About BRS's peridinin data

[Erasmus Crowley]

In some of videos by @Bulk Reef Supply regarding light spectrum, they used an image that illustrated the absorption spectrum of the accessory pigment peridinin.

Today I noticed that the majority of the images that I can find that seem to show the same data are very different from BRS's data. Can someone clarify for me what is going on here?

This is BRS's peridinin-chlorophyll-protein absorption data image from their videos. Notice the very understated green absorption around the 520nm range.

This is a similar image that I took from a scientific paper that I found.

Notice the much stronger green absorption, specifically at 520nm. The 520nm absorption seems like it is actually higher than the 420nm is. The 550nm light is just as high as the 400nm light. This is what most of the images that I can find on the internet look like.

So which of these is closer to the truth? Or is there some nuance here that I'm not understanding?

If BRS data regarding peridinin isn't accurate, then shouldn't their "Biology Band" include the green spectrum between 484nm and 550nm?

 

[Manny’s Reef]

I don't have an answer for you but I did want to comment that Ryan could at least learn how to pronounce the word correctly if he's going to use it over 100 times in a single video.

 

[C4ctus99]

Does BRS have any links or cite any sources on their information?

 

[Hooz]

I'm just posting so I can follow along. I'm popping my popcorn now.

@luxdium

 

[C4ctus99]

I'm just posting so I can follow along. I'm popping my popcorn now.

@luxdium

Same tho

 

[Hooz]

I will add that I am a HUGE fan of the "biology band" concept. I've been running LuxEngine upgrades (widest blue band on the market?) for over 2 years now, so I appreciate that everyone else is catching up. I think it will eventually push manufacturers in the right direction ... BUT ... I'm not sure I agree with the range of BRS' band, and I'd like to know what they based it on, more than just "most experts can agree".

 

[Crustaceon]

Suddenly, the entire reefing community is inundated with pics of tanks with that washed out "kermit the frog" look from green led-swapped fixtures and green spectrum tuning software updates on the fancier stuff.

 

[Dburr1014]

In some of videos by @Bulk Reef Supply regarding light spectrum, they used an image that illustrated the absorption spectrum of the accessory pigment peridinin.

Today I noticed that the majority of the images that I can find that seem to show the same data are very different from BRS's data. Can someone clarify for me what is going on here?

This is BRS's peridinin-chlorophyll-protein absorption data image from their videos. Notice the very understated green absorption around the 520nm range.

This is a similar image that I took from a scientific paper that I found.

Notice the much stronger green absorption, specifically at 520nm. The 520nm absorption seems like it is actually higher than the 420nm is. The 550nm light is just as high as the 400nm light. This is what most of the images that I can find on the internet look like.

So which of these is closer to the truth? Or is there some nuance here that I'm not understanding?

If BRS data regarding peridinin isn't accurate, then shouldn't their "Biology Band" include the green spectrum between 484nm and 550nm?

Very interesting.
Perhaps @Dana Riddle would be the guy that knows best?

 

[Erasmus Crowley]

Ok. I can shed some more light on this mystery.

When the absorption spectrum of a pigment is measured, the pigment is extracted from the tissue of the living thing (in this case zooxanthellae), and then suspended in a solvent. The light absorbed by the pigment depends on which solvent it is suspended in.

I was able to find this paper which included the following image.

If you look closely at the dotted line which represents "Peridinin in n-hexane", it is an almost exact match for the spectrum data used by BRS.

So I'm guessing this solvent was used wherever they sourced their data.

So this leads directly to another question. Which of these solvents gives us the most accurate simulation of the spectrum that coral are able to use for photosynthesis in their tissue? Was using the n-hexane solution the best choice that they could have used?

 

[Erasmus Crowley]

I'm going to attempt once again to answer my 2nd question...

After re-reading the text of the first study that I linked to in my opening post, I stumbled across this in the text just prior to the image that I included.

"The absorption spectrum of peridinin in the polar and viscous solvent ethylene glycol, which most closely mimics the shape of the peridinin absorption spectrum in PCP, is also shown in Fig. 1."

