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PubMed2004

Membrane and cortical abnormalities in post-ovulatory aged eggs: analysis of fertilizability and establishment of the membrane block to polyspermy.

Fertilization at increased times after ovulation is associated with poor reproductive outcomes. This study examines the effects of post-ovulatory ageing on egg membrane function through analyses of mouse eggs collected at 13 and 22 h post-HCG ('young' and 'aged' eggs, respectively). Experiments in which fertilized zona pellucida-free young and aged eggs are challenged with additional sperm reveal that aged eggs are less able to establish a membrane block to prevent polyspermy, since sperm penetrate 24% of fertilized aged eggs but are unable to penetrate fertilized young eggs. This is not due to a failure of aged eggs to respond to fertilization, as the extent of sperm-induced cortical granule exocytosis is similar in aged and young eggs. Post-ovulatory ageing also affects egg membrane receptivity to sperm as a subset of zona pellucida-free aged eggs are slow to fertilize or resistant to fertilization. Sperm binding to young and aged eggs is similar, but aged eggs develop cytoskeletal abnormalities that may affect membrane/cortical function, such as the ability of the egg membrane to support sperm-egg fusion. These data demonstrate that the poor reproductive outcomes associated with post-ovulatory ageing could be a result of reduced fertilization, due to reduced egg membrane receptivity to sperm, or a result of increased incidence of polyspermy, due to the reduced ability to establish a membrane block to polyspermy. This analysis of egg membrane function deficiencies provides insights into post-ovulatory ageing and has implications for assisted reproductive technologies.

Animals↗
PubMed1989

Bacterial Colonization of Cod (Gadus morhua L.) and Halibut (Hippoglossus hippoglossus) Eggs in Marine Aquaculture.

Aquaculture has brought about increased interest in mass production of marine fish larvae. Problems such as poor egg quality and mass mortality of fish larvae have been prevalent. The intensive incubation techniques that often result in bacterial overgrowth on fish eggs could affect the commensal relationship between the indigenous microflora and opportunistic pathogens and subsequently hamper egg development, hatching, larval health, and ongrowth. Little information about the adherent microflora on fish eggs is available, and the present study was undertaken to describe the microbial ecology during egg development and hatching of two fish species of potential commercial importance in marine aquaculture. Attachment and development of the bacterial flora on cod (Gadus morhua L.) eggs from fertilization until hatching was studied by scanning electron microscopy. The adherent microflora on cod (G. morhua L.) and halibut (Hippoglossus hippoglossus) eggs during incubation was characterized and grouped by cluster analysis. Marked bacterial growth could be demonstrated 2 h after fertilization, and at hatching eggs were heavily overgrown. Members of the genera Pseudomonas, Alteromonas, Aeromonas, and Flavobacterium were found to dominate on the surface of both cod and halibut eggs. The filamentous bacterium Leucothrix mucor was found on eggs from both species. While growth of L. mucor on halibut eggs was sparse, cod eggs with a hairy appearance due to overgrowth by this bacterium close to hatching were frequently observed. Vibrio fischeri could be detected on cod eggs only, and pathogenic vibrios were not detected. Members of the genera Moraxella and Alcaligenes were found only on halibut eggs. Caulobacter and Seliberia spp. were observed attached to eggs dissected from cod ovaries under sterile conditions, indicating the presence of these bacteria in ovaries before spawning. Adherent strains did not demonstrate antibiotic resistance above a normal level. Attempts to regulate the egg microflora by incubation of gnotobiotic eggs with defined antibiotic-producing strains did not result in persistent protection against subsequent colonization by the microflora of the incubator.

Journal Article↗
PubMed2005

Microbial health risk posed by table eggs in Trinidad.

