I had the opportunity last week to present in front of few dozen industrial scientists visiting stanford. The catch was I only had less than 10 minutes!

If I had to share one way that the foldscope really has changed the way I think about life :

I’d choose the fact that it provides a window into the physiology of tiny living organisms; their beautiful motions, dances and flows-a visceral reminder of the hallmark of life – that it is animate!

So, naturally I wanted to share this subtle, but personally important point. There were small challenges- preparing wet mounts, keeping organism alive and making sure the live projection from my iPhone to the big screen worked.

I took the risk (I had a couple backup slides) and everything turned out well. I’m sharing the video and a few images below in the hope of encouraging others to also share live demos; its tricky, requires preparation, but totally worth it!

Dive in!

Note: the larvae is of Culex tarsalis. I may have bungled up the name in the heat of the moment.

And here is one more picture from the event.

So what’s inside the pus liquid?

Let’s find out.

Here’s a slide with a sample of pus.
Here’s a first look under the scope.

All those tiny cells are dead white blood cells (leukocytes). The irony is not lost on me, that in my previous post I was hunting for white blood cells, and here i have thousands of them – dead!

I also hoped to see some bacteria but couldn’t find any. I did find clusters of dead skin cells (i think?). However, no nucleus was observable in the cells – so it could just be an artifact.

I will hunt more carefully around and see if I can find any bacteria in this liquid. It smelled quite bad, so i am certain they are there – but again hidden from plain sight and need to be revealed.

In any case, the pus liquid made some nice patterns as it dried and here are a few. Even a seemingly disgusting and yucky liquid seems cannot help itself but obey the capillary forces..

This is a second part of exploring what lies in our bodies using the foldscope. Apart from the obvious utility in seeing what we’re made off, I also think this is a useful collection of experiments that you can use at any place or time for a quick foldscope demonstration. The last experiment was with cheek cells. This post is on looking at blood and hunting for white blood cells…

The first step is to use a sterile lancet on your finger and generate a tiny droplet of blood (proceed with caution at this step and conduct this step under adult supervision).

The next step is to transfer the blood onto a clean slide and create a smear. See video below.

I put a cover-slip on the slide and this is how the slide looked before mounting onto the foldscope.

Under the foldscope, you see hundreds and thousands of red blood cells (RBC’s). It’s amazing how many of them are in a teeny tiny drop of blood.

Now, we wanted to hunt for white blood cells – these are fewer in number and thus harder to find. One trick we used next is to stain them with Methylene blue solution. The idea is that the methylene blue dye would stain the cytoplasmic material in the white blood cells, and they would appear blue amidst a sea of red blood cells. This is akin to a game of ‘Where’s Waldo’ – and we use a trick to color Waldo blue so it becomes trivial to locate him..

The way we did it is to first fix the cells with methanol (you could potentially use ethanol from a local drugstore too): after creating a smear, we air-dried it for a few minutes, and then added a few drops of methanol and let it evaporate (2-3mins). Once the methanol had evaporated, we added a few drops of methylene blue (you can find this online easily). We let it sit for about 5 mins. Then washed the slide off under tap-water.

After covering the smear with a cover-slip, we mounted it under a foldscope. In the next video, in the first few frames, we believe we saw a stained white blood cell in the top-left corner.

One thing became apparent very quickly that there are far more red blood cells than white blood cells – and we only could see some bluish shapes here and there – that is why this post is titled a hunt for white blood cells – they are elusive and tricky to find at a first-try.

Here’s another video where we scan the smear – take a look.

This excercise imparted a few thoughts on my mind. For disease diagnostics, looking at a smear under a microscope can be challenging if you are looking for white blood cells or parasites. Hence staining well is a very useful trick to know, especially if one has to eliminate false-negatives. This also impresses the importance of centrifugation to remove the RBC’s from the picture – to really be able to separate out the objects of interest from the red blood cells.

Hopefully, if you are out in the field, in a class-room or at home demoing the foldscope, in addition to cheek cells, now you have a second easy sample to quickly prepare and share with others, the wonders of the micro-cosmos of you own body.

