Lilium pollen green fluorescence

Pau · Post by **Pau** » Tue Jul 11, 2017 7:04 am

Playing with my LED illuminator, I've found blue excitation and green emission to provide the best results with this subject.

I also discovered a weird effect: Inversely to the normal phenomenon called photobleaching or just fading the green emission highly increases over the time exposed to blue excitation to the point of ruining a stack done with high NA objectives. This must be due to something happenig inside the pollen cells because this is where fluorescence increases, not so much at the exine. Any info about it would be most interesting.

1. 10/0.30 Pl Fluotar, somewhat cropped

2. 40/0.65 old short barrel Nikon Plan "No cover glass"

3. Stereo pair of the former image, hope it will work right for people able to cross eyes, inverted it looks OK with a mirror viewer.

ChrisR · Post by **ChrisR** » Tue Jul 11, 2017 10:12 am

Intriguing. I wonder if bees can see it in sunlight!
The stereo works very well.

Did you go pollen collecting ?

JH · Post by JH » Tue Jul 11, 2017 10:24 am

Very nice
Regards Jörgen

Jacek · Post by **Jacek** » Tue Jul 11, 2017 11:58 am

First super !
Are these pollen lilies?

Cactusdave · Post by **Cactusdave** » Tue Jul 11, 2017 1:30 pm

The major pigment in lily pollen is a carotenoid, alpha-carotene 5,6-epoxide http://onlinelibrary.wiley.com/doi/10.1 ... 395.x/full Carotenoids are known to produce a green fluorescence. When excited in the blue (450-510nm) they emit in the green with a maximum around 560nm. https://link.springer.com/article/10.10 ... 010-9505-y The quantum yield for carotene is very low compared with chlorophyll, meaning it is usually masked by the red chlorophyll emission in chlorophyll containing plant tissue. In carotenoid containing pollen grains it is the only fluorophore and is easily visible. I would expect other yellow or orange pollens from other plants where carotenoids are the source of the colour to behave similarly

Pau · Post by **Pau** » Wed Jul 12, 2017 12:27 am

Thank you all for your comments.

- Chris, I don't think bees could be attracted by green light...leaves are green
Lilium decorative cultivars produce high amounts of pollen, I made a dry uncovered slide with pollen of four anthers carefully flattened to reduce stack depth and to allow using short WD objectives.

- Jacek, yes, Lilium is the genus name of lilies

- Dave, you put me in the right way about carotenoids although after some further search I still can't find any direction about the weird effect observed., thanks again. Will test with other species.

zzffnn · Post by **zzffnn** » Wed Jul 12, 2017 6:48 am

Pau,

You may want to try google image "carotenoid green fluorescence time" or something similar, and add keywords to limit results if you want. You will find many figures and papers to read through.

I read the first likely paper (based on its figures) but did not find anything. They used additional treatments that did not occurred in your work.

Maybe some degradation product of carotenoid, induced by blue light, can produce stronger green fluorescence. Maybe some other mechanisms...........

Very nice images!

carlos.uruguay · Post by **carlos.uruguay** » Wed Jul 12, 2017 6:52 am

Excellent

fpelectronica · Post by **fpelectronica** » Wed Jul 12, 2017 7:46 am

Very nice

Charles Krebs · Post by **Charles Krebs** » Wed Jul 12, 2017 8:57 pm

Really nice. Interesting fluorescence.

The lilies are really out here this year... might have to take a look!

Sumguy01 · Post by **Sumguy01** » Wed Jul 12, 2017 9:02 pm

Nice.
Thanks for sharing.

Marek Mis · Post by **Marek Mis** » Wed Jul 12, 2017 9:29 pm

Very nice and very interesting !

Marek

Pau · Post by **Pau** » Thu Jul 13, 2017 4:27 am

Thanks all for your kind comments, and specially to Charles and Francisco who actively helped with my setup

Fan: I've googled pretty intensively and I've read several articles with no luck. Because the phenomenon is so evident and strong likely what I need is the right term to search