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PubMed1984

Development of calcium reabsorption by the allantoic epithelium in chick embryos grown in shell-less culture.

The allantoic sac of the chick embryo functions as a primitive urinary bladder, storing and modifying the excretory fluid produced by the embryo. We have used chick embryos grown in shell-less culture to study the in situ handling of Ca2+ by the allantoic epithelium. Between Days 8 and 13 of incubation (38 degrees C, 5% CO2), the [Ca2+] of the allantoic sac fluid declines from about 1.5 mM to less than 0.3 mM, with most of this Ca2+ reabsorption occurring between Days 10 and 11. In 13-day-old embryos, the allantoic epithelium reabsorbs within 24 hr 85-92% of 45Ca2+ injected into the allantoic sac, while in 9-day-old embryos 45Ca2+ reabsorption is less than 40% by 24 hr. This is evidence for the developmental onset of a Ca2+ reabsorption process in the allantoic epithelium. The allantoic fluid Ca2+ is reabsorbed into the embryo's blood in which the serum [Ca2+] is about 1.5 mM. Also, electrical potential profiles reveal that the serosal (mesenchymal) side of the allantoic epithelium is 15-30 mV positive compared to the mucosal (luminal) side. Thus, by electrochemical criteria this reabsorption process appears to be active.

Absorption↗
PubMed1988

Short-term effects of altered shell conductance on oxygen uptake and hematological variables of late chicken embryos.

The preceding report on the O2 uptake (MO2) of chicken embryos whose shell conductance (GO2) was altered from the beginning of incubation showed that the MO2 was decreased despite increased GO2 [Okuda, A. and H. Tazawa (1988) Respir. Physiol. 74: 187-198]. This was attributed to an excess water loss which reduced the growth of the embryos. The present study was designed to investigate the short-term effects of altered GO2, obviating the effect of excess water loss, on the MO2 and simultaneously on the hematological variables of embryos on days 16-17 and days 18-19 of incubation. The MO2 measured 5 h after increasing the GO2 was neither decreased nor increased significantly. The diffusing capacity of the chorio-allantoic membrane, which was estimated using the Bohr integration procedure, decreased as the GO2 was increased. When the GO2 was decreased, on the other hand, the decrease in MO2 was not so large as expected from the decrease in GO2, for both 16- and 18-day-old embryos. The effect of reduced GO2 on MO2 was more prominent in 18-day-old embryos than 16-day-old embryos. One-day-long hypoxia due to decreased GO2 induced erythropoiesis in 18-19-day embryos, but did not do so in 16-17-day embryos. The increase in hematocrit value of the latter group of embryos was attributed to an increase in cell volume due to concurrent hypercapnia.

Allantois↗
PubMed1988

Aeration of the shell membranes of avian eggs.

The inner and outer shell membranes (ISM, OSM) of fertile hen's eggs become aerated during the first ten days of incubation. The volume of gas in the compound membrane increases from 0 to 65% by day 11 when practically all of the space between the fibers is gas filled. The amount of gas depends on a balance between the capillary tension produced by fluid menisci in the interstices between fibers and the colloid osmotic tension of the albumen. Capillary tension, measured directly with a pressure plate apparatus, and colloid osmotic pressure, measured with a new technique, are in virtual equilibrium during aeration. These tensions increase from 0.15 bar at laying to 2.25 bar on day 11 because of evaporation from the membranes and active removal of water from the albumen by the embryo. Water leaving the membranes by evaporation is only partly replaced from the albumen. Thus the water contents of the membranes and albumen decrease (ISM: 79 to 56%, OSM: 71 to 52%, albumen: 86 to 58%). As the membranes dry, gas enters the larger pores first. Physiological estimates of effective radius show smaller (x = 1.3 micrograms), bimodally distributed pores in the ISM and larger (x = 3.4 micrograms), unimodally distributed pores in the OSM.

Animals↗
PubMed1994

Contamination of egg shell and contents with Salmonella enteritidis: a review.

Salmonella enteritidis can contaminate the contents of clean, intact shell eggs as a result of infections of the reproductive tissue of laying hens. The principal site of infection would appear to be the upper oviduct. In egg contents the most important sites of contamination are either the outside of the vitelline membrane or the albumen surrounding it. In fresh eggs, only few salmonellas are present and as albumen is an iron-restricted environment, growth will only occur once storage-related changes to vitelline membrane permeability, which allow salmonellas to invade yolk contents, have taken place. When this happens high populations are achieved in both yolk contents and albumen. Some eggs from naturally infected hens have been found to contain large numbers of S. enteritidis. The rate of change in membrane permeability is temperature-dependent. In eggs stored at 20 degrees C, yolk invasion is uncommon until eggs have been stored for 3 weeks. In stimulated kitchen conditions where temperatures reached 30 degrees C, salmonellas could grow rapidly after a few days.

