Collagens of the chicken eggshell membranes

Eggshell membrane as promising supplement to maintain bone health: A systematic review

Bone loss is a well-known phenomenon in the older population leading to increased bone fracture risk, morbidity, and mortality. Supplementation of eggshell membrane (ESM) is evaluated due to its possible application to prevent bone loss and usage in osteoporosis therapy. The similar organic chemical composition of ESM and human bone is described in detail as both mainly consist of collagen type I, chondroitin sulfate, dermatan sulfate, hyaluronic acid and elastan. ESM and its components are reported to improve mineralization in bone tissue. In many studies ESM intake reduced pain in patients with joint disorders and reduced inflammatory processes. Additionally, ESM improved calcium uptake in human cells. These findings in comparison with a clinical pilot study reporting pain reduction in osteoporotic patients and increased osteoblast activity in in vitro assays support ESM to be a beneficial supplement for bone health. In this systematic review we combined chemical structure analysis with clinical studies to give a more comprehensive picture with novel explanations.

Attaching organic fibers to mineral: The case of the avian eggshell

Bird eggs possess a mineralized eggshell with a soft underlying fibrous membrane. These dissimilar material layers successfully evolved a structural attachment to each other as a conserved avian reproduction strategy essential to avian embryonic development, growth, and hatching of the chick. To understand how organic membrane fibers attach to shell mineral (calcite), 3D multiscale imaging including X-ray and electron tomography coupled with deep learning-based feature segmentation was used to show how membrane fibers are organized and anchored into shell mineral. Whole fibers embed into mineral across the microscale, while fine mineral projections (granules/spikes) insert into fiber surfaces at the nanoscale, all of which provides considerable surface area and multiscale anchorage at the organic-inorganic interface between the fibrous membrane and the shell. Such a reciprocal anchorage system occurring at two different length scales between organic fibers and inorganic mineral provides a secure attachment mechanism for avian eggshell integrity across two dissimilar materials.

Apatite-coated outer layer eggshell membrane: A novel osteoinductive biohybrid composite for guided bone/tissue regeneration

Hybrid biomimetic materials aim to replicate the organic-inorganic constructs of mineralized tissues. During eggshell formation, the outer surface of the eggshell membrane (ESM) promotes calcium carbonate nucleation, while the inner one prevents mineralization toward the egg white and yolk. In the current study, the outer surface of the ESM acted as a heteronucleant in calcium phosphate precipitation by the vapor diffusion sitting drop method, while the inner one remained unmineralized. The aim was to fabricate a 2D biomaterial with dual functions, osteoinductive on one side and protective against cell invasion on the other side. The microstructural, physicochemical, morphological, and mechanical properties of the mineralized ESM were characterized by XRD, TGA, XPS, FTIR/Raman, HR-SEM, and mechanical testing techniques. The cytocompatibility and osteoinductive ability were assessed by biological assays of cell viability, proliferation, and osteogenic differentiation on human mesenchymal stromal cells (hMSCs). Results indicate that the outer surface of the ESM induces the heterogeneous precipitation of carbonate-apatite phase depicting biomimetic features. In addition, the apatite/ESM shows a much higher cytocompatibility than the pristine ESM and promotes the osteogenic differentiation of hMSCs more efficiently. Overall, the apatite/ESM composite exhibits compositional, crystalline, mechanical, and biological properties that resemble those of mineralized tissues, rendering it an approachable and novel material especially useful in guided tissue/bone regeneration.

Eggshell Membrane as a Biomaterial for Bone Regeneration

The physicochemical features of the avian eggshell membrane play an essential role in the process of calcium carbonate deposition during shell mineralization, giving rise to a porous mineralized tissue with remarkable mechanical properties and biological functions. The membrane could be useful by itself or as a bi-dimensional scaffold to build future bone-regenerative materials. This review focuses on the biological, physical, and mechanical properties of the eggshell membrane that could be useful for that purpose. Due to its low cost and wide availability as a waste byproduct of the egg processing industry, repurposing the eggshell membrane for bone bio-material manufacturing fulfills the principles of a circular economy. In addition, eggshell membrane particles have has the potential to be used as bio-ink for 3D printing of tailored implantable scaffolds. Herein, a literature review was conducted to ascertain the degree to which the properties of the eggshell membrane satisfy the requirements for the development of bone scaffolds. In principle, it is biocompatible and non-cytotoxic, and induces proliferation and differentiation of different cell types. Moreover, when implanted in animal models, it elicits a mild inflammatory response and displays characteristics of stability and biodegradability. Furthermore, the eggshell membrane possesses a mechanical viscoelastic behavior comparable to other collagen-based systems. Overall, the biological, physical, and mechanical features of the eggshell membrane, which can be further tuned and improved, make this natural polymer suitable as a basic component for developing new bone graft materials.

