Byssus

Fine linen, Byssos (Greek: βύσσος ) or byssus is a name for the secretion of the Fußdrüsen different types of shells. The individual secretions of several glands form mainly phenolic proteids, which are combined together to prison threads and harden in the bottom of the shells. While many mussel species produce only as young mussels linen, this secretion may persist in others life. Known examples of mussels with byssus threads are the mussels, attach themselves to the byssus threads of structures of the surf zone and this also can be released again in poor environmental conditions, and the fig shells, spin the entire networks from Byssosfäden, to fix a foreign body.

Byssus of the mussel in antiquity

Since ancient times, the fibers of living in the Mediterranean noble pen shell ( Pinna nobilis L. ) are obtained. The fabrics made ​​from these fibers are called linen. However, the majority of the ancient occurrences of the word Byssos thinks precious, precious or fine linen, fine cotton. The New Testament occurrences of the word Byssos (or its derivatives ) in Lk 16,19 EU, EU Rev 18, Rev 12:16 and 19 EU, 8:14 My fine linen. The fiber is shiny gold, very thin and extremely strong and durable, is comparable with modern nylon threads. The mussel is by far the largest of the Mediterranean mussel. It can be up to one meter long. Today, the mussel is protected, almost extinct craft.

In ancient times, the woven of fine linen or wool fabric pen shell, called byssus, or sea silk, a very precious textile material. It is often argued, linen was " many times finer than silk ," however, the Byssusfasern a cross section of about 10-50 microns, scoured silk has a cross section of 7-20 microns, only tussah silk (wild silk) with a diameter of 20 - 40 microns is much coarser in comparison. Because of its durability and the elaborate extraction linen is highly sought after and valuable. Textiles from sea silk were very popular, especially in the Middle Ages under high ecclesiastical dignitaries and nobility.

The commercial production of Byssustextilien in Sardinia ended in the 40s of the 20th century. Byssus is now processed only on the Sardinian island of S. Antioco where there is also a Byssos Museum is located.

Known substances from history

One of the most well-known products, which is probably from Byssos, is the veil of Manoppello. On it is seen generally considered a reflection of the face of Jesus Christ. In what way the image has been made ​​on the veil remains unclear, because the church does not agree to an investigation. It is assumed that this cloth was woven from byssus threads and a painting of this substance would not readily possible.

Composition

Byssus produced by several species of shellfish, such as Pinna sp., Mytilus sp., Bathymodiolus thermophilus, Guekensia demissa, Modiolus modiolus and Dreissena polymorpha ( zebra mussel ).

Byssus threads have compared to hair a smooth fiber surface without scales, the fiber cross-section is elliptical and can be well distinguished from silk fibers. The diameter of the fibers is between 10 and 45 microns, so that the finer fibers including, after sorting, are among the finest animal natural fibers. Byssus threads are little tear especially in the dry state, because under the animal natural fibers linen is in its tensile strength of spider silk, silk and animal hair exceeded (eg Araneus diadematus of ). The tensile strength is 75 megapascals for the proximal portion of the fiber 35 megapascals and for the distal part. The proximal part of the byssus can be stretched to three times its length, and thus has a comparatively high ductility, which is exceeded under the animal only natural fibers of spider silk. The tear firmer, distal portion of the fiber can be stretched to twice its length.

The byssus threads of Mytilus sp Salzwassermuschelart. consist of a fiber core of three collagen -like proteins Precol -NG, Precol -D and Precol -P (of English. Precollagen ) and a fiber cladding from the proteins Mfp 1-6 (of English. Mussel foot protein). Mfp -1 coated as fiber cladding (Latin cuticle ) Precol the proteins of the fiber core and the fiber reduces corrosion in seawater. Mfp -3 and Mfp -5 are about stored and mainly responsible for the adhesion. Among the three proteins of the fiber core is Precol -NG ( ENGL. Non- gradient, evenly distributed ') distributed over the entire fiber Precol D occurs in the distal area and Precol P occurs in the proximal region. The medium brown color is caused by the deposition of pheomelanin. The MFP 1 is cross-linked non-covalently via calcium ions and iron ions in the dihydroxyphenyl -L- alanines, which increases the strength. The dihydroxyphenyl -L- alanine in the Mfp - 1 is formed from tyrosine by posttranslational modification. In the fiber cladding consisting of Mfp -1, there is glomerular areas with particularly strong cross-linked and firmer Mfp -1, which are embedded in a layer of less cross-linked Mfp -1. The dihydroxyphenyl -L -alanine, also contributes to an increased absorption of light and thus a UV protecting Byssusproteine ​​.

Despite the lower flow velocities in the habitat under the mentioned species of mussels have the byssus threads of the freshwater mussel Dreissena polymorpha the highest tensile strength of the fiber over the entire length, presumably because their Byssusfasern no collagen-like proteins contains. The Byssusproteine ​​of Dreissena sp. are also crosslinked by dihydroxyphenyl -L- alanine, and have a typical electron-dense contact surface. The salt water mussels, there are significant strength differences between proximal and distal regions of the byssus threads, the more distant ( distal, Precol -D -containing ) are parts, taken individually, stronger than those of the freshwater mussel Dreissena sp.