A survey of the microbial quality of table eggs sold in Trinidad was conducted. For 23 poultry layer farms each visited twice approximately 1 month apart, 25 pooled eggs constituted a composite sample, for 14 shopping malls each visited twice approximately 1 month apart, six pooled eggs made a composite sample and for a total of 102 other retailers across the country each visited once over a 4-month period, six pooled eggs constituted a composite sample. Swabs of egg shells and egg content were tested for selected bacteria. Twenty-four (13.0%), 68 (37.0%), and two (1.1%) of a total of 184 composite eggs (shells, egg content or both) sampled were positive for Salmonella, Escherichia coli, and Campylobacter respectively. All 184 samples tested were negative for Listeria spp. Salmonella was recovered from seven (3.8%) egg shell samples only compared with 14 (7.6%) egg content samples only positive for the pathogen. Fifty-two (28.3%) egg shell samples and seven (3.8%) egg content samples were positive for E. coli. Both isolates of Campylobacter coli originated from egg contents. Of a total of 24 composite egg samples positive for Salmonella, eight different serotypes of Salmonella were isolated from a total of 24 Salmonella-positive composite eggs of which S. Enteritidis was the most prevalent, 58.3% (14/24). Salmonella Georgia was isolated for the first time in Trinidad. Failure to properly handle or heat table eggs sold in Trinidad poses a potential health hazard to consumers because of their poor microbial quality.

Animals↗
PubMed2005

[Allergenic activity of non-calcinated egg shell calcium].

BACKGROUND: There is few data to prove the safety of egg shell calcium as allergen. Especially, non-calcinated egg shell calcium is not allowed to use without the description of origin of egg on food labels in Japan. METHOD: We evaluated the possibly contaminated egg allergens in commercial non-calcinated egg shell calcium made from egg by in vitro methodologies (SDS-PAGE, western blotting, inhibition ELISA and sandwich ELISA) and by single-blind oral non-calcinated egg shell calcium challenge on 6 egg hypersensitivity patients. RESULTS: The allergenic activity of non-calcinated egg shell calcium was almost negligible compared to egg white by all in vitro methods. Furthermore, six patients with egg hypersensitivity were unresponsive to oral non-calcinated egg shell calcium challenge test. CONCLUSION: These results indicate that there is little contamination of egg white in non-calcinated egg shell calcium, and that the allergenic activity of non-calcinated egg shell calcium is equivalent to that of calcinated egg shell calcium.

Allergens↗
PubMed2004

Cestrum diurnum leaf as a source of 1,25(OH)2 Vitamin D3 improves egg shell thickness.

A continuing concern of the poultry industry is the high incidence (12%) of egg losses in the laying house due to poor egg shell quality. Calcium (Ca) homeostasis is a key factor in egg shell formation. The economy of Ca utilisation is under the control of Vitamin D(3), particularly its active metabolite 1,25-dihydroxy cholecalciferol [1,25(OH)(2)D(3)]. Supplementation of 1,25(OH)(2)D(3) has been shown to increase specific gravity, shell thickness and shell weight of the egg. However, commercially available synthetic 1,25(OH)(2)D(3) is very expensive. Earlier studies from our Institute [Phytochemistry 37 (1994) 677] have identified a cheap, natural and rich source of 1,25(OH)(2)D(3) in the leaves of Cestrum diurnum (CD), a member of the Solanaceae family. In this study, CD leaves were explored as a source of 1,25(OH)(2)D(3) in the feed of layer birds to improve the egg shell thickness. Fifteen-week-old white leghorn layers were divided into four treatments of 60 birds each and as follows: (I) normal diet with Vitamin D(3), (II) normal diet with Vitamin D(3) + CD, (III) normal diet without Vitamin D(3) and, (IV) normal diet without Vitamin D(3) + CD powder. CD leaf powder was incorporated in to the feed at 0.3% level. The experimental feeding was continued up to 72 weeks of age of the birds. Weekly food intake and daily egg production were noted throughout the experimental period and the specific gravity of the eggs, feed consumed to lay one egg and egg shell thickness were determined. Incorporation of CD leaves in the feed had the maximal effect on all the parameters studied. The feed consumed to lay one egg was 20 g less than the control group. The specific gravity of the egg was higher by 0.005, than the control egg, indicating a 5% decrease in the breakage of eggs in CD fed chicks. Also there was a significant increase (P < 0.001) in egg shell thickness. The data suggest that incorporation of CD leaf powder in the feed of poultry layers increased the egg shell thickness, which in turn could decrease the economic loss due to breakage of eggs.

Animals↗
PubMed2006

The evolution of egg colour and patterning in birds.

