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PubMed1985

The effect of pelleting the layer ration on egg size in early-housed brown-egg-type layers.

Harco Sex-Link pullets (n = 360) were reared in cages and given a 15% protein grower ration. At 17 weeks of age, half the birds were transferred to laying cages and the photoperiod was increased to 13 hr for the first week and to 15 hr thereafter. The remaining birds were continued in the growing facility on 8 hr of light until 19 weeks when lights were increased to 13 hr daily. These birds were transferred to the laying cages at 20 weeks of age where they received 15 hr of light. At 2% production, all birds were fed a 17% protein layer diet in either a mash or pelleted form. Neither egg production nor feed efficiency was affected by age at housing or the physical form of the ration. Early-lighted pullets produced a greater percentage of small and medium-sized eggs. Egg size distribution was not affected by the physical form of the ration

Animal Feed↗

PubMed1994

Natural history of Schistosoma mansoni infection in mice: egg production, egg passage in the feces, and contribution of host and parasite death to changes in worm numbers.

Mice, C57Bl/6N (B6) and BALB/cAnN (BALB), infected with Schistosoma mansoni were examined 8-26 weeks postinfection (PI) to estimate the fecundity of the worms and the contribution of death of worms and the death of heavily infected mice to the decrease in worm numbers in chronic infections. Portal worms were recovered by perfusion and the lungs were examined for parasites shunted from the portal circulation. Animals that died were more heavily infected than those that survived. Between eight and 12 weeks PI, this loss of worms resulted in a net decrease of approximately 19% of worm pairs in surviving BALB mice, but of only 4% in B6 mice. Loss of portal worms to the lungs after the eighth week of infection was 9-13% of portal worms in BALB mice and 3-4% in B6 mice. The estimated rates of egg production by S. mansoni decreased slightly with time in both strains of mice. At 12 and 20 weeks PI, tissue eggs per worm pair and eggs passed in the feces per worm pair often decreased as the intensity of infection increased. We do not consider the loss of worms in the murine host relevant to most infections in humans because of the high intensity of infection relative to body size in mice and the high frequency of severe portal obstruction in murine infections.

Animals↗

PubMed1987

Scanning electron microscopy of early dinosaur egg shell structure: a comparison with other rigid sauropsid eggs.

Fossil eggs attributable to dinosaur (probably prosauropod) parentage that have been recovered from the early Jurassic Elliot Formation sediments at the Rooidraai locality possess shells that are similar to those of birds and crocodilians, and distinctly unlike those of chelonians and gekkonids. The preserved shell is very thin, and distinct mammillary processes are lacking, although the inner surface displays an undulating contour. The absence of these processes may be attributable to the inner portion of the shell having been at least partially decalcified during incubation and not preserved in the fossil state. The shells appear to be composed of broadly wedge-shaped, albeit ill-defined calcareous units, and they are similar to those of birds and other dinosaurs in the pattern of cleavage shown by the tabular calcite crystals of the palisade layer, and in the absence of the dominant horizontal lamellae that characterize crocodilian shells. The differential resemblance of these early Jurassic shells to the eggs of other closely related sauropsid taxa may be pertinent to questions concerning the evolution of egg shell structure within this clade.

Alligators and Crocodiles↗

PubMedDate not supplied

Prevention of egg transmission of Mycoplasma meleagridis by antibiotic treatment of naturally and experimentally infected turkey eggs.

Turkey eggs infected naturally and experimentally and treated with 1 mg of tylosin or gentamicin before incubation produced progeny with less infection with Mycoplasma meleagridis than did infected but untreated eggs. Higher doses of gentamicin eliminated infection, as indicated by an absence of M. meleagridis antibodies in poults tested at 3 weeks and retested at 5 weeks of age. The rate of reduction or elimination of egg transmission was correlated negatively with the incidence of M. meleagridis infection in untreated controls. Hatchability was reduced by gentamicin, especially at doses of 1.75 and 2 mg, whereas tylosin at 1 mg/egg improved hatchability.

Animals↗

PubMed1985

Effect of microwave irradiation (2.45 GHz, CW) on egg weight loss, egg hatchability, and hatchling growth of the Coturnix quail.

Fertile eggs of the Coturnix quail were exposed twice a day for 30 min to 2.45-GHz continuous wave radiation at power densities of 25 or 50 mW cm-2 throughout the 17-day incubation period. Other eggs were exposed to 20 degrees C or 24 degrees C temperatures twice daily. Repeated exposures to 20 degrees C, 24 degrees C, or 25 mW cm-2 did not reduce hatchability. Irradiation at 50 mW cm-2 lowered hatchability, probably as a result of high egg temperatures. Hatchlings that had been irradiated by microwaves as embryos had normal growth rates and no obvious developmental abnormalities.

Abnormalities, Radiation-Induced↗

PubMed1979

Fertilization of hamster eggs in vitro at sperm:egg ratios close to unity.

