1
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Piorkowski D, Liao CP, Blackledge TA, Tso IM. Size-related increase in inducible mechanical variability of major ampullate silk in a huntsman spider (Araneae: Sparassidae). Naturwissenschaften 2021; 108:22. [PMID: 33945014 DOI: 10.1007/s00114-021-01724-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 02/10/2021] [Accepted: 03/02/2021] [Indexed: 10/21/2022]
Abstract
Most spiders use major ampullate silk (MAS) to perform many functions across their lifetimes, including prey capture, vibratory signal detection, and safety/dragline. To accommodate their various needs, adult spiders can use inducible variability to tailor MAS with specific mechanical properties. However, it is currently unknown whether this inducible mechanical variability develops gradually or remains consistent across spider size. Supercontraction -a process by which "native-state" silk fibers axially shrink when exposed to water or high humidity-can be used to reveal the extent of inducible variability in MAS. Supercontraction removes some processing effects that occur during the spinning of the solid fiber from its liquid precursor by allowing a native-state MAS fiber to return to a low energy "ground-state". Here, we examined the relative extent of inducible variability of MAS across spider size by assessing supercontraction properties and the difference between ground- and native-state MAS tensile properties using silk from the huntsman spider Heteropoda venatoria (Sparassidae). Stiffness of forcibly pulled native-state silk increased by 200% with spider size. After exposure to 90% RH and subsequent supercontraction, axial shrinkage of native-state silk fibers increased by 15% in larger spiders. Supercontracted, ground-state fibers demonstrated a 200% increase in extensibility across spider size. Our results indicate a gradual increase in inducible variability of MAS mechanical properties across spider size potentially caused by shifts in internal processing or chemical composition. These findings imply both development of inducible variability and changes in use of MAS as a safety line or aiding jumps across a spider's lifetime.
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Affiliation(s)
- Dakota Piorkowski
- Department of Life Science, Tunghai University, Taichung, 407224, Taiwan
| | - Chen-Pan Liao
- Department of Life Science, Tunghai University, Taichung, 407224, Taiwan.,Department of Biology, National Museum of Natural Science, Taichung, 404023, Taiwan
| | - Todd A Blackledge
- Department of Biology, Integrated Bioscience Program, The University of Akron, Akron, OH, 44325, USA
| | - I-Min Tso
- Department of Life Science, Tunghai University, Taichung, 407224, Taiwan. .,Center for Tropical Ecology and Biodiversity, Tunghai University, Taichung, 407224, Taiwan.
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2
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Wang Z, Cang Y, Kremer F, Thomas EL, Fytas G. Determination of the Complete Elasticity of Nephila pilipes Spider Silk. Biomacromolecules 2020; 21:1179-1185. [PMID: 31935074 PMCID: PMC7307882 DOI: 10.1021/acs.biomac.9b01607] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
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Spider silks are
remarkable materials designed by nature to have
extraordinary elasticity. Their elasticity, however, remains poorly
understood, as typical stress–strain experiments only allow
access to the axial Young’s modulus. In this work, micro-Brillouin
light spectroscopy (micro-BLS), a noncontact, nondestructive technique,
is utilized to probe the direction-dependent phonon propagation in
the Nephila pilipes spider silk and
hence solve its full elasticity. To the best of our knowledge, this
is the first demonstration on the determination of the anisotropic
Young’s moduli, shear moduli, and Poisson’s ratios of
a single spider fiber. The axial and lateral Young’s moduli
are found to be 20.9 ± 0.8 and 9.2 ± 0.3 GPa, respectively,
and the anisotropy of the Young’s moduli further increases
upon stretching. In contrast, the shear moduli and Poisson’s
ratios exhibit very weak anisotropy and are robust to stretching.