Animals↗
PubMed1991

Mineral metabolism in the developing turkey embryo--I. The effects of developmental age and shell-less culture on trace element contents of selected tissues.

1. Turkey embryos were incubated in ovo or in long-term shell-less culture (ex ovo) for 14, 18, 22 or 26 days. The embryos incubated ex ovo exhibited a progressive decline in the rate of growth and were hypocalcemic and hypoproteinemic compared to their in ovo counterparts from day 18 to day 26 of incubation. 2. The ratio of the concentrations of alpha-fetoprotein and albumin (AFP/A) in serum was determined for both groups of embryos. The AFP/A ratio may be useful as a biochemical index to stage avian embryonic development. Using this index it was concluded that ex ovo embryos exhibited a progressive developmental retardation compared to in ovo embryos. 3. Significant differences were observed in serum trace element concentrations for embryos incubated in ovo vs ex ovo. Most notably, serum copper concentration was significantly lower in ex ovo embryos on days 18 and 22 of incubation and significantly higher on day 26 of incubation compared to serum from embryos incubated in ovo. 4. Livers from embryos incubated ex ovo exhibited significant differences trace element levels compared to those incubated in ovo. By day 26 of incubation the concentration and total amount of zinc and iron were markedly elevated, whereas copper was greatly reduced in the livers of embryos incubated ex ovo compared to the corresponding in ovo levels. 5. Hearts from embryos incubated ex ovo contained less zinc and copper and more iron by day 26 of incubation than those from embryos incubated in ovo.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

The isolation and characterisation of hyaluronic acid in egg shell.

Analysis showed that the organic part of the chicken's egg shell consisted of a series of proteins and polysaccharides, probably present as glycoproteins and glycosaminoglycans. A purified preparation of a glycosaminoglycan (minimum mol. wt. 25 000), homogeneous by sedimentation velocity analysis and sedimentation to equilibrium in a density gradient, contained equimolar amounts of N-acetylglucosamine (36.3% s/w) and glucuronic acid 35.6% w/w). Digestion with testicular and streptomyces hyaluronidases and identification of the degradation products showed the glycosaminoglycan to be hyaluronidases and identification of the degradation products showed the glycosaminoglycan to be hyaluronic acid.

Acetylglucosamine↗
PubMed2006

Investigation on the adsorption capability of egg shell membrane towards model textile dyes.

Adsorption isotherms of Direct Red 80 (DR80) and Acid Blue 25 (AB25) on the egg shell membrane (ESM) were performed at 20+/-1 degrees C. Physical characteristics of ESM such as surface area and presence of functional groups were verified. The Fourier transform infra-red (FTIR) spectra proved the presence of functional groups such as hydroxyl, amine and carbonyl groups in ESM. The surface area of ESM was found to be 2.2098 m(2)/g. The effects of operational parameters such as initial dye concentration, pH(0), contact time, particle size and ESM doses were studied. The Langmuir, Freundlich, BET, Redlich-Peterson and Temkin adsorption models were applied to describe the equilibrium isotherms. The pseudo-first-order and pseudo-second-order kinetics models were examined to evaluate the kinetics data at different pH(0) values (2-12) and the rate constants were calculated. Maximum desorption of 81.8% was achieved for both dyes in aqueous solution at pH(0) 12. Also scanning electron micrographs (SEM) of the treated and untreated adsorbent were performed. Results indicate that ESM could be employed as a natural and Eco-Friendly adsorbent material for the removal of trace organics in solutions.

Adsorption↗
PubMed1999

Lysyl oxidase coupled with catalase in egg shell membrane.

The activity of lysyl oxidase was found in egg shell membrane (ESM) of hens. The activity was determined by measuring the enzymatic conversion of n-butylamine and Nalpha-acetyl-L-lysine to n-butyraldehyde and Nalpha-acetyl-L-allysine, respectively. ESM lysyl oxidase was significantly inhibited by beta-aminopropionitrile, chelating agents, and deoxygenation, consistent with the known properties of lysyl oxidase. Nevertheless, ESM lysyl oxidase was insoluble in urea solution, suggesting that it complexes with ESM. These findings support previous reports indicating the presence of lysine-derived cross-links in ESM and the necessity of lysyl oxidase located in the isthmus of the hen oviduct for the biosynthesis of ESM. Lysyl oxidase secreted around the egg white from the isthmus may initiate the cross-linking reaction of ESM protein, and remain as the constituent of ESM. Moreover, the H(2)O(2) released by lysyl oxidase in ESM was completely decomposed by coexisting catalase activity. ESM lysyl oxidase activity was greatly elevated in the presence of H(2)O(2), probably due to the O(2) produced by catalase. These findings indicate that lysyl oxidase is coupled with catalase in ESM. This coupling enzyme system was considered to be involved in the biosynthesis of ESM and to protect the embryo against H(2)O(2).

