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At least 127 records · Page 7Linked to original sources

PubMed1991

Effects of selection for growth and selection diet on eggshell quality and embryonic development in Japanese quail.

Decreased hatchability in Japanese quail following selection for growth and relative improvements in hatchability following selection during goitrogen treatment were investigated. An unselected quail line (Line C) and lines selected for high 4-wk body weight while being fed diets containing either 20% CP and .2% thiouracil (TU) (Line T), or 28% CP and no TU (Lines P and H-CD) were used. Egg weight loss between 0 and 4, and 0 and 14 days of incubation, hatchability, and developmental stage of embryonic mortalities were determined in Experiment 1. Length of the incubation period, and percentages of body water and dry body weight were determined for 10- and 14-day embryos and 18-day-old chicks in Experiment 2. Eggshell quality was determined in Experiment 3. Hatchability was lower in selected than in unselected quail due to increased early and late embryonic mortality. Egg weight loss during incubation was greater in Line P than in Line C eggs. Weight loss, measured across lines, was lower in eggs that hatched than in those in which embryos died early. Percentage body water was higher in Line C than in Lines P and T at 14 and 18 days of incubation; however, percentage body water in Line T was lower than Line P at 14 days. Percentage of dry body weight was greater in Lines P and T than in Line C at 14 and 18 days. Eggshell thickness was greater in Line H-CD when compared with Line C. Increases in eggshell permeability occurring during selection for growth were associated with increased embryonic mortality and decreased hatchability.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Inheritance of tinted eggshell colors in white-shell stocks.

The present study was conducted to study the genetics of tinted eggshell colors in two breeds of chickens laying white-shell eggs. Reciprocal crosses were made between an inbred White Leghorn line (ES) and an inbred Ancona line (ANC). The F1 birds were intercrossed and F1 females were backcrossed to each of the original lines. Eggshell color from each resultant group was measured using a Minolta chromometer, and a value (e) representing the color intensity adjusted by hue and saturation was used as the measurement criterion. Age, hatch group, and crosses each contributed significantly to the variation seen in eggshell color. Distribution comparisons indicated that two major autosomal loci affected the trait in these lines: one gene having incomplete dominance controls the amount of pigment deposition; the second completely inhibits pigment deposition when homozygous recessive. A test of goodness of fit supported this hypothesis. Genetic components were estimated by linear models. Epistasis, dominance, and additive effects contributed significantly to this trait. No sex-linked effects were noted.

Analysis of Variance↗

PubMed1991

Collection and separation of Aedes taeniorhynchus eggshells from mangrove soil.

Two methods to separate eggshells of Aedes taeniorhynchus from mangrove soil were compared. Selective sieving, using nested sieves with 0.185 and 0.170-mm screen openings, and water flotation both removed over 99% of the soil. However, water flotation recovered a significantly greater percentage of eggshells (62% vs. 34%). There was no significant difference in the recovery rate of viable eggs and new and old eggshells using water flotation.

Aedes↗

PubMedDate not supplied

F strain Mycoplasma gallisepticum vaccination of post-production-peak commercial Leghorns and its effect on egg and eggshell quality.

Forty-five-week-old commercial leghorns negative for antibodies to Mycoplasma gallisepticum (MG) and M. synoviae were vaccinated with high-passage F strain MG (FMG). Hens were confined in modified Horsfall-Bauer isolation units through 60 weeks of age. Egg production (% hen day) and parameters of egg and eggshell quality were monitored, including egg weight, eggshell strength, Haugh unit score, pimpling, and blood/meat spot incidence. Egg production was significantly lower (P less than 0.05) for FMG vaccinates than controls (down 5.76% and 5.80% in Trials 1 and 2, respectively). However, vaccinates and controls did not differ significantly in eggshell strength, shell thickness, pimpling, or blood/meat spot incidence. Haugh unit scores were significantly (P less than 0.05) greater for FMG vaccinates. At necropsy, all reproductive tracts appeared grossly normal. These studies suggest that high-passage FMG vaccination of post-production-peak hens does not adversely affect oviduct function.

Animals↗

PubMed1983

Supplemented eggshell restores calcium transport in chorioallantoic membrane of cultured shell-less chick embryos.