It’s always fun to revisit simple experiments and test it out with the foldscope. In this post, I wanted to see my own cheek cells. Now, if you search on the microcosmos website, you’ll come across many posts on cheek cells, but I hope to share one interesting insight, making the case that it’s worthwhile re-doing something others have done- you never know what you’ll find!

This experiment is very simple. Find a bamboo/plastic toothpick. Scrub your inner cheek for ~20 seconds. Rub the toothpick on a slide and cover with a cover-slip. Thats it!

Here’s the first thing I saw. Plenty of cheek cells!! Very clear and beautiful. If you look carefully, you should see the circular nucleus in the center.

Now, here’s where it becomes interesting. Looking carefully, I could convince myself that the tiny ‘dots’ were actually bacteria – it wouldn’t be surprising – our mouths are filled with microorganisms. So, I decided to take some videos.

In this video, the first thing that amazed me was the large no. of cheek cells. I wonder if thats why a cheek swab is used to obtain dna for testing – there should be plenty of DNA to get a good read.

Here’s where I first observed a moving microorganisms. We thought its a bacteria – but I find it hard to believe. I wonder if its a Spirochaete? I know Manu has a post on them in his teeth scrapings..

Now Josh and I got pretty excited – in the next video, you can again make out moving tiny dots and rotating specks.

And this is the final longer video – I’ll leave it to you to find all the tiny moving bacteria in this video – and convince yourself that indeed, you’re mouth is teeming with all kinds of little creatures.

The point of this simple post is that many of you would have seen cheek cells in high school. However, I posit to you that doing it yourself is a rewarding exercise, specially with a foldscope. Even though you know what to expect, the foldscope lowers the discovery barrier in a marvelous way enabling you to make your own unexpected observations.

Last but not the least, cheek cells, and finding bacteria is also a simple experiment to practice your foldscoping skills. Because practice makes perfect!

I’ve always wanted to see bacteria through the foldscope. As obvious as it may be, I’d never seen bacteria in decomposing matter with my own eyes.

So, after a plant in my house died, I put it a jar and let in decompose for a week in tap water. I took a drop out, and here’s the first glance I saw.

I’m sharing this so fellow explorers don’t give up at this point. I zoomed in further using my phone screen, and started to make out tiny dots had shapes to them. Getting exciting now.

Some of the rod shaped ones could be E. Coli.

Now, comes the part where I had to convince myself that they were indeed alive. And moving. So I placed the video mode. And patiently waited. Ssh. Holding my breath.

It was super cool to see them slow wiggle around. I couldn’t believe my own eyes.

Here’s another peek into their little world. It’s a like literally peeking into a different time zone. They seem to be just hanging out.

To see the motility of these tiny creatures, I created a timelapse.

This video makes me super satisfied today. There is something to spectacular about knowing something in theory and then experiencing it with your eyes.

If you can identify the bacteria based on their shapes/motility, please share in the comments below.

I started my first ciliate culture today. Here’s a first peek at the culture- you should notice tiny bacteria swimming around and some hay.

I quickly spotted my first ciliate – this is a paramecium  – as can be identified by its characteristic ‘slipper’ shape. You can clearly see the hundreds of cilia lining its edges and beating to an invisible tune. See if you can find the following : 1. Oral groove. 2. Food vacuoles at the base of the oral groove (gullet) — it appears to ‘pop’ or deflate at 13s, 20s and 28 s. You should also notice the tiny moving things inside the paramecium as well as outside – at one point one of them gets trapped in the cilia (on the lower side of the paramecium).

I was initially sad that the paramecium just remained stuck in one spot – but lo and behold, it started to move and make strange twisting motions. I am amazed at the shape of its body – and kept staring at this video for over and over again.

And then as a fish takes to water, it decide to do long ‘laps’. It was just swims around like a microscopic fish – what a pleasant sight! I had so much fun watching it glide along, then change direction. I’m thinking about the whiplash movement created by the cilia as they change directions – going from the power stroke to the recovery stroke.

I was looking around for didinium’s and scanned the rest of the slide – and happened upon this happy camper. My initial reaction was that this might be a didinium cyst – but on second thought I think it is a volvox (flagellate, not a ciliate) since I can also identify the small asexual daughter colonies inside. If you have a better idea, please let me know.

