Fluorescence of corals commonly found in mesophotic reefs of the Red Sea.
Credit: Jörg Wiedenmann
 
Glowing corals that display a surprising 
array of colours have been discovered in the deep water reefs of the Red
 Sea by scientists from the University of Southampton, UK, Tel Aviv 
University and the Interuniversity Institute for Marine Sciences (IUI), 
Israel, together with an international team of researchers.
The researchers, whose findings have been published online today in research journal PLOS ONE, hope that some of the coral pigments could be developed into new imaging tools for medical applications.
The team studied corals at depths of more than 50 metres and found 
that many of them glow brightly with fluorescent colours, ranging from 
green over yellow to red. The encounter of such a rainbow of coral 
colours in deep waters was unexpected, since their shallow-water 
counterparts in the same reef contain only green fluorescent pigments.
Jörg Wiedenmann, Professor of Biological Oceanography and Head of the
 University of Southampton's Coral Reef Laboratory, explains: "These 
fluorescent pigments are proteins. When they are illuminated with blue 
or ultraviolet light, they give back light of longer wavelengths, such 
as reds or greens.
"Their optical properties potentially make them important tools for 
biomedical imaging applications, as their fluorescent glow can be used 
to highlight living cells or cellular structures of interest under the 
microscope. They could also be applied to track cancer cells or as tools
 to screen for new drugs."
Gal Eyal, PhD candidate at the IUI, says: "Corals from these 
so-called mesophotic reefs are less well studied since they are beyond 
the depth limits of standard Scuba diving techniques. Advances in 
technical diving have enabled us to explore coral communities from these
 deeper waters.
"Since only the blue parts of the sunlight penetrate to depths 
greater than 50 metres, we were not expecting to see any red coloration 
around. To our surprise, we found a number of corals showing an intense 
green or orange glow. This could only be due to the presence of 
fluorescent pigments."
Such pigments are often found in shallow water corals, where they can
 act as sunscreens for the corals and their symbiotic algae. Finding 
them in depths where corals are struggling to collect enough light to 
sustain the photosynthesis of their algal symbionts (a vital energy 
source for the corals) is therefore unexpected.
Dr Cecilia D'Angelo, Senior Research Fellow at Southampton, has 
studied corals commonly found in mesophotic depths in the experimental 
aquarium of the University's Coral Reef Laboratory: "In many shallow 
water corals, the production of the pigments is tightly controlled by 
the amount and colour of the incidental light. In the majority of our 
deep water species, the pigment production is essentially independent 
from the light exposure of the coral animals.
"We found, however, that some of the pigments of these corals require
 violet light to switch from their nascent green colour to the red hue 
of the mature pigment. This is a particularly interesting property to 
develop markers for advanced microscopic imaging applications."
The team now are now exploring which other biological functions these fluorescent pigments may fulfil.
Substantial parts of the research were conducted during the 
International Mesophotic Workshop 2014 held at the IUI in Eilat. Dr 
Yossi Loya, Professor of Zoology at Tel Aviv University and organiser of
 the workshop, concludes: "This study clearly shows the potential of 
interdisciplinary and international collaborations. We are delighted 
that the workshop has opened up such exiting new research avenues."
 Story Source:
The above post is reprinted from 
materials provided by 
University of Southampton. 
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