It was previously reported (Tuan, 1980a) that the development-specific expression of calcium transport and related functions in the chick embryonic chorioallantoic membrane (CAM) requires the continuous presence of the eggshell, the calcium source of the embryo. To further understand the mechanism of action of the eggshell on the CAM functions, this study reports the effects of eggshell supplementation on chick embryos maintained in shell-less cultures. The cultured embryos were able to accumulate and utilize the exogenous shell calcium, applied directly onto the CAM, for skeletal formation. In the region of the CAM directly adhering to the added shell, calcium transport activity, calcium-binding protein (CaBP) activity, and vitamin K-dependent gamma-glutamyl carboxylase activity were significantly restored. These results strongly suggest that the proximity of shell calcium may regulate expression of calcium transport and related functions in the chick embryonic CAM.

Allantois↗

PubMed1997

Ultrastructure of the calcareous layer eggshell of the turtle Emys orbicularis (L.). Preliminary study.

The calcareous layer of Emys orbicularis eggshell was examined by scanning electron microscopy. The layer is composed of well distinguished shell units which consist of needle-like crystallites radiating outwards from the cores. The linear structures of the cores on the inner surface appear to be similar to those in the eggshell of Mauremys caspica. On the inner surface of shell units of eggs with dead embryos there are flat, conical depressions. This surface in specimens from unfertilized eggs is almost flat. It may suggest that a developing embryo derives calcium from the eggshell.

Animals↗

PubMed2025

Oocyte surface proteins EGG-1 and EGG-2 are required for eggshell integrity in Caenorhabditis elegans.

Metazoan eggs are surrounded by a specialized coat of extracellular matrix that mediates sperm-egg interactions. This coat is rapidly remodeled after fertilization to form a barrier that prevents polyspermy, protects against environmental insults, and provides structural support to the developing embryo. In C. elegans several oocyte surface proteins have been identified that mediate these events. However, whether two of these proteins, EGG-1 and EGG-2, are required for fertilization or downstream events has been unclear. Here, we address this question using more recent advances in genome editing tools through the creation of egg-1 egg-2 deletions of the endogenous loci. We found that egg-1 egg-2 oocytes are fertilization competent and form rudimentary eggshells. While the integrity of the egg-1 egg-2 eggshells are compromised and often rupture within the uterus, surprisingly, some embryos are capable of undergoing several rounds of cell division. Overall, our findings demonstrate that EGG-1 and EGG-2 are not required for fertilization but are involved in post-fertilization processes.

Caenorhabditis elegans↗

PubMed1975

Eggshell aspiration in infants.

Two infants inhaled eggshell fragments. The first aspirated a small fragment into the upper part of the trachea and resuscitation attempts resulted in descent of the foreign body to the right lower lobe bronchus. Two attempts at bronchoscopy were unsuccessful and spontaneous disintegration occurred. The second infant aspirated an eggshell fragment to the entrance of the larynx where it was removed by laryngoscopy. Laryngeal or tracheal foreign body in infants under 1 year of age are rare, and the diagnosis and removal are difficult.

Animals↗

PubMed1995

Onchocerca volvulus: identification and characterization of an immunogenic eggshell protein (Oveg1).

A major antigen recognized by human sera in Onchocerca volvulus infections is a parasite eggshell protein. The cDNA clone for this antigen was isolated from a lambda gt11 O. volvulus cDNA library using antisera from patients with high microfilarial counts. Sequence analysis of the cDNA clone predicts a polyglutamine repeat near the 5' end of the cDNA, and a motif of four arginines near the 3' end, reminiscent of that found in many regulatory proteins. The cDNA was subcloned into a yeast expression vector and reagent quantities of recombinant antigen produced in Saccharomyces cerevisiae. Antisera produced to the recombinant purified protein localized the antigen to the eggshell of developing microfilariae within the adult female uterus. No other sites of Oveg1 expression were noted in adult worms, but labeling was seen in internal membrane structures of L3 larvae. Sera from infected chimps recognized Oveg1 only after infections became patent. Sera from infected humans showed reactivity to Oveg1 that varied from 39 to 95%, depending upon the geographic location.

Amino Acid Sequence↗

PubMed1995

Purification and immunochemistry of a soluble matrix protein of the chicken eggshell (ovocleidin 17).

