Researchers have identified how thyroxine, a human thyroid hormone, can positively influence the life-critical calcification in soft corals, and have developed a unique technique for injecting molecules into coral tissues.
"We understand a lot about hormones in vertebrates, but much less about hormones in invertebrate animals such as corals," says Clémence Forin, a PhD student at the Scientific Centre of Monaco. "We wanted to learn more about how they process hormones to find out how they are involved into the calcification process."
A major barrier to researching the role and regulation of hormones in corals has been the lack of established techniques. To address this, Ms Forin and her team set out to develop a novel injection method that would allow them to insert hormones into the corals and monitor how they affected the calcification process.
"The major benefits of this injection method are that we can accurately inject the same concentration of hormones each time, and that we can trace where it is going inside the organism," says Ms Forin. "We needed to make sure that all the hormones made it to the cells of interest and that soluble hormones wouldn't be lost in the surrounding seawater."
After screening many different widely available human hormones for pro-calcification effects, they identified a prime candidate in thyroxine. In humans and other vertebrates, thyroxine contributes to a variety of important functions such as growth and metabolism and has been associated with calcium transport.
"We found that thyroxine had a positive effect on the coral's calcification process," says Ms Forin. Using an ELISA (Enzyme-Linked Immunosorbent Assay), they were able to detect and quantify the hormone's processing and activity within the coral.
This finding raises interesting questions about the evolution of animal physiology. "If the coral is able to process and use the thyroxine, then it means that specific metabolic pathways have been conserved," says Ms Forin. "The big question now is how these corals utilise thyroxine in their natural habitat."
This research is being presented at the Society for Experimental Biology Annual Conference in Antwerp, Belgium on the 9th July 2025.