Animals↗
PubMed1998

Regulation of osteopontin gene expression during egg shell formation in the laying hen by mechanical strain.

The aim of this study is to evaluate the regulation of the osteopontin (OPN) gene expression by non-hormonal stimuli, such as calcium flux and mechanical strain during the daily egg cycle in the oviduct of the laying hen. After the egg enters the eggshell gland (ESG), the OPN gene is expressed by the epithelium cells in two waves: first by the basal cells and only then by the apical cells of the epithelium. A reduction in OPN gene expression was observed 1 h prior to laying. The calbindin gene, which marks the onset of calcification, was found to be expressed in the glandular epithelium starting 2 h after OPN gene expression. In addition, the formation of soft shells was accompanied by a reduction in calbindin, but not in OPN, gene expression. The application of a mechanical strain comparable to that induced by an egg led to induction of OPN gene expression at a normally quiescent phase in the cyclical expression of this gene. The induction of the gene was time- and strain-dependent and temporally similar to that induced by the entry of the egg into the ESG. In contrast, the calbindin gene was not affected by mechanical strain. The ESG of the laying hen provides a system to study the effect of a mechanical strain on matrix protein production in vivo, in a relevant physiological setting. The finding suggests that, in contrast to calbindin, OPN gene expression is not regulated by calcium flux but rather by the mechanical strain imposed by the resident egg.

Animals↗
PubMed1980

Egg-shell permeability and hatching of Ascaris suum.

When eggs of Ascaris suum were transferred from glass-distilled water into 0.1--0.4 M NaCl solutions, the water content of the unhatched juveniles fell with increasing concentration of solute. The effect was reversible. The egg-shell was thus permeable to water. The osmotic pressure of the egg fluid was osmotically equivalent to between 0.1 and 0.2 M trehalose. In hatching experiments in Fairbairn's medium containing 0.1 or 0.2 M trehalose, only 5 and 3% respectively of the eggs hatched; 83% of the eggs hatched in the absence of trehalose. The evidence suggests that loss of solutes from the egg fluid permits an increase in the water content of the unhatched juveniles and that this may be responsible for ending their quiescence.

Animals↗
PubMedDate not supplied

Purification and characterization of a vaterite-inducing peptide, pelovaterin, from the eggshells of Pelodiscus sinensis (Chinese soft-shelled turtle).

Proteins play a crucial role in the biomineralization of hard tissues such as eggshells. We report here the purification, characterization, and in vitro mineralization studies of a peptide, pelovaterin, extracted from eggshells of a soft-shelled turtle. It is a glycine-rich peptide with 42 amino acid residues and three disulfide bonds. When tested in vitro, the peptide induced the formation of a metastable vaterite phase. The floret-shaped morphology formed at a lower concentration ( approximately 1 microM) was transformed into spherical particles at higher concentrations (>500 microM). The solution properties of the peptide are investigated by circular dichroism (CD), fluorescence emission spectroscopy, and dynamic light scattering (DLS) experiments. The conformation of pelovaterin changed from an unordered state at a low concentration to a beta-sheet structure at high concentrations. Fluorescence emission studies indicated that the quantum yield is significantly decreased at higher concentrations, accompanied by a blue shift in the emission maximum. At higher concentrations a red-edge excitation shift was observed, indicating the restricted mobility of the peptide. On the basis of these observations, we discuss the presence of a peptide concentration-dependent monomer-multimer equilibrium in solution and its role in controlling the nucleation, growth, and morphology of CaCO(3) crystals. This is the first peptide known to induce the nucleation and stabilization of the vaterite phase in solution.

Amino Acid Sequence↗
PubMed2004

Palaeontology: pterosaur egg with a leathery shell.

The recent discovery of a pterosaur egg with embryonic skeleton and soft tissues from the Yixian Formation confirmed that the flying pterosaurs were oviparous. Here we describe another pterosaur egg whose exquisite preservation indicates that the shell structure was soft and leathery.

Animals↗
PubMed2002

Egg shell collagen formation in Caenorhabditis elegans involves a novel prolyl 4-hydroxylase expressed in spermatheca and embryos and possessing many unique properties.

