Journal of Structural Biology

ScienceDirect RSS
  • Crystal structures of S-adenosylhomocysteine hydrolase from the thermophilic bacterium Thermotoga maritima
    [Apr 2015]

    Publication date: Available online 17 March 2015
    Source:Journal of Structural Biology

    Author(s): Yingying Zheng , Chun-Chi Chen , Tzu-Ping Ko , Xiansha Xiao , Yunyun Yang , Chun-Hsiang Huang , Guojun Qian , Weilan Shao , Rey-Ting Guo

    S-adenosylhomocysteine (SAH) hydrolase catalyzes the reversible hydrolysis of SAH into adenosine and homocysteine by using NAD+ as a cofactor. The enzyme from Thermotoga maritima (tmSAHH) has great potentials in industrial applications because of its hyperthermophilic properties. Here, two crystal structures of tmSAHH in complex with NAD+ show both open and closed conformations despite the absence of bound substrate. Each subunit of the tetrameric enzyme is composed of three domains, namely the catalytic domain, the NAD+-binding domain and the C-terminal domain. The NAD+ binding mode is clearly observed and a substrate analogue can also be modeled into the active site, where two cysteine residues in mesophilic enzymes are replaced by serine and threonine in tmSAHH. Notably, the C-terminal domain of tmSAHH lacks the second loop region of mesophilic SAHH, which is important in NAD+ binding, and thus exposes the bound cofactor to the solvent. The difference explains the higher NAD+ requirement of tmSAHH because of the reduced affinity. Furthermore, the feature of missing loop is consistently observed in thermophilic bacterial and archaeal SAHHs, and may be related to their thermostability.





    Categories: Journal Articles
  • Structural insights into specific crRNA G-rich sequence binding by Meiothermus ruber Cse2
    [Apr 2015]

    Publication date: Available online 16 March 2015
    Source:Journal of Structural Biology

    Author(s): Su Liu , Zuanning Yuan , Y. Adam Yuan

    CRISPR (Clustered Regularly Interspersed Short Palindromic Repeats)-mediated defense against invading nucleic acids is a process recently discovered in prokaryotes, which includes recognition and incorporation of invading genetic elements, transcription and processing of CRISPR-RNA (crRNA) and targeting the invaders through base pair recognition. In the type I–E CRISPR–Cas system, Cse2 is proposed to provide a platform to facilitate the targeting of the invading dsDNA by crRNA. Here we report the crystal structure of Meiothermus ruber Cse2 at 2.8Å. M. ruber Cse2 adopts an α-helical bundle scaffold, harbors a positive surface for nucleic acid binding and a conserved dimer interface with strikingly low buried surface area. M. ruber Cse2 selectively binds to G-rich crRNA sequence, which is stripped off from the Cse2-crRNA and Cascade–crRNA complexes by ssDNA or dsDNA with complementary sequence. Stable M. ruber Cascade is readily formed by co-expression of M. ruber Cascade proteins together with G-rich crRNA in vitro. Docking of M. ruber Cse2 structures into the Escherichia coli Cascade Cryo-EM envelope reveals a curved elongated shallow groove for ssRNA binding, which adopts a similar dimer interface discovered by high-resolution crystal structure of Cse2 within E. Coli Cascade. Taken together, our data provides the structural insights into crRNA G-rich sequence recognition by M. ruber Cse2 and reveals the potential structural mechanism for M. ruber Cascade assembly and function.





    Categories: Journal Articles
  • Electron cryotomography of vitrified cells with a Volta phase plate
    [Apr 2015]

    Publication date: Available online 12 March 2015
    Source:Journal of Structural Biology

    Author(s): Yoshiyuki Fukuda , Ulrike Laugks , Vladan Lučić , Wolfgang Baumeister , Radostin Danev

