Featured Research

from universities, journals, and other organizations

How marine mussels grip rocks: Iron atoms convey mussel fibers with a robust but stretchy covering

Date:
March 29, 2010
Source:
Max-Planck-Gesellschaft
Summary:
Researchers believe they have uncovered the basis how marine mussels use the byssus, a bundle of tough and extensible fibers, to fasten securely to wave-swept rocky coastlines. According to their findings, local accumulation of iron-mediated cross-links creates hard knobs within an extensible matrix containing much fewer of these molecular bridges. Such a design could be an interesting concept for developing novel abrasion-resistant, highly extensible coatings.

Mussels thrive in rocky seashore habitats, in spite of the enormous physical demands present there. This is in no small part due to the evolution of the byssus, which mussels employ to tether themselves to accessible surfaces.
Credit: iStockphoto/Simon Edwin

We may like to eat mussels steamed in white wine, but we also like to find mussels at the beach. Mostly they are burrowed into the ground or tethered to rocks. But if you look closer you will find a mollusc which has adapted to life and nutrition in a special and fascinating way. Mussels thrive in rocky seashore habitats, in spite of the enormous physical demands present there. This is in no small part due to the evolution of the byssus, which mussels employ to tether themselves to accessible surfaces.

Related Articles


The individual byssal threads that compose the byssus are stiff, but stretchy and are fashioned by the mussel in a process resembling injection molding. Byssal threads are depended upon for dissipating the energy of crashing waves and also for resisting abrasive damage from water-borne debris. To this end, threads are sheathed with a thin and knobby outer cuticle; a biological polymer, which exhibits epoxy-like hardness, while straining up to 100% without cracking.

Incredible hardness and extensibility

Matthew Harrington, a researcher who worked on the project and Humboldt fellow at the Max Planck Institute for Colloids and Interfaces explains the motivation for studying the byssus cuticle: "Protective coatings are important for prolonging the lifetime of materials and devices. However, considering that hardness and extensibility are seldom coupled in engineered polymers or composites, understanding how one protects a flexible substrate becomes quite important." Byssal cuticles have a knobby appearance due to inclusions of submicron-sized granular structures in an apparently continuous matrix. Submicron-sized tears that form in the matrix during stretching of the cuticle are believed to hinder the formation of larger cracks that could lead to material failure.

Central to understanding the peculiar mechanical behaviour of the cuticle are the high concentration of iron ions in the cuticle and the presence of an uncommon modification of the amino acid tyrosine known commonly as dopa. Dopa is found at high concentrations in the main cuticle component, mussel foot protein-1 (mfp-1). Dopa is distinguished from typical amino acids due to its impressive affinity for complexing with transition metal ions, particularly iron. As Admir Masic, a scientist at the Max Planck Institute for Colloids and Interfaces who worked on the project, explains, "when 2-3 dopa residues complex with a single iron ion, they create an incredibly stable complex that can be utilized to cross-link structural proteins." These metal-protein complexes have a high breaking force (nearly half that of covalent bonds), but unlike covalent bonds they are reversibly breakable, making them ideal for creating sacrificial cross-links.

Cuticle is stabilized by dopa-iron complexes

Using a technique known as in situ Raman spectroscopy to probe the chemical composition of the cuticle, the researchers provided the first direct evidence that the cuticle is a protein-based polymeric scaffold stabilized by dopa-iron complexes. Moreover, it was discovered that the distribution of dopa-iron complexes is clustered, with areas of high density coinciding with the granular inclusions and low density with the inter-granular matrix. These observations, coupled with previous mechanical observations suggest that the densely cross-linked granules function as hard inclusions and the less cross-linked matrix functions in a sacrificial manner, allowing bonds to break prior to catastrophic failure.

"Nature has evolved an elegant solution to a problem that engineers are still struggling with; namely, how to combine the properties of abrasion resistance and high extensibility in the same material," says Peter Fratzl, director of the biomaterials department at the Max Planck Institute for Colloids and Interfaces. Apparently, the cuticle achieves this through a careful tailoring of protein-metal chemistry and the submicron organization of cross-link density. "Conceivably, this same strategy could be applied in engineered polymers and composites."


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. Harrington et al. Iron-Clad Fibers: A Metal-Based Biological Strategy for Hard Flexible Coatings. Science, 2010; DOI: 10.1126/science.1181044

Cite This Page:

Max-Planck-Gesellschaft. "How marine mussels grip rocks: Iron atoms convey mussel fibers with a robust but stretchy covering." ScienceDaily. ScienceDaily, 29 March 2010. <www.sciencedaily.com/releases/2010/03/100304142234.htm>.
Max-Planck-Gesellschaft. (2010, March 29). How marine mussels grip rocks: Iron atoms convey mussel fibers with a robust but stretchy covering. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2010/03/100304142234.htm
Max-Planck-Gesellschaft. "How marine mussels grip rocks: Iron atoms convey mussel fibers with a robust but stretchy covering." ScienceDaily. www.sciencedaily.com/releases/2010/03/100304142234.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
3D Printed Cookies Just in Time for Christmas

3D Printed Cookies Just in Time for Christmas

Reuters - Innovations Video Online (Dec. 18, 2014) A tech company in Spain have combined technology with cuisine to develop the 'Foodini', a 3D printer designed to print the perfect cookie for Santa. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
First Etihad Superjumbo Flight in December

First Etihad Superjumbo Flight in December

AFP (Dec. 18, 2014) The first flight of Etihad Airways' long-awaited Airbus A380 superjumbo will take place later in December, the Abu Dhabi carrier said Thursday, also announcing its first Boeing 787 Dreamliner route. Duration: 01:09 Video provided by AFP
Powered by NewsLook.com
Ford Expands Air Bag Recall Nationwide

Ford Expands Air Bag Recall Nationwide

Newsy (Dec. 18, 2014) The automaker added 447,000 vehicles to its recall list, bringing the total to more than 502,000. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins