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PubMed2000

Changes in egg composition of American kestrels exposed to dietary polychlorinated biphenyls.

Changes in the quality of eggs of birds exposed to polychlorinated biphenyls (PCBs) have been described, but have never been directly attributed to PCBs. Polychlorinated biphenyl residues in eggs have been associated with reduced reproductive success and embryonic deformities in wild birds. Egg size and composition, specifically the amount of albumen, yolk, and water in an egg, also influence the growth and viability of embryos and hatchlings, and consequently the reproductive success of birds. To deter mine whether PCB exposure of adult birds affected the size and composition of their eggs, 25 pairs of captive American kestrels (Falco sparverius) were fed a mixture of PCB-spiked (1248:1254:1260) food to give an approximate exposure of 7 mg/kg body weight/d, beginning 1 mo prior to pairing, and continuing throughout the courtship, egg-laying, and incubation periods. This dietary level in the adult female kestrels resulted in mean total PCB residues in the eggs of 34.1 microg/g wet weight (geometric mean), which is environmentally relevant. PCB residues in eggs increased with the time of female exposure to the contaminated diet and laying date. Variation in egg size within PCB clutches was significantly greater than within control clutches, although absolute egg mass and volume did not differ markedly by treatment. Only infertile eggs and only one egg per clutch were used for egg composition analysis. Yolks in the PCB-contaminated eggs were heavier, with less wet and dry albumen relative to control eggs. Water content and eggshell thickness were not significantly affected by PCB exposure. These results suggest that eggs from the PCB treatment have relatively more lipid and less protein available for embryonic development. Changes in egg composition were not associated with egg size, lay date, ambient temperature, humidity, or precipitation, which are factors known to affect these variables in bird eggs. The PCB-induced changes in egg composition described here provide insight into possible mechanisms contributing to reduced reproductive performance in wild birds exposed to PCBs.

Administration, Oral↗
PubMedDate not supplied

Viability of some Salmonella strains in Algerian eggs.

Whole-egg and egg-white were inoculated with S. typhi murium, S. dublin, S. oranienburg and S. oslo separately and were stored at - 1 degrees C, + 4 degrees C and 26-28 degrees C. pH value was determined every day as well as the survival of the different inoculated Salmonella strains till the end of the experiment. Stored at - 1 degrees C in case of whole-egg, egg-yolk and egg-white, pH values were 7.0, 6.0 and 7.0 while the maximum values were 8.5, 8.0 and 9.0 respectively. The shortest survival period for Salmonella strains was 101 days in whole-egg, 103 days in egg-yolk and 36 days in egg-white, while the longest period was 114, 123 and 59 days respectively. The minimum pH values of whole-egg, egg-yolk and egg-white stored at + 4 degrees C were 6.5, 6.0 and 7.0 while the maximum values were 8.5, 8.5 and 10.0 respectively, 55, 66 and 30 days were the shortest survival periods for Salmonella strains inoculated in whole-egg, egg-yolk and egg-white while the maximum periods were 81, 80 and 67 days. The minimum pH values of whole-egg, egg-yolk and egg-white held at room-temperature, were 6.0, 6.0 and 7.5 while the maxima were 8.5, 8.5 and 10.0 respectively. The minimum survival period of the Salmonella strains inoculated in whole-egg, egg-yolk and egg-white was 52, 41 and 21 days, while the maximum periods were 63, 52 and 37 days respectively.

Animals↗
PubMed1997

Allergenic activity of heated and ovomucoid-depleted egg white.

BACKGROUND: No egg white products have been clearly proven to be hypoallergenic. The role of egg white proteins in allergic reactions to eggs is still debatable. OBJECTIVE: This study was designed to determine the importance of ovomucoid, an egg white protein, in the development of allergies to egg white. METHODS: We performed a double-blind, placebo-controlled food challenge in subjects with high levels of IgE antibodies for egg white to compare the allergenicities of heated and ovomucoid-depleted egg white, freeze-dried egg white, and heated egg white. Levels of IgE antibodies for egg white, ovomucoid, ovalbumin, ovotransferrin, and lysozyme were measured in serum by RAST. RESULTS: Twenty-one of 38 subjects with positive challenge responses to freeze-dried egg white had negative challenge responses to heated egg white, whereas 16 of 17 subjects (94.1%) with positive responses to heated egg white did not respond to the heated and ovomucoid-depleted egg white challenge. The subjects with positive challenge responses to freeze-dried egg white tended to have higher IgE antibody values to ovomucoid than those with negative responses. IgE antibody levels to ovomucoid were significantly higher in subjects with positive responses to a challenge with heated egg white than in those with no response. There were no significant differences in the levels of IgE antibodies to the other proteins, except ovomucoid, in the negative-response and positive-response groups in challenge tests with freeze-dried and heated egg white. CONCLUSION: The heated and ovomucoid-depleted egg white preparation was less allergenic than heated or freeze-dried preparations. Ovomucoid has a more important role in the pathogenesis of allergic reactions to egg white than other proteins in egg white.

