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Fiber science

posted Mar 4, 2011, 8:38 AM by rajesh gk

Title

Effect of methyl alcohol on the morphology and conformational characteristics of silk sericin.

Authors

Lee K, Kweon H, Yeo JH, Woo SO, Lee YW, Cho CS, Kim KH, Park YH.

Department of Sericulture and Entomology, National Institute of Agriculture and Technology, 441-100, Suwon, South Korea

Journal

Int J Biol Macromol. 2003 Nov;33(1-3):75-80.

Abstract

Effects of methyl alcohol on the morphology and conformational characteristics of silk sericin (SS) were studied. Scanning electron microscope showed that morphology of SS lyophilized was dramatically changed from sponge-like structure to spherical fine particle type. X-ray diffraction method, infrared spectroscopy, and differential scanning calorimetry showed that the conformation of SS was random coil structure regardless of the addition of methyl alcohol. On the other hand, circular dichroism showed that the molecular states of SS were more densely packed.

Citation

http://www.ncbi.nlm.nih.gov/pubmed/14599587 PMID: 14599587 [PubMed - indexed for MEDLINE]

 

Title

Application of recombinant fusion proteins for tissue engineering.

Authors

Nagaoka M, Jiang HL, Hoshiba T, Akaike T, Cho CS.

Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, 226-8501, Japan.

Journal

Ann Biomed Eng. 2010 Mar;38(3):683-93. Epub 2010 Feb 4.

Abstract

Extracellular matrix (ECM) plays important roles in tissue engineering because cellular growth and differentiation, in the two-dimensional cell culture as well as in the three-dimensional space of the developing organism, require ECM with which the cells can interact. Also, the development of new synthetic ECMs is very important because ECMs facilitate the localization and delivery of cells to the specific sites in the body. Therefore, the development of synthetic ECMs to replace the natural ECMs is increasingly essential and promising in tissue engineering. Recombinant genetic engineering method has enabled the synthesis of protein-based polymers with precisely controlled functionalities for the development of new synthetic ECMs. In this review, the design and construction of structure-based recombinant fusion proteins such as elastin-like polymers (ELPs) and silk-like polymers (SLPs), cell-bound growth factor-based recombinant fusion proteins such as basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF), hybrid system composed of recombinant protein and synthetic polymer, and E-cadherin-based fusion protein by recombinant genetic engineering were explained for application of the synthetic ECMs. Modulation of mechanical properties, stimuli-sensitivity, biodegradation and cell recognition can be achieved through precise control of sequence, length, hydrophobicity and cell binding domain by recombinant genetic engineering.

Citation

http://www.ncbi.nlm.nih.gov/pubmed/20131097 PMID: 20131097 [PubMed - indexed for MEDLINE]

 

Title

Animal silks: their structures, properties and artificial production.

Authors

Fu C, Shao Z, Fritz V.

Key Laboratory of Molecular Engineering of Polymers of Ministry of Education, Advanced Materials Laboratory, Department of Macromolecular Science, Fudan University, Shanghai 200433, PR China.

Journal

Chem Commun (Camb). 2009 Nov 21;(43):6515-29. Epub 2009 Sep 8.

Abstract

This feature article reviews recent progress in the understanding of the hierarchically organized structures, the perfectly balanced mechanical properties and the structure-property relationship of the natural animal silk fibres, as well as the experimental attempts to fabricate man-made silk fibres by means of wet spinning, dry spinning, electrospinning and transgenosis.

Citation

http://www.ncbi.nlm.nih.gov/pubmed/19865641 PMID: 19865641 [PubMed - indexed for MEDLINE]

 

Title

Mechanical response of silk crystalline units from force-distribution analysis. Free PMC Article

Authors

Xiao S, Stacklies W, Cetinkaya M, Markert B, Gräter F.

CAS-MPG Partner Institute for Computational Biology, Shanghai, China.

Journal

Biophys J. 2009 May 20;96(10):3997-4005.

Abstract

The outstanding mechanical toughness of silk fibers is thought to be caused by embedded crystalline units acting as cross links of silk proteins in the fiber. Here, we examine the robustness of these highly ordered beta-sheet structures by molecular dynamics simulations and finite element analysis. Structural parameters and stress-strain relationships of four different models, from spider and Bombyx mori silk peptides, in antiparallel and parallel arrangement, were determined and found to be in good agreement with x-ray diffraction data. Rupture forces exceed those of any previously examined globular protein many times over, with spider silk (poly-alanine) slightly outperforming Bombyx mori silk ((Gly-Ala)(n)). All-atom force distribution analysis reveals both intrasheet hydrogen-bonding and intersheet side-chain interactions to contribute to stability to similar extent. In combination with finite element analysis of simplified beta-sheet skeletons, we could ascribe the distinct force distribution pattern of the antiparallel and parallel silk crystalline units to the difference in hydrogen-bond geometry, featuring an in-line or zigzag arrangement, respectively. Hydrogen-bond strength was higher in antiparallel models, and ultimately resulted in higher stiffness of the crystal, compensating the effect of the mechanically disadvantageous in-line hydrogen-bond geometry. Atomistic and coarse-grained force distribution patterns can thus explain differences in mechanical response of silk crystals, opening up the road to predict full fiber mechanics.

Citation

PMID: 19450471 [PubMed - indexed for MEDLINE]PMCID: PMC2712141

 

Title

Solution structure of eggcase silk protein and its implications for silk fiber formation. Free PMC Article

Authors

Lin Z, Huang W, Zhang J, Fan JS, Yang D.

Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, 117543 Singapore. dbslinz@nus.edu.sg

Journal

Proc Natl Acad Sci U S A. 2009 Jun 2;106(22):8906-11. Epub 2009 May 20.

Abstract

Spider silks are renowned for their excellent mechanical properties and biomimetic and industrial potentials. They are formed from the natural refolding of water-soluble fibroins with alpha-helical and random coil structures in silk glands into insoluble fibers with mainly beta-structures. The structures of the fibroins at atomic resolution and silk formation mechanism remain largely unknown. Here, we report the 3D structures of individual domains of a approximately 366-kDa eggcase silk protein that consists of 20 identical type 1 repetitive domains, one type 2 repetitive domain, and conserved nonrepetitive N- and C-terminal domains. The structures of the individual domains in solution were determined by using NMR techniques. The domain interactions were investigated by NMR and dynamic light-scattering techniques. The formation of micelles and macroscopic fibers from the domains was examined by electron microscopy. We find that either of the terminal domains covalently linked with at least one repetitive domain spontaneously forms micelle-like structures and can be further transformed into fibers at > or = 37 degrees C and a protein concentration of > 0.1 wt%. Our biophysical and biochemical experiments indicate that the less hydrophilic terminal domains initiate the assembly of the proteins and form the outer layer of the micelles whereas the more hydrophilic repetitive domains are embedded inside to ensure the formation of the micelle-like structures that are the essential intermediates in silk formation. Our results establish the roles of individual silk protein domains in fiber formation and provide the basis for designing miniature fibroins for producing artificial silks.