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Affiliation(s)
- Zuyuan Wang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yu Cang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Friedrich Kremer
- Institute of Experimental Physics I, University of Leipzig, Linnéstr. 5, 04103 Leipzig, Germany
| | - Edwin L Thomas
- Department of Materials Science and Nano-Engineering, Rice University, Houston, Texas 77030, United States
| | - George Fytas
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.,Institute of Electronic Structure and Laser, F.O.R.T.H, 70013 Heraklion, Greece
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3
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Small size does not confer male agility advantages in a sexually-size dimorphic spider. PLoS One 2019; 14:e0216036. [PMID: 31091246 PMCID: PMC6519806 DOI: 10.1371/journal.pone.0216036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 04/12/2019] [Indexed: 11/19/2022] Open
Abstract
Selection pressures leading to extreme, female-biased sexual size dimorphism (SSD) in spiders continue to be debated. It has been proposed that males of sexually size dimorphic spiders could be small because gravity constrains adult agility (locomotor abilities). Accordingly, small males should achieve higher vertical climbing speeds and should be more prone to bridge. The curvilinear model of the gravity hypothesis predicts a negative relationship between vertical climbing speed and male body size only over a threshold of 7.6 mm, 42.5 mg. Because males of most species with extreme SSD fall well below this threshold, the relationship between male size and agility at this scale remains vague. Here, we tested three hypotheses on how male size, mass and age (after maturation) relate to vertical climbing and bridging ability in Nephilingis cruentata, a highly sexually dimorphic orb-weaver with males well below the size threshold. We placed males of different sizes and adult ages in a vertical platform and recorded their climbing speeds. Contrary to the original study testing male bridging ability as binary variable, we measured the duration of the crossing of the bridging thread, as well as its sagging distance. Male body size and mass positively related to the vertical climbing speed and to the distance of the sagging thread during bridging, but had no influence on the bridging duration. The detected positive correlation between male size/mass and vertical climbing speed goes against our first prediction, that small males would have vertical climbing advantage in Nephilingis cruentata, but agrees with the curvilinear model. Against our second prediction, small males were not faster during bridging. Finally, in agreement with our third prediction, threads sagged more in heavier males. These results suggest that small male size confers no agility advantages in Nephilingis cruentata.
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4
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Blamires SJ, Nobbs M, Martens PJ, Tso IM, Chuang WT, Chang CK, Sheu HS. Multiscale mechanisms of nutritionally induced property variation in spider silks. PLoS One 2018; 13:e0192005. [PMID: 29390013 PMCID: PMC5794138 DOI: 10.1371/journal.pone.0192005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 01/14/2018] [Indexed: 12/14/2022] Open
Abstract
Variability in spider major ampullate (MA) silk properties at different scales has proven difficult to determine and remains an obstacle to the development of synthetic fibers mimicking MA silk performance. A multitude of techniques may be used to measure multiscale aspects of silk properties. Here we fed five species of Araneoid spider solutions that either contained protein or were protein deprived and performed silk tensile tests, small and wide-angle X-ray scattering (SAXS/WAXS), amino acid composition analyses, and silk gene expression analyses, to resolve persistent questions about how nutrient deprivation induces variations in MA silk mechanical properties across scales. Our analyses found that the properties of each spider's silk varied differently in response to variations in their protein intake. We found changes in the crystalline and non-crystalline nanostructures to play specific roles in inducing the property variations we found. Across treatment MaSp expression patterns differed in each of the five species. We found that in most species MaSp expression and amino acid composition variations did not conform with our predictions based on a traditional MaSp expression model. In general, changes to the silk's alanine and proline compositions influenced the alignment of the proteins within the silk's amorphous region, which influenced silk extensibility and toughness. Variations in structural alignment in the crystalline and non-crystalline regions influenced ultimate strength independent of genetic expression. Our study provides the deepest insights thus far into the mechanisms of how MA silk properties vary from gene expression to nanostructure formations to fiber mechanics. Such knowledge is imperative for promoting the production of synthetic silk fibers.
