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Dear Dr. Murray,
<br> thank you very much for your posting. So, here comes
the reasoning against photoprotection function of fluorescent pigments
from corals. These pigments are (in the majority of cases) proteins homologous
to green fluorescent protein (GFP) from Aequorea victoria, as we recently
found out (Matz et al, Nat.Biotechnol. 17: 969-973, 1999).
<br> We already had a bit of this discussion with prof.
Ove Hoegh-Guldberg of the University of Queensland (oveh@uq.edu.au), who
was also suggesting photoprotection as the major role of fluorescent proteins.
Here is a part of what I wrote to him directly in responce:
<p>Concerning photoprotection I would rather disagree with you. First of
all, corals possess a multitude of low-molecular sunscreen
<br>compounds for this purpose (see, for example, Dunlap, W.C. et al. Nature's
sunscreen from the Great Barrier Reef, Australia. International Journal
of Cosmetic Science 20, 41-51 (1998)), so additional recruitment of specialized
proteins
<br>for the same purpose seems rather tedious. Still, if it still was protection
from UV, there is no difference which
<br>fluorescent color to use - green or red, they are both UV-excitable.
Meanwhile, our most recent data on molecular features of red-emitters suggest
that they are advanced versions of greens, so that a point mutation would
most likely damage
<br>the red protein making it green. Therefore, red color should have some
special role in nature (different from green!)
<br>to be maintained by natural selection, otherwise all the red-emitters
would have long since deteriorated into greens due to mutation pressure.
In addition, red-emitters are heavily suboptimal in comparison to greens
in terms of photoprotection - they all have much lower quantum yields of
fluorescence.
<p> So, I think that the coral fluorescence file is still
far from being closed.
<br> I would be happy to continue this discussion, especially
taking in account that the question of the fluorescent proteins function
in corals is exactly the subject of my current research.
<p>sincerely yours
<p>Mikhail Matz, Ph.D.
<br>Institute of Bioorganic Chemistry
<br>Miklukho-Maklaya 16/10
<br>117871 Moscow, Russia
<br>
<p>Robert Murray wrote:
<blockquote TYPE=CITE><style></style>
<font face="Arial"><font size=-1>Hi
Iain et al,</font></font> <font face="Arial"><font size=-1>Coral photobiology
is not my area of study, although I did examine the topic some years ago.
I believe it is fairly common for many corals to exhibit brightly coloured
fluorescence pigments (especially those in shallowest water conditions
where light intensity is greatest).</font></font> <font face="Arial"><font size=-1>From
some of the literature I have read I seem to remember a plausible case
for these pigments operating as some sort of protection against the destructive
energy of short (UV) wavelengths, by liberating some of this energy as
harmless (less energetic) visible fluorescence. Perhaps this is one of
the discredited theories now. If so, I would be interested to hear the
evidence against it.</font></font> <font face="Arial"><font size=-1>Regards
to all</font></font> <font face="Arial"><font size=-1>Robert Murray.</font></font> <font face="Arial"><font size=-1>(What's
up Iain?)</font></font> =======================
<br><font face="Arial"><font size=-1>ROBERT MURRAY BSc, FGA,</font></font>
<br><font face="Arial"><font size=-1>Discovery Bay Marine Laboratory,</font></font>
<br><font face="Arial"><font size=-1>Discovery Bay, Jamaica, W.I.</font></font>
<p><font face="Arial"><font size=-1>Tel. (876) 973 2946</font></font>
<br><font face="Arial"><font size=-1>Fax. (876) 973 3091</font></font>
<br><font face="Arial"><font size=-1><a href="mailto:rmurray@infochan.com">rmurray@infochan.com</a></font></font>
<br><font face="Arial"><font size=-1><a href="http://www.DBML.ORG">WWW.DBML.ORG</a></font></font>
<br>=======================
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style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
<div style="FONT: 10pt arial">----- Original Message -----</div>
<div
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><b>From:</b>
<a href="mailto:matz@ibch.ibch.ru" title="matz@ibch.ibch.ru">Mikhail Matz</a></div>
<div style="FONT: 10pt arial"><b>To:</b> <a href="mailto:I.Macdonald@mmu.ac.uk" title="I.Macdonald@mmu.ac.uk">Iain
Macdonald</a> ; <a href="mailto:coral-list@coral.aoml.noaa.gov" title="coral-list@coral.aoml.noaa.gov">coral
list</a></div>
<div style="FONT: 10pt arial"><b>Sent:</b> Tuesday, July 25, 2000 11:33</div>
<div style="FONT: 10pt arial"><b>Subject:</b> Re: Orange Montastrea cavernosa
recruits?</div>
Hi Iain,
<br>we know a little bit what is the substance causing the fluorescence
in
<br>corals,
<br>and observations, measurements and photos were made about this
<br>(see <a href="http://www.nightsea.com/references.htm">http://www.nightsea.com/references.htm</a>
for the list of related
<br>papers and websites)
<br>Moreover, in particular M.cavernosa fluorescence was measured (in situ)
<br>by Charles Mazel
<br>and is studied by me (in vitro) right now.
<p>However, so far we have absolutely no clue as to the function of this
<br>fluorescence in
<br>nature (if we forget for a moment about older hypotheses all of which
<br>seem wrong by now),
<br>and the subject is my primary interest. Your observation is, as far
as I
<br>know, the first
<br>information which might help to link fluorescence to some aspect of
coral
<br>ecology. I would be
<br>extremely grateful if you could provide some more details on your
<br>observations.
<br>I would like to ask all coral listers as well - perhaps you saw
<br>something like Iain? Anything
<br>which could give a hint about the function of fluorescence? Or perhaps
I
<br>simply missed something
<br>in literature?
<br>best wishes,
<p>Mike Matz
<br>
<p>Iain Macdonald wrote:
<p>> During a recent field trip i noted the following along my transects.
<br>>
<br>> M. cavernosa recruits (i use the plural as this was seen three
<br>> different times), of only one polyp was noted at approx. 15-20m depth
<br>> to appear to the unaided eye as fluorescent orange. Close by (ie
<br>> 10cm away) 5 polyps were the typical olive green colour with this
<br>> "day glow" orange colour around its edges. Again a few cms away
<br>> larger colonies 20-25 polyps were only olive green. Is this typical
<br>> for recruits (i think not) or maybe as a result of some stress
<br>> (sediment) stimulus? I was startled to see such colour from this
type
<br>> of coral and would like to konw of any other observations.
<br>>
<br>> Cheers
<br>>
<br>> Iain Macd.
<br>>
<br>> Room E402 John Dalton Extension Building,
<br>> Department of Environmental and Geographical Science,
<br>> Manchester Metropolitian University,
<br>> Chester Street,
<br>> Manchester,
<br>> M1 5GD
<br>> Tel: 0161 247 6234
<br>> Fax: 0161 247 6318
<br> </blockquote>
</blockquote>
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