Identification and dynamics of polyglycine II nanocrystals in Argiope trifasciata flagelliform silk

Spider silks combine a significant number of desirable characteristics in one material, including large tensile strength and strain at breaking, biocompatibility, and the possibility of tailoring their properties. Major ampullate gland silk (MAS) is the most studied silk and their properties are explained by a double lattice of hydrogen bonds and elastomeric protein chains linked to polyalanine β-nanocrystals. However, many basic details regarding the relationship between composition, microstructure and properties in silks are still lacking. Here we show that this relationship can be traced in flagelliform silk (Flag) spun by Argiope trifasciata spiders after identifying a phase consisting of polyglycine II nanocrystals. The presence of this phase is consistent with the dominant presence of the –GGX– and –GPG– motifs in its sequence. In contrast to the passive role assigned to polyalanine nanocrystals in MAS, polyglycine II nanocrystals can undergo growing/collapse processes that contribute to increase toughness and justify the ability of Flag to supercontract.

Mechanical behaviour and formation process of silkworm silk gut

High performance silk fibers were produced directly from the silk glands of silkworms ("Bombyx mori") following an alternative route to natural spinning. This route is based on a traditional procedure that consists of soaking the silk glands in a vinegar solution and stretching them by hand leading to the so called silkworm guts. Here we present, to the authors’ best knowledge, the first comprehensive study on the formation, properties and microstructure of silkworm gut fibers. Comparison of the tensile properties and microstructural organization of the silkworm guts with those of naturally spun fibers allows gain of a deeper insight into the mechanisms that lead to the formation of the fiber, as well as the relationship between the microstructure and properties of these materials. In this regard, it is proved that an acidic environment and subsequent application of tensile stress in the range of 1000 kPa are sufficient conditions for the formation of a silk fiber.

The New Silk Road: a versatile instrument in China’s policy. OSW Commentary No. 161, February 10 2015

Introduction. The Chinese leader Xi Jinping presented the concept of the New Silk Road – a collection of land and maritime routes – in autumn 2013. Initially, it envisaged the creation of a network of infrastructural connections, mainly transport corridors, between China and its most important economic partner – Europe. The concept grew in importance throughout 2014 to become the key instrument of China’s foreign policy, especially in the areas of public diplomacy and soft power. Towards the end of 2014, the Chinese government announced it would establish a Silk Road Fund worth US$40 billion. The New Silk Road idea is a flexible formula used by China in its dialogue with many other countries. Its inclusive nature helps contribute to diluting the negative impression caused by China’s rapid economic expansion and assertiveness in foreign policy, especially with regard to its neighbours. The process of implementing the New Silk Road concept will allow China to expand its influence within its neighbourhood: in Central and South-Eastern Asia. The New Silk Road will be an alternative point of reference to the US dominance and Russian integration projects in these regions. The concept will legitimise and facilitate the growth of China’s influence in the transit countries on the route to Western Europe, i.e. in the Middle East (Arab countries, Israel and Turkey, the Horn of Africa and Central Europe (the Balkans and the Visegrad Group countries). This concept is also essential for China’s domestic policy. It has become one of Xi Jinping’s main political projects. It will boost the development of China’s central and western provinces. The fact that the concept is open and not fully defined means that it will be a success regardless of the extent to which it will be implemented in practice. Its flexible nature allows China to continue investments already initiated bilaterally and to present them as components of the New Silk Road concept.

Tomorrow’s Silk Road: Assessing an EU-China Free Trade Agreement

This book provides an independent and in-depth contribution on the status of bilateral economic exchanges and persistent trade barriers between the European Union and China. A second objective is to encourage a frank and open dialogue, based on a scientific evaluation and without prejudice, of the possibility of a preferential trade agreement between the two sides. The study, commissioned by the Foreign Trade Association, was carried out by CEPS, in cooperation with the World Trade Institute (WTI) at the University of Bern. Jacques Pelkmans, CEPS Senior Research Fellow, served as overall study leader and Joseph Francois, Managing Director and Professor of Economics at the World Trade Institute, led the WTI team.

Tomorrow's silk road: Assessing an EU-China Free Trade Agreement.

