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

Mechanical design principles of avian eggshells for survivability

Biological materials exhibit complex structure-property relationships which are designed by nature's evolution over millions of years. Unlocking the fundamental physical principles behind these relationships is crucial for creating bioinspired materials and structures with advanced functionalities. The eggshell is a remarkable example with a well-designed structure to balance the trade-off as it provides mechanical protection while still being easy for hatching. In this study, we investigate the underlying mechanical design principles of chicken eggshells under various loading conditions through a combination of experiments and simulations. The unique geometry and structure of the eggshell play a critical role in achieving an excellent balance between mechanical toughness and ease of hatching. The effects of eggshell membranes are elucidated to tune the mechanical properties of the eggshell to further enhance this balance. Moreover, a mechanics-based three-index model is proposed based on these design principles, suggesting the optimal eggshell thickness design to improve survivability across a broad range of avian species with varying egg sizes. The survivability-design relationships hold great potential for the development of improved structural materials for applications in sports safety equipment and the packaging industry. STATEMENT OF SIGNIFICANCE: The fundamental physical principles underlying the complex structure-property relationships in biological materials are uncovered in this study, with a particular focus on chicken eggshells as a prime example. Through the investigation of their mechanical design, we reveal the critical role of eggshell geometry and structure in achieving a balance between toughness and ease of hatching. Specifically, the crack resting effect is observed, making the eggshell easier to break from the inside than from the outside. Additionally, we explore the influence of eggshell membranes on this balance, contributing to the enhancement of the eggshell's mechanical properties. For the first time, we propose a three-index model that uncovers the underlying principles governing the evolution of eggshell thickness. This model suggests optimal thickness designs for diverse avian species, with the goal of enhancing egg survivability. These findings can guide the development of improved structural materials with advanced functionalities, enabling greater safety and efficiency in a wide range of applications.

Keratan sulfate, an electrosensory neurosentient bioresponsive cell instructive glycosaminoglycan

The roles of keratan sulfate (KS) as a proton detection glycosaminoglycan in neurosensory processes in the central and peripheral nervous systems is reviewed. The functional properties of the KS-proteoglycans aggrecan, phosphacan, podocalyxcin as components of perineuronal nets in neurosensory processes in neuronal plasticity, cognitive learning and memory are also discussed. KS-glycoconjugate neurosensory gels used in electrolocation in elasmobranch fish species and KS substituted mucin like conjugates in some tissue contexts in mammals need to be considered in sensory signalling. Parallels are drawn between KS's roles in elasmobranch fish neurosensory processes and its roles in mammalian electro mechanical transduction of acoustic liquid displacement signals in the cochlea by the tectorial membrane and stereocilia of sensory inner and outer hair cells into neural signals for sound interpretation. The sophisticated structural and functional proteins which maintain the unique high precision physical properties of stereocilia in the detection, transmittance and interpretation of acoustic signals in the hearing process are important. The maintenance of the material properties of stereocilia are essential in sound transmission processes. Specific, emerging roles for low sulfation KS in sensory bioregulation are contrasted with the properties of high charge density KS isoforms. Some speculations are made on how the molecular and electrical properties of KS may be of potential application in futuristic nanoelectronic, memristor technology in advanced ultrafast computing devices with low energy requirements in nanomachines, nanobots or molecular switches which could be potentially useful in artificial synapse development. Application of KS in such innovative areas in bioregulation are eagerly awaited.

Weighted single-step GWAS identified candidate genes associated with carcass traits in a Chinese yellow-feathered chicken population

Carcass traits in broiler chickens are complex traits that are influenced by multiple genes. To gain deeper insights into the genetic mechanisms underlying carcass traits, here we conducted a weighted single-step genome-wide association study (wssGWAS) in a population of Chinese yellow-feathered chicken. The objective was to identify genomic regions and candidate genes associated with carcass weight (CW), eviscerated weight with giblets (EWG), eviscerated weight (EW), breast muscle weight (BMW), drumstick weight (DW), abdominal fat weight (AFW), abdominal fat percentage (AFP), gizzard weight (GW), and intestine length (IL). A total of 1,338 broiler chickens with phenotypic and pedigree information were included in this study. Of these, 435 chickens were genotyped using a 600K single nucleotide polymorphism chip for association analysis. The results indicate that the most significant regions for 9 traits explained 2.38% to 5.09% of the phenotypic variation, from which the region of 194.53 to 194.63Mb on chromosome 1 with the gene RELT and FAM168A identified on it was significantly associated with CW, EWG, EW, BMW, and DW. Meanwhile, the 5 traits have a strong genetic correlation, indicating that the region and the genes can be used for further research. In addition, some candidate genes associated with skeletal muscle development, fat deposition regulation, intestinal repair, and protection were identified. Gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses suggested that the genes are involved in processes such as vascular development (CD34, FGF7, FGFR3, ITGB1BP1, SEMA5A, LOXL2), bone formation (FGFR3, MATN1, MEF2D, DHRS3, SKI, STC1, HOXB1, HOXB3, TIPARP), and anatomical size regulation (ADD2, AKT1, CFTR, EDN3, FLII, HCLS1, ITGB1BP1, SEMA5A, SHC1, ULK1, DSTN, GSK3B, BORCS8, GRIP2). In conclusion, the integration of phenotype, genotype, and pedigree information without creating pseudo-phenotype will facilitate the genetic improvement of carcass traits in chickens, providing valuable insights into the genetic architecture and potential candidate genes underlying carcass traits, enriching our understanding and contributing to the breeding of high-quality broiler chickens.

Genome-Wide Analysis of lncRNA and mRNA Expression in the Uterus of Laying Hens during Aging

Eggshell plays an essential role in preventing physical damage and microbial invasions. Therefore, the analysis of genetic regulatory mechanisms of eggshell quality deterioration during aging in laying hens is important for the biosecurity and economic performance of poultry egg production worldwide. This study aimed to compare the differences in the expression profiles of long non-coding RNAs (lncRNAs) and mRNAs between old and young laying hens by the method of high-throughput RNA sequencing to identify candidate genes associated with aging in the uterus of laying hens. Overall, we detected 176 and 383 differentially expressed (DE) lncRNAs and mRNAs, respectively. Moreover, functional annotation analysis based on the Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases revealed that DE-lncRNAs and DE-mRNAs were significantly enriched in “phosphate-containing compound metabolic process”, “mitochondrial proton-transporting ATP synthase complex”, “inorganic anion transport”, and other terms related to eggshell calcification and cuticularization. Through integrated analysis, we found that some important genes such as FGF14, COL25A1, GPX8, and GRXCR1 and their corresponding lncRNAs were expressed differentially between two groups, and the results of quantitative real-time polymerase chain reaction (qPCR) among these genes were also in excellent agreement with the sequencing data. In addition, our study found that TCONS_00181492, TCONS_03234147, and TCONS_03123639 in the uterus of laying hens caused deterioration of eggshell quality in the late laying period by up-regulating their corresponding target genes FGF14, COL25A1, and GRXCR1 as well as down-regulating the target gene GPX8 by TCONS_01464392. Our findings will provide a valuable reference for the development of breeding programs aimed at breeding excellent poultry with high eggshell quality or regulating dietary nutrient levels to improve eggshell quality.

High value applications and current commercial market for eggshell membranes and derived bioactives

Chicken eggshell membrane (ESM) is a highly insoluble structure that is greatly stabilized by extensive desmosine, isodesmosine, and disulfide cross-linkages. The ESM possesses numerous biological functions including anti-microbial, anti-inflammatory, anti-wrinkle, and antioxidant activities. The ESM is mainly proteinaceous; proteomics and bioinformatics analysis of ESM has identified > 500 proteins, such as collagens, glycoproteins, avian beta-defensins, and lysozyme. ESM also contains significant amounts of carbohydrate, including hyaluronic acid (HA). In general, HA plays an important role in tissue hydration and cellular mechanisms such as growth, differentiation, and transport, and has diverse health and medical applications. Despite ESM being rich in important bioactive compounds, it is often considered as a waste product of the egg-breaking industry and is under-utilized. A major challenge for the successful commercial exploitation of ESM and bioactive constituents is its limited solubility and bioavailability due to cross-linkages of ESM fibers. Various processing and extraction methods are employed to overcome these limitations and improve the production of HA and collagen-based ESM formats. Moreover, we believe that there is a wide scope to exploit ESM for novel applications, leading to new intellectual property (IP) and patenting opportunities. This review presents an overview of scientific background, IP landscape and current commercial market for ESM and derived bioactives including collagens and HA. A detailed literature survey is provided for each area of interest. We analyze regulatory guidelines for ESM, contrasting quality control / microbial safety assessment in cosmetics and personal care products (hazard based) with that of the food industry (risk-based). New perspectives for upcycling of ESM waste to commercially viable high-value biomaterials as nutraceutical supplements and as cosmetics ingredients are discussed. This overview of ESM separation techniques and applications could form the basis for directed research and product development in order to exploit the unique bioactivities of ESM.

