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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