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PubMed1992

Mammalian sperm-egg fusion: the rat egg has complementary sites for a sperm protein that mediates gamete fusion.

Rat epididymal protein DE is localized on the fusogenic region of the acrosome-reacted spermatozoa and has a potential role in sperm-egg fusion. We investigated the presence of DE binding sites on the egg surface by co-incubating zona-free eggs and capacitated sperm in different concentrations of pure DE. Results indicate that DE produced a concentration-dependent decrease in egg penetration by sperm (fusion), with almost complete inhibition at 200 micrograms/ml. This inhibition was not due to an effect of DE on initial sperm binding to the egg membrane, since the presence of this protein did not affect the percentage of oocytes with bound sperm nor the number of bound sperm per egg. Those sperm that failed to penetrate the egg in the presence of DE became able to do so after transfer of the eggs to protein- and sperm-free medium, indicating a role for DE in an event subsequent to binding and leading to fusion. Indirect immunofluorescence using a polyclonal antibody against DE revealed a patchy labeling over the entire egg surface, with the exception of the area overlying the second metaphase spindle. This conclusion was supported by the disappearance of the DE-negative area on the fertilized egg. Zona-free eggs, incubated with DE at 4 degrees C or fixed before exposure to DE, displayed a uniform staining, suggesting that the patchy labeling resulted from aggregation of DE binding sites by the purified protein. The aggregation of these egg components may represent a necessary step of the fusion process. To our knowledge, this is the first study reporting the existence and localization of complementary sites to a specific sperm protein on the plasma membrane of the mammalian egg.

Amino Acid Sequence↗
PubMedDate not supplied

Water balance, growth, development, and survival of arboreal frog eggs (Chirixalus eiffingeri, Rhacophoridae): importance of egg distribution in bamboo stumps.

We studied the effects of substrate moisture and flooding on the arboreal eggs of Chirixalus eiffingeri and determined the possible causes of egg mortality. Eggs appear highly permeable to water vapor, losing 16.24% and 38.38% of initial egg mass in 2 h at 90% and 45% relative humidity, respectively. Eggs that experienced positive water uptake developed faster, hatched earlier with larger hatchlings, and had greater hatching success than eggs that experienced negligible or negative water uptake. The hatching success of eggs that were submerged in water in bamboo stumps was significantly lower than that of eggs that were incubated on the water surface and was significantly correlated with the water PO2. In some bamboo stumps, we observed chironomid and tipulid larvae preying on submerged eggs. A dilution of water collected from bamboo stumps did not increase the hatching success of eggs. The water PO2 of bamboo stumps in the field was 67.4+/-18.8 mmHg, and the degree of hypoxia of water in each bamboo stump was correlated with the turbidity. Our findings demonstrated that the vertical distribution of C. eiffingeri eggs on walls of bamboo stumps significantly influenced the growth, development, and survival of embryos. Eggs deposited too far from the water may become desiccated, while eggs deposited too close to the water may become submerged and die of hypoxia or predation by insect larvae.

Adaptation, Physiological↗
PubMed2004

Maternal effects of egg size on emu Dromaius novaehollandiae egg composition and hatchling phenotype.

Parental investment in eggs and, consequently, in offspring can profoundly influence the phenotype, survival and ultimately evolutionary fitness of an organism. Avian eggs are excellent model systems to examine maternal allocation of energy translated through egg size variation. We used the natural range in emu Dromaius novaehollandiae egg size, from 400 g to >700 g, to examine the influence of maternal investment in eggs on the morphology and physiology of hatchlings. Female emus provisioned larger eggs with a greater absolute amount of energy, nutrients and water in the yolk and albumen. Variation in maternal investment was reflected in differences in hatchling size, which increased isometrically with egg size. Egg size also influenced the physiology of developing emu embryos, such that late-term embryonic metabolic rate was positively correlated with egg size and embryos developing in larger eggs consumed more yolk during development. Large eggs produced hatchlings that were both heavier (yolk-free wet and dry mass) and structurally larger (tibiotarsus and culmen lengths) than hatchlings emerging from smaller eggs. As with many other precocial birds, larger hatchlings also contained more water, which was reflected in a greater blood volume. However, blood osmolality, hemoglobin content and hematocrit did not vary with hatchling mass. Emu maternal investment in offspring, measured by egg size and composition, is significantly correlated with the morphology and physiology of hatchlings and, in turn, may influence the success of these organisms during the first days of the juvenile stage.