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Affiliation(s)
- Sean J. Blamires
- Evolution & Ecology Research Centre, School of Biological, Earth & Environmental Sciences D26, The University of New South Wales, Sydney, Australia
| | - Madeleine Nobbs
- Evolution & Ecology Research Centre, School of Biological, Earth & Environmental Sciences D26, The University of New South Wales, Sydney, Australia
| | - Penny J. Martens
- Graduate School of Biomedical Engineering, Samuels Building F25, The University of New South Wales, Sydney, Australia
| | - I-Min Tso
- Department of Life Science, Tunghai University, Taichung, Taiwan
| | | | - Chung-Kai Chang
- National Synchrotron Radiation Research Centre, Hsinchu, Taiwan
| | - Hwo-Shuenn Sheu
- National Synchrotron Radiation Research Centre, Hsinchu, Taiwan
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5
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Piorkowski D, Blackledge TA. Punctuated evolution of viscid silk in spider orb webs supported by mechanical behavior of wet cribellate silk. Naturwissenschaften 2017; 104:67. [DOI: 10.1007/s00114-017-1489-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 07/01/2017] [Accepted: 07/04/2017] [Indexed: 01/09/2023]
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6
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Munro T, Putzeys T, Copeland CG, Xing C, Lewis RV, Ban H, Glorieux C, Wubbenhorst M. Investigation of synthetic spider silk crystallinity and alignment via electrothermal, pyroelectric, literature XRD, and tensile techniques. MACROMOLECULAR MATERIALS AND ENGINEERING 2017; 302:1600480. [PMID: 29430211 PMCID: PMC5804743 DOI: 10.1002/mame.201600480] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The processes used to create synthetic spider silk greatly affect the properties of the produced fibers. This paper investigates the effect of process variations during artificial spinning on the thermal and mechanical properties of the produced silk. Property values are also compared to the ones of the natural dragline silk of the N. clavipes spider, and to unprocessed (as-spun) synthetic silk. Structural characterization by scanning pyroelectric microscopy is employed to provide insight into the axial orientation of the crystalline regions of the fiber and is supported by XRD data. The results show that stretching and passage through liquid baths induce crystal formation and axial alignment in synthetic fibers, but with different structural organization than natural silks. Furthermore, an increase in thermal diffusivity and elastic modulus is observed with decreasing fiber diameter, trending towards properties of natural fiber. This effect seems to be related to silk fibers being subjected to a radial gradient during production.
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Affiliation(s)
- Troy Munro
- Mechanical Engineering Department, Brigham Young University, Provo, UT 84602, USA
| | - Tristan Putzeys
- Functional Organic Materials and Devices, Department of Chemical Engineering and Chemistry, TU/e Eindhoven University of Technology, 5600 MB Eindhoven, the Netherlands Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Heverlee B-3001, Belgium
| | - Cameron G Copeland
- Synthetic Bioproducts Center, Biology Dept., Utah State University, North Logan, UT 84341, USA
| | - Changhu Xing
- Mechanical and Aerospace Engineering Department, Utah State University, Logan, UT 84322, USA
| | - Randolph V Lewis
- Synthetic Bioproducts Center, Biology Dept., Utah State University, North Logan, UT 84341, USA
| | - Heng Ban
- Mechanical and Aerospace Engineering Department, Utah State University, Logan, UT 84322, USA
| | - Christ Glorieux
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Heverlee B-3001, Belgium
| | - Michael Wubbenhorst
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Heverlee B-3001, Belgium
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7
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The effect of ageing on the mechanical properties of the silk of the bridge spider Larinioides cornutus (Clerck, 1757). Sci Rep 2016; 6:24699. [PMID: 27156712 PMCID: PMC4860589 DOI: 10.1038/srep24699] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 03/23/2016] [Indexed: 12/04/2022] Open
Abstract
Spider silk is regarded as one of the best natural polymer fibers especially in terms of low density, high tensile strength and high elongation until breaking. Since only a few bio-engineering studies have been focused on spider silk ageing, we conducted nano-tensile tests on the vertical naturally spun silk fibers of the bridge spider Larinioides cornutus (Clerck, 1757) (Arachnida, Araneae) to evaluate changes in the mechanical properties of the silk (ultimate stress and strain, Young’s modulus, toughness) over time. We studied the natural process of silk ageing at different time intervals from spinning (20 seconds up to one month), comparing silk fibers spun from adult spiders collected in the field. Data were analyzed using Linear Mixed Models. We detected a positive trend versus time for the Young’s modulus, indicating that aged silks are stiffer and possibly less effective in catching prey. Moreover, we observed a negative trend for the ultimate strain versus time, attesting a general decrement of the resistance force. These trends are interpreted as being due to the drying of the silk protein chains and the reorientation among the fibers.