High-efficiency decomposition of eggshell membrane by a keratinase from Meiothermus taiwanensis

Eggshell membrane (ESM), a plentiful biological waste, consists of collagen-like proteins and glycosaminoglycans (GAGs) such as hyaluronic acid (HA). Here we used a keratinase (oeMtaker)-mediated system to decompose ESM. The best reaction condition was established by incubating the solution containing oeMtaker, sodium sulfite, and ESM with a weight ratio of 1:120:600. ESM enzymatic hydrolysate (ESM-EH) showed a high proportion of essential amino acids and type X collagen peptides with 963–2259 Da molecular weights. The amounts of GAGs and sulfated GAGs in ESM-EH were quantified as 6.4% and 0.7%, respectively. The precipitated polysaccharides with an average molecular weight of 1300–1700 kDa showed an immunomodulatory activity by stimulating pro-inflammatory cytokines (IL-6 and TNF-α) production. In addition, a microorganism-based system was established to hydrolyze ESM by Meiothermus taiwanensis WR-220. The amounts of GAGs and sulfated GAGs in the system were quantified as 0.9% and 0.1%, respectively. Based on our pre-pilot tests, the system shows great promise in developing into a low-cost and high-performance process. These results indicate that the keratinase-mediated system could hydrolyze ESM more efficiently and produce more bioactive substances than ever for therapeutical applications and dietary supplements.

Beneficial effect on rapid skin wound healing through carboxylic acid-treated chicken eggshell membrane

At the initial stage of wound healing, growth factors stimulate tissue regeneration by interacting with the extracellular matrix (ECM), leading to rapid wound repair and structural support. Chicken eggshell membrane (ESM) is a low-cost and highly functional ECM biomaterial for tissue regeneration. However, natural ESM has limitations for tissue engineering purposes because it is difficult to control the size, shape, and biocompatibility of the surfaces. To overcome this, blends of synthetic materials and natural ESMs, such as soluble eggshell membrane protein, are combined for biomaterial applications. Unfortunately, it is difficult to pattern fibrous structure. Here, we modified the natural chicken ESM through weak acid treatment to promote wound healing and skin regeneration without loss of fibrous structure. Treatment of citric acid and acetic acid reacted the amine or amide group with carboxyl groups (R-COOH) and achieved hydrophilicity for adherence of proliferating regenerative cells. Our in vitro study revealed that the modified ESM scaffolds significantly promoted human dermal fibroblasts adhesion, viability, proliferation, and cytokine secretion, compared with natural ESM. In addition, the modified ESM accelerated skin regeneration and enhanced the wound healing process even at early stages in an in vivo rat wound model. Collectively, the modified ESM performed best for promoting skin regeneration, cytokine secretion, epidermal cell proliferation, and controlling the inflammatory response both in vitro and in vivo.

Eggshell membranes coated chitosan decorated with metal nanoparticles for the catalytic reduction of organic contaminates

This study focusses on the effect of chitosan coating with eggshell membranes for the reduction of different organic pollutants. Chickens eggs were collected from the local market and utilized to extract the enrich eggshell membranes (ESM). The chicken eggshell membranes are abundant waste material which is inexpensive and illustrates remarkable physiognomies for many possible applications. Fresh fibers/strips coated by chitosan (CS) were prepared by mixing the eggshell membranes with CS solution (2 wt%/v) in different proportions i.e., 10 %, 30 %, 50 %, 60 %, 70 %, 80 %, and 90 %. These strips were then templated with copper and iron metal nanoparticles by putting them in their metal ions aqueous solution to adsorb the metals ions and were then reduced to zero-valent metal nanoparticles (MNPS) by using NaBH₄ aqueous solution. These prepared materials (MNPS@ESM-CS) were characterized by using XRD, XPS, FE-SEM, and EDS to confirm the successful preparation of MNPs over the surface of ESM coated with CS. Afterwards, these prepared materials were investigated as a catalyst for the reduction of different organic pollutants, such as 4-nitroaniline (4-NA), 4-nitrophenol (4-NP) and methylene blue (MB) dye. The catalytic efficiency of ESM was enhanced 5.7-fold by adding only 20 % CS solution. It was observed that Cu@ESM-CS-80 % took 7 min for reduction of 4-NA, 6 min for 4-NP, and 7 min for MB dye. The reusability of the catalytic strip was also investigated for four cycles and found efficient and can be easily recovered by simply pulling it from the reaction mixture.

Avian eggshell biomineralization: an update on its structure, mineralogy and protein tool kit

BACKGROUND

The avian eggshell is a natural protective envelope that relies on the phenomenon of biomineralization for its formation. The shell is made of calcium carbonate in the form of calcite, which contains hundreds of proteins that interact with the mineral phase controlling its formation and structural organization, and thus determine the mechanical properties of the mature biomaterial. We describe its mineralogy, structure and the regulatory interactions that integrate the mineral and organic constituents during eggshell biomineralization. Main Body. We underline recent evidence for vesicular transfer of amorphous calcium carbonate (ACC), as a new pathway to ensure the active and continuous supply of the ions necessary for shell mineralization. Currently more than 900 proteins and thousands of upregulated transcripts have been identified during chicken eggshell formation. Bioinformatic predictions address their functionality during the biomineralization process. In addition, we describe matrix protein quantification to understand their role during the key spatially- and temporally- regulated events of shell mineralization. Finally, we propose an updated scheme with a global scenario encompassing the mechanisms of avian eggshell mineralization.

CONCLUSION

With this large dataset at hand, it should now be possible to determine specific motifs, domains or proteins and peptide sequences that perform a critical function during avian eggshell biomineralization. The integration of this insight with genomic data (non-synonymous single nucleotide polymorphisms) and precise phenotyping (shell biomechanical parameters) on pure selected lines will lead to consistently better-quality eggshell characteristics for improved food safety. This information will also address the question of how the evolutionary-optimized chicken eggshell matrix proteins affect and regulate calcium carbonate mineralization as a good example of biomimetic and bio-inspired material design.

