Blue mussels, scientifically known as Mytilus edulis, spend their days being buffeted by harsh waves. The creatures manage to stay adhered to the rocks or to their fellow mussels. This is due to the highly effective underwater glue produced by them.
The mussels’ beards (which cooks remove before preparing them) are made up of byssal threads and are used to help keep the mussels tethered in place. At the end of each thread is a disc-shaped plaque that acts as an underwater glue. The unusual qualities of the glue and the byssal threads have interested people since ancient times, when the threads of certain species were woven into luxurious berets, purses, gloves, and stockings. More recently, scientists have developed underwater adhesives and surgical glues inspired by byssal thread chemistry. The identification of the mechanisms involved in creating the glue should advance work in this field. Image Credit: Tobias Priemel.
Achieving adhesion properties in the presence of water is a challenging task and scientists are drawing inspiration from these mussels to produce effective adhesives for application in wet conditions, for example, in surgical or dental conditions.
An international research team, led by McGill University has succeeded in revealing the cellular mechanism responsible for the underwater adhesive fabricated by the mussels.
The study was published in the journal Science.
The specific mechanism by which mussels produce their adhesive has been shrouded in mystery until now because everything occurs hidden from view inside the mussel foot.
Tobias Priemel, Study First Author and PhD Student, Harrington Laboratory, McGill University
Priemel has been working on this research for the past seven years, originally as an MSc student in Germany.
To understand the mechanisms involved we applied advanced spectroscopic and microscopic techniques and developed an experimental approach that combined several advanced and basic methodologies from across biochemistry, chemistry, and materials science.
Tobias Priemel, Study First Author and PhD Student, Harrington Laboratory, McGill University
Mussels Make Glue in 2 — 3 Minutes
After collating data at a subcellular level, the researchers uncovered that within the mussel foot, there exists micron-sized channels, that measure, just in diameter, about 1/10 to the full width of a human hair. This channel funnels the substances that come together to make the glue.
Condensed fluid proteins in minute sacs known as vesicles are secreted into the channel where they mix with metal ions like iron and vanadium that are taken up from seawater. The vesicles also store the metal ions and tend to slowly release them in a carefully timed process, curing (or hardening) the fluid protein into a solid glue.
The accumulation and usage of vanadium are certainly surprising as only a few other organisms are known to hyper accumulate vanadium. The researchers consider that hyperaccumulation serves a key part in hardening the glue and are proceeding with the research.
Mussels can make their underwater adhesive within 2-3 minutes by mixing metal ions with the fluid proteins. It’s a matter of bringing together the right ingredients, under the right conditions using the right timing. The more we understand about the process, the better engineers will later be able to adapt these concepts for manufacturing bio-inspired materials.
Matthew Harrington, Study Senior Author and Associate Professor, Department of Chemistry, McGill University
Journal Reference:
Priemel, T., et al. (2021) Microfluidic-like fabrication of metal ion–cured bioadhesives by mussels. Science. doi.org/10.1126/science.abi9702.