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

Implications of intracrystalline OC17 on the protection of lattice incorporated proteins

Biogenic CaCO3 formation is regulated by crystallization proteins during crystal growth. Interactions of proteins with nascent mineral surfaces trigger proteins to be incorporated into the crystal lattice. As a result of incorporation, these intracrystalline proteins are protected in the lattice, an example of which is ancient eggshell proteins that have persisted in CaCO3 for thousands of years even under harsh environmental conditions. OC17 is an eggshell protein known to interact with CaCO3 during eggshell formation during which OC17 becomes incorporated into the lattice. Understanding protein incorporation into CaCO3 could offer insights into protein stability inside crystals. Here, we study the protection of OC17 in the CaCO3 lattice. Using thermogravimetric analysis we show that the effect of temperature on intracrystalline proteins of eggshells is negligible below 250 °C. Next, we show that lattice incorporation protects the OC17 structure despite a heat-treatment step that is shown to denature the protein. Because incorporated proteins need to be released from crystals, we verify metal chelation as a safe crystal dissolution method to avoid protein denaturation during reconstitution. Finally, we optimize the recombinant expression of OC17 which could allow engineering OC17 for engineered intracrystalline entrapment studies.

Utilization of Eggshell Waste Calcite as a Sorbent for Rare Earth Element Recovery

The green energy transition requires rare earth elements (REE) for the permanent magnets used in electric cars and wind turbines. REE extraction and beneficiation are chemically intensive and highly damaging to the environment. We investigated the use of eggshell waste as a sustainable alternative sorbent for the capture and separation of REE from aqueous solutions. Hen eggshell calcite was placed in multi-REE (La, Nd, Dy) solutions at 25 to 205 °C for up to 3 months. A pervasive diffusion of the REE inside the eggshell calcite was observed along pathways formed by the intracrystalline organic matrix and calcite crystal boundaries. At 90 °C, kozoite (REECO3OH, orthorhombic) spherulites precipitate on the surface of the dissolving calcite. At 165 and 205 °C, an interface-coupled dissolution-precipitation mechanism is observed, resulting in the complete dissolution of the calcite shell and its pseudomorphic replacement by polycrystalline kozoite. At 205 °C, kozoite is slowly replaced by hydroxylbastnäsite (REECO3OH, hexagonal), the stable form of the rare earth hydroxycarbonate polymorphs. Our results demonstrate two potential applications of eggshell waste for the uptake of rare earth elements in solution: at low temperatures, as a mixed organic-inorganic adsorbent and absorbent, given sufficient sorption time; and at higher temperatures, as an efficient sacrificial template for the precipitation of rare earth hydroxycarbonates.

Material-specific binding peptides empower sustainable innovations in plant health, biocatalysis, medicine and microplastic quantification

Material-binding peptides (MBPs) have emerged as a diverse and innovation-enabling class of peptides in applications such as plant-/human health, immobilization of catalysts, bioactive coatings, accelerated polymer degradation and analytics for micro-/nanoplastics quantification. Progress has been fuelled by recent advancements in protein engineering methodologies and advances in computational and analytical methodologies, which allow the design of, for instance, material-specific MBPs with fine-tuned binding strength for numerous demands in material science applications. A genetic or chemical conjugation of second (biological, chemical or physical property-changing) functionality to MBPs empowers the design of advanced (hybrid) materials, bioactive coatings and analytical tools. In this review, we provide a comprehensive overview comprising naturally occurring MBPs and their function in nature, binding properties of short man-made MBPs (<20 amino acids) mainly obtained from phage-display libraries, and medium-sized binding peptides (20-100 amino acids) that have been reported to bind to metals, polymers or other industrially produced materials. The goal of this review is to provide an in-depth understanding of molecular interactions between materials and material-specific binding peptides, and thereby empower the use of MBPs in material science applications. Protein engineering methodologies and selected examples to tailor MBPs toward applications in agriculture with a focus on plant health, biocatalysis, medicine and environmental monitoring serve as examples of the transformative power of MBPs for various industrial applications. An emphasis will be given to MBPs' role in detecting and quantifying microplastics in high throughput, distinguishing microplastics from other environmental particles, and thereby assisting to close an analytical gap in food safety and monitoring of environmental plastic pollution. In essence, this review aims to provide an overview among researchers from diverse disciplines in respect to material-(specific) binding of MBPs, protein engineering methodologies to tailor their properties to application demands, re-engineering for material science applications using MBPs, and thereby inspire researchers to employ MBPs in their research.

Comparative Analysis of the Ultrastructure, Bubble Pores, and Composition of Eggshells of Dwarf Layer-White and Guinea Fowl

The decrease in eggshell quality seriously affects production efficiency. Guinea fowl (GF) eggs possess strong eggshells because of their unique crystal structure, and few systematic studies have compared laying hen and GF eggs. Sixty eggs were collected from both 40-week-old Dwarf Layer-White (DWL-White) laying hens and GF, and the eggshell quality, ultrastructure, bubble pores, and composition were measured. The results showed that the DWL-White eggs had a higher egg weight and a lower eggshell strength, strength per unit weight, thickness, and ratio than the GF eggs (p < 0.01). There were differences in the mammillary layer thickness ratio, the effective layer thickness ratio, the quantity of bubble pores (QBPs), the ratio of the sum of the area of bubble pores to the area of the eggshell in each image (ARBE), and the average area of bubble pores (AABPs) between the DWL-White and GF eggs (p < 0.01). The composition analysis demonstrated that there were differences in the organic matter, inorganic matter, calcium, and phosphorus between the DWL-White and GF eggs (p < 0.01). There were positive associations between the mammillary knob number in the image and the QBPs and ARBE and a negative correlation with the AABPs in the DWL-White eggs (p < 0.01). This study observed distinctions that offer new insights into enhancing eggshell quality.

Enriching Eggs with Bioactive Compounds through the Inclusion of Grape Pomace in Laying Hens Diet: Effect on Internal and External Egg Quality Parameters

(1) Background: Grapes and their associated by-products (such as grape pomace, GP) stand out for their polyphenol content, which makes them a source of bioactive compounds with antioxidant capacity. The aim of this research was to determine if the inclusion of 50 g/kg of GP in the diet of hens could enrich eggs with antioxidants and to study its effect on internal and external egg quality parameters. (2) Methods: A trial was conducted with two genetic lines of hens, which were fed either a control diet or a diet containing 50 g/kg of GP. Performance, internal and external egg quality, and egg yolk content of vitamins E and A and gallic acid were determined. (3) Results: In eggs laid by hens fed a GP diet, Haugh units and yolk color scores were enhanced, and eggshells became thinner, but without affecting the breaking strength. No dietary effect was observed on the vitamin contents of the yolk. A higher gallic acid content was observed in the yolks of eggs laid by hens fed the GP diet, suggesting that some dietary phenolic compounds could be transferred to the eggs. Hen genetics influenced egg weight, albumen Haugh units, shell thickness, and α- and γ-tocopherol concentration in yolks. (4) Conclusions: Dietary inclusion of GP improved the internal quality of eggs, enriching yolks with a phenolic compound but reducing shell thickness.