    Electron cryotomography provides a means of studying the three dimensional structure of pleomorphic objects, such as organelles or cells, with a resolution of 1–3nm. A limitation in the study of radiation sensitive biological samples is the low signal-to-noise ratio of the tomograms which may obscure fine details. To overcome this limitation, the recently developed Volta phase plate (VPP) was applied in electron cryotomographic studies of a wide range of cellular structures, from magnetotactic bacteria to primary cultured neurons. The results show that the VPP improves contrast significantly and consequently the signal-to-noise ratio of the tomograms, moreover it avoids disturbing fringing artifacts typical for Zernike phase plates. The contrast improvement provided by the VPP was also confirmed in projection images of relatively thick (∼400nm) samples. In order to investigate the respective contributions of the VPP and the energy filter, images acquired with different combinations of the two were compared. Zero-loss energy filtering reduced the background noise in thicker areas of the sample and improved the contrast of features such as poly-β-hydroxybutyrate granules in magnetotactic bacteria, whereas the VPP provided an overall contrast improvement for all sample areas. After 3D reconstruction, tomograms acquired with the combination of a VPP and an energy filter showed structural features in neuronal processes with outstanding clarity. We also show that the VPP can be combined with focused ion beam milling to examine structures embedded deeply inside cells. Thus, we expect that VPP will become a standard element of the electron cryotomography workflow.





    Categories: Journal Articles
  • The apicomplexan glideosome and adhesins – Structures and function
    [Apr 2015]

    Publication date: Available online 9 March 2015
    Source:Journal of Structural Biology

    Author(s): Lauren E. Boucher , Jürgen Bosch

    The apicomplexan family of pathogens, which includes Plasmodium spp. and Toxoplasma gondii, are primarily obligate intracellular parasites and invade multiple cell types. These parasites express extracellular membrane protein receptors, adhesins, to form specific pathogen–host cell interaction complexes. Various adhesins are used to invade a variety of cell types. The receptors are linked to an actomyosin motor, which is part of a complex comprised of many proteins known as the invasion machinery or glideosome. To date, reviews on invasion have focused primarily on the molecular pathways and signals of invasion, with little or no structural information presented. Over 75 structures of parasite receptors and glideosome proteins have been deposited with the Protein Data Bank. These structures include adhesins, motor proteins, bridging proteins, inner membrane complex and cytoskeletal proteins, as well as co-crystal structures with peptides and antibodies. These structures provide information regarding key interactions necessary for target receptor engagement, machinery complex formation, how force is transmitted, and the basis of inhibitory antibodies. Additionally, these structures can provide starting points for the development of antibodies and inhibitory molecules targeting protein–protein interactions, with the aim to inhibit invasion. This review provides an overview of the parasite adhesin protein families, the glideosome components, glideosome architecture, and discuss recent work regarding alternative models.





    Categories: Journal Articles
  • Cover 2 - Editorial Board
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3









    Categories: Journal Articles
  • Table of Contents / barcode
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3









    Categories: Journal Articles
  • Paper of the Year Award
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3









    Categories: Journal Articles
  • Paper of the Year Award
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3









    Categories: Journal Articles
  • Alignment of direct detection device micrographs using a robust Optical Flow approach
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): Vahid Abrishami , Javier Vargas , Xueming Li , Yifan Cheng , Roberto Marabini , Carlos Óscar Sánchez Sorzano , José María Carazo

    The introduction of direct detection devices in cryo-EM has shown that specimens present beam-induced motion (BIM). Consequently, in this work, we develop a BIM correction method at the image level, resulting in an integrated image in which the in-plane BIM blurring is compensated prior to particle picking. The methodology is based on a robust Optical Flow (OF) approach that can efficiently correct for local movements in a rapid manner. The OF works particularly well if the BIM pattern presents a substantial degree of local movements, which occurs in our data sets for Falcon II data. However, for those cases in which the BIM pattern corresponds to global movements, we have found it advantageous to first run a global motion correction approach and to subsequently apply OF. Additionally, spatial analysis of the Optical Flow allows for quantitative analysis of the BIM pattern. The software that incorporates the new approach is available in XMIPP (http://xmipp.cnb.csic.es).





