Chondroitin sulfate and hydroxyapatite from Prionace glauca shark jaw: Physicochemical and structural characterization

In the present work, the potential of the Prionace glauca jaw as a source of both chondroitin sulfate and bioapatite is explored. The sandwich-type structure in cross section of the jaw based on alternate layers with prevalence in organic tissue or mineralized is shown and these bands respectively confirmed as CS or hydroxyapatite -enriched zones. As result of this, an optimized process in sequential steps for the recovery of both biomaterials and their purification process is proposed, by combining enzymatic proteolysis, chemical precipitation and separation using ultrafiltration membrane for CS production together with controlled thermal treatment for hydroxyapatite obtaining. The purified CS was characterized by Gel Permeation Chromatography, Nuclear Magnetic Resonance and Strong Anion Exchange Chromatography, revealing a polymeric material with a molecular weight of 67 kDa, and prevalent 6S-GalNAc sulfation (68%), followed by 4S-GalNAc (13%), a significant proportion of disulfated disaccharides (12%) and only 7% of non-sulfated units. In the case of the bioapatite a purified biphasic 60:40 porous calcium phosphate of hydroxyapatite: whitlockite/β-TCP was confirmed. Hydroxyapatite as major component (85%) was also obtained for jaws directly subjected to the thermal treatment. This proved the influence of the enzymatic hydrolysis and centrifugation on the composition of the mineral fraction.

Ion Effect and Metal-Coordinated Cross-Linking for Multiscale Design of Nereis Jaw Inspired Mechanomutable Materials

The Nvjp-1 protein is a key component in the jaws of Nereis virens, a species of marine worm. It contains over 25 mol % of histidine, which is believed to play a key role in the metal-coordinated cross-linking responsible for the structural stability and exceptional mechanical performance of the worm jaw. Understanding the nanoscale mechanism behind this cross-linking and its pathway in affecting the macroscopic mechanical behavior of the material is crucial to develop bioinspired mechanomutable materials based on Nvjp-1. Here, we use a combination of multiscale modeling and experimental synthesis to understand the behavior of this heterologous-expressed protein from the nano- to the macroscale. We have built a bottom-up molecular-based model, which includes electronic-based density functional theory calculations, atomistic simulation of the nanoscale properties with replica exchange molecular dynamics, and an elastic network model for describing the macroscale behavior at different pHs. This multiscale modeling supports the experimental synthesis of a photo-cross-linked Nvjp-1 hydrogel by proving both the nanoscale mechanisms and mechanical behavior predictions. Our theoretical results agree well with the experimental observations, showing that Nvjp-1 forms a more compact structure in the presence of Zn²⁺ ions with a suitable pH environment, leading to the formation of more stable intramolecular metal-coordinated cross-links. These metal-coordinated cross-links induce nanoscale aggregation of Nvjp-1, which is responsible for the hydrogel contraction observed in experiments and predicted by the model.

Elements and elasmobranchs: hypotheses, assumptions and limitations of elemental analysis

Quantifying the elemental composition of elasmobranch calcified cartilage (hard parts) has the potential to answer a range of ecological and biological questions, at both the individual and population level. Few studies, however, have employed elemental analyses of elasmobranch hard parts. This paper provides an overview of the range of applications of elemental analysis in elasmobranchs, discussing the assumptions and potential limitations in cartilaginous fishes. It also reviews the available information on biotic and abiotic factors influencing patterns of elemental incorporation into hard parts of elasmobranchs and provides some comparative elemental assays and mapping in an attempt to fill knowledge gaps. Directions for future experimental research are highlighted to better understand fundamental elemental dynamics in elasmobranch hard parts.