Hamster epididymal spermatozoa were washed and preincubated at extremely low sperm concentrations (100/ml or less) in a culture medium containing naturally-occurring sperm motility-stimulating substances. These substances were partially purified "sperm motility factor" (SMF) derived from hamster adrenal glands and catecholamines (epinephrine or isoproterenol). After preincubation for three hours, a small number (5 or less) of washed, cumulus-free hamster eggs was added to each sperm suspension. Many of these eggs were undergoing fertilization when examined two to three hours later. Fertilization was accomplished in vitro at sperm:egg ratios approaching 1:1, a situation comparable to that believed to exist in vivo. It appears that this demonstration will considerably enhance the potential of in vitro fertilization studies for providing useful information on mammalian gamete interactions.

Animals↗

PubMed1998

Sperm-egg binding in the sea urchin: a high level of intracellular ATP stabilizes sperm attachment to the egg receptor.

Previous studies have established that a recombinant protein fragment (45A) of the egg receptor for sperm of the sea urchin Strongylocentrotus purpuratus exhibits several characteristics that are consistent with that expected of a receptor. Using a quantitative sperm binding assay with glutathione S-transferase fused to a recombinant protein containing the C-terminal half of the 45A construct immobilized on glutathione beads, it was found that the interaction between sperm and this protein is a kinetically transient event. Sperm binding to the receptor fragment reached a maximum at 20 s after adding sperm in the presence of egg jelly to beads coated with recombinant receptor. In the next 20-120 s, approximately 50-70% of the sperm detached from the beads. Similar phenomena were observed when the kinetics of sperm binding to dejellied, glutaraldehyde-fixed eggs were studied. Because the acrosome reaction, a prelude to binding, is known to be accompanied by a decrease in the ATP level of sperm, we studied the effect of various inhibitors on both sperm detachment and the level of ATP. It was found that the detachment rate increased slightly when respiration inhibitors that blocked ATP production in mitochondria were added. In contrast, the dynein ATPase inhibitor, erythro-9-[3-hydroxynonyl]adenine, which is known to inhibit flagellum motility by blocking ATP utilization, stabilized the binding of sperm to the receptor and allowed maintenance of a high internal ATP level. Immotile, tailless sperm that physically lacked dynein ATPase, and therefore sustained their internal ATP levels, also exhibited stable binding provided that the sperm and beads were physically mixed. These results suggest that the internal ATP level of the sperm controls the stability of its binding to the receptor. The possible mechanism of the detachment and its significance with respect to the overall process of fertilization are discussed.

Adenine↗

PubMed1984

Fertilization acid release in Urechis eggs. I. The nature of the acid and the dependence of acid release and egg activation on external pH.

The amount of fertilization acid produced by eggs of Urechis caupo , monitored by automatically back-titrating egg suspensions with base, depends linearly on the pH of the seawater. Above pH 7.0, at which no acid is released (Paul, M., Dev. Biol. 43, 299-312, 1975), acid release increased approximately 0.34 pmole/egg/0.1 pH unit. Activation (germinal vesicle breakdown) depended on the amount of acid release in natural seawater; it did not occur if eggs released less than 1.5 pmole acid/egg. When fertilization acid is released into HCO-3-free seawater and the pH permitted to decrease, the supernatant can be tested for the presence of a volatile acid, such as CO2, by bubbling with N2 and comparing the increase in pH as volatile acid is driven off with experiments in which HCl or CO2 is substituted for fertilization acid. An increase in pH of less than 0.2 pH units occurred on N2 bubbling when fertilization acid or HCl was used to acidify HCO-3-free seawater compared to an increase of greater than 0.5 pH units when CO2 was used. Therefore, most, if not all, of Urechis fertilization acid is not volatile, and since Paul (1975) showed that it is not a nonvolatile weak acid, it must be H+.

Animals↗

PubMed1990

Structure and development of the egg of the glossiphoniid leech Theromyzon rude: reorganization of the fertilized egg during completion of the first meiotic division.

Reorganization of the fertilized egg during completion of the first meiotic division was studied in the glossiphoniid leech Theromyzon rude. Rotation of the meiotic spindle, presumably as a result of changes in the length and arrangement of astral fibers, allows one of its poles to approach the prospective animal pole (AP), which appears as a differentiated region of the ectoplasm. The peripheral spindle pole is greatly modified during its anchorage to the AP and is dismantled upon emission of the first pole cell. Meanwhile, the central spindle pole is less modified and is reused during the second meiotic division. Redistribution of microvilli, as well as rearrangement of the ectoplasmic actin lattice, lead to remodeling of the egg surface. Emission of the first pole cell is preceded by a contraction wave that seems to arise by condensation of subcortical actin filaments at the equator of the egg. Poleward displacement of this wave causes evagination of the AP and ooplasmic segregation. A cytokinetic contractile ring forms by assembly of cortical actin filaments at the base of the AP evagination. When this process is disturbed by colchicine or cytochalasin B treatment, abortive or ghost pole cells may be formed.

Animals↗

PubMed1991

The egg-shell of Drosophila melanogaster. VI, Structural analysis of the wax layer in laid eggs.

Utilizing freeze-fracturing conventional electron microscopy and scanning electron microscopy methods, a wax layer was identified, sealing the oocyte of Drosophila melanogaster. In mature egg-shells wax forms a hydrophobic layer surrounding the oocyte and lying between, and in very close contact with the vitelline membrane (interiorly) and the crystalline intermediate chorionic layer (exteriorly). In cross-fractured views it is less than 50 A thick whereas in longitudinal fracturing it reveals smooth fracