The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Craig Vierra - One of the best experts on this subject based on the ideXlab platform.

  • Advances in understanding the properties of spider silk
    Advances in Silk Science and Technology, 2020
    Co-Authors: T. Chuang, Yang Hsia, T. Pham, C. Ho, E. Blasingame, Craig Vierra
    Abstract:

    Abstract Spider silk has remarkable mechanical properties that rival many man-made materials, including nylon, Kevlar®, and high-tensile steel. Over the past three decades, scientists have been unraveling its mysterious, unique chemical and physical properties. Much insight into spider silk molecular structure has been driven by technological advances in biochemistry, molecular and structural biology, engineering, and physics. To comprehend its superior qualities and wide range of opportunities for industrial applications, we will review the diversity and chemical composition of different fiber types as well as the biofactories or silk-producing glands that manufacture fibers. We will place an emphasis on highlighting spider silk protein sequences and their relationship to structure and functions and compare the mechanical properties of fibers spun from two different species, specifically the cob weaver black widow spider, Latrodectus hesperus, and the golden orb weaver, Nephila clavipes. We will also explain the challenging nature of spider silk farming, which has resulted in the pursuit of recombinant DNA methodologies to clone spider silk genes for expression in transgenic organisms. Lastly, we will discuss the long-term goal of the scientific community, which includes the expression and purification of vast amounts of recombinant silk proteins as well as development of a spinning methodology to produce synthetic silks for endless applications. These include using the silk proteins and spun fibers for medicine, engineering, athletics, and defense.

  • Conserved C-terminal domain of spider tubuliform spidroin 1 contributes to extensibility in synthetic fibers.
    Biomacromolecules, 2012
    Co-Authors: Eric Gnesa, Yang Hsia, Jeffery L Yarger, Warner S. Weber, Joan Lin-cereghino, Geoff P. Lin-cereghino, Simon Y. Tang, Kimiko Agari, Craig Vierra
    Abstract:

    Spider silk is renowned for its extraordinary mechanical properties, having a balance of high tensile strength and extensibility. To date, the majority of studies have focused on the production of dragline silks from synthetic spider silk gene products. Here we report the first mechanical analysis of synthetic egg case silk fibers spun from the Latrodectus hesperus tubuliform silk proteins, TuSp1 and ECP-2. We provide evidence that recombinant ECP-2 proteins can be spun into fibers that display mechanical properties similar to other synthetic spider silks. We also demonstrate that silks spun from recombinant thioredoxin-TuSp1 fusion proteins that contain the conserved C-terminal domain exhibit increased extensibility and toughness when compared to the identical fibers spun from fusion proteins lacking the C-terminus. Mechanical analyses reveal that the properties of synthetic tubuliform silks can be modulated by altering the postspin draw ratios of the fibers. Fibers subject to increased draw ratios showe...

  • spider minor ampullate silk proteins are constituents of prey wrapping silk in the cob weaver Latrodectus hesperus
    Biochemistry, 2008
    Co-Authors: Coby La Mattina, Ryan Reza, Xiaoyi Hu, Arnold M Falick, Keshav Vasanthavada, Shannon Mcnary, Craig Vierra
    Abstract:

    Spiders spin high performance fibers with diverse biological functions and mechanical properties. Molecular and biochemical studies of spider prey wrapping silks have revealed the presence of the aciniform silk fibroin AcSp1-like. In our studies we demonstrate the presence of a second distinct polypeptide present within prey wrapping silk. Combining matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometry and reverse genetics, we have isolated a novel gene called MiSp1-like and demonstrate that its protein product is a constituent of prey wrap silks from the black widow spider, Latrodectus hesperus. BLAST searches of the NCBInr protein database using the amino acid sequence of MiSp1-like revealed similarity to the conserved C-terminal domain of silk family members. In particular, MiSp1-like showed the highest degree of sequence similarity to the nonrepetitive C-termini of published orb-weaver minor ampullate fibroin molecules. Analysis of the internal amino acid sequence of the ...

