Spider silks are among the toughest known materials and thus provide models for renewable, biodegradable, and sustainable biopolymers. However, the entirety of their diversity still remains elusive, and silks that exceed the performance limits of industrial fibers are constantly being found. We obtained transcriptome assemblies from 1098 species of spiders to comprehensively catalog silk gene sequences and measured the mechanical, thermal, structural, and hydration properties of the dragline silks of 446 species. The combination of these silk protein genotype-phenotype data revealed essential contributions of multicomponent structures with major ampullate spidroin 1 to 3 paralogs in high-performance dragline silks and numerous amino acid motifs contributing to each of the measured properties. We hope that our global sampling, comprehensive testing, integrated analysis, and open data will provide a solid starting point for future biomaterial designs.
The tiny spider makes
dragline silk fibers with unbeatable toughness,
all under the most innocuous conditions. Scientists have persistently
tried to emulate its natural silk spinning process using recombinant
proteins with a view toward creating a new wave of smart materials,
yet most efforts have fallen short of attaining the native fiber’s
excellent mechanical properties. One reason for these shortcomings
may be that artificial spider silk systems tend to be overly simplified
and may not sufficiently take into account the true complexity of
the underlying protein sequences and of the multidimensional aspects
of the natural self-assembly process that give rise to the hierarchically
structured fibers. Here, we discuss recent findings regarding the
material constituents of spider dragline silk, including novel spidroin
subtypes, nonspidroin proteins, and possible involvement of post-translational
modifications, which together suggest a complexity that transcends
the two-component MaSp1/MaSp2 system. We subsequently consider insights
into the spidroin domain functions, structures, and overall mechanisms
for the rapid transition from disordered soluble protein into a highly
organized fiber, including the possibility of viewing spider silk
self-assembly through a framework relevant to biomolecular condensates.
Finally, we consider the concept of “biomimetics” as
it applies to artificial spider silk production with a focus on key
practical aspects of design and evaluation that may hopefully inform
efforts to more closely reproduce the remarkable structure and function
of the native silk fiber using artificial methods.
DNP solid state NMR spectroscopy allows non-targeted analysis of wild spider silk in unprecedented detail at natural abundance, revealing hitherto unreported features across several species.
Spider major ampullate (MA) silk, with its combination of strength and extensibility, outperforms any synthetic equivalents. There is thus much interest in understanding its underlying materiome. While the expression of the different silk proteins (spidroins) appears an integral component of silk performance, our understanding of the nature of the relationship between the spidroins, their constituent amino acids and MA silk mechanics is ambiguous. To provide clarity on these relationships across spider species, we performed a meta-analysis using phylogenetic comparative methods. These showed that glycine and proline, both of which are indicators of differential spidroin expression, had effects on MA silk mechanics across the phylogeny. We also found serine to correlate with silk mechanics, probably via its presence within the carboxyl and amino-terminal domains of the spidroins. From our analyses, we concluded that the spidroin expression shifts across the phylogeny from predominantly MaSp1 in the MA silks of ancestral spiders to predominantly MaSp2 in the more derived spiders' silks. This trend was accompanied by an enhanced ultimate strain and decreased Young's modulus in the silks. Our meta-analysis enabled us to decipher between real and apparent influences on MA silk properties, providing significant insights into spider silk and web coevolution and enhancing our capacity to create spider silk-like materials.
During the 1981–82 austral summer a Joint Services Expedition to South Georgia recorded meteorological observations at Royal Bay, near to the site of the German station of the First International Polar Year in 1882–83. Comparisons between the two sets of observations emphasize the storminess of the climate and indicate slightly higher temperatures in 1981–82. Weather conditions at Royal Bay in 1981–82 were more comparable to those at King Edward Point (Grytviken), the main meteorological station on the island, than in the central mountains of the Salvesen Range.
Silk is a unique fiber, having a strength and toughness that exceeds other natural fibers. While inroads have been made in our understanding of silkworm silk structure and function, few...
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