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Go to http://www.squarespace.com/microcosmos to get a free trial and 10% off your first purchase of a website or domain.
For James, our master of microscopes, the immense breadth has made ciliates a bit of an obsession. Whether he’s hunting down a rare species, or documenting the behavior of something more familiar, there’s always something spectacular in this group.
Follow Journey to the Microcosmos:
Twitter: https://twitter.com/journeytomicro
Facebook: https://www.facebook.com/JourneyToMicro
Shop The Microcosmos:
https://www.microcosmos.store
Support the Microcosmos:
http://www.patreon.com/journeytomicro
More from Jam’s Germs:
Instagram: https://www.instagram.com/jam_and_germs
YouTube: https://www.youtube.com/channel/UCn4UedbiTeN96izf-CxEPbg
Hosted by Hank Green:
Twitter: https://twitter.com/hankgreen
YouTube: https://www.youtube.com/vlogbrothers
Music by Andrew Huang:
https://www.youtube.com/andrewhuang
Journey to the Microcosmos is a Complexly production.
Find out more at https://www.complexly.com
Stock video from:
https://www.gettyimages.com/detail/video/infusoria-oxytricha-haematoplasma-under-a-microscope-stock-footage/1062456118
SOURCES:
https://www.nature.com/articles/srep24874
https://www.sciencedirect.com/science/article/abs/pii/S0932473922000293
https://ucmp.berkeley.edu/history/leeuwenhoek.html
https://linkinghub.elsevier.com/retrieve/pii/S007021530800803X
https://ciliajournal.biomedcentral.com/articles/10.1186/2046-2530-1-1
https://www.britannica.com/science/cilium
https://www.microscopyu.com/gallery-images/euplotes-protozoan-videos
https://pubmed.ncbi.nlm.nih.gov/19147002/
https://www.sciencedirect.com/science/article/pii/S0923250810002159
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5204320/
https://doi.org/10.1093/molbev/msx146
https://onlinelibrary.wiley.com/doi/10.1111/jeu.12926
https://ucmp.berkeley.edu/protista/ciliata/ciliatalh.html
https://pnas.org/doi/10.1073/pnas.2221818120
For James, our master of microscopes, the immense breadth has made ciliates a bit of an obsession. Whether he’s hunting down a rare species, or documenting the behavior of something more familiar, there’s always something spectacular in this group.
Follow Journey to the Microcosmos:
Twitter: https://twitter.com/journeytomicro
Facebook: https://www.facebook.com/JourneyToMicro
Shop The Microcosmos:
https://www.microcosmos.store
Support the Microcosmos:
http://www.patreon.com/journeytomicro
More from Jam’s Germs:
Instagram: https://www.instagram.com/jam_and_germs
YouTube: https://www.youtube.com/channel/UCn4UedbiTeN96izf-CxEPbg
Hosted by Hank Green:
Twitter: https://twitter.com/hankgreen
YouTube: https://www.youtube.com/vlogbrothers
Music by Andrew Huang:
https://www.youtube.com/andrewhuang
Journey to the Microcosmos is a Complexly production.
Find out more at https://www.complexly.com
Stock video from:
https://www.gettyimages.com/detail/video/infusoria-oxytricha-haematoplasma-under-a-microscope-stock-footage/1062456118
SOURCES:
https://www.nature.com/articles/srep24874
https://www.sciencedirect.com/science/article/abs/pii/S0932473922000293
https://ucmp.berkeley.edu/history/leeuwenhoek.html
https://linkinghub.elsevier.com/retrieve/pii/S007021530800803X
https://ciliajournal.biomedcentral.com/articles/10.1186/2046-2530-1-1
https://www.britannica.com/science/cilium
https://www.microscopyu.com/gallery-images/euplotes-protozoan-videos
https://pubmed.ncbi.nlm.nih.gov/19147002/
https://www.sciencedirect.com/science/article/pii/S0923250810002159
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5204320/
https://doi.org/10.1093/molbev/msx146
https://onlinelibrary.wiley.com/doi/10.1111/jeu.12926
https://ucmp.berkeley.edu/protista/ciliata/ciliatalh.html
https://pnas.org/doi/10.1073/pnas.2221818120
This episode is sponsored by Squarespace.