Guinea fowl eggshell structural analysis at different scales reveals how organic matrix induces microstructural shifts that enhance its mechanical properties

Guinea fowl eggshells have an unusual structural arrangement that is different from that of most birds, consisting of two distinct layers with different microstructures. This bilayered organization, and distinct microstructural characteristics, provides it with exceptional mechanical properties. The inner layer, constituting about one third of the eggshell thickness, contains columnar calcite crystal units arranged vertically as in most bird shells. However, the thicker outer layer has a more complex microstructural arrangement formed by a switch to smaller calcite domains with diffuse/interlocking boundaries, partly resembling the interfaces seen in mollusk shell nacre. The switching process that leads to this remarkable second-layer microstructure is unknown. Our results indicate that the microstructural switching is triggered by changes in the inter- and intracrystalline organic matrix. During production of the outer microcrystalline layer in the later stages of eggshell formation, the interactions of organic matter with mineral induce an accumulation of defects that increase crystal mosaicity, instill anisotropic lattice distortions in the calcite structure, interrupt epitaxial growth, reduce crystallite size, and induce nucleation events which increase crystal misorientation. These structural changes, together with the transition between the layers and each layer having different microstructures, enhance the overall mechanical strength of the Guinea fowl eggshell. Additionally, our findings provide new insights into how biogenic calcite growth may be regulated to impart unique functional properties. STATEMENT OF SIGNIFICANCE: Avian eggshells are mineralized to protect the embryo and to provide calcium for embryonic chick skeletal development. Their thickness, structure and mechanical properties have evolved to resist external forces throughout brooding, yet ultimately allow them to crack open during chick hatching. One particular eggshell, that of the Guinea fowl, has structural features very different from other galliform birds - it is bilayered, with an inner columnar mineral structure (like in most birds), but it also has an outer layer with a complex microstructure which contributes to its superior mechanical properties. This work provides novel and new fundamental information about the processes and mechanisms that control and change crystal growth during the switch to microcrystalline domains when the second outer layer forms.

Control of Escherichia coli in Poultry Using the In Ovo Injection Technique

Pathogens, such as Escherichia coli (E. coli), have been identified as significant causes of poultry mortality. Poultry can serve as potential sources of E. coli transmission, even when asymptomatic, posing a substantial threat to food safety and human health. The in ovo administration of antimicrobials is crucial for preventing and/or effectively combating acute and chronic infections caused by poultry pathogens. To achieve this goal, it is critical that antimicrobials are properly injected into embryonic fluids, such as the amnion, to reach target tissues and trigger robust antimicrobial responses. Several protocols based on antimicrobials were evaluated to meet these requirements. This review analyzed the impacts of antimicrobial substances injected in ovo on the control of E. coli in poultry. The reduction in infection rates, resulting from the implementation of in ovo antimicrobials, combined with efforts aimed at hygienic-sanitary action plans in poultry sheds, reinforces confidence that E. coli can be contained before causing large scale damage. For example, antimicrobial peptides and probiotics have shown potential to provide protection to poultry against infections caused by E. coli. Issues related to the toxicity and bacterial resistance of many synthetic chemical compounds represent challenges that need to be overcome before the commercial application of in ovo injection protocols focused on microbiological control.

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly.

Avian obligate brood parasitic lineages evolved variable complex polycrystalline structures to build tougher eggshells

Avian brood parasites and their hosts display varied egg-puncture behaviors, exerting asymmetric co-evolutionary selection pressures on eggshells' breaking strength. We investigated eggshell structural and textural characteristics that may improve its mechanical performance. Parasitic eggshell calcified layers showed complex ultra- and microstructural patterns. However, stronger parasitic eggshells are not due to lower textural severity (characterized by lower preferred crystallographic orientation, larger local grain misorientation and smaller Kearns factor), but rather to grain boundary (GB) microstructure characteristics within the eggshell outermost layer (palisade layer, PL). Accordingly, the thicker the PL and the more complex the GB pathways are, the tougher the parasitic eggshells will be. These characteristics, which we can identify as a "GB Engineering" driven co-evolutionary process, further improve eggshell breaking strength in those parasitic species that suffer relatively high frequencies of egg-puncturing by congeneric or hosts. Overall, plain textural patterns are not suitable predictors for comparing mechanical performance of bioceramic materials.

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.

Influence of Intramineral Proteins on the Growth of Carbonate Crystals Using as a Scaffold Membranes of Ratite Birds and Crocodiles Eggshells

The lack of information on structural basis where proteins are involved, as well as the biomineralization processes of different systems such as bones, diatom frustules, and eggshells, have intrigued scientists from different fields for decades. This scientific curiosity has led to the use of methodologies that help understand the mechanism involved in the formation of these complex structures. Therefore, this work focuses on the use of eggshell membranes from different species of ratites (emu and ostrich) and reptiles (two species of crocodiles) as a model to differentiate biocalcification and biosilicification by introducing calcium phosphate or silica inside the membrane fiber mantles. We performed this to obtain information about the process of eggshell formation as well as the changes that occur in the membrane during crystal formation. In order to identify and understand the early processes leading to the formation of the microstructures present in the eggshell, we decided to carry out the synthesis of silica-carbonate of calcium, barium, and strontium called biomorph in the presence of intramineral proteins. This was carried out to evaluate the influence of these proteins on the formation of specific structures. We found that the proteins on untreated membranes, present a structural growth similar to those observed in the inner part of the eggshell, while in treated membranes, the structures formed present a high similarity with those observed in the outer and intermediate part of the eggshell. Finally, a topographic and molecular analysis of the biomorphs and membranes was performed by scanning electron microscopy (SEM), Raman and Fourier-transform Infrared (FTIR) spectroscopies.

Effects of Dietary Betaine on the Laying Performance, Antioxidant Capacity, and Uterus and Ovary Function of Laying Hens at the Late Stage of Production

Betaine has been found to alleviate oxidative stress, inflammation, and apoptosis. However, whether dietary betaine can protect late-laying hens against these adverse effects is unknown. Here, 270 65-week-old Jinghong-1 laying hens were randomly divided into the Control, 0.1% Betaine, and 0.5% Betaine groups and fed a basal diet, 0.1%, and 0.5% betaine supplemented diet, respectively. The trial lasted for seven weeks. Birds that consumed 0.5% betaine laid more eggs with thicker eggshells. Accordingly, uterine reduced glutathione (GSH), glutathione peroxidase (GSH-PX), and ovarian superoxide dismutase (SOD) contents were increased. The uterine calcium ion content and the mRNA expression of ovalbumin, ovotransferrin, and carbonic anhydrase two were increased. Moreover, ovarian IL-1β, Caspase-1, Caspase-8, and Caspase-9 mRNA expressions were decreased; luteinising hormone receptor (LHR) and follicle-stimulating hormone receptor mRNA expressions were increased. Furthermore, dietary betaine decreased the ovaries' mRNA expression of DNA methyltransferase 1 (DNMT)1, DNMT3a, and DNMT3b. The methylation level at the promoter region of ovarian LHR decreased. These results indicated that dietary betaine consumption with a concentration of 0.5% could increase the laying rate and the eggshell thickness during the late-laying period. The underlying mechanism may include antioxidative, anti-apoptosis, and hormone-sensitivity-enhancing properties.