Citation

PMID: 19458259 [PubMed - indexed for MEDLINE]PMCID: PMC2690042

 

Title

Biodegradation of silk biomaterials. Free PMC Article

Authors

Cao Y, Wang B.

Jiangsu University of Science and Technology, Zhenjiang Jiangsu, P R China. bestmancy@163.com

Journal

Int J Mol Sci. 2009 Mar 31;10(4):1514-24.

Abstract

Silk fibroin from the silkworm, Bombyx mori, has excellent properties such as biocompatibility, biodegradation, non-toxicity, adsorption properties, etc. As a kind of ideal biomaterial, silk fibroin has been widely used since it was first utilized for sutures a long time ago. The degradation behavior of silk biomaterials is obviously important for medical applications. This article will focus on silk-based biomaterials and review the degradation behaviors of silk materials.

Citation

PMID: 19468322 [PubMed]PMCID: PMC2680630Free PMC Article

 

Title

Low molecular weight silk fibroin increases alkaline phosphatase and type I collagen expression in MG63 cells.

Authors

Kim JY, Choi JY, Jeong JH, Jang ES, Kim AS, Kim SG, Kweon HY, Jo YY, Yeo JH.

Department of Oral and Maxillofacial Surgery, Hallym University, Chuncheon 200-702, Korea.

Journal

BMB Rep. 2010 Jan;43(1):52-6.

Abstract

Silk fibroin, produced by the silkworm Bombyx mori, has been widely studied as a scaffold in tissue engineering. Although it has been shown to be slowly biodegradable, cellular responses to degraded silk fibroin fragments are largely unknown. In this study, silk fibroin was added to MG-63 cell cultures, and changes in gene expression in the MG-63 cells were screened by DNA microarray analysis. Genes showing a significant (2-fold) change were selected and their expression changes confirmed by quantitative RT-PCR and western blotting. DNA microarray results showed that alkaline phosphatase (ALP), collagen type-I alpha-1, fibronectin, and transforming growth factor-beta1 expressions significantly increased. The effect of degraded silk fibroin on osteoblastogenic gene expression was confirmed by observing up-regulation of ALP activity in MG-63 cells. The finding that small fragments of silk fibroin are able to increase the expression of osteoblastogenic genes suggests that controlled degradation of silk fibroin might accelerate new bone formation. [BMB reports 2010; 43(1): 52-56].

Citation

PMID: 20132736 [PubMed - indexed for MEDLINE] Free Article

 

Title

The elaborate structure of spider silk: structure and function of a natural high performance fiber.

Authors

Römer L, Scheibel T.

Journal

Prion. 2008 Oct;2(4):154-61. Epub 2008 Oct 20.

Abstract

Biomaterials, having evolved over millions of years, often exceed man-made materials in their properties. Spider silk is one outstanding fibrous biomaterial which consists almost entirely of large proteins. Silk fibers have tensile strengths comparable to steel and some silks are nearly as elastic as rubber on a weight to weight basis. In combining these two properties, silks reveal a toughness that is two to three times that of synthetic fibers like Nylon or Kevlar. Spider silk is also antimicrobial, hypoallergenic and completely biodegradable. This article focuses on the structure-function relationship of the characterized highly repetitive spider silk spidroins and their conformational conversion from solution into fibers. Such knowedge is of crucial importance to understanding the intrinsic properties of spider silk and to get insight into the sophisticated assembly processes of silk proteins. This review further outlines recent progress in recombinant production of spider silk proteins and their assembly into distinct polymer materials as a basis for novel products.

Citation

PMID: 19221522 [PubMed - indexed for MEDLINE]PMCID: PMC2658765 Free PMC

 

Title

Silks produced by insect labial glands. Free PMC Article

Authors

Sehnal F, Sutherland T.

Biology Centre ASCR, Ceské Budejovice, Czech Republic. sehnal@bc.cas.cz

Journal

Prion. 2008 Oct;2(4):145-53. Epub 2008 Oct 20.

Abstract

Insect silks are secreted from diverse gland types; this chapter deals with the silks produced by labial glands of Holometabola (insects with pupa in their life cycle). Labial silk glands are composed of a few tens or hundreds of large polyploid cells that secrete polymerizing proteins which are stored in the gland lumen as a semi-liquid gel. Polymerization is based on weak molecular interactions between repetitive amino acid motifs present in one or more silk proteins; cross-linking by disulfide bonds may be important in the silks spun under water. The mechanism of long-term storage of the silk dope inside the glands and its conversion into the silk fiber during spinning is not fully understood. The conversion occurs within seconds at ambient temperature and pressure, under minimal drawing force and in some cases under water. The silk filament is largely built of proteins called fibroins and in Lepidoptera and Trichoptera coated by glue-type proteins known as sericins. Silks often contain small amounts of additional proteins of poorly known function. The silk components controlling dope storage and filament formation seem to be conserved at the level of orders, while the nature of polymerizing motifs in the fibroins, which determine the physical properties of silk, differ at the level of family and even genus. Most silks are based on fibroin beta-sheets interrupted with other structures such as alpha-helices but the silk proteins of certain sawflies have predominantly a collagen-like or polyglycine II arrangement and the silks of social Hymenoptera are formed from proteins in a coiled coil arrangement.

Citation

PMID: 19221523 [PubMed - indexed for MEDLINE]PMCID: PMC2658764

 

Title

A protocol for the production of recombinant spider silk-like proteins for artificial fiber spinning. Free PMC Article

Authors

Teulé F, Cooper AR, Furin WA, Bittencourt D, Rech EL, Brooks A, Lewis RV.

Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071, USA.

Journal

Nat Protoc. 2009;4(3):341-55.

Abstract

The extreme strength and elasticity of spider silks originate from the modular nature of their repetitive proteins. To exploit such materials and mimic spider silks, comprehensive strategies to produce and spin recombinant fibrous proteins are necessary. This protocol describes silk gene design and cloning, protein expression in bacteria, recombinant protein purification and fiber formation. With an improved gene construction and cloning scheme, this technique is adaptable for the production of any repetitive fibrous proteins, and ensures the exact reproduction of native repeat sequences, analogs or chimeric versions. The proteins are solubilized in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) at 25-30% (wt/vol) for extrusion into fibers. This protocol, routinely used to spin single micrometer-size fibers from several recombinant silk-like proteins from different spider species, is a powerful tool to generate protein libraries with corresponding fibers for structure-function relationship investigations in protein-based biomaterials. This protocol may be completed in 40 d.