Avian eggs differ so much in their colour and patterning from species to species that any attempt to account for this diversity might initially seem doomed to failure. Here I present a critical review of the literature which, when combined with the results of some comparative analyses, suggests that just a few selective agents can explain much of the variation in egg appearance. Ancestrally, bird eggs were probably white and immaculate. Ancient diversification in nest location, and hence in the clutch's vulnerability to attack by predators, can explain basic differences between bird families in egg appearance. The ancestral white egg has been retained by species whose nests are safe from attack by predators, while those that have moved to a more vulnerable nest site are now more likely to lay brown eggs, covered in speckles, just as Wallace hypothesized more than a century ago. Even blue eggs might be cryptic in a subset of nests built in vegetation. It is possible that some species have subsequently turned these ancient adaptations to new functions, for example to signal female quality, to protect eggs from damaging solar radiation, or to add structural strength to shells when calcium is in short supply. The threat of predation, together with the use of varying nest sites, appears to have increased the diversity of egg colouring seen among species within families, and among clutches within species. Brood parasites and their hosts have probably secondarily influenced the diversity of egg appearance. Each drives the evolution of the other's egg colour and patterning, as hosts attempt to avoid exploitation by rejecting odd-looking eggs from their nests, and parasites attempt to outwit their hosts by laying eggs that will escape detection. This co-evolutionary arms race has increased variation in egg appearance both within and between species, in parasites and in hosts, sometimes resulting in the evolution of egg colour polymorphisms. It has also reduced variation in egg appearance within host clutches, although the benefit thus gained by hosts is not clear.

Animals↗
PubMed1977

The effect of feeding magnesium-enriched diets on the quality of the albumen of stored eggs.

1. Pullets were given from 1-d-old diets containing 1-6, 4-1, 8-1 and 12-0 g Mg/kg. Only small effects of these diets on live weight, food consumption, egg number, egg weights or egg-shell thickness were observed except at the highest level (12-0 Mg/kg) which caused diarrhoea and an appreciable lowering of the live weight of growing pullets. A further group was given from point-of-lay a diet containing 9-3 g Mg/kg. 2. Eggs laid on 3 consecutive days from each of eighteen hens were collected at intervals of 3 weeks until the birds were 68-5 weeks old. Eggs laid on the 3rd day were used to determine the initial proportion of thick egg-white present and also the concentration of Mg, Ca, Na and K in the thick egg-white. Eggs laid on the 1st and 2nd days were stored at 20 degrees for 20 d to establish the proportion of thick egg-white remaining after storage. 3. With the unsupplemented diet the proportion of residual thick egg-white after storage of eggs for 20 d at 20 degrees was 306, 161 and 305 mg/g total egg-white when the hens were 26-5, 53-5 and 68-5 weeks of age respectively. When the diet containing 9-3 g Mg/kg was given, the proportion of thick egg-white after storage remained approximately 400 mg/g throughout the period of the trial. 4. The mean Mg concentration in the thick egg-white of eggs laid by hens given unsupplemented diets was 5-77 mM. The addition of extra Mg to the diet increased the content of Mg in the thick egg-white, for example when the diet contained 9-3 g Mg/kg the mean concentration rose to 7-69 mM.

Animal Feed↗
PubMed1999

Life-History Consequences of Divergent Selection on Egg Size in Drosophila melanogaster.

Life histories are generally assumed to evolve via antagonistic pleiotropy (negative genetic correlations) among traits, and trade-offs between life-history traits are typically studied using either phenotypic manipulations or selection experiments. We investigated the trade-off between egg size and fecundity in Drosophila melanogaster by examining both the phenotypic and genetic relationships between these traits after artificial selection for large and small eggs, relative to female body size. Egg size responded strongly to selection in both directions, increasing in the large-egg selected lines and decreasing in the small-egg selected lines. Phenotypic correlations between egg size and fecundity in the large-egg selected lines were negative, but no relationship between these traits occurred in either the control or small-egg selected lines. There was no negative genetic correlation between egg size and fecundity. Total reproductive allocation decreased in the small-egg selected lines but did not increase in the large-egg lines. Our results have three implications. First, our selection procedure may have forced females selected for large eggs into a physiological trade-off not reflected in a negative genetic correlation between these traits. Second, the lack of a negative genetic correlation between egg size and number suggests that the phenotypic trade-off frequently observed between egg size and number in other organisms may not evolve over the short term via a direct genetic trade-off whereby increases in egg size are automatically accompanied by decreased fecundity. Finally, total reproductive allocation may not evolve independently of egg size as commonly assumed.