Proteomic Analysis of Chicken Chorioallantoic Membrane (CAM) during Embryonic Development Provides Functional Insight

In oviparous animals, the egg contains all resources required for embryonic development. The chorioallantoic membrane (CAM) is a placenta-like structure produced by the embryo for acid-base balance, respiration, and calcium solubilization from the eggshell for bone mineralization. The CAM is a valuable in vivo model in cancer research for development of drug delivery systems and has been used to study tissue grafts, tumor metastasis, toxicology, angiogenesis, and assessment of bacterial invasion. However, the protein constituents involved in different CAM functions are poorly understood. Therefore, we have characterized the CAM proteome at two stages of development (ED12 and ED19) and assessed the contribution of the embryonic blood serum (EBS) proteome to identify CAM-unique proteins. LC/MS/MS-based proteomics allowed the identification of 1470, 1445, and 791 proteins in CAM (ED12), CAM (ED19), and EBS, respectively. In total, 1796 unique proteins were identified. Of these, 175 (ED12), 177 (ED19), and 105 (EBS) were specific to these stages/compartments. This study attributed specific CAM protein constituents to functions such as calcium ion transport, gas exchange, vasculature development, and chemical protection against invading pathogens. Defining the complex nature of the CAM proteome provides a crucial basis to expand its biomedical applications for pharmaceutical and cancer research.

Polymorphism analysis and expression profile of the estrogen receptor 2 gene in Leizhou black duck

Our previous study on the ovarian transcriptomic analysis in Leizhou black duck revealed that the ESR2 gene was involved in hormone regulation in reproduction and the estrogen signaling pathway related to reproductive performance was enriched. This suggested that ESR2 may have a functional role in the reproductive performance of the Leizhou black duck. Thus, this study aimed at evaluating the polymorphism of the ESR2 gene and its association with egg-laying traits and the distribution pattern of ESR2 mRNA in laying and non-laying Leizhou black ducks. In this study, genomic DNA was extracted from blood samples of 101 Leizhou black ducks to identify single nucleotide polymorphisms (SNPs) of the ESR2 gene to elucidate molecular markers highly associated with egg-laying traits. Four each of laying and non-laying Leizhou black ducks were selected to collect different tissues to analyze the ESR2 gene expression. A total of 23 SNPs were identified and association analysis of the single SNP sites showed that SNPs g.56805646 T>C and exon 3-20G>A were significantly (P < 0.05) associated with egg weight. Ducks with CT and AG genotypes had significantly higher (P < 0.05) egg weights than their respective other genotypes. Haplotype association analysis of g.56805646 T>C and exon 3-20G>A showed that the haplotypes were significantly associated with egg weight. Higher egg weight was seen in individuals with H3H4 haplotypes. In the hypothalamus-pituitary-gonadal (HPG) axis, the results of qRT/PCR showed that ESR2 mRNA was significantly (P < 0.05) expressed in the ovaries of both duck groups than in the hypothalamus and pituitary. In the oviduct, ESR2 was significantly (P < 0.05) higher in the infundibulum and magnum of laying and non-laying ducks respectively. This study provides a molecular marker for selecting Leizhou black ducks for egg production. In addition, it offers theoretical knowledge for studying the related biological functions of the ESR2 gene at the cellular level.

Cuticle deposition duration in the uterus is correlated with eggshell cuticle quality in White Leghorn laying hens

The cuticle formed in the uterus is the outermost layer as the first defense line of eggshell against microbial invasions in most avian species, and analyzing its genetic regulation and influencing factors are of great importance to egg biosecurity in poultry production worldwide. The current study compared the uterine transcriptome and proteome of laying hens producing eggs with good and poor cuticle quality (GC and PC, the top and tail of the cuticle quality distribution), and identified several genes involved with eggshell cuticle quality (ESCQ). Overall, transcriptomic analysis identified 53 differentially expressed genes (DEGs) between PC versus GC group hens, among which 25 were up-regulated and 28 were down-regulated. No differences were found in the uterine proteome. Several DEGs, including PTGDS, PLCG2, ADM and PRLR related to uterine functions and reproductive hormones, were validated by qPCR analysis. Egg quality measurements between GC and PC hens showed GC hens had longer laying interval between two consecutive ovipositions (25.64 ± 1.23 vs 24.94 ± 1.12 h) and thicker eggshell thickness (352.01 ± 23.04 vs 316.20 ± 30.58 μm) (P < 0.05). Apart from eggshell traits, other egg quality traits didn't differ. The result demonstrated eggshell and cuticle deposition duration in the uterus is one of the major factors affecting ESCQ in laying hens. PTGDS, PLCG2, ADM and PRLR genes were discovered and might play crucial roles in cuticle deposition by regulating the uterine muscular activities and secretion function. The findings in the present study provide new insights into the genetic regulation of cuticle deposition in laying hens and establish a foundation for further investigations.

