How the Purple and Pink Sunscreens of Reef Corals Work

Jan. 23, 2013 — New research by the University of Southampton has found a mechanism as to how corals use their pink and purple hues as sunscreen to protect them against harmful sunlight.

Pocillopora damicornis coral from the Red Sea expressing a pink photoprotective chromoprotein. (Credit: Image courtesy of University of Southampton)
 

Many reef corals need light to survive, as they benefit from sugars and lipids that are produced by their light-dependent symbiotic algae. However, in the shallow water of coral reefs, light levels are often higher than required by the corals, so paradoxically, the vital sunlight can become harmful for the algae and their hosts.

Apart from temperature, light stress is a major driver of coral bleaching — the loss of the symbiotic algae that represents a threat to coral reef survival.

Working in the Great Barrier Reef and under tightly controlled conditions in the Coral Reef Laboratory of the University of Southampton, the team of researchers produced experimental evidence that the pink and purple chromoproteins can act as sunscreens for the symbiotic algae by removing parts of the light that might become otherwise harmful.

Dr Jörg Wiedenmann, Senior Lecturer of Biological Oceanography and Head of the University’s Coral Reef Laboratory, who led the study says: “The beautiful pink and purple hues that are produced by the coral host are often evoked by chromoproteins; pigments that are biochemically related to the green fluorescent protein (GFP) of the jellyfish Aequorea victoria. In contrast to their green glowing counterpart, the chromoproteins take up substantial amounts of light, but they don’t re-emit light.

“GFP-like proteins were suggested to contribute to the protection of corals and their symbionts from excess sunlight. This hypothesis has been controversially discussed as the mechanism as to how these pigments function remained unclear. At least for the chromoproteins we know now that they have indeed the capacity to fulfill this function.” The researchers also proposed an explanation for the mysterious phenomenon that some corals accumulate exceptionally high amounts of chromoproteins in growing areas, such as branch tips or in the region of healing wounds.

Dr Wiedenmann, who is based at the National Oceanography Centre, Southampton, explains: “These growing areas contain essentially no symbiotic algae, so much of the light is reflected by the white coral skeleton instead of being used by the algae. The resulting increased light intensities in the new parts of the coral represent a potential danger for the algal cells that need to colonise these areas. Hence, it seems that the corals use a clever trick to help their symbionts. The higher light intensity switches on the genes that are responsible for the production of the sunscreening chromoproteins.

“Our results suggest that the screening effect of the chromoproteins could help the algae to enter the new tissue. Once the symbiont population is fully established, the light levels in the tissue decrease as the algae use most of the light for photosynthesis. As a consequence, the genes of the chromoproteins are switched off again which allows the coral to save the energy required for their production.”

The research contributes to a better understanding of the coral’s response to environmental stress. Knowledge of the stress resilience of corals is an important requirement to help predictions of the fate of coral reefs that are exposed to climate change and various forms of anthropogenic disturbance.

The paper is published in the latest edition of the journalCoral Reefs.

 

Story Source:

The above story is reprinted from materials provided byUniversity of Southampton.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. E. G. Smith, C. D’Angelo, A. Salih, J. Wiedenmann.Screening by coral green fluorescent protein (GFP)-like chromoproteins supports a role in photoprotection of zooxanthellaeCoral Reefs, 2013; DOI: 10.1007/s00338-012-0994-9
University of Southampton (2013, January 23). How the purple and pink sunscreens of reef corals work. ScienceDaily. Retrieved January 28, 2013, from http://www.sciencedaily.com/releases/2013/01/130123094129.htm
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Dermatologists’ Tips to Reduce the Signs of Aging

ScienceDaily (Aug. 14, 2012) — Getting better results from your anti-aging products can be as easy as following simple tips from dermatologists.

“People often think that the more expensive a product is, the more effective it will be,” said board-certified dermatologist Susan C. Taylor, MD, FAAD, founding director of the Skin of Color Center at St. Luke’s and Roosevelt Hospitals in New York City. “That’s not always the case. People need to shop smart since there are some very effective, affordable products in the skin care aisles of their local stores.”

To get the most from age-fighting products, Dr. Taylor recommends people also follow these tips:

1. Wear sunscreen every day since the sun’s rays can accelerate signs of aging. Use a sunscreen or facial moisturizer that offers broad-spectrum protection and has an SPF of at least 30. Be sure to apply sunscreen to all skin that is not covered by clothing.

2. Do not tan. Getting a tan from the sun or a tanning bed exposes you to harmful UV rays that can accelerate aging, causing wrinkles, age spots, a blotchy complexion and even skin cancer.

3. Moisturize. Moisturizing traps water in the skin, which can help reduce the appearance of some fine lines and make your complexion look brighter and younger.

4. Test products, even those labeled “hypoallergenic.” To test, dab a small amount of the product on your inner forearm twice a day for four to five days. If you do not have a reaction, it is likely safe for you to apply to your face.

5. Use the product as directed. Active ingredients can do more harm than good when too much is used. Applying more than directed can cause clogged pores, a blotchy complexion, or other unwanted effects.

6. Stop using products that sting or burn unless prescribed by a dermatologist. Irritating the skin makes signs of aging more noticeable.

o Some products prescribed by a dermatologist may cause stinging or burning. When under a dermatologist’s care, this can be safe and effective.

7. Limit the number of products. Using too many products on your skin, especially more than one anti-aging product, tends to irritate the skin. This often makes signs of aging more noticeable.

“It’s very important that people allow time for the product to work. While a moisturizer can immediately plump up fine lines, most products take at least six weeks to work and sometimes it can take three months,” said Dr. Taylor. “See a dermatologist if after following these tips you still do not see the expected results,” said Dr. Taylor.

 


Story Source:

The above story is reprinted from materials provided byAmerican Academy of Dermatology (AAD), via Newswise.


Citation:

American Academy of Dermatology (AAD) (2012, August 14). Dermatologists’ tips to reduce the signs of aging. ScienceDaily. Retrieved August 16, 2012, from http://www.sciencedaily.com/releases/2012/08/120814085330.htm