A new approach for the determination of ammonite and nautilid habitats

Externally shelled cephalopods were important elements in open marine habitats throughout Earth history. Paleotemperatures calculated on the basis of the oxygen isotope composition of their shells can provide insights into ancient marine systems as well as the ecology of this important group of organisms. In some sedimentary deposits, however, the aragonitic shell of the ammonite or nautilid is poorly or not preserved at all, while the calcitic structures belonging to the jaws are present. This study tests for the first time if the calcitic jaw structures in fossil cephalopods can be used as a proxy for paleotemperature. We first analyzed the calcitic structures on the jaws of Recent Nautilus and compared the calculated temperatures of precipitation with those from the aragonitic shell in the same individuals. Our results indicate that the jaws of Recent Nautilus are secreted in isotopic equilibrium, and the calculated temperatures approximately match those of the shell. We then extended our study to ammonites from the Upper Cretaceous (Campanian) Pierre Shale of the U.S. Western Interior and the age-equivalent Mooreville Chalk of the Gulf Coastal Plain. In the Pierre Shale, jaws occur in situ inside the body chambers of well-preserved Baculites while in the Mooreville Chalk, the jaw elements appear as isolated occurrences in the sediment and the aragonitic shell material is not preserved. For the Pierre Shale specimens, the calculated temperatures of well-preserved jaw material match those of well-preserved shell material in the same individual. Analyses of the jaw elements in the Mooreville Chalk permit a comparison of the paleotemperatures between the two sites, and show that the Western Interior is warmer than the Gulf Coast at that time. In summary, our data indicate that the calcitic jaw elements of cephalopods can provide a reliable geochemical archive of the habitat of fossil forms.

Benign odontogenic tumors versus histochemically related tissues: preliminary results from mid-infrared and solid-state nuclear magnetic resonance spectroscopy

Three types of human odontogenic tumors histologically classified as compound composite odontoma, ossifying fibroma, and Pindborg tumor were characterized using mid-infrared spectroscopy (mid-IR) and solid-state nuclear magnetic resonance (ssNMR). For comparison, human jawbone and dental mineralized tissues such as dentin, enamel, and dental cement were also characterized. The studies focused on the structural properties and chemical composition of pathological tissues versus histochemically related tissues. All analyzed tumors were composed of organic and mineral parts and water. Apatite was found to be the main constituent of the mineral part. Various components (water, structural hydroxyl groups, carbonate ions (CO(3)(2-)), and hydrogen phosphate ions (HPO(4)(2-))) and physicochemical parameters (index of apatite maturity and crystallinity) were examined. The highest organic/mineral ratio was observed in fibrocementoma, a finding that can be explained by the fibrous character of the tumor. The lowest relative HPO(4)(2-) content was found in odontoma. This tumor is characterized by the highest mineral crystallinity index and content of structural hydroxyl groups. The Pindborg tumor mineral portion was found to be poorly crystalline and rich in HPO(4)(2-). The relative CO(3)(2-) content was similar in all samples studied. The results of spectroscopic studies of odontogenic tumors were consistent with the standard histochemical analysis. It was shown that the various techniques of ssNMR and elaborate analysis of the mid-IR spectra, applied together, provide valuable information about calcified benign odontogenic tumors.

Toxic and essential metal concentrations in four tissues of red deer (Cervus elaphus) from Baranja, Croatia

Kidney (n = 297), liver (n = 52), jawbone (n = 80) and muscle (n = 48) samples collected from red deer (Cervus elaphus) from north-eastern Croatia in the 2002--05 hunting season were analysed for cadmium (Cd), copper (Cu), iron (Fe), mercury (Hg), lead (Pb), selenium (Se) and zinc (Zn) using atomic absorption spectrometry. Statistical evaluation of results showed age-related accumulations of renal cortex Cd and Zn, bone Pb, and muscle Zn. Renal cortex Cd and Zn were significantly associated. In addition, concentrations of Cd and Pb in muscle tissue were significantly correlated with Fe content. Found levels of toxic metals were not likely to affect the health status of animals. A total of 49% of the muscle, 60% of the kidney and 6% of the liver samples were unsuitable for human consumption according to Croatian regulations for Cd in food. However, the calculated intake of Cd through deer meat consumption is small and represents no health risk when consumption is moderate.