The protein components of biomineralized structures (matrix proteins) are believed to modulate crystal nucleation and growth, and thereby influence the shape and strength of the final structure. The chicken eggshell contains a complex array of distinct matrix proteins. The most abundant of these was purified to homogeneity by a combination of anionic exchange and hydroxyapatite chromatographies. Antibodies to this protein were raised in rabbit, and utilized for Western blotting and immunohistochemistry. These studies indicated that the 17 kDa antigen (ovocleidin 17, OC-17) is found in the shell gland mucosa, and that only the tubular gland cells were positive. Immunohistochemistry with decalcified shell indicated that OC-17 is uniformly distributed throughout the shell matrix, but concentrated in the mammillary bodies. Our results indicate that this protein is secreted during shell formation and becomes incorporated into this structure. It may therefore play a role in the crystallization process and influence the properties of the resulting eggshell.

Amino Acid Sequence↗

PubMed1993

Evolution of the dec-1 eggshell locus in Drosophila. II. Intraspecific DNA sequence analysis reveals length mutations in a repetitive region in D. melanogaster.

The dec-1 eggshell gene in Drosophila melanogaster encodes follicle cell proteins required for proper eggshell assembly. As shown by Southern and Northern analyses the dec-1 gene occurs in four alleles (Fc1-4) among wild-type strains. Its second exon has a distinct feature in the form of 12 repeats with 78-91 nucleotides; the first five show nearly 100% homology. DNA sequence comparison of the repeated region of the alleles revealed that the length polymorphisms are caused by changes in the numbers of the first five repeats. The results suggest that the alleles have been generated by unequal intragenic crossing-over and/or slippage during DNA replication and that the allelic length variants have arisen independently. The possibility that the most common allele, FC1, has a selective advantage over the other alleles is discussed.

Alleles↗

PubMed1978

Some observations on the calcium ion binding to the eggshell matrix.

The calcified matrix of the hen eggshell has been demineralized with the EDTA. Aliquots of this material are soluble in water and have been characterized by column chromatography and by chemical analyses. Of particular interest is the high hexosamine and uronic acid content, which confirms the protein-polysaccharide nature of this water-soluble material. The calcium ion binding to the eggshell matrix has been studied by the equilibrium dialysis technique at different pH values, with both free and blocked carboxylic groups. The material with the free carboxylic side chain groups binds more calcium ions with increasing pH value. When the carboxylic groups have been previously blocked with a water-soluble carbodiimide, the calcium ion binding rapidly decreases. The residual capacity to bind calcium ions in the material with the carboxylic functions modified is probably due to the sulfate ions. In agreement with previous observations on other calcified substrates, the calcium ion binding seems to depend on the presence of ionized carboxylic functions of the matrix.

Amino Acids↗

PubMed1990

Multiple proteins are produced from the dec-1 eggshell gene in Drosophila by alternative RNA splicing and proteolytic cleavage events.

The defective chorion-1 gene (dec-1) in Drosophila encodes follicle cell proteins necessary for proper eggshell assembly. A distinctive feature of the gene is the production of multiple products by both alternative RNA splicing and proteolytic processing events. DNA and protein sequencing studies have revealed several dec-1 protein products. The predominant translation product, fc106, has a vitelline membrane-like N-terminal domain followed by a glutamine, methionine-rich central region, largely in the form of 26 amino acid repeats. During late stage 10 the N-terminal portion of fc106 is cleaved, yielding s80, a major eggshell protein. Conceptual translation of the DNA sequence as well as molecular analyses of several dec-1 mutants suggest that the less abundant alternatively spliced RNAs encode primary translation products with different carboxy terminal ends. These results are discussed with respect to previous genetic analyses of dec-1 mutants as well as with respect to potential protein-protein interactions which may underlie stabilization of this complex extracellular structure.

Amino Acid Sequence↗

PubMed1986

Eggshell conductance--Fick's or Stefan's law?

The diffusion of gases through the avian eggshell has usually been interpreted as an example of Fick's law, and this appears to be the best explanation for gas exchange through narrow long pores. Many eggshells, however, contain more elaborate pores, of which the funnel-shaped type is the most common. It is suggested that most of the resistance to diffusion through these types of pores is best explained by Stefan's law of diffusion through apertures. The implications of this theory to the understanding of pore functions are discussed.

Animals↗

PubMed1988

Diffusive resistance of avian eggshell pores.

