The quest for ctenophores: finding similarities in extremes

Recently, I had the privilege of meeting Jacob Winnikoff, a graduate research assistant at the Monterey Bay Aquarium Research Institute (MBARI). Touring the grounds at MBARI was exhilarating- aquariums gurgling, posters of marine invertebrates lining the walls, and rare specimens being stored in massive, dark freezers. Jacob works in the lab of senior scientist Dr. Steven Haddock, studying deep-sea gelatinous zooplankton. In collaboration with researchers in Washington and Florida, they are working on a research project cleverly named Diversity, Evolution and EcoPhysiology of Ctenophores (DEEPC). The DEEPC team strives to compare and investigate the complicated genetic history and adaptations of ctenophores.

Ctenophores are uniquely fascinating invertebrates; while staring directly at one, it can seem to disappear in an instant! Nonetheless, Jacob helps keep a keen eye on these animals while studying their biochemical adaptations to high pressure. Despite their abundance throughout the sea, ctenophores are ironically difficult to capture and process. Extracting DNA from these watery balls of barely organized tissue is challenging. Often, researchers will photograph an animal before collecting, freezing, and then cautiously sampling its delicate tissues. Jacob needed a lot of samples for a new study of ctenophore cell membranes, and the bigger specimens the better.

“Ah ha!”, I thought. The largest ctenophores that I have ever seen were up in the Arctic. Polar ctenophores may have similar physiology to their relatives living near the ocean floor. In these stressful environments of extreme temperature and/ or pressure, populations of ctenophores have evolved proteins and membranes specialized to cope. Fortuitously, I was about to return to the frigid, Arctic seas working on an expedition ship, so I offered to collect ctenophores while diving there.

Polar diving takes a lot of hard work, experience, patience, and a pinch of crazy. Typically the water temperature is below 0˚C , visibility is poor, and topside winds are strong. Despite conditions, I can never get enough of the sensational colors and wildlife found just below the sea’s surface. At just the right angle, even clear ctenophores burst with rainbows of color as light diffracts off their cilia.

Back in the laboratory onboard, I struggle to slurp the DNA-packed comb plates away from the remaining amorphous goop with a modified pipette. Even so, I was able to present Jacob with “probably the most comprehensive polar collection we’ve ever had!”

Experimentation is already underway as ctenophore DNA is inserted into bacteria, which then produce a larger supply of the enzymes of interest. Ongoing studies will focus on the physiological demands of ctenophores within diverse habitats experiencing contrasting ranges of pressure, temperature, oxygen, and food abundance. Jacob is working to pinpoint which parts of proteins most affect pressure or thermal tolerance, which could yield insights from bioengineering to ecological forecasting under climate change. Overall, DEEPC hopes to gain a better understanding of biochemical adaptations, and convergent evolution at environmental extremes.