Citation

PMID: 19229199 [PubMed - indexed for MEDLINE]PMCID: PMC2720753

 

Title

Stabilization of enzymes in silk films. Free PMC Article

Authors

Lu S, Wang X, Lu Q, Hu X, Uppal N, Omenetto FG, Kaplan DL.

Departments of Biomedical Engineering and Physics, Tufts University, Medford, Massachusetts 02155, USA.

Journal

Biomacromolecules. 2009 May 11;10(5):1032-42.

Abstract

Material systems are needed that promote stabilization of entrained molecules, such as enzymes or therapeutic proteins, without destroying their activity. We demonstrate that the unique structure of silk fibroin protein, when assembled into the solid state, establishes an environment that is conducive to the stabilization of entrained proteins. Enzymes (glucose oxidase, lipase, and horseradish peroxidase) entrapped in these films over 10 months retained significant activity, even when stored at 37 degrees C, and in the case of glucose oxidase did not lose any activity. Further, the mode of processing of the silk protein into the films could be correlated to the stability of the enzymes. The relationship between processing and stability offers a large suite of conditions within which to optimize such stabilization processes. Overall, the techniques reported here result in materials that stabilize enzymes to an extent, without the need for cryoprotectants, emulsifiers, covalent immobilization, or other treatments. Further, these systems are amenable to optical applications and characterization, environmental distribution without refrigeration, are ingestible, and offer potential use in vivo, because silk materials are biocompatible and FDA approved, degradable with proteases, and currently used in biomedical devices.

Citation

PMID: 19323497 [PubMed - indexed for MEDLINE]PMCID: PMC2705330

 

Title

Biomimicry as a route to new materials: what kinds of lessons are useful? Free Article

Authors

Reed EJ, Klumb L, Koobatian M, Viney C.

School of Engineering, University of California at Merced, PO Box 2039, Merced, CA 95344, USA.

Journal

Philos Transact A Math Phys Eng Sci. 2009 Apr 28;367(1893):1571-85.

Abstract

We consider the attributes of a successful engineered material, acknowledging the contributions of composition and processing to properties and performance. We recognize the potential for relevant lessons to be learned from nature, at the same time conceding both the limitations of such lessons and our need to be selective. We then give some detailed attention to the molecular biomimicry of filamentous phage, the process biomimicry of silk and the structure biomimicry of hippopotamus 'sweat', in each case noting that the type of lesson now being learned is not the same as the potential lesson that originally motivated the study.

Citation

PMID: 19324724 [PubMed - indexed for MEDLINE]

 

Title

Mimicking biopolymers on a molecular scale: nano(bio)technology based on engineered proteins. Free Article

Authors

Grunwald I, Rischka K, Kast SM, Scheibel T, Bargel H.

Department of Adhesive Bonding Technology and Surfaces, Fraunhofer Institute for Manufacturing Technology and Applied Materials Research (IFAM)28359 Bremen, Germany.

Journal

Philos Transact A Math Phys Eng Sci. 2009 May 13;367(1894):1727-47.

Abstract

Proteins are ubiquitous biopolymers that adopt distinct three-dimensional structures and fulfil a multitude of elementary functions in organisms. Recent systematic studies in molecular biology and biotechnology have improved the understanding of basic functional and architectural principles of proteins, making them attractive candidates as concept generators for technological development in material science, particularly in biomedicine and nano(bio)technology. This paper highlights the potential of molecular biomimetics in mimicking high-performance proteins and provides concepts for applications in four case studies, i.e. spider silk, antifreeze proteins, blue mussel adhesive proteins and viral ion channels.

Citation

PMID: 19376768 [PubMed - indexed for MEDLINE]

 

Title

Engineered disulfides improve mechanical properties of recombinant spider silk. Free PMC Article

Authors

Grip S, Johansson J, Hedhammar M.

Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, The Biomedical Centre, Uppsala 751 23, Sweden.

Journal

Protein Sci. 2009 May;18(5):1012-22.

Abstract

Nature's high-performance polymer, spider silk, is composed of specific proteins, spidroins, which form solid fibers. So far, fibers made from recombinant spidroins have failed in replicating the extraordinary mechanical properties of the native material. A recombinant miniature spidroin consisting of four poly-Ala/Gly-rich tandem repeats and a nonrepetitive C-terminal domain (4RepCT) can be isolated in physiological buffers and undergoes self assembly into macrofibers. Herein, we have made a first attempt to improve the mechanical properties of 4RepCT fibers by selective introduction of AA --> CC mutations and by letting the fibers form under physiologically relevant redox conditions. Introduction of AA --> CC mutations in the first poly-Ala block in the miniature spidroin increases the stiffness and tensile strength without changes in ability to form fibers, or in fiber morphology. These improved mechanical properties correlate with degree of disulfide formation. AA --> CC mutations in the forth poly-Ala block, however, lead to premature aggregation of the protein, possibly due to disulfide bonding with a conserved Cys in the C-terminal domain. Replacement of this Cys with a Ser, lowers thermal stability but does not interfere with dimerization, fiber morphology or tensile strength. These results show that mutagenesis of 4RepCT can reveal spidroin structure-activity relationships and generate recombinant fibers with improved mechanical properties.

Citation

PMID: 19388023 [PubMed - indexed for MEDLINE]PMCID: PMC2771303

 

Title

Greatly increased toughness of infiltrated spider silk. Free Article

Authors

Lee SM, Pippel E, Gösele U, Dresbach C, Qin Y, Chandran CV, Bräuniger T, Hause G, Knez M.

Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle, Germany. smlee@mpi-halle.de

Journal

Science. 2009 Apr 24;324(5926):488-92.

Abstract

In nature, tiny amounts of inorganic impurities, such as metals, are incorporated in the protein structures of some biomaterials and lead to unusual mechanical properties of those materials. A desire to produce these biomimicking new materials has stimulated materials scientists, and diverse approaches have been attempted. In contrast, research to improve the mechanical properties of biomaterials themselves by direct metal incorporation into inner protein structures has rarely been tried because of the difficulty of developing a method that can infiltrate metals into biomaterials, resulting in a metal-incorporated protein matrix. We demonstrated that metals can be intentionally infiltrated into inner protein structures of biomaterials through multiple pulsed vapor-phase infiltration performed with equipment conventionally used for atomic layer deposition (ALD). We infiltrated zinc (Zn), titanium (Ti), or aluminum (Al), combined with water from corresponding ALD precursors, into spider dragline silks and observed greatly improved toughness of the resulting silks. The presence of the infiltrated metals such as Al or Ti was verified by energy-dispersive x-ray (EDX) and nuclear magnetic resonance spectra measured inside the treated silks. This result of enhanced toughness of spider silk could potentially serve as a model for a more general approach to enhance the strength and toughness of other biomaterials.