Dietary cholecalciferol and 25-hydroxycholecalciferol supplementation interact to modulate reproductive performance, egg quality, serum antioxidant capacity, intestinal morphology and tibia quality of breeder geese

1. A study was conducted to evaluate the effects of dietary cholecalciferol (vitamin D3) and 25-hydroxycholecalciferol (25-OH-D3) supplementation on the reproductive performance, egg quality, eggshell ultrastructure, serum hormone level and antioxidant capacity, intestinal morphology and tibia quality of breeder geese during the laying period.2. The trial was designed as a 3 × 3 factorial arrangement with three levels (300, 400 and 500 IU/kg) of vitamin D3 supplementation and three levels (25, 50 and 75 μg/kg) of 25-OH-D3 supplementation in a 10-wk feeding trial.3. The results showed that the combined supplementation of 400 IU/kg vitamin D3 and 50 μg/kg 25-OH-D3 had a better feed conversion ratio and a higher egg laying rate than the other groups. Vitamin D3 supplementation significantly increased the rate of qualified eggs for hatching, eggshell strength and thickness, serum testosterone and progesterone levels, serum total superoxide dismutase and glutathione peroxidase activities, tibia ash content and bone mineral density (P < 0.05). Dietary 25-OH-D3 supplementation significantly increased serum glutathione peroxidase activity and duodenal villus height and villus height-to-crypt-depth ratio (P < 0.05). The geese receiving 500 IU/kg vitamin D3 and 75 µg/kg 25-OH-D3 had the highest tibia calcium and phosphorous content among all groups (P < 0.05).4. Feeding 400 IU/kg vitamin D3 plus 50 µg/kg 25-OH-D3 gave optimal effects on feed conversion ratio and egg laying rate. This combination could be a nutritional strategy for increasing the laying rate, eggshell quality, serum hormone levels and serum antioxidant function regardless of 25-OH-D3 supplementation. Supplementation of 50 μg/kg 25-OH-D3 could be a recommended dose for improving the serum antioxidant capacity and intestinal morphology regardless of vitamin D3 supplementation.

Effect of translucency and eggshell color on broiler breeder egg hatchability and hatch chick weight

A successful hatch has a considerable economic impact on all poultry companies. The aim of the current study was to describe the possible effects of shell translucency (T score) and coloration lightness (L* value) on shell thickness, hatchability, and chick weight. A total of 4,320 eggs from 4 commercial Ross 708 breeder flocks (50-55-wk old) were used. Eggs were selected for T score and L* value. A 3-point subjective scoring system was used for T score (1 = low, 2 = medium, 3 = high), and an electronic colorimeter for L* value, sorting the eggs as light (avg. L* = 80.7) or dark (avg. L* = 76.0). Data were analyzed using the GLIMMIX procedure of SAS (V9.4) and Tukey's HSD test was performed to separate means, a significant difference was considered when P ≤ 0.05. Results suggest that the color of the eggshell was related to the egg weight on the day of collection (P = 0.0056) and at transfer (P = 0.0211), in both cases dark eggs were 0.6 g heavier than light eggs. Dark eggs had a 3.8% increased hatchability of egg set (P = 0.0481) and yielded 6 µm thicker shells (P = 0.0019) when compared to light eggs. Regarding translucency, egg weight at transfer was 0.8 g heavier for T score 1 eggs compared to T score 3 (P = 0.0358). The translucency score of 1 had a 6.9% higher hatchability of eggs set (P = 0.0127) and 0.7 g heavier chick weight (P = 0.0385) compared to T score 3. However, T score 1 eggs had shells 28 µm thinner than the T score 2 and 34 µm thinner than T score 3 (P < 0.0001). An interaction effect was observed for eggshell thickness, L* value, and T score, where eggs classified as light with T score 1 had thinner eggshells compared to those that were dark with T score 3 (P = 0.0292). These results suggest that eggshell translucency and coloration lightness can be good noninvasive indicators of eggshell thickness, hatchability, and chick weight in broiler breeder flocks.

Microbially Induced Calcium Carbonate Precipitation by Sporosarcina pasteurii: a Case Study in Optimizing Biological CaCO3 Precipitation

Current production of traditional concrete requires enormous energy investment that accounts for approximately 5 to 8% of the world's annual CO2 production. Biocement is a building material that is already in industrial use and has the potential to rival traditional concrete as a more convenient and more environmentally friendly alternative. Biocement relies on biological structures (enzymes, cells, and/or cellular superstructures) to mineralize and bind particles in aggregate materials (e.g., sand and soil particles). Sporosarcina pasteurii is a workhorse organism for biocementation, but most research to date has focused on S. pasteurii as a building material rather than a biological system. In this review, we synthesize available materials science, microbiology, biochemistry, and cell biology evidence regarding biological CaCO3 precipitation and the role of microbes in microbially induced calcium carbonate precipitation (MICP) with a focus on S. pasteurii. Based on the available information, we provide a model that describes the molecular and cellular processes involved in converting feedstock material (urea and Ca2+) into cement. The model provides a foundational framework that we use to highlight particular targets for researchers as they proceed into optimizing the biology of MICP for biocement production.

To Prevent Oxidative Stress, What about Protoporphyrin IX, Biliverdin, and Bilirubin?

The pigments responsible for eggshell color and patterning in birds are protoporphyrin IX (PP) and biliverdin (BV). Both are involved in the catalytic degradation of the hemo group. Bilirubin (BR), another pigment, is produced when BV is broken down. PP, BV, and BR are free radical scavengers. In this study, we theoretically investigated the antioxidant capacities of these three biological meaningful molecules using Density Functional Theory calculations. First, two antioxidant mechanisms were analyzed for PP, BV, and BR: electron transfer and Hydrogen Atom Transfer. Second, since PP and BV interact with the calcium carbonate matrix of the eggshell, we analyzed the interaction of these pigments with Ca2+ and investigated their chelate compounds. Third, we explored the pro-oxidant properties of PP and BV, which have been proposed for PP when photoactivated to the triplet state, but not for BV. Our results show that PP, BV, and BR are just as good antiradical as other important natural pigments (carotenoids). Neither the antiradical properties of PP and BV nor the UV-visible spectra change due to the presence of calcium, suggesting that the signaling function of these pigments is not affected by the link with Ca2+. Finally, we found that both PP and BV (alone and when linked to Ca2+) can transfer energy from its triplet state to molecular-oxygen-producing singlet oxygen, indicating their pro-oxidant capacity. This investigation answers important questions about the function of these pigments, which may help to understand their influence on the reproductive success of birds.

Targeting the Interplay of Independent Cellular Pathways and Immunity: A Challenge in Cancer Immunotherapy

Immunotherapy is a cancer treatment that exploits the capacity of the body's immune system to prevent, control, and remove cancer. Immunotherapy has revolutionized cancer treatment and significantly improved patient outcomes for several tumor types. However, most patients have not benefited from such therapies yet. Within the field of cancer immunotherapy, an expansion of the combination strategy that targets independent cellular pathways that can work synergistically is predicted. Here, we review some consequences of tumor cell death and increased immune system engagement in the modulation of oxidative stress and ubiquitin ligase pathways. We also indicate combinations of cancer immunotherapies and immunomodulatory targets. Additionally, we discuss imaging techniques, which are crucial for monitoring tumor responses during treatment and the immunotherapy side effects. Finally, the major outstanding questions are also presented, and directions for future research are described.

Active sampling of volatile chemicals for non-invasive classification of chicken eggs by sex early in incubation

According to industry estimates, approximately 7 billion day-old male chicks are disposed of annually worldwide because they are not of use to the layer industry. A practical process to identify the sex of the egg early in incubation without penetrating the egg would improve animal welfare, reduce food waste and mitigate environmental impact. We implemented a moderate vacuum pressure system through commercial egg-handling suction cups to collect volatile organic compounds (VOCs). Three separate experiments were set up to determine optimal conditions to collect eggs VOCs to discriminate male from female embryos. Optimal extraction time (2 min), storage conditions (short period of incubation during egg storage (SPIDES) at days 8-10 of incubation), and sampling temperature (37.5°C) were determined. Our VOC-based method could correctly differentiate male from female embryos with more than 80% accuracy. These specifications are compatible with the design of specialized automation equipment capable of high-throughput, in-ovo sexing based on chemical sensor microchips.