Allergens↗
PubMed2005

Factors affecting the toxicity of methylmercury injected into eggs.

We developed a standardized protocol for comparing the sensitivities of the embryos of different bird species to methylmercury when methylmercury was injected into their eggs. During the course of developing this protocol, we investigated the effects of various factors on the toxicity of the injected methylmercury. Most of our experiments were done with chicken (Gallus domesticus), mallard (Anas platyrhynchos), and ring-necked pheasant (Phasianus colchicus) eggs, all of which were purchased in large numbers from game farms. A smaller amount of work was done with double-crested cormorant (Phalacrocorax auritus) eggs collected from the wild. Several solvents were tested, and corn oil at a rate of 1 microl/g egg contents was selected for the final standardized protocol because it had minimal toxicity to embryos and because methylmercury dissolved in corn oil yielded a dose-response curve in a range of egg concentrations that was similar to the range that causes reproductive impairment when the mother deposits methylmercury into her own eggs. The embryonic stage at which eggs were injected with corn oil altered mercury toxicity; at early stages, the corn oil itself was toxic. Therefore, in the final protocol we standardized the time of injection to occur when each species reached the morphologic equivalent of a 3-day-old chicken embryo. Although solvents can be injected directly into the albumen of an egg, high embryo mortality can occur in the solvent controls because of the formation of air bubbles in the albumen. Our final protocol used corn oil injections into the air cell, which are easier and safer than albumen injections. Most of the methylmercury, when dissolved in corn oil, injected into the air cell passes through the inner shell membrane and into the egg albumen. Most commercial incubators incubate eggs in trays with the air cell end of the egg pointing upward, but we discovered that mercury-induced mortality was too great when eggs were held in this orientation. In addition, some species of bird eggs require incubation on their sides with the eggs being rolled 180 degrees for them to develop normally. Therefore, we adopted a procedure of incubating the eggs of all species on their sides and rolling them 180 degrees every hour. Little has been published about the conditions of temperature, humidity, and the movements to which eggs of wild birds need to be subjected for them to hatch optimally under artificial incubation. Not unexpectedly, hatching success in an artificial incubator is generally less than what natural incubation by the parents can achieve. However, the survival of control embryos of most wild bird species was good (generally > or = 80%) up to within 1 or 2 days of hatching when we incubated the eggs at 37.5 degrees C (or 37.6 degrees C for gallinaceous species) at a relative humidity that resulted in an approximate 15% to 16% loss in egg weight by the end of incubation and by incubating the eggs on their sides and rolling them 180 degrees /h. To improve statistical comparisons, we used survival through 90% of incubation as our measurement to compare survival of controls with survival of eggs injected with graded concentrations of mercury.

Animals↗
PubMed2003

Contact chemosensory cues in egg bundles elicit male-male agonistic conflicts in the squid Loligo pealeii.

Male Loligo pealeii engage in frequent agonistic bouts to gain access to female mates while aggregated at communal egg beds. Male squids are attracted to eggs in the field and in the laboratory. It was recently demonstrated that visual detection followed by physical contact with egg capsules elicited male-male aggression. We tested specific physical and chemical features of the egg capsules that may cause this strong behavioral reaction. Male squids were presented with either natural or artificial egg stimuli and scored for four selected behaviors (egg touch, egg blowing, forward-lunge grab, and fin-beating), the last two of which are highly aggressive behaviors. First, squids were presented with natural eggs versus eggs sealed in agarose-coated tubes (ESACT), which eliminated both tactile and chemical stimuli. Second, males were presented with natural eggs versus eggs sealed in agarose coated tubes containing C18 Sep-Pak-purified extracts (TCPE) from squid egg capsules, which provided chemical cues from natural eggs without the physical stimulus of the egg capsules. Third, natural eggs versus heat-denatured eggs were tested to determine whether the active factor in natural eggs is heat-labile. Squids responded aggressively when contacting natural eggs and TCPE, whereas squids did not respond after touching ESACT or denatured eggs. These results suggest that aggressive behavior is elicited by a heat-labile factor that is embedded within squid egg capsules. This chemosensory cue appears to be a contact pheromone that stimulates the agonistic interactions that characterize the mating behavior of migratory squids on inshore spawning grounds.

Agonistic Behavior↗
PubMed2003

Does egg-sharing compromise the chance of donors or recipients achieving a live birth?

