Thin Fibrils Research Articles

Histo-Morphological Study on the Footpad of Ostrich (Struthio camelus) In Relation to Locomotion

The ostrich foot has four digital pads, two on the 3rd digit, one on the 4th digit and one at metatarsophalangeal joint. Although these footpads are essential for long distance locomotion of the ostrich, no published data is available on the structure of these footpads. Therefore, the aim of this study is to examine the histo-morphological structure of these footpads in an attempt to highlight their structural functional adaptation for long distance motion. Morphologically, the ventral surface of each footpad is covered by numerous papillae which are varied in direction, length and thickness. In histological examination, the epidermis of the footpad consists of outer stratum corneum and inner stratum germinativum (which is subdivided into basal, intermediate and transitional layers). The stratum corneum has several layers of flattened horney cells. The nuclei of the basal cells have several mitotic figures. The cytoplasm of the stratum germinativum cells has multiple lipid droplets and multigranular bodies (in transitional cells only). Using scanning electron microscope, the collagen fibers in the mid and deep dermis of the footpad run parallel and connect to each other by very thin fibrils which are branched, crossed with each other in an oblique direction. Such arrangement of these collagen fibers and thin fibrils and presence of digital cushion are likely to be responsible for absorption of concussion and hence acceleration of the ostrich movement. We have concluded that ostrich footpads have unique modified structures which are adapted for long distance movement and protection of the underlying soft tissues.

Ultrastructural composition of nonhistone chromosomal skeleton at different stages of mitosis in situ

In interphase cells of the SPEV culture treated with Triton X-100, 2 M NaCl, and DNAse, in the presence of 2 mM CuCl2, we clearly revealed a stabilized nuclear protein material (NPM) composed of a peripheral lamina, residual nucleolus, and internal fibrillar network. This network is formed by thin fibrils 10–20 nm in diameter, which are also revealed in the nonhistone matrix of mitotic chromosomes at all stages of mitosis. In mitotic chromosomes, NPM is represented as a network of the 10–20-nm-thick fibrils without any features of the central-axial structures. Beginning from the middle prophase, it is possible to see approached sister chromatids in contact with each other in certain sites, similar to centromeres. At these sites, the thickness of fibrils increases up to 40–50 nm, whereas the fibrils themselves are disposed more tightly; this structure can be seen in the chromosome until telophase. At the end of telophase, the decondensation of chromosomes and formation of two new nuclei whose NPM is analogous to NPM of usual interphase nucleus are observed. Thus, the NPM elements can perform the role of a skeleton in both the interphase nucleus and mitotic chromosomes.

A first assessment of Galapagos basidiolichens

As part of an ongoing comprehensive inventory of Galapagos lichens, a first assessment of the morphology and anatomy of basidiolichens from the archipelago is presented here. It is the basis for further studies of the taxonomy, ecology and biogeography of this poorly known group of lichens. Four genera, all in Hygrophoraceae, can be distinguished: Acantholichen, Cora, Cyphellostereum and Dictyonema. Both Acantholichen and Cora are characterized by chroococcoid cyanobionts and a heteromerous thallus with a distinct upper cortex and photobiont layer. The monotypic Acantholichen pannarioides is entirely composed of small, branched, inflated squamules that appear densely pruinose because their cortical hyphae bear characteristically swollen, densely spinose end cells (acanthohyphidia); this species has never been observed fertile. The common Cora glabrata is foliose, forming large, radially zonate, conch-like, often tiled thalli, when fertile with circular lines of basidiocarps on its lower side. Dictyonema is distinguished by filamentous cyanobionts and distinctly filamentous thalli that are homomereous (i.e., not distinctly layered); all species of Dictyonema s.str. have trichomes (filamentose cyanobacterial photobionts) closely enveloped by fungal cells of a jigsaw pattern. In D. sericeum thallus filaments (i.e., individual fibrils) aggregate to form shelf-like structures similar in appearance to polyporoid bracket fungi; basidiocarps develop in irregular patches on the lower side of these shelves. In contrast, fibrils of D. schenkianum grow encrusting their substrate with irregularly to suberect trichomes, occasionally bearing basidiocarps dispersed across the thallus. Two other species in Galapagos show adpressed growth form and are described here as new: Dictyonema pectinatum, which is characterized by large parallel fibrils with paler, papillate tips, and D. galapagoense, characterized by thin trichomes of more squarrish elongate cells. The genus Cyphellostereum is represented by two species: the newly described C. imperfectum and an unnamed Cyphellostereum sp., both phenotypically similar to free-living cyanobacterial filaments. Cyphellostereum imperfectum has narrow photobiont filaments with irregular hyphal sheath leaving interspaces; macroscopically it shows a bluish green thallus with a distinct prothallus. Cyphellostereum sp. has a rather uncommon basidiolichen appearance: thin sctytonematoid fibrils surrounded by straight fungal cells forming shiny tufts. The new combination Cyphellostereum nitidum is also proposed. The ecology and taxonomy of Galapagos basidiolichens is briefly discussed and a key and short descriptions of all species are presented.

