Performance under pressure

A multi-institutional team that includes researchers from the University of Delaware, University of California San Diego and Monterey Bay Aquarium Research Institute (MBARI), among others, published a paper in Science on Thursday, June 27, that provides new insight on how deep-sea "comb jellies" called ctenophores adapt and survive at extreme pressures.

It turns out that part of the adaptation involves lipids, fatty chemical compounds found in the membrane of all living cells that perform essential functions, including storing energy, sending signals and controlling what passes through the cell membrane.

The work provides new knowledge about how marine organisms can adapt and survive in the ocean, now and potentially into the future. It also may inform what's known about the human body - in particular, how a specific lipid called plasmalogen found in nerve cells might work in our brains.

UD biophysicist Edward Lyman and doctoral students Sasiri Vargas-Urbano and Miguel Pedraza Joya are among the co-authors on the paper. Other co-authors include first-author Jacob Winnikoff, a researcher at MBARI and University of California, Santa Cruz and San Diego, now at Harvard University, Steven Haddock, an MBARI marine biologist, and the project principal investigator Itay Budin, an assistant professor of chemistry and biochemistry at UC San Diego. Additional collaborators include researchers from UCSD Health Sciences, University of California Santa Cruz, the National Institutes of Health and Cornell Center for High Energy X-ray Sciences.

Adapting under extreme pressure

Ctenophores are predators found at various depths in the ocean, where they help regulate the marine ecosystem by eating fish and shellfish larvae, while serving as a food source for other marine animals. If you go back in time, UD's Lyman said, the first thing that branches off from the rest of the animals is the ctenophores - a result just established last year by co-author Haddock.

"This means that you and I are more closely related to a jellyfish than a jellyfish is to a ctenophore," Lyman said.

The deep ocean, meanwhile, is characterized by low temperature and high pressure. Lyman explained that ctenophores are great for teasing apart this problem of how marine organisms adapt to extreme pressure environments because there are multiple ctenophore species that live at the surface, up to two and half miles deep in the ocean, and only at the surface in the Arctic, where the temperature is generally the same as in the deep sea.

"Studying ctenophores, you can compare those organisms in a way that's roughly controlled for temperature and now you can look at how the organism adapts only to changes in pressure," said Lyman, a UD professor of physics and astronomy with expertise using molecular dynamics simulations to characterize lipids.