Drosophila melanogaster↗
PubMed2004

End-of-cycle bone quality in white- and brown-egg laying hens.

Broken and weak bones of laying hens are major welfare concerns in the table egg industry. Bone quality at the end of lay of brown- (Shaver 579) and white-(Shaver 2000) egg strains were compared. Prior to the start of the experiment, the hens had been housed in laying hen cages (2/cage). At 423 d of age (60 wk + 3 d), 24 hens of each strain were selected and individually caged, and egg production records were kept until 462 d of age (the end of 65 wk) for a total of 39 d. Egg quality analysis was undertaken during wk 65 of age. Hens were killed at 66 wk of age (463 d), and carcass and reproductive morphology traits were measured. Femur and humerus mineral density were measured using quantitative computed tomography, and breaking strength was measured by an Instron Materials Tester. The white-egg strain produced 3.7% more marketable eggs during the experiment due to a 0.3 d shorter mean pause length in egg production. Eggs from the brown strain were 3.4% heavier, had 4.0% more eggshell, and had a higher specific gravity than the white strain eggs (1.077 and 1.072, respectively). Final BW was 330 g greater in the brown-egg strain. Total bone density of the femur was not different between the 2 strains but was greater in the humerus of the brown-egg layers. Total femur and humerus bone areas were greater in the brown strain than the white-egg strain. Bone breaking strengths of the brown-egg strain were greater by 22% (femur) and 18% (humerus) than in the white-egg strain hens. These results indicate that this brown-egg strain may be more resistant to weak and broken bones at the end of production than the white-egg strain.

Aging↗
PubMed2005

Oviposition pattern, egg weight, fertility, and hatchability of young and old broiler breeders.

Two experiments were conducted to investigate egg weight, fertility, hatchability, and embryonic mortality in relation to time of oviposition of young and old broiler breeder flocks. In experiment 1, eggs were collected from 2 flocks (34 and 59 wk) for 2 d at hourly intervals between 0700 and 1900 h. Most eggs were laid between 0700 and 1300 h, but eggs were laid later in the day by the old flock. Weights of early laid (C1) eggs were significantly greater than middle laid (Cs) and the late laid (Ct) eggs in the young flock, whereas late laid eggs (Ct) were significantly smaller than early laid (C1) and middle laid (Cs) eggs in the old flock. In experiment 2, eggs from experiment 1 were categorized as early laid first-in-sequence (C1) eggs (0700 to 0800 h), the mid-sequence (Cs) eggs (0900 to 1200 h), and the late laid terminal-in-sequence (Ct) eggs (1300 to 1700 h). These eggs were incubated to determine fertility, hatchability, and stage of embryonic mortality relative to oviposition time and flock age. Fertility declined with flock age, but there were no differences due to time of oviposition. There were no differences in hatchability of fertile eggs or embryonic mortality relative to time of oviposition (sequence position) or flock age. These results suggested that although there were differences in egg weight among eggs at different times of the day (different sequence positions), there were no differences in fertility, fertile hatchability, or embryonic mortality in naturally mated broiler breeders.

Aging↗
PubMed2006

Studies on the effect of supplementing boar semen cryopreservation media with different avian egg yolk types on in vitro post-thaw sperm quality.

Fertility after insemination of cryopreserved boar semen is currently below that of fresh semen. In an attempt to improve the post-thaw motility and acrosome integrity of boar sperm, semen was frozen using an adapted Westendorf method in which the chicken egg yolk was replaced by either duck or quail egg yolk. The different composition of the yolk types, particularly the amount of cholesterol, fatty acids and phospholipids, were thought to potentially afford a greater level of protection to sperm against damage during freezing and thawing. Sperm frozen in medium containing chicken egg yolk displayed higher motility immediately after thawing, but there was no difference in the motility of sperm frozen with different types of egg yolk 3 or 6 h after thawing and maintenance at 37 degrees C. Sperm frozen in media containing chicken or duck egg yolk had a higher proportion of intact acrosomes immediately after thawing than sperm frozen in medium containing quail egg yolk, but 6 h after thawing and maintenance at 37 degrees C the sperm that had been frozen in medium containing chicken egg yolk had a higher proportion of intact acrosomes than the sperm frozen in media containing duck or quail egg yolk. Analysis of the composition of the different yolk types showed that the basic components of the yolks were similar, but the ratios of fatty acids and phospholipid classes differed. Duck egg yolk had more monounsaturated fatty acids (MUFA) than chicken egg yolk, which had more MUFA than quail egg yolk. Duck egg yolk contained more phosphotidylinositol (PI) than chicken or quail egg yolks and quail egg yolk contained more phosphotidylserine than either chicken or duck egg yolks. The differences in post-thaw motility and acrosome integrity of boar sperm when frozen in media containing the different types of egg yolk may be due to the variation in composition.

