“The newly described fluorescent molecules emit a surprising amount of light, providing about 18% as much visible light as a full Moon — enough for a related species of frog to see by. Almost nothing is known about the polka dot tree frog’s visual system or photoreceptors, so Taboada plans to study these to determine whether the frogs can see their own fluorescence.”
Many species of coral produce fluorescent pigments that light up in a dazzling display of neon colours when exposed to UV light.
Fluorescence is the phenomenon whereby a substance absorbs electromagnetic radiation (such as light) and emits it at a lower energy level. In this case, the corals’ fluorescent proteins absorb invisible high energy UV light and emits visible light, which has longer wavelengths and lower energy.
Scientists have hypothesised several reasons for fluorescence in corals.
Corals form symbiotic relationships with algae called zooxanthellae, which they house in their polyps. The algae photosynthesise and provide nutrients for the coral. However, the algae are not able to process UV light. Through fluorescence, the corals may be able to turn the UV light into wavelengths that are useful to the algae for photosynthesis, especially in darker environments.
It has also been suggested that the fluorescence provides protection against UV rays, notably in shallow water. UV rays are mutagenic and are capable of damaging cells in both the coral and symbiotic algae. Fluorescence may be a means to convert UV light into harmless lower energy wavelengths in order to protect both the coral and algal cells.
Studies have shown that corals with higher concentrations of fluorescent proteins are more resistant to bleaching.
The green fluorescent protein (GFP) is a protein that exhibits bright green fluorescence when exposed to light in the blue to ultraviolet range. Although many other marine organisms have similar green fluorescent proteins, GFP traditionally refers to the protein first isolated from the jellyfish Aequorea victoria. Jellyfish-derived GFP has been engineered to produce a vast number of useful blue, cyan and yellow mutants, and fluorescent proteins from a variety of other species have also been identified, resulting in further expansion of the available color palette into the orange, red and far-red spectral regions. Together, these highly useful genetically encoded probes are broadly referred to as fluorescent proteins The FP gene can be introduced into organisms and maintained in their genome through breeding, injection with a viral vector, or cell transformation. Green fluorescent protein has transformed biomedical research. Using a gene that carries instructions to make GFP, scientists can attach harmless glow-in-the-dark tags to selected proteins, either in cells in lab dishes or inside living creatures, to track their activity. It’s like shining a flashlight on the inner workings of cells. These days, scientists can track how cancer cells spread, how HIV infections progress and even which male ends up fertilizing a female fruit fly’s egg. These and many other studies that offer insight into human health all benefit from a green, glowing protein first found in a sea creature.