Rapid toxin sequestration impacts poison frog physiology

Poison frogs sequester their chemical defenses from their diet of leaf litter arthropods for defense against predation. Little is known about poison frog physiological adaptations that confer this unusual ability to bioaccumulate dietary alkaloids from the intestines to skin glands for storage. We conducted an alkaloid-feeding experiment with the Diablito poison frog (Oophaga sylvatica) to determine how quickly toxins are accumulated and how toxins impact frog physiology using quantitative proteomics. Diablito frogs were able to rapidly accumulate the alkaloid decahydroquinoline to the skin storage glands within four days of dietary exposure, with decahydroquinoline also detected in the intestines and liver. Alkaloid exposure impacted tissue physiology, with protein abundance shifting in the intestines, liver, and skin. Many proteins that increased in abundance with toxin accumulation are plasma glycoproteins, including components of the complement system and the toxin-binding protein saxiphilin. Other protein classes that change in abundance with toxin accumulation are membrane proteins involved in small molecule transport and metabolism, including ABC transporters, solute carrier proteins, and cytochrome P450s. Overall, this work shows that poison frogs can rapidly accumulate alkaloid toxins, which alter carrier protein abundance, initiate an immune response, and alter small molecule transport and metabolism dynamics across tissues. More broadly, this study suggests that acute changes in diet may quickly change the chemical arsenal and physiology of poison frogs, which may have important consequences in their defense against predation.