BACKGROUND: To evaluate the effect of egg-sharing and the outcome of assisted reproductive treatment (ART) in standard IVF/ICSI patients, egg-sharing donors and egg-sharing recipients. METHODS: Descriptive cohort study to evaluate 276 egg-sharing cycles involving 192 egg-sharers, 274 recipient cycles receiving eggs from egg-sharers and 1098 non-egg-sharing standard IVF/ICSI cycles from January 1998 to December 2002. Patients were divided into three groups: group A, egg-sharers; group B, non-egg-sharers, age <36 years, FSH <10 IU/l, BMI <30 kg/m(2); and group C, egg-sharing recipients, all ages. Duration and amount of gonadotrophin required to achieve follicular maturity, number of eggs collected and donated, fertilization rate, pregnancy rates and live birth rates were compared between donor, recipient and standard IVF/ICSI patients. The chi(2 )test was used to test for statistical significance (P < 0.05). RESULTS: There was no significant difference in pregnancy rate and live birth rate of egg-sharers, group A (42.0%, 33.0%), non-egg-sharers, group B (40.0%, 30.9%) and recipients, group C (41.4%, 28.6%). The number of oocytes collected, number of mature follicles and amount of gonadotrophin used was not significantly different between the two groups (A and B). The average number of embryos transferred and the mean number of eggs allocated between egg-sharers and recipients was not statistically different. CONCLUSION: Egg-sharing does not compromise the chance of achieving a pregnancy or live birth for the egg-sharer or the recipient as compared to standard IVF/ICSI patients. The egg-sharers were not at a higher potential risk of ovarian stimulation syndrome and there was no imbalance of egg allocation.

Adult↗
PubMed1992

Patterns of intracellular Ca2+ concentrations in fertilized bovine eggs.

Sperm-induced calcium (Ca2+) changes were examined in zona pellucida-intact, mature bovine eggs injected with the fluorescent Ca2+ indicator fura-2 dextran (fura-2 D). Fifty four percent (37/68) of the dye-injected, inseminated bovine eggs were fertilized and 43% (16/37) of the fertilized eggs exhibited Ca2+ elevations during the time of measurement. All (16/16) of the eggs with Ca2+ elevations were fertilized but none of the unfertilized eggs (0/31) showed intracellular Ca2+ elevations. Six of 13 eggs that were later examined and found to be fertilized at the time of the Ca2+ recordings did not show sperm-induced Ca2+ elevations. Fifty percent (8/16) of the eggs with Ca2+ elevations exhibited a single Ca2+ rise as a response to sperm penetration during the 60-min period in which these eggs were monitored. Twelve percent (2/16) of the eggs responded with two Ca2+ elevations spaced by 50- and 51-min intervals and 38% (6/16) of the eggs exhibited multiple elevations with intervals of 15-29 min. In the latter group, one egg was polyspermic. The mean amplitude of the sperm-induced Ca2+ elevations was 564 +/- 58 nM. Eggs with single elevations reached higher peak concentrations than eggs with multiple elevations (p < 0.05). The mean duration of the Ca2+ elevations was 166 +/- 13 sec and was similar among eggs with different Ca2+ patterns. The first elevations detected occurred at a mean of 6.6 +/- 0.5 h after insemination. Fertilization in this study was confirmed by looking at pronuclear formation 16 h post-insemination or by DNA staining immediately after the fluorescence readings. Eggs exhibiting Ca2+ elevations ranged in stage of fertilization from just penetrated to pronuclear. Injection of inositol 1,4,5 trisphosphate (5 microM in the injection pipette) into 6 bovine eggs induced an immediate Ca2+ elevation with a mean peak Ca2+ value of 700 +/- 60 nM and a mean duration of 103 +/- 21 sec. Incubation of bovine eggs with 200 microM thimerosal induced periodic Ca2+ rises. The mean number of Ca2+ elevations observed in 35 min of recordings was 3.0 +/- 0.5 (n = 9, range 1-5). The mean peak Ca2+ value of the first thimerosal-induced Ca2+ elevation was 990 +/- 210 nM. The results of this study indicate that fertilization can evoke intracellular Ca2+ elevations in bovine eggs and that the periodicity of these Ca2+ elevations is different among eggs. Furthermore, both inositol 1,4,5-trisphosphate and thimerosal were able to induce intracellular Ca2+ release in bovine eggs.

Analysis of Variance↗
PubMed1997

[Assessment of allergenic activity of heated and ovomucoid-depleted egg white].

