Response to Comment on "High Abrasion Resistance with Sparse Mineralization: Copper Biomineral in Worm Jaws"

Distribution and Role of Trace Transition Metals in Glycera Worm Jaws Studied with Synchrotron Microbeam Techniques

“…Given the His-rich composition of Glycera jaws, here the protein matrix may be involved in Zn binding. Since in contrast to Nereis jaw, Cl was not found in the matrix of the Glycera jaw, a zinc-insulin-type coordination can be excluded; as Cys was not detectable in the Glycera jaw, a zinc-finger motif can be excluded as well. Still, the variety of remaining possibilities of Zn−His coordination is considerable .…”

“…Energydispersive X-ray analysis experiments on transmission electron microscopy (TEM) sections from the jaw tip have shown that also the matrix between adjacent atacamitereinforced fibers contains some Cu. 10 Other researchers have suggested that there may be more Cu compounds in the jaw, different from atacamite, and perhaps in even greater abundance. 19 XAS is a very sensitive tool for the identification of chemical compounds and was used here to screen the jaw for any copper compounds different from atacamite.…”

“…Zinc is not the only metal dispersed in the jaw matrix: traces of Cu are also found throughout the jaw in addition to the Cu-based mineral in the jaw tip (Figure b). Energy-dispersive X-ray analysis experiments on transmission electron microscopy (TEM) sections from the jaw tip have shown that also the matrix between adjacent atacamite-reinforced fibers contains some Cu . Other researchers have suggested that there may be more Cu compounds in the jaw, different from atacamite, and perhaps in even greater abundance …”

“…5 Notably, the amino acid composition resembles that found in the jaws of Nereis, a related worm species that uses zinc rather than copper to harden its mandibles, however, in the nonmineralized form. 6 In a previous study, it was found that Glycera jaws contain more copper than can be attributed to the atacamite mineral (calculated from the Cu/Cl ratio in the jaw as compared to that in the mineral), 10 but its nature was not further explored. Here we use a combination of several state-of-the-art synchrotron microfocus techniques such as X-ray fluorescence imaging (XFI), X-ray absorption spectroscopy (XAS), anomalous small-angle X-ray scattering (aSAXS), and microdiffraction (micro-XRD) to study the distribution and role of unmineralized copper and other inorganic trace components such as zinc and iron in the Glycera jaw.…”

Biomechanics of substrate boring by fig wasps

“…Similarly, the presence of transition metals in larvae mandibles of Stegobium paniceum and Gibbium aequinoctiale species of beetles aids in boring into hard seeds as oppposed to others without metals, which are incapable of seed boring (Morgan et al, 2003). The presence of transition metals in insect cuticle and mandible is hypothesized to increase material hardness to permit cutting through hard substrates with minimal wear (Schofield et al, 2002;Schofield et al, 2003;Lichtenegger, 2003;Quicke et al, 1998;Hillerton and Vincent, 1982;Fawke et al, 1997). Although repeated use of the ovipositor when boring through stiff substrates is expected to cause increased wear in the interacting surfaces, the ovipositors of wood-boring wasps show little evidence of wear and tear of their cutting parts .…”