Evidence for heterothermic endothermy and reptile-like eggshell mineralization in Troodon, a non-avian maniraptoran theropod

The dinosaur-bird transition involved several anatomical, biomechanical, and physiological modifications of the theropod bauplan. Non-avian maniraptoran theropods, such as Troodon, are key to better understand changes in thermophysiology and reproduction occurring during this transition. Here, we applied dual clumped isotope (Δ47 and Δ48) thermometry, a technique that resolves mineralization temperature and other nonthermal information recorded in carbonates, to eggshells from Troodon, modern reptiles, and modern birds. Troodon eggshells show variable temperatures, namely 42 and 29 ± 2 °C, supporting the hypothesis of an endothermic thermophysiology with a heterothermic strategy for this extinct taxon. Dual clumped isotope data also reveal physiological differences in the reproductive systems between Troodon, reptiles, and birds. Troodon and modern reptiles mineralize their eggshells indistinguishable from dual clumped isotope equilibrium, while birds precipitate eggshells characterized by a positive disequilibrium offset in Δ48. Analyses of inorganic calcites suggest that the observed disequilibrium pattern in birds is linked to an amorphous calcium carbonate (ACC) precursor, a carbonate phase known to accelerate eggshell formation in birds. Lack of disequilibrium patterns in reptile and Troodon eggshells implies these vertebrates had not acquired the fast, ACC-based eggshell calcification process characteristic of birds. Observation that Troodon retained a slow reptile-like calcification suggests that it possessed two functional ovaries and was limited in the number of eggs it could produce; thus its large clutches would have been laid by several females. Dual clumped isotope analysis of eggshells of extinct vertebrates sheds light on physiological information otherwise inaccessible in the fossil record.

Potential Utilization of Ground Eggshells as a Biofiller for Natural Rubber Biocomposites

The aim of this work was application of ground eggshells in various amounts by weight as a biofiller for natural rubber (NR) biocomposites. Cetyltrimethylammonium bromide (CTAB), ionic liquids (ILs), i.e., 1-butyl-3-methylimidazolium chloride (BmiCl) and 1-decyl-3-methylimidazolium bromide (DmiBr), and silanes, i.e., (3-aminopropyl)-triethoxysilane (APTES) and bis [3-(triethoxysilyl)propyl] tetrasulfide (TESPTS), were used to increase the activity of ground eggshells in the elastomer matrix and to ameliorate the cure characteristics and properties of NR biocomposites. The influence of ground eggshells, CTAB, ILs, and silanes on the crosslink density, mechanical properties, and thermal stability of NR vulcanizates and their resistance to prolonged thermo-oxidation were explored. The amount of eggshells affected the curing characteristics and crosslink density of the rubber composites and therefore their tensile properties. Vulcanizates filled with eggshells demonstrated higher crosslink density than the unfilled sample by approximately 30%, whereas CTAB and ILs increased the crosslink density by 40-60% compared to the benchmark. Owing to the enhanced crosslink density and uniform dispersion of ground eggshells, vulcanizates containing CTAB and ILs exhibited tensile strength improved by approximately 20% compared to those without these additives. Moreover, the hardness of these vulcanizates was increased by 35-42%. Application of both the biofiller and the tested additives did not significantly affect the thermal stability of cured NR compared to the unfilled benchmark. Most importantly, the eggshell-filled vulcanizates showed improved resistance to thermo-oxidative aging compared to the unfilled NR.

Adjusting phosphate feeding regimen according to daily rhythm increases eggshell quality via enhancing medullary bone remodeling in laying hens

BACKGROUND

Body phosphorus metabolism exhibits a circadian rhythm over the 24-h daily cycle. The egg laying behavior makes laying hens a very special model for investigating phosphorus circadian rhythms. There is lack of information about the impact of adjusting phosphate feeding regimen according to daily rhythm on the phosphorus homeostasis and bone remodeling of laying hens.

METHODS AND RESULTS

Two experiments were conducted. In Exp. 1, Hy-Line Brown laying hens (n = 45) were sampled according the oviposition cycle (at 0, 6, 12, and 18 h post-oviposition, and at the next oviposition, respectively; n = 9 at each time point). Diurnal rhythms of body calcium/phosphorus ingestions and excretions, serum calcium/phosphorus levels, oviduct uterus calcium transporter expressions, and medullary bone (MB) remodeling were illustrated. In Exp. 2, two diets with different phosphorus levels (0.32% and 0.14% non-phytate phosphorus (NPP), respectively) were alternately presented to the laying hens. Briefly, four phosphorus feeding regimens in total (each included 6 replicates of 5 hens): (1) fed 0.32% NPP at both 09:00 and 17:00; (2) fed 0.32% NPP at 09:00 and 0.14% NPP at 17:00; (3) fed 0.14% NPP at 09:00 and 0.32% NPP at 17:00; (4) fed 0.14% NPP at both 09:00 and 17:00. As a result, the regimen fed 0.14% NPP at 09:00 and 0.32% NPP at 17:00, which was designed to strengthen intrinsic phosphate circadian rhythms according to the findings in Exp. 1, enhanced (P < 0.05) MB remodeling (indicated by histological images, serum markers and bone mineralization gene expressions), elevated (P < 0.05) oviduct uterus calcium transportation (indicated by transient receptor potential vanilloid 6 protein expression), and subsequently increased (P < 0.05) eggshell thickness, eggshell strength, egg specific gravity and eggshell index in laying hens.

CONCLUSIONS

These results underscore the importance of manipulating the sequence of daily phosphorus ingestion, instead of simply controlling dietary phosphate concentrations, in modifying the bone remodeling process. Body phosphorus rhythms will need to be maintained during the daily eggshell calcification cycle.

Physiological regulation of calcium and phosphorus utilization in laying hens

Commercial laying hens can produce one egg approximately every 24 h. During this process, regulatory systems that control vitamin D₃ metabolism, calcium and phosphorus homeostasis, and intestinal uptake of these minerals work in concert to deliver components required for eggshell calcification and bone mineralization. Commercial production cycles have been extended in recent years to last through 100 weeks of age, and older hens often exhibit an increased prevalence of skeletal fractures and poor eggshell quality. Issues such as these arise, in part, through imbalances that occur in calcium and phosphorus utilization as hens age. As a result, an in-depth understanding of the mechanisms that drive calcium and phosphorus uptake and utilization is required to develop solutions to these welfare and economic challenges. This paper reviews factors that influence calcium and phosphorus homeostasis in laying hens, including eggshell formation and development and roles of cortical and medullary bone. Metabolism and actions of vitamin D₃ and physiological regulation of calcium and phosphorus homeostasis in key tissues are also discussed. Areas that require further research in avian species, such as the role of fibroblast growth factor 23 in these processes and the metabolism and action of bioactive vitamin D₃, are highlighted and the importance of using emerging technologies and establishing in vitro systems to perform functional and mechanistic studies is emphasized.