  • aciniform spidroin a constituent of egg case sacs and wrapping silk fibers from the black widow spider Latrodectus hesperus
    Journal of Biological Chemistry, 2007
    Co-Authors: Keshav Vasanthavada, Anne M F Moore, Coby La Mattina, Ryan Reza, Xiaoyi Hu, Arnold M Falick, Patrick R Jones, Tiffany Tuton, Craig Vierra
    Abstract:

    Abstract Spiders produce high performance fibers with diverse mechanical properties and biological functions. Molecular and biochemical studies of spider egg case silk have revealed that the main constituent of the large diameter fiber contains the fibroin TuSp1. Here we demonstrate by SDS-PAGE and protein silver staining the presence of a distinct ∼300-kDa polypeptide that is found in solubilized egg case sacs. Combining matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometry and reverse genetics, we have isolated a novel gene called AcSp1-like and demonstrate that its protein product is assembled into the small diameter fibers of egg case sacs and wrapping silks from the black widow spider, Latrodectus hesperus. BLAST searches of the NCBInr protein data base using the amino acid sequence of AcSp1-like revealed similarity to AcSp1, an inferred protein proposed to be a component of wrapping silk. However, the AcSp1-like protein was found to display more nonuniformity in its internal iterated repeat modules than the putative AcSp1 fibroin. Real time quantitative PCR analysis demonstrates that the AcSp1-like gene displays an aciniform gland-restricted pattern of expression. The amino acid composition of the fibroins extracted from the luminal contents of the aciniform glands was remarkably similar to the predicted amino acid composition of the AcSp1-like protein, which supports the assertion that AcSp1-like protein represents the major constituent stored within the aciniform gland. Collectively, our findings provide the first direct molecular evidence for the involvement of the aciniform gland in the production of a common fibroin that is assembled into the small diameter threads of egg case and wrapping silk of cob weavers.

  • analysis of aqueous glue coating proteins on the silk fibers of the cob weaver Latrodectus hesperus
    Biochemistry, 2007
    Co-Authors: Xiaoyi Hu, Coby La Mattina, Arnold M Falick, Keshav Vasanthavada, Patrick R Jones, Jing Yuan, Xiaodong Wang, Craig Vierra
    Abstract:

    : Elucidation of the molecular composition and physical properties of spider glue is necessary to understand its function in the mechanics of the web and prey capture. Previous reports have indicated that components of the adhesive coating contain inorganic molecules, phosphorylated glycoproteins, lipids, and organic low-molecular mass (LMM) compounds. Using a proteomic strategy, we have investigated the viscid, aqueous components that coat different silk fiber types from the black widow spider, Latrodectus hesperus. After in-solution tryptic digestion of the aqueous protein material extracted from egg case sacs, gumfooted lines, and the web scaffolding connection joints, followed by peptide analysis using MALDI tandem TOF mass spectrometry, we demonstrate that these fibers are coated with common peptides. Utilizing a reverse genetics approach, we have isolated the cDNAs encoding two distinct fiber coating products, which we have named spider coating peptide 1 and 2 (SCP-1 and SCP-2). Secreted forms of SCP-1 and SCP-2 contain 36 and 19 amino acids, respectively, and their primary sequences display no significant similarities to ensemble repeat units from traditional fibroins. Quantitative real-time reverse transcription PCR analyses show that these mRNAs are chiefly produced by the aggregate gland. Biochemical studies also demonstrate that the SCP-1 peptide has intrinsic metal binding properties, suggesting a role of peptide-metal ion interactions with the fiber constituents to enhance thread performance. Collectively, these investigations are the first to reveal a novel role for the aggregate gland in the production of peptides that coat spider silk threads.

Cheryl Y Hayashi - One of the best experts on this subject based on the ideXlab platform.