Effect of Hydrophobic Mutations in the H2-H3 Subdomain of Prion Protein on Stability and Conversion In Vitro and In Vivo

Prion diseases are fatal neurodegenerative diseases, which can be acquired, sporadic or genetic, the latter being linked to mutations in the gene encoding prion protein. We have recently described the importance of subdomain separation in the conversion of prion protein (PrP). The goal of the present study was to investigate the effect of increasing the hydrophobic interactions within the H2-H3 subdomain on PrP conversion. Three hydrophobic mutations were introduced into PrP. The mutation V209I associated with human prion disease did not alter protein stability or in vitro fibrillization propensity of PrP. The designed mutations V175I and T187I on the other hand increased protein thermal stability. V175I mutant fibrillized faster than wild-type PrP. Conversion delay of T187I was slightly longer, but fluorescence intensity of amyloid specific dye thioflavin T was significantly higher. Surprisingly, cells expressing V209I variant exhibited inefficient proteinase K resistant PrP formation upon infection with 22L strain, which is in contrast to cell lines expressing wild-type, V175I and T187I mPrPs. In agreement with increased ThT fluorescence at the plateau T187I expressing cell lines accumulated an increased amount of the proteinase K-resistant prion protein. We showed that T187I induces formation of thin fibrils, which are absent from other samples. We propose that larger solvent accessibility of I187 in comparison to wild-type and other mutants may interfere with lateral annealing of filaments and may be the underlying reason for increased conversion efficiency.

Shear‐induced fibrillation and resultant mechanical properties of injection‐molded polyamide 1010/isotactic polypropylene blends

AbstractIt is feasible to control the phase morphology and orientation for immiscible polymer blends to manipulate their properties. In this paper, the blend of polyamide 1010 (PA1010) and isotactic polypropylene (iPP) (mainly at a fixed ratio of PA1010/iPP = 80/20) was used as an example to demonstrate the effect of shear on the morphology and resultant mechanical properties. After being melt blended, the injection‐molded bars were prepared via a dynamic packing equipment to impose a prolonged shearing on the melts during the solidification stage. By controlling the shear time, the structure evolution and morphological development of the blends can be well controlled. Mechanical measurement of the molded bar showed a dramatically improved tensile property and impact strength with increasing shear time. Morphological examination revealed that the iPP droplets are elongated and become thin fibrils along the shear direction with increasing shear time. The shear‐induced fibrillation, instead of orientation, is believed to be responsible for the largely improved properties of the blend, particularly for the impact strength. The toughening mechanism is discussed based on the combined effect of hindrance of crack propagation and the transferring and bearing of the load due to the existence of the fibrils. This was further proved by changing the blending ratio and using low molecular weight iPP. Finally, we propose a concept for designing blending materials with good comprehensive properties. Copyright © 2011 Society of Chemical Industry