Lonicera flos and Cnicus japonicus extracts improved egg quality partly by modulating antioxidant status, inflammatory-related cytokines and shell matrix protein expression of oviduct in laying hens

This study was conducted to investigate the effects of Lonicera flos and Cnicus japonicus extracts (LCE) on the laying performance, egg quality, morphology, antioxidant status, inflammatory-related cytokines, and shell matrix protein expression of oviduct in laying hens. A total of 1,728 Roman Pink laying hens aged 73-wk-old were randomly assigned into 4 groups (18 replicates/group, 24 layers/replicate) fed basal diets supplemented with 0, 300, 500, and 1,000 mg of LCE per kg of diet, respectively. The trial lasted for 11 wk, including 2-wk adjustment period and 9-wk testing period. The results indicated that laying hens fed diets supplemented with LCE linearly increased egg weight, yolk color and shell thickness at wk 78 and albumen height, Haugh unit and shell thickness at wk 83 (P < 0.05). At wk 78, LCE groups linearly affected the hydrogen peroxide content in magnum (P < 0.05) and 300 mg/kg LCE groups had the highest catalase activity in isthmus (P < 0.05). At wk 83, LCE groups linearly reduced (P < 0.05) hydrogen peroxide content in the magnum and isthmus and malondialdehyde content in the uterus whereas increased catalase activity in isthmus (P < 0.05). Furthermore, LCE levels quadratically affected glutathione peroxidase activity in isthmus at wk 83 (P < 0.05). At wk 78, the mRNA expressions of inducible nitric oxide synthase and interferon-γ in isthmus and ovalbumin and ovocleidin-116 in uterus had linear effects in response to LCE levels (P < 0.05) and 1,000 mg/kg LCE group had the lowest mRNA expression of interleukin-6 in magnum (P < 0.05). At wk 83, LCE supplementation linearly decreased the mRNA expression of interleukin-1β, interferon-γ and tumor necrosis factor-α in magnum and tumor necrosis factor-α and inducible nitric oxide synthase in uterus (P < 0.05). It is concluded that LCE improved egg quality partly by modulating antioxidant status, inflammatory-related cytokines and shell matrix protein expression of oviduct in laying hens.

Effects of Dietary Supplementation of arginine-silicate- Inositol and Phytase Complex on Egg Quality, Egg Shell Strength, and Blood Biochemical Characteristics of Laying Hens

This study aimed to determine the effects of Arginine silicate inositol complex (ASI; Arg=49.47 %, silicone=8.2 %, inositol=25%) supplementation on egg quality, shell strength, and blood biochemical traits of laying hens, as well as the effects of substituting inositol with varying concentrations of phytase on the traits as mentioned above. 90 Lohmann Brown laying hens, 26 weeks old, were randomly distributed in 6 treatments with 3 replicates (cage) and 5 birds per replicate. The isocaloric and isonitrogenic diets are used according to the age period requirements of the Lohmann Brown Classic management guideline. The treatments were as follows: 1ST treatment T1: received basal diet without additives, T2 received basal diet +1000 mg/kg arginine-silicate mixture (49.5±8.2 % respectively), T3 received basal diet +1000 mg/kg arginine-silicate- inositol (ASI) mixture (49.5, 8.2 , 25 % respectively), T4 received basal diet +1000 mg/kg arginine-silicate mixture (49.5±8.2% respectively) +500 FTU/kg, T5 received basal diet +1000 mg/kg arginine-silicate mixture (49.5±8.2% respectively) +1000 FTU/kg and T6 received basal diet +1000 mg/kg arginine-silicate mixture (49.5±8.2% respectively) +1000 FTU/kg +2000 FTU/kg. Results indicate a significant increase (P<0.05) in the relative yolk weight in T4, T5, and T6 (26.93, 26.83, 26.77%) compared to T1 (25.84%) and a significant increase (P≤ 0.05) in T4, T5 compared to T3 (26.02%), while no differences observed between T2 (26.17%) compared to other experimental treatments. The relative albumin weight significantly decreased (P≤0.05) in phytase supplementation treatments T4, T5, and T6 (63.21, 63.05, 63.22%) compared to T1, T2, T3 (64.99, 64.30, 64.08%), while a significant decrease (P≤0.05) observed in T3 compared to T1. The relative shell weight significantly increased (P≤0.05) in T3, T4, T5, and T6 (9.90, 9.86, 10.12, 10.02%), respectively, compared to T1, T2 (9.17, 9.53%) with a significant increase (P≤0.05) in relative shell weight in T2 compared to T1. The eggshell thickness significantly increased (P≤0.05) in T3, T4, T5, T6 treatments (0.409, 0.408, 0.411, 0.413 mm), respectively compared to T1, T2 (0.384, 0.391 mm). A significant increased (P≤0.05) was observed in eggshell thickness in T2 compared to T1. A significant increase (P≤0.05) was observed in the egg shell breaking strength in T3 and T5 treatments (59.40, 58.83) compared to T1 and T2 (46.20, 48.23). No significant differences were observed between T4 and T6 (53.90, 53.57) compared to other experimental treatments. Non HDL, calcium, and phosphorus levels in blood serum significantly increased (P≤0.05) in T3, T4, T5, and T6 treatments compared to T1 and T2 treatments.

Preparation and Stability of Monodisperse Amorphous CaCO3 Microspheres of High Hardness and Sphericity

Using amorphous CaCO₃ (ACC) to biomimic the crustacean exoskeleton and optimize the physical and chemical properties of the polymeric phase of ACC holds great promise. Controlling the ACC morphology and stability is key in this process. For this article, monodisperse ACC microspheres, with a high sphericity of 0.973 ± 0.001 and a hardness of 0.6755 GPa, were prepared using the gas diffusion method in the presence of Mg²⁺. Their hardness is 3.58-16 times greater than that ever reported before for ACC microspheres. The stability of ACC is strongly affected by environmental conditions. The liquid phase and high temperature are not conducive to its stability, but ACC microspheres do have high stability under ambient conditions. After 100 days under such conditions, only a small amount of crystallization occurs, and their spherical shape survives intact. This article provides guidance for the preparation of ACC biomimetic composites, sheds light on the biological function of ACC in crustacean exoskeletons, and improves the theoretical understanding of the mechanism of biomineralization.

Effects of feeding strategies on eggshell quality of laying hens during late laying period

Insufficient calcium supply during the dark period is an important reason for deteriorated eggshell quality in laying hens. In the present study, the feeding time of hens was altered in order to investigate whether the changes in feeding time and feed consumption could influence the laying performance and eggshell quality of hens. A total of 192, 60-wk-old Hy-line Brown hens with similar body weight and laying rate were obtained. The hens were randomly divided into 4 groups and subjected to the following feeding strategies: feeding 3 times a day (control group, CON), or feeding once a day in the morning at 08:00 (MF), in the noon at 12:00 (NF), or in the afternoon at 16:00 (AF), respectively. The feeding strategies had no significant effect (P > 0.05) on laying rate, egg weight, and egg mass. Although the feed intake did not differ among treatments, the time phase of feed consumption was changed. From 15:00 to 21:00 h, hens consumed 49.7%, 42.4%, 49.1%, and 70.8% of daily feed intake in the CON, MF, NF, and AF groups, respectively. Feeding strategy had no detectable influence (P > 0.05) on egg shape index, eggshell strength, and eggshell percentage. Compared to CON, AF hens tended to have a higher eggshell thickness (P = 0.053). In MF and NF treatments, plasma calcium (Ca), phosphorus (P) levels, and alkaline phosphatase (ALP) activity did not differ (P > 0.05) compared with CON. In contrast, AF-hens had lower Ca and P levels, but a higher ALP activity than CON (P < 0.01). The AF hens had higher uterine fluid Ca than MF and NF hens (P < 0.05). Compared to CON, the expression level of CaBP-D28K was increased in the shell gland mucosa of MF-hens. Also, MF-, NF-, and AF-hens had higher Osteopontin (OPN) expression level (P < 0.05), whereas NF had a higher expression of OC-116 (P < 0.01). In conclusion, the results indicated that feeding in the afternoon changed the pattern of feed consumption and exerted a positive influence on eggshell thickness.

