WOODHAMS, Douglas C.; RAMSEY, Jeremy P.; ROLLINS-SMITH, Louise A.*; Vanderbilt University Medical Center; Vanderbilt University Medical Center; Vanderbilt University Medical Center: Effects of cold temperature on antimicrobial peptide synthesis and release in northern leopard frogs, Rana pipiens

Amphibians inhabit both warm and cold temperature habitats. One important innate immune defense is antimicrobial peptides produced and stored in granular glands in the skin. Little is known about the effects of temperature on the ability frogs to release antimicrobial peptides or renew their stores of antimicrobial peptides following discharge. To examine this question, warm frogs (R. pipiens, 23°C) were placed at 4°C for 4 weeks and peptides were induced under cold conditions. The amount of peptides collected and the anti-chytrid activity of the peptide mixtures was equivalent to those of warm-temperature frogs. This demonstrates that peptide secretion capacity was not inhibited. MALDI-TOF MS showed a similar pattern of peptides present in the cold-adapted frogs as those present in the warm frogs. Next, 10 frogs were depleted of skin peptides by injection of 40 nmole/gbw NE. Some were kept at room temperature, and others were placed at 4°C. After 35 days, peptides were induced again. The warm frogs were able to recover and synthesize new peptides; however peptide synthesis in the cold-adapted frogs was reduced. Using MALDI-TOF MS, we also analyzed the profile of skin peptides released by leopard frogs as they emerged from natural hibernation (4-10�C) in the spring. We observed that the full set of peptides was present in hibernating frogs and was approximately equivalent to that of lab-acclimated frogs. Taken together our results suggest that cold conditions may temporarily interfere with new peptide synthesis after depletion and could influence the capacity of cold frogs to resist infection. [Support NSF IBN-0131184; DEB-0213851].