Polybenzimidazole gel membrane for the use in fuel cell

Thermoreversible gelation of polybenzimidazole (PBI) in phosphoric acid (PA) is investigated by studying the gel morphology, thermodynamics of the gelation, and gelation kinetics utilizing test tube tilting and UV–Vis spectroscopy techniques. Gelation kinetics studies reveal that both the gelation rate and critical gelation concentration (C∗t=∞) are function of gelation temperature (Tgel) and the molecular weight of PBI. Highly dense fibrillar network morphology with large number of longer and thinner fibrils is obtained for higher gel concentration and higher molecular weight PBI. Both the gel melting (Tgm) and gelation (Tgel) temperature depend upon the gelation concentration and molecular weight of PBI. The presence of self-assembled chains of PA molecules, which help to produce the PBI crystallites, is observed from the thermodynamical study. I.R. and Raman studies prove the presence of strong hydrogen bonding interaction between the PBI and the PA molecules, and the free PA molecules in the gel network. The gelation occurs in two-step processes which include a slow rate determining conformational transition from coil to rod and followed by aggregation of rod via crystallization. The PA loading of PBI membrane obtained from the PBI–PA gel is significantly high compared to the conventional imbibing process membrane. The PBI gel membrane displays very high thermal and mechanical stabilities. The high acid loading and superb thermo-mechanical stability are due to the gel network structure of the membrane. The proton conductivity of the membrane at 160°C and 0% relative humidity (RH) is ∼0.1Scm−1, which is higher than the reported values in the literature for the PBI. The activation energy of the proton conduction is 14–15kJ/mol indicating faster proton transfer by hopping process inside the gel network.

Fine Structure of Extracellular Fibers in Primo-nodes and Vessels

To investigate the extracellular matrices in the primo-nodes (PNs) and vessels (PVs) (Bonghan corpuscles and ducts), fine structure of the fibers comprising the extracellular matrices was studied in relation to the diameter and the periodicity to identify the types of the fibers. Electron micrographs of the fibers from the previously published works on the PNs and PVs were analyzed by using MATLAB programming and ImageJ software. The extracellular fibrous components of the PNs and PVs could be classified generally into two groups—thin collagen fibrils and thick non-collagenous wavy bent fibers. The thick bent fibers were fibrin-like. The diameters of the thick bent fibers were 30–200 nm and they were highly bent. This group included organ surface PNs and lymphatic PNs/PVs. The diameters of the collagen fibrils were 30–70 nm. Organ surface, heart, and hypodermis PVs were categorized in this group. The periodicity of bent fibers in an organ surface PN was 16.1 ± 0.2 (SE) nm, and the periodicity of collagen fibrils in the hypodermis PVs was 37.4 ± 0.5 (SE) nm. Further investigations are required to reveal the physiological implications of the two types of fibers in the PNs and PVs.

Aggregation and structural changes of α S1-, β- and κ-caseins induced by homocysteinylation

Elevated homocysteine levels are resulting in N-homocysteinylation of lysyl residues in proteins and they correlate with a number of human pathologies. However, the role of homocysteinylation of lysyl residues is still poorly known. In order to study the features of homocysteinylation of intrinsically unstructured proteins (IUP) bovine caseins were used as a model. α S1-, β- and κ-caseins, showing different aggregations and micelle formation, were modified with homocysteine-thiolactone and their physico-chemical properties were studied. Efficiency of homocysteine incorporation was estimated to be about 1.5, 2.1 and 1.3 homocysteyl residues per one β-, α S1-, and κ-casein molecule, respectively. Use of intrinsic and extrinsic fluorescent markers such as Trp, thioflavin T and ANS, reveal structural changes of casein structures after homocysteinylation reflected by an increase in beta-sheet content, which in some cases may be characteristic of amyloid-like transformations. CD spectra also show an increase in beta-sheet content of homocysteinylated caseins. Casein homocysteinylation leads in all cases to aggregation. The sizes of aggregates and aggregation rates were dependent on homocysteine thiolactone concentration and temperature. DLS and microscopic studies have revealed the formation of large aggregates of about 1–3 μm. Homocysteinylation of α S1- and β-caseins results in formation of regular spheres. Homocysteinylated κ-casein forms thin unbranched fibrils about 400–800 nm long. In case of κ-casein amyloidogenic effect of homocysteinylation was confirmed by Congo red spectra. Taken together, data indicate that N-homocysteinylation provokes significant changes in properties of native caseins. A comparison of amyloidogenic transformation of 3 different casein types, belonging to the IUP protein family, shows that the efficiency of amyloidogenic transformation upon homocysteinylation depends on micellization capacity, additional disulphide bonds and other structural features.