State-of-the-Art of Eggshell Waste in Materials Science: Recent Advances in Catalysis, Pharmaceutical Applications, and Mechanochemistry

Eggshell waste is among the most abundant waste materials coming from food processing technologies. Despite the unique properties that both its components (eggshell, ES, and eggshell membrane, ESM) possess, it is very often discarded without further use. This review article aims to summarize the recent reports utilizing eggshell waste for very diverse purposes, stressing the need to use a mechanochemical approach to broaden its applications. The most studied field with regards to the potential use of eggshell waste is catalysis. Upon proper treatment, it can be used for turning waste oils into biodiesel and moreover, the catalytic effect of eggshell-based material in organic synthesis is also very beneficial. In inorganic chemistry, the eggshell membrane is very often used as a templating agent for nanoparticles production. Such composites are suitable for application in photocatalysis. These bionanocomposites are also capable of heavy metal ions reduction and can be also used for the ozonation process. The eggshell and its membrane are applicable in electrochemistry as well. Due to the high protein content and the presence of functional groups on the surface, ESM can be easily converted to a high-performance electrode material. Finally, both ES and ESM are suitable for medical applications, as the former can be used as an inexpensive Ca2+ source for the development of medications, particles for drug delivery, organic matrix/mineral nanocomposites as potential tissue scaffolds, food supplements and the latter for the treatment of joint diseases, in reparative medicine and vascular graft producing. For the majority of the above-mentioned applications, the pretreatment of the eggshell waste is necessary. Among other options, the mechanochemical pretreatment has found an inevitable place. Since the publication of the last review paper devoted to the mechanochemical treatment of eggshell waste, a few new works have appeared, which are reviewed here to underline the sustainable character of the proposed methodology. The mechanochemical treatment of eggshell is capable of producing the nanoscale material which can be further used for bioceramics synthesis, dehalogenation processes, wastewater treatment, preparation of hydrophobic filters, lithium-ion batteries, dental materials, and in the building industry as cement.

Polycarboxylated Eggshell Membrane Scaffold as Template for Calcium Carbonate Mineralization

Biomineralization is a process in which specialized cells secrete and deliver inorganic ions into confined spaces limited by organic matrices or scaffolds. Chicken eggshell is the fastest biomineralization system on earth, and therefore, it is a good experimental model for the study of biomineralization. Eggshell mineralization starts on specialized dispersed sites of the soft fibrillar eggshell membranes referred to as negatively charged keratan sulfate mammillae. However, the rest of the fibrillar eggshell membranes never mineralizes, although 21% of their amino acids are acidic. We hypothesized that, relative to the mammillae, the negatively charged amino acids of the fibrillar eggshell membranes are not competitive enough to promote calcite nucleation and growth. To test this hypothesis, we experimentally increased the number of negatively charged carboxylate groups on the eggshell membrane fibers and compared it with in vitro calcite deposition of isolated intact eggshell membranes. We conclude that the addition of poly-carboxylated groups onto eggshell membranes increases the number of surface nucleation sites but not the crystal size.

Removal of Basic Fuchsin from water by using mussel powdered eggshell membrane as novel bioadsorbent: Equilibrium, kinetics, and thermodynamic studies

This study aims to remove organic cationic dye Basic Fuchsin (BF) by adsorption onto a low cost eggshell membrane (ESM) in batch mode at 293 K. XRD analysis confirms the amorphous nature of ESM meanwhile FTIR spectroscopy reveals the presence of several functional groups such as hydroxyl (-OH), sulfhydryl (-SH), carboxyl (-COOH), and amino (-NH₂). Morphological observations by SEM indicate its fibrous microstructure. BET analysis shows a surface area of 11.56 m² g^-1 and the presence of mesopores with a volume of 6.173 10^-3 cm³ g^-1. The value of pH_PZC of ESM is 7.05. The influence of adsorbent dose, contact time, pH, temperature and dye concentration is examined. The highest adsorption capacity around 48 mg.g^-1is achieved for a dye concentration 250 ppm, pH 6 and 25 °C. In addition, adsorption has been found to follow pseudo-second order kinetics. The analysis of the experimental data using linear forms based on Langmuir, Freundlich and Temkin isotherm models indicate that the best fit is obtained with Freundlich model. Thermodynamic parameters (Gibbs free energy, enthalpy, and entropy) reveal that the adsorption of BF onto ESM is an exothermic and spontaneous process. A comprehensive mechanism for BF adsorption by ESM has been proposed.

Fire Protection Performance and Thermal Behavior of Thin Film Intumescent Coating

This paper presents the heat release characteristics, char formation and fire protection performance of thin-film intumescent coatings that integrate eggshell (ES) as an innovative and renewable flame-retardant bio-filler. A cone calorimeter was used to determine the thermal behavior of the samples in the condensed phase in line with the ISO 5660-1 standard. The fire resistance of the coatings was evaluated using a Bunsen burner test to examine the equilibrium temperature and formation of the char layer. The fire propagation test was also conducted according to BS 476: Part 6. On exposure, the samples X, Y, and Z were qualified to be Class 0 materials due to the indexes of fire propagation being below 12. Samples Y and Z reinforced with 3.50 wt.% and 2.50 wt.% of ES bio-filler, respectively, showed a significant improvement in reducing the heat release rate, providing a more uniform and thicker char layer. As a result, the addition of bio-filler content has proven to be efficient in stopping the fire propagation as well as reducing the total heat released and equilibrium temperature of the intumescent coatings.

