SEARCH · PubMed Health

Results for “eggshell”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources

PubMed1996

Differential activity of Ras1 during patterning of the Drosophila dorsoventral axis.

In Drosophila, the Ras1 gene is required downstream of receptor tyrosine kinases for correct eye development, embryonic patterning, wing vein formation, and border cell migration. Here we characterize a P-element allele of Ras1, Ras1(5703), that affects viability, eye morphogenesis, and early and late stages of oogenesis. Flies transheterozgyous for Ras1(5703) and existing EMS-induced Ras1 alleles are viable and exhibit a range of eye and eggshell defects. Differences in the severity of these phenotypes in different tissues suggest that there are allele-specific effects of Ras1 in development. Analysis of rescue constructs demonstrates that these differential phenotypes are due to loss of function in Ras1 alone and not due to effects on neighboring genes. Females mutant at the Ras1 locus lay eggs with reduced or missing dorsal eggshell structures. We observe dominant interactions between Ras1 mutants and other dorsoventral pathway mutants, including Egfr(top) and gurken. Ras1 is also epistatic to K10. Unlike Egfr(top) and gurken mutants, however, Ras1 females are moderately fertile, laying eggs with ventralized eggshells that can hatch normal larvae. These results suggest that Ras1 may have a different requirement in the patterning of the eggshell axis than in the patterning of the embryonic axis during oogenesis.

Alleles↗

PubMed2006

Role of egg buster in hatching of Aedes aegypti: scanning electron microscopy study.

Egg hatching has been studied in Aedes aegypti (L.) through scanning electron microscopy. The first sign of egg hatching is a small protrusion on the eggshell in the anterior pole. The larval movement provokes a crack in the eggshell with the egg buster located in the dorsal head. The egg buster provokes a small transverse fissure in the eggshell that gradually increases in the chorion. Then, the rupture is completed around the eggshell. The separation of the anterior pole occurs, showing the dorsal region of the larva head with the egg buster and the cap. After sequential movements, the larva looses the cap. Finally, the first instar is ready to be free showing details of its body with the egg buster over its head. This structure is a cuticular formation, similar to a cone structure that ends in a very fine tip and emerges from a pear-like depression with high rounded borders. Our results describe the anatomy of the egg hatching process in Ae. aegypti, showing details of the participation of the egg buster.

Aedes↗

PubMed2000

Effects of dietary fat type and level on broiler breeder performance.

The effects of added dietary fat type and level on broiler breeder performance were evaluated in two trials. In Trial 1, diets included no added fat (NAF) or 3.0% added poultry fat (PF) for individual bird energy intakes of 430 and 467 kcal/d at peak production (PCD), or 1.5% PF or 3.0% corn oil (CO) at 449 PCD. In Trial 2, diets contained NAF, 1.5 or 3.0% added CO or PF, or 3.0% lard (LA) for peak energy intakes of 463 PCD. All diets in Trial 2 were isocaloric and isonitrogenous. Feeding of experimental diets was initiated when breeders were 22 wk old in both trials, and hen BW was measured at various weeks between 22 and 47 wk in Trial 1 and between 27 and 65 wk in Trial 2. Egg production, egg weight (EW), eggshell quality, and hatchability were recorded at various weeks between 24 and 48 wk in Trial 1 and between 27 and 64 wk in Trial 2. Body weights and EW increased progressively, and eggshell quality fluctuated variably with age. Egg production peaked between Weeks 32 and 35, and hatchability was significantly depressed at Week 63. Egg weight and hatchability were not affected by dietary treatment; however, BW increased with energy level in the diet between Weeks 27 and 47. Body weight was also higher in birds fed 1.5 or 3.0% added fat compared with NAF and was higher in birds fed LA compared with CO at the 3.0% level. Egg specific gravity and shell weight per unit of surface area at Week 41 were increased by feeding low or high energy compared with moderate energy, and relative eggshell conductance was increased by using moderate compared with high energy diets and by feeding 1.5% PF compared with 3.0% PF. Egg specific gravity was increased by PF when compared with CO across fat level at Weeks 26 and 47 and by LA when compared with PF across fat level and breeder age. These data suggest that certain dietary energy and fat regimens may affect BW and eggshell quality without associated effects on EW and hatchability at various breeder ages.