Functional complexity in the chorioallantoic membrane of an oviparous snake: Specializations for calcium uptake from the eggshell

The chorioallantoic membrane of oviparous reptiles forms a vascular interface with the eggshell. The eggshell contains calcium, primarily as calcium carbonate. Extraction and mobilization of this calcium by the chorioallantoic membrane contributes importantly to embryonic nutrition. Development of the chorioallantoic membrane is primarily known from studies of squamates and birds. Although there are pronounced differences in eggshell structure, squamate and bird embryos each mobilize calcium from eggshells. Specialized cells in the chicken chorionic epithelium transport calcium from the eggshell aided by a second population of cells that secrete protons generated by the enzyme carbonic anhydrase. Calcium transporting cells also are present in the chorioallantoic membrane of corn snakes, although these cells function differently than those of chickens. We used histology and immunohistology to characterize the morphology and functional attributes of the chorioallantoic membrane of corn snakes. We identified two populations of cells in the outer layer of the chorionic epithelium. Calbindin-D_28K , a cellular marker for calcium transport expressed in squamate chorioallantoic membranes, is localized in large, flattened cells that predominate in the chorionic epithelium. Smaller cells, interspersed among the large cells, express carbonic anhydrase 2, an enzyme not previously localized in the chorionic epithelium of an oviparous squamate. These findings indicate that differentiation of chorionic epithelial cells contributes to extraction and transport of calcium from the eggshell. The presence of specializations of chorioallantoic membranes for calcium uptake from eggshells in chickens and corn snakes suggests that eggshell calcium was a source of embryonic nutrition early in the evolution of Sauropsida.

Atomic Details of Biomineralization Proteins Inspiring Protein Design and Reengineering for Functional Biominerals

Biominerals are extraordinary materials that provide organisms with a variety of functions to support life. The synthesis of biominerals and organization at the macroscopic level is a consequence of the interactions of these materials with proteins. The association of biominerals and proteins is very ancient and has sparked a wealth of research across biological, medical and material sciences. Calcium carbonate, hydroxyapatite, and silica represent widespread natural biominerals. The atomic details of the interface between macromolecules and these biominerals is very intriguing from a chemical perspective, considering the association of chemical entities that are structurally different. With this review I provide an overview of the available structural studies of biomineralization proteins, explored from the Protein Data Bank (wwPDB) archive and scientific literature, and of how these studies are inspiring the design and engineering of proteins able to synthesize novel biominerals. The progression of this review from classical template proteins to silica polymerization seeks to benefit researchers involved in various interdisciplinary aspects of a biomineralization project, who need background information and a quick update on advances in the field. Lessons learned from structural studies are exemplary and will guide new projects for the imaging of new hybrid biomineral/protein superstructures at the atomic level.

Antimicrobial Proteins and Peptides in Avian Eggshell: Structural Diversity and Potential Roles in Biomineralization

The calcitic avian eggshell provides physical protection for the embryo during its development, but also regulates water and gaseous exchange, and is a calcium source for bone mineralization. The calcified eggshell has been extensively investigated in the chicken. It is characterized by an inventory of more than 900 matrix proteins. In addition to proteins involved in shell mineralization and regulation of its microstructure, the shell also contains numerous antimicrobial proteins and peptides (AMPPs) including lectin-like proteins, Bacterial Permeability Increasing/Lipopolysaccharide Binding Protein/PLUNC family proteins, defensins, antiproteases, and chelators, which contribute to the innate immune protection of the egg. In parallel, some of these proteins are thought to be crucial determinants of the eggshell texture and its resulting mechanical properties. During the progressive solubilization of the inner mineralized eggshell during embryonic development (to provide calcium to the embryo), some antimicrobials may be released simultaneously to reinforce egg defense and protect the egg from contamination by external pathogens, through a weakened eggshell. This review provides a comprehensive overview of the diversity of avian eggshell AMPPs, their three-dimensional structures and their mechanism of antimicrobial activity. The published chicken eggshell proteome databases are integrated for a comprehensive inventory of its AMPPs. Their biochemical features, potential dual function as antimicrobials and as regulators of eggshell biomineralization, and their phylogenetic evolution will be described and discussed with regard to their three-dimensional structural characteristics. Finally, the repertoire of chicken eggshell AMPPs are compared to orthologs identified in other avian and non-avian eggshells. This approach sheds light on the similarities and differences exhibited by AMPPs, depending on bird species, and leads to a better understanding of their sequential or dual role in biomineralization and innate immunity.

Analysis of ultrastructure and microstructure of blackbird (Turdus merula) and song thrush (Turdus philomelos) eggshell by scanning electron microscopy and X-ray computed microtomography

The unique structure of the egg allows for efficient reproduction on land. Although the functions of the egg are ensured by the concomitant cooperation of all its structures, the eggshell also plays a significant role. Apart from maintaining an aqueous environment within the egg along with controlled gas exchange, the color and pigmentation pattern of eggshell contributes to identification and protection. As a result of all these functions, the structure, shape, and pigmentation of eggshell greatly vary across the class of birds, and understanding these three variability-determining factors may aid in better interpretation of evolutionary mechanisms. In this study, we analyzed for the first time the structure, mineral composition, and characteristics of the pigmentation of blackbird (Turdus merula) and song thrush (Turdus philomelos) eggshells. The shell of blackbird eggs is much thicker compared to the shell of song thrush eggs which is due to a much thicker crystalline and palisade layers. In both species, strongly elongated mammillary knobs are observed, which create a large space between the mineralized shell and the egg membranes. The blackbird egg shell has a higher water vapor conductivity which is due to the larger diameter of the circle and the surface area of individual pores. The primary compound entering the mineral composition of the shell in both species is CaCO₃ however, the thrush egg shells contained more Mg in all layers except the crystalline layer, and S in the crystalline and palisade layers. The two species clearly differ in the size and distribution of pigment spots on the eggshell. We suppose that the differences in shell structure and pigmentation presented in this study may in the future provide a basis for explaining the reasons for the much lower reproductive efficiency of song thrush compared to blackbird.

Genome Wide Scan to Identify Potential Genomic Regions Associated With Milk Protein and Minerals in Vrindavani Cattle

In this study, genome-wide association study (GWAS) was conducted for identifying significantly associated genomic regions/SNPs with milk protein and minerals in the 96 taurine-indicine crossbred (Vrindavani) cows using 50K SNP Chip. After quality control, a total of 41,427 SNPs were retained and were further analyzed using a single-SNP additive linear model. Lactation stage, parity, test day milk yield and proportion of exotic inheritance were included as fixed effects in GWAS model. Across all traits, 13 genome-wide significant (p < 1.20 x 10⁻⁰⁶) and 49 suggestive significant (p < 2.41 x 10⁻⁰⁵) SNPs were identified which were located on 18 different autosomes. The strongest association for protein percentage, calcium (Ca), phosphorus (P), copper (Cu), zinc (Zn), and iron (Fe) were found on BTA 18, 7, 2, 3, 14, and 2, respectively. No significant SNP was detected for manganese (Mn). Several significant SNPs identified were within or close proximity to CDH13, BHLHE40, EDIL3, HAPLN1, INHBB, USP24, ZFAT, and IKZF2 gene, respectively. Enrichment analysis of the identified candidate genes elucidated biological processes, cellular components, and molecular functions involved in metal ion binding, ion transportation, transmembrane protein, and signaling pathways. This study provided a groundwork to characterize the molecular mechanism for the phenotypic variation in milk protein percentage and minerals in crossbred cattle. Further work is required on a larger sample size with fine mapping of identified QTL to validate potential candidate regions.