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8
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Xu D, Shi X, Thompson F, Weber WS, Mou Q, Yarger JL. Protein secondary structure of Green Lynx spider dragline silk investigated by solid-state NMR and X-ray diffraction. Int J Biol Macromol 2015; 81:171-9. [PMID: 26226457 PMCID: PMC4874476 DOI: 10.1016/j.ijbiomac.2015.07.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/23/2015] [Accepted: 07/24/2015] [Indexed: 01/22/2023]
Abstract
In this study, the secondary structure of the major ampullate silk from Peucetia viridans (Green Lynx) spiders is characterized by X-ray diffraction and solid-state NMR spectroscopy. From X-ray diffraction measurement, β-sheet nanocrystallites were observed and found to be highly oriented along the fiber axis, with an orientational order, fc≈0.98. The size of the nanocrystallites was determined to be on average 2.5nm×3.3nm×3.8nm. Besides a prominent nanocrystalline region, a partially oriented amorphous region was also observed with an fa≈0.89. Two-dimensional (13)C-(13)C through-space and through-bond solid-state NMR experiments were employed to elucidate structure details of P. viridans silk proteins. It reveals that β-sheet nanocrystallites constitutes 40.0±1.2% of the protein and are dominated by alanine-rich repetitive motifs. Furthermore, based upon the NMR data, 18±1% of alanine, 60±2% glycine and 54±2% serine are incorporated into helical conformations.
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Affiliation(s)
- Dian Xu
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States
| | - Xiangyan Shi
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States
| | - Forrest Thompson
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States
| | - Warner S Weber
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States
| | - Qiushi Mou
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States
| | - Jeffery L Yarger
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, United States.
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9
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Hilbrant M, Damen WGM. The embryonic origin of the ampullate silk glands of the spider Cupiennius salei. ARTHROPOD STRUCTURE & DEVELOPMENT 2015; 44:280-288. [PMID: 25882741 DOI: 10.1016/j.asd.2015.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 06/04/2023]
Abstract
Silk production in spiders is considered a key innovation, and to have been vital for the diversification of the clade. The evolutionary origin of the organs involved in spider silk production, however, and in particular of the silk glands, is poorly understood. Homologies have been proposed between these and other glands found in arachnids, but lacking knowledge of the embryonic development of spider silk glands hampers an evaluation of hypotheses. This study focuses on the embryonic origin of the largest silk glands of the spider Cupiennius salei, the major and minor ampullate glands. We show how the ampullate glands originate from ectodermal invaginations on the embryonic spinneret limb buds, in relation to morphogenesis of these buds. Moreover, we visualize the subsequent growth of the ampullate glands in sections of the early postembryonic stages. The invaginations are shown to correlate with expression of the proneural gene CsASH2, which is remarkable since it has been proposed that spider silk glands and their nozzles originate from sensory bristles. Hence, by confirming the ectodermal origin of spider silk glands, and by describing the (post-)embryonic morphogenesis of the ampullate glands, this work provides a starting point for further investigating into the genetic program that underlies their development.
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Affiliation(s)
- Maarten Hilbrant
- Institute for Genetics, University of Cologne, Zülpicher Straße 47a, 50674 Cologne, Germany; Institute for Developmental Biology, University of Cologne, Zülpicher Straße 47b, 50674 Cologne, Germany.
| | - Wim G M Damen
- Institute for Genetics, University of Cologne, Zülpicher Straße 47a, 50674 Cologne, Germany; Department of Genetics, Friedrich Schiller University, Jena, Philosophenweg 12, 07743 Jena, Germany.