Age Factors↗

PubMed2001

Breeder age influences embryogenesis in broiler hatching eggs.

The effects of dietary fat and broiler breeder age on egg and embryo characteristics during incubation were investigated. Breeders were fed diets containing no added fat or 3.0% added poultry fat (PF) for peak energy intakes of 430 and 467 kcal/hen day (pC/d), or 1.5% PF or 3.0% corn oil at 449 pC/d. Feeding of diets was initiated at 22 wk, and eggs were collected for incubation at 27 and 36 wk of age. Percentage incubational egg weight loss was determined between day of set and Days 6, 12, and 18. Percentage wet and dry embryo weights, embryo moisture content, and eggshell weights were determined at 6, 12, and 18 d of incubation. Percentage yolk sac weight and wet and dry liver weights and moisture content were determined on Days 12 and 18. Percentage gall bladder weight was determined on Day 18. There were no observed effects due to breeder diet. However, eggshell weight at Days 6, 12, and 18 was higher in 27-wk-old hens compared with 36-wk-old hens. Conversely, egg weight loss between Day 0 and Days 6, 12, and 18 and yolk sac weight across Days 12 and 18 of incubation were lower in eggs at 27 wk of age compared with 36 wk. At Day 18, dry embryo weight was higher and wet liver weight was lower at 27 wk compared with 36 wk. A slower rate of DM accumulation in embryos at Week 36 compared to Week 27 was associated with increased incubational water loss and decreased embryo moisture content, eggshell percentage, and yolk sac absorption rate. These data demonstrate that changes in eggshell characteristics with broiler breeder age can alone impact yolk uptake, growth, and body composition in subsequent embryos.

Age Factors↗

PubMed2003

Evaluation of a method of ultraviolet light sanitation of broiler hatching eggs.

Sanitation of hatching eggs is an important area of research due to the need for an effective, economical, and safe method of egg sanitation. Improved hatching egg sanitation is an important part of an overall pathogen reduction program within integrated poultry operations. This must be accomplished without disturbing the cuticle of the egg, which can decrease hatchability. The ability of ultraviolet (UV) light to kill bacteria on eggshell surfaces has been well documented. To accomplish the task of treating the eggs in a method that could be commercially implemented, a cabinet was constructed in which ultraviolet lamps were placed. A conveyor system was used to carry a plastic hatching egg flat containing 42 eggs through the cabinet for a period of 3 or 4 min. Ultraviolet intensities within the cabinet reached a maximum of 14 mW/cm2. Experiments were conducted to test the impact of UV light (254 nm) exposure of hatching eggs on aerobic plate counts (APC), inoculated Salmonella typhimurium and inoculated Escherchia coli. In the first three experiments, seven eggs were sampled from a flat passed through the UV chamber. Ultraviolet-treated eggs compared to untreated eggs had APC reductions of 1.3 log, S. typhimurium had a 4 log reduction, and E. coli had a 4 to 5 log reduction. Laboratory trials were also conducted to test the effects of UV irradiation on the cuticle of the egg and hatchability. No significant differences for eggshell conductance or hatchability were found between UV-treated and control eggs. From these trials, it can be concluded that UV irradiation of hatching eggs in a prototype irradiation cabinet can effectively reduce aerobic and pathogenic bacteria on eggshell surfaces without affecting eggshell conductance or hatchability.

Animals↗

PubMed2007

Effect of genotype on slaughtering performance and meat physical and sensory characteristics of organic laying hens.

