Chitin, a chemical related to cellulose that makes up plant tissue or the cell wall of molluscs, is an essential building material of the exoskeleton of arthropods, including the bristles of marine worms, whose bristles allow them to move in aquatic environments. However, the mechanism by which one of nature's most abundant polysaccharides forms into bristles has remained unclear. A team of scientists from Vienna, Helsinki and Masaryk University Medical School has succeeded in describing it.
"A crucial role in this process is played by so-called chaetoblasts, cells with elongated surface structures known as microclusters. These microclusters contain a specific enzyme responsible for the synthesis of chitin, which is crucial for the construction of bristles," summarises Associate Professor Florian Raible, head of the research group at the Max Perutz Laboratories at the University of Vienna. He and his colleagues have revealed the geometric arrangement of the microclusters on the cell surface as well as the dynamics of bristle biosynthesis from chitin. They found that the regulated process of chitin deposition resembles 3D printing, where objects are formed layer by layer. And that it can be chemically manipulated to form specific shapes.
The international scientific team was assisted by Associate Professor Jaromír Gumulec from the Institute of Pathological Physiology at the Masaryk University Faculty of Medicine, who contributed to the imaging of thousands of samples using a special microscope. "Thanks to the microscope, which allows quantitative phase imaging, we were able to see structures that were not visible on other microscopes, and at the same time measure some biophysical properties of the material, such as its density," says Associate Professor Gumulec, confirming that Brno is a kind of "superpower of microscopy".
Although the study, currently published in Nature Communications, primarily describes very precisely the mechanism of bristle formation itself, the researchers believe that getting to the bottom of chitin synthesis offers translational potential, including in the production of polysaccharide materials, which are already being experimented with, for example, in the field of biodegradable packaging. These can be an alternative to plastic ones. "It is fascinating how precisely, with all those teeth, the worm is able to produce its bristles. The entire bristle, resembling a sabre, measuring a tenth of a millimetre, is 'printed' from a single cell that is ten times smaller," says Gumulec. "So far, we have only been able to do this very roughly, but who knows, maybe in the future we will be able to 'program' these cells to produce fine structures in the shapes we want."
