[Coral-List] Coral fluorescence (Barbara Gratzer)

[Wiedenmann J.]

Hi Barbara, 

as Charlie pointed out, the key to the understanding of patterns of fluorescent and non-fluorescent GFP-like proteins is to appreciate that there is a functional diversity among them and corals might have them for different purposes in different parts of the colony, in different environments and probably also in different geographic regions. 

The purple and pink chromoproteins in acroporids and in many of corals are effective in photon removal and screening of zooxanthellae, hence they can contribute to the photoprotection of the symbionts. For instance, the reflection of the incident light from the skeleton in growth zones (tips and margins of a colony) results in higher internal light fluxes, which can cause a light-driven upregulation of the relevant pigment genes. During the colonisation of the growth zones by zooxanthellae, the CPs can provide additional "sunscreening" to reduce the increased light stress in this tissue. Once the zoox. population has established, the internal light fluxes drop and the pigment genes are down-regulated. For this reason, parts of coral colonies that regenerate mechanical damage or try to overgrow parasites/epibionts might become more colourful in these regions. This colour change is an indicator of some form of stress, but the response itself is a "healthy" reaction of the coral to the disturbance. 

Smith, E.G., D’Angelo, C., Salih, A., Wiedenmann, J., 2013. Screening by coral green fluorescent protein (GFP)-like chromoproteins supports a role in photoprotection of zooxanthellae. Coral Reefs 32, 463-474 

D'Angelo, C., Smith, E.G., Oswald, F., Burt, J., Tchernov, D., Wiedenmann, J., 2012. Locally accelerated growth is part of the innate immune response and repair mechanisms in reef-building corals as detected by green fluorescent protein (GFP)-like pigments. Coral Reefs 31, 1045-1056.

I hope this helps,

Joerg

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. Dr. Jörg Wiedenmann
National Oceanography Centre
University of Southampton, Waterfront Campus
European Way
Southampton, SO14 3ZH, U.K.
http://www.noc.soton.ac.uk/corals/
email: joerg.wiedenmann at noc.soton.ac.uk
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