The deep-water rainbow coral which has attracted researchers
Scientists hope the beautiful marine creatures discovered in the deep-water reefs of the Red Sea can be used to develop new drugs as well as tracking deadly cancer cells.
The value of the corals to medical science was realised when marine biologists dived to depths of 150 feet and compared their rainbow tones to shallow-water counterparts.
While the deep-water rainbow corals glow brightly with fluorescent colours, ranging from green and yellow to red, corals on the same reef but far nearer the surface have only green pigments.
The corals' potential for helping doctors fight cancer is explained by Professor of Biological Oceanography Jörg Wiedenmann of the University of Southampton, whose scientists made the discovery alongside colleagues from Tel Aviv University and also Israel's Interuniversity Institute for Marine Sciences (IUI).
Professor Wiedenmann, who is also head of the University of Southampton’s Coral Reef Laboratory, said: “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.”
Although corals look like plants, they are marine invertebrates, distantly related to sea anemones. They are made up of individual polyps and together they can create huge reef structures by secreting calcium.
Corals use pigments as sunscreen to protect themselves and their symbiotic algae in shallow tropical waters but the reason why the newly discovered deeper-water corals contain the rainbow pigments was unexpected. At such depth the algae, a vital energy source for corals, struggle to collect enough light to sustain photosynthesis.
News of the findings is published today in research journal PLOS ONE.
These fluorescent pigments ... could also be applied to track cancer cells or as tools to screen for new drugs
Gal Eyal, PhD candidate at the IUI, said: “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.”
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.
She said: “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.”