Liquid-Liquid Phase Separation in Nucleation Process of Biomineralization

Biomineralization is a typical interdisciplinary subject attracting biologists, chemists, and geologists to figure out its potential mechanism. A mounting number of studies have revealed that the classical nucleation theory is not suitable for all nucleation process of biominerals, and phase-separated structures such as polymer-induced liquid precursors (PILPs) play essential roles in the non-classical nucleation processes. These structures are able to play diverse roles biologically or pathologically, and could also give inspiring clues to bionic applications. However, a lot of confusion and dispute occurred due to the intricacy and interdisciplinary nature of liquid precursors. Researchers in different fields may have different opinions because the terminology and current state of understanding is not common knowledge. As a result, our team reviewed the most recent articles focusing on the nucleation processes of various biominerals to clarify the state-of-the-art understanding of some essential concepts and guide the newcomers to enter this intricate but charming field.

Myostatin Mutation in Japanese Quail Increased Egg Size but Reduced Eggshell Thickness and Strength

Simple Summary

Avian eggs provide huge benefits to both science and society by providing an important model for developmental studies and a high-quality protein source for the human diet. Especially, the hard-shell layer existing at the outer part of eggs is a unique characteristic, which is exclusive in avian species compared to other egg-laying species. Among various avian models developed to investigate genetic factors for potential industrial application, myostatin (MSTN) mutations in quail and chickens were recently generated, resulting in improved meat yield. In addition to previously reported growth and egg production traits in MSTN mutant quail, eggshell quality of mutants was further investigated in this study. Although eggshell height, width, and weight were increased by the MSTN mutation, eggshell breaking strength (EBS) and eggshell thickness were decreased in mutant eggs compared to wild-type eggs. Although these data indicated that decreased eggshell thickness contributed to decreased EBS in mutant eggs, the cellular mechanism of thinner eggshell formation in uterus by MSTN mutation needs to be further investigated using MSTN mutant quail.

Abstract

Recently developed myostatin (MSTN) mutant quail and chickens demonstrated similar effects of MSTN on muscle and fat developments between avian and mammalian species. However, the effect of MSTN mutation on the quality of eggshells, an important avian specific characteristic, has not yet been investigated although egg production traits of mutant quail have been studied. In this study, several parameters for eggshell quality, including eggshell size, eggshell weight, eggshell breaking strength (EBS), and eggshell thickness, were all compared between MSTN mutant and wild-type (WT) eggs. MSTN mutant eggs had greater height and width along with heavier eggshell weight compared to WT eggs, which shows proportional improvement in egg size as affected by the MSTN mutation. However, EBS and eggshell thickness were decreased in mutant eggs compared to WT eggs. In addition, the palisade layer, the thickest and most important layer for the strength of an eggshell, was also decreased without a change in the number of vesicular holes. These data indicated that decreases in the thickness of the eggshell and the palisade layer would be a main factor contributing to a lower EBS in mutant eggs. MSTN mutant quail provide a useful model to better understand the function of MSTN on avian uterine cell development and eggshell biomineralization.

Lignin-Induced CaCO3 Vaterite Structure for Biocatalytic Artificial Photosynthesis

The vaterite phase of CaCO₃ exhibits unique characteristics, such as high porosity, surface area, dispersivity, and low specific gravity, but it is the most unstable polymorph. Here, we report lignin-induced stable vaterite as a support matrix for integrated artificial photosynthesis through the encapsulation of key active components such as the photosensitizer (eosin y, EY) and redox enzyme (l-glutamate dehydrogenase, GDH). The lignin-vaterite/EY/GDH photobiocatalytic platform enabled the regeneration of the reduced nicotinamide cofactor under visible light and facilitated the rapid conversion of α-ketoglutarate into l-glutamate (initial conversion rate, 0.41 mM h^-1; turnover frequency, 1060 h^-1; and turnover number, 39,750). The lignin-induced vaterite structure allowed for long-term protection and recycling of the active components while facilitating the photosynthesis reaction due to the redox-active lignin. Succession of stability tests demonstrated a significant improvement of GDH's robustness in the lignin-vaterite structure against harsh environments. This work provides a simple approach for solar-to-chemical conversion using a sustainable, integrated light-harvesting system.

Eggshell decalcification and skeletal mineralization during chicken embryonic development: defining candidate genes in the chorioallantoic membrane

During chicken embryonic development, skeleton calcification mainly relies on the eggshell, whose minerals are progressively solubilized and transported to the embryo via the chorioallantoic membrane (CAM). However, the molecular components involved in this process remain undefined. We assessed eggshell demineralization and calcification of the embryo skeleton after 12 and 16 d of incubation, and analyzed the expression of several candidate genes in the CAM: carbonic anhydrases that are likely involved in secretion of protons for eggshell dissolution (CA2, CA4, CA9), ions transporters and regulators (CALB1, SLC4A1, ATP6V1B2, SGK1, SCGN, PKD2) and vitamin-D binding protein (GC).

Our results confirmed that eggshell weight, thickness, and strength decreased during incubation, with a concomitant increase in calcification of embryonic skeletal system. In the CAM, the expression of CA2 increased during incubation while CA4 and CA9 were expressed at similar levels at both stages. SCL4A1 and SCGN were expressed, but not differentially, between the two stages, while the expression of ATP6V1B2 and PKD2 genes decreased. The expression of SGK1 and TRPV6 increased over time, although the expression of the latter gene was barely detectable. In parallel, we analyzed the expression of these candidate genes in the yolk sac (YS), which mediates the transfer of yolk minerals to the embryo during the first half of incubation. In YS, CA2 expression increases during incubation, similar to the CAM, while the expression of the other candidate genes decreases. Moreover, CALB1 and GC genes were found to be expressed during incubation in the YS, in contrast to the CAM where no expression of either was detected.

This study demonstrates that the regulation of genes involved in the mobilization of egg minerals during embryonic development is different between the YS and CAM extraembryonic structures. Identification of the full suite of molecular components involved in the transfer of eggshell calcium to the embryo via the CAM should help to better understand the role of this structure in bone mineralization.

Effect of 25-hydroxyvitamin D and essential oil complex on productive performance, egg quality, and uterus antioxidant capacity of laying hens

This study was conducted to determine the effect of 25-hydroxyvitamin D (HDV) and essential oils (EO) on the uterus antioxidant capacity, egg quality, and eggshell ultrastructure in laying hens. A total of 400 48-wk-old Lohmann laying hens were randomly allocated into 2 groups and fed a basal diet (control) or a basal diet supplemented with a combination of 69 μg/kg HDV and EO (including 200 mg/kg thymol and 50 mg/kg carvacrol) for 12 wk. There are 10 replicates of 20 hens each. Compared with the control, dietary HDV+EO supplementation improved (P < 0.05) egg production rate, feed efficiency, eggshell thickness and strength, and decreased (P < 0.05) the translucent egg score. Ultrastructural changes indicated that dietary HDV+EO supplementation decreased (P < 0.05) mammillary knob width, mammillary thickness and the proportion of mammillary thickness, and increased (P < 0.05) the proportion of effective thickness and total thickness of the eggshells compared with the control. Supplementation with HDV+EO complex led to higher serum HDV concentration and increased antioxidant capacity in the uterus, indicated by higher (P < 0.05) antioxidant enzyme activities (catalase [CAT], total antioxidant capacity [T-AOC], and glutathione S-transferases [GST]) and lower malondialdehyde (MDA) content. Therefore, dietary HDV and EO complex (including thymol and carvacrol) supplementation can improve the productive performance and the eggshell quality in laying hens, and the improving effect on eggshell quality may through enhancing eggshell ultrastructure and antioxidant capacity of uterus.

