A remarkably strong natural glassy rod: the anchoring spicule of theMonorhaphis sponge (original) (raw)
Related papers
30. Siliceous Sponge Spicules from Site 7951
1992
Siliceous sponge spicules are present in sediments drilled during Leg 127. The sponge spicule abundances are tabulated for Hole 795A. Pliocene and Pleistocene sponge spicules consist mostly of monaxons, sporadically intermixed with isochelae, polyaxons, and other spicule morphologies.
Frontiers in Zoology
Background A basal spicule of the hexactinellid sponge Monorhaphis chuni may reach up to 3 m in length and 10 mm in diameter, an extreme case of large spicule size. Generally, sponge spicules are of scales from micrometers to centimeters. Due to its large size many researchers have described its structure and properties and have proposed it as a model of hexactinellid spicule development. Thorough examination of new material of this basal spicule has revealed numerous inconsistencies between our observations and earlier descriptions. In this work, we present the results of detailed examinations with transmitted light and epifluorescence microscopy, SEM, solid state NMR analysis, FTIR and X-ray analysis and staining of Monorhaphis chuni basal spicules of different sizes, collected from a number of deep sea locations, to better understand its structure and function. Results Three morphologically/structurally different silica layers i.e. plain glassy layer (PG), tuberculate layer (TL) ...
Evidence-Based Complementary and Alternative Medicine, 2011
The depth of the ocean is plentifully populated with a highly diverse fauna and flora, from where the Challenger expedition (1873-1876) treasured up a rich collection of vitreous sponges [Hexactinellida]. They have been described by Schulze and represent the phylogenetically oldest class of siliceous sponges [phylum Porifera]; they are eye-catching because of their distinct body plan, which relies on a filigree skeleton. It is constructed by an array of morphologically determined elements, the spicules. Later, during the German Deep Sea Expedition "Valdivia" (1898-1899), Schulze could describe the largest siliceous hexactinellid sponge on Earth, the up to 3 m high Monorhaphis chuni, which develops the equally largest bio-silica structures, the giant basal spicules (3 m × 10 mm). With such spicules as a model, basic knowledge on the morphology, formation, and development of the skeletal elements could be elaborated. Spicules are formed by a proteinaceous scaffold which mediates the formation of siliceous lamellae in which the proteins are encased. Up to eight hundred 5 to 10 μm thick lamellae can be concentrically arranged around an axial canal. The silica matrix is composed of almost pure silicon and oxygen, providing it with unusual optophysical properties that are superior to those of man-made waveguides. Experiments indicated that the spicules function in vivo as a nonocular photoreception system. In addition, the spicules have exceptional mechanical properties, combining mechanical stability with strength and stiffness. Like demosponges the hexactinellids synthesize their silica enzymatically, via the enzyme silicatein. All these basic insights will surely contribute also to a further applied utilization and exploration of bio-silica in material/medical science.
Microscopy Research and Technique, 2003
Silica deposition is a fundamental process in sponges. Most sponges in the Classes Demospongiae and Hexactinellida secrete siliceous elements, which can subsequently fuse, interlock with each other, or form three-dimensional structures connected by spongin. The resulting skeletal frameworks allow sponges to grow upwards and facilitate water exchange with minimal metabolic cost. Several studies on sponge skeletogenesis have been published. We are beginning to understand the mechanisms of spicule secretion and the role of spicules and skeletal frameworks in the biology, ecology, and evolution of sponges. Molecular techniques and ecological experiments have demonstrated the genetic control of the process and the contribution of environmental factors to the expression of a sponge spicule, respectively. However, other classic topics such as the role of membranes in silicon transport or whether spicules are formed in situ or secreted anywhere in the sponge mesohyl and then transported to the skeletal framework require further investigation. We review the process of silica deposition in sponges at the molecular and cellular levels, as well as the biological and ecological functions of spicules and skeletons. The genetic control of spicule shapes makes them useful in the reconstruction of sponge phylogeny, although recent experiments have demonstrated the influence of environmental factors in modulating spicule size, shape, and the presence or absence of one or more spicule types. The implications of such variations in sponge taxonomy may be important. Besides supporting sponge cells, spicules can help larvae stay buoyant while in the plankton or reach the bottom at settlement, enhance reproduction success, or catch prey. Conversely, the role of spicules and skeletons in deterring predation has not been demonstrated. Knowledge of several aspects is still based on a single or a few species and extrapolations should be made only with caution. With the advent of new molecular techniques, new lines of research are presently open and active in this field.