Bioactive Egg Proteins

The nutritional excellence of chicken egg is derived from its task as a life-giving medium, supplying the necessary nutrients to the hen's embryo while protecting it from external threats. Additionally, egg proteins possess unique biological activities above and beyond their known functional and nutritional roles. In the last few decades, extensive research has been done to evaluate the various biological activities of egg proteins and protein-derived peptides. Egg proteins and protein-derived peptides have been attributed to diverse biological activities, the most well-known being their antimicrobial properties. However, egg proteins and peptides have been shown to have other biological activities, such as antihypertensive, antioxidant, anticancer, immunomodulatory, and protease inhibitory activity. Egg-derived bioactive proteins have had a relevant scientific impact and exhibit promising applicability as an ingredient for the development of functional foods and nutraceuticals. However, it is critical to understand the effects of these proteins in signaling pathways to delineate their molecular mechanisms of action. Further studies are required to fill the current knowledge gaps. Therefore, the purpose of the chapter is to illustrate the present knowledge of the bioactivity of different egg proteins and their physiological effects.

RNA-sequencing analysis of shell gland shows differences in gene expression profile at two time-points of eggshell formation in laying chickens

Background

Eggshell formation takes place in the shell gland of the oviduct of laying hens. The eggshell is rich in calcium and various glycoproteins synthesised in the shell gland. Although studies have identified genes involved in eggshell formation, little is known about the regulation of genes in the shell gland particularly in a temporal manner. The current study investigated the global gene expression profile of the shell gland of laying hens at different time-points of eggshell formation using RNA-Sequencing (RNA-Seq) analysis.

Results

Gene expression profiles of the shell gland tissue at 5 and 15 h time-points were clearly distinct from each other. Out of the 14,334 genes assessed for differential expression in the shell gland tissue, 278 genes were significantly down-regulated (log₂ fold change > 1.5; FDR < 0.05) and 413 genes were significantly up-regulated at 15 h relative to the 5 h time-point of eggshell formation. The down-regulated genes annotated to Gene Ontology (GO) terms showed anion transport, synaptic vesicle localisation, organic anion transport, secretion and signal release as the five most enriched terms. The up-regulated gene annotation showed regulation of phospholipase activities, alanine transport, transmembrane receptor protein tyrosine kinase signalling pathway, regulation of blood vessels diameter and 3, 5-cyclic nucleotide phosphodiesterase activity as the five most enriched GO terms. The putative functions of genes identified ranged from calcium binding to receptor activity. Validation of RNA-Seq results through qPCR showed a positive correlation.

Conclusions

The down-regulated genes at 15 h relative to the 5 h time-point were most likely involved in the transport of molecules and synthesis activities, initiating the formation of the eggshell. The up-regulated genes were most likely involved in calcium transportation, as well as synthesis and secretory activities of ions and molecules, reflecting the peak stage of eggshell formation. The findings in the current study improve our understanding of eggshell formation at the molecular level and provide a foundation for further studies of mRNA and possibly microRNA regulation involved in eggshell formation in the shell gland of laying hens.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5460-4) contains supplementary material, which is available to authorized users.

Solubilized eggshell membrane supplies a type III collagen-rich elastic dermal papilla

Signs of aging in facial skin correlate with lifespan and chronic disease; however, the health of aging skin has not been extensively studied. In healthy young skin, the dermis forms a type III collagen-rich dermal papilla, where capillary vessels supply oxygen and nutrients to basal epidermal cells. Chicken eggshell membranes (ESMs) have been used as traditional medicines to promote skin wound healing in Asian countries for many years. Previously, we designed an experimental system in which human dermal fibroblasts (HDFs) were cultured on a dish with a solubilized ESM (S-ESM) bound to an artificial phosphorylcholine polymer; we found that genes that promoted the health of the papillary dermis, such as those encoding type III collagen, were induced in the S-ESM environment. The present study found that a gel with a ratio of 20% type III/80% type I collagen, similar to that of the baby skin, resulted in a higher elasticity than 100% type I collagen (p < 0.05) and that HDFs in the gel showed high mitochondrial activity. Thus, we decided to perform further evaluations to identify the effects of S-ESM on gene expression in the skin of hairless mice and found a significant increase of type III collagen in S-ESM. Picrosirius Red staining showed that type III collagen significantly increased in the papillary dermis after S-ESM treatment. Moreover, S-ESM application significantly improved human arm elasticity and reduced facial wrinkles. ESMs may have applications in extending lifespan by reducing the loss of tissue elasticity through the increase of type III collagen.

The Influence of Hen Aging on Eggshell Ultrastructure and Shell Mineral Components

The eggshell, which is a complex and highly ordered structure, is very important factor for food safety and egg marketing. This study investigated the changes in eggshell structure and shell components in relationship to hen age. For this study, we examined the histological change of the endometrium of the 30-, 60-, and 72-wk-old commercial layers, and analyzed the ultrastructure and ionic composition of their eggshells. The results showed that histological deformation, fibrosis, atrophy and elimination of micro-villi in the uterus endometrium were found through microscopic observation that was associated with increasing hen age. Concentration of blood-ion components such as Ca2+, Na+, K+, and Cl- ions did not change with age. Along with the results from the ultrastructure analysis of the eggshell, the palisade layer ratio and the density of mammillary knobs were significantly decreased in older hens. In addition, the type B mammillary knobs were frequently observed with increasing hen age. In the mineral element assay from the eggshell, Ca2+, S2-, and Co2+ significantly decreased with increasing hen age, whereas Na+, K+, and V2+ significantly increased. Therefore, the damages of endometrial tissue inhibit the processes of ion transmission and the crystallization of eggshell formation, resulting in a large and non-uniform mammillary knob formation. This means the conditions of endometrial cells affect the formation of the eggshell structure. In conclusion, hen aging causes the weakness of the eggshell and degrades the eggshell quality.