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10
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Wang L, Culha U, Iida F. A dragline-forming mobile robot inspired by spiders. BIOINSPIRATION & BIOMIMETICS 2014; 9:016006. [PMID: 24434546 DOI: 10.1088/1748-3182/9/1/016006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Mobility of wheeled or legged machines can be significantly increased if they are able to move from a solid surface into a three-dimensional space. Although that may be achieved by addition of flying mechanisms, the payload fraction will be the limiting factor in such hybrid mobile machines for many applications. Inspired by spiders producing draglines to assist locomotion, the paper proposes an alternative mobile technology where a robot achieves locomotion from a solid surface into a free space. The technology resembles the dragline production pathway in spiders to a technically feasible degree and enables robots to move with thermoplastic spinning of draglines. As an implementation, a mobile robot has been prototyped with thermoplastic adhesives as source material of the draglines. Experimental results show that a dragline diameter range of 1.17-5.27 mm was achievable by the 185 g mobile robot in descending locomotion from the solid surface of a hanging structure with a power consumption of 4.8 W and an average speed of 5.13 cm min(-1). With an open-loop controller consisting of sequences of discrete events, the robot has demonstrated repeatable dragline formation with a relative deviation within -4% and a length close to the metre scale.
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Affiliation(s)
- Liyu Wang
- Bio-Inspired Robotics Lab, ETH Zurich, Leonhardstrasse 27, 8092 Zurich, Switzerland
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11
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Blamires SJ, Wu CC, Wu CL, Sheu HS, Tso IM. Uncovering Spider Silk Nanocrystalline Variations That Facilitate Wind-Induced Mechanical Property Changes. Biomacromolecules 2013; 14:3484-90. [DOI: 10.1021/bm400803z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sean J. Blamires
- Department
of Life Science, Tunghai University, Taichung 40704, Taiwan
| | - Chao-Chia Wu
- Department
of Life Science, National Chung-Hsing University, Taichung 40227, Taiwan
| | - Chung-Lin Wu
- Center
for Measurement Standards, Industrial Technology Research Institute, Hsinchu 30011, Taiwan
| | - Hwo-Shuenn Sheu
- National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan
| | - I-Min Tso
- Department
of Life Science, Tunghai University, Taichung 40704, Taiwan
- Department
of Life Science, National Chung-Hsing University, Taichung 40227, Taiwan
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12
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Koski KJ, Akhenblit P, McKiernan K, Yarger JL. Non-invasive determination of the complete elastic moduli of spider silks. NATURE MATERIALS 2013; 12:262-7. [PMID: 23353627 DOI: 10.1038/nmat3549] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 12/13/2012] [Indexed: 05/20/2023]
Abstract
Spider silks possess nature's most exceptional mechanical properties, with unrivalled extensibility and high tensile strength. Unfortunately, our understanding of silks is limited because the complete elastic response has never been measured-leaving a stark lack of essential fundamental information. Using non-invasive, non-destructive Brillouin light scattering, we obtain the entire stiffness tensors (revealing negative Poisson's ratios), refractive indices, and longitudinal and transverse sound velocities for major and minor ampullate spider silks: Argiope aurantia, Latrodectus hesperus, Nephila clavipes, Peucetia viridans. These results completely quantify the linear elastic response for all possible deformation modes, information unobtainable with traditional stress-strain tests. For completeness, we apply the principles of Brillouin imaging to spatially map the elastic stiffnesses on a spider web without deforming or disrupting the web in a non-invasive, non-contact measurement, finding variation among discrete fibres, junctions and glue spots. Finally, we provide the stiffness changes that occur with supercontraction.