Biochemical characterization of collagen in alveolar mucosa and attached gingiva of pig

Alveolar mucosa and attached gingiva are two continuous but functionally distinct connective tissues covering alveolar bone of the jaw. In this study, the major matrix component of these tissues, collagen, was biochemically characterized and compared. The tissues were obtained from mature pigs and analyzed for collagen content, amino acid composition, collagen types, collagen cross-linking, and gene expression. We found that alveolar mucosa is primarily composed of fibrillar collagens and the collagen content is higher than attached gingiva. The content of type III relative to type I collagen was higher in alveolar mucosa when compared with attached gingiva. The collagen cross-linking pattern also was distinct between the two tissues demonstrating that alveolar mucosa contained fewer reducible cross-links but more non-reducible cross-links in comparison to attached gingiva. The mRNA expression level of type I collagen in alveolar mucosa was significantly lower than that of attached gingiva. These results indicate that alveolar mucosa is a fibrillar collagen-rich tissue and, in comparison to gingival tissue, re-models slowly.

Critical role of zinc in hardening of Nereis jaws

Hardening of invertebrate jaws and mandibles has been previously correlated to diverse, potentially complex modifications. Here we demonstrate directly, for the first time, that Zn plays a critical role in the mechanical properties of histidine-rich Nereis jaws. Using nanoindentation, we show that removal of Zn by chelation decreases both hardness and modulus by over 65%. Moreover, reconstitution of Zn yields a substantial recovery of initial properties. Modulus and hardness of Zn-replete jaws exceed those attainable by current engineering polymers by a factor of >3. Zn-mediated histidine cross-links are proposed to account for this enhancement in mechanical properties.

Halogenated veneers: protein cross-linking and halogenation in the jaws of nereis, a marine polychaete worm

Mineralized tissues are produced by most living organisms for load and impact functions. In contrast, the jaws of the clam worm, Nereis, are hard without mineralization. However, they are peculiarly rich in halogens, which are associated with a variety of post-translationally modified amino acids, many of which are multiply halogenated by chlorine, bromine, and/or iodine. Several of these modified amino acids, namely dibromohistidine, bromoiodohistidine, chloroiodotyrosine, bromoiodotyrosine, chlorodityrosine, chlorotrityrosine, chlorobromotrityrosine, and bromoiodotrityrosine, have not been previously reported. We have found that the distributions of Cl, Br, and I differ: Cl is widespread whereas Br and I, although not colocalized, are concentrated in proximity to the external jaw surfaces. By using nanoindentation, we show that Br and I are unlikely to play a purely mechanical role, but that the local Zn and Cl concentrations and jaw microstructure are the prime determinants of local jaw hardness. Several of the post-translationally modified amino acids are akin to those found in various sclerotized structures of invertebrates, and we propose that they are part of a cross-linked protein casing.

Melanin and Glycera jaws: emerging dark side of a robust biocomposite structure

Defining the design principles guiding the fabrication of superior biocomposite structures from an assemblage of ordinary molecules is a key goal of biomimetics. Considering their low degree of mineralization, Glycera jaws have been shown to be extraordinarily resistant to abrasion based on the metric hardness3/Young's modulus2. The jaws also exhibit an impressive chemical inertness withstanding boiling concentrated hydrochloric acid as well as boiling concentrated sodium hydroxide. A major organic component largely responsible for the chemical inertness of the jaws has been characterized using a spectrophotometric assay for melanin content, 13C solid state nuclear magnetic resonance, IR spectroscopy, and laser desorption ionization-time of flight mass spectrometry and is identified here as a melanin-like network. Although melanin is widely distributed as a pigment in tissues and other structural biomaterials, to our knowledge, Glycera jaws represent the first known integument to exploit melanin as a cohesive load- and shape-bearing material.