Citation

PMID: 19390040 [PubMed - indexed for MEDLINE]

 

Title

Antheraea pernyi silk fiber: a potential resource for artificially biospinning spider dragline silk.

Authors

Zhang Y, Yang H, Shao H, Hu X.

State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China.

Journal

J Biomed Biotechnol. 2010;2010:683962. Epub 2010 May 5.

Abstract

The outstanding properties of spider dragline silk are likely to be determined by a combination of the primary sequences and the secondary structure of the silk proteins. Antheraea pernyi silk has more similar sequences to spider dragline silk than the silk from its domestic counterpart, Bombyx mori. This makes it much potential as a resource for biospinning spider dragline silk. This paper further verified its possibility as the resource from the mechanical properties and the structures of the A. pernyi silks prepared by forcible reeling. It is surprising that the stress-strain curves of the A. pernyi fibers show similar sigmoidal shape to those of spider dragline silk. Under a controlled reeling speed of 95 mm/s, the breaking energy was 1.04 x 10(5) J/kg, the tensile strength was 639 MPa and the initial modulus was 9.9 GPa. It should be noted that this breaking energy of the A. pernyi silk approaches that of spider dragline silk. The tensile properties, the optical orientation and the beta-sheet structure contents of the silk fibers are remarkably increased by raising the spinning speeds up to 95 mm/s.

Citation

PMID: 20454537 [PubMed - in process]PMCID: PMC2864894 Free PMC Article

 

Title

Structure and Property of Mulberry Fiber

Authors

Ruili Cong ; Weiguo Dong

Journal

Modern Applied Science, 2009, 1(4)

Abstract

In this paper, the chemical ingredients of mulberry bast was tested by quantitative analysis. Our objective was to <br />substitute the slow and difficult to control retting process by a fast and well controlled process, i.e. the two-step boiled <br />process treatment (TSBP) of mulberry bast which was treated by mechanism. During the TSBP treatment the pectin, <br />Lignin and hemicelluloses are hydrolysed and rendered in water or alkali-soluble, the fibers being more easily <br />degummed. The TSBP treatment was among the best conditions for the degumming and individualisation of the fibers. The two-step boiled samples were tested. The results indicated that the length of mulberry fiber is 23.0-35.0mm, <br />fineness is 2.3-3.5 dT, breaking tenacity is 5.0-10.0cN/dT, breaking extension rate is 3.5-5.5%, moisture regain is <br />9-10%. The samples were observed by scanning electron microscopy (SEM), and the morphological aspects of the <br />mulberry fibers are discussed.Structural disruption was observed by X-ray measurement. 

Citation

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posted Jul 5, 2010, 2:09 AM by rajesh gk

Title

Solid-State NMR Comparison of Various Spiders' Dragline Silk Fiber.

Authors

Creager MS, Jenkins JE, Thagard-Yeaman LA, Brooks AE, Jones JA, Lewis RV, Holland GP, Yarger JL.

 

Department of Molecular Biology and Macromolecular Core Facility, University of Wyoming, Laramie, Wyoming 82071, and Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, Arizona 85287-1604.

Journal

Biomacromolecules. 2010 Jul 1. [Epub ahead of print]

Abstract

Major ampullate (dragline) spider silk is a coveted biopolymer due to its combination of strength and extensibility. The dragline silk of different spiders have distinct mechanical properties that can be qualitatively correlated to the protein sequence. This study uses amino acid analysis and carbon-13 solid-state NMR to compare the molecular composition, structure, and dynamics of major ampullate dragline silk of four orb-web spider species ( Nephila clavipes , Araneus gemmoides , Argiope aurantia , and Argiope argentata ) and one cobweb species ( Latrodectus hesperus ). The mobility of the protein backbone and amino acid side chains in water exposed silk fibers is shown to correlate to the proline content. This implies that regions of major ampullate spidroin 2 protein, which is the only dragline silk protein with any significant proline content, become significantly hydrated in dragline spider silk.

Citation

PMID: 20593757 [PubMed - as supplied by publisher]

 

Title

SnapShot: Silk biomaterials.

Authors

Omenetto FG, Kaplan DL.

 

Tufts University, Biomedical Engineering Department, Medford, MA 02155, USA.

Journal

Biomaterials. 2010 Aug;31(23):6119-20.

Abstract

http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=link&linkname=pubmed_pubmed&uid=20593549

Citation

PMID: 20593549 [PubMed - in process]

 

Title

Silk-Elastinlike Hydrogel Improves the Safety of Adenovirus-Mediated Gene-Directed Enzyme-Prodrug Therapy.

Authors

Gustafson JA, Price RA, Greish K, Cappello J, Ghandehari H.

Journal

Mol Pharm. 2010 Jun 29. [Epub ahead of print]

Abstract

Recombinant Silk-Elastinlike Protein polymers (SELPs) are well-known for their highly tunable properties on both the molecular and macroscopic hydrogel level. One specific structure of these polymers, SELP-815K, has been investigated as an injectable controlled delivery system for the treatment of head and neck cancer via a gene-directed enzyme prodrug therapy (GDEPT) approach. Due to its pore size and gelation properties in vivo, SELP restricts the distribution and controls the release of therapeutic viruses for up to one month. It has been shown that SELP-mediated delivery significantly improves therapeutic outcome of the herpes simplex virus thymidine kinase (HSVtk)/ganciclovir (GCV) system in xenograft models of human head and neck cancer. However little is known about potential benefits of this approach with regard to toxicity in the presence of a fully intact immune system. The studies presented here were designed to assess the change in toxicity of the SELP mediated viral delivery compared to free viral injection in a non-tumor bearing immune competent mouse model. Toxicity was assessed at 1, 2, 4, and 12 weeks via body weight monitoring, complete blood count (CBC), and blood chemistry. It was found that in the acute and subacute phases (weeks 1-4) there is significant toxicity in groups combining the virus and the prodrug, and matrix-mediated gene delivery with SELP demonstrates a reduction in toxicity from the 2 week time point through the 4 week time point. At the end of the subchronic phase (12 weeks), signs of toxicity had subsided in both groups. Based on these results, recombinant SELPs offer a significant reduction in toxicity of virus-mediated GDEPT treatment compared to free virus injection in the acute and subacute phases.

Citation

PMID: 20586469 [PubMed - as supplied by publisher]

 

Title

Surgical gloves.

Authors

Ellis H.

 

Department of Anatomy, University of London, Guy's Campus, London, SE1 1UL.

Journal

J Perioper Pract. 2010 Jun;20(6):219-20.