Using Natural Waste Material as a Matrix for the Immobilization of Enzymes: Chicken Eggshell Membrane Powder for β-Galactosidase Immobilization

Avian eggshell membranes are good candidates as a matrix for immobilization procedures. Chicken eggshell, a waste material available from the poultry industry as a byproduct, is a very safe and cheap raw material. While pieces of eggshell membrane, or even particles from whole eggshell, have been previously used for these purposes, we report here the use of eggshell membrane powder for E. coli β-galactosidase immobilization with glutaraldehyde as cross-linker. A kinetic characterization is provided for eggshell membrane powder-bound enzyme compared to free enzyme. Results show a remarkable similarity between bound and free enzyme and also that the immobilized enzyme is stable and can be reused several times. Moreover, bound enzyme is able to produce glucose from skim milk serum.

Ball milling of eggshell waste as a green and sustainable approach: A review

Eggshell waste belongs to the most abundant natural waste in nature and is created in huge amounts by everyday consumption of eggs. The majority of this material is being discarded, despite the fact that it has multidisciplinary applications. In this review, the possibility of utilizing the method of ball milling to further broaden the application potential of this material is discussed. The particular application fields include the formation of nanophases, bioceramics synthesis, formation of composites and preparation of material with increased sorption ability. In addition, some other specific applications, like the utilization of ball-milled eggshell as a drug delivery agent, or for the formation of antibacterially active species, are also mentioned. The review provides a critical mechanochemical insight into this topic and aims to emphasize the green and sustainable way of utilizing eggshell waste by environmentally friendly method.

Beneficial Effects of Oral Supplementation With Ovoderm on Human Skin Physiology: Two Pilot Studies

Collagens and hyaluronic acid have long been used in pharmaceuticals and food supplements for the improvement of skin elasticity and hydration. These compounds provide the building blocks of the skin. Ovoderm is an oral supplement obtained from eggshells that contains naturally occurring collagen and glycosaminoglycans, such as hyaluronic acid. We evaluated the efficacy of Ovoderm on skin biophysical parameters related to cutaneous aging such as elasticity, hydration, and pigmentation. Two pilot studies were run to assess the effect of daily oral supplementation with 300 mg Ovoderm on skin parameters. The first consisted of a self-assessment questionnaire intended to perform an assessment on skin, hair, and nail health after 50 days of treatment. The second measured the effect of 5-week treatment on hydration by corneometry, on elasticity with the cutometer, and on pigmentation with the mexameter. In the pilot study 1, participants were predominantly satisfied with the effects obtained on general face (100% volunteers satisfied) and body (94% volunteers satisfied) skin condition and skin properties (100% volunteers satisfied with facial skin softness, 94% with facial skin hydration, and 89% with body skin hydration) and partly with effects on hair (67% volunteers satisfied) and nail (50% volunteers satisfied) condition. The study 2 revealed a statistically significant improvement in skin elasticity (12% increase, p =.0136), a tendency to reduce skin pigmentation (5% decrease), and no significant change in skin hydration. Our study reflects that oral supplementation with Ovoderm is efficacious to reduce the gradual loss of skin elasticity characteristic of aged skin, which helps to improve the appearance of the skin.

In-depth comparative analysis of the chicken eggshell membrane proteome

The avian eggshell membrane (ESM) is stabilized by extensive cross-linkages, making the identification of its protein constituents technically challenging. Herein, we applied various extraction/solubilization conditions followed by proteomic analysis to characterize the protein constituents of ESM derived from the unfertilized chicken eggs. The egg white and eggshell proteomes (including previous published work) were determined and compared to ESM to identify proteins that are relatively or highly specific to ESM. Merging the results from different extraction/solubilization conditions with various proteomes allowed the identification of 472, 225, and 488 proteins in the ESM, egg white, and eggshell proteomes, respectively. Of these, 163 and 124 proteins were relatively or highly specific to ESM, respectively. GO term analysis of the common proteins and ESM unique proteins generated 8 and 9 significantly enriched functional groups, respectively. Different families of proteins that were identified as ESM-specific included collagens, CREMPs, histones, AvBDs, lysyl oxidase-like 2 (LOXL2), and ovocalyxin-36 (OCX36). These proteins serve as a foundation for the mechanically stable ESM that rests upon the egg white compartment and is a physical barrier against pathogen invasion. Overall, our results highlight the structural nature of the ESM constituents that are relevant to various biomedical applications, such as wound healing.