Animals↗
PubMed2000

Maternal energy investment in eggs and jelly coats surrounding eggs of the echinoid Arbacia punctulata.

In free-spawning marine invertebrates, the amount of maternal energy that is invested in each egg has profound implications for all life-history stages of the offspring. The eggs of echinoids are freely spawned into the water and are surrounded by several structurally complex extracellular layers. These extracellular layers, or jelly coats, do not contribute energy to embryonic development but must impose an energy cost on the production of each egg. The investment of maternal energy reserves in the jelly coats of echinoid eggs may have important implications for the number of eggs that can be produced (i.e., fecundity) and the amount of energy that can be invested in each egg. We estimated the degree to which maternal energy is invested in the jelly coats surrounding eggs of the echinoid Arbacia punctulata. Estimates were derived from measurements of the amount of energy contained in the combined eggs and jelly coats, and in the eggs alone. The amount of energy contained in A. punctulata eggs ranged from 2.70 to 5.53 x 10(-4) J egg(-1). The amount of energy contained in the jelly coats ranged from 0.13 to 0.48 x 10(-4) J jelly coat(-1). The mean concentration of energy in the eggs was 2.15 mm(-3) and 0.29 J mm(-3) in the jelly coats. These results indicate that between 3% and 11% (mean = 7%) of the total energy invested in each A. punctulata egg is partitioned to the jelly coat alone. A significant positive relationship was found between the volumes of the jelly coats and the amount of energy they contained. Based on this relationship and an analysis of differences in the size of jelly coats between echinoid species, we suggest that the degree to which energy is invested in jelly coats may vary among echinoid species and is therefore likely to be an important life-history characteristic of these organisms.

Animals↗
PubMed1988

Bird-egg syndrome. Cross-reactivity between bird antigens and egg-yolk livetins in IgE-mediated hypersensitivity.

87 adult patients from our allergy clinic were skin tested with budgerigar and canary feathers, hen's egg white and egg yolk and common inhalant allergens. Of 59 patients found to be atopic, 17 (29%) were concomitantly sensitized to bird dander and egg proteins, 10 of them being symptomatic to bird dander and/or egg exposure. All but 1 of the egg-symptomatic patients were exposed to pet birds. The patients with strong serological reactivity to bird antigens were also exclusively sensitized to egg proteins, in particular to livetins (water-soluble fractions of egg-yolk proteins). Extensive RAST-inhibition studies demonstrated identical patterns of cross-reactivity between bird dander and hen's egg proteins, livetins being the major cross-reacting antigens. This peculiar IgE-mediated allergy is designated as 'bird-egg syndrome'. It is suggested that egg intolerance in adults is mainly due to sensitization to egg-yolk livetins and can be provoked by inhalation of pet bird dander. Thus, it must be distinguished from the common egg-white allergy of atopic children. Our study further underlines the importance of respiratory sensitization in adult food allergy. On the other hand, exposure to cross-reacting antigens by ingestion might also influence the allergic manifestations to inhalant allergens.

Adult↗
PubMed2002

Fatty acid composition and egg components of specialty eggs.