Abstract

Surgeons and obstetricians, over the centuries, were only too aware that accidental open injuries during their work, especially in a septic case, could lead to an infected wound, a fulminating illness and often death. Even before the bacterial nature of infection had been established in the mid-19th century, it was still obvious that this dangerous and often fatal condition was caused by the transfer of some poisonous material or 'miasma' from the patient to his surgeon. As long ago as 1758, an obstetrician named Walbaum protected his hands by covering them with sheep's caecum. Others used gloves of cotton, silk and leather. After Charles Goodyear developed the vulcanisation process to stabilise rubber in 1844, this became the material of choice for these rather crude protective gloves.

Citation

PMID: 20586363 [PubMed - in process]

 

Title

Influence of spider silk on refugia preferences of the recluse spiders Loxosceles reclusa and Loxosceles laeta (Araneae: Sicariidae).

Authors

Vetter RS, Rust MK.

 

Department of Entomology, University of California, Riverside, CA 92521, USA. rick.vetter@ucr.edu

Journal

J Econ Entomol. 2010 Jun;103(3):808-15.

Abstract

In a previous experimental study, recluse spiders Loxosceles reclusa Gertsch and Mulaik and Loxosceles laeta (Nicolet) (Araneae: Sicariidae) preferred small cardboard refugia covered with conspecific silk compared with never-occupied refugia. Herein, we investigated some factors that might be responsible for this preference using similar cardboard refugia. When the two Loxosceles species were given choices between refugia previously occupied by their own and by the congeneric species, neither showed a species-specific preference; however, each chose refugia coated with conspecific silk rather than those previously inhabited by a distantly related cribellate spider, Metaltella simoni (Keyserling). When L. laeta spiders were offered refugia that were freshly removed from silk donors compared with heated, aged refugia from the same silk donor, older refugia were preferred. Solvent extracts of L. laeta silk were chosen approximately as often as control refugia when a range of solvents (methylene chloride:methanol, water, and hexane) were used. However, when acetone was used on similar silk, there was a statistical preference for the control, indicating that there might be a mildly repellent aspect to acetone-washed silk. Considering the inability to show attraction to chemical aspects of fresh silk, it seems that physical attributes may be more important for selection and that there might be repellency to silk of a recently vacated spider. These findings are discussed in regard to pest management strategies to control recluse spiders.

Citation

PMID: 20568627 [PubMed - in process]

 

Title

Preliminary Evaluation of a Novel Strong/Osteoinduc tive Calcium Phosphate Cement.

Authors

Qu Y, Yang Y, Li J, Chen Z, Li J, Tang K, Man Y.

 

State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, China.

Journal

J Biomater Appl. 2010 Jun 21. [Epub ahead of print]

Abstract

We developed a novel calcium phosphate cement (CPC) by combining the silk fibroin and osteogenic supplements (beta-glycerophosphate, ascorbic acid, and dexamethasone) with alpha-tricalcium phosphate cement. Mesenchymal stem cells (MSCs) were cultured on the novel CPC scaffold. Results showed that the novel CPC scaffold was biocompatible and favorable for the adhesion, spreading, and proliferation of MSCs. Osteogenic differentiation of MSCs was confirmed by high osteocalcin content and elevated gene expressions of bone markers, such as alkaline phosphatase, collagen type I, and osteocalcin. Therefore, the novel CPC scaffold may be potentially useful for implant fixation and more rapid new bone formation in moderate load-bearing applications.

Citation

PMID: 20566653 [PubMed - as supplied by publisher]

 

Title

Silk Fibroin/Sodium Carboxymethylcellulose Blend ed Films for Biotechnological Applications.

Authors

Kundu J, Mohapatra R, Kundu SC.

Journal

J Biomater Sci Polym Ed. 2010 Jun 21. [Epub ahead of print]

Abstract

The potential of silk protein is increased because of its importance as natural biopolymer for biotechnological and biomedical applications. The main disadvantage of silk fibroin films is their high brittleness. Thus, we studied blends of fibroin with other polymers to improve the film properties. Considering the possible applications of films in biomedical applications, we used a natural and biodegradable polymer as the second component. This study reports the fabrication and characterization of mulberry silk protein fibroin and sodium carboxymethylcellulose (NaCMC) blended films as potential substrates for in vitro cell culture. The blended films are investigated of their chemical interactions, morphologies, thermal, mechanical properties in addition to its swelling properties and biocompatibility. The addition of NaCMC improves the elasticity of fibroin films and its thermal properties. The change of morphology, swelling behavior and increase of surface roughness of the films were also observed in the blended films. The films become insoluble on alcohol treatment and are stable for longer duration in hydrolytic medium. The blended films are cytocompatible and supported adhesion and growth of mouse fibroblast cells. The results suggest that NaCMC blended silk fibroin films are found to be potential substratum for supporting cell adhesion and proliferation.

Citation

PMID: 20566044 [PubMed - as supplied by publisher]

 

Title

Fiber formation of a synthetic spider peptide derived from Nephila clavata.

Authors

Hidaka Y, Kontani KI, Taniguchi R, Saiki M, Yokoi S, Yukuhiro K, Yamaguchi H, Miyazawa M.

 

Graduate school of Science and engineering, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 567-8502, Japan.

Journal

Biopolymers. 2010 May 26. [Epub ahead of print]

Abstract

Dragline silk is a high performance biopolymer with exceptional mechanical properties. Artificial spider dragline silk is currently prepared by a recombinant technique or chemical synthesis. However, the recombinant process is costly and large-sized synthetic peptides are needed for fiber formation. In addition, the silk fibers that are produced are much weaker than a fiber derived from a native spider. In this study, a small peptide was chemically synthesized and examined for its ability to participate in fiber formation. A short synthetic peptide derived from Nephila clavata was prepared by a solid phase peptide method, based on a prediction using the hydrophobic parameter of each individual amino acid residue. After purification of the spider peptide, fiber formation was examined under several conditions. Fiber formation proceeded in the acidic pH range and larger fibers were produced when organic solvents, such as trifluoroethanol and acetonitrile were used at an acidic pH. CD measurements of the spider peptide indicate that the peptide has a beta-sheet structure and that the formation of a beta-sheet structure is required for the spider peptide to undergo fiber formation. (c) 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2010.

Citation

PMID: 20564008 [PubMed - as supplied by publisher]

 

Title

The effect of sericin from various extraction methods on cell viability and collagen production. Free PMC Article

Authors

Aramwit P, Kanokpanont S, Nakpheng T, Srichana T.

 

Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand.

Journal

Int J Mol Sci. 2010 May 20;11(5):2200-11.