Acrosome↗
PubMed2003

Liquid egg as an alternative protein source in calf milk replacers.

The use of alternative proteins in milk replacer has been evaluated for their ability to decrease the cost of milk replacers without negatively impacting performance of the calf. Three studies were conducted to evaluate the performance of calves fed milk replacer utilizing liquid egg as an alternative protein and to determine the optimal concentration of liquid egg to include in milk replacers. Calves in trials 1 and 2 were assigned to a control diet of all milk protein replacer (MILK) or a diet formulated to contain 5% of the diet (13.5% of the protein) from liquid egg (5% EGG). Calves in trial 3 were assigned to one of four diets: the control (MILK) and 5% EGG diets fed in trials 1 and 2, or diets formulated to contain either 10 or 15% of the diet (27 or 40.5% of the protein) from liquid egg (10% EGG, 15% EGG). For all experiments, milk replacers were formulated to contain 20% protein, 20% fat and were fed at 454 g/d reconstituted to 12% DM. Production of the diets containing egg protein utilized breaker eggs that were pasteurized during manufacturing. Holstein bull calves (n = 44 for experiment 1, n = 38 for experiment 2, and n = 120 for experiment 3), were purchased from an area sale barn. Calves were housed in individual hutches with water available free choice starting on d 0. A commercially available calf starter was offered free choice beginning on d 7 for experiments 1 and 2 and on d 1 for experiment 3. Feed intake, scour scores, and antibiotic treatments were recorded daily. For experiment 1, calves fed 5% EGG had greater weight gains than calves fed MILK. No differences in average daily feed intake were observed. For experiment 2, weight gains tended to be lower with 5% EGG, whereas feed intakes and gain to feed ratios were similar between calves fed MILK or 5% EGG. For experiment 3, as the amount of egg in the diet increased, weight gain decreased in a linear fashion during the milk replacer feeding period, but the decrease in gain was significant only with the 15% EGG diet. These results indicate that egg is an effective alternative protein source to milk protein in calf milk replacers when fed at levels up to 10% of the diet in a conventional feeding program of 0.45 kg per head per day.

Animal Feed↗
PubMed2000

Factors influencing inactivation of Salmonella enteritidis in hard-cooked eggs.

The inside of a hen's egg, once considered sterile, is now known to occasionally harbor Salmonella Enteritidis. At least two recent outbreaks of salmonellosis in which Salmonella Enteritidis PT34 was involved have been associated with hard-cooked eggs. This study was undertaken to compare D56 degrees C values of Salmonella Senftenberg 775W and six strains of Salmonella Enteritidis isolated from outbreaks associated with eggs. D56 degrees C values for Salmonella Enteritidis in liquid egg yolk ranged from 5.14 to 7.39 min; the D56 degrees C value for Salmonella Senftenberg was 19.96 min. The two PT34 strains from outbreaks associated with hard-cooked eggs did not exhibit significantly higher resistance to heat compared with two PT4 strains and one strain each of PT8 and PT13a. A PT4 strain and a PT34 strain of Salmonella Enteritidis were separately inoculated (10(7) to 10(8) CFU) into the yolk of medium and extra large shell eggs at 10 and 21 degrees C, and survival was monitored using two cooking methods: (i) placing eggs in water at 23 degrees C, heating to 100 degrees C, removing from heat, and holding for 15 min (American Egg Board method) and (ii) placing eggs in water at 100 degrees C, then holding for 15 min at this temperature. Within the 15-min holding periods, inactivation was more rapid using the method recommended by the American Egg Board compared with method 2. Within each cooking method, inactivation was most rapid in medium eggs initially at 21 degrees C. The PT4 strain survived in yolk of extra large eggs initially at 10 degrees C when eggs were held in boiling water 9 min using method 2. The final temperature of the yolk in these eggs was 62.3 +/- 2 degrees C. Of the two methods evaluated for hard cooking eggs, the American Egg Board method is clearly most effective in killing Salmonella Enteritidis in the yolk.