BIOLOGICAL SIGNIFICANCE

The eggshell membranes (ESM) are a highly resilient double-layered fibrous meshwork that is secreted while the forming egg transits a specialized oviduct segment, the white isthmus. The ESM protects against pathogen invasion and provides a platform for nucleation of the calcitic eggshell (ES). ESM is greatly stabilized by the extensive desmosine, isodesmosine and disulfide cross-linkages which make the identification of its protein constituents by standard proteomic approaches technically challenging. Comparative proteomic analyses of ESM, egg white, and ES proteins showed proteins groups that are relatively or highly specific to ESM. These groups of proteins serve as a foundation for the mechanically stable ESM that rests upon the egg white compartment and is a physical barrier against pathogen invasion. These features are essential for eggshell quality and for the prevention of pathogen invasion which reinforce food safety of the table egg.

Is the snail shell repair process really influenced by eggshell membrane as a template of foreign scaffold?

Biominerals are inorganic-organic hybrid composites formed via self-assembled bottom up processes under mild conditions. Biominerals show interesting physical properties, controlled hierarchical structures and robust remodeling or repair mechanisms. Biological processes associated with biominerals remain to be developed into practical engineering processes. Therefore, the formation of biominerals is inspiring for the design of materials, especially those fabricated at ambient temperatures. The study described herein involves the influence of chicken outer eggshell membrane on the type of calcium carbonate (CaCO₃) polymorph deposited on the shell of the land snail Helix aspersa during the repair process after an injury. A piece of snail shell was removed by perforating a hole from the largest body whorl. The operated area was left either uncovered or covered with either a thermoplastic flexible polyolefin-based film Parafilm® or a piece of chicken eggshell membrane. The repaired shells of control and experimental animals were analyzed using SEM, EDS, Raman and FTIR spectroscopies. We found that in the presence of eggshell membrane, the polymorph deposited on the substratum during the first hours resembles calcite, the polymorph present in eggshell normal formation, but at 24 and 48h, when snail mantle cells produced their normal organic matrix (mainly β-chitin plus proteins and proteoglycans), the polymorph deposited is aragonite, the characteristic polymorph of Helix shell. Therefore, the eggshell membrane influences the type of polymorph, but only in the initial stages of biomineral deposition, before an organic matrix layer is deposited by the snail.

Characteristics of glycosaminoglycans in chicken eggshells and the influence of disaccharide composition on eggshell properties

Glycosaminoglycans (GAG) are linear, highly negatively charged polysaccharides that may perform an important role in biomineralization. GAG were isolated from chicken eggshell membranes and calcified shells. Disaccharide compositional analysis was performed using liquid chromatography-mass spectrometry. All 4 groups of GAG - hyaluronan (HA), keratan sulfate (KS), chondroitin sulfate (CS), and heparan sulfate (HS) - were detected in shell membranes and in calcified shells. HA was the most plentiful GAG in shell membranes, and CS was the most abundant in calcified shells. The CS present, in both membranes and calcified shells, consisted primarily of 6S_CS-C, 4S_CS-A, and 0S_CS-0 disaccharides. Neither 4S6S_CS-E nor 2S_CS was detectable in shell components. Small amounts of 2S4S_CS-B were detected in membranes and TriS_CS, and 2S4S_CS-B and 2S6S_CS-D were detected in calcified shells. HS in calcified shells contained all disaccharides except for 2S6S. In shell membranes, HS contained primarily NS and 0S as well as small amounts of TriS, NS2S, NS6S_HS, and 6S, but neither 2S6S nor 2S was detectable. The disaccharide composition of membrane CS, as well as membrane and calcified shell HS, were very similar in all eggshells. In contrast, the composition of calcified shell CS disaccharides was highly variable. In membranes, both HA and KS content showed a correlation with egg shape index. The 4S_CS-A content correlated with eggshell strength, and 0S_CS-0 correlated with eggshell strength and calcified shell thickness. HS content and its disaccharide composition showed no apparent correlation to properties of calcified shells. In calcified shells, only HS 6S correlated with egg shape index. This study suggests that GAG content and disaccharide composition of shell membranes might impact the quality of chicken eggshells.

Identifying specific proteins involved in eggshell membrane formation using gene expression analysis and bioinformatics

Background

The avian eggshell membranes surround the egg white and provide a structural foundation for calcification of the eggshell which is essential for avian reproduction; moreover, it is also a natural biomaterial with many potential industrial and biomedical applications. Due to the insoluble and stable nature of the eggshell membrane fibres, their formation and protein constituents remain poorly characterized. The purpose of this study was to identify genes encoding eggshell membrane proteins, particularly those responsible for its structural features, by analyzing the transcriptome of the white isthmus segment of the oviduct, which is the specialized region responsible for the fabrication of the membrane fibres.

Results

The Del-Mar 14 K chicken microarray was used to investigate up-regulated expression of transcripts in the white isthmus (WI) compared with the adjacent magnum (Ma) and uterine (Ut) segments of the hen oviduct. Analysis revealed 135 clones hybridizing to over-expressed transcripts (WI/Ma + WI/Ut), and corresponding to 107 NCBI annotated non-redundant Gallus gallus gene IDs. This combined analysis revealed that the structural proteins highly over-expressed in the white isthmus include collagen X (COL10A1), fibrillin-1 (FBN1) and cysteine rich eggshell membrane protein (CREMP). These results validate previous proteomics studies which have identified collagen X (α-1) and CREMP in soluble eggshell extracts. Genes encoding collagen-processing enzymes such as lysyl oxidase homologs 1, 2 and 3 (LOXL1, LOXL2 and LOXL3), prolyl 4 hydroxylase subunit α-2 and beta polypeptide (P4HA2 and P4HB) as well as peptidyl-prolyl cis-trans isomerase C (PPIC) were also over-expressed. Additionally, genes encoding proteins known to regulate disulfide cross-linking, including sulfhydryl oxidase (QSOX1) and thioredoxin (TXN), were identified which suggests that coordinated up-regulation of genes in the white isthmus is associated with eggshell membrane fibre formation.