Abstract

Silk sericin (SS) can accelerate cell proliferation and attachment; however, SS can be extracted by various methods, which result in SS exhibiting different physical and biological properties. We found that SS produced from various extraction methods has different molecular weights, zeta potential, particle size and amino acid content. The MTT assay indicated that SS from all extraction methods had no toxicity to mouse fibroblast cells at concentrations up to 40 mug/mL after 24 h incubation, but SS obtained from some extraction methods can be toxic at higher concentrations. Heat-degraded SS was the least toxic to cells and activated the highest collagen production, while urea-extracted SS showed the lowest cell viability and collagen production. SS from urea extraction was severely harmful to cells at concentrations higher than 100 mug/mL. SS from all extraction methods could still promote collagen production in a concentration-dependent manner, even at high concentrations that are toxic to cells.

Citation

PMCID: PMC2885102,  PMID: 20559510 [PubMed - in process]

 

Title

Development of Small-Diameter Vascular Grafts Based on Silk Fibroin Fibers from Bombyx mori for Vascular Regeneration.

Authors

Nakazawa Y, Sato M, Takahashi R, Aytemiz D, Takabayashi C, Tamura T, Enomoto S, Sata M, Asakura T.

Journal

J Biomater Sci Polym Ed. 2010 Jun 16. [Epub ahead of print]

Abstract

In the field of surgical revascularization, the need for functional small-diameter (1.5-4.0 mm in diameter) vascular grafts is increasing. Several synthetic biomaterials have been tested for this purpose, but in many cases they cause thrombosis. In this study, we report the development of small-diameter vascular grafts made from silk fibroin fibers from the domestic silkworm Bombyx mori or recombinant silk fibroin fibers from a transgenic silkworm. The vascular grafts were prepared by braiding, flattening and winding the silk fibers twice onto a cylindrical polymer tube followed by coating with an aqueous silk fibroin solution. The grafts, which are 1.5 mm in inner diameter and 10 mm in length, were implanted into rat abdominal aorta. An excellent patency (ca. 85%, n=27) at 12 months after grafting with wild-type silk fibers was obtained. Endothelial cells and smooth muscle cells migrated into the silk fibroin graft early after implantation, and became organized into an endothelium and a media-like smooth muscle layer.

Citation

PMID: 20557695 [PubMed - as supplied by publisher]

 

Title

Relationships between degradability of silk scaffolds and osteogenesis.

Authors

Park SH, Gil ES, Kim HJ, Lee K, Kaplan DL.

 

Department of Biomedical Engineering, School of Engineering, Tufts University, 4 Colby St, Medford, MA 02155, USA.

Journal

Biomaterials. 2010 Aug;31(24):6162-72.

Abstract

Bone repairs represent a major focus in orthopedic medicine with biomaterials as a critical aspect of the regenerative process. However, only a limited set of biomaterials are utilized today and few studies relate biomaterial scaffold design to degradation rate and new bone formation. Matching biomaterial remodeling rate towards new bone formation is important in terms of the overall rate and quality of bone regeneration outcomes. We report on the osteogenesis and metabolism of human bone marrow derived mesenchymal stem cells (hMSCs) in 3D silk scaffolds. The scaffolds were prepared with two different degradation rates in order to study relationships between matrix degradation, cell metabolism and bone tissue formation in vitro. SEM, histology, chemical assays, real-time PCR and metabolic analyses were assessed to investigate these relationships. More extensively mineralized ECM formed in the scaffolds designed to degrade more rapidly, based on SEM, von Kossa and type I collagen staining and calcium content. Measures of osteogenic ECM were significantly higher in the more rapidly degrading scaffolds than in the more slowly degrading scaffolds over 56 days of study in vitro. Metabolic analysis, including glucose and lactate levels, confirmed the degradation rate differences with the two types of scaffolds, with the more rapidly degrading scaffolds supporting higher levels of glucose consumption and lactate synthesis by the hMSCs upon osteogenesis, in comparison to the more slowly degrading scaffolds. The results demonstrate that scaffold degradation rates directly impact the metabolism of hMSCs, and in turn the rate of osteogenesis. An understanding of the interplay between cellular metabolism and scaffold degradability should aid in the more rational design of scaffolds for bone regeneration needs both in vitro and in vivo.

Citation

PMCID: PMC2891356 [Available on 2011/8/1], PMID: 20546890 [PubMed - in process]

 

Title

Biomimetic calcium phosphate coatings on recombinant spider silk fibres.

Authors

Yang L, Hedhammar M, Blom T, Leifer K, Johansson J, Habibovic P, van Blitterswijk CA.

 

Department of Tissue Regeneration, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.

Journal

Biomed Mater. 2010 Jun 11;5(4):045002. [Epub ahead of print]

Abstract

Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently, artificial spider silk, with mechanical and structural characteristics similar to those of native spider silk, has been produced from recombinant minispidroins. In the present study, supersaturated simulated body fluid was used to deposit calcium phosphate coatings on recombinant spider silk fibres. The mineralization process was followed in time using scanning electron microscopy equipped with an energy dispersive x-ray (EDX) detector and Raman spectroscope. Focused ion beam technology was used to produce a cross section of a coated fibre, which was further analysed by EDX. Preliminary in vitro experiments using a culture of bone marrow-derived human mesenchymal stem cells (hMSCs) on coated fibres were also performed. This study showed that recombinant spider silk fibres were successfully coated with a homogeneous and thick crystalline calcium phosphate layer. In the course of the mineralization process from modified simulated body fluid, sodium chloride crystals were first deposited on the silk surface, followed by the deposition of a calcium phosphate layer. The coated silk fibres supported the attachment and growth of hMSCs.

Citation

PMID: 20539057 [PubMed - as supplied by publisher]

 

Title

Biocomposites Electrospun with Poly(epsilon-caprolactone) and Silk Fibroin Powder for Biomedical Applications.

Authors

Lee H, Kim G.

Journal

J Biomater Sci Polym Ed. 2010 Jun 9. [Epub ahead of print]

Abstract

Biomedical synthetic polymers have been used in soft and hard tissue regeneration because of their good processability and biodegradability. However, biomaterials such as poly(epsilon-caprolactone) (PCL) have various shortcomings, including intrinsic hydrophobicity and lack of bioactive functional groups. The material must be reinforced with natural biomaterials to achieve good cellular and mechanical performance as biomedical material. We fabricated a biocomposite using PCL and silk fibroin (SF) powder, which has good biocompatibility and mechanical properties. The hydrophilicity, mechanical properties and cellular behavior of the PCL/SF fibers were analyzed. In addition, we obtained a highly oriented conduit of electrospun biocomposite fibers by modifying the rolling collector of the electrospinning system. As the alignment of micro/nanofibers increased, the orthotropic mechanical properties were improved. The biocompatibility of the biocomposite was evaluated in a culture of bone-marrow-derived rat mesenchymal stem cells. The cellular result demonstrated the potential usefulness of electrospun biocomposites for various biomedical conduit systems.