Resistance to gas diffusion through the avian eggshell resides in the microscopic pores which penetrate the shell. We calculated the resistance to water vapor diffusion of individual pores in the shells of 23 species of avian eggs, based on measurements of pore dimensions taken from drawings of 321 pore casts published by Tyler (1962, 1964, 1965) and Tyler and Simkiss (1959). Diffusive resistances were calculated from Fick's first law, using a 100-segment model of each pore. In addition, we added 2 series resistances, calculated from Stefan's law, to account for boundary layer resistances at the inner and outer pore apertures. Convective resistances for the same 100-segment model were computed from Poiseuille's law. A special, symmetrically branching model is presented for the diffusive resistance of the branched pores of ostrich eggshells, based on the drawings of Tyler and Simkiss (1959). The total aperture resistance was less than 6.2% of total pore resistance, while the outside aperture effect was on average only 1.5%. The calculated average pore conductance for all species was 5.4 micrograms (day Torr)-1, about three times higher than the average value of 1.6 micrograms (day Torr)-1 obtained by dividing measured shell conductance by the number of pores (Ar and Rahn, 1985). A possible explanation for this discrepancy is advanced. However, it is to be noted that in spite of the discrepancy, both calculated and functional values of pore conductance appear to be independent of egg mass.

Animals↗

PubMed1989

The relationship between eggshell porosity and air space gas tensions measured before and during the parafoetal period and their effects on the hatching process in the domestic fowl.

The partial pressure of gases in the air space were measured before and during the parafoetal period for domestic fowl eggs of the same initial weight but varying in eggshell conductance. Embryos developed and hatched normally from eggs with a wide range of shell conductance and resultant air space gas partial pressures. Air space PO2 levels measured just before pipping ranged from 55 to 65 mm Hg in low and high conductance eggs, respectively, whilst PCO2 levels ranged from 75 to 55 mm Hg. With increasing shell conductance embryos membrane-penetrated and pipped the shell later, but hatch time was unaffected. Membrane penetration and external pipping appeared to occur in response to the partial pressures of gas in the air space but not in response to one particular level of air space PO2 or PCO2. During the parafoetal stage air space PO2 decreased at about 3.8 mm Hg/h and air space PCO2 increased at about 1.8 mm Hg/h and these rates of change were unaffected by eggshell conductance.

Animals↗

PubMed1993

Oxygen and avian eggshell formation at high altitude.

Many birds at high altitude lay eggs with reduced eggshell diffusive conductance to water vapor. Disagreement exists about the cause, but hypotheses include physiological acclimatization and genetic adaptation. To investigate this, we tested for the occurrence of physiological acclimatization and quantified the effect of relieving hypoxia at high altitude. Ten laying hens (Gallus domesticus) were exposed to elevations of 3800 m (PIO2 90 Torr), 3800 m with supplementary oxygen (PIO2 140 Torr), and 1200 m (PIO2 125 Torr). 573 eggs were collected and analyzed during the 17-week experiment. Shell conductance, aggregate pore area, and shell thickness were reduced at 3800 m compared to 1200 m or 3800 m with supplementary oxygen. There was a lag in the response to changes in altitude or PIO2 that corresponded to a time constant of approximately 2.5 weeks. We conclude that physiological acclimatization of eggshell conductance occurs in some chickens, and that it is probably stimulated by hypoxia.

Acclimatization↗

PubMed1991

Three-dimensional reconstruction of innermost chorion layer of Drosophila grimshawi and Drosophila melanogaster eggshell mutant fs(1)384.

A low-resolution three-dimensional structure of the crystalline innermost chorionic layer (ICL) of the Hawaiian species Drosophila grimshawi and the Drosophila melanogaster eggshell mutant fs(1)384 has been calculated from electron microscope images of tilted negatively stained specimens. The isolated ICL of Drosophila grimshawi is a three-layer structure, about 36 nm thick, whereas the ICL of Drosophila melanogaster eggshell mutant fs(1)384 is a single layer, about 12 nm thick. Each unit in both crystalline structures includes octamers made up of four heterodimers. Crosslinks between the structural elements, both within and between unit cells form an interconnecting network, apparently important in maintaining the integrity of the layer. A model which may account for the ICL self-assembly formation in vivo and the ICL observed lattice polymorphism is proposed, combining data from the three-dimensional reconstruction work and secondary structure features of the ICL component proteins s36 and s38.

Animals↗