Aquatic caddisworm silk is solidified by environmental metal ions during the natural fiber-spinning process

What is it about?

Aquatic caddisflies (trichoptera) are a sister order to terrestrial silkworm moths (lepidoptera); they diverged about 200 million years ago from a silk spinning ancestor. Caddisfly larva use their silk to build composite protective structures-body armor-underwater. Silkworm silk has been studied extensively because of its commercial importance. Caddisworm silk, on the other hand, has received much less attention even though caddisworm silk offers new insights on natural underwater adhesion (the silk fibers are sticky underwater) and on the molecular adaptation of tough silk fibers to fully hydrated environments (terrestrial silks lose their strength in water). Such insights could inspire new materials, materials especially well suited to the fully hydrated internal tissue environment. We believe that the results will be of interest to the broad readership of the FASEB Journal. Part of the adaptation to underwater toughness is extensive phosphorylation of H-fibroin serine-rich motifs and the serial arrangement of highly organized metallophosphate nanodomains. This manuscript addresses when and where during silk fiber formation the metal ions (mostly calcium) is added to nascent fibers.

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