How to build a puncture- and breakage-resistant eggshell? Mechanical and structural analyses of avian brood parasites and their hosts

Evolved eggshell strength is greater in several lineages of obligate avian brood parasites (birds that lay their eggs in other species' nests) than in their hosts. Greater strength is typically indirectly implied by eggshell thickness comparisons between parasites and hosts. Nevertheless, there is strong evidence that the eggshell structural organization differentially influences its mechanical properties. Using instrumental puncture tests and SEM/EBSD and XRD techniques, we studied the most relevant eggshell mechanical, textural, ultrastructural and microstructural features between several host species and their parasitic cowbirds (Molothrus spp.). These parasitic species display different egg-destructive behaviors, reducing host reproductive fitness, including the more frequently host-egg puncturing M. rufoaxillaris and M. bonariensis, and the host egg-removing M. ater. The results, analyzed using a phylogenetic comparative approach, showed interspecific patterns in the mechanical and structural features. Overall, the eggshells of the two egg-puncturing parasites (but not of M. ater) were stronger, stiffer and required greater stress to produce a fracture than the respective hosts' eggs. These features were affected by eggshell microstructure and ultrastructure, related to the increase in the intercrystalline boundary network acting in cooperation with the increase in palisade layer thickness. Both structural features generate more options and greater lengths of intercrystalline paths, increasing the energy consumed in crack or fissure propagation. The reported patterns of all these diverse eggshell features support a new set of interpretations, confirming several hypotheses regarding the impact of the two reproductive strategies (parasitic versus parental) and parasitic egg destruction behaviors (more versus less frequently puncturing).

Current Insights on the Diverse Structures and Functions in Bacterial Collagen-like Proteins

The dearth of knowledge on the diverse structures and functions in bacterial collagen-like proteins is in stark contrast to the deep grasp of structures and functions in mammalian collagen, the ubiquitous triple-helical scleroprotein that plays a central role in tissue architecture, extracellular matrix organization, and signal transduction. To fill and highlight existing gaps due to the general paucity of data on bacterial CLPs, we comprehensively reviewed the latest insight into their functional and structural diversity from multiple perspectives of biology, computational simulations, and materials engineering. The origins and discovery of bacterial CLPs were explored. Their genetic distribution and molecular architecture were analyzed, and their structural and functional diversity in various bacterial genera was examined. The principal roles of computational techniques in understanding bacterial CLPs' structural stability, mechanical properties, and biological functions were also considered. This review serves to drive further interest and development of bacterial CLPs, not only for addressing fundamental biological problems in collagen but also for engineering novel biomaterials. Hence, both biology and materials communities will greatly benefit from intensified research into the diverse structures and functions in bacterial collagen-like proteins.

Albumen Quality of Fresh and Stored Table Eggs: Hen Genotype as a Further Chance for Consumer Choice

Simple Summary

Consumer interest in food products and their origins is increasing. Knowledge of egg production and quality of purebred hens during the productive period is required for a niche market sustaining and encouraging biodiversity and the peculiarities of the products that consumers can appreciate. Egg production and quality of the eggshell and albumen in fresh and stored eggs of two Italian dual-purpose purebreds (Ermellinata di Rovigo (ER); Robusta maculata (RM)) and two hybrid genotypes (Hy-Line Brown (HB); Hy-Line White (HW)) reared outdoors were compared throughout the laying period. RM breed (brown eggshell) showed fresh and stored eggs with a good eggshell thickness, and Haugh Units (HU) quite stable along the production period; RM total egg mass was lower than ER (light brown eggshell) which showed fresh and stored eggs with more variable HU, due also to a possible effect of lower eggshell thickness and pigmentation, and shape index. The hybrids produced a higher total egg mass than the purebreds and showed an intermediate variation of the egg quality, with HU higher than those of ER and RM only in 1 d eggs, but not in stored eggs.

Abstract

The quality of fresh (1 d) and stored (7–14–21 d, 21 °C) eggs was studied in Italian dual-purpose breeds (Ermellinata di Rovigo (ER), Robusta maculata (RM)) and hybrids (Hy-Line Brown (HB), Hy-Line White36 (HW)), reared outdoors (4 m²/bird) and fed commercial feed. The eggs were analyzed at 4 ages, throughout different seasonal environmental conditions, from summer (31, 35 weeks; 25 °C) until autumn (39, 43 weeks, 15 °C). Each genotype showed significant (p < 0.01) changes in egg quality. In 1 d eggs, the eggshell thickness changed in RM and HW (quadratic), decreased linearly in ER; Haugh Units (HU) changed (ER–cubic) and decreased (hybrids-linear). In 7 d and 14 d eggs, HU linearly (p < 0.01) decreased, except in RM. In 21 d eggs, HU (ER linear decrease; HB, HW quadratic) changed. Significant negative correlations between albumen pH and height were seen in ER (at 1 d, 14 d, 21 d) and HW (at each storage time) eggs, and in RM and HB only in 1 d eggs. RM showed a quite stable albumen quality and a lower total egg mass than ER which showed a more variable albumen quality, due also to a lower eggshell thickness and shape index. The hybrids produced a higher total egg mass than the purebreds and showed an intermediate variation of the egg quality, with an albumen quality higher than those of ER and RM only in 1 d egg, as a result of a higher albumen weight.