Amyloid Fibrils Formation of Concanavalin A at Basic pH

Mechanisms of partial unfolding and aggregation of proteins are of extreme interest in view of the fact that several human pathologies are characterized by the formation and deposition of protein-insoluble material, mainly composed of amyloid fibrils. Here we report on an experimental study on the heat-induced aggregation mechanisms, at basic pH, of concanavalin A (ConA), used as a model system. Thioflavin T (ThT) fluorescence and multiangle light scattering allowed us to detect different intertwined steps in the formation of ConA aggregates. In particular, the ThT fluorescence increase, observed in the first phase of aggregation, reveals the formation of intermolecular β-sheet structure which constitutes a rate-limiting step of the process. The intertwining between the formation of β-aggregate structures and the whole aggregation process is discussed as a function of protein concentration: a coagulation process produces the same kind of aggregates at the different concentrations studied. Multiangle light-scattering data highlight the onset of the condensation process which gives rise to formation of compact fractal aggregates. AFM microscopy supports this conclusion showing thin fibrils of ConA, formed in the early stage of aggregation, which further interact to form larger structures with a netlike spatial organization.

Lipid matrix plays a role in Abeta fibril kinetics and morphology

While neuronal membranes are proposed to be the primary target of amyloid plaques, the effect of phospholipids on fibril formation kinetics and morphology has not yet been resolved. We report that interaction of various compositions with neuronal mimics promoted different processes of fibril formation: negatively charged surfaces increased the lag time and elongation rate in thioflavin T assays, while brain total lipid extract had an opposite effect compared to that in the absence of lipid. Electron microscopy showed thin and elongated fibrils when the peptide was incubated with anionic lipids, while neutral surfaces promoted coarse and small fibrils. Circular dichroism and thioflavin T assays confirmed an initially unstructured peptide, and measured its transition to an aggregated beta-sheet conformation. Structured summary Amyloid beta(1–42) binds to Amyloid beta(1–42) by circular dichroism (View interaction) Amyloid beta(1–42) binds to Amyloid beta(1–42) by fluorescence technology (View interaction) Amyloid beta(1–42) binds to Amyloid beta(1–42) by electron microscopy (View interaction).

Ultrastructure of the mesoglea of the sea anemone Nematostella vectensis (Edwardsiidae)

Abstract. Cnidarians have extracellular matrix, or mesoglea, situated between an outer epidermis and an inner gastrodermis. In this article, we describe the ultrastructure of the mesoglea of polyps of Nematostella vectensis during development and regeneration. The column wall of recently metamorphosed polyps had basal laminae composed of a meshwork of thin filaments underlying each epithelium and a network of unstriated thick (20–25 nm in diameter) and thin fibrils (∼5 nm) decorated with particulate matter. In juvenile polyps with eight tentacles, the system of thick fibrils was concentrated near the gastrodermis. In the column wall and mesenteries of the adult there were bundles of thick fibrils that ran parallel to the myonemes. In regenerating polyps 2 days after transection, the network of thin fibrils and particulate material as well as the basal lamina largely disappeared in the healing part of the oral, but not aboral, half. In the regenerating portion of the aboral half 1 and 2 days after transection, the bundles of thick fibrils were smaller and less organized, and the basal laminae were thicker than in the column wall of untransected polyps. In both regenerating halves, the general organization of the mesoglea of normal polyps was reattained by 5 days after transection. At all stages the mesoglea contained cellular processes that may belong to amebocytes; nucleated amebocytes with a range of shapes were present in the mesoglea of the column wall and mesenteries of adult polyps. Certain features of the mesoglea of members of N. vectensis and Hydra are similar, especially the ultrastructure of the basal laminae, but the fibrillar systems of these two model cnidarians are different. Temporal and spatial differences in the composition of the mesoglea of N. vectensis point to different roles for its components during development and regeneration.