Citation

PMID: 20537249 [PubMed - as supplied by publisher]

 

Title

In Vitro and In Vivo Release of Basic Fibroblast Growth Factor Using a Silk Fibroi n Scaffold as Delivery Carrier.

Authors

Wongpanit P, Ueda H, Tabata Y, Rujiravanit R.

Journal

J Biomater Sci Polym Ed. 2010 Jun 8. [Epub ahead of print]

Abstract

Two different solvents were used to prepare two types of silk fibroin scaffolds via the salt-leaching technique, i.e., hexafluoroisopropanol (HFIP) and water. The in vitro release study suggests that the opposite charge between the silk fibroin and basic fibroblast growth factor (bFGF) at physiological pH rendered them to form a complex, and the difference in the solvents used to produce the silk fibroin scaffold did not affect the affinity of silk fibroin to bFGF. However, a higher degradation rate of the aqueous-derived silk fibroin scaffolds provided faster in vitro release kinetics of the bFGF, as compared to the HFIP-derived scaffolds. From the in vivo studies, the use of silk fibroin scaffolds as the carrier matrix enabled the control of the in vivo release of bFGF in a sustained fashion over two weeks, while the majority of the bFGF disappeared within one day after the injection of the bFGF in soluble form. In addition, the in vivo release of bFGF from the silk fibroin scaffolds was not affected by the mode of processing due to their similar degradation behavior in vivo.

Citation

PMID: 20534193 [PubMed - as supplied by publisher]

 

Title

A conserved spider silk domain acts as a molecular switch that controls fibre assembly.

Authors

Hagn F, Eisoldt L, Hardy JG, Vendrely C, Coles M, Scheibel T, Kessler H.

 

Center for Integrated Protein Science (CIPSM), Technische Universität München, 85747 Garching, Germany.

Journal

Nature. 2010 May 13;465(7295):239-42.

Abstract

A huge variety of proteins are able to form fibrillar structures, especially at high protein concentrations. Hence, it is surprising that spider silk proteins can be stored in a soluble form at high concentrations and transformed into extremely stable fibres on demand. Silk proteins are reminiscent of amphiphilic block copolymers containing stretches of polyalanine and glycine-rich polar elements forming a repetitive core flanked by highly conserved non-repetitive amino-terminal and carboxy-terminal domains. The N-terminal domain comprises a secretion signal, but further functions remain unassigned. The C-terminal domain was implicated in the control of solubility and fibre formation initiated by changes in ionic composition and mechanical stimuli known to align the repetitive sequence elements and promote beta-sheet formation. However, despite recent structural data, little is known about this remarkable behaviour in molecular detail. Here we present the solution structure of the C-terminal domain of a spider dragline silk protein and provide evidence that the structural state of this domain is essential for controlled switching between the storage and assembly forms of silk proteins. In addition, the C-terminal domain also has a role in the alignment of secondary structural features formed by the repetitive elements in the backbone of spider silk proteins, which is known to be important for the mechanical properties of the fibre.

Citation

PMID: 20463741 [PubMed - indexed for MEDLINE]

 

Title

Self-assembly of spider silk proteins is controlled by a pH-sensitive relay.

Authors

Askarieh G, Hedhammar M, Nordling K, Saenz A, Casals C, Rising A, Johansson J, Knight SD.

 

Department of Chemistry, Oslo University, 1033 Blindern, 0315 Oslo, Norway.

Journal

Nature. 2010 May 13;465(7295):236-8.

Abstract

Nature's high-performance polymer, spider silk, consists of specific proteins, spidroins, with repetitive segments flanked by conserved non-repetitive domains. Spidroins are stored as a highly concentrated fluid dope. On silk formation, intermolecular interactions between repeat regions are established that provide strength and elasticity. How spiders manage to avoid premature spidroin aggregation before self-assembly is not yet established. A pH drop to 6.3 along the spider's spinning apparatus, altered salt composition and shear forces are believed to trigger the conversion to solid silk, but no molecular details are known. Miniature spidroins consisting of a few repetitive spidroin segments capped by the carboxy-terminal domain form metre-long silk-like fibres irrespective of pH. We discovered that incorporation of the amino-terminal domain of major ampullate spidroin 1 from the dragline of the nursery web spider Euprosthenops australis (NT) into mini-spidroins enables immediate, charge-dependent self-assembly at pH values around 6.3, but delays aggregation above pH 7. The X-ray structure of NT, determined to 1.7 A resolution, shows a homodimer of dipolar, antiparallel five-helix bundle subunits that lack homologues. The overall dimeric structure and observed charge distribution of NT is expected to be conserved through spider evolution and in all types of spidroins. Our results indicate a relay-like mechanism through which the N-terminal domain regulates spidroin assembly by inhibiting precocious aggregation during storage, and accelerating and directing self-assembly as the pH is lowered along the spider's silk extrusion duct.

Citation

PMID: 20463740 [PubMed - indexed for MEDLINE]

 

Title

Structure and gelation mechanism of silk hydrogels.

Authors

Nagarkar S, Nicolai T, Chassenieux C, Lele A.

 

Complex Fluids and Polymer Engineering Group, Polymer Science and Engineering Division, National Chemical Laboratory, India-411 008.

Journal

Phys Chem Chem Phys. 2010 Apr 21;12(15):3834-44. Epub 2010 Feb 24.

Abstract

Silk fibroin was regenerated from cocoons produced by the silkworm Bombyx Mori. Light scattering showed that an aqueous solution of the regenerated silk fibroin (RSF) was made of individual proteins with a weight average molar mass of about 4 x 10(5) g mol(-1) and a hydrodynamic radius of about 10 nm. Gel formation of RSF in acidic solutions was investigated as a function of the pH (2-4), concentration (0.5-10 g L(-1)) and temperature (5-70 degrees C). The structure of the gels was studied using light scattering and confocal laser scanning microscopy. The structure was found to be self-similar from length scales of less than 15 nm up to length scales of about 1 microm, and characterized by a correlation length of a few microns. Gel formation was tracked using turbidity, rheology, light scattering and circular dichroism. Gelation involves the formation of self-similar aggregates with a growth rate that increases exponentially. The protein aggregation is correlated to, and perhaps caused by, the formation of beta-sheets, the fraction of which also increases exponentially with time.

Citation

PMID: 20358077 [PubMed - indexed for MEDLINE]

 

Title

A facile fabrication strategy for patterning protein chain conformation in silk materials.

Authors

Gupta MK, Singamaneni S, McConney M, Drummy LF, Naik RR, Tsukruk VV.

 

School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.

Journal

Adv Mater. 2010 Jan 5;22(1):115-9.

