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Thanks to Brilliant for supporting this episode of Journey to the Microcosmos.

Go to Brilliant.org/microcosmos to get 20% off an annual premium subscription! We’re nearing the end of our fourth season of Journey to the Microcosmos, and over that time, we’ve been able to see microbes through all kinds of lenses—literally—thanks to James, our master of microscopes.

For the rest of us on the Microcosmos team, it’s been really cool to not only see the footage that James has recorded, but also see the journey that he has been on with the microscopes themselves. Now, we’ve been able to make this journey because of all of you and the support you have shown to this channel by watching and commenting and sharing with others, or even and especially by supporting us on Patreon. We’ve all been on this journey together, so let’s look back on where it’s taken us, and also get a peek at where we’re going in the future.

In the first season, James started out with two microscopes. One was a microscope that he assembled himself from different parts for under $200. The other microscope was a Motic BA310 that he received from a microscope company shortly after we started this channel.

And these microscopes give us so much beautiful footage, thanks in part to the different techniques that James used with them, whether that was bright-field or phase contrast or darkfield, or some other technique to manipulate the light shining on the microcosmos. But these microscopes also had their limits, so we were really excited to see what would happen when James bought a new microscope before the start of our third season: the Zeiss Axioscope 5. This new microscope came with higher quality objectives (which are the lenses on the bottom of the microscope), as well as prisms that made it possible for us to look at microbes with differential interference contrast microscopy, a technique that sharpened their features and made them seem more three-dimensional on our screen.

We have videos exploring these different techniques and microscopes, so if you want to learn more about them, we recommend checking those out because light is much weirder than it seems. But we wanted to do a quick summary for reasons that are probably very clear from the title of this video: we have upgraded our microscope! The Zeiss Axioscope 5 was a very exciting change, but it was also an expensive one.

So when James bought it, he was only able to get two objectives: a 20x objective and a 63x objective. Adding that to the 10x magnification the eyepiece gives, let us magnify our samples by 200x and 630x respectively, which is not bad. But a standard microscope usually comes with 5-6 objectives for a reason: the microcosmos is full of things both small and large to observe and there isn’t a one-size-fits-all objective that you can use to observe everything.

So one of James’ priorities was expanding his set of objectives so that he could have the flexibility to see the microcosmos at more scales. And thanks to his recent upgrade, he’s now gone from a set of 2 to a set of six that range from 5x to 100x and that gives us a magnification range from 50x to 1000x. Since I have gotten my own prototype of the microcosmos microscope that we are manufacturing thanks to backers of our kickstarter, I’ve been amazed at how important it is to have this variety of options, and how much time I spend on the lower magnifications and well as going deeper .

So without further ado, let’s introduce these different objectives by looking at a ciliate called Tetrahymena that’s taken up residence in a rotifer exoskeleton. With the 5x objective, we can see little dots swimming in what used to be empty space, but it’s hard to make out the details. When we move to the 10x objective, we can start to make out shapes of the Tetrahymena and more of the emptiness around them, but it’s difficult to see the exoskeleton.

Then as we start to go up in magnification, the details of the exoskeleton become clearer. It's cool to see more and more of those details as we zoom in. And especially when we get to the 100x objective, which gives us 1000x magnification, you can make out so much of the insides of the Tetrahymena, that they look like bags of very resilient bubbles.

Here’s another ciliate called a Pseudoprorodon that James looked at through all of these objectives. At first it just looks like a little green thing floating around and knocking into stuff. But as we go up in magnification, we can start to make out the subtle undulations of its body, which shifts the different shades of green.

And as we look even closer, the green itself takes on a new life, revealing the perimeters of the individual algae inside the pseudoprorodon. Revealing those details inside the tetrahymena and pseudoprorodon comes at a cost. We can’t see as much of the world around them, whether that’s the emptiness around the rotifer exoskeleton or the objects that the pseudoprorodon keeps bumping into.

Whether or not you need those details depends on what you’re trying to learn or what we are trying to show, and that’s why having the flexibility to look through a wider range of objectives is such an exciting upgrade for us. Objectives are our gateways to the microcosmos, and we’re excited to have all of these new scales to look at. We’ve also made some other upgrades so we can revisit techniques we used on our older microscopes.

Like a polarizer, because who doesn’t love this shiny, iridescent stuff? But we’re not just sticking with what we’ve known. Thanks to this upgrade, we’ve got a whole new way to look at cells: fluorescence microscopy.

And we are so excited for this one. The techniques we’ve highlighted so far are all clever manipulations of white light, a mixture of many visible wavelengths of light. But in fluorescence microscopy, instead of illuminating our sample with that mixture, we choose a specific wavelength of light.

That light is called the excitation light because, well, it excites certain structures based on their chemistry. And those excitable structures then emit some light of their own. The emission light will then travel back through the objective, get past barriers that filter out the excitation light, and then show up in our eyes as vivid color.

With our upgrade, we have four different wavelengths of light that we can use for fluorescence microscopy, and the parts of the sample that we see fluoresce will depend on which light we use. In this footage, we’re looking at the Pseudoprorodon that we saw earlier, only this time it’s being hit with 385 nanometer light. The red we see is the fluorescence from natural structures, this is called autofluorescence.

The rest of the organism is dark because it did not respond to that 385 nanometer light, making the color all the more vibrant. But the power of fluorescence microscopy is not just finding fluorescent structures that exist in nature. Chemists and biologists have developed all sorts of ingenious techniques to highlight different parts of cells using fluorescent dyes and proteins.

James is working on building up his arsenal of fluorescence microscopy tools and techniques so that soon, we’ll be able to dive even deeper into the microcosmos to seek out things that have been hidden from us before, uncovering the unseen world inside the unseen world that surrounds us Thank you for coming on this journey with us and thank you to Brilliant for sponsoring this episode. Brilliant features hands-on courses in science, math and computer science, and there you can learn everything from Astrophysics to Programming With Python. If all of that sounds like a lot to choose from and you need some help figuring out where to start, Brilliant has a bunch of curated Learning Paths where they’ve compiled courses into categories like “Science Foundations” and “College Mathematics” so you can make sure you’re taking all of the courses that will help you get where you want to go on your learning journey.

If you’re interested in learning more, you can get 20% off an annual premium subscription at Brilliant.org/microcosmos. The names that you’re seeing on the screen right now, they are our patrons on Patreon. And they’re the reasons that we’ve been able to stay on this journey for so long and also explore our world in such new and exciting ways.

We’re so excited to be using the resources from your patronage to do really cool things so that we can see deeper into our world. If you want to see more from our Master of Microscopes, James Weiss, check out Jam & Germs on Instagram. And if you want to see more from us, there’s always a subscribe button somewhere nearby