And finally – the ciliate I had been hunting for – didinium. It gave me a glance and disappeared from view. It is incredible how fast it swims and zig-zags around.

I have a culture going and will proceed with a hay inoculation as described by Laks in a previous post – looking forward to cultivating my own ciliate pets – and hopefully making a longer movie with the didinium’s.

So Wired magazine has a post on the DFD videos.. The reason I posted is that it explains what the Milton van Dyke award means, and the connection to the scientist himself, which is cool.

Enjoy!

Link here.

It’s finally fall in California. And the leaves are falling. I couldn’t help but ask myself some questions about why and what causes the leaves to fall. In addition, they were changing colors as well, so I wondered if they changing colors would reveal a changing morphology or indicate a predominantly compositional change.

So I took the following leaves and put one under the foldscope. Since they were half and half, I was hoping catch a spatial variation in the same leaf.

I spent quite some time looking at the leaves and my conclusion is that there is no morphological difference between the green and yellow parts. See for yourself below.

The left side is the green and right is the yellow. Based on my observations, I’d conclude that changing color is a predominantly chemical change (pigments is my guess) and has negligible morphological effects, at least at short timescales. Perhaps later, desiccation would lead to buckled cells.

So to the next question. How do the leaves fall? I observed something interesting on the stems. Here’s a small bit cut out and mounted.

If you look carefully in the above picture, you will observe two dots that look like eyes. I suspect that they are vessels or veins that transport liquid to the leaf. So now I can start making a hypothesis. When the human body becomes cold, it cuts off blood supply to exterior parts as a survival mechanism- perhaps plants respond in the same way. So, the indication to changing color, could be coming either by reduction in water/nutrients through these vessels, which would trigger the leaves to change color and also create desiccated ‘joints’ that would easily break under the slightest mechanical force (wind/gravity).

Here’s the vessels under the foldscope. (Top-view)

And a side view indicating that they run through the entire stem.

And now for some fun videos.

The first one shows how easily the leaves break. I have to barely touch them. And if you look closely, you’ll see the ‘eyes’ or the vessels that I’m now convinced are the water/nutrient pipeline.

Now watch the same breaking for leaves that are partially green. I almost have to tug at them to free them. Notice the ‘eyes’ are not as easily visible.

The last aha moment. The base of the stems in the partially green leaves is still moist and so a darker color. You can barely see it. However you can clearly see the stem and the vessels in the dried versions as they have desiccated and are more yellow.

So I think my hypothesis of the plants cutting supply off has some merit.

I’m quite sure there is a more complicated story behind, but I’m willing to bet that we understood in broad strokes the gist of how and why leaves fall in fall, by just observing closely.

And isn’t that just a wonderful way to learn?

Unfortunately I couldn’t make it to the meeting this year due to personal reasons, but I am thrilled to be selected, specially given Milton van Dyke’s long history at Stanford, and of course the album of fluid motion, which truly inspired me (and countless others) to the beauty of fluid dynamics!

If you haven’t seen the video, check it out to find out what the fuss is all about : )

Video Link

From the same Hopkins trip where I found the nudibranch eggs, I also was able to find Copepods swimming in the ocean water sample.

I took two videos exactly and couldn’t make head or tail (literally) of the Copepods. I left the videos on my phone and forgot about them, until right now. I’m sure you have a similar experience where you stick something under the foldscope but don’t ‘learn’ anything per se from the experiment.

Today, I came across this book from the stanford library and I was leafing through it and saw the following images.

Page 148 describes Copepods and the caption says that female Copepods can be distinguished by the presence of egg sacs near the tail. And there is the following image on page 149.

As soon as I saw these images, a bulb went off in my brain. I recalled seeing something similar. With my own eyes !! So I pulled out my phone and was able to find the following two videos which in my mind I has written off as ‘meh, not interesting‘, perhaps because I was just exhausted that day after hours of foldscoping

So, clearly what I was observing were the beautiful egg sacs on a female copepod.

The lesson here, at least for me, is that sometimes it’s easy to think that just because you see through a foldscope, you’ll learn instantly or not learn something. Sometimes it takes time to make the connections.

So, be patient, and keep exploring.