  • Quasistatic and continuous dynamic characterization of the mechanical properties of silk from the cobweb of the black widow spider Latrodectus hesperus.
    The Journal of experimental biology, 2020
    Co-Authors: Todd A Blackledge, John E Swindeman, Cheryl Y Hayashi
    Abstract:

    Spider silks are among the strongest and toughest known materials, but investigation of these remarkable properties has been confined largely to orb-weaving spiders. We investigated the mechanical performance of silk from the cobweb-weaving spider Latrodectus hesperus. Both silk from the scaffolding region of the web and sticky gumfooted capture lines had material properties similar to the major ampullate silk that orb weavers use as the framework for their orb webs. Major ampullate fibers obtained from anaesthetized Latrodectus spiders were similar, but exhibited increased stiffness and reduced extensibility. Novel continuous dynamic analysis of the silks revealed that the loss tangent (tandelta) increased rapidly during the first 2-3% of extension and reached a maximum near the yield point of fibers. The loss tangent then rapidly declined at an ever-decreasing rate until failure. We suggest that these data support molecular models for the mechanics of spider silk. We also demonstrate that the addition of sticky aggregate glue to the ends of the gumfooted lines modulates their mechanical performance--reducing stiffness and increasing extensibility. The storage modulus of viscid regions of the gumfooted lines was much lower than dry regions. This may be explained by disruption of hydrogen bonding within the amorphous regions of the fibers due to hydration from the glue.

  • dissection of silk glands in the western black widow Latrodectus hesperus
    Journal of Arachnology, 2018
    Co-Authors: Cheryl Y Hayashi, Crystal R Chaw
    Abstract:

    The silk glands of the Western black widow Latrodectus hesperus Chamberlin & Ivie, 1935 are morphologically and functionally distinct. Studies of spider silk glands often show only high magnification images of sections or drawings of glands, making differentiation of dissected glands difficult. We dissect all of the gland types from L. hesperus females and show their gross morphology with light microscopy. Our micrographs portray the distinct morphologies and relative sizes of each silk gland type, consistent with prior descriptions of the silk apparatus of Latrodectus spiders. Notably, we verify the presence of two differentiated pairs of aggregate silk glands and spigots, thus resolving a discrepancy in the literature.

  • Silk gene expression of theridiid spiders: implications for male-specific silk use
    Zoology, 2017
    Co-Authors: Sandra M. Correa-garhwal, Thomas H. Clarke, Nadia A Ayoub, R. Crystal Chaw, Cheryl Y Hayashi
    Abstract:

    Abstract Spiders (order Araneae) rely on their silks for essential tasks, such as dispersal, prey capture, and reproduction. Spider silks are largely composed of spidroins, members of a protein family that are synthesized in silk glands. As needed, silk stored in silk glands is extruded through spigots on the spinnerets. Nearly all studies of spider silks have been conducted on females; thus, little is known about male silk biology. To shed light on silk use by males, we compared silk gene expression profiles of mature males to those of females from three cob-web weaving species (Theridiidae). We de novo assembled species-specific male transcriptomes from Latrodectus hesperus , Latrodectus geometricus , and Steatoda grossa followed by differential gene expression analyses. Consistent with their complement of silk spigots, male theridiid spiders express appreciable amounts of aciniform, major ampullate, minor ampullate, and pyriform spidroin genes but not tubuliform spidroin genes. The relative expression levels of particular spidroin genes varied between sexes and species. Because mature males desert their prey-capture webs and become cursorial in their search for mates, we anticipated that major ampullate (dragline) spidroin genes would be the silk genes most highly expressed by males. Indeed, major ampullate spidroin genes had the highest expression in S. grossa males. However, minor ampullate spidroin genes were the most highly expressed spidroin genes in L. geometricus and L. hesperus males. Our expression profiling results suggest species-specific adaptive divergence of silk use by male theridiids.