    Categories: Journal Articles
  • Xlink Analyzer: Software for analysis and visualization of cross-linking data in the context of three-dimensional structures
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): Jan Kosinski , Alexander von Appen , Alessandro Ori , Kai Karius , Christoph W. Müller , Martin Beck

    Structural characterization of large multi-subunit protein complexes often requires integrating various experimental techniques. Cross-linking mass spectrometry (XL-MS) identifies proximal protein residues and thus is increasingly used to map protein interactions and determine the relative orientation of subunits within the structure of protein complexes. To fully adapt XL-MS as a structure characterization technique, we developed Xlink Analyzer, a software tool for visualization and analysis of XL-MS data in the context of the three-dimensional structures. Xlink Analyzer enables automatic visualization of cross-links, identifies cross-links violating spatial restraints, calculates violation statistics, maps chemically modified surfaces, and allows interactive manipulations that facilitate analysis of XL-MS data and aid designing new experiments. We demonstrate these features by mapping interaction sites within RNA polymerase I and the Rvb1/2 complex. Xlink Analyzer is implemented as a plugin to UCSF Chimera, a standard structural biology software tool, and thus enables seamless integration of XL-MS data with, e.g. fitting of X-ray structures to EM maps. Xlink Analyzer is available for download at http://www.beck.embl.de/XlinkAnalyzer.html.





    Categories: Journal Articles
  • Crystal structure of a periplasmic solute binding protein in metal-free, intermediate and metal-bound states from Candidatus Liberibacter asiaticus
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): Nidhi Sharma , Purushotham Selvakumar , Sumit Bhose , Dilip Kumar Ghosh , Pravindra Kumar , Ashwani Kumar Sharma

    The Znu system, a member of ABC transporter family, is critical for survival and pathogenesis of Candidatus Liberibacter asiaticus (CLA). Two homologues of this system have been identified in CLA. Here, we report high resolution crystal structure of a periplasmic solute binding protein from second of the two gene clusters of Znu system in CLA (CLas-ZnuA2) in metal-free, intermediate and metal-bound states. CLas-ZnuA2 showed maximum sequence identity to the Mn/Fe-specific solute binding proteins (SBPs) of cluster A-I family. The overall fold of CLas-ZnuA2 is similar to the related cluster A-I family SBPs. The sequence and structure analysis revealed the unique features of CLas-ZnuA2. The comparison of CLas-ZnuA2 structure in three states showed that metal binding and release is facilitated by a large displacement along with a change in orientation of the side chain for one of the metal binding residue (His39) flipped away from metal binding site in metal-free form. The crystal structure captured in intermediate state of metal binding revealed the changes in conformation and interaction of the loop hosting His39 during the metal binding. A rigid body movement of C-domain along with partial unfolding of linker helix at its C-terminal during metal binding, as reported for PsaA, was not observed in CLas-ZnuA2. The present results suggest that despite showing maximum sequence identity to the Mn/Fe-specific SBPs, the mechanistic resemblance of CLas-ZnuA2 seems to be closer to Zn-specific SBPs of cluster A-I family.





    Categories: Journal Articles
  • Progressive Stochastic Reconstruction Technique (PSRT) for cryo electron tomography
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): Beata Turoňová , Lukas Marsalek , Tomáš Davidovič , Philipp Slusallek

    Cryo Electron Tomography (cryoET) plays an essential role in Structural Biology, as it is the only technique that allows to study the structure of large macromolecular complexes in their close to native environment in situ. The reconstruction methods currently in use, such as Weighted Back Projection (WBP) or Simultaneous Iterative Reconstruction Technique (SIRT), deliver noisy and low-contrast reconstructions, which complicates the application of high-resolution protocols, such as Subtomogram Averaging (SA). We propose a Progressive Stochastic Reconstruction Technique (PSRT) – a novel iterative approach to tomographic reconstruction in cryoET based on Monte Carlo random walks guided by Metropolis–Hastings sampling strategy. We design a progressive reconstruction scheme to suit the conditions present in cryoET and apply it successfully to reconstructions of macromolecular complexes from both synthetic and experimental datasets. We show how to integrate PSRT into SA, where it provides an elegant solution to the region-of-interest problem and delivers high-contrast reconstructions that significantly improve template-based localization without any loss of high-resolution structural information. Furthermore, the locality of SA is exploited to design an importance sampling scheme which significantly speeds up the otherwise slow Monte Carlo approach. Finally, we design a new memory efficient solution for the specimen-level interior problem of cryoET, removing all associated artifacts.