We investigated allergenic activity of heated and ovomucoid (OM)-depleted egg white by RAST inhibition tests, skin tests and and oral challenge tests. Freeze-dried egg white, OM and ovalbumin (OA) were coupled with CNBr-activated paper discs. Freeze-dried, heated, and heated and OM-depleted egg white antigens were used as inhibitors in RAST inhibition tests. Freeze-dried egg white significantly inhibited the IgE-binding to freeze-dried egg-white-, OM- and OA-discs. Heated egg white showed a significant inhibition against only OM-disc, but heated and OM-depleted egg white didn't effectively suppress IgE-binding to all discs. Fifty-six patients were subjected for skin tests and 27 patients for oral challenge tests with freeze-dried egg white, heated egg white and heated and OM-depleted egg white. Eighteen of 25 subjects with positive prick tests results to freeze-dried egg white showed negative results to heated egg white. Four of 7 cases with positive prick test results to heated egg white gave negative results to heated and OM-depleted egg white. 20-minutes patch tests showed almost similar results to prick tests. Four of 8 subjects showing positive oral challenge tests with freeze-dried egg white were negative to heated egg white. All of 4 with positive oral challenge tests by heated egg white were negative results to heated and OM-depleted egg white. These evidence indicated that heated and OM-depleted egg white was more hypoallergenic than heated egg white.

Allergens↗
PubMedDate not supplied

[Bird-egg syndrome in children].

Allergy to egg is highly frequent in childhood. In general, children allergic to egg react principally to the ingestion of egg white. Egg yolk contains various proteins but the major allergens are contained in egg white. The principal allergens are ovalbumin, ovomucoid, ovotransferrin, and lysozyme. These proteins have been sequenced. In some cases, a relationship between type I hypersensitivity with respiratory symptoms due to bird antigens and allergy to egg yolk has been described. This association is known as bird-egg syndrome, which is caused by sensitization to chicken serum albumin (alpha -livetin) and is characterized by the development of respiratory and gastrointestinal symptoms after egg intake or after contact with bird antigens. The initial symptoms are usually asthma with or without rhinoconjunctivitis due to contact with birds. Individuals first become sensitized to bird proteins (feathers, excrement, serum and meat) and subsequently develop egg allergy. Although bird-egg syndrome has been described principally in adults, especially in women, it can also affect children in whom the syndrome presents certain differentiating characteristics in relation to the more common sensitization to egg white. Gastrointestinal and respiratory symptoms are more common than cutaneous symptoms and sensitization to egg yolk is more frequent than that to egg white. In children with allergy to birds and egg, egg allergy is usually more persistent; tolerance is not always achieved and develops later. Sensitization to other aeroallergens is also greater in individuals with allergy to birds and egg. Sensitization to egg sometimes precedes respiratory sensitization to bird proteins, a process known as bird-egg syndrome. By way of example, the case of a child who clinically presented bird-egg syndrome is presented at the end of this review.

Adult↗
PubMed2004

Effects of egg yolk during the freezing step of cryopreservation on the viability of goat spermatozoa.

Four experiments were conducted to investigate the effects of egg yolk during the freezing step of cryopreservation (namely, the process except for the cooling step), on the viability of goat spermatozoa. The effects of egg yolk on sperm motility and acrosome integrity during the freezing step were investigated in Experiment 1. Spermatozoa diluted with Tris-citric acid-glucose (TCG) solution containing 20% (v/v) egg yolk were cooled to 5 degrees C, washed, and then frozen in TCG with egg yolk (TCG-Y), TCG without egg yolk (TGG-NY), 0.370 M trehalose with egg yolk (TH-Y), or trehalose without egg yolk (TH-NY). All extenders contained glycerol. In frozen-thawed spermatozoa, the inclusion of egg yolk in the freezing extenders increased (P<0.05) percentages of motile sperm, progressively motile sperm, and the recovery rate (ratio of post-thaw to pre-freeze values), but decreased (P<0.05) acrosomal integrity. Moreover, extenders with trehalose had better (P<0.05) post-thaw sperm viability. In Experiment 2, the effects of egg yolk on acrosome status before and after freezing were studied. Egg yolk significantly decreased the proportion of intact acrosomes before freezing, leading to fewer (P<0.05) intact acrosomes post-thaw and lower (P<0.05) recovery rates for intact acrosomes. In Experiment 3, including sodium dodecyl sulfate (SDS) in a diluent containing egg yolk tended to preserve the acrosome compared with the egg yolk containing diluent free of SDS, however, spermatozoa had a lower (P<0.05) proportion of intact acrosomes than those in a yolk-free diluent. However, after cooling, spermatozoa were diluted with a glycerolated extender containing egg yolk. Therefore, the objective of Experiment 4 was to explore whether the egg yolk or glycerol was responsible for the reduced intact acrosome percentage. In this experiment, after cooling and washing the spermatozoa were diluted in TCG with glycerol and/or egg yolk. The combination of glycerol and egg yolk in the extender reduced (P<0.05) the proportion of intact acrosomes compared with egg yolk or glycerol alone. In conclusion, the inclusion of egg yolk significantly improved sperm motility, indicating its beneficial effects during the freezing step of cryopreservation; trehalose appeared to synergistically increase its cryoprotective effects. Furthermore, although neither glycerol nor egg yolk per se affected the proportion of intact acrosomes, the combination of the two significantly reduced the proportion of acrosome-intact spermatozoa.