Structural Arrangement and Properties of Spicules in Glass Sponges
ISRN Materials Science, 2011
The morphology, chemical composition, and optical properties of long monoaxonic spicules were studied in several species of marine deep-sea hexactinellid sponges of different orders and families:Asconema setubalense(Hexasterophora, Lyssacinosida) andMonorhaphis chuniSchulze (Monorhaphiidae). Their macrostructural organization is a system of thin layers laid around the central cylinder containing a square canal filled with organic matter. A significant role in spicule organization is played by the organic matrix. The macrostructural of organization of the spicule inMonorhaphis chuniis a system of the “cylinder-within-a-cylinder” type. However the spicule surface is covered with ridges. They penetrate a few layers into the spicule. Analysis of the elemental composition of the basalia spicule ofMonorhaphis chunidemonstrates a heterogeneous allocation of C, O, Si on the spicule surface, subsurface layers, and on ridges. All studied spicules have the properties of anisotropic crystals an...
Siliceous Sponge Spicules from Site 795
Proceedings of the Ocean Drilling Program, 1992
Siliceous sponge spicules are present in sediments drilled during Leg 127. The sponge spicule abundances are tabulated for Hole 795A. Pliocene and Pleistocene sponge spicules consist mostly of monaxons, sporadically intermixed with isochelae, polyaxons, and other spicule morphologies.
Siliceous sponge spicules in coral reef sediments
Marine Biology, 1978
Experimental etching with hydrofluoric acid indicated that silica deposition occurs in a recognizable pattern in common sponge microscleres. The postdepositional alteration of these spicules has previously been generally unrecognized or misinterpreted in the literature. Early stages of postdepositional etching of sponge spicules were observed in the acid insoluble fraction of sediments from the West Atlantic barrier reef near Carrie Bow Cay, Belize. Preliminary data on silica distribution in the Belize barrier reef show that concentrations in fine sediment «0.25 mm) increase landward of the main reef tract. Sponge spicules are the main component of particulate silica in sediments of the reef and fore-reef where sponge populations abound, whereas grains prevail in the back-reef lagoon deposits. Recycling of locally dissolved silica appears to be important for the growth of many offshore reef sponges.
The giant basal spicule of the hexactinellid sponge Monorhaphis chuni represents the longest natural siliceous structure on Earth. This spicule is composed of concentrically arranged lamellae that are approximately 10m thick. In the present study, we investigated the formation of outer lamellae on a cellular level using microscopic and spectroscopic techniques. It is shown that the formation of an outermost lamella begins with the association of cell clusters with the surface of the thickening and/or growing spicule. The cells release silica for controlled formation of a lamella. The pericellular (silica) material fuses to a delimited and textured layer of silica with depressions approximately 20-30m in diameter. The newly formed layer initially displays 40m wide, well-structured banded ribbons and only attains its plain surface in a final step. The chemical composition in the depressions was studied using energy dispersive X-ray spectroscopy and by staining with Texas Red. The data suggest that those depressions are the nests for the silica-forming cells and that silica formation starts with a direct association of silicaforming cells with the outer surface of the spicule, where they remain and initiate the development of the next lamellae.
Journal of Structural Biology, 2008
The giant basal spicules of the siliceous sponges Monorhaphis chuni and Monorhaphis intermedia (Hexactinellida) represent the largest biosilica structures on earth (up to 3 m long). Here we describe the construction (lamellar organization) of these spicules and of the comitalia and highlight their organic matrix in order to understand their mechanical properties. The spicules display three distinct regions built of biosilica: (i) the outer lamellar zone (radius: >300 μm), (ii) the bulky axial cylinder (radius: <75 μm), and (iii) the central axial canal (diameter: <2 μm) with its organic axial filament. The spicules are loosely covered with a collagen net which is regularly perforated by 7–10 μm large holes; the net can be silicified. The silica layers forming the lamellar zone are ≈5 μm thick; the central axial cylinder appears to be composed of almost solid silica which becomes porous after etching with hydrofluoric acid (HF). Dissolution of a complete spicule discloses its complex structure with distinct lamellae in the outer zone (lamellar coating) and a more resistant central part (axial barrel). Rapidly after the release of the organic coating from the lamellar zone the protein layers disintegrate to form irregular clumps/aggregates. In contrast, the proteinaceous axial barrel, hidden in the siliceous axial cylinder, is set up by rope-like filaments. Biochemical analysis revealed that the (dominant) molecule of the lamellar coating is a 27-kDa protein which displays catalytic, proteolytic activity. High resolution electron microscopic analysis showed that this protein is arranged within the lamellae and stabilizes these surfaces by palisade-like pillars. The mechanical behavior of the spicules was analyzed by a 3-point bending assay, coupled with scanning electron microscopy. The load-extension curve of the spicule shows a biphasic breakage/cracking pattern. The outer lamellar zone cracks in several distinct steps showing high resistance in concert with comparably low elasticity, while the axial cylinder breaks with high elasticity and lower stiffness. The complex bioorganic/inorganic hybrid composition and structure of the Monorhaphis spicules might provide the blueprint for the synthesis of bio-inspired material, with unusual mechanical properties (strength, stiffness) without losing the exceptional properties of optical transmission.