  • Evidence from Multiple Species that Spider Silk Glue Component ASG2 is a Spidroin
    Scientific Reports, 2016
    Co-Authors: Matthew A. Collin, Thomas H. Clarke, Nadia A Ayoub, Cheryl Y Hayashi
    Abstract:

    Spiders in the superfamily Araneoidea produce viscous glue from aggregate silk glands. Aggregate glue coats prey-capture threads and hampers the escape of prey from webs, thereby increasing the foraging success of spiders. cDNAs for Aggregate Spider Glue 1 (ASG1) and 2 (ASG2) have been previously described from the golden orb-weaver, Nephila clavipes and Western black widow, Latrodectus hesperus . To further investigate aggregate glues, we assembled ASG1 and ASG2 from genomic target capture libraries constructed from three species of cob-web weavers and three species of orb-web weavers, all araneoids. We show that ASG1 is unlikely to be a glue, but rather is part of a widespread arthropod gene family, the peritrophic matrix proteins. For ASG2, we demonstrate its remarkable architectural and sequence similarities to spider silk fibroins, indicating that ASG2 is a member of the spidroin gene family. Thus, spidroins have diversified into glues in addition to task-specific, high performance fibers.

  • Proteomic Evidence for Components of Spider Silk Synthesis from Black Widow Silk Glands and Fibers.
    Journal of Proteome Research, 2015
    Co-Authors: R. C. Chaw, Thomas H. Clarke, Nadia A Ayoub, Sandra M. Correa-garhwal, Cheryl Y Hayashi
    Abstract:

    Spider silk research has largely focused on spidroins, proteins that are the primary components of spider silk fibers. Although a number of spidroins have been characterized, other types of proteins associated with silk synthesis are virtually unknown. Previous analyses of tissue-specific RNA-seq libraries identified 647 predicted genes that were differentially expressed in silk glands of the Western black widow, Latrodectus hesperus. Only ∼5% of these silk-gland specific transcripts (SSTs) encode spidroins; although the remaining predicted genes presumably encode other proteins associated with silk production, this is mostly unverified. Here, we used proteomic analysis of multiple silk glands and dragline silk fiber to investigate the translation of the differentially expressed genes. We find 48 proteins encoded by the differentially expressed transcripts in L. hesperus major ampullate, minor ampullate, and tubuliform silk glands and detect 17 SST encoded proteins in major ampullate silk fibers. The obse...

Nadia A Ayoub - One of the best experts on this subject based on the ideXlab platform.

  • Ovarian Transcriptomic Analyses in the Urban Human Health Pest, the Western Black Widow Spider.
    Genes, 2020
    Co-Authors: Lindsay S Miles, Nadia A Ayoub, Robert A. Haney, Jessica E. Garb, Brian C. Verrelli
    Abstract:

    Due to their abundance and ability to invade diverse environments, many arthropods have become pests of economic and health concern, especially in urban areas. Transcriptomic analyses of arthropod ovaries have provided insight into life history variation and fecundity, yet there are few studies in spiders despite their diversity within arthropods. Here, we generated a de novo ovarian transcriptome from 10 individuals of the western black widow spider (Latrodectus hesperus), a human health pest of high abundance in urban areas, to conduct comparative ovarian transcriptomic analyses. Biological processes enriched for metabolism—specifically purine, and thiamine metabolic pathways linked to oocyte development—were significantly abundant in L. hesperus. Functional and pathway annotations revealed overlap among diverse arachnid ovarian transcriptomes for highly-conserved genes and those linked to fecundity, such as oocyte maturation in vitellogenin and vitelline membrane outer layer proteins, hormones, and hormone receptors required for ovary development, and regulation of fertility-related genes. Comparative studies across arachnids are greatly needed to understand the evolutionary similarities of the spider ovary, and here, the identification of ovarian proteins in L. hesperus provides potential for understanding how increased fecundity is linked to the success of this urban pest.