Slaughtering yields and some meat physical and sensorial parameters of laying hens reared under organic system production were studied. The hens belonged to both Italian dual-purpose breeds [Ermellinata di Rovigo (ER; brown eggshell) and Robusta Maculata (RM; brown eggshell)] as well as hybrid genotypes [Hy Line White 36 (white eggshell) and Hy Line Brown (brown eggshell)]. The birds were reared under organic farming system production from 24 to 44 wk of age, when they were slaughtered. They were reared throughout summer and autumn, and the temperature ranged from about 28 to 3 degrees C. Local breeds presented higher (P < 0.01) live BW and dressing percentage compared with hybrids. The RM and ER carcasses had (P < 0.01) the highest breast and leg (thigh and drumstick) percentage, respectively. The muscle-bone ratio of the Hy Line White 36 drumstick was lower (P < 0.05) than the RM ratio, whereas the other groups were intermediate. The ER breast presented the highest (P < 0.01) lightness value and the lowest (P < 0.01) final pH value compared with the other 3 groups. The breast meat significantly differed according to genotype for almost all the studied sensorial parameters (adhesivity, fibrousness, chewiness, solubility, juiciness, tenderness, shear resistance), with the exception of aroma and odor intensity. In the thigh, genotype significantly affected aroma, adhesivity, fibrousness, solubility, tenderness, and shear resistance.

Abattoirs↗

PubMed1987

Regulation of 25-hydroxyvitamin D3 metabolism in chick embryo.

We investigated the time course of the development of renal 25-hydroxyvitamin D-1-hydroxylase and 25-hydroxyvitamin D-24-hydroxylase in chick embryos grown in the presence and absence of the eggshell. In embryos with the eggshell, the specific activity (SA) of 25-hydroxyvitamin D-1-hydroxylase in kidney homogenates increased from 0.68 fmol X min-1 X mg protein-1 at 12 days of gestation to a peak of 2.55 +/- 0.50 fmol X min-1 X mg-1 protein-1 at 17 days. In contrast, the SA of 25-hydroxyvitamin D-24-hydroxylase decreased from 2.5 fmol X min-1 X mg protein-1 to 0.90 +/- 0.25 fmol X min-1 X mg protein-1 during the interval. The total plasma calcium was significantly reduced in embryos without shells at 14 to 15 days of gestation (1.1 +/- 0.1 mM, mean +/- SE) compared with normal embryos of the same gestation (2.3 +/- 0.3 mM, P less than 0.002). In embryos without the eggshell, renal 25-hydroxyvitamin D-1-hydroxylase increased from 6.0 to 8.2 +/- 0.6 fmol X min-1 X mg protein-1 at 17 days of gestation and was from four- to sixfold higher than corresponding enzymatic activities for intact embryos. The increased enzyme activity resulting from loss of the eggshell was due to an increase in Vmax. The findings indicate that renal 25-hydroxyvitamin D-1-hydroxylase and 25-hydroxyvitamin D-24-hydroxylase in the chick embryo exhibit activity and show a large capacity for regulation in response to changes in calcium metabolism.

Animals↗

PubMed1995

Differential scanning calorimetry studies on the cysts of the potato-cyst nematode Globodera rostochiensis during freezing and melting

Differential scanning calorimetry (DSC) was used to determine the thermal events associated with freezing and melting of the cysts of the potato-cyst nematode Globodera rostochiensis. There were no thermal events during the cooling of dry cysts from 5 to -60 °C and warming back to 5 °C, indicating the absence of water freezing in the dry cysts. During heating of dry cysts from 5 to 80 °C, two overlapping endothermic events were observed at 55 °C, indicating the irreversible destruction of the permeability barrier of the eggshell by the melting of the lipids which constitute the lipid layer. The first exothermic event (T=-9 °C) during the cooling of hydrated cysts indicates the presence of an ice-nucleating agent. A broad exotherm at -38 °C is due to the freezing of eggs. DSC thus confirms that the eggshell prevents exogenous ice nucleation and allows the eggs to supercool in the presence of external ice. The enthalpy of the egg exotherm increased during hydration of the cysts. The temperature of the egg exotherm was elevated after heating of the sample to 70 °C. This is thought to be due to the loss of trehalose from the eggs following the destruction of the permeability barrier of the eggshell. During melting, three endothermic events were observed. These became merged after the destruction of the permeability barrier of the eggshell by heating, and only two peaks were observed in isolated eggs. The sample is thus considered to consist of three freezable compartments: (1) the water surrounding the cyst, (2) the solution between the cyst wall and the eggs and (3) the egg contents.

Journal Article↗

PubMed1985

Magnesium, calcium, and phosphorus content of shells from hatching and nonhatching turkey eggs.