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Affiliation(s)
- Kristie J Koski
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
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13
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Blamires SJ, Wu CL, Blackledge TA, Tso IM. Post-secretion processing influences spider silk performance. J R Soc Interface 2012; 9:2479-87. [PMID: 22628213 DOI: 10.1098/rsif.2012.0277] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Phenotypic variation facilitates adaptations to novel environments. Silk is an example of a highly variable biomaterial. The two-spidroin (MaSp) model suggests that spider major ampullate (MA) silk is composed of two proteins-MaSp1 predominately contains alanine and glycine and forms strength enhancing β-sheet crystals, while MaSp2 contains proline and forms elastic spirals. Nonetheless, mechanical properties can vary in spider silks without congruent amino acid compositional changes. We predicted that post-secretion processing causes variation in the mechanical performance of wild MA silk independent of protein composition or spinning speed across 10 species of spider. We used supercontraction to remove post-secretion effects and compared the mechanics of silk in this 'ground state' with wild native silks. Native silk mechanics varied less among species compared with 'ground state' silks. Variability in the mechanics of 'ground state' silks was associated with proline composition. However, variability in native silks did not. We attribute interspecific similarities in the mechanical properties of native silks, regardless of amino acid compositions, to glandular processes altering molecular alignment of the proteins prior to extrusion. Such post-secretion processing may enable MA silk to maintain functionality across environments, facilitating its function as a component of an insect-catching web.
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Affiliation(s)
- Sean J Blamires
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan
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14
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BLAMIRES SEANJ, WU CHUNLIN, BLACKLEDGE TODDA, TSO IMIN. Environmentally induced post-spin property changes in spider silks: influences of web type, spidroin composition and ecology. Biol J Linn Soc Lond 2012. [DOI: 10.1111/j.1095-8312.2012.01884.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Lepore E, Marchioro A, Isaia M, Buehler MJ, Pugno NM. Evidence of the most stretchable egg sac silk stalk, of the European spider of the year Meta menardi. PLoS One 2012; 7:e30500. [PMID: 22347380 PMCID: PMC3275603 DOI: 10.1371/journal.pone.0030500] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 12/16/2011] [Indexed: 11/29/2022] Open
Abstract
Spider silks display generally strong mechanical properties, even if differences between species and within the same species can be observed. While many different types of silks have been tested, the mechanical properties of stalks of silk taken from the egg sac of the cave spider Meta menardi have not yet been analyzed. Meta menardi has recently been chosen as the "European spider of the year 2012", from the European Society of Arachnology. Here we report a study where silk stalks were collected directly from several caves in the north-west of Italy. Field emission scanning electron microscope (FESEM) images showed that stalks are made up of a large number of threads, each of them with diameter of 6.03 ± 0.58 µm. The stalks were strained at the constant rate of 2 mm/min, using a tensile testing machine. The observed maximum stress, strain and toughness modulus, defined as the area under the stress-strain curve, are 0.64 GPa, 751% and 130.7 MJ/m(3), respectively. To the best of our knowledge, such an observed huge elongation has never been reported for egg sac silk stalks and suggests a huge unrolling microscopic mechanism of the macroscopic stalk that, as a continuation of the protective egg sac, is expected to be composed by fibres very densely and randomly packed. The Weibull statistics was used to analyze the results from mechanical testing, and an average value of Weibull modulus (m) is deduced to be in the range of 1.5-1.8 with a Weibull scale parameter (σ(0)) in the range of 0.33-0.41 GPa, showing a high coefficient of correlation (R(2) = 0.97).
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Affiliation(s)
- Emiliano Lepore
- Laboratory of Bio-inspired Nanomechanics “Giuseppe Maria Pugno”, Department of Structural Engineering, Politecnico di Torino, Torino, Italy
| | - Andrea Marchioro
- Laboratory of Bio-inspired Nanomechanics “Giuseppe Maria Pugno”, Department of Structural Engineering, Politecnico di Torino, Torino, Italy
| | - Marco Isaia
- Laboratory of Ecology and Terrestrial Ecosystems, Department of Human and Animal Biology, University of Torino, Torino, Italy
| | - Markus J. Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Center for Materials Science and Engineering, and Center for Computational Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Nicola M. Pugno
- Laboratory of Bio-inspired Nanomechanics “Giuseppe Maria Pugno”, Department of Structural Engineering, Politecnico di Torino, Torino, Italy
- National Institute of Nuclear Physics, National Laboratories of Frascati, Frascati, Italy
- National Institute of Metrological Research, Torino, Italy
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