  • Silk gene expression of theridiid spiders: implications for male-specific silk use
    Zoology, 2017
    Co-Authors: Sandra M. Correa-garhwal, Thomas H. Clarke, Nadia A Ayoub, R. Crystal Chaw, Cheryl Y Hayashi
    Abstract:

    Abstract Spiders (order Araneae) rely on their silks for essential tasks, such as dispersal, prey capture, and reproduction. Spider silks are largely composed of spidroins, members of a protein family that are synthesized in silk glands. As needed, silk stored in silk glands is extruded through spigots on the spinnerets. Nearly all studies of spider silks have been conducted on females; thus, little is known about male silk biology. To shed light on silk use by males, we compared silk gene expression profiles of mature males to those of females from three cob-web weaving species (Theridiidae). We de novo assembled species-specific male transcriptomes from Latrodectus hesperus , Latrodectus geometricus , and Steatoda grossa followed by differential gene expression analyses. Consistent with their complement of silk spigots, male theridiid spiders express appreciable amounts of aciniform, major ampullate, minor ampullate, and pyriform spidroin genes but not tubuliform spidroin genes. The relative expression levels of particular spidroin genes varied between sexes and species. Because mature males desert their prey-capture webs and become cursorial in their search for mates, we anticipated that major ampullate (dragline) spidroin genes would be the silk genes most highly expressed by males. Indeed, major ampullate spidroin genes had the highest expression in S. grossa males. However, minor ampullate spidroin genes were the most highly expressed spidroin genes in L. geometricus and L. hesperus males. Our expression profiling results suggest species-specific adaptive divergence of silk use by male theridiids.

  • Evidence from Multiple Species that Spider Silk Glue Component ASG2 is a Spidroin
    Scientific Reports, 2016
    Co-Authors: Matthew A. Collin, Thomas H. Clarke, Nadia A Ayoub, Cheryl Y Hayashi
    Abstract:

    Spiders in the superfamily Araneoidea produce viscous glue from aggregate silk glands. Aggregate glue coats prey-capture threads and hampers the escape of prey from webs, thereby increasing the foraging success of spiders. cDNAs for Aggregate Spider Glue 1 (ASG1) and 2 (ASG2) have been previously described from the golden orb-weaver, Nephila clavipes and Western black widow, Latrodectus hesperus . To further investigate aggregate glues, we assembled ASG1 and ASG2 from genomic target capture libraries constructed from three species of cob-web weavers and three species of orb-web weavers, all araneoids. We show that ASG1 is unlikely to be a glue, but rather is part of a widespread arthropod gene family, the peritrophic matrix proteins. For ASG2, we demonstrate its remarkable architectural and sequence similarities to spider silk fibroins, indicating that ASG2 is a member of the spidroin gene family. Thus, spidroins have diversified into glues in addition to task-specific, high performance fibers.

  • Proteomic Evidence for Components of Spider Silk Synthesis from Black Widow Silk Glands and Fibers.
    Journal of Proteome Research, 2015
    Co-Authors: R. C. Chaw, Thomas H. Clarke, Nadia A Ayoub, Sandra M. Correa-garhwal, Cheryl Y Hayashi
    Abstract:

    Spider silk research has largely focused on spidroins, proteins that are the primary components of spider silk fibers. Although a number of spidroins have been characterized, other types of proteins associated with silk synthesis are virtually unknown. Previous analyses of tissue-specific RNA-seq libraries identified 647 predicted genes that were differentially expressed in silk glands of the Western black widow, Latrodectus hesperus. Only ∼5% of these silk-gland specific transcripts (SSTs) encode spidroins; although the remaining predicted genes presumably encode other proteins associated with silk production, this is mostly unverified. Here, we used proteomic analysis of multiple silk glands and dragline silk fiber to investigate the translation of the differentially expressed genes. We find 48 proteins encoded by the differentially expressed transcripts in L. hesperus major ampullate, minor ampullate, and tubuliform silk glands and detect 17 SST encoded proteins in major ampullate silk fibers. The obse...