Ultrastructure of irregular collagen fibrils of shark mandible

Sawada T. and Inoue S. 2011. Ultrastructure of irregular collagen fibrils of shark mandible. —Acta Zoologica (Stockholm) 92: 62–66. Collagen fibrillogenesis was investigated in developing fibrous connective tissue (tooth band) in shark mandible by transmission electron microscopy. Fibrils varied considerably in shape and size. Both thin and thick fibrils 40–200 and 400–500 nm in width, respectively, were observed, with the latter showing irregular contours. Examination of both transverse and longitudinal sections of fibril suggested that the irregular, thick fibrils were formed by fusion of the thin fibrils. This was in agreement with a previously proposed mechanism of collagen fibrillogenesis in a variety of tissues, in which formation of thin fibrils is followed by their coalescence into thicker fibrils. Detailed high resolution ultrastructural examination revealed decorin-like, 4.5- to 5.5-nm-wide polygonal frames and 3-nm-wide ribbon-like structures previously identified as chondroitin sulfate proteoglycan ‘double tracks’ localized within the interfibrillar spaces. These structures may be closely involved in collagen fibrillogenesis.

In Sup35p filaments (the [PSI+] prion), the globular C‐terminal domains are widely offset from the amyloid fibril backbone

In yeast cells infected with the [PSI+] prion, Sup35p forms aggregates and its activity in translation termination is downregulated. Transfection experiments have shown that Sup35p filaments assembled in vitro are infectious, suggesting that they reproduce or closely resemble the prion. We have used several EM techniques to study the molecular architecture of filaments, seeking clues as to the mechanism of downregulation. Sup35p has an N-terminal 'prion' domain; a highly charged middle (M-)domain; and a C-terminal domain with the translation termination activity. By negative staining, cryo-EM and scanning transmission EM (STEM), filaments of full-length Sup35p show a thin backbone fibril surrounded by a diffuse 65-nm-wide cloud of globular C-domains. In diameter (∼8 nm) and appearance, the backbones resemble amyloid fibrils of N-domains alone. STEM mass-per-unit-length data yield ∼1 subunit per 0.47 nm for N-fibrils, NM-filaments and Sup35p filaments, further supporting the fibril backbone model. The 30 nm radial span of decorating C-domains indicates that the M-domains assume highly extended conformations, offering an explanation for the residual Sup35p activity in infected cells, whereby the C-domains remain free enough to interact with ribosomes.

Focal Phosphatidylserine Exposure on Stressed Endothelial Cells In Relation to Membrane Topology: A Potential Basis for Compartmentalization of Procoagulant and Anticoagulant Activities

AbstractAbstract 4321Exposure of endothelial cells to toxins or deprivation of nutrients leads to cell stress and, subsequently, to apoptosis. Apoptosis is associated with gross translocation of phosphatidylserine (PS) to the external membrane leaflet and exposed PS is required for coagulation enzyme complexes as well as some anticoagulant activities. However, in vivo studies of mouse thrombosis do not show apoptotic cells or gross PS exposure associated with clot formation, thus suggesting that PS supporting thrombosis is primarily derived from viable cells with limited PS exposure rather than apoptotic cells. In preliminary studies, we have found that cell stress, on multiple cell types, leads to limited, focal PS exposure before the onset of apoptosis. In this study, we have asked about the distribution of focal, PS-containing micro-domains on stressed endothelial cells. To induce stress we exposed Human Umbilical Vein Endothelial Cells (HUVEC) to 0.5 μM staurosporine for 15 minutes. PS exposure was detected by simultaneous staining using 10 nM lactadherin–Alexa 488 and annexin V–Cy 3.18, both exhibiting high affinity for PS. Stressed cells partially withdrew from their prior borders, leaving residual fibrils connected to original attachment points. In addition, they extended new thin fibrils that were up to several cell diameters in length. Confocal microscopy demonstrated focal staining, with little overlap between regions stained by lactadherin and regions stained by annexin V. Lactadherin stained the new thin fibrils, stretches of the cell margin, and patches near the nucleus. In contrast, annexin V stained in a reticular pattern in the perinuclear region. Based on the previously demonstrated finding, that lactadherin has a preference for highly curved vesicles and annexin V for flat or concave surfaces, we asked whether the selective binding might be determined by the membrane topology. To mimic the curvature of a cell membrane we prepared nano-fabricated silica substrates with ridges of 10 nm and 30 nm radii of curvature. The AFM topographic and fluorescent images of synthetic membrane bilayers supported by the substrates showed that, over a PS content of 4–15%, lactadherin preferentially binds to the convex nano-ridges with a ridge: valley staining ratio of approx. 280:1, while annexin V selectively binds the concave areas of the nano-trenches with a ridge: valley staining ratio of approx. 1:110. Combined fluorescence/AFM imaging of stressed HUVEC, demonstrated that the new thin filaments staining with lactadherin had radii of curvature of approx.12 nm, which was similar to the ridges of our synthetic bilayers. The reticular staining of the perinuclear region by annexin V correlated to concavities between nodules on the cell, suggesting that the selective staining is due, in part, to membrane topology. We are currently assessing the focal binding of procoagulant and anticoagulant proteins to the stressed endothelial cells. Because, factor V and factor VIII prefer the convex surfaces recognized by lactadherin we predict that procoagulant enzyme complexes will localize to these topographic features. Annexin II, which serves as a receptor for tPA, plasmin, and factor X, is predicted to prefer concavities, similar to annexin V. This could provide a basis for separate compartments of procoagulant and anticoagulant or fibrinolytic activity on the same cell. Disclosures:No relevant conflicts of interest to declare.

