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Bernard Moussian - One of the best experts on this subject based on the ideXlab platform.
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Epidermal Cell Surface Structure and Chitin−Protein Co-assembly Determine Fiber Architecture in the Locust Cuticle
ACS Applied Materials & Interfaces, 2020Co-Authors: Sanja Sviben, Jan Henning Dirks, Bernard Moussian, Peter Fratzl, Oliver Spaeker, Mathieu Bennet, Marie Albéric, Luca Bertinetti, Yael PolitiAbstract:The geometrical similarity of helicoidal fiber arrangement in many biological fibrous extracellular matrices, such as bone, plant cell wall, or Arthropod Cuticle, to that of cholesteric liquid mesophases has led to the hypothesis that they may form passively through a mesophase precursor rather than by direct cellular control. In search of direct evidence to support or refute this hypothesis, here, we studied the process of Cuticle formation in the tibia of the migratory locust, Locusta migratoria, where daily growth layers arise by the deposition of fiber arrangements alternating between unidirectional and helicoidal structures. Using focused ion beam/scanning electron microscopy (FIB/SEM) volume imaging and scanning X-ray scattering, we show that the epidermal cells determine an initial fiber orientation, from which the final architecture emerges by the self-organized co-assembly of chitin and proteins. Fiber orientation in the locust Cuticle is therefore determined by both active and passive processes.
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Epidermal cell surface structure and chitin-protein co-assembly determine fiber architecture in the Locust Cuticle
2019Co-Authors: Sanja Sviben, Bernard Moussian, Peter Fratzl, Oliver Spaeker, Mathieu Bennet, Marie Albéric, Luca Bertinetti, A.-h. Dirks, Yael PolitiAbstract:Summary The geometrical similarity of helicoidal fiber arrangement in many biological fibrous extracellular matrices, such as bone, plant cell wall or Arthropod Cuticle, to that of cholesteric liquid mesophases has led to the hypothesis that they may form passively through a mesophase precursor rather than by direct cellular control. In search of direct evidence to support or refute this hypothesis, here, we studied the process of Cuticle formation in the tibia of the migratory locust, Locusta migratoria, where daily growth layers arise by the deposition of fiber arrangements alternating between unidirectional and helicoidal structures. Using FIB/SEM volume imaging and scanning X-ray scattering, we show that the epidermal cells determine an initial fiber orientation from which the final architecture emerges by the self-organized co-assembly of chitin and proteins. Fiber orientation in the locust Cuticle is therefore determined by both active and passive processes.
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Chitin: Structure, Chemistry and Biology.
Advances in Experimental Medicine and Biology, 2019Co-Authors: Bernard MoussianAbstract:Chitin is a linear polysaccharide of the amino sugar N-acetyl glucosamine. It is present in the extracellular matrix of a variety of invertebrates including sponges, molluscs, nematodes and Arthropods and fungi. Generally, it is an important component of protective or supportive extracellular matrices that cover the tissue that produces it or the whole body of the organism. Chitin fibres associate with each other adopting one of three possible crystalline organisations, i.e. α-, β- or γ-chitin. Usually, chitin fibre bundles interact with chitin-binding proteins forming higher order structures. Chitin laminae, which are two-dimensional sheets of α-chitin crystals with antiparallel running chitin fibres in association with β-folded proteins, are primary constituents of the Arthropod Cuticle and the fibrous extracellular matrix in sponges. A tri-dimensional composite material of proteins coacervates and β-chitin constitute hard biomaterials such as the squid beak. The molecular composition of γ-chitin-based structures that contribute to the physical barrier found in insect cocoons is less well studied. In principle, chitin is a versatile extracellular polysaccharide that in association with proteins defines the mechanical properties of tissues and organisms.
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The Arthropod Cuticle
Arthropod Biology and Evolution, 2013Co-Authors: Bernard MoussianAbstract:What accounts for the beauty and singularity of Arthropods is the Cuticle that enables them to compete in their small world. What we see is the surface but what does it look like inside? In the past two centuries, starting with the discovery of chitin as a major component of the Arthropod Cuticle by Odier (1823), a vast number of publications contributed to the understanding of Cuticle architecture and composition (reviewed in Locke 2001; Moussian 2010). The Arthropod Cuticle is a multifunctional coat that defines and stabilises the shape of the body, appendages and internal organs including the hindgut, the foregut and, in insects, the tracheae, preventing dehydration and infection, and protecting against predators of the same scale. As an exoskeleton, additionally, it allows locomotion and flight. Witnessing the ecological success and relevance of Arthropods, the Cuticle is a highly versatile device facilitating formation of many different body shapes that reflect habitat adaptation, and indeed, Arthropods populate a broad range of ecological habitats ranging from oceans to deserts.