  • Gene structure, regulatory control, and evolution of black widow venom latrotoxins
    FEBS Letters, 2014
    Co-Authors: Kanaka Varun Bhere, Nadia A Ayoub, Robert A. Haney, Jessica E. Garb
    Abstract:

    Black widow venom contains α-latrotoxin, infamous for causing intense pain. Combining 33 kb of Latrodectus hesperus genomic DNA with RNA-Seq, we characterized the α-latrotoxin gene and discovered a paralog, 4.5 kb downstream. Both paralogs exhibit venom gland specific transcription, and may be regulated post-transcriptionally via musashi-like proteins. A 4 kb intron interrupts the α-latrotoxin coding sequence, while a 10 kb intron in the 3′ UTR of the paralog may cause non-sense-mediated decay. Phylogenetic analysis confirms these divergent latrotoxins diversified through recent tandem gene duplications. Thus, latrotoxin genes have more complex structures, regulatory controls, and sequence diversity than previously proposed.

Jessica E. Garb - One of the best experts on this subject based on the ideXlab platform.

  • Ovarian Transcriptomic Analyses in the Urban Human Health Pest, the Western Black Widow Spider.
    Genes, 2020
    Co-Authors: Lindsay S Miles, Nadia A Ayoub, Robert A. Haney, Jessica E. Garb, Brian C. Verrelli
    Abstract:

    Due to their abundance and ability to invade diverse environments, many arthropods have become pests of economic and health concern, especially in urban areas. Transcriptomic analyses of arthropod ovaries have provided insight into life history variation and fecundity, yet there are few studies in spiders despite their diversity within arthropods. Here, we generated a de novo ovarian transcriptome from 10 individuals of the western black widow spider (Latrodectus hesperus), a human health pest of high abundance in urban areas, to conduct comparative ovarian transcriptomic analyses. Biological processes enriched for metabolism—specifically purine, and thiamine metabolic pathways linked to oocyte development—were significantly abundant in L. hesperus. Functional and pathway annotations revealed overlap among diverse arachnid ovarian transcriptomes for highly-conserved genes and those linked to fecundity, such as oocyte maturation in vitellogenin and vitelline membrane outer layer proteins, hormones, and hormone receptors required for ovary development, and regulation of fertility-related genes. Comparative studies across arachnids are greatly needed to understand the evolutionary similarities of the spider ovary, and here, the identification of ovarian proteins in L. hesperus provides potential for understanding how increased fecundity is linked to the success of this urban pest.

  • Extraction of venom and venom gland microdissections from spiders for proteomic and transcriptomic analyses.
    Journal of Visualized Experiments, 2014
    Co-Authors: Jessica E. Garb
    Abstract:

    Venoms are chemically complex secretions typically comprising numerous proteins and peptides with varied physiological activities. Functional characterization of venom proteins has important biomedical applications, including the identification of drug leads or probes for cellular receptors. Spiders are the most species rich clade of venomous organisms, but the venoms of only a few species are well-understood, in part due to the difficulty associated with collecting minute quantities of venom from small animals. This paper presents a protocol for the collection of venom from spiders using electrical stimulation, demonstrating the procedure on the Western black widow (Latrodectus hesperus). The collected venom is useful for varied downstream analyses including direct protein identification via mass spectrometry, functional assays, and stimulation of venom gene expression for transcriptomic studies. This technique has the advantage over protocols that isolate venom from whole gland homogenates, which do not separate genuine venom components from cellular proteins that are not secreted as part of the venom. Representative results demonstrate the detection of known venom peptides from the collected sample using mass spectrometry. The venom collection procedure is followed by a protocol for dissecting spider venom glands, with results demonstrating that this leads to the characterization of venom-expressed proteins and peptides at the sequence level.