Comparative Study on Histological Structures of the Vitelline Membrane of Hen and Duck Egg Observed by Cryo-Scanning Electron Microscopy

The histological structures of the vitelline membranes (VM) of hen and duck eggs were observed by cryo-scanning electron microscopy (cryo-SEM), and the chemical characteristics were also compared. The outer layer surface (OLS) of duck egg VM showed networks constructed by fibrils and sheets (0.1-5.2 microm in width), and that of hen egg presented networks formed only by sheets (2-6 microm in width). Thicker fibrils (0.5-1.5 microm in width) with different arrangement were observed on the inner layer surface (ILS) of duck egg VM as compared to those (0.3-0.7 microm in width) of hen egg VM. Upon separation, the outer surface of the outer layer (OSOL) and the inner surface of the inner layer (ISIL) of hen and duck egg VMs were quite similar to fresh VM except that the OSOL of duck egg VM showed networks constructed only by sheets. Thin fibrils interlaced above a bumpy or flat structure were observed at the exposed surface of the outer layer (ESOL) of hen and duck egg VMs. The exposed surfaces of inner layers (ESIL) of hen and duck egg VMs showed similar structures of fibrils, which joined, branched, and ran in straight lines for long distances up to 30 microm; however, the widths of the fibrils shown in ESOL and ESIL of duck egg VM were 0.1 and 0.7-1.4 microm, respectively, and were greater than those (<0.1 and 0.5-0.8 microm) of hen egg VM. The continuous membranes of both hen and duck egg VMs were still attached to the outer layers when separated. The content of protein, the major component of VM, was higher in duck egg VM (88.6%) than in hen egg VM (81.6%). Four and six major SDS-soluble protein patterns with distinct localization were observed in hen and duck egg VMs, respectively. Overall, the different histological structures of hen and duck egg VMs were suggested to be majorly attributable to the diverse protein components.

Large-scale polymorphism and auto-catalytic effect in insulin fibrillogenesis

Under specific conditions the protein hormone insulin is prone to form amyloid fibrils and is widely used as a model system to study fibril formation mechanisms. In this work we studied thermally induced fibril formation of insulin in acidic solutions. We mainly focused on the effect of the initial protein concentration on the final fibril morphology and the connection between morphology and secondary nucleation mechanisms. Atomic force microscopy (AFM) analysis revealed a significant fibril polymorphism on the macroscopic level dependent on protein concentration, ranging from thin and elongated fibrils to highly complex superstructures. Moreover, amyloid superstructures formed at high insulin concentration resulted in a lower propensity in being stained by Thioflavin T (ThT) and, for these structures, a reduced catalytic effect in seeding experiments was also detected. These results suggest a crucial involvement of the macroscopic properties of fibril surfaces in determining secondary nucleation pathways in insulin fibrillation.