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The sulfonylurea receptor Sur is dispensable for chitin synthesis in Drosophila melanogaster embryos.
Pest management science, 2013Co-Authors: Frauke Meyer, Matthias Flötenmeyer, Bernard MoussianAbstract:BACKGROUND Chitin produced by membrane-inserted chitin synthases is an important constituent of the Arthropod Cuticle and midgut peritrophic matrix. Chitin synthesis inhibitors are common insecticides in pest control. As the target of sulfonylurea-derived insecticides such as diflubenzuron, the ABC transporter sulfonylurea receptor (Sur) has been postulated to be an essential cofactor of chitin synthesis. However, direct evidence for this assumption is missing. RESULTS Here, a study has been made of the phenotype of Drosophila melanogaster larvae suffering completely eliminated Sur function. Taken together, it is found that Cuticle architecture is normal and chitin amounts are not diminished in the Cuticle of these animals, indicating that Sur is dispensable for chitin synthesis. CONCLUSION The data obtained suggest that there must exist another sulfonylurea-sensitive ABC transporter that either instead of Sur is the true sulfonylurea-sensitive transporter involved in chitin synthesis or is able to substitute Sur function during Cuticle formation. Identification and characterisation of this factor is pivotal for understanding the mode of action of sulfonylurea as insecticide. © 2013 Society of Chemical Industry
A.c. Neville - One of the best experts on this subject based on the ideXlab platform.
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Printed in Great Britain A BIOLOGICAL SYSTEM PRODUCING A SELF-ASSEMBLING CHOLESTERIC PROTEIN LIQUID CRYSTAL
2015Co-Authors: A.c. Neville, B. M. LukeAbstract:The protein in the oothecal glands of praying mantids (Sphodromantis tenuidentata, Mio-mantis monacha) exists in the form of lamellar liquid crystalline spherulites, which coalesce as they flow out of a punctured gland tubule. Electron micrographs of sections of these spherulites after fixation show parabolic patterns of an electron-light component, set in a continuous matrix of protein. Such patterns arise in helicoidal systems (e.g. Arthropod Cuticle) and microdensito-metric scans of the matrix show a rhythmical electron-density variation consistent with heli-coidal structure. Double spiral patterns identical to those seen in liquid crystal spherulites are illustrated. These properties resemble those of cholesteric liquid crystals. The constructional units appear to be molecular rather than fibrillar as described by previous authors. The helicoidal architecture arises by self-assembly in the gland lumen. Lamellar surface structures self-assembled spontaneously on glass coverslips when the protein was left to stand for several days. When heated to 55 °C, the birefringent liquid crystalline protein abruptly changes to an isotropic gel, with associated loss of parabolic patterning in electron micrographs and of the rhythmical electron-density variation on microdensitometric scans. This behaviour is compared to the formation of gelatin from collagen, in terms of the randomization of an originally ordered secondary structure
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The role of pH, temperature and nucleation in the formation of cholesteric liquid crystal spherulites from chitin and chitosan.
International journal of biological macromolecules, 1998Co-Authors: S.b. Murray, A.c. NevilleAbstract:The alpha chitin and chitosan used in the experiments came from crab shell waste (Sigma). This was treated to form a colloidal suspension of chitin or chitosan crystallites. The electrostatic 'charge coat' surrounding the chitin was then manipulated. This was achieved by alteration of the pH of the chitin or chitosan colloid (Chitin pKa = 6.1). This allowed the charge density on the crystalline rod of chitin or chitosan to be altered. The effect of this treatment was ascertained by measuring the diameter of spherulites formed in vitro. The results were analysed to see if the experimental optimal pH agreed with theoretical approximations. Further investigations were carried out on the initiation of the spherulites and the effect of temperature on spherulite formation. The spherulites form via self assembly through a liquid crystalline cholesteric phase. Manipulation of the electrostatic coat of the chitin could be a method of cellular remote control for formation of the helicoid in Arthropod Cuticle. This would allow the Arthropods to set up conditions that aid the self assembly process.