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.

Quantitative Comparative Proteomic Analysis of Chicken Egg Vitelline Membrane Proteins during High-Temperature Storage

To explore the thermally induced alterations in chicken egg vitelline membrane (CEVM) protein abundances, a comparative proteomic analysis of CEVM after 10 days of storage at 30 °C was performed. Altogether, 981 proteins were identified, of which 124 protein abundances were decreased and 79 were increased. Bioinformatic analysis suggested that the altered proteins were related to structure (n = 10), mechanical properties (n = 13), chaperone (n = 15), antibacterial (n = 12), and antioxidant (n = 3). Alterations in abundances of structural proteins, possibly resulting from the disintegration of these complexes, were observed in this study, suggesting a loss in fibrous structure. Several proteins involved in mechanical strength (n = 10), elasticity (n = 3), and chaperone were decreased in abundances, which indicated that deficits in these proteins might affect the CEVM mechanical properties. These findings will extend our understanding of CEVM deterioration during high-temperature storage from a proteomic perspective.

Label-free proteomic analysis reveals the differentiation between unfertilized and fertilized Beijing-You chicken eggs

Egg fertilization is a dynamic process, including varieties of biochemical changes. To better understand the molecular mechanisms during the egg embryo development, the objective of this study was to quantify protein expression changes between fertilized and unfertilized Beijing-You chicken eggs using label-free liquid chromatography-tandem mass spectrometry method. The results showed that a total of 1241 proteins were identified from fertilized and unfertilized eggs, 229 proteins were observed difference in fertilized eggs (p < 0.05) compared with that in unfertilized eggs. The expressions of 86 proteins were up-regulated and 48 proteins were down-regulated in fertilized eggs. STRING database analysis and Gene Ontology analysis results showed that these differentially expressed proteins significantly interacted and were involved in lipid transport and inflammatory response biological processes. The mRNA and protein expression levels of most differentially expressed proteins Apolipoprotein B, Fibrinogen alpha chain, Transferrin receptor protein 1, Phospholipid transfer protein and Vimentin were validated by RT-PCR and western blot. These results could provide possible novel insights for the molecular mechanism of egg fertilization.

Identification of Age-Specific and Common Key Regulatory Mechanisms Governing Eggshell Strength in Chicken Using Random Forests

In today's chicken egg industry, maintaining the strength of eggshells in longer laying cycles is pivotal for improving the persistency of egg laying. Eggshell development and mineralization underlie a complex regulatory interplay of various proteins and signaling cascades involving multiple organ systems. Understanding the regulatory mechanisms influencing this dynamic trait over time is imperative, yet scarce. To investigate the temporal changes in the signaling cascades, we considered eggshell strength at two different time points during the egg production cycle and studied the genotype-phenotype associations by employing the Random Forests algorithm on chicken genotypic data. For the analysis of corresponding genes, we adopted a well established systems biology approach to delineate gene regulatory pathways and master regulators underlying this important trait. Our results indicate that, while some of the master regulators (Slc22a1 and Sox11) and pathways are common at different laying stages of chicken, others (e.g., Scn11a, St8sia2, or the TGF- β pathway) represent age-specific functions. Overall, our results provide: (i) significant insights into age-specific and common molecular mechanisms underlying the regulation of eggshell strength; and (ii) new breeding targets to improve the eggshell quality during the later stages of the chicken production cycle.

Signatures of Divergence, Invasiveness, and Terrestrialization Revealed by Four Apple Snail Genomes

The family Ampullariidae includes both aquatic and amphibious apple snails. They are an emerging model for evolutionary studies due to the high diversity, ancient history, and wide geographical distribution. Insight into drivers of ampullariid evolution is hampered, however, by the lack of genomic resources. Here, we report the genomes of four ampullariids spanning the Old World (Lanistes nyassanus) and New World (Pomacea canaliculata, P. maculata, and Marisa cornuarietis) clades. The ampullariid genomes have conserved ancient bilaterial karyotype features and a novel Hox gene cluster rearrangement, making them valuable in comparative genomic studies. They have expanded gene families related to environmental sensing and cellulose digestion, which may have facilitated some ampullarids to become notorious invasive pests. In the amphibious Pomacea, novel acquisition of an egg neurotoxin and a protein for making the calcareous eggshell may have been key adaptations enabling their transition from underwater to terrestrial egg deposition.

