Many plankton reach the surface from the cold, dark depths of the ocean, eventually drifting into the darkness again in an eternal rhythm. However, how single-celled phytoplankton, most of which don’t have appendages to help them swim, make this pilgrimage remains a mystery. In a paper published in the journal modern biologyResearchers describe a bioluminescent phytoplankton called Pyrocystis noctilucathe balloon expands to six times its original size (a few hundred microns).
Phytoplankton are on average 5%-10% heavier than seawater, which means they must find a way to overcome gravity if they want to stay on the surface to photosynthesize. Researchers found Noctiluca The cells behave more like small submarines and can control their density so they can choose where they want to reach the ocean surface.
On a research vessel off the coast of Hawaii, an author stumbles across a flower Noctiluca Surprisingly, they found two completely different sizes in their webs. The video helped the team see the massive expansion that occurred in the cells. To test what effect this rapid growth might have on plankton, the team used their novel “gravity machine.” By changing the water pressure and density within the gravity machine, the team was able to create a virtual reality environment that mimics the depth of the ocean. Using the machine, the team found that the swollen cells were less dense than the surrounding seawater, allowing them to escape the pull of gravity and float to the virtual surface.
Further research revealed that this expansion is a natural part of the plankton cell cycle. Once a single-celled plankton splits in two, an internal structure called a vacuole (a flexible tank) filters fresh water, causing the two new cells to greatly increase in size. The two daughter cells now swell with the lighter freshwater, sailing upward. “So, what happens normally? You produce a lot of protein, you have a lot of sunlight, you produce a lot of biomass until you get heavier and you sink. Then you do cells in deeper water. divide and use expansion to return to the size of the parent body,” Manu Prakash, a marine biologist and bioengineer at Stanford University, said in a press release.
The entire cell cycle takes approximately 7 days, coinciding with the plankton’s vertical pursuit of light and nutrients. “I think this is the first time we have clear evidence that the cell cycle, a fundamental mechanism that controls cells and cell division, may be controlled by ecological parameters,” Dr. Prakash said in the press release.
Published – October 19, 2024 at 9:20 pm (IST)