Comparison between different breeds of laying hens in terms of eggshell translucency and its distribution in various ends of the eggshell

Eggshell translucency is a ubiquitous external eggshell quality problem caused by variations of eggshell ultrastructure or shell membrane. In previous studies, researchers have widely investigated this phenomenon with nutritional, environmental, and genetic perspectives in many breeds. However, most studies referring to phenotypic measurement of shell translucency have been performed using a relatively subjective two-, three-, or four-grading methods, which made it impossible to compare distribution of shell translucency among different breeds. In this study, we aimed to explore variations of translucent eggshell spots in different breeds and their distribution in blunt, middle, and sharp ends of eggshell using a relatively objective grayscale recognition method. We selected 45 eggs from each flock of pure lines, commercial strains, and Chinese local breeds (10 flocks, aged 60 to 70 wk), and stored them in a constant environment for 5 d. Then measured eggshell translucency using grayscale recognition method. Indicators of shell translucency included sum of spot areas on the whole eggshell (SUSA), sum area of the whole eggshell (SUSHA), RSS (ratio of SUSA to SUSHA), quantity of spots (QS), average spot area in eggshell (AAES), and diameter of spots in eggshell (DS). As results, in Hy-Line Brown, Brown-Egg Dwarf Layer, and Taihang (pink-shelled) breeds, phenotypic intensity of eggshell translucency was slight; in Rhode Island Red, Jingfen-1, and Dongxiang breeds, phenotypic intensity of eggshell translucency was relatively extensive; and in Jinghong-1, Hy-Line Sonia, White Leghorn, and Taihang (blue-shelled), phenotypic intensity of eggshell translucency was at an intermediate level. In general, the larger the RSS, the larger the QS, AAES, and DS. Of 3 ends for most breeds, eggshell translucency of blunt and sharp ends was usually greater than that of middle ends, and blunt ends seemed to have the most extensive eggshell translucency. Findings from this study could provide a reference for population selection to locate genes regulating shell translucency and to explore the physical structure mechanism for eggshell translucency formation.

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).

How much calcium to shell out? Eggshell calcium carbonate content is greater in birds with thinner shells, larger clutches and longer lifespans

The avian eggshell is a bio-ceramic structure that protects the embryo. It is composed almost entirely of calcium carbonate and a small amount of organic material. An optimal amount of calcium carbonate in the eggshell is essential for the embryo's development, yet how the ratio of calcium carbonate to organic matter varies between species has not been investigated. Calcium is a limiting resource for most birds, so its investment in their eggs should be optimized for a bird's life history. We measured the relative calcium carbonate content of eggshells in 222 bird species and tested hypotheses for how this trait has evolved with the life-history strategies of these species and other traits of their respective egg physiologies. We found that (i) eggshell calcium carbonate content was positively correlated with species having thinner eggshells and smaller than expected eggs relative to incubating parental mass, (ii) species with small mean clutch sizes had lower calcium carbonate content in their eggshells, and (iii) for species with larger clutch sizes, eggshell calcium carbonate content was negatively correlated with their mean lifespan. The pattern of lower eggshell calcium carbonate in longer lived, larger clutched birds suggests that calcium provision to the eggshell has long-term costs for the individual.

Uterine structure and function contributes to the formation of the sandpaper-shelled eggs in laying hens

The avian eggshell is formed in the uterus, and eggshell quality usually decreases markedly in the late phase of hen laying cycles. Production of sandpaper-shelled eggs (SE), a category of eggs with relatively less eggshell quality, causes a great economic loss. Underlying mechanisms of SE formation, however, remain unclear. For the present study, it was hypothesized that alterations in uterine structure and function contribute to SE formation. To test this hypothesis, uterine samples were collected from 450-day-old hens that produced normal eggs (NE) and SE (based on 2-week-long assessments, n = 10) for histomorphological and transcriptome analyses. Compared with the NE group, uteri of the SE group were apparently atrophied. Furthermore, a total of 211 differentially expressed genes (DEGs) were identified in the uteri of hens of the two groups. These DEGs were clustered into 145 gene ontology terms (FDR < 0.05) and enriched in 12 KEGG pathways (P < 0.10), which are primarily related to organ morphogenesis and development, cell growth, differentiation and death, ion transport, endocrine and cell communication, immune response, and corticotropin-releasing hormones. In particular, corticotropin may be an important factor in SE formation because of effects on ion transport. Furthermore, as indicated by lesser abundances of relevant mRNA transcripts, the lesser expression of genes related to ion transport and matrix proteins also contribute to SE production because of effects on eggshell formation. In conclusion, results from this study revealed there were structural and functional differences in the hen uterus in NE and SE groups.

Forced Biomineralization: A Review

Biologically induced and controlled mineralization of metals promotes the development of protective structures to shield cells from thermal, chemical, and ultraviolet stresses. Metal biomineralization is widely considered to have been relevant for the survival of life in the environmental conditions of ancient terrestrial oceans. Similar behavior is seen among extremophilic biomineralizers today, which have evolved to inhabit a variety of industrial aqueous environments with elevated metal concentrations. As an example of extreme biomineralization, we introduce the category of "forced biomineralization", which we use to refer to the biologically mediated sequestration of dissolved metals and metalloids into minerals. We discuss forced mineralization as it is known to be carried out by a variety of organisms, including polyextremophiles in a range of psychrophilic, thermophilic, anaerobic, alkaliphilic, acidophilic, and halophilic conditions, as well as in environments with very high or toxic metal ion concentrations. While much additional work lies ahead to characterize the various pathways by which these biominerals form, forced biomineralization has been shown to provide insights for the progression of extreme biomimetics, allowing for promising new forays into creating the next generation of composites using organic-templating approaches under biologically extreme laboratory conditions relevant to a wide range of industrial conditions.

Evolution of the Avian Eggshell Biomineralization Protein Toolkit - New Insights From Multi-Omics

The avian eggshell is a remarkable biomineral, which is essential for avian reproduction; its properties permit embryonic development in the desiccating terrestrial environment, and moreover, are critically important to preserve unfertilized egg quality for human consumption. This calcium carbonate (CaCO₃) bioceramic is made of 95% calcite and 3.5% organic matrix; it protects the egg contents against microbial penetration and mechanical damage, allows gaseous exchange, and provides calcium for development of the embryonic skeleton. In vertebrates, eggshell occurs in the Sauropsida and in a lesser extent in Mammalia taxa; avian eggshell calcification is one of the fastest known CaCO₃ biomineralization processes, and results in a material with excellent mechanical properties. Thus, its study has triggered a strong interest from the researcher community. The investigation of eggshell biomineralization in birds over the past decades has led to detailed characterization of its protein and mineral constituents. Recently, our understanding of this process has been significantly improved using high-throughput technologies (i.e., proteomics, transcriptomics, genomics, and bioinformatics). Presently, more or less complete eggshell proteomes are available for nine birds, and therefore, key proteins that comprise the eggshell biomineralization toolkit are beginning to be identified. In this article, we review current knowledge on organic matrix components from calcified eggshell. We use these data to analyze the evolution of selected matrix proteins and underline their role in the biological toolkit required for eggshell calcification in avian species. Amongst the panel of eggshell-associated proteins, key functional domains are present such as calcium-binding, vesicle-binding and protein-binding. These technical advances, combined with progress in mineral ultrastructure analyses, have opened the way for new hypotheses of mineral nucleation and crystal growth in formation of the avian eggshell, including transfer of amorphous CaCO₃ in vesicles from uterine cells to the eggshell mineralization site. The enrichment of multi-omics datasets for bird species is critical to understand the evolutionary context for development of CaCO₃ biomineralization in metazoans, leading to the acquisition of the robust eggshell in birds (and formerly dinosaurs).