Inhibition of Amyloid Fibrillization and Dissociation of Matured Amyloid Fibrils by Mj HSP16.5

The amyloid fibrillization of proteins and peptides is related to many human diseases including Alzheimer's disease.Currently there is no effective therapy for these diseases, because the mechanism of the amyloid fibrillization is still not clear.Understanding how to effectively inhibit amyloid formation will shed light on the prevention and treatment of these diseases.Transtheritin (TTR) and its mutants easily form amyloid fibrils and are related to many diseases.Mj HSP16.5, a small heat shock protein (SHSP) from Methanococcus jannaschii shows high chaperone-like activity under acidic conditions, and these conditions promote the fibrillization of many peptides.We studied the influence of Mj HSP16.5 on the fibrillization of the peptide WTTR (sequence:WYTIAALLSPYS, i.e., the 105-115 fragment of TTR with a tryptophan added to its N-terminal).Mj HSP16.5 was found to significantly inhibit the growth and maturation of the WTTR fibrils resulting in much thinner fibrils compared to those under normal conditions.More interestingly, Mj SHSP16.5 can dissociate the matured WTTR fibrils.Based on our experimental results, a possible inhibition mechanism was proposed in which Mj SHP16.5 interacted with WTTR fibrils and/or seeds.

Structural and biochemical aspects of keratan sulphate in the cornea

Keratan sulphate (KS) is the predominant glycosaminoglycan (GAG) in the cornea of the eye, where it exists in proteoglycan (PG) form. KS-PGs have long been thought to play a pivotal role in the establishment and maintenance of the array of regularly-spaced and uniformly- thin collagen fibrils which make up the corneal stroma. This characteristic arrangement of fibrils allows light to pass through the cornea. Indeed, perturbations to the synthesis of KS-PG core proteins in genetically altered mice lead to structural matrix alterations and corneal opacification. Similarly, mutations in enzymes responsible for the sulphation of KS-GAG chains are causative for the inherited human disease, macular corneal dystrophy, which is manifested clinically by progressive corneal cloudiness starting in young adulthood.

Collagen fibril organization in the pregnant endometrium of decorin‐deficient mice

In the pregnant mouse endometrium, collagen fibrillogenesis is characterized by the presence of very thick collagen fibrils which are topographically located exclusively within the decidualized stroma. This dynamic biological process is in part regulated by the small leucine-rich proteoglycans decorin and biglycan. In the present study we utilized wild-type (Dcn(+/+)) and decorin-deficient (Dcn(-/-)) time-pregnant mice to investigate the evolution of non-decidualized and decidualized collagen matrix in the uterine wall of these animals. Ultrastructural and morphometric analyses revealed that the organization of collagen fibrils in the pregnant endometrium of both non-decidualized and decidualized stroma showed a great variability of shape and size, regardless of the genotype. However, the decidualized endometrium from Dcn(-/-) mice contained fibrils with larger diameter and more irregular contours as compared to the wild-type littermates. In the Dcn(-/-) animals, the proportion of thin (10-50 nm) fibrils was also higher as compared to Dcn(+/+) animals. On day 7 of pregnancy, biglycan was similarly localized in the decidualized endometrium in both genotypes. Lumican immunostaining was intense both in decidualized and non-decidualized stroma from Dcn(-/-) animals. The present results support previous findings suggesting that decorin participates in uterine collagen fibrillogenesis. In addition, we suggest that the absence of decorin disturbs the process of lateral assembly of thin fibrils, resulting in very thick collagen fibrils with irregular profiles. Our data further suggest that decorin, biglycan and lumican might play an interactive role in collagen fibrillogenesis in the mouse endometrium, a process modulated according to the stage of pregnancy.

Spectroscopic characterization of natural chrysotile

Chrysotile, a variety of serpentine mineral was investigated by vibrational and magnetic resonance spectroscopic methods. The SEM photograph of the sample shows that chrysotile is made up of thin and flexible fibrils, classified as asbestos. The calculated lattice parameters were a = 5.1961 ± 0.0053 Å, b = 9.2365 ± 0.0107 Å, c = 14.6208 ± 0.0039 Å; β = 90.15 ± 0.19°; Z = 4, with space group C2/ m. Three bands observed in the highest wavenumber region (3689 and 3648 cm −1) originate from the stretching vibrations of the two crystallographically different OH groups. The Raman spectrum shows bending vibrations of the SiO 4 tetrahedra at 390 and 348 cm −1. Substitution of the Si ions in SiO 4 tetrahedra by Al ions leads to low-field shifts in the 29Si NMR spectrum and the resonance line corresponding to Q 3 (1 Al) was observed at −89 ppm. This result was supported by the resonance line at ≈57 ppm in 27Al NMR spectrum.