Shells of hatching and nonhatching Large White turkey eggs were examined for magnesium, calcium, and phosphorus content. Eggshells containing embryos that hatched contained significantly (P less than .05) more magnesium than shells from nonhatching eggs. No differences were seen in their calcium content. Eggshells from pipped eggs contained significantly (P less than .05) more phosphorus than shells from eggs that were not pipped or those that hatched. Calcium and magnesium in turkey eggshells declined as time in lay increased. Injections of exogenous magnesium both at setting and transfer significantly (P less than .05) depressed hatchability, whereas exogenous calcium injected at transfer significantly (P less than .05) improved hatchability. Injections of exogenous calcium at the time of setting significantly (P less than .05) depressed hatchability. It was concluded that the mineral content of turkey eggshells may influence embryo physiology and hatchability.

Animals↗

PubMed1987

Water balance in incubating turkey eggs.

The eggshell water vapor conductance capable of maintaining constant water content in incubating turkey eggs was determined for three different egg weight classifications. Metabolism of the developing turkey embryos was altered by increasing or decreasing eggshell permeability. Eggshell permeability accommodated metabolic water in large eggs very well. Both relative poult weights and relative water content of embryos in large eggs at the plateau stage in oxygen consumption decreased or increased allometrically to the permeability treatment. However, among small and medium eggs, if eggshell permeability was increased, relative poult weights at hatching were much less than expected. This occurred despite the fact that relative water content of the eggs at 25 days of incubation was not similarly affected. The data suggest a biological asynchrony for egg size, metabolism, and water content of turkey eggs.

Animals↗

PubMed1991

Hydrogen peroxide as an alternative hatching egg disinfectant.

The present study examined the effectiveness of H2O2 at different concentrations to disinfect broiler hatching eggshell surfaces and to maintain hatching potential. Under pure culture conditions, .50% H2O2 yielded over a 6 log kill in 30 s of three potential eggshell bacterial contaminants. Under higher H2O2 demands, such as occurs on eggshell surfaces, H2O2 concentrations of 5% (vol/vol) were required to disinfect the shell surfaces (approximately 5 log reduction). Hatchability of fertile eggs from a 44-wk-old flock was significantly increased by 2% following spraying 5% H2O2 in comparison to untreated controls. Level of contaminated eggs and "early-dead" embryos were significantly reduced in the H2O2-treated eggs. In comparison with formaldehyde fumigation, no significant difference in hatchability due to H2O2 treatment was detected in eggs from a 30- or 56-wk-old flock. Eggshell permeability, as measured by egg moisture loss in an incubator, was not significantly affected by H2O2 (5%) or formaldehyde fumigation when compared with untreated or water-sprayed control eggs. These results demonstrated that H2O2 compared favorably to formaldehyde as a hatching egg disinfectant without adversely affecting hatching potential. Under some conditions, H2O2 actually improved the hatching potential of fertile broiler eggs compared with hatchability of untreated eggs.

Animals↗

PubMed1994

Hatchery-acquired salmonellae in broiler chicks.

Hatchery contamination can result in exposure of newly hatched chicks to salmonellae at a time when they are most susceptible to colonization of their intestinal tract. Eggshell fragments, external rinses, and intestinal tracts from day-of-hatch chicks were sampled for salmonellae contamination. Chicks from the same hatching trays were then put in isolators or floor pens and fed a pelleted corn-soybean ration for 1 wk before external rinses and ceca from each chick were sampled for salmonellae. About 17% of eggshell, 21% of chick rinses, and 5% of intestines sampled at Day 0 were positive for salmonellae. No differences were observed between broiler hatcheries, but significant differences were seen between replications within hatching cabinets. Results from this study suggest a correlation between hatchery-acquired salmonellae and the production of potential seeder birds. No differences between eggshell and chick rinse samples were found (correlation = .81); therefore, eggshells are recommended as the best sample to determine hatchery salmonellae contamination.

Air Microbiology↗

PubMedDate not supplied

Presence and recovery of Ascaridia dissimilis ova on the external shell surface of turkey eggs.