The collagen prolyl 4-hydroxylases (EC ) play a critical role in the synthesis of all collagens. The enzymes from all vertebrate species studied are alpha(2)beta(2) tetramers, in which the beta subunit is identical to protein disulfide isomerase (PDI). Two isoforms of the catalytic alpha subunit, PHY-1 and PHY-2, have previously been characterized from Caenorhabditis elegans. We report here on the cloning and characterization of a third C. elegans alpha subunit isoform, PHY-3. It is much shorter than the previously characterized vertebrate and C. elegans alpha subunits and shows 23-30% amino acid sequence identity to PHY-1 and PHY-2 within the catalytic C-terminal region. Recombinant PHY-3 coexpressed in insect cells with a C. elegans PDI isoform that does not associate with PHY-1 was found to be an active prolyl 4-hydroxylase. The phy-3 gene consists of five exons, and its expression pattern differs distinctly from the hypodermally expressed phy-1 and phy-2 in that it is expressed in embryos, late larval stages, and adult nematodes, expression in the latter being restricted to the spermatheca. Nematodes homozygous for a phy-3 deletion are phenotypically of the wild type and fertile, but the 4-hydroxyproline content of phy-3(-/-) early embryos was reduced by about 90%. PHY-3 is thus likely to be involved in the synthesis of collagens in early embryos, probably of those in the egg shell.

Amino Acid Sequence↗
PubMed1999

Packaging effects on shell egg breakage rates during simulated transportation.

Shell eggs were packaged in either expanded polystyrene (EPS) foam or molded paper pulp (MPP) one dozen cartons, then were bulk packaged in either polypropylene crates or corrugated boxes. The packages were then subjected to a well-defined computer-simulated vibration test on an electrohydraulic test machine. The percentage and the location on the egg (side, top, bottom) of breakage was determined in the secondary (corrugated box or polypropylene crate) and primary (EPS or MPP carton) package after 15, 75, and 180 min. For each of three trials, 60 dozen Grade A large eggs were randomly assigned to each primary package and cross-stacked in a secondary container that contained three cartons in a row and a total of five layers. When cartons were packed in 15-dozen corrugated boxes, no significant difference was found in total eggshell damage rates between the MPP carton and the EPS carton. However, when eggs were packed in 15-dozen plastic crates, the MPP cartons caused significantly less eggshell damage than the EPS cartons. The EPS cartons packed in corrugated boxes had the lowest breakage (4.63%), whereas the EPS foam cartons packed in plastic crates had the highest breakage (12.59%). When the effect of secondary packaging and vibration time were not considered, no significant difference was found between MPP and EPS cartons. In addition, when the effect of primary packaging was not taken into account, the corrugated boxes had significantly lower breakage rates than the plastic crates. Nearly 55% of the breakage occurred in the bottom section of the eggshell as compared to the side and top. When the test periods were compared, the EPS cartons packed in plastic crates had the highest breakage (16.28%) at 180 min.

Animals↗
PubMed2001

Comparison of gonadal hormone levels in turkey embryos incubated in long-term shell-less culture and in ovo.

Changes in concentrations of 17beta-estradiol (E2) and androgenic hormones were measured in turkey embryos incubated in long-term, shell-less culture (ex ovo) and in ovo. Blood samples were obtained from both sets of embryos on Days 14, 16, 18, 20, and 22 and from embryos incubated in ovo on Days 24, 26, and 28. Ex ovo and in ovo embryos showed no differences in either hormone within sexes, with one exception. On Day 14 of incubation, the ex ovo females had higher (P < 0.05) E2 levels (55.6+/-5.1 pg/mL) than the in ovo females (32.2+/-2.3 pg/mL); however, this result might have been due to the small sample size (n = 3) for ex ovo females. No significant differences were found in androgen concentrations between sexes in ovo on Days 24, 26, and 28 of incubation. However, on Days 24, 26, and 28, in ovo females showed highly significant differences (P < 0.01) in E2 compared with males of the same age. These results indicate a similar developmental pattern for the endocrine system in ovo and ex ovo through Day 22 of incubation. Further, there were sex differences in E2 that are likely to be critical for sexual differentiation that emerges late in embryonic development.

Age Factors↗
PubMed2003

Presence of calcitonin receptors in shell gland of the guineafowl and changes in binding property during an oviposition cycle.

Radioligand binding assays of membrane fraction of the shell gland endometrium of guineafowl revealed the presence of receptor for calcitonin. The equilibrium dissociation constant (Kd) obtained by Scatchard analyses was 0.50 to 1.25 nM in laying birds and 1.12 to 1.19 nM in nonlaying birds. The maximum binding capacity (Bmax) per milligram of protein was 33.1 to 107.5 femtomoles in laying birds and 101.4 to 114.9 femtomoles in nonlaying birds. Both Kd and Bmax values changed during eggshell formation in laying birds. The results suggest that calcitonin receptor binding may be related to eggshell formation in guineafowl.

Animals↗
PubMed2004

Western immunoblotting in avian shell gland sample immunoblotting methods.

Avian shell gland tissue was subjected to Western blot analysis using anti-human estrogen receptor-alpha antibody H222. Initial attempts to obtain consistent, high-quality blots were unsuccessful because, as it turned out, excessive lipid in tissue preparations interfered with protein separation. Incremental additions of acetone eventually proved to be the critical step in solubilizing lipids and allowing consistent separation of bands on gels. A detailed description of the methodology is presented.

Animals↗