Keratan sulfate (KS)-proteoglycans and neuronal regulation in health and disease: the importance of KS-glycodynamics and interactive capability with neuroregulatory ligands

Compared to the other classes of glycosaminoglycans (GAGs), that is, chondroitin/dermatan sulfate, heparin/heparan sulfate and hyaluronan, keratan sulfate (KS), have the least known of its interactive properties. In the human body, the cornea and the brain are the two most abundant tissue sources of KS. Embryonic KS is synthesized as a linear poly-N-acetyllactosamine chain of d-galactose-GlcNAc repeat disaccharides which become progressively sulfated with development, sulfation of GlcNAc is more predominant than galactose. KS contains multi-sulfated high-charge density, monosulfated and non-sulfated poly-N-acetyllactosamine regions and thus is a heterogeneous molecule in terms of chain length and charge distribution. A recent proteomics study on corneal KS demonstrated its interactivity with members of the Slit-Robbo and Ephrin-Ephrin receptor families and proteins which regulate Rho GTPase signaling and actin polymerization/depolymerization in neural development and differentiation. KS decorates a number of peripheral nervous system/CNS proteoglycan (PG) core proteins. The astrocyte KS-PG abakan defines functional margins of the brain and is up-regulated following trauma. The chondroitin sulfate/KS PG aggrecan forms perineuronal nets which are dynamic neuroprotective structures with anti-oxidant properties and roles in neural differentiation, development and synaptic plasticity. Brain phosphacan a chondroitin sulfate, KS, HNK-1 PG have roles in neural development and repair. The intracellular microtubule and synaptic vesicle KS-PGs MAP1B and SV2 have roles in metabolite transport, storage, and export of neurotransmitters and cytoskeletal assembly. MAP1B has binding sites for tubulin and actin through which it promotes cytoskeletal development in growth cones and is highly expressed during neurite extension. The interactive capability of KS with neuroregulatory ligands indicate varied roles for KS-PGs in development and regenerative neural processes.

Biomineralization in modern avian calcified eggshells: similarity versus diversity

Avian eggshells are composed of several layers made of organic compounds and a mineral phase (calcite), and the general structure is basically the same in all species. A comparison of the structure, crystallography, and chemical composition shows that despite an overall similarity, each species has its own structure, crystallinity, and composition. Eggshells are a perfect example of the crystallographic versus biological concept of the formation and growth mechanisms of calcareous biominerals: the spherulitic-columnar structure is described as "a typical case of competitive crystal growth", but it is also said that the eggshell matrix components regulate eggshell mineralization. Electron back scattered diffraction (EBSD) analyses show that the crystallinity differs between different species. Nevertheless, the three layers are composed of rounded granules, and neither facets nor angles are visible. In-situ analyses show the heterogeneous distribution of chemical elements throughout the thickness of single eggshell. The presence of organic matrices other than the outer and inner membranes in eggshells is confirmed by thermograms and infrared spectrometry, and the differences in quality and quantity depend on the species. Thus, as in other biocrystals, crystal growth competition is not enough to explain these differences, and there is a strong biological control of the eggshell secretion.

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.

Domestic Fowl Breed Variation in Egg White Protein Expression: Application of Proteomics and Transcriptomics

Avian egg white is essential for protecting and nourishing bird embryos during their development. Being produced in the female magnum, variability in hen oviduct gene expression may affect egg white composition in domestic chickens. Since traditional poultry breeds may represent a source of variation, in the present study we describe the egg white proteome (mass spectrometry) and corresponding magnum transcriptome (high-throughput sequencing) for 20 hens from five domestic fowl breeds (large breeds: Araucana, Czech golden pencilled, Minorca; and small breeds: Booted bantam, Rosecomb bantam). In total, we identified 189 egg white proteins and 16391 magnum-expressed genes. The majority of egg white protein content comprised proteins with an antimicrobial function. Despite general similarity, Between-class Principal Component Analysis revealed significant breed-specific variability in protein abundances, differentiating especially small and large breeds. Though we found strong association between magnum mRNA expression and egg white protein abundance across genes, coinertia analysis revealed no transcriptome/proteome costructure at the individual level. Our study is the first to show variation in protein abundances in egg white across chicken breeds with potential effects on egg quality, biosafety, and chick development. The observed interindividual variation probably results from post-transcriptional regulation creating a discrepancy between proteomic and transcriptomic data.