    Categories: Journal Articles
  • Induction of morphological changes in death-induced cancer cells monitored by holographic microscopy
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): Zahra El-Schich , Anna Mölder , Helena Tassidis , Pirkko Härkönen , Maria Falck Miniotis , Anette Gjörloff Wingren

    We are using the label-free technique of holographic microscopy to analyze cellular parameters including cell number, confluence, cellular volume and area directly in the cell culture environment. We show that death-induced cells can be distinguished from untreated counterparts by the use of holographic microscopy, and we demonstrate its capability for cell death assessment. Morphological analysis of two representative cell lines (L929 and DU145) was performed in the culture flasks without any prior cell detachment. The two cell lines were treated with the anti-tumour agent etoposide for 1–3days. Measurements by holographic microscopy showed significant differences in average cell number, confluence, volume and area when comparing etoposide-treated with untreated cells. The cell volume of the treated cell lines was initially increased at early time-points. By time, cells decreased in volume, especially when treated with high doses of etoposide. In conclusion, we have shown that holographic microscopy allows label-free and completely non-invasive morphological measurements of cell growth, viability and death. Future applications could include real-time monitoring of these holographic microscopy parameters in cells in response to clinically relevant compounds.





    Categories: Journal Articles
  • A statistical approach to the initial volume problem in Single Particle Analysis by Electron Microscopy
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): C.O.S. Sorzano , J. Vargas , J.M. de la Rosa-Trevín , J. Otón , A.L. Álvarez-Cabrera , V. Abrishami , E. Sesmero , R. Marabini , J.M. Carazo

    Cryo Electron Microscopy is a powerful Structural Biology technique, allowing the elucidation of the three-dimensional structure of biological macromolecules. In particular, the structural study of purified macromolecules –often referred as Single Particle Analysis(SPA)– is normally performed through an iterative process that needs a first estimation of the three-dimensional structure that is progressively refined using experimental data. It is well-known the local optimisation nature of this refinement, so that the initial choice of this first structure may substantially change the final result. Computational algorithms aiming to providing this first structure already exist. However, the question is far from settled and more robust algorithms are still needed so that the refinement process can be performed with sufficient guarantees. In this article we present a new algorithm that addresses the initial volume problem in SPA by setting it in a Weighted Least Squares framework and calculating the weights through a statistical approach based on the cumulative density function of different image similarity measures. We show that the new algorithm is significantly more robust than other state-of-the-art algorithms currently in use in the field. The algorithm is available as part of the software suite Xmipp (http://xmipp.cnb.csic.es) and Scipion (http://scipion.cnb.csic.es) under the name “Significant”.





    Categories: Journal Articles
  • Cryo-electron tomography of plunge-frozen whole bacteria and vitreous sections to analyze the recently described bacterial cytoplasmic structure, the Stack
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): Lidia Delgado , Gema Martínez , Carmen López-Iglesias , Elena Mercadé

    Cryo-electron tomography (CET) of plunge-frozen whole bacteria and vitreous sections (CETOVIS) were used to revise and expand the structural knowledge of the “Stack”, a recently described cytoplasmic structure in the Antarctic bacterium Pseudomonas deceptionensis M1T. The advantages of both techniques can be complementarily combined to obtain more reliable insights into cells and their components with three-dimensional imaging at different resolutions. Cryo-electron microscopy (Cryo-EM) and CET of frozen-hydrated P. deceptionensis M1T cells confirmed that Stacks are found at different locations within the cell cytoplasm, in variable number, separately or grouped together, very close to the plasma membrane (PM) and oriented at different angles (from 35° to 90°) to the PM, thus establishing that they were not artifacts of the previous sample preparation methods. CET of plunge-frozen whole bacteria and vitreous sections verified that each Stack consisted of a pile of oval disc-like subunits, each disc being surrounded by a lipid bilayer membrane and separated from each other by a constant distance with a mean value of 5.2±1.3nm. FM4-64 staining and confocal microscopy corroborated the lipid nature of the membrane of the Stacked discs. Stacks did not appear to be invaginations of the PM because no continuity between both membranes was visible when whole bacteria were analyzed. We are still far from deciphering the function of these new structures, but a first experimental attempt links the Stacks with a given phase of the cell replication process.