Acrosome↗
PubMed2002

Eggshell conductance, embryonic growth, hatchability and embryonic mortality of broiler breeder eggs dipped into ascorbic acid solution.

1. Eggs from a broiler breeder flock between 25 and 29 weeks of age were dipped into solutions of various concentrations of ascorbic acid (AA) for up to 2 min, in order to evaluate its effects on eggshell conductance (EC), amniotic fluid pH, albumen height and pH, embryonic weight and hatchability. 2. Three experiments were conducted and the following treatments were used: control, non-dipped (CND); control, water-dipped (CWD); 10 g AA/l (AA1); 20 g AA/l (AA2) and 30 g AA/l (AA3). Measurements of EC before and after dipping were made in experiments 1 and 2 in eggs from hens at 25 and 27 weeks of age, respectively. Albumen height and pH were measured after dipping the eggs in experiment 2. In experiment 3, egg weight loss, embryonic weight and amniotic fluid pH at 14 d of age, hatchability percentage (HP), and embryonic mortality were measured in eggs from hens at 29 weeks of age. 3. AA treatment of eggs and dipping period of time (1, 1.5 and 2 min) increased EC of eggs from hens at 25 and 27 weeks of age. 4. AA3 treatment for 2 min reduced albumen height and increased albumen pH of eggs when compared with the CND treatment in eggs from hens at 27 weeks of age. 5. HP of AA1-treated eggs from hens at 29 weeks of age was higher than that of the CND treatment. AA2 and AA3 treatments of eggs reduced HP and increased the percentage of non-pips when compared with any of the other treatments. 6. AA2 and AA3 treatments of eggs increased egg weight loss when compared with the control treatments (CND and CWD). Dipping treatment did not influence amniotic fluid pH or embryo weight expressed as a percentage of initial egg weight. 7. It is concluded that dipping hatching eggs into AA solution increased EC of eggs. Dipping eggs into 10 g AA/l for a period of 2 min increased HP in eggs from hens at 29 weeks of age, although this was not associated with a significant increase in egg weight loss.

Albumins↗
PubMed1994

Modulation of spermatozoa and zona pellucida properties by the soluble acrosome reaction-inducing factor of the ovulated egg-cumulus complex.

Three sources of hamster periovulatory fluids (+/- heat inactivation at 56 degrees C), with bovine serum albumin (BSA) as control, were tested for effects on penetration of three classes of eggs by hamster sperm precapacitated in BSA. These fluids were a soluble extract of cumulus oophorus fluid (COF) from the ovulated hamster egg-cumulus complex, serum, and follicular fluid. Egg types were ovulated, salt-stored (ovulated), and follicular. In both COF and serum, there were significant differences among egg types in mean penetration, and significant effects of fluid addition. In contrast, there was no effect of follicular fluid and no differences between follicular and stored eggs. For the follicular eggs (combined data, normalized, ranked), patterns of response to the three factors (+/- heating) were different: only unheated COF and heated serum increased penetration significantly above BSA control levels (average rank 20.2, 41.4, 38, for BSA, COF (unheated), serum (heated), respectively). This indicated that the active component in COF was heat labile, not present in either serum or follicular fluid, and, therefore, of oviductal origin. Oviduct and/or COF exposure of eggs and sperm was tested for effects as an acrosome reaction inducing factor (ARIF) for acrosome reactions (AR; zona-bound and free-swimming sperm) and on sperm:zona binding and penetration. The COF ARIF for free-swimming sperm AR was heat stable. Penetration of follicular eggs increased after incubation in COF prior to sperm addition, but a greater response occurred when COF was added to eggs with sperm. In kinetic experiments, 25 min following sperm attachment, follicular eggs had lost 41% of initially bound sperm, vs. 23% for ovulated eggs, and had only 16 AR sperm/egg, vs. 26 for ovulated. Follicular eggs incubated in COF (then washed three times) had the same number of bound AR sperm as ovulated eggs. Acid solubilized zona pellucida (ASZP) from ovulated eggs was more effective as an ARIF per zona than ASZP from follicular eggs. Zonae of follicular eggs, as evidenced by dissolution times in beta-mercaptoethanol (beta-MEOH), were not "harder" than those of ovulated eggs. There were differences in lectin binding antigens on zonae of both fresh and stored, follicular and ovulated, eggs. We conclude that multiple biological factors orchestrate sperm:egg interactions in the ampulla. Our data are consistent with the presence of at least three effective components: 1) the oviductal lectin-binding antigen (ZPO or oviductin), 2) an additional heat-labile component, and 3) the heat-stable ARIF for free-swimming sperm.