Ange K, Han X, Edsinger E, Sohn J, Linhardt RJ. Structural and Functional Components of the Skate Sensory Organ Ampullae of Lorenzini

The skate, a cartilaginous fish related to sharks and rays, possesses a unique electrosensitive sensory organ known as the ampullae of Lorenzini (AoL). This organ is responsible for the detection of weak electric field changes caused by the muscle contractions of their prey. While keratan sulfate (KS) is believed to be a component of a jelly that fills this sensory organ and has been credited with its high proton conductivity, modern analytical methods have not been applied to its characterization. Surprisingly, total glycosaminoglycan (GAG) analysis demonstrates that the KS from skate jelly is extraordinarily pure, containing no other GAGs. This KS had a molecular weight of 20 to 30 kDa, consisting primarily of N-linked KS comprised mostly of a monosulfated disaccharide repeating unit, →3) Gal (1→4) GlcNAc6S (1→. Proteomic analysis of AoL jelly suggests that transferrin, keratin, and mucin serve as KS core proteins. Actin and tropomyosin are responsible for assembling the macrostructure of the jelly, and parvalbumin α-like protein and calreticulin regulate calcium and potassium channels involved in the transduction of the electrical signal, once conducted down the AoL by the jelly, serving as the molecular basis for electroreception.

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.

Membrane-containing virus particles exhibit the mechanics of a composite material for genome protection

The protection of the viral genome during extracellular transport is an absolute requirement for virus survival and replication. In addition to the almost universal proteinaceous capsids, certain viruses add a membrane layer that encloses their double-stranded (ds) DNA genome within the protein shell. Using the membrane-containing enterobacterial virus PRD1 as a prototype, and a combination of nanoindentation assays by atomic force microscopy and finite element modelling, we show that PRD1 provides a greater stability against mechanical stress than that achieved by the majority of dsDNA icosahedral viruses that lack a membrane. We propose that the combination of a stiff and brittle proteinaceous shell coupled with a soft and compliant membrane vesicle yields a tough composite nanomaterial well-suited to protect the viral DNA during extracellular transport.

Keratan sulfate, a complex glycosaminoglycan with unique functional capability

From an evolutionary perspective keratan sulfate (KS) is the newest glycosaminoglycan (GAG) but the least understood. KS is a sophisticated molecule with a diverse structure, and unique functional roles continue to be uncovered for this GAG. The cornea is the richest tissue source of KS in the human body but the central and peripheral nervous systems also contain significant levels of KS and a diverse range of KS-proteoglycans with essential functional roles. KS also displays important cell regulatory properties in epithelial and mesenchymal tissues and in bone and in tumor development of diagnostic and prognostic utility. Corneal KS-I displays variable degrees of sulfation along the KS chain ranging from non-sulfated polylactosamine, mono-sulfated and disulfated disaccharide regions. Skeletal KS-II is almost completely sulfated consisting of disulfated disaccharides interrupted by occasional mono-sulfated N-acetyllactosamine residues. KS-III also contains highly sulfated KS disaccharides but differs from KS-I and KS-II through 2-O-mannose linkage to serine or threonine core protein residues on proteoglycans such as phosphacan and abakan in brain tissue. Historically, the major emphasis on the biology of KS has focused on its sulfated regions for good reason. The sulfation motifs on KS convey important molecular recognition information and direct cell behavior through a number of interactive proteins. Emerging evidence also suggest functional roles for the poly-N-acetyllactosamine regions of KS requiring further investigation. Thus further research is warranted to better understand the complexities of KS.

Transcriptional profiling of liver in riboflavin-deficient chicken embryos explains impaired lipid utilization, energy depletion, massive hemorrhaging, and delayed feathering

BACKGROUND

A strain of Leghorn chickens (rd/rd), unable to produce a functional riboflavin-binding protein, lays riboflavin-deficient eggs, in which all embryos suddenly die at mid-incubation (days 13-15). This malady, caused by riboflavin deficiency, leads to excessive lipid accumulation in liver, impaired β-oxidation of lipid, and severe hypoglycemia prior to death. We have used high-density chicken microarrays for time-course transcriptional scans of liver in chicken embryos between days 9-15 during this riboflavin-deficiency-induced metabolic catastrophe. For comparison, half of rd/rd embryos (n = 16) were rescued from this calamity by injection of riboflavin just prior to incubation of fertile eggs from rd/rd hens.