Foreword. The Foreign Trade Association, which represents the European and international distribution and retail sector, commissioned this study in light of the importance of China as a sourcing country and its attractiveness as a rapidly growing consumer market. We believe that open borders and free trade can contribute to a broader choice and lower costs for consumers and create growth and employment in both Europe and China. This independent study aims to provide an in-depth contribution on the status of bilateral economic exchanges and persistent trade barriers that exist between the European Union and China. The second objective of the report is to encourage a frank and open dialogue, based on a scientific evaluation and without prejudice, on the possibility of a preferential trade agreement between the two sides. This study should be read by anyone who is interested in economic relations between the EU and China and in trade policy in general. The report provides many interesting findings and raises a number of surprising points. Overall, this study is one of the most significant contributions to the discourse on EU-China relations in recent years. We hope that this study will stimulate fresh thoughts on the benefits of closer future cooperation between two regions that have been interlinked since the times of antiquity and the first Silk Road.

Genetically engineered silk and genipin-enhanced fibrin hydrogel for annulus fibrosus repair

INTRODUCTION: Around 80% of people are affected by low back pain at least once in their life, often caused by trauma provoking intervertebral disc (IVD) herniation and/or IVD degeneration. Apart from some promising approaches for nucleus pulposus repair, so far no treatment or repair is available for the outer fibrous tissue, annulus fibrosus (AF). We aimed for sealing and repairing an AF injury in a bovine IVD organ culture model in vitro over 14 days under different loading conditions. For this purpose, a silk fleece composite from Bombyx mori silk was combined with genipin-enhanced fibrin hydrogel [1]. METHODS: Bovine IVDs of 12-17 months old animals were isolated by first removing all surrounding tissue, followed by cutting out the IVDs [2]. Culturing of discs occurred in high glucose Dulbecco's Modified Eagle Medium (HG-DMEM) supplemented with 5% serum as previously described. On the next day, injury was induced using a 2mm biopsy punch (Polymed, Switzerland). The formed cavity was filled with (0.4%) genipin-enhanced human based fibrin hydrogel (35- 55mg/mL human fibrinogen, Baxter, Austria) and sealed with a silk fleece-membrane composite (Spintec Engineering, Germany). Different culture conditions were applied: free swelling, static diurnal load of 0.2MPa for 8h/d and complex loading at 0.2MPa compression combined with ± 2° torsion at 0.2Hz for 8h/d. Complex loading was applied by a custom built 2 degree of freedom bioreactor [3]. After 14 days of culture cell activity was determined with resazurin assay. Additionally, glycosaminoglycan (dimethyl-methylene blue), DNA (Hoechst) and collagen content (hydroxy-proline) were determined. Finally, real-time qPCR of major IVD marker genes was performed. RESULTS: The silk seal closing the injury site could successfully withstand the forces of all three loading conditions with no misplacement over the two weeks’ culture. Nevertheless, disc height of the repaired discs did not significantly differ from the injured group. The disc phenotype could be maintained as demonstrated by biochemical analysis of gene expression, cell activity, DNA-, collagen- and GAG content. The silk itself was evaluated to be highly biocompatible for hMSC, as revealed by cytotoxicity assays. DISCUSSION & CONCLUSIONS: The silk can be considered a highly-elastic and biocompatible material for AF closure and the genipin-enhanced fibrin hydrogel has also good biomechanical properties. However, the cyto-compatibility of genipin seems rather poor and other hydrogels and/or cross-linkers should be looked into. REFERENCES: 1 C.C. Guterl et al. (2014) Characterization of Mechanics and Cytocompatibility of Fibrin Genipin Annulus Fibrosus Sealant with the Addition of Cell Adhesion Molecules, Tissue Eng Part A 2 S.C. Chan, B. Gantenbein-Ritter (2012) Preparation of intact bovine tail intervertebral discs for organ culture, J Vis Exp 3 B Gantenbein et al. (2015) Organ Culture Bioreactors - Platforms to Study Human Intervertebral Disc Degeneration and Regenerative Therapy, Curr Stem Cell Res Ther [epub ahead of print] ACKNOWLEDGEMENTS: This project is supported by the Gebert Rüf Stiftung project # GRS-028/13.

Hearing: in the matter of the minimum wage recommendations of Special Industry Committee no. 17-A for the silk, rayon, and nylon underwear division and the general division of the needlework and fabricated textile products industry in Puerto Rico, August 29 and 30, 1955.

Mode of access: Internet.

The new American gardener; containing practical directions on the culture of fruits and vegetables; including landscape and ornamental gardening, grape-vines, silk, strawberries, &c. &c.

Mode of access: Internet.