Animals↗
PubMed2000

Biology and field performance of gryon clavigrallae (Hymenoptera: Scelionidae), an egg parasitoid of Clavigralla spp. (Hemiptera: Coreidae) in India.

The biology and impact of Gryon clavigrallae Mineo, an egg parasitoid of Clavigralla scutellaris Spinola and C. gibbosa (Westwood), was investigated. The calculated developmental threshold temperatures for females and males were 15.6 degrees C and 15.8 degrees C, respectively. Emergence exceeded 94% at temperatures between 22 and 30 degrees C. Adult females lived on average 28-96 days when fed with honey. Without food, adults lived < 6 days. Mean fecundity was 56.4 eggs per female. A significant trend of lower fecundity after longer periods of host deprivation was observed. Gryon clavigrallae females successfully oviposited in host eggs of all ages though eggs < 4 days old were preferred. Total host handling times were significantly longer on C. gibbosa eggs (23.5 min) than on C. scutellaris eggs (12.0 min). Females readily distinguished parasitized from non-parasitized host eggs. Superparasitism was observed when few or no unparasitized eggs were available. Eggs of the two Clavigralla species can be separated by surface structure and condition after eclosion. Clavigralla scutellaris laid significantly larger egg clusters than C. gibbosa (19.9 versus 10.5 eggs per cluster). Gryon clavigrallae was present as soon as the first Clavigralla spp. egg clusters were found on pigeonpea. The percentage of egg clusters parasitized increased early in the season with egg cluster density and remained high (up to 83%) despite fluctuations in host density. Overall, G. clavigrallae parasitized 40 and 58% of C. gibbosa and C. scutellaris eggs. The percentage of egg clusters parasitized and the number of eggs parasitized per cluster increased significantly with egg cluster size. The overall parasitoid sex ratio was highly female biased but varied with the number of eggs parasitized per cluster.

Animals↗
PubMed2002

Fertility of male and female emus (Dromaius novaehollandiae) as determined by spermatozoa trapped in eggs.

Changes in the fertility status of 10 pairs of emus were investigated using egg break-out and numbers of sperm in the perivitelline membrane of the germinal disc (GD) region. After the sexes were separated, sperm in consecutive eggs declined approximately logarithmically at a mean (+/-SEM, n = 10 females) rate of -0.148 +/- 0.021 per log day. Sperm continued to be detected in eggs for 16.5 +/- 1.7 days during which 5.6 +/- 0.6 fertilized eggs were laid. Fertilized eggs that did not contain detectable sperm were laid by five females for a further 2.2 +/- 0.9 days. Based on break-out fertility, the fertile period continued for up to 18.7 +/- 2.1 days, for which the mean number of laid eggs was 6.3 +/- 0.8. An egg with a 50:50 chance of being fertilized would contain 3.5 sperm mm(-2) of GD. Based on the sperm decline model, an egg containing that many sperm would be laid 21 days after the last copulation. In emus that were not separated and allowed to incubate their eggs (n = 3 pairs), the number of sperm in eggs laid before and during incubation declined in a manner similar to that after the last copulation and egg-laying stopped after the females had laid 3.3 +/- 0.3 eggs. After incubation was terminated, females resumed laying within 8.3 +/- 1.2 days and the number of sperm in eggs gradually increased but it did not return to pre-incubation levels. In non-incubating emus (three pairs), the number of sperm in eggs declined as laying progressed, although lit was higher during the period when the first seven eggs were laid than during the period when the rest of eggs were laid (214 +/- 39 v.100 +/- 16 sperm mm(-2) of GD). Sperm numbers varied between successive eggs but a sharp increase followed by a decrease acted as an indicator of recent copulation. There were 8.7 +/- 0.3 such increases per laying period (one per 2.8 +/- 0.2 eggs), a frequency that suggests that emus copulate once weekly. In conclusion, as long as a female emu is supplied with sperm on a weekly basis, she will be fertile but, when copulations stop, she will stop laying soon after. Male fertility appears to fall towards the end of the laying season and it can be affected by egg incubation at any time of the season.

Animals↗
PubMed2004

Patient experiences of an "egg sharing" programme.