Go to squarespace.com/microcosmos to get a free trial and 10% off your first purchase of a website or domain. Here’s a little microcosmos joke for you.
What has two types of nuclei and is covered in hair? This guy. Well, never said it was a good joke.
But that hair and those nuclei have been beguiling scientists for centuries, so today, we are going to explore how two features that are so common to so many organisms can remain so mysterious. The organism we opened this video with is called Stentor coeruleus, and it belongs to a broader class of single-celled eukaryotes who are part of the phylum Ciliophora. But we know them as ciliates.
This group of organisms is vast and incredibly diverse. There are giants, like stentors, that can sometimes even be seen with the naked eye. There are armed ciliates, like this suctorian with tentacled arms protruding from their bodies to capture food.
And other ciliates, like these paramecium bursaria, fill up their body with endosymbiotic algae that exchange nutrients for protection. For James, our master of microscopes, the immense breadth has made ciliates a bit of an obsession. Whether he’s hunting down a rare species, or documenting the behavior of something more familiar, there’s always something spectacular in this group.
Everything ultimately revolves around ciliates. And that puts him in good company. One of the original masters of microscopes was Antonie van Leeuwenhoek, a Dutch tradesman who used his simple microscopes to examine everything from rainwater to his own waste.
Leeuwenhoek’s writings contained some of the earliest descriptions of ciliates, like this bell-shaped Vorticella. In 1675, Leeuwenhoek noted something interesting in one of his samples, which he called: “incredibly thin little feet.” Of course, the thin little feet he was writing of, were not actual feet. They were hairs, or more specifically, cilia.
Cilia are, of course, one of the main defining features of ciliates, though they are not unique to this group of organisms. In our own bodies, cilia are found on a number of cells, like sensory hair cells. Leeuwenhoek’s observation marks what is perhaps one of the first descriptions of a cell organelle.
They are made from tiny tube structures called microtubules, which are arranged to form a central core that is then surrounded by a ring of more microtubules. The whole thing is encased in a membrane that is attached to the cell’s membrane. And in ciliates, the hairy structure that forms can be quite distinctive and, of course, practical.
You can see them whirring here along the side of this amphileptus. The coordinated movements of the cilia can steer the organism through the microcosmos. In Euplotes and other ciliates, cilia can bundle together to form structures called cirri, which they can also put to work as they swim around.
And cirri and cilia alike can also help ciliates with eating. From one side, this condylostoma looks like an eel on the hunt for food, with cilia whirling around its oral apparatus to help it gather food. In some ciliates, those hairs act like a trap of sorts, helping to both bring in food and filter it through to the organism.
So you might wonder…how did ciliates get to be cilia-y in the first place? Who was the first microbial genius that invented these hairy structures? Well, we do not know.
Bacteria do have their own hair-like structures, but they are distinct from the cilia found on eukaryotes. They evolved separately. But somewhere in the past was an organism known as the Last Eukaryotic Common Ancestor.
This is the eukaryote at the root of all the eukaryotes we know today, including ourselves. We do not know the identity of this organism, but as our ability to study modern day organisms has expanded with new tools to understand them at the genetic level, there’s been a mishmash of features that we can trace back to this ancestor. And one of those features is, yes, cilia.
The Last Eukaryotic Common Ancestor likely had them. Which means that their origin traces back to something even older and more mysterious, something we still do not have the means to identify. What makes this even more interesting is that today, if we look across all the descendants of this mysterious ancestor, we can find plenty of organisms that do not have cilia, like amoeba.
Which means that as useful as cilia are, they have also been disposable to certain lineages. And that is fascinating in its own way because it reminds us that evolution is messy, and it doesn’t necessarily proceed in a straightforward path. A certain feature can spawn a number of advantages for an organism, that in turn forms an incredible array of species that contain that feature.
And then, by some mysterious evolutionary means, that feature can become unnecessary for some species, forming its own divergent corner of diversity through loss. But when it comes to messy evolution, ciliates have even more to offer. Like the fact that for some strange reason, many ciliates have two nuclei.
One is called the macronucleus, and the other is called the micronucleus. As you might have gathered from the names, the macronucleus is big, the micronucleu, small. But their differences, it turns out, go a lot deeper than that.