Egg components, total fat, and fatty acid content of specialty eggs were compared. One dozen eggs were collected and analyzed from each of five different brands from hens fed a diet free of animal fat (SP1), certified organic free-range brown eggs (SP2), uncaged unmedicated brown eggs (SP3), cage-free vegetarian diet brown eggs (SP4), or naturally nested uncaged (SP5). Regular white-shelled eggs were the control. A significant (P < 0.05) difference was observed in the egg components and fatty acid content in different brands. The percentage of yolk was lower (P < 0.05) in SP2 and SP4 with a concomitant increase (P < 0.05) in the percentage of white. The percentage of shell was lower (P < 0.05) in SP4 and SP5. The total edible portion was greater in SP4 and SP5. The yolk:white ratio was greater (P < 0.05) in SP3. The total lipid content was lower in SP4 eggs. The content of palmitic (C16:0), stearic (C18:0), and total saturated fatty acids were lower (P < 0.05) in SP1. No difference was observed in the content of palmitoleic (C16:1), oleic (C18:1), or total monounsaturated fatty acids. The content of n-3 fatty acids in SP2, SP4, and SP5 were similar to control eggs. The ratio of total n-6:n-3 polyunsaturated fatty acids ranged from 39.2 for SP5 to 11.5 for SP1 (P < 0.05). No difference was observed in the total polyunsaturated fatty acid content of eggs (P > 0.05).

Animal Feed↗
PubMed1994

Allergenicity and antigenicity of chicken egg ovomucoid (Gal d III) compared with ovalbumin (Gal d I) in children with egg allergy and in mice.

When attempting to generate mouse monoclonal antibodies to hen's egg ovalbumin, injection of commercially purified ovalbumin resulted in monoclonal antibodies, which when assayed against commercially purified ovalbumin (Gal d I) or ovomucoid (Gal d III), appeared to be specific to both. With the use of high-performance liquid chromatography (HPLC)-repurified ovalbumin and ovomucoid in assay procedures, monoclonal antibodies generated by commercially purified ovalbumin were found to be specific for ovomucoid only. To clarify this phenomenon, mice were serially injected with commercially purified ovalbumin or HPLC-repurified ovalbumin. It was found that most of the antibody response to commercially purified ovalbumin was directed against the minor (< 1%) ovomucoid contaminant and that HPLC-repurified ovalbumin failed to produce antibodies to ovomucoid. Commercially purified ovomucoid resulted in only minimal amounts of antibodies to ovalbumin. Thus when commercially purified ovalbumin is used both for immunization and immunoassay, most of the antibodies produced are actually against the small amount of ovomucoid contaminant, and not ovalbumin. To determine whether ovomucoid is the major antigenic and allergenic egg white protein in human beings, one group of 18 children with egg allergy were skin prick tested with half-log dilutions of egg white extract and diethylaminoethyl cellulose (DEAE)-repurified ovomucoid, ovalbumin, and lysozyme. Ovomucoid mean wheal diameters were significantly greater than wheal diameters in response to ovalbumin, lysozyme, and egg white extract at the three most concentrated of five dilutions tested: 0.01, 0.03, and 0.1 mg/ml (p < 0.01). Serum ovomucoid-specific IgE and IgG antibody concentrations to DEAE-repurified ovomucoid were significantly greater than that to DEAE-repurified ovalbumin (p < 0.05). In a second study, 10 patients with egg allergy and persistent egg hypersensitivity were compared with 11 patients with egg allergy in whom clinical tolerance to egg developed. IgE antibodies to repurified ovomucoid were significantly greater in patients with persistent egg hypersensitivity compared with patients in whom clinical tolerance developed at the time of both initial and follow-up food challenges. In contrast, there were no significant differences in IgE antibody concentrations to repurified ovalbumin in either group at any time. These results suggest that ovomucoid is the immunodominant protein fraction in egg white and that the use of commercially purified ovalbumin has led to an overestimation of the dominance of ovalbumin as a major egg allergen and antigen in human beings.

Adolescent↗
PubMed2004

Oxidative stability of silky fowl eggs. Comparison with hen eggs.

Oxidative stability of original silky fowl's eggs was investigated. The silky fowl's whole eggs indicated significant oxidative stability compared to hen's eggs in storage for 14 days. The hen eggs showed an increased amount of hydroperoxides on 6 days of storage at room temperature. In contrast, the silky fowl eggs showed restricted generation of hydroperoxides until 8 days and then a gradual increase. Though pigment extracted with chloroform/methanol (2:1) solvent from hen's whole egg turned brown for 14 days, the pigment extracted from silky fowl's whole egg slowly turned brown. Unsaturated fatty acids in silky fowl eggs were 62.5% among total fatty acids, while the unsaturated fatty acids of hen's eggs were 53.9%. It is speculated that the silky fowl eggs show oxidative stability owing to the higher ratio of unsaturated fatty acids in the silky fowl eggs compared with that of hen eggs.