Ascaridia dissimilis, a roundworm in turkeys, has been noted with increased frequency in commercial turkeys. Because infected turkeys can shed A. dissimilis ova in their feces, the potential exists for the external surface of turkey eggshells to be contaminated with A. dissimilis ova. The objectives of this study were to determine the presence of and recover A. dissimilis ova on the external surface of the turkey egg. In Experiment 1, turkey eggs were collected from naturally infected flocks, and eggs were processed by a sodium hydroxide procedure to recover any A. dissimilis ova on the external egg surface. In Experiment 2, the external surface of the turkey eggs was inoculated with 116 A. dissimilis ova/g feces, and eggshells were sampled every 3 days until 28 days of incubation to assess the recovery of A. dissimilis ova from the eggshell. In Experiment 1, of the 36 eggs examined from a flock naturally infected with A. dissimilis, one egg had an A. dissimilis ovum on its external eggshell surface. Experiment 2 demonstrated that A. dissimilis ova can be recovered from the external egg surface after a 28-day incubation period in the incubator. Ova recovery declined from an average of 62 A. dissimilis ova/turkey egg at day 2 of incubation to an average of 3 A. dissimilis ova/turkey egg at day 28 of incubation.

Animals↗

PubMed2002

Eggs of the stink bug Acrosternum (Chinavia) marginatum (Hemiptera: Pentatomidae): a scanning electron microscopy study.

The morphology of the outer face of the eggshell, its appearance in cross fractures and the surface morphology of the inner face are described in the green stink bug Acrosternum (Chinavia) marginatum (Hemiptera: Pentatomidae) using scanning electron microscopy. Deposited eggs are barrel-shaped and the surface consists of hexagonally arranged, funnel-shaped pits that possess transverse diaphragms in their slender, basal portions. Only minor differences are detectable between the central portion of the anterior plate (the operculum) and the lateral wall together with the basal portion of the eggshell. The rim at the anterior pole of the egg carries processes with a bulbous end, the aero-micropylar processes. A narrow band of the anterior plate bordering these processes shows hexagonally arranged elements. These differ from those of the operculum and the lateral wall, in that cylindrical pits are abundant. During hatching, the operculum is lifted precisely at the rim of this area. Inspection of the periphery of the inner face of the operculum reveals slender, radially arranged grooves. Their arrangement and spacing indicate that they bear a spatial relationship with the aero-micropylar processes. Their role may lie in guiding the sperm to the site where fertilization occurs and in facilitating the gas exchange of the embryo. The remainder of the eggshell carries shallow elevations at its inner face. Exterior and interior features of the eggshell, as well as its appearance in cross-fractures, are discussed.

Animals↗

PubMed2006

[In situ resonance Raman spectra of organic pigments in freshwater cultured pearls].

In situ resonance Raman spectra of Chinese freshwater pearls were collected and analysed systematically with three different excitation wavelengths at lambda = 514, 633 and 785 nm. At the same time, the Raman spectra of eggshells of Pomacea canaliculata were also collected under the same experimental conditions in order to compare with pearls' Raman spectra. The conclusions were as follows: (1) Frequency dispersions of Raman spectra of organic pigments were obviously observed in Raman spectra of pearls. In contrast, Raman spectra of organic pigments in eggshells of Pomacea canaliculata showed no frequency dispersion phenomena; (2) It was considered that the organic pigments in pearls were polyacetylenic materials but not carotenoids which was proposed by previous researchers, and the organic pigments in eggshells of Pomacea canaliculata were carotenoids; (3) The conjugated (>=C number of polyacetylenic material in pearls was calculated to be about 10 and 16, and the conjugated C[double bond]C number of carotenoid in eggshells of Pomacea canaliculata was about 13 based on the Raman shifts caused by conjugated C[double bond]C double bonds.

Animals↗

PubMed2000

Uterine morphology during the annual cycle in Chalcides ocellatus tiligugu (Gmelin) (Squamata: scincidae).