Some of the early descriptions of these two different types of nuclei actually came from descriptions of ciliates going through conjugation, which is the ciliate approach to sexual reproduction. And over time, scientists have found more and more difference between the macronucleus and the micronucleus going far beyond their size. The macronucleus contains the genes that get expressed in the organism, encoding the proteins that allow it to survive.
But something weird happens when ciliates with a macronucleus reproduce: their macronucleus gets destroyed in the process, disintegrating before it can pass down its information. Which leaves us with a question: how do you get the new offspring? Well, that is the job of the micronucleus.
It holds the genes that are passed down to the offspring, along with extraneous bits of DNA that either don’t code for anything or aren’t expressed in the organism. As the new offspring forms, it constructs its new macronucleus from the micronucleus, using bits of the old macronucleus to figure out what those extraneous bits of DNA in the micronucleus are so they can get cleared out by enzymes called transposases. It’s all kind of complicated and kind of redundant, right?
Like, why go through this process of destroying one nucleus and recreating it from another nucleus that also has a whole bunch of unnecessary bits that need to be cut out? Well, of course, it’s hard to know. Most of the information we have about this process comes from three ciliate species: paramecium, tetrahymena, and oxytricha.
Researchers have also been expanding to look at blepharisma, which is more distantly related to those three. That gives them a little bit more insight into what the ancestral ciliates might have looked like, but still leaves us far from being able to understand the point of this system. In 2023, two researchers presented their own hypothesis for how this system may have evolved in a paper titled “How ciliates got their nuclei.” In their speculation, there was once a small ancestor with just one nucleus and a transposase.
Over time, perhaps that small, single-nucleus ancestor became larger. And as it became larger, it demanded more and more protein production to survive, leading to the creation of more than one nucleus. And then, perhaps, one of those nuclei became larger and capable of holding multiple copies of its DNA.
It’s now a nucleus that has all the means to provide the proteins the organism needs, and so the other smaller nucleus can go quiet. There are still transposase enzymes in these nuclei, but they’ll only be active in the larger nucleus. So the bits of DNA that those enzymes normally cut out will accumulate in the smaller, quiet nucleus.
And so the genetic sequence in that smaller nucleus also begins to look less and less like the ancestral DNA of the organism. But the trouble is that the larger nucleus is too large to divide during reproduction, so it keeps getting lost. Well, luckily there’s that other smaller nucleus, with all the components you need to reconstruct the larger one.
It might take a little bit more effort, but it works. Again though, this is just a hypothesis, it is one potential story that boils down a mysterious history into a series of steps that makes some sense, but that we do not know enough to know if they are true. To know more, scientists will have to continue studying ciliates and gathering more of their DNA.
And every observation fills in a little more of the puzzle of how ciliates came to be, which in turn tells us just a little bit more about how we came to be. And we’ll talk more about that in our next episode. But for now, we just want to leave you with our friends, the ciliates, who so generously tell us about themselves just by existing and swimming across our view under the microscope.
Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And thank you to Squarespace for sponsoring this episode. If you don’t know what Squarespace is, it’s a powerful all-in-one platform for creating your own website.
So whether you are finally ready to start that podcast idea of yours, or manage a growing brand, Squarespace makes it easy to create a beautiful website, engage with your audience, and sell stuff from products to content to time, all in one place, all on your terms. And if you want a place to organize and share beautiful video content you can do that on Squarespace too. You can even set the price for viewers to access your videos, whether that’s a one-time fee, or subscription, or members-only content.
And with flexible payment options, checkout for your customers will be seamless. Squarespace also offers a ton of analytics to monitor traffic and sales, giving you the data you need to grow your audience. So go to Squarespace.com to sign up for a free trial, and when you’re ready to launch, go to squarespace.com/microcosmos to save 10% off your first purchase of a website or domain.
The people on the screen right now. They are our Patreon patrons. They liked this show so much that that they wanted to pay for it, even though they didn't have to.
They wanted to do that so that we could keep making it, because they know that it's very hard to make weird, fun, niche microscopy videos on YouTube. If you liked this show, they're the people to thank. And I do like this show.
So thank you so much to all of them. If you want to also sign up, you can do that and also get some cool perks at Patreon.com/JourneytoMicro. If you want to see more from our Master of Microscopes, James Weiss, you can check out Jam and Germs on Instagram.
And if you want to see more from us, there's always a subscribe button somewhere nearby.