Conclusions

The present study has identified genes associated with the processing of collagen, other structural proteins, and disulfide-mediated cross-linking during eggshell membrane formation in the white isthmus. Identification of these genes will provide new insight into eggshell membrane structure and mechanisms of formation that will assist in the development of selection strategies to improve eggshell quality and food safety of the table egg.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2013-3) contains supplementary material, which is available to authorized users.

Dietary calcium deficiency in laying ducks impairs eggshell quality by suppressing the process of shell biomineralization

The objective of this study was to determine the effects of dietary calcium deficiency on the process of shell formation. Four hundred and fifty female ducks (Anas platyrhynchos) of 22 wk were randomly assigned to 3 groups. Ducks were fed one of two calcium-deficient diets (containing 1.8% or 0.38% calcium, respectively) or a calcium-adequate control diet (containing 3.6% calcium) for 67 d (depletion period), and then ducks of the 3 groups were fed a calcium-adequate diet for an additional 67 d (repletion period). As compared with the calcium-adequate control, the average shell thickness, egg shell weight, breaking strength, mammillae density and mammillary knob thickness of shell from ducks that consumed the diet with 0.38% calcium was significantly decreased (P&lt;0.05) during the depletion period, accompanied by reduced quality of shell and tibia. The mRNA expression of both secreted phosphoprotein 1 (SPP1) and carbonic anhydrase 2 (CA2) in uterus were decreased after feeding calcium-deficient diets (1.8% or 0.38% calcium). Transcripts of calbindin 1 (CALB1), an important protein responsible for calcium transport, and matrix protein gene ovocalyxin-32 (OCX-32) and ovocleidin-116 (OC-116) were reduced in the ducks fed 0.38% calcium but not the 1.8% calcium. Plasma estradiol concentration was decreased by both of the calcium-deficient diets (P&lt;0.05). The impaired shell quality and suppressed functional proteins involved in shell formation could be reversed by repletion of dietary calcium. The results of the present study suggest that dietary calcium deficiency negatively affects the eggshell quality and eggshell microarchitecture probably through suppressing the process of shell biomineralization.

Water soluble blue-emitting AuAg alloy nanoparticles and fluorescent solid platforms for removal of dyes from water

We report here the successful formation of blue-emitting AuAg alloy nanoparticles and a solid fluorescent platform by a biotemplate-induced reduction process using egg shell membrane, and the applications of the nanoparticles.

Eggshell membrane biomaterial as a platform for applications in materials science

Eggshell membrane (ESM) is a unique biomaterial, which is generally considered as waste. However, it has extraordinary properties which can be utilized in various fields and its potential applications are therefore now being widely studied. The first part of this review focuses on the chemical composition and morphology of ESM. The main areas of ESM application are discussed in the second part. These applications include its utilization as a biotemplate for the synthesis of nanoparticles; as a sorbent of heavy metals, organics, dyes, sulfonates and fluorides; as the main component of biosensors; in medicine; and various other applications. For each area of interest, a detailed literature survey is given.

Sorption on eggshell waste--a review on ultrastructure, biomineralization and other applications

The structure, adsorption behavior and applications of eggshell waste materials have been reviewed. The ultrastructure of eggshell particles has been discussed to understand the pore structure as well as the surface geometry of the materials leading to its multifarious applicability. Besides, the ultrastructure studies give full information regarding the chemical constituents of egghell particles as well as eggshell membranes. The process of biomineralization in living organisms, their consequent effect of controlling the formation of inorganic-organic composites propelling their application in biomimetic designing of advanced composites with optimized novel properties leading to advances in materials design have been discussed. Utilization of eggshell waste materials for the removal of organic dyes and heavy inorganic ions has been reviewed with suitable models for understanding their adsorption quality and capacity. The applications of these materials in various fields of research have been extensively discussed.

Ovocalyxin-36 is a pattern recognition protein in chicken eggshell membranes

The avian eggshell membranes are essential elements in the fabrication of the calcified shell as a defense against bacterial penetration. Ovocalyxin-36 (OCX-36) is an abundant avian eggshell membrane protein, which shares protein sequence homology to bactericidal permeability-increasing protein (BPI), lipopolysaccharide-binding protein (LBP) and palate, lung and nasal epithelium clone (PLUNC) proteins. We have developed an efficient method to extract OCX-36 from chicken eggshell membranes for purification with cation and anion exchange chromatographies. Purified OCX-36 protein exhibited lipopolysaccharide (LPS) binding activity and bound lipopolysaccharide (LPS) from Escherichia coli O111:B4 in a dose-dependent manner. OCX-36 showed inhibitory activity against growth of Staphylococcus aureus ATCC 6538. OCX-36 single nucleotide polymorphisms (SNPs) were verified at cDNA 211 position and the corresponding proteins proline-71 (Pro-71) or serine-71 (Ser-71) were purified from eggs collected from genotyped hens. A significant difference between Pro-71 and Ser-71 OCX-36 for S. aureus lipoteichoic acid (LTA) binding activity was detected. The current study is a starting point to understand the innate immune role that OCX-36 may play in protection against bacterial invasion of both embryonated eggs (relevant to avian reproductive success) and unfertilized table eggs (relevant to food safety).

