries were world changing, but so are ours.
We live in a time of great knowing, of great uncovering, but that has also helped us realize
how many mysteries we have yet to solve.
Thank you for coming on this journey with us as we explore the unseen world that surrounds us.
If you would like to get a pin celebrating the majesty of this peculiar organism, we
have Stentor coeruleus pins available now.
There’s a link in the description.
And also thank you so much to all of our patrons on Patreon who allow us to continue these
explorations and keep our eyes out for more bizarre happenings in our microscopes.
Without people like this, the work we’re doing here on Journey to the Microcosmos would
not be possible.
So if you’re able to potentially join them, that would be amazing.
And thank you to all of the people on this list.
If you want to see more from our Master of Microscopes, James, you can check out Jam
& Germ’s on Instagram.
And if you want to see more from us, here at Journey to the Microcosmos, you can find
us at youtube.com/microcosmos.