Go to squarespace.com/microcosmos to get a free trial and 10% off your first purchase of a website or domain. Here’s a little microcosmos joke for you.
What has two types of nuclei and is covered in hair? This guy. Well, never said it was a good joke.
But that hair and those nuclei have been beguiling scientists for centuries, so today, we are going to explore how two features that are so common to so many organisms can remain so mysterious. The organism we opened this video with is called Stentor coeruleus, and it belongs to a broader class of single-celled eukaryotes who are part of the phylum Ciliophora. But we know them as ciliates.
This group of organisms is vast and incredibly diverse. There are giants, like stentors, that can sometimes even be seen with the naked eye. There are armed ciliates, like this suctorian with tentacled arms protruding from their bodies to capture food.
And other ciliates, like these paramecium bursaria, fill up their body with endosymbiotic algae that exchange nutrients for protection. For James, our master of microscopes, the immense breadth has made ciliates a bit of an obsession. Whether he’s hunting down a rare species, or documenting the behavior of something more familiar, there’s always something spectacular in this group.
Everything ultimately revolves around ciliates. And that puts him in good company. One of the original masters of microscopes was Antonie van Leeuwenhoek, a Dutch tradesman who used his simple microscopes to examine everything from rainwater to his own waste.
Leeuwenhoek’s writings contained some of the earliest descriptions of ciliates, like this bell-shaped Vorticella. In 1675, Leeuwenhoek noted something interesting in one of his samples, which he called: “incredibly thin little feet.” Of course, the thin little feet he was writing of, were not actual feet. They were hairs, or more specifically, cilia.
Cilia are, of course, one of the main defining features of ciliates, though they are not unique to this group of organisms. In our own bodies, cilia are found on a number of cells, like sensory hair cells. Leeuwenhoek’s observation marks what is perhaps one of the first descriptions of a cell organelle.
They are made from tiny tube structures called microtubules, which are arranged to form a central core that is then surrounded by a ring of more microtubules. The whole thing is encased in a membrane that is attached to the cell’s membrane. And in ciliates, the hairy structure that forms can be quite distinctive and, of course, practical.
You can see them whirring here along the side of this amphileptus. The coordinated movements of the cilia can steer the organism through the microcosmos. In Euplotes and other ciliates, cilia can bundle together to form structures called cirri, which they can also put to work as they swim around.
And cirri and cilia alike can also help ciliates with eating. From one side, this condylostoma looks like an eel on the hunt for food, with cilia whirling around its oral apparatus to help it gather food. In some ciliates, those hairs act like a trap of sorts, helping to both bring in food and filter it through to the organism.
So you might wonder…how did ciliates get to be cilia-y in the first place? Who was the first microbial genius that invented these hairy structures? Well, we do not know.
Bacteria do have their own hair-like structures, but they are distinct from the cilia found on eukaryotes. They evolved separately. But somewhere in the past was an organism known as the Last Eukaryotic Common Ancestor.
This is the eukaryote at the root of all the eukaryotes we know today, including ourselves. We do not know the identity of this organism, but as our ability to study modern day organisms has expanded with new tools to understand them at the genetic level, there’s been a mishmash of features that we can trace back to this ancestor. And one of those features is, yes, cilia.
The Last Eukaryotic Common Ancestor likely had them. Which means that their origin traces back to something even older and more mysterious, something we still do not have the means to identify. What makes this even more interesting is that today, if we look across all the descendants of this mysterious ancestor, we can find plenty of organisms that do not have cilia, like amoeba.
Which means that as useful as cilia are, they have also been disposable to certain lineages. And that is fascinating in its own way because it reminds us that evolution is messy, and it doesn’t necessarily proceed in a straightforward path. A certain feature can spawn a number of advantages for an organism, that in turn forms an incredible array of species that contain that feature.
And then, by some mysterious evolutionary means, that feature can become unnecessary for some species, forming its own divergent corner of diversity through loss. But when it comes to messy evolution, ciliates have even more to offer. Like the fact that for some strange reason, many ciliates have two nuclei.
One is called the macronucleus, and the other is called the micronucleus. As you might have gathered from the names, the macronucleus is big, the micronucleu, small. But their differences, it turns out, go a lot deeper than that.