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The role of the electrostatic coat in the formation of cholesteric liquid crystal spherulites from α-chitin
International journal of biological macromolecules, 1997Co-Authors: S.b. Murray, A.c. NevilleAbstract:Abstract The α-chitin used in the experiments came from crab shell waste. This was boiled in 3M HC1 to form a colloidal suspension of chitin crystallites. The electrostatic ‘coat’ surrounding the chitin was then manipulated in two ways. The first was the alteration of the pH of the chitin colloid (Chitin Ka = 6.1). This allowed the charge density on the crystalline rod of chitin to be altered. The second way was to alter the background charge in the environment by adding salt solutions to the colloid. The effect of the treatments was ascertained by measuring the diameter of the spherulites formed in vitro. These spherulites formed via self assembly through a liquid crystalline cholesteric phase. Raising the pH (within limits), resulted in larger spherulites. Raising the background charge also gave larger spherulites (within limits). As such both background charge and charge on the rod can be used to control the self assembly of the cholesteric spherulites. Manipulation of the electrostatic coat of the chitin could be a method of cellular remote control for formation of the helicoid in Arthropod Cuticle. This would allow the Arthropods to set up conditions that aid the self assembly process.
H. Fabritius - One of the best experts on this subject based on the ideXlab platform.
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preferred crystallographic texture of α chitin as a microscopic and macroscopic design principle of the exoskeleton of the lobster homarus americanus
Acta Biomaterialia, 2007Co-Authors: Dierk Raabe, A Alsawalmih, Sang Bong Yi, H. FabritiusAbstract:Abstract The crystallographic texture of the crystalline α-chitin matrix in the biological composite material forming the exoskeleton of the lobster Homarus americanus has been determined using synchrotron X-ray pole figure measurements and the calculation of orientation distribution functions. The study has two objectives. The first one is to elucidate crystallographic building principles via the preferred synthesis of certain orientations in crystalline organic tissue. The second one is to study whether a general global design principle exists for the exoskeleton which uses preferred textures relative to the local coordinate system throughout the lobster Cuticle. The first point, hence, pursues the question of the extent to which and why α-chitin reveals preferred textures in the lobster Cuticle. The second point addresses the question of why and whether such preferred textures (and the resulting anisotropy) exist everywhere in the exoskeleton. Concerning the first aspect, a strong preference of a fiber texture of the orthorhombic α-chitin is observed which is characterized by a 〈0 2 0〉 crystal axis normal to the exoskeleton surface for the chitin matrix. The second question is tackled by studying samples from different parts of the carapace. While the first aspect takes a microscopic perspective at the basic structure of the biological composite, the second point aims at building a bridge between an understanding of the microstructure and the macroscopic nature of a larger biological construction. We observe that the texture is everywhere in the carapace optimized in such a way that the same crystallographic axis of the chitin matrix is parallel to the normal to the local tangent plane of the carapace. Notable differences in the texture are observed between hard mineralized parts on the one hand and soft membranous parts on the other. The study shows that the complex hierarchical microstructure of the Arthropod Cuticle can be well described by surprisingly simple crystallographic textures.
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Experimental investigation of the elastic-plastic deformation of mineralized lobster Cuticle by digital image correlation.
Journal of structural biology, 2006Co-Authors: C. Sachs, H. Fabritius, Dierk RaabeAbstract:This study presents a novel experimental approach to the characterization of the deformation of a mineralized biological composite using Arthropod Cuticle as a model material. By performing tensile tests combined with a detailed strain analysis via digital image correlation, the elastic–plastic deformation behavior of the endoCuticle of the American lobster Homarus americanus is examined. The test specimens originate from the pincher and crusher claws. For evaluating the effect of moisture on the deformation behavior, the samples are tested both in dry and in wet state. Sample characterization using the digital image correlation method requires a stochastic spot pattern on the sample surface. Digital images are then taken at subsequent deformation stages during the mechanical test. These images are used to calculate the displacement, the displacement gradient, and the strain fields via pattern correlation. The method is applied both, at a global scale to measure with high precision the stress–strain behavior of the bulk Cuticle and at a microscopic scale to reveal strain heterogeneity, strain patterning, and strain localization phenomena.
Dierk Raabe - One of the best experts on this subject based on the ideXlab platform.