Heavy metal levels in tissues of red deer (Cervus elaphus) from Eastern Croatia

The aim of this study was to measure the levels of some toxic and essential metals in the kidney cortex and jawbone of red deer caught in Baranja region, Eastern Croatia. Kidneys and jawbones of 57 red deer (17 males, 40 females), aged six months to ten years, were collected and the concentrations of metals determined using atomic absorption spectrometry (AAS). The median mass fraction of toxic cadmium, mercury, and lead in the kidney were 0.099 mg kg(-1), 0.362 mg kg(-1), and 0.578 mg kg(-1) (wet weight), respectively. In the jawbone, the Pb mass fraction was 0.281 mg kg(-1). The median levels of essential elements in the kidney were 35.1 mg kg(-1) for Zn, 5.20 mg kg(-1) for Cu, and 108 mg kg(-1) for Fe. The mass fraction of Zn in the jawbone was 86.8 mg kg(-1). Statistical analysis showed age-related differences in the accumulation of Pb in both tissues and of Cd in the kidney. Kidney Zn and Fe also increased with age. Toxic metal levels in the kidney exceeded the levels considered acceptable for human consumption, especially in older animals.

Effect of hyper or hypo-osmotic conditions on neutral amino acid uptake and oxidation in tissues of the crab Chasmagnathus granulata

We investigated the transport of (14)C-methylaminoisobutyric acid ((14)C-MeAIB) and (14)C-alanine oxidation in hepatopancreas and jaw muscle of Chasmagnathus granulata submitted to 24, 72, and 144 h of hypo- or hyperosmotic stress. While (14)C-MeAIB uptake increased in jaw muscle and hepatopancreas from crabs submitted to hyperosmotic stress, it did not change in tissues from animals submitted to hypo-osmotic stress. Incubation of jaw muscle and hepatopancreas from control groups with 1 mM ouabain did not decrease (14)C-MeAIB uptake. However, ouabain prevented (14)C-MeAIB uptake in hepatopancreas at 24 h of hyperosmotic stress. In contrast, in jaw muscle from crabs submitted to the same conditions, (14)C-MeAIB uptake was not prevented by ouabain in the incubation medium. Jaw muscle from the control group produced four times more (14)CO(2) from (14)C-alanine than the hepatopancreas. During hypo-osmotic stress, amino acid oxidation does not seem to be one of the pathways implicated in the decrease of the amino acid pools in hepatopancreas and jaw muscle. In contrast, during hyperosmotic stress the reduction in (14)C-alanine oxidation appears to be one of the mechanisms involved in the increase of the amino acid pool in the hepatopancreas.

[Effect of cariesogenic diet and age on selenium distribution between blood and mineralized tissues in rats]

The distribution of Se in the blood and teeth (in the jaw and femoral bones) was evaluated using a new coefficient of relative radioactivity (RRA), representing the ratio of (75)Se in the teeth (bones) and blood. Changes in all RRA were studied during 1-192 hours after intraperitoneal injection of [(75)Se]selenate in one-month-old rats receiving common fodder; a biphasic pattern of changes was observed, with peaks 6 and 48 h and lowering 24 and 192 h postinjection. The first peak was mainly due to Se adsorption on hydroxyapatite, the second to chemo-adsorption on it and Se binding to protein. In 3-month-old rats receiving common fodder the peak of all RRA was delayed to 12-48 h postinjection, the values decreasing by 192 h. The peak of specific activity (SA) of (75)Se protein in the bones was recorded 24 h and its decrease 192 h postinjection. In one-month-old rats receiving sucrose-casein diet during 2 months all RRA and SA after 6 and 12 h and part of RRA after 24 h were higher than in the control, that is, Se absorption by bones and teeth from the blood decreased.

Jaw bone remodeling at the invasion front of gingival squamous cell carcinomas

BACKGROUND

It is still unknown how jaw bone remodeling occurs at actual invasion sites of oral squamous cell carcinomas. Since there is no other human carcinomas which make a direct invasion of the bone, gingival carcinomas are valuable examples.

METHODS

Twelve surgical specimens of gingival squamous cell carcinoma were examined histopathologically and immunohistochemically for remodeling of bone and its surrounding tissue.