Abstract

http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=link&linkname=pubmed_pubmed&uid=20217709

Citation

PMID: 20217709 [PubMed - indexed for MEDLINE]

 

Title

Bio-microfluidics: biomaterials and biomimetic designs.

Authors

Domachuk P, Tsioris K, Omenetto FG, Kaplan DL.

 

Department of Biomedical Engineering, Tufts University Medford, Massachusetts 02155, USA.

Journal

Adv Mater. 2010 Jan 12;22(2):249-60.

Abstract

Bio-microfluidics applies biomaterials and biologically inspired structural designs (biomimetics) to microfluidic devices. Microfluidics, the techniques for constraining fluids on the micrometer and sub-micrometer scale, offer applications ranging from lab-on-a-chip to optofluidics. Despite this wealth of applications, the design of typical microfluidic devices imparts relatively simple, laminar behavior on fluids and is realized using materials and techniques from silicon planar fabrication. On the other hand, highly complex microfluidic behavior is commonplace in nature, where fluids with nonlinear rheology flow through chaotic vasculature composed from a range of biopolymers. In this Review, the current state of bio-microfluidic materials, designs and applications are examined. Biopolymers enable bio-microfluidic devices with versatile functionalization chemistries, flexibility in fabrication, and biocompatibility in vitro and in vivo. Polymeric materials such as alginate, collagen, chitosan, and silk are being explored as bulk and film materials for bio-microfluidics. Hydrogels offer options for mechanically functional devices for microfluidic systems such as self-regulating valves, microlens arrays and drug release systems, vital for integrated bio-microfluidic devices. These devices including growth factor gradients to study cell responses, blood analysis, biomimetic capillary designs, and blood vessel tissue culture systems, as some recent examples of inroads in the field that should lead the way in a new generation of microfluidic devices for bio-related needs and applications. Perhaps one of the most intriguing directions for the future will be fully implantable microfluidic devices that will also integrate with existing vasculature and slowly degrade to fully recapitulate native tissue structure and function, yet serve critical interim functions, such as tissue maintenance, drug release, mechanical support, and cell delivery.

Citation

PMID: 20217686 [PubMed - indexed for MEDLINE]

 

Title

Identification of Ser2 proteins as major sericin components in the n on-cocoon silk of Bombyx mori.

Authors

Takasu Y, Hata T, Uchino K, Zhang Q.

 

National Institute of Agrobiological Sciences, Tsukuba, Japan.

Journal

Insect Biochem Mol Biol. 2010 Apr;40(4):339-44. Epub 2010 Mar 1.

Abstract

Sericins are glue proteins of Bombyx mori silk fibers. They are produced in the middle silk gland (MSG) cells, stored in the lumen, and pushed out from the spinneret surrounding the fibroin fibers. The Ser2 gene was partly cloned from the anterior region of the MSG more than 20 years ago and is regarded as a sericin-encoding gene; however, Ser2 proteins do not appear to be major components of cocoon proteins. We used northern blotting to analyze the expression of three sericin genes--Ser1, Ser2, and Ser3--in the MSG of third to fifth instar larvae, and measured the corresponding cDNA levels by competitive PCR. The results revealed that Ser2 gene expression dominated until the middle period of the fifth instar, while the expression of the other genes was mainly observed after the middle fifth instar. Protein analysis demonstrated that the two Ser2 proteins produced by alternative splicing were major coating proteins of larval silk threads spun during the growing stages. The molecular components of larval silk sericin were completely different from those of cocoon sericin, and the difference may be related to the functions of the two kinds of silk fibers. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Citation

PMID: 20197092 [PubMed - indexed for MEDLINE]

 

Title

Transgenic silkworms (Bombyx mori) produce recom binant spider dragline silk in cocoons.

Authors

Wen H, Lan X, Zhang Y, Zhao T, Wang Y, Kajiura Z, Nakagaki M.

 

Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan. wenhongxiu@gmail.com

Journal

Mol Biol Rep. 2010 Apr;37(4):1815-21. Epub 2009 Jul 25.

Abstract

Spider dragline silk is a unique fibrous protein with a combination of tensile strength and elasticity, but the isolation of large amounts of silk from spiders is not feasible. In this study, we generated germline-transgenic silkworms (Bombyx mori) that spun cocoons containing recombinant spider silk. A piggyBac-based transformation vector was constructed that carried spider dragline silk (MaSp1) cDNA driven by the sericin 1 promoter. Silkworm eggs were injected with the vector, producing transgenic silkworms displaying DsRed fluorescence in their eyes. Genotyping analysis confirmed the integration of the MaSp1 gene into the genome of the transgenic silkworms, and silk protein analysis revealed its expression and secretion in the cocoon. Compared with wild-type silk, the recombinant silk displayed a higher tensile strength and elasticity. The results indicate the potential for producing recombinant spider silk in transgenic B. mori.

Citation

PMID: 19633923 [PubMed - indexed for MEDLINE]

 

Title

The Molecular Mechanism of Spider-Silk Formation.

Authors

Silvers R, Buhr F, Schwalbe H.

 

Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, 60438 Frankfurt (Germany), Fax: (+49) 69-798-29515.

Journal

Angew Chem Int Ed Engl. 2010 Jun 28. [Epub ahead of print]

Abstract

http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=link&linkname=pubmed_pubmed&uid=20586091

Citation

PMID: 20586091 [PubMed - as supplied by publisher]

 

Title

Microscopic structural analysis of fractured silk fibers from Bombyx mori and Samia cynthia ricini using (13) C CP/MAS NMR with a 1mm microcoil MAS NMR probehead.

Authors

Yamauchi K, Yamasaki S, Takahashi R, Asakura T.

 

Department of Biotechnology, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei-shi, Tokyo 184-8588, Japan.

Journal

Solid State Nucl Magn Reson. 2010 Jun 12. [Epub ahead of print]

Abstract

Conformational changes have been studied in silk fibers from the domestic silkworm Bombyx mori and a wild silkworm Samia cynthia ricini as a result of fractured by stretching. About 300 samples consisting of only the fractured regions of [1-(13)C]Ala or [1-(13)C]Gly labeled silk fibers were collected and observed by (13)C CP/MAS NMR spectra. The total amount of these fractured fibers is only about 1mg and therefore we used a home-built 1mm microcoil MAS NMR probehead. A very small increase in the fraction of random coil was noted for the alanine regions of both silk fibroins and for the glycine region of B. mori silk fibroin. However, there is no difference in the spectra before and after fractured for the glycine region of S. c. ricini silk fibroin. Thus, the influence of fracture occurs exclusively at the Ala region for S. c. ricini. The relationship between sequence, fracture and structure is discussed. Copyright © 2010 Elsevier Inc. All rights reserved.

Citation

PMID: 20579856 [PubMed - as supplied by publisher]

 

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