Animals↗
PubMed1998

Inhalant allergy to egg yolk and egg white proteins.

BACKGROUND: Several egg white and egg yolk and avian proteins have been described as a cause of inhalant allergy. Sometimes inhalational type I hypersensitivity to these proteins is associated with food allergy to egg. OBJECTIVE: We studied two patients who experienced respiratory and food allergic symptoms upon exposure to egg or avian antigens through the inhalative or digestive routes. Clinical and immunological studies were carried out in order to identify individual allergens from these sources that could be responsible for crossreactivity reactions. RESULTS: Patient 1 showed IgE sensitization to egg yolk livetins, feathers, and chicken serum. Specific bronchial challenge with chicken albumin and livetin extracts elicited a positive early asthmatic response and an increase in serum eosinophil cationic protein. Immunoblot and CAP-inhibition studies in this patient supported that chicken albumin (alpha-livetin) was the crossreactive antigen present in egg yolk and chicken serum and feathers. Patient 2 showed sensitization to egg white, ovomucoid and lysozyme. However, SDS-PAGE and immunoblot studies demonstrated contaminating lysozyme in the ovomucoid extract and identified lysozyme as the main allergen causing egg sensitization in this patient. Conjunctival challenge test confirmed allergy to lysozyme. CONCLUSION: Egg yolk and egg white proteins may act not only as ingested allergens but also as aeroallergens. Immunological studies using highly purified preparations of egg proteins are useful for the accurate diagnosis of allergic reactions to egg proteins and to identify individual allergens that may be responsible for crossreactivity reactions.

Adult↗
PubMed2001

Examining the effects of prestorage incubation of turkey breeder eggs on embryonic development and hatchability of eggs stored for four or fourteen days.

Thirty-six hundred British United Turkey hatching eggs were used in two separate trials to test whether prestorage incubation (PRESI) treatments of 0, 6, and 12 h (Trial 1) or 0, 7, and 14 h (Trial 2) could improve the hatchability of eggs stored (17 C) for 14 versus 4 d. The development of the embryos (n = 30) was staged before and after exposing eggs to the various PRESI treatments. Embryonic development was also established after storage to ascertain whether embryonic development was occurring during storage. The remaining eggs in each trial were split into three groups (n = 500) and incubated for 28 d to examine embryonic mortality and hatchability. No changes were observed in embryonic development due to egg storage. Embryos were significantly more developed as the number of PRESI h increased; therefore, embryos from different PRESI treatments were placed in storage at different stages of development. Early mortality (1 to 7 d of incubation), mortality at internal and external pipping, and hatchability of fertile eggs were significantly reduced in eggs stored for 14 versus 4 d. The various PRESI treatments did not significantly affect the mortality or hatchability of eggs stored for 4 d. However, the hatchability of eggs incubated prior to storage for 12 h and then stored for 14 d was restored to the levels reported for eggs subjected to the treatment that represents the industry norm (0 h of PRESI and 4 d storage). These results indicate that embryos of eggs stored for 14 d, which have developmentally advanced to the stage of complete hypoblast formation (PRESI for 12 h), have a survival advantage over eggs stored for 14 d that have not been subjected to any PRESI.

Animals↗
PubMed2005

Melengestrol acetate as an effective alternative to induce a decline in egg production and reversible regression of the reproductive tract in laying hens. II. Effects on postmolt egg quality.