    Categories: Journal Articles
  • Evidence of compositional and ultrastructural shifts during the development of calcareous tubes in the biofouling tubeworm, Hydroides elegans
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): Vera Bin San Chan , Olev Vinn , Chaoyi Li , Xingwen Lu , Anatoliy B. Kudryavtsev , J. William Schopf , Kaimin Shih , Tong Zhang , Vengatesen Thiyagarajan

    The serpulid tubeworm, Hydroides elegans, is an ecologically and economically important species whose biology has been fairly well studied, especially in the context of larval development and settlement on man-made objects (biofouling). Nevertheless, ontogenetic changes associated with calcareous tube composition and structures have not yet been studied. Here, the ultrastructure and composition of the calcareous tubes built by H. elegans was examined in the three early calcifying juvenile stages and in the adult using XRD, FTIR, ICP-OES, SEM and Raman spectroscopy. Ontogenetic shifts in carbonate mineralogy were observed, for example, juvenile tubes contained more amorphous calcium carbonate and were predominantly aragonitic whereas adult tubes were bimineralic with considerably more calcite. The mineral composition gradually shifted during the tube development as shown by a decrease in Sr/Ca and an increase of Mg/Ca ratios with the tubeworm’s age. The inner tube layer contained calcite, whereas the outer layer contained aragonite. Similarly, the tube complexity in terms of ultrastructure was associated with development. The sequential appearance of unoriented ultrastructures followed by oriented ultrastructures may reflect the evolutionary history of serpulid tube biominerals. As aragonitic structures are more susceptible to dissolution under ocean acidification (OA) conditions but are more difficult to be removed by anti-fouling treatments, the early developmental stages of the tubeworms may be vulnerable to OA but act as the important target for biofouling control.





    Categories: Journal Articles
  • Structural and functional analysis of two universal stress proteins YdaA and YnaF from Salmonella typhimurium: possible roles in microbial stress tolerance
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): M. Bangera , R. Panigrahi , S.R. Sagurthi , H.S. Savithri , M.R.N. Murthy

    In many organisms “Universal Stress Proteins” (USPs) are induced in response to a variety of environmental stresses. Here we report the structures of two USPs, YnaF and YdaA from Salmonella typhimurium determined at 1.8Å and 2.4Å resolutions, respectively. YnaF consists of a single USP domain and forms a tetrameric organization stabilized by interactions mediated through chloride ions. YdaA is a larger protein consisting of two tandem USP domains. Two protomers of YdaA associate to form a structure similar to the YnaF tetramer. YdaA showed ATPase activity and an ATP binding motif G-2X-G-9X-G(S/T/N) was found in its C-terminal domain. The residues corresponding to this motif were not conserved in YnaF although YnaF could bind ATP. However, unlike YdaA, YnaF did not hydrolyse ATP in vitro. Disruption of interactions mediated through chloride ions by selected mutations converted YnaF into an ATPase. Residues that might be important for ATP hydrolysis could be identified by comparing the active sites of native and mutant structures. Only the C-terminal domain of YdaA appears to be involved in ATP hydrolysis. The structurally similar N-terminal domain was found to bind a zinc ion near the segment equivalent to the phosphate binding loop of the C-terminal domain. Mass spectrometric analysis showed that YdaA might bind a ligand of approximate molecular weight 800daltons. Structural comparisons suggest that the ligand, probably related to an intermediate in lipid A biosynthesis, might bind at a site close to the zinc ion. Therefore, the N-terminal domain of YdaA binds zinc and might play a role in lipid metabolism. Thus, USPs appear to perform several distinct functions such as ATP hydrolysis, altering membrane properties and chloride sensing.





