The surface of the coral is rough. Its hard skeleton is inhabited by polyps that extend their tentacles into the surrounding water to filter food. But how exactly does water flow across the coral’s surface, what eddies and currents develop, and what this means for the oxygen supply around the coral and its associated algae. ? An international research team around Soeren Ahmerkamp from the Max Planck Institute for Marine Microbiology in Bremen, Klaus Koren from Aarhus University in Denmark, and Lars Behrendt from Uppsala University and SciLifeLab in Sweden have developed a method allowing to study the flow and concentration of oxygen simultaneously at a very small scale. The coral can now be seen creating a flow using their cilia, thereby enhancing oxygen transport.
Watch corals breathe: A special camera records how oxygen-sensitive particles flow through the coral’s surface. This allowed the researchers to directly see the interaction between the flow field and oxygen concentration. Image credit: MPI f. Marine Microbiology / Soeren Ahmerkamp
The surface of the coral is rough. Its hard skeleton is inhabited by polyps that extend their tentacles into the surrounding water to filter food. But how exactly does water flow across the coral’s surface, what eddies and currents develop, and what this means for the oxygen supply around the coral and its associated algae. ? To date, there are no answers to these questions. Now, an international research team around Soeren Ahmerkamp from the Max Planck Institute for Marine Microbiology in Bremen, Klaus Koren from Aarhus University in Denmark, and Lars Behrendt from the Life Sciences Laboratory in Sweden have developed developed a method that allows the study of flow and oxygen concentrations simultaneously at a very small scale. The coral can now be seen creating a flow using their cilia, thereby enhancing oxygen transport.
Oxygen and life are closely related, from a single cell to an entire organism. To the extent of a few micrometers and within milliseconds, oxygen levels can change due to the flow or activity of organisms. Existing methods often measure oxygen concentration and flow separately, and as a result cannot detect much correlation between the two parameters. Ahmerkamp and his colleagues are now doing this in shock: They measure oxygen concentration and flow simultaneously with unmatched accuracy and speed. The researchers named their newly developed method sensPIV. PIV stands for “Particle Image Velocimetry”, an established method for measuring flow with particles. Now that “sense” is added, the particles sense their chemical surroundings.
The job is a technical challenge. In detail, the team created tiny particles less than 1 micrometer in size soaked in luminescent dye (for comparison: A human hair is about 100 micrometers in diameter). This dye glows more when there is less oxygen available. “It is especially important that the particles respond very quickly to changes in oxygen concentration. Co-author Farooq Moin Jalaluddin from the Max Planck Institute in Bremen, we also needed special cameras to accurately record the fluorescence. He adds, “With the sensPIV sensPIV method, we are able to resolve small-scale and fast fluid flows.”
Useful in medicine, biology and more
The flow of new particles growing on the coral’s surface can be seen. Image credit: Soeren Ahmerkamp / Max Planck Institute for Marine Microbiology
The possible applications of sensPIV are varied. Many organisms interact with oxygen, and so sensPIV can provide answers to open questions in the life sciences. For example, Ahmerkamp and his colleagues have used it, not only on coral, but also to examine in detail how oxygen flows through sand. Small-scale metabolic processes in microorganisms, animals and plants can also be studied. Many other applications are arising in microfluidicities, examining how fluids behave in the smallest spaces and in medicine.
The first idea for this method appeared several years ago. “But it was only through our great international team and our close collaboration that this idea has now become a versatile and functional app,” says Ahmerkamp. Now the team is excited about the upcoming applications of this method. “Particles are not difficult to produce once you know how,” says Klaus Koren. They are also thinking about further developing this method: “We want to make sensPIV able to take in substances other than oxygen. Klaus has been working on it,” adds Lars Behrendt.
Source: MPG