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preferred crystallographic texture of α chitin as a microscopic and macroscopic design principle of the exoskeleton of the lobster homarus americanus
Acta Biomaterialia, 2007Co-Authors: Dierk Raabe, A Alsawalmih, Sang Bong Yi, H. FabritiusAbstract:Abstract The crystallographic texture of the crystalline α-chitin matrix in the biological composite material forming the exoskeleton of the lobster Homarus americanus has been determined using synchrotron X-ray pole figure measurements and the calculation of orientation distribution functions. The study has two objectives. The first one is to elucidate crystallographic building principles via the preferred synthesis of certain orientations in crystalline organic tissue. The second one is to study whether a general global design principle exists for the exoskeleton which uses preferred textures relative to the local coordinate system throughout the lobster Cuticle. The first point, hence, pursues the question of the extent to which and why α-chitin reveals preferred textures in the lobster Cuticle. The second point addresses the question of why and whether such preferred textures (and the resulting anisotropy) exist everywhere in the exoskeleton. Concerning the first aspect, a strong preference of a fiber texture of the orthorhombic α-chitin is observed which is characterized by a 〈0 2 0〉 crystal axis normal to the exoskeleton surface for the chitin matrix. The second question is tackled by studying samples from different parts of the carapace. While the first aspect takes a microscopic perspective at the basic structure of the biological composite, the second point aims at building a bridge between an understanding of the microstructure and the macroscopic nature of a larger biological construction. We observe that the texture is everywhere in the carapace optimized in such a way that the same crystallographic axis of the chitin matrix is parallel to the normal to the local tangent plane of the carapace. Notable differences in the texture are observed between hard mineralized parts on the one hand and soft membranous parts on the other. The study shows that the complex hierarchical microstructure of the Arthropod Cuticle can be well described by surprisingly simple crystallographic textures.
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Experimental investigation of the elastic-plastic deformation of mineralized lobster Cuticle by digital image correlation.
Journal of structural biology, 2006Co-Authors: C. Sachs, H. Fabritius, Dierk RaabeAbstract:This study presents a novel experimental approach to the characterization of the deformation of a mineralized biological composite using Arthropod Cuticle as a model material. By performing tensile tests combined with a detailed strain analysis via digital image correlation, the elastic–plastic deformation behavior of the endoCuticle of the American lobster Homarus americanus is examined. The test specimens originate from the pincher and crusher claws. For evaluating the effect of moisture on the deformation behavior, the samples are tested both in dry and in wet state. Sample characterization using the digital image correlation method requires a stochastic spot pattern on the sample surface. Digital images are then taken at subsequent deformation stages during the mechanical test. These images are used to calculate the displacement, the displacement gradient, and the strain fields via pattern correlation. The method is applied both, at a global scale to measure with high precision the stress–strain behavior of the bulk Cuticle and at a microscopic scale to reveal strain heterogeneity, strain patterning, and strain localization phenomena.
S.b. Murray - One of the best experts on this subject based on the ideXlab platform.
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The role of pH, temperature and nucleation in the formation of cholesteric liquid crystal spherulites from chitin and chitosan.
International journal of biological macromolecules, 1998Co-Authors: S.b. Murray, A.c. NevilleAbstract:The alpha chitin and chitosan used in the experiments came from crab shell waste (Sigma). This was treated to form a colloidal suspension of chitin or chitosan crystallites. The electrostatic 'charge coat' surrounding the chitin was then manipulated. This was achieved by alteration of the pH of the chitin or chitosan colloid (Chitin pKa = 6.1). This allowed the charge density on the crystalline rod of chitin or chitosan to be altered. The effect of this treatment was ascertained by measuring the diameter of spherulites formed in vitro. The results were analysed to see if the experimental optimal pH agreed with theoretical approximations. Further investigations were carried out on the initiation of the spherulites and the effect of temperature on spherulite formation. The spherulites form via self assembly through a liquid crystalline cholesteric phase. Manipulation of the electrostatic coat of the chitin could be a method of cellular remote control for formation of the helicoid in Arthropod Cuticle. This would allow the Arthropods to set up conditions that aid the self assembly process.
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The role of the electrostatic coat in the formation of cholesteric liquid crystal spherulites from α-chitin
International journal of biological macromolecules, 1997Co-Authors: S.b. Murray, A.c. NevilleAbstract:Abstract The α-chitin used in the experiments came from crab shell waste. This was boiled in 3M HC1 to form a colloidal suspension of chitin crystallites. The electrostatic ‘coat’ surrounding the chitin was then manipulated in two ways. The first was the alteration of the pH of the chitin colloid (Chitin Ka = 6.1). This allowed the charge density on the crystalline rod of chitin to be altered. The second way was to alter the background charge in the environment by adding salt solutions to the colloid. The effect of the treatments was ascertained by measuring the diameter of the spherulites formed in vitro. These spherulites formed via self assembly through a liquid crystalline cholesteric phase. Raising the pH (within limits), resulted in larger spherulites. Raising the background charge also gave larger spherulites (within limits). As such both background charge and charge on the rod can be used to control the self assembly of the cholesteric spherulites. Manipulation of the electrostatic coat of the chitin could be a method of cellular remote control for formation of the helicoid in Arthropod Cuticle. This would allow the Arthropods to set up conditions that aid the self assembly process.