INTRODUCTION: This paper reports on a qualitative empirical study of the experiences of women (and their partners) attending one UK assisted conception unit, who have considered egg sharing. AIMS: In the absence of any published research of the experiences of people contemplating egg sharing and the considerable concerns that egg sharing had generated (for an overview see Blyth, 2002), the major purpose of the study was to examine the experiences not only of those who had considered and proceeded with egg sharing but also those who had considered, but had then decided against, egg sharing. In addition, since the views of male partners are frequently overlooked in studies of assisted conception treatment (cf. Ahuja, Mostyn, & Simons, 1997) the project actively sought the involvement of the women's partners. The study was designed to explore couples' motivation for egg sharing, their experiences of treatment, attitudes regarding information about egg sharing treatment and outcomes, and attitudes towards egg sharing. METHODS: The centre sent a written invitation to participate in the study to all women who had indicated an interest in egg sharing and who had received both information and counselling in advance of proceeding (n = 60). Of these, 43 had decided to proceed after the counselling session and 17 had decided not to do so. Expressions of interest in participating in the study were received from 20 women: (a) five women had proceeded with egg sharing but had not been successful with their own treatment at the time of interview--all husbands/partners also participated (n = 10); (b) seven women had proceeded with egg sharing and had conceived (one of whom had conceived unexpectedly without assisted conception services)--5 couples and 2 women participated (n = 12); (c) six women decided to proceed with egg sharing, however an insufficient number of eggs were available following egg retrieval to enable egg sharing to take place--all husbands/partners also participated (n = 12); (d) two women decided not to proceed--and both husbands/partners participated (n = 4). The study data were derived from retrospective semi-structured interviews conducted by the author with these 20 women and 18 husbands/partners. Respondents also completed a paper exercise following the interview indicating their level of agreement or disagreement with a number of statements relating to egg sharing that were derived from responses to the HFEA's consultation on the withdrawal of payment to donors (HFEA 1998a.). While there was an overall 33% response rate, the response rate for those who had decided to proceed with egg sharing (41.9%) was greater than for those who had decided not to proceed (11.8%). Consequently, this study under-represents the views of women and their partners who had considered, but then rejected, egg sharing. Couples agreeing to participate in the research were given a choice of being interviewed together or separately and in their own home or at an alternative venue. This choice of separate or joint interviews was offered as part of the explicit effort to involve men in the study and to maximize participant choice. Twelve couples agreed to be interviewed separately; six couples were interviewed together and two women whose partners did not take part in the study were interviewed alone. There was no evidence of any significant differences in interview data between joint and separate interviews. Indeed, there was little disagreement between partners at all; this is probably not surprising, given that they will have discussed their decision about egg sharing together and will be aware of each other's views about at least some of the issues discussed during interview. All except four interviews took place in respondents' own homes. Two interviews took place in the centre at the respondents' requests and two interviews were conducted by telephone because of geographical considerations. All interviews were audio-recorded with respondents' permission and subsequently transcribed verbatim. The research was conducted in accordance with the British Psychological Society Statement of Ethical Principles for Conducting Research with Human Subjects (British Psychological Society, 2002). Ethical approval was given by the University of Huddersfield Ethics Committee.

Female↗
PubMed1997

Sperm-egg fusion is the prelude to the initial Ca2+ increase at fertilization in the mouse.

Fusion of sperm and egg plasma membranes is an early and essential event at fertilization but it is not known if it plays a part in the signal transduction mechanism that leads to the oscillations in the cytoplasmic free Ca2+ concentration ([Ca2+]i) that accompany mammalian egg activation. We have used two independent fluorescence methods and confocal microscopy to show that cytoplasmic continuity of egg and sperm precedes the onset of the first [Ca2+]i increase in mouse eggs. The Ca2+ indicator dye Ca2+-green dextran was microinjected and its transfer from egg to sperm was monitored. We found that it occurred before, and without a requirement for, any detectable [Ca2+]i increase in the egg. In separate experiments [Ca2+]i changes were recorded in populations of eggs, using fura red, and the eggs fixed at various times after some of the eggs had shown a [Ca2+]i transient. Fusion of the sperm and egg was then assessed by Hoechst dye transfer. All eggs that showed a [Ca2+]i increase had a fused sperm but more than half of the eggs contained a sperm but had not undergone a [Ca2+]i increase. These data indicate that sperm-egg fusion precedes [Ca2+]i changes and we estimate that the elapsed time between sperm-egg fusion and the onset of the [Ca2+li oscillations is 1-3 minutes. Finally, sperm-egg fusion was prevented by using low pH medium which reversibly prevented [Ca2+]i oscillations in eggs that had been inseminated. This was not due to disruption of signalling mechanisms, since [Ca2+]i changes still occurred if low pH was applied after the onset of oscillations at fertilization. [Ca2+]i changes also occurred in eggs in low pH in response to the muscarinic agonist carbachol. These data are consistent with the idea that the [Ca2+]i signals that occur in mammalian eggs at fertilization are initiated by events that are closely coupled to the fusion of the sperm and egg membranes.

