Study illustrates the protective role of fluorescence in neon-colored sea anemones

For the first time, a team of researchers from Stanford University and UC San Diego's Scripps Institution of Oceanography has found a direct genetic link between fluorescence and color in sea anemones.

In a detailed paper, the team explains the mysterious role of fluorescent proteins and color variation within a group of sea anemones living in the intertidal zones of the Pacific coast of North America. These sea anemones—belonging to the genus Anthopleura and commonly referred to as sunburst sea anemones—exhibit genetic color variation from vibrant neon-green to more subdued olive or gray-green hues.

The researchers found that the anemones' color variation, or polymorphism, is controlled by different versions of a fluorescent protein gene. The study also revealed that fluorescent proteins aren't just for display; They act as powerful antioxidants, protecting cells from oxidative damage, a very common stressor for cells.

Common stressors for sea anemones and other organisms in the intertidal zone include continuous exposure to sunlight, desiccation, and the presence of oxygen radicals generated by photosynthesis.

The findings were published In Proceedings of the National Academies of Sciences.

„The question we're essentially trying to answer with this study is, 'What makes these neon sea anemones so strikingly neon?' This led us to investigate the intriguing world of fluorescent proteins, which until now have remained a mystery,” said lead author Nat Clark, now a postdoctoral researcher at MIT and a Ph.D. student at Stanford University.

„This study sheds light on the multifunctional roles of fluorescent proteins in nature, balancing their spectral properties with important physiological roles.”

The group returned to the social platform NaturalistIt empowers citizen scientists to document biodiversity in their quest to locate the sometimes rare neon-green sea anemones.

From thousands of geotagged observations of Anthopleura sea anemones, the highest prevalence of neon color was found in northern California, with up to 10% of the population found in this hue, while their abundance dropped to less than 1% around San. Diego.

It all started with a remarkable observation

The inspiration for the research project began in 2008 when retired UC Santa Cruz professor John Pearce was exploring the tide pools of Monterey Bay and making deep observations. Coloring.

After this initial encounter, he returned to check on the glowing creature several times over the years, finding that it retained its remarkable coloration at any time of year and suggesting that this odd coloration was not an effect, despite variations in light conditions and tide conditions. environmental or external factors.

Pierce, an expert in the biology of sea anemones and other marine invertebrates, was curious to know more about the neon green anemone—why was it more luminous than others of the same species (is it the same species?), in the same place, on the same rock?

He enlisted the help of his wife, Vicki Pearce, a leading expert on anemones at Stanford University's Hopkins Marine Station, and other colleagues. John Pearce also served as a co-author on the study He is dead Before its release.

The fieldwork portion of the study began in 2016, when Clark and Pierce collected tentacle samples from neon and non-neon colored anemones in the intertidal zone near Hopkins Marine Station in Pacific Grove, California. Clark then used a suite of molecular tools to isolate and sequence the fluorescent protein.

Studying biofluorescence in the laboratory

The biofluorescence part of the research was carried out by Scripps Oceanography marine biologist Dimitri Dehaine and members of the Dehaine Laboratory, which specializes in investigating light production and light manipulation in living organisms. The researchers performed spectral analysis of the newly identified protein using a spectrophotometer, an instrument that examines light properties across a range of spectra.

In many species, color variations are considered phenotypic or observable traits, stemming from factors including different diets or adaptations to different environments. For example, species exposed to high levels of light often exhibit darker pigments. The researchers were surprised that the variation in color in these sea anemones was not considered a phenotypic trait, but rather a genotype associated with a specific fluorescent protein gene.

„This is the first time we've observed a fluorescent protein that dictates coloration in a sea anemone or marine invertebrate,” said Dehaine, who served as senior author of the paper. „The fact that color is strictly tied to a specific gene makes it even more intriguing and challenges the assumptions of most field observers.”

Protective role of fluorescent proteins

Researchers have demonstrated that the fluorescent proteins of anemones are strong antioxidants that can protect cells against oxidative stress. In humans, oxidative stress can trigger migraines, but consuming antioxidants like blueberries and dark chocolate can help manage and prevent this stress.

„Based on the data, we think the fluorescent protein helps the sea anemones cope with all the variable stressors they experience, and it allows them to 'take out the garbage' of the photosynthetic reaction. It doesn't hurt them,” Clark said. „This dual role of fluorescent proteins – as agents of both coloration and cellular defense – highlights the sophisticated ways in which marine organisms adapt to the challenges of their environments.”

According to the researchers, the study underscores the importance of citizen science and encouraging the public to continue sharing observations of neon-green sea anemones and other biodiversity through iNaturalist.

„Thanks to the dedication and efforts of citizen scientists, we can gain deeper insights into the population distribution of sea anemones, the gene pool of these organisms, and more,” said Dehaine. „Every observation, no matter how small or insignificant it may seem, plays an important role in expanding our knowledge and appreciation of the natural world.”