Physarum Polycephalum (slime mold) in UV

[Nemo Andrea]

Since Amoebozoa don't seem to have a natural category to slot into here, I figured I'd leave these images in this general topic area. Here some images of Physarum Polycephalum (a slime mold), that I keep at home for timelapses and macro photography. You can find some of my timelapses if you are interested on youtube

. It's a very interesting organism with perhaps its most amazing property of this macroscopic organism (easily fills a large petri dish) is a single cell (not single cell type, but single cell). If you are interested in Physarum, there are some nice reviews out there and http://slimoco.ning.com is a nice forum where all sorts of people talk slime mold stuff. I have also posted the UV image there for their enjoyment.

 

So, lets look at the visible first. You can see the characteristic yellow cytoplasm.

 

Let's look at the UV now. Physarum absorbs the UV quite strongly, which I guess is pretty typical. You can also see that the abandoned ''veins'' are not absorbing UV, showing as white.

 

Physarum has various blue and UV photoreceptors such as LOV-domain proteins and cryptochromes. It will also actively retreat (it is pretty quick for a single cell, moving at 1cm/hour if its in a bit of a hurry) from blue and UV light.

 

I might add an IR image to this post in the future, as I have not taken an IR image of physarum yet.

 

If you have any interesting ideas for further imaging stuff related to UV with this, let me know. Might be some interesting timelapses possible. Since it actively avoids UV I don't think any macro work will be possible, but some kind of UV timelapse at lower mag might be somewhat interesting...

[eye4invisible]

Very interesting. An IR image would be cool, I'm sure.

[Nemo Andrea]

Alright, here a picture in IR (720nm+) using my Kolari Vision IR 720nm.

 

I suppose 720nm is not so interesting for this organism. It would be very interesting to do a 590nm+ filter image. Some of the far red sensors might change the appearance a bit, but I don't expect so. Still, i'll be sure to try that once I have such a filter. The two phytochromes that might be present in Phyasrum have peak excitation at ~680nm and ~750nm. I suppose they are such a tiny fraction of the cytoplasm makes absorption due to these molecules not visible. That or the wide spectral range recorded simply makes it unnoticable. Supposedly it is measurable with the right kind of equipment: https://onlinelibrar...24LIIFOT2.0.CO2. (Kakiuchi, Yasutaka, et al. "Light Irradiation Induces Fragmentation of the Plasmodium, a Novel Photomorphogenesis in the True Slime Mold Physarum polycephalum: Action Spectra and Evidence for Involvement of the Phytochrome." Photochemistry and photobiology 73.3 (2001): 324-329.)

[Andrea B.]

Completely fascinating! Thank you so much for posting this.

 

My first encounter with a slime mold was a very puzzling one as I could not figure out why or how the mass had moved across the old tree stump I had found it on. But that led to a bit of internet prowling and I learned more about these interesting life forms. And just now I looked in the usual place - Slime Mold - and learned that the classification of slime molds is still ongoing. Some are amoeba like and some aren't, to oversimplify, but they definitely are no longer considered fungis. I can see how an entire career of research could happen when studying these interesting organisms!

 

I am wondering if any of the slime molds fluoresce?

 

What is the white rectangular material in the photo? Is that PTFE used for white balance?

 

It is an interesting question as to where Slime Mold would be placed as a formal entry here on UVP! I could create a Category labeled "Other" if we get more such entries.

[Andrea B.]

P.S. I'm impressed by the Slime Mold Forum linked above. It's very nicely done.

[Nemo Andrea]

Completely fascinating! Thank you so much for posting this.

 

My first encounter with a slime mold was a very puzzling one as I could not figure out why or how the mass had moved across the old tree stump I had found it on. But that led to a bit of internet prowling and I learned more about these interesting life forms. And just now I looked in the usual place - Slime Mold - and learned that the classification of slime molds is still ongoing. Some are amoeba like and some aren't, to oversimplify, but they definitely are no longer considered fungis. I can see how an entire career of research could happen when studying these interesting organisms!

 

I am wondering if any of the slime molds fluoresce?

 

What is the white rectangular material in the photo? Is that PTFE used for white balance?

 

It is an interesting question as to where Slime Mold would be placed as a formal entry here on UVP! I could create a Category labeled "Other" if we get more such entries.

 

The white material is indeed PTFE, for white balance in theory.

 

The slime mold has some interesting (auto)fluorescence when illuminated with 488nm laser. I have not tried macroscopic fluorescence yet; don't have the gear for that currently. Some slime mold species have iridescent spores, which is also neat (see: http://slimoco.ning.com/photo/elaeomyxa-cerifera-1b-centrecrop1000-watermark?context=latest).

[Andrea B.]

The white material is indeed PTFE, for white balance in theory.

 

Even if we don't white balance our false colours, the PTFE (or other UV reflective standard) also helps to indicate the tonality of the photo. This is good documentary practice.

 

Did you get some interesting comments on your UV post in the Slime Mold Forum? I got so interested in all the stuff there, I forgot to look up your post!