Animals↗
PubMed2004

Effects of supplementary iodine on the performance and egg traits of laying hens.

1. This experiment was carried out to determine the effects of dietary iodine supplementation on the performance and egg traits of laying hens. A total of 600 SHSY type brown layers aged 21 weeks of age were chosen at random from a large flock. They were randomly distributed into 30 pens at 20 hens per pen. Each treatment comprised 6 replicates of 20 layers in groups of 5 birds. The diets were supplemented with 0, 3, 6, 12 and 24 mg/kg iodine as calcium iodate. The experimental period lasted 30 weeks. 2. There were no significant differences among the groups in body weight, food consumption, egg production, food consumption per kg eggs, eggshell index, eggshell breaking strength, shell thickness or egg yolk index. 3. Supplementation of the diet with 12 mg/kg iodine increased food consumption per dozen eggs compared to the groups fed on diets supplemented with 0 and 6 mg/kg iodine. 4. Egg weight was less in groups fed on diets supplemented with 12 and 24 mg/kg iodine than in the group receiving no iodine supplementation. 5. Iodine supplementation to provide 12 and 24 mg/kg reduced egg albumen index and egg Haugh units. 6. There were no significant differences among the groups in egg cholesterol and egg yolk cholesterol contents. 7. The iodine concentrations in egg yolk, egg albumen and whole egg increased with increased iodine supplementation. 8. As a result, the 3 and 6 mg/kg iodine supplementation of diet could be used to enrich the eggs with iodine without any adverse effect on performance and egg traits.

Animal Feed↗
PubMed2005

Effect of irradiating shell eggs on quality attributes and functional properties of yolk and white.

Shell eggs were irradiated and the physico-chemical, and functional properties of egg yolk and white were determined. The color of egg yolk was not affected, but the viscosity of egg white was dramatically lowered and became watery by irradiation. The foam capacity and foam stability of egg white were significantly decreased due to protein oxidation by irradiation. However, the texture characteristics of egg white were not changed by irradiation, indicating that irradiation may not alter the thermal characteristics of egg white proteins. Sulfur volatiles were generated by irradiation but disappeared during storage under aerobic conditions. Because egg white became watery, irradiation may not be advisable for table eggs but may be useful for pasteurizing liquid egg white or liquid whole egg without significant deterioration of their quality and functionality. In particular, the dramatic decrease in the viscosity of egg white by irradiation will improve flow of liquid egg white or liquid whole egg, which could be highly useful for egg processing.

Animals↗
PubMed1994

Artificial parthenogenesis in starfish eggs: behavior of nuclei and chromosomes resulting in tetraploidy of parthenogenotes produced by the suppression of polar body extrusion.

Artificial parthenogenesis in starfish requires the activation of oocytes and the suppression of the polar body (PB) extrusion. To induce parthenogenesis we have employed a combination of calcium ionophore A23187 for activating oocytes and cytochalasin B (CB) for the suppression of PB extrusions. The treatment of activated oocytes with CB during meiosis I produced eggs lacking polar bodies, i.e., during meiosis I produced eggs lacking polar bodies, i.e., 0pb eggs, and treatment during meiosis II induced eggs bearing the first PB only, i.e., 1pb eggs. About 90% of both 0pb and 1pb eggs developed parthenogenetically with strong synchrony of cell division among eggs. After meiotic chromosomes in CB-treated oocytes separated finally into monads, they came together to form a single nucleus. The nucleus was found to be tetraploid in the 0pb eggs and diploid in the 1pb eggs. Regardless of the difference in ploidy, both 0pb and 1pb eggs developed as tetraploid embryos. Observations of the behavior of meiotic chromosomes and nuclei revealed that in the 0pb eggs, the first round of chromosomal replication was followed by the first cleavage, as in normally fertilized eggs. In the 1pb eggs, on the other hand, two rounds of chromosomal replication were found to precede the first cleavage, indicating the occurrence of one (first) round of chromosomal replication that is not accompanied with cytokinesis. In the first round of mitosis, a bipolar spindle did not appear, but only a half spindle was formed, resulting in the failure of both karyokinesis and cytokinesis. Thus, both types of parthenogenetic eggs became tetraploid before the first cleavage. At the first cleavage, both types of eggs formed a bipolar spindle and divided into a pair of blastomeres. Based on these observations, we suggest that the meiotic centrosomes remaining in these eggs by the failure of PB extrusion are diverted into mitosis-organizing centers in the mitotic spindle, and this results in parthenogenetic development.

