Marine mammals have lost a gene that provides protection from pesticide exposure

Through the long, twisting course of evolution, mammals have returned to the ocean on at least three separate occasions- once to become whales and dolphins (from an ancestor of the hippopotami), once to become manatees and dugongs (from an ancestor of the elephants), and once to become seals and sea lions (from an ancestor of bears and weasels). Each time they have apparently lost a specific gene known as Paraoxonase 1, or PON1, according to a new paper in Science co-authored by UW SRP's Clement Furlong and Judit Marsillach.

Two breaching orcas


The loss of this gene likely provided marine mammals with an adaptive advantage once they transitioned to a marine environment. Unfortunately, it also leaves them especially vulnerable to certain pesticides that arrive in marine environments in increasing concentrations through agricultural run-off. These pesticides, known as organophosphates, can cause paralysis and permanent brain damage.


Wynn Meyer, a Postdoctoral Associate in the lab of Nathan Clark at the University of Pittsburgh, first discovered the loss of PON1 as she was analyzing changes in gene function associated with the mammalian transition from a terrestrial to marine environment.


Clement Furlong, long an expert on PON1, was one of the first to show with rodent models that individuals who lack PON1 show greater susceptibility to the toxic effects of organophosphates and that injections with purified PON1 can restore protection. He notes that children don’t produce PON1 in high levels and, as a result, also show high vulnerability to organophosphate exposure.

Results published in the recent Science paper have received wide news coverage including articles in National Geographic, The New York Times, The Atlantic, Science News, and on the Expert Blog of the Natural Resources Defense Council.

After publication of this paper, several scientists have expressed interest in studying organophosphorus exposures in marine mammals such as manatees and dugongs. Marsillach developed a mass spectrometry-based assay for monitoring organophosphorus exposures as a Superfund trainee. Furlong and Marsillach are currently trying to obtain additional samples to monitor organophosphorus exposures using this assay.