RESULTS

Three types of bone interfaces with carcinomatous invasion were distinguished. These included areas with bone resorption, smooth bone surface and new bone formation. In the bone-resorption area, numerous osteoclasts were located along the bone surface, which was surrounded by myxoid stroma. The myxoid stroma was characterized by immunopositivity for heparan sulfate proteoglycan (HSPG), abundant vascularity and macrophagic infiltration. In the bone-formation area, rows of osteoblasts were aligned on the bone surface. The stroma around osteoblasts was also HSPG-immunopositive, poor in vascularity but rich in activated fibroblasts. In the smooth-bone area, the stroma showed an organizing phase of granulation tissue with slender fibroblasts and mature collagen fibers but with less vascularity and inflammatory infiltrates.

CONCLUSION

The results indicate that the stromal architecture, especially in terms of its inflammatory cellular, vascular and matrix compositions, is strictly regulated in the timing and site of jaw bone remodeling which is causes by carcinomatous invasion.

High abrasion resistance with sparse mineralization: copper biomineral in worm jaws

Biominerals are widely exploited to harden or stiffen tissues in living organisms, with calcium-, silicon-, and iron-based minerals being most common. In notable contrast, the jaws of the marine bloodworm Glycera dibranchiata contain the copper-based biomineral atacamite [Cu2(OH)3Cl]. Polycrystalline fibers are oriented with the outer contour of the jaw. Using nanoindentation, we show that the mineral has a structural role and enhances hardness and stiffness. Despite the low degree of mineralization, bloodworm jaws exhibit an extraordinary resistance to abrasion, significantly exceeding that of vertebrate dentin and approaching that of tooth enamel.

Ultrastructural localization and biochemical characterization of vitronectin in developing rat bone

This study has used light and electron microscope immunohistochemical and biochemical methods to localize and characterize vitronectin in early bone formation of developing rat mandible with rabbit antimurine vitronectin IgG. Developing jaws of foetuses were collected at embryonic day 15 (day 15) to day 18 from pregnant Wistar rats. After aldehyde fixation, specimens with and without osmium post-fixation were dehydrated and embedded in paraffin, Spurr's resin or LR gold resin for morphological and immunohistochemical examinations. At the light microscope level, in day 15 samples, positive vitronectin immunostaining was observed in small elongated areas of intercellular matrix and osteoblasts. Concomitant with initiation of matrix mineralization at day 16, vitronectin staining was similarly observed in small elongated areas containing intercellular matrix and osteoblasts but not clearly detected in fully mineralized bone matrix. The same staining profile was observed at days 17 and 18. At the ultrastructural level, immunogold particles were clearly detected over unmineralized matrix and cisterns of the rough-surfaced endoplasmic reticulum and the Golgi apparatus of osteoblasts as well as over demineralized bone matrix at day 16-18. In order to assess the presence of vitronectin in the mineral phase, mineral-binding bone proteins were extracted from fresh day 18 specimens using a three-step technique: 4M guanidine HCl (G1 extract), aqueous EDTA without guanidine HCl (E extract), followed by guanidine HCl. Subsequent Western blot analysis of sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis revealed that the antibodies produced only a single band at an M(r) of approximately 73000 in both G1 and E extracts, indicating the presence of vitronectin in the mineralized bone matrix. These results indicate that, at the onset of bone formation, osteoblasts synthesize and release vitronectin, which is subsequently incorporated into the bone matrix and becomes a specific component of bone tissues. The observation of vitronectin in these critical stages of bone formation suggests that it may be involved in the regulation of bone formation.

Identification and localization of endothelin-1 and its receptors in human fetal jaws

In the mouse, disruption of the endothelin-1 (ET-1) gene causes severe craniofacial deformities, including mandibular hypoplasia. Since the phenotype of ET-1-deficient mice shows features in common with inherited human mandibulofacial dysostosis, we investigated the presence of ET-1 and its receptors in human fetal craniofacial tissues of 9- to 12-week-old fetuses. We found that ET-1 is immunolocalized in the epithelial cells of the oral cavity. Radioligand binding studies indicate the presence of elevated concentrations of both ETA and ETB receptors in membranes derived from fetal jaws. Using autoradiography, 125I-ET-1 binding sites were shown to be localized within the embryonic mandibular process of the oral cavity, where they were confined to the mesenchymal-derived osteogenic cells. Our data suggest a role for ET-1 in the development of the human mandible.