Study shows lungless salamanders' skin expresses protein crucial for lung function

February 1, 2019 by Peter Reuell, Harvard University

For decades, scientists have assumed that the hundreds of species of salamanders that lack lungs actually "breathe" through their skin and the lining of the mouth, and Harvard researchers are providing the first concrete evidence for how they do it.

A new study, authored by James Hanken, Alexander Agassiz Professor of Zoology in the Museum of Comparative Zoology and curator of herpetology, Zachary Lewis, a postdoc working in Hanken's lab, and then-Harvard Extension School student Jorge Dorantes, shows that a gene that produces surfactant protein c—a key protein for lung function—is expressed in the skin and mouths of lungless salamanders, suggesting it also plays an important role for cutaneous respiration. The study is described in a paper published in the Proceedings of the Royal Society B.

"They are deploying the same kind of machinery that lunged salamanders use," Hanken said. "Generally, this had only been looked at from a morphological standpoint, so this is exciting because this is the first molecular-genetic correlation for this very interesting trait."

For years, scientists have pointed to salamander anatomy to support the idea that they breathe through the skin and mouth.

"What has been known for decades is that their blood supply is shunted from the heart to the skin," Hanken said. "There is a blood vessel that's not present in other animals—it would otherwise go to the lungs, but instead is goes to the skin.

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