  • Gene structure, regulatory control, and evolution of black widow venom latrotoxins
    FEBS Letters, 2014
    Co-Authors: Kanaka Varun Bhere, Nadia A Ayoub, Robert A. Haney, Jessica E. Garb
    Abstract:

    Black widow venom contains α-latrotoxin, infamous for causing intense pain. Combining 33 kb of Latrodectus hesperus genomic DNA with RNA-Seq, we characterized the α-latrotoxin gene and discovered a paralog, 4.5 kb downstream. Both paralogs exhibit venom gland specific transcription, and may be regulated post-transcriptionally via musashi-like proteins. A 4 kb intron interrupts the α-latrotoxin coding sequence, while a 10 kb intron in the 3′ UTR of the paralog may cause non-sense-mediated decay. Phylogenetic analysis confirms these divergent latrotoxins diversified through recent tandem gene duplications. Thus, latrotoxin genes have more complex structures, regulatory controls, and sequence diversity than previously proposed.

  • Dramatic expansion of the black widow toxin arsenal uncovered by multi-tissue transcriptomics and venom proteomics
    BMC Genomics, 2014
    Co-Authors: Robert A. Haney, Cheryl Y Hayashi, Nadia A Ayoub, Thomas H. Clarke, Jessica E. Garb
    Abstract:

    Background Animal venoms attract enormous interest given their potential for pharmacological discovery and understanding the evolution of natural chemistries. Next-generation transcriptomics and proteomics provide unparalleled, but underexploited, capabilities for venom characterization. We combined multi-tissue RNA-Seq with mass spectrometry and bioinformatic analyses to determine venom gland specific transcripts and venom proteins from the Western black widow spider (Latrodectus hesperus) and investigated their evolution.

  • multi tissue transcriptomics of the black widow spider reveals expansions co options and functional processes of the silk gland gene toolkit
    BMC Genomics, 2014
    Co-Authors: Thomas H. Clarke, Cheryl Y Hayashi, Robert A. Haney, Jessica E. Garb, Alex K Lancaster, Susan Corbett, Nadia A Ayoub
    Abstract:

    Background: Spiders (Order Araneae) are essential predators in every terrestrial ecosystem largely because they have evolved potent arsenals of silk and venom. Spider silks are high performance materials made almost entirely of proteins, and thus represent an ideal system for investigating genome level evolution of novel protein functions. However, genomic level resources remain limited for spiders. Results: We de novo assembled a transcriptome for the Western black widow (Latrodectus hesperus) from deeply sequenced cDNAs of three tissue types. Our multi-tissue assembly contained ~100,000 unique transcripts, of which > 27,000 were annotated by homology. Comparing transcript abundance among the different tissues, we identified 647 silk gland-specific transcripts, including the few known silk fiber components (e.g. six spider fibroins, spidroins). Silk gland specific transcripts are enriched compared to the entire transcriptome in several functions, including protein degradation, inhibition of protein degradation, and oxidation-reduction. Phylogenetic analyses of 37 gene families containing silk gland specific transcripts demonstrated novel gene expansions within silk glands, and multiple co-options of silk specific expression from paralogs expressed in other tissues. Conclusions: We propose a transcriptional program for the silk glands that involves regulating gland specific synthesis of silk fiber and glue components followed by protecting and processing these components into functional fibers and glues. Our black widow silk gland gene repertoire provides extensive expansion of resources for biomimetic applications of silk in industry and medicine. Furthermore, our multi-tissue transcriptome facilitates evolutionary analysis of arachnid genomes and adaptive protein systems.

Jeffery L Yarger - One of the best experts on this subject based on the ideXlab platform.