The uterus of the viviparous skink Chalcides ocellatus tiligugu was studied by SEM and LM during the annual cycle. Three functional phases were identified: preovulatory (spring), gestatory (summer), and quiescent (autumn-winter), characterized by changes in the uterine wall (mainly the endometrial layer). In the preovulatory phase, the uterine wall increases in thickness; its luminal epithelium has ciliated cells and two types of unciliated secretory cells. The first type secretes sulfated glycosaminoglycans (GAGs), which form the amorphous inner layer of the eggshell membrane; the second type secretes acidic glycoproteins that form the intrafibrillar matrix of the outer layer of the eggshell membrane. The lamina propria contains simple alveolar glands that secrete the collagen fibers of the eggshell membrane. During the gestatory phase, the glycoproteins produced by secretory cells of the second type have histotrophic activity for the developing embryo. The uterus widens to form incubation chambers with two hemispheres, one embryonic and the other abembryonic. Both a chorioallantoic placenta and an omphaloplacenta with histotrophic activity are present in late gestation. The chorioallantoic placenta, with aspects of a Weekes (1935) Type III placenta, develops in the embryonic hemisphere. The omphaloplacenta forms at the vegetative pole of the egg and shows cellular hypertrophy of the bilaminar omphalopleure and uterus. During the quiescent phase, the uterus gradually decreases in thickness and activity; its luminal epithelium does not show secretory activity. The annual variations in the myometrial layer involved the inner circular and the outer longitudinal muscle layers.

Animals↗

PubMed2002

Effects of posture on the respiratory mechanics of the chick embryo.

In the chicken embryo, pulmonary ventilation and pulmonary gas exchange begin approximately one day before the completion of hatching. We asked to what extent the posture inside the egg, and the presence of the eggshell and membranes, may alter the mechanical behaviour of the respiratory system. The passive mechanical properties of the respiratory system were studied in chicken embryos during the internal pipping phase (rupture of the air cell) or the external pipping phase (hole in the eggshell). Tracheal pressure and changes in lung volume were recorded during mechanical ventilation, first, with the embryo curled up inside the egg, then again after exteriorization from the eggshell. In the internal pippers, respiratory system compliance increased and expiratory resistance decreased after exteriorization, whereas the mean inspiratory impedance did not change. In the external pippers, exteriorization had no significant effects on respiratory compliance, resistance, or impedance, and the values were similar to those of newly hatched chicks. We conclude that, in the chicken embryo, at a time when pulmonary ventilation becomes an important mechanism for gas exchange, the curled up posture inside the egg does not provide any significant mechanical constraint to breathing.

Aging↗

PubMed2006

Evolutionary genetics of vertebrate tissue mineralization: the origin and evolution of the secretory calcium-binding phosphoprotein family.

Three principal mineralized tissues are present in teeth; a highly mineralized surface layer (enamel or enameloid), body dentin, and basal bone. Similar tissues have been identified in the dermal skeleton of Paleozoic jawless vertebrates, suggesting their ancient origin. These dental tissues form on protein matrix and their mineralization is controlled by distinctive proteins. We have shown that many secretory calcium-binding phosphoproteins (SCPPs) are involved in tetrapod tissue mineralization. These SCPPs all originated from the common ancestral gene SPARCL1 (secreted protein, acidic, cysteine-rich like 1) that initially arose from SPARC. The SCPP family also includes a bird eggshell matrix protein, mammalian milk casein, and salivary proteins. The eggshell SCPP plays crucial roles in rigid eggshell production, milk SCPPs in efficient lactation and in the evolution of complex dentition, and salivary SCPPs in maintaining tooth integrity. A comparative analysis of the mammalian, avian, and amphibian genomes revealed a tandem duplication history of the SCPP genes in tetrapods. Although these tetrapod SCPP genes are fewer in teleost genomes, independent parallel duplication has created distinct SCPP genes in this lineage. These teleost SCPPs are also used for enameloid and dentin mineralization, implying essential roles of SCPPs for dental tissue mineralization in osteichthyans. However, the SCPPs used for tetrapod enamel and teleost enameloid, as well as tetrapod dentin and teleost dentin, are all different. Thus, the evolution of vertebrate mineralized tissues seems to be explained by phenogenetic drift: while mineralized tissues are retained during vertebrate evolution, the underlying genetic basis has extensively drifted.

Animals↗