Induced molting increases egg quality and egg production and extends the productive life of hens. Molting is accomplished by feed withdrawal, which has received criticism, and alternatives described thus far result in poor postmolt performance. Melengestrol acetate at a dosage of 4 or 8 mg/d, in a balanced diet, leads to reversible regression of the reproductive tract. However, this alternative must also increase egg quality after rest to be considered an adequate method by the industry. Hy-Line W-36 (n = 497) laying hens were assigned randomly to a diet containing 0 mg of melengestrol acetate (MGA; control) throughout the experiment or 4 or 8 mg of MGA/d for 2, 4, or 6 wk. Upon reaching 50 and 70% lay, after MGA removal, eggs were collected for measurements of egg quality, including Haugh units (i.e., internal egg quality), shell thickness, and breaking strength (i.e., external egg quality). Haugh units were greater (P < 0.05) for eggs laid by hens molted with a diet containing 8 mg of MGA for all durations compared with controls. Shell thickness was greater (P < 0.05) when hens were treated with 4 mg of MGA for 6 wk and 8 mg of MGA for 4 and 6 wk compared with control. Egg breaking strength was greater (P < 0.05) than controls for all hens fed MGA, regardless of dosage or duration of feeding. A subset of hens was fed 8 mg of MGA per hen/d for 2 wk, and eggs were collected for 3 wk. Seven days after MGA was removed from the diet, the amount of MGA in the yolk was below the level of detection of the assay, and the concentration found in the eggs at all time points was 3 orders of magnitude below the Food and Drug Administration's tolerance for MGA in edible tissue. When used as an alterative method to induce a rest, MGA leads to an increase in the internal and external egg quality of hens compared with nonmolted hens.

Aging↗
PubMed2004

Prevalence of high-risk egg-preparation practices in restaurants that prepare breakfast egg entrées: an EHS-Net study.

Salmonella enterica serotype Enteritidis (SE) is a common cause of foodborne illness in the United States. Foods prepared with raw shell eggs have often been associated with SE outbreaks. The federal government published the Egg Safety Action Plan in December 1999 that called for reduction of egg-preparation practices that may contribute to the survival and proliferation of SE. In seven states, an interview and brief site evaluation of 153 restaurants that prepare eggs during all hours of operation was conducted by the Environmental Health Specialists Network to determine the prevalence of such practices. Fifty-four percent (83 of 153) of restaurants pooled raw shell eggs not intended for immediate service. These pooled eggs were held a median of 4 h for scrambled eggs, 5.5 h for omelets, and 6 h for pancakes and French toast. Nearly 26% (39 of 152) of restaurants reported storing eggs at room temperature, and 5% (7 of 152) stored eggs on ice or in cold-water baths before cooking. Generally, eggs were cooked to 72 to 83 degrees C, which is above the recommended final cook temperature of 63 to 68 degrees C. Employees reported sanitizing utensils used to prepare eggs less than once every 4 h in 42% (57 of 136) of restaurants. Several areas were identified in which further emphasis might reduce egg-associated SE infections in accordance with Healthy People 2010 goals.

Consumer Product Safety↗
PubMed1992

A kinetic study of egg production, fecal egg output, and the rate of proglottid shedding in Hymenolepis nana.

To estimate the rate of shedding of the proglottids during normal development of Hymenolepis nana in mice, 2 parameters, i.e., egg production and fecal egg output, have been determined. Changes in the number of eggs/proglottid along the length of the worm showed that, not only in vitro but also in vivo, a considerable number of eggs is discharged in situ while the proglottids are still attached to the worm. The in situ egg discharge, however, accounts only for a small fraction of the eggs appearing in the feces, and it can be neglected in the estimation of the shedding of proglottids. In H. nana the larva rotates 90 degrees in the egg during its development. This seems to occur in a short period, quite in concert within each proglottid. The transition point (the proglottid where 50% of the eggs have begun rotating) can be a useful landmark to estimate the rate of proglottid shedding. Egg numbers at the transition points approximate the genuine egg production, because in situ egg discharge mostly occurs only after the proglottids have passed the transition point. The 3 processes, i.e., the rotation of the larva in the egg, the in situ egg discharge, and the shedding of proglottids, usually occur in an orderly way. However, on day 20 of infection, just before the worms are lost (or destrobilated), shedding of proglottids seems to be inhibited, whereas the other processes are apparently normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