    Categories: Journal Articles
  • DNA buckling in bacteriophage cavities as a mechanism to aid virus assembly
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): Andrew D. Hirsh , N.C. Perkins

    While relatively simple biologically, bacteriophages are sophisticated biochemical machines that execute a precise sequence of events during virus assembly, DNA packaging, and ejection. These stages of the viral life cycle require intricate coordination of viral components whose structures are being revealed by single molecule experiments and high resolution (cryo-electron microscopy) reconstructions. For example, during packaging, bacteriophages employ some of the strongest known molecular motors to package DNA against increasing pressure within the viral capsid shell. Located upstream of the motor is an elaborate portal system through which DNA is threaded. A high resolution reconstruction of the portal system for bacteriophage ϕ 29 reveals that DNA buckles inside a small cavity under large compressive forces. In this study, we demonstrate that DNA can also buckle in other bacteriophages including T7 and P22. Using a computational rod model for DNA, we demonstrate that a DNA buckle can initiate and grow within the small confines of a cavity under biologically-attainable force levels. The forces of DNA-cavity contact and DNA–DNA electrostatic repulsion ultimately limit cavity filling. Despite conforming to very different cavity geometries, the buckled DNA within T7 and P22 exhibits near equal volumetric energy density (∼1kT/nm3) and energetic cost of packaging (∼22kT). We hypothesize that a DNA buckle creates large forces on the cavity interior to signal the conformational changes to end packaging. In addition, a DNA buckle may help retain the genome prior to tail assembly through significantly increased contact area with the portal.





    Categories: Journal Articles
  • Crystal structures for short-chain pentraxin from zebrafish demonstrate a cyclic trimer with new recognition and effector faces
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): Rong Chen , Jianxun Qi , Hongyu Yuan , Yanan Wu , Wei Hu , Chun Xia

    Short-chain pentraxins (PTXs), including CRP and SAP, are innate pattern recognition receptors that play vital roles in the recognition and elimination of various pathogenic bacteria by triggering the classical complement pathway through C1q. Similar to antibodies, pentraxins can also activate opsonisation and phagocytosis by interacting with Fc receptors (FcRs). Various structural studies on human PTXs have been performed, but there are no reports about the crystal structure of bony fish pentraxins. Here, the crystal structures of zebrafish PTX (Dare-PTX-Ca and Dare-PTX) are presented. Both Dare-PTX-Ca and Dare-PTX are cyclic trimers, which are new forms of crystallised pentraxins. The structures reveal that the ligand-binding pocket (LBP) in the recognition face of Dare-PTX is deep and narrow. Homology modelling shows that LBPs from different Dare-PTX loci differ in shape, reflecting their specific recognition abilities. Furthermore, in comparison with the structure of hCPR, a new C1q binding mode was identified in Dare-PTX. In addition, the FcR-binding sites of hSAP are partially conserved in Dare-PTX. These results will shed light on the understanding of a primitive PTX in bony fish, which evolved approximately 450 million years ago.





    Categories: Journal Articles
  • Large area sub-micron chemical imaging of magnesium in sea urchin teeth
    [Apr 2015]

    Publication date: March 2015
    Source:Journal of Structural Biology, Volume 189, Issue 3

    Author(s): Admir Masic , James C. Weaver

    The heterogeneous and site-specific incorporation of inorganic ions can profoundly influence the local mechanical properties of damage tolerant biological composites. Using the sea urchin tooth as a research model, we describe a multi-technique approach to spatially map the distribution of magnesium in this complex multiphase system. Through the combined use of 16-bit backscattered scanning electron microscopy, multi-channel energy dispersive spectroscopy elemental mapping, and diffraction-limited confocal Raman spectroscopy, we demonstrate a new set of high throughput, multi-spectral, high resolution methods for the large scale characterization of mineralized biological materials. In addition, instrument hardware and data collection protocols can be modified such that several of these measurements can be performed on irregularly shaped samples with complex surface geometries and without the need for extensive sample preparation. Using these approaches, in conjunction with whole animal micro-computed tomography studies, we have been able to spatially resolve micron and sub-micron structural features across macroscopic length scales on entire urchin tooth cross-sections and correlate these complex morphological features with local variability in elemental composition.





    Categories: Journal Articles