Animals↗
PubMed2003

Function of a sea urchin egg Src family kinase in initiating Ca2+ release at fertilization.

Egg activation at fertilization requires the release of Ca(2+) from the egg's endoplasmic reticulum, and recent evidence has indicated that a Src family kinase (SFK) may function in initiating this signaling pathway in echinoderm eggs. Here, we identify and characterize a SFK from the sea urchin Strongylocentrotus purpuratus, SpSFK1. SpSFK1 RNA is present in eggs, and an antibody made against a SpSFK1 peptide recognizes an approximately 58-kDa egg membrane-associated protein in eggs of S. purpuratus as well as another sea urchin Lytechinus variegatus. Injection of both species of sea urchin eggs with dominant-interfering Src homology 2 domains of SpSFK1 delays and reduces the release of Ca(2+) at fertilization. Injection of an antibody against SpSFK1 into S. purpuratus eggs also causes a small increase in the delay between sperm-egg fusion and Ca(2+) release. In contrast, when injected into eggs of L. variegatus, this same antibody has a dramatic stimulatory effect: it causes PLCgamma-dependent Ca(2+) release like that occurring at fertilization. Correspondingly, in lysates of L. variegatus eggs, but not S. purpuratus eggs, the antibody stimulates SFK activity. Injection of L. variegatus eggs with another antibody that recognizes the L. variegatus egg SFK also causes PLCgamma-dependent Ca(2+) release like that at fertilization. These results indicate that activation of a Src family kinase present in sea urchin eggs is necessary to cause Ca(2+) release at fertilization and is capable of stimulating Ca(2+) release in the unfertilized egg via PLCgamma, as at fertilization.

Amino Acid Sequence↗
PubMed2002

Preservation of rainbow trout (Oncorhynchus mykiss) eyed eggs using a perfluorochemical as an oxygen carrier.

The objective of this study was to maintain the viability of chilled rainbow trout (Oncorhynchus mykiss) eyed eggs during storage using oxygenated perfluorochemical (PFC). Three trials were conducted using eggs at 161, 180 or 217 degree days (days from fertilization x incubation temperature in degrees C). A separate trial was conducted for 147 degree day eggs that were not at the eyed stage. For each trial, eggs were stored in a moisture-saturated atmosphere at 1 degrees C in PFC, water, and 1:1 combinations of PFC and PBS, PFC and 0.3 M glucose, PFC and mineral oil, or PFC and water. The PFC was oxygenated before each trial and all media were oxygenated at weekly intervals during the storage period. Eggs from each trial were also incubated without storage to provide Day 0 results. After 3 and 5 weeks of storage, eggs from each medium were incubated at 10 degrees C until hatch. Hatching percentage was expressed as a percentage of Day 0 results. The percentage of normal alevins that hatched was also determined. There were interactions (P < 0.01) between stage of development and treatment for hatching percentage after 3 and 5 weeks of storage. After 3 weeks of storage, eggs stored at 161, 180, or 217 degree days without PFC had hatching rates of 0-14.3% but eggs stored in any medium with PFC had hatching percentages from 75.1 to 106.4% of Day 0 values. After 5 weeks of storage, eggs stored at 161 degree days in PFC plus PBS or PFC plus water, and eggs stored at 217 degree days in PFC or PFC plus water, had higher (P < 0.05) hatching percentages than eggs stored in any of the other media. Eggs stored at 161 degree days for 5 weeks in PFC and water had a higher (P < 0.05) percentage of normal alevins hatching than eggs stored in PFC and PBS. Because of their early developmental stage, eggs stored at 147 degree days had low hatching percentages, except eggs stored for 3 weeks in PFC or PFC plus PBS. Chilling eyed eggs of rainbow trout to 1 degrees C and storing them in water with PFC as an oxygen carrier can preserve their viability for 5 weeks.

Animals↗