A vivid yellow worm dwelling in the scalding, mineral-rich fluids of Pacific hydrothermal vents has developed a remarkable survival trick: it fights poison with poison. Research shows that Paralvinella hessleri detoxifies its harsh surroundings by converting two potent toxins – arsenic and sulfide – into an intracellular mineral, orpiment (As₂S₃), dramatically reducing their bioavailability.
Published in PLOS Biology, the study marks the first demonstration of intracellular biomineralization of orpiment in a marine animal. Using an array of analytical techniques – including transmission electron microscopy, synchrotron-based X-ray absorption spectroscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy – the researchers confirmed the presence, composition, and structure of orpiment granules within the worm’s epidermal cells.
The vent worm can accumulate arsenic to levels exceeding 10,000 mg/kg dry weight – over 1 percent of its body mass – without succumbing to toxicity. Rather than relying solely on classical detoxification pathways (like binding arsenic to thiol groups or pumping it out of cells), P. hessleri sequesters arsenic within membrane-bound vesicles, where it reacts with environmental sulfide to form spherical orpiment nanoparticles, as revealed through subcellular elemental mapping.
“We were puzzled for a long time by the vibrant yellow granules,” the authors said in a press release. “It took us a combination of microscopy, spectroscopy, and Raman analysis to identify them as orpiment minerals – a surprising finding.”
Beyond its biochemical novelty, the discovery underscores how animals can co-opt geochemical processes to survive in extreme environments. The authors note that related invertebrates, such as deep-sea snails, may use a similar strategy – suggesting a broader ecological relevance for arsenic-sulfide biomineralization in vent communities.
Future studies will examine the genetic and regulatory machinery behind orpiment formation and assess whether similar mechanisms operate in other hydrothermal species. The researchers also propose that this model system could inspire biotechnological approaches for arsenic remediation or bioprecipitation.
“We hope that this ‘fighting poison with poison’ model will encourage scientists to rethink how marine invertebrates interact with and possibly harness toxic elements in their environment,” the authors conclude.
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