RESULTS

No significant differences were found between hepatic transcriptomes of riboflavin-deficient and riboflavin-rescued embryos at the first two ages (days 9 and 11). Overall, we found a 3.2-fold increase in the number of differentially expressed hepatic genes between day 13 (231 genes) and day 15 (734 genes). Higher expression of genes encoding the chicken flavoproteome was more evident in rescued- (15 genes) than in deficient-embryos (4 genes) at day 15. Diminished activity of flavin-dependent enzymes in riboflavin-deficient embryos blocks catabolism of yolk lipids, which normally serves as the predominant source of energy required for embryonic development.

CONCLUSIONS

Riboflavin deficiency in mid-stage embryos leads to reduced expression of numerous genes controlling critical functions, including β-oxidation of lipids, blood coagulation and feathering. Surprisingly, reduced expression of feather keratin 1 was found in liver of riboflavin-deficient embryos at e15, which could be related to their delayed feathering and sparse clubbed down. A large number of genes are expressed at higher levels in liver of riboflavin-deficient embryos; these up-regulated genes control lipid storage/transport, gluconeogenesis, ketogenesis, protein catabolism/ubiquitination and cell death.

Chemistry and Enzymology of Disulfide Cross-Linking in Proteins

Cysteine thiols are among the most reactive functional groups in proteins, and their pairing in disulfide linkages is a common post-translational modification in proteins entering the secretory pathway. This modest amino acid alteration, the mere removal of a pair of hydrogen atoms from juxtaposed cysteine residues, contrasts with the substantial changes that characterize most other post-translational reactions. However, the wide variety of proteins that contain disulfides, the profound impact of cross-linking on the behavior of the protein polymer, the numerous and diverse players in intracellular pathways for disulfide formation, and the distinct biological settings in which disulfide bond formation can take place belie the simplicity of the process. Here we lay the groundwork for appreciating the mechanisms and consequences of disulfide bond formation in vivo by reviewing chemical principles underlying cysteine pairing and oxidation. We then show how enzymes tune redox-active cofactors and recruit oxidants to improve the specificity and efficiency of disulfide formation. Finally, we discuss disulfide bond formation in a cellular context and identify important principles that contribute to productive thiol oxidation in complex, crowded, dynamic environments.

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.

Female Reproductive System and Immunology

Health of the reproductive organs is essential for formation and production of high quality and hygienic eggs. It is of importance to review the structures and functions of female reproductive system for better understanding of the mechanism by which the eggs are formed. The unique functions of ovarian cells for follicular growth and differentiation as well as steroidogenesis and oocyte maturation are regulated by gonadotropins and gonadal steroids. The oviduct is responsible for egg formation, while the unique function to store sperms for a prolonged period takes place in the specific tissue of this organ. The unique innate and adaptive immuno-defense systems that play essential role to prevent infection are developed in the ovary and oviduct. Toll-like receptors (TLRs) that recognize the molecular pattern of microbes and initiate the immunoresponse are expressed in those organs. Avian β-defensins (AvBDs), a member of antimicrobial peptides, are synthesized by the ovarian and oviductal cells. Challenge of those cells by TLR ligands upregulates the expression of proinflammatory cytokines, which in turn stimulate the expression of AvBDs. The adaptive immune system in the ovary and oviduct is also unique, since the migration of lymphocytes is enhanced by estrogens. In contrast to the development of immuno-defense system, spontaneous ovarian cancer and uterine fibroids appear more frequently in chickens than in mammals, and thus chickens could be used as a model for studying these diseases. Thus the avian reproductive organs have unique functions not only for egg formation but also for the immuno-defense system, which is essential for prevention of infection and production of hygienic eggs.

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.

Lysyl Oxidase Isoforms and Potential Therapeutic Opportunities for Fibrosis and Cancer

INTRODUCTION

The lysyl oxidase family of enzymes is classically known as being required for connective tissue maturation by oxidizing lysine residues in elastin and lysine and hydroxylysine residues in collagen precursors. The resulting aldehydes then participate in cross-link formation, which is required for normal connective tissue integrity. These enzymes have biological functions that extend beyond this fundamental biosynthetic role, with contributions to angiogenesis, cell proliferation, and cell differentiation. Dysregulation of lysyl oxidases occurs in multiple pathologies including fibrosis, primary and metastatic cancers, and complications of diabetes in a variety of tissues.

AREAS COVERED

This review summarizes the major findings of novel roles for lysyl oxidases in pathologies, and highlights some of the potential therapeutic approaches that are in development and which stem from these new findings.

EXPERT OPINION

Fundamental questions remain regarding the mechanisms of novel biological functions of this family of proteins, and regarding functions that are independent of their catalytic enzyme activity. However, progress is underway in the development of isoform-specific pharmacologic inhibitors, potential therapeutic antibodies and gaining an increased understanding of both tumor suppressor and metastasis promotion activities. Ultimately, this is likely to lead to novel therapeutic agents.