So if I'm interpreting that correctly, this text seems to say that the solid line in that first non-BRS image that I shared is the actual absorption of peridinin as it exists in the tissue of coral. If that is true, then I think this provides a solid reason that this is the spectrum that should have been presented in the video, and also that the cyan spectrum and much of the green spectrum should have been included in the Biology Band.

It's relevant to this thread (and quite frustrating) that in the BRS video uploaded just today Ryan said "Green really has limited photosynthetic value".

I suspect that if he were to see the correct spectrum data, then he might change his mind about that.

 

[oreo54]

Ok. I can shed some more light on this mystery.

When the absorption spectrum of a pigment is measured, the pigment is extracted from the tissue of the living thing (in this case zooxanthellae), and then suspended in a solvent. The light absorbed by the pigment depends on which solvent it is suspended in.

I was able to find this paper which included the following image.

If you look closely at the dotted line which represents "Peridinin in n-hexane", it is an almost exact match for the spectrum data used by BRS.

So I'm guessing this solvent was used wherever they sourced their data.

So this leads directly to another question. Which of these solvents gives us the most accurate simulation of the spectrum that coral are able to use for photosynthesis in their tissue? Was using the n-hexane solution the best choice that they could have used?

huh, interesting.
you might find some in situ measurements related though this is really all pigments.

The methanol one is interesting.. see "b"

 

[oreo54]

Absorption spectra of the PCP complex (solid line), Chl-a in diethyl ether (dashed line), and peridinin in ethylene glycol (dotted line).

 

[Erasmus Crowley]

Absorption spectra of the PCP complex (solid line), Chl-a in diethyl ether (dashed line), and peridinin in ethylene glycol (dotted line).

It looks like your image tag didn't work.

 

[oreo54]

It looks like your image tag didn't work.

Yea working on it .

https://www.researchgate.net/profile/Tomas-Polivka-3/publication/10987676/figure/fig4/AS:668737896189953@1536450947244/Absorption-spectra-of-the-PCP-complex-solid-line-Chl-a-in-diethyl-ether-dashed-line_Q640.jpg

Oops same one as your post #1

 

[C4ctus99]

So what I’m gathering from this is that there may actually be a photosynthetic benefit from green light specifically with peridinin?

 

[taricha]

If you look closely at the dotted line which represents "Peridinin in n-hexane", it is an almost exact match for the spectrum data used by BRS.

So I'm guessing this solvent was used wherever they sourced their data.

Nice detective work!

So what I’m gathering from this is that there may actually be a photosynthetic benefit from green light specifically with peridinin?

Yep. Whether you look at absorbance of coral/ symbiont...

... or you look at an action spectrum (plot of the amount of biological response due to a wavelength of light)...

Either way, you'd conclude that the range of 480-520 nm is a perfectly good color of light for corals to use. Not as crucial as blue, but totally usable.
(Charts from Dana riddle articles. )

 

[C4ctus99]

Nice detective work!


Yep. Whether you look at absorbance of coral/ symbiont...

... or you look at an action spectrum (plot of the amount of biological response due to a wavelength of light)...

Either way, you'd conclude that the range of 480-520 nm is a perfectly good color of light for corals to use. Not as crucial as blue, but totally usable.
(Charts from Dana riddle articles. )

Maaaaan… there was a thread where a whole bunch of people were arguing with one guy over grow lights

@MoshJosh was on that thread too

 

[MoshJosh]

I bought a grow light and am testing now haha!!!

My impressions after a week are. . . good polyp extension on the "easy" SPS I added (stylo and monti). OK polyp extension on my goni (but they never thrived in this tank regardless of light). Duncan and Zoa's not liking it so much, but to be fair they may have been too close to the light. I moved the duncan down a few inches to see if it likes it better. . .

Beauty is in the eye of the beholder but DANG are they ugly in this light haha

 

[taricha]

I'll just add that there are lots of reasons to use our not use wavelengths of light. Photosynthesis by corals isn't the only consideration.
Light shapes the community of what else grows.
Also, if you use a lot of 500-520nm green, the fluorescence of corals GFP might be hidden a bit.

 

[Hooz]

So I just watched the latest BRS video (released yesterday) and they're calling the "wide blue band" from 390-490nm now. That lines up much better with studies I've seen, and what I'm shooting for in my own tanks.