  • Insights into the Hierarchical Structure of Spider Dragline Silk Fibers: Evidence for Fractal Clustering of $\beta$-Sheet Nano-Crystallites
    arXiv: Materials Science, 2015
    Co-Authors: Chris J. Benmore, Warner S. Weber, Jeffery L Yarger
    Abstract:

    Spider dragline silk is one of the toughest materials known and understanding the hierarchical structure is a critical component in the efforts to connect structure to function. In this paper, we take the first step in elucidating the hierarchical fractal structure of $\beta$-sheet nano-crystallites, which form a robust self-similar network exhibiting an non-linear mechanical property. A combined small angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) study of the nano-crystalline component in dragline silk fibers from several species of spiders including, Latrodectus hesperus, Nephila clavipes, Argiope aurantia and Araneus gemmoides is presented. SAXS structure factors exhibit a `lamellar peak' in the q-range from 0.60 to 0.82 nm$^{-1}$ for various spider dragline silk fibers, indicating the presence of strong nano-crystal ordering on the $>$10 nm length-scale. The stochastically reconstructed electron density maps indicate that the $\beta$-sheet crystals are hierarchically structured as mass fractals and that nano-crystals tend to form 10 to 50 nm sized clusters with long-range crystalline ordering. This nano-crystal ordering along the fiber axis also helps to explain the difference between axial and radial sound velocities recently measured by Brillouin spectroscopy.

  • characterizing the secondary protein structure of black widow dragline silk using solid state nmr and x ray diffraction
    Biomacromolecules, 2013
    Co-Authors: Janelle E Jenkins, Gregory P. Holland, Sujatha Sampath, Emily Butler, Robert Henning, Jeffery L Yarger
    Abstract:

    This study provides a detailed secondary structural characterization of major ampullate dragline silk from Latrodectus hesperus (black widow) spiders. X-ray diffraction results show that the structure of black widow major ampullate silk fibers is comprised of stacked β-sheet nanocrystallites oriented parallel to the fiber axis and an amorphous region with oriented (anisotropic) and isotropic components. The combination of two-dimensional (2D) 13C–13C through-space and through-bond solid-state NMR experiments provide chemical shifts that are used to determine detailed information about the amino acid motif secondary structure in black widow spider dragline silk. Individual amino acids are incorporated into different repetitive motifs that make up the majority of this protein-based biopolymer. From the solid-state NMR measurements, we assign distinct secondary conformations to each repetitive amino acid motif and, hence, to the amino acids that make up the motifs. Specifically, alanine is incorporated in β-...

  • Non-invasive determination of the complete elastic moduli of spider silks
    Nature Materials, 2013
    Co-Authors: Kristie J Koski, Paul Akhenblit, Keri Mckiernan, Jeffery L Yarger
    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. The mechanical properties of a spider’s web are spatially mapped using Brillouin light scattering. This non-contact approach can probe the elastic properties of single fibres, intersection points and glue spots within the web, as well as measure how the elastic stiffness changes in supercontracted silk fibres.

  • Non-invasive determination of the complete elastic moduli of spider silks
    Nature Materials, 2013
    Co-Authors: Kristie J Koski, Paul Akhenblit, Keri Mckiernan, Jeffery L Yarger
    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.

  • total x ray scattering of spider dragline silk
    Physical Review Letters, 2012
    Co-Authors: C J Benmore, Thomas Izdebski, Jeffery L Yarger
    Abstract:

    Total x-ray scattering measurements of spider dragline silk fibers from Nephila clavipes, Argiope aurantia, and Latrodectus hesperus all yield similar structure factors, with only small variations between the different species. Wide-angle x-ray scattering from fibers orientated perpendicular to the beam shows a high degree of anisotropy, and differential pair distribution functions obtained by integrating over wedges of the equatorial and meridian planes indicate that, on average, the majority (95%) of the atom-atom correlations do not extend beyond 1 nm. Futhermore, the atom-atom correlations between 1 and 3 nm are not associated with the most intense diffraction peaks at Q ¼ 1‐2 � A � 1 . Disordered molecular orientations along the fiber axis are consistent with proteins in similar structural arrangements to those in the equatorial plane, which may be associated with the silk’s greater flexibility in this direction.