Acrosome↗
PubMed1998

Egg culture: the foundation.

Ralph Brinster began his classic work on egg culture more than 35 years ago. His interest in mammalian egg culture had developed, in part, as a consequence of his experiences with animal breeding and reproduction that he gained while growing up on a farm. Ralph decided early in his career that an in vitro approach to culturing eggs would provide a powerful tool with which to study the development of these cells. Beginning at the close of the 19th century, a number of investigators had performed in vitro studies on egg culture and the related area of egg transfer; however, the ability to recover and transplant eggs had reached a much higher level of perfection than had culture. Eggs of many species could be successfully transferred, but there was no reliable technique for egg culture. In 1963, Ralph reported a method for culturing eggs in microdrops of medium under oil (Brinster, 1963), which has become universally used. Two years later, he identified pyruvate as the central and essential energy source for early stages of mouse eggs (Brinster, 1965b). These two developments revolutionized in vitro studies of mammalian eggs and issued in an era of intense research activity concerning egg culture and egg manipulation. Effective formulations of culture media could now be developed to allow routine in vitro maintenance of eggs, and important parameters for these recipes were soon determined. It was quickly established that the requirement for pyruvate as an energy source exists at ovulation in many species and is already present in germ cells of the mouse fetus. The metabolic activity of the fertilized mouse egg was shown to be low and comparable to bone; however, four days later, at the blastocyst stage of development, the metabolic activity was comparable to brain. Thus, a foundation of understanding about the biology of early mammalian eggs was established between 1960 and 1970, and subsequent studies have broadened this understanding. However, the greatest impact of a simple, reliable egg culture method has been to provide the ability to perform complicated manipulative procedures on preimplantation stages of mammalian embryos. In no area has this been more important than in development of transgenic animals. All methods for generating germ line genetic modifications rely on the ability to maintain and manipulate eggs and early developmental stages in vitro without loss of developmental competence. The importance of efficient egg culture to manipulation and transgenesis is fundamental and enabling.

Animals↗
PubMed2000

Estimating the annual fraction of eggs contaminated with Salmonella enteritidis in the United States.

Using available data on the occurrence of Salmonella enteritidis (SE) in US layer flocks and eggs, and a probabilistic scenario tree method, an estimate of the fraction of SE-contaminated eggs produced annually is derived with attendant uncertainty. In lieu of a definitive prevalence survey, the approach presented here provides insight to the relative contribution of various pathways leading to contaminated eggs. A Monte Carlo model with four branches is developed. The first branch predicts the proportion of all US flocks that are SE-affected. The second branch apportions SE-affected flocks into three categories (high, moderate, and low level affected flocks) based on population-adjusted epidemiologic data. The third branch predicts the proportion of affected flocks that are molted and producing eggs during a high risk period subsequent to molt. The fourth branch predicts the fraction of contaminated eggs produced by flocks of the type described by the pathway (e.g. high level affected flocks that are not molted) based on egg sampling evidence from naturally infected flocks. The model is simulated to account for uncertainty in the data used to estimate the branch probabilities. Correlation analysis is used to estimate the sensitivity of model output to various model inputs. The output of this model is an uncertainty distribution for the fraction of all eggs that are SE-contaminated during 1 year of production in the US. The expected value of this distribution is approximately one SE-affected egg in every 20,000 eggs annually produced, and the 90% certainty interval is between one SE-contaminated egg in 30,000 eggs, and one SE-contaminated egg in 12,000 eggs. The model estimates that an average of 14% of all eggs (i.e. contaminated and not contaminated) from affected flocks are produced by high level, non-molted affected flocks, but these flocks are estimated to account for more than two-thirds of the total fraction of contaminated eggs produced annually. Sensitivity analysis also suggests that the proportion of affected flocks that are high level flocks - and the egg contamination frequency for these types of flocks - are the most sensitive model inputs. The model's pathways provide a framework for evaluating interventions to reduce the number of contaminated eggs produced in the US. Furthermore, sensitivity analysis of the model identifies those inputs whose uncertainty is most influential on the model's output. Future farm-level research priorities can be established on the basis of this analysis, but public policy decisions require a fuller exposure assessment and dose-response analysis to account for microbial growth dynamics, meal preparation, and consumption demographics among US egg consumers.

Animals↗