Solubilization and identification of hen eggshell membrane proteins during different times of chicken embryo development using the proteomic approach

A fertilized chicken egg is a unit of life. During hatching, transport of nutrients, including calcium, have been reported from the egg components to the developing embryo. Calcium is mobilized from the eggshell with the involvement of Ca(2+)-binding proteins. In addition, other unknown proteins may also play some important roles during embryo developing process. Therefore identification and prediction of biological functions of eggshell membrane (ESM) proteins during chick embryo development was conducted by proteome analysis. Comparison of different lysis solutions indicated that the highest ability to extract ESM proteins could be obtained with 1 % sodium dodecyl sulfate in 5 mM Tris-HCl buffer pH 8.8 containing 0.1 % 2-mercaptoethanol. In this study fertilized Cornish chicken eggs were incubated at 37 °C in humidified incubators for up to 21 days. At selected times (days 1, 9, 15 and 21), samples were taken and the ESMs were carefully separated by hand, washed with distilled water, and air-dried at room temperature. The ESM proteins were then solubilized and analyzed by proteome analysis. Sodium dodecyl sulfate polyacrylamide gel electrophoresis combined with high performance liquid chromatography and mass spectrometry revealed 62 proteins in the ESM; only keratin is known ESM protein, 8 of which are egg white proteins and related while 53 others have not previously been reported. Some differences in the types of proteins and their molecular functions were noted in ESM at different incubation times. One protein which was present only at days 15 and 21 of egg incubation was identified as a calcium binding protein i.e. EGF like repeats and discoidin I like domain 3 (EDIL3 homologous protein).

Increased collagen accumulation in eggshell membrane after feeding with dietary wood charcoal powder and vinegar

Collagen in an eggshell membrane is important for egg preservation, medical burn treatment and manufacturing of cosmetics. Because collagen in the membrane is little, it is a need to improve the accumulation in the membrane to develop these applications. Wood charcoal powder with vinegar (WCV) is a natural substance that improves poultry production. In hen fed with WCV, total collagen in the eggshell membrane increased with an increase in dietary WCV and significantly increased in the 1.0% WCV group (p < 0.05). Scanning and light microscopic images revealed that this group had thicker eggshell membranes and a fine mesh structure composed of finer and more densely distributed fibres than in the control. Eggs from WCV group showed slow Haugh unit decrease during egg storage and the decrease correlated with total collagen in eggshell membrane. In intact chicken, type I and type III collagens were found in different specific locations in the oviduct but not in the membrane. The finding that collagen accumulates in the eggshell membrane under WCV feeding suggests that feeding chicken with WCV will permit long-term storage of eggs in poultry production, and the increased volume of total collagen will facilitate its application in medicine and cosmetics.

Remineralization of partially demineralized dentine substrate based on a biomimetic strategy

Dentine remineralization is clinically significant for prevention and treatment of dentine caries, root caries, and dentine hypersensitivity. However, dentine remineralization is more difficult than enamel remineralization due to the abundant presence of organic matrix in dentine. The objective of this study was to develop a biomimetic method to facilitate remineralization of demineralized dentine through phosphorylation of type I collagen in demineralized dentine using sodium trimetaphosphate. The experimental results indicated that the effect of fluoride on remineralizing dentine was limited when residual mineral crystals were lacking on the surface of demineralized dentine, whereas the phosphorylation and Ca(OH)(2) pretreatment enhanced surface remineralization of the partially demineralized dentine. This biomimetic methodology resulted in favorable surface properties (i.e. highly negative charge and low interfacial free energy between substrate and aqueous medium) for crystal nucleation, and thus could be a promising method to remineralize superficially demineralized dentine lesions.

Identification of genes directly involved in shell formation and their functions in pearl oyster, Pinctada fucata

Mollusk shell formation is a fascinating aspect of biomineralization research. Shell matrix proteins play crucial roles in the control of calcium carbonate crystallization during shell formation in the pearl oyster, Pinctada fucata. Characterization of biomineralization-related genes during larval development could enhance our understanding of shell formation. Genes involved in shell biomineralization were isolated by constructing three suppression subtractive hybridization (SSH) libraries that represented genes expressed at key points during larval shell formation. A total of 2,923 ESTs from these libraries were sequenced and gave 990 unigenes. Unigenes coding for secreted proteins and proteins with tandem-arranged repeat units were screened in the three SSH libraries. A set of sequences coding for genes involved in shell formation was obtained. RT-PCR and in situ hybridization assays were carried out on five genes to investigate their spatial expression in several tissues, especially the mantle tissue. They all showed a different expression pattern from known biomineralization-related genes. Inhibition of the five genes by RNA interference resulted in different defects of the nacreous layer, indicating that they all were involved in aragonite crystallization. Intriguingly, one gene (UD_Cluster94.seq.Singlet1) was restricted to the ‘aragonitic line’. The current data has yielded for the first time, to our knowledge, a suite of biomineralization-related genes active during the developmental stages of P.fucata, five of which were responsible for nacreous layer formation. This provides a useful starting point for isolating new genes involved in shell formation. The effects of genes on the formation of the ‘aragonitic line’, and other areas of the nacreous layer, suggests a different control mechanism for aragonite crystallization initiation from that of mature aragonite growth.