Some of the early descriptions of these two different types of nuclei actually came from descriptions of ciliates going through conjugation, which is the ciliate approach to sexual reproduction. And over time, scientists have found more and more difference between the macronucleus and the micronucleus going far beyond their size. The macronucleus contains the genes that get expressed in the organism, encoding the proteins that allow it to survive.
But something weird happens when ciliates with a macronucleus reproduce: their macronucleus gets destroyed in the process, disintegrating before it can pass down its information. Which leaves us with a question: how do you get the new offspring? Well, that is the job of the micronucleus.
It holds the genes that are passed down to the offspring, along with extraneous bits of DNA that either don’t code for anything or aren’t expressed in the organism. As the new offspring forms, it constructs its new macronucleus from the micronucleus, using bits of the old macronucleus to figure out what those extraneous bits of DNA in the micronucleus are so they can get cleared out by enzymes called transposases. It’s all kind of complicated and kind of redundant, right?
Like, why go through this process of destroying one nucleus and recreating it from another nucleus that also has a whole bunch of unnecessary bits that need to be cut out? Well, of course, it’s hard to know. Most of the information we have about this process comes from three ciliate species: paramecium, tetrahymena, and oxytricha.
Researchers have also been expanding to look at blepharisma, which is more distantly related to those three. That gives them a little bit more insight into what the ancestral ciliates might have looked like, but still leaves us far from being able to understand the point of this system. In 2023, two researchers presented their own hypothesis for how this system may have evolved in a paper titled “How ciliates got their nuclei.” In their speculation, there was once a small ancestor with just one nucleus and a transposase.
Over time, perhaps that small, single-nucleus ancestor became larger. And as it became larger, it demanded more and more protein production to survive, leading to the creation of more than one nucleus. And then, perhaps, one of those nuclei became larger and capable of holding multiple copies of its DNA.
It’s now a nucleus that has all the means to provide the proteins the organism needs, and so the other smaller nucleus can go quiet. There are still transposase enzymes in these nuclei, but they’ll only be active in the larger nucleus. So the bits of DNA that those enzymes normally cut out will accumulate in the smaller, quiet nucleus.
And so the genetic sequence in that smaller nucleus also begins to look less and less like the ancestral DNA of the organism. But the trouble is that the larger nucleus is too large to divide during reproduction, so it keeps getting lost. Well, luckily there’s that other smaller nucleus, with all the components you need to reconstruct the larger one.
It might take a little bit more effort, but it works. Again though, this is just a hypothesis, it is one potential story that boils down a mysterious history into a series of steps that makes some sense, but that we do not know enough to know if they are true. To know more, scientists will have to continue studying ciliates and gathering more of their DNA.
And every observation fills in a little more of the puzzle of how ciliates came to be, which in turn tells us just a little bit more about how we came to be. And we’ll talk more about that in our next episode. But for now, we just want to leave you with our friends, the ciliates, who so generously tell us about themselves just by existing and swimming across our view under the microscope.
Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And thank you to Squarespace for sponsoring this episode. If you don’t know what Squarespace is, it’s a powerful all-in-one platform for creating your own website.
So whether you are finally ready to start that podcast idea of yours, or manage a growing brand, Squarespace makes it easy to create a beautiful website, engage with your audience, and sell stuff from products to content to time, all in one place, all on your terms. And if you want a place to organize and share beautiful video content you can do that on Squarespace too. You can even set the price for viewers to access your videos, whether that’s a one-time fee, or subscription, or members-only content.
And with flexible payment options, checkout for your customers will be seamless. Squarespace also offers a ton of analytics to monitor traffic and sales, giving you the data you need to grow your audience. So go to Squarespace.com to sign up for a free trial, and when you’re ready to launch, go to squarespace.com/microcosmos to save 10% off your first purchase of a website or domain.
The people on the screen right now. They are our Patreon patrons. They liked this show so much that that they wanted to pay for it, even though they didn't have to.
They wanted to do that so that we could keep making it, because they know that it's very hard to make weird, fun, niche microscopy videos on YouTube. If you liked this show, they're the people to thank. And I do like this show.
So thank you so much to all of them. If you want to also sign up, you can do that and also get some cool perks at Patreon.com/JourneytoMicro. If you want to see more from our Master of Microscopes, James Weiss, you can check out Jam and Germs on Instagram.
And if you want to see more from us, there's always a subscribe button somewhere nearby.