Infinite Fluorescence

[rjlittlefield]

I just found this article as well, which covers the different water-based shooting mechanisms used by plants and fungi.

https://journals.plos.org/plosone/artic ... ne.0158277

Excellent! I did not know that article.

--Rik

[Pau]

Thanks Rik, that’s fascinating stuff, something I hadn’t been aware of and explains the need for the obvious strength of the annulus structure. I just found this article as well, which covers the different water-based shooting mechanisms used by plants and fungi.

https://journals.plos.org/plosone/artic ... ne.0158277

David

Interesting paper, thanks for the link.
I've found very surprising that Ecballium elaterium, a well known plant presenting one of the more spectacular seed shooting mechanisms was not cited.

[iconoclastica]

Male Fern Dryopteris filix-mas spore - in brightfield and UV

That is a very good spore photo (left). Strange, how the folds look much thinner than in UV and on SEM-photos.

[micro_pix]

.
Thanks,

I don’t know much about electron microscopy but I’m guessing that its beam doesn’t penetrate the surface so shows the outer surface as undulated and solid and doesn’t show that it’s a very thin wrinkled perispore covering a smooth round spore. My thinking is that the light microscopy gives a better interpretation of the structure - I’ve noticed the same thing in fungal spores that have thin perispores around them.

David

[iconoclastica]

source: Tryon AF & B Lugardon. 1990. Spores of the Pteridophyta: Surface, Wall Structure and Diversity Based on Electron Microscope Studies. New York, and Berlin; Springer-Verlag.

I recognize the "inflated folds" in the fluorescent image, but less so in the brightfield image. I suppose the reason has to to with the amount of wall material perpendicular to the image plane. Next time I'll make spore photographs I will make sure to study the depth maps too.

[micro_pix]

I recognize the "inflated folds" in the fluorescent image, but less so in the brightfield image. I suppose the reason has to to with the amount of wall material perpendicular to the image plane. Next time I'll make spore photographs I will make sure to study the depth maps too.

Yes, and a transparent or almost transparent surface in brightfield would be shown as a solid surface in the electron microscpoe.

The brightfield and fluorescence image were of the same spore taken by the same objective at pretty much the same time. The light intensity was much less in the fluo image and of course the origin of the light is very different. In the fluo image we are only seeing light emitted by molecules excited by the UV whereas in the brightfield image we are looking at the variation of intensity and colour of the transmistted light that has passed through the object.

I don’t have any experience with fern spores but I have a fair amount of experience with fungal spores. In-species variation, maturity, the state of hydration and the medium they are in can make quite a difference to the size and appearance of the spores and I read that there is a lot of in-species variation in ferns and I don’t think these were fully mature spores.

I thought that the need to dehydrate the specimen and put it in a vacuum was partly responsible for some of the differences in appearance in electron microscopy but I notice with pollen that electron microscopy also shows 3 dimensional aspects that are not apparent at all in brightfield or reflected light. I suppose, for I.D. purposes, it makes sense to compare images taken by the same technique, in the same medium. For fungal spores I would measure at least 20 in a sample to get an average size and, with ornamented spores, I would look at a fair few to get an idea of the average ornamentation, as it can vary quite a lot between individual spores in the same sample.

David

[iconoclastica]

For SEM, spores are not dehydrated. They are by nature in that state. I never heard they get deformed in the process. The wall material is exceptionally hard. For taxonomic purposes SEM photos are excellent since the smallest details show up. For recognition the SEM photos have limited value since few people have access to SEM facilities. Therefore I prefer good optical photos. As it appears, it's a bit hard to interpret the SEM imagery when you are seeing the optical image.

It is true that fern spores rapidly change size in various embedding media. The bad thing is that researchers and descriptions often list the spore size ranges without telling in what medium the measurement has been made. As soon as I will have a little more time, I'll redo measurements for our ferns in water, so everyone can use the figures.

I know use ImageJ to measure the spores. That introduces an error for it only partially distinguishes spores in wrong positions. But when I measure them hand-picked by the micrometer, some must be slightly out of plane to and I don't know what bias I create by not selecting them arbitraily. Also measuring by hand is so entiring that I hardly ever reach 20 spores before fatigue hits my eyes, whereas in the automatic procedure there are easily as many as 70 or 80 in the sample. That averages away a lot of imperfect measurements.

Perhaps your spores were a bit youngish indeed. The irregularity in the split-sporangium photo is striking, but not so much as to suspect misshapen spores, such as hybrids have. They also look somewhat flattened.

[carlos.uruguay]

Marvelous!!!

[micro_pix]

Thanks Carlos!

Perhaps your spores were a bit youngish indeed. The irregularity in the split-sporangium photo is striking, but not so much as to suspect misshapen spores, such as hybrids have. They also look somewhat flattened.

Many thanks for all that. I use Piximetre http://www.piximetre.fr/ for spore measurement, it's free and easy to use once you've calibrated your objectives.

I will keep an eye on the fern and get a selection of mature spores from a couple of different plants in the garden and have a look. Since there is so much bracken around here too I was going to try and find some bracken spores, I read they only produce spores occasionally.

David

[iconoclastica]

I use Piximetre http://www.piximetre.fr/ for spore measurement, it's free and easy to use once you've calibrated your objectives.

I'll be sure to try that (once relieved from my pesent deadline ). Thanks,

Wim

[micro_pix]

.

Just for completeness Here are a selection of mature spores from the same Dryopteris filix-mas. They do look more like the SEM images. These were in water with brightfield illumination using a lower NA objective than the previous spore image and focussing on imaging the surface ornamentation of the perispore.

David

Dryopteris filix-mas spores in water.

[iconoclastica]

Excellent !

[micro_pix]

Thanks Wim.

I now understand what you were saying about the shape of the other spores. No idea if they were just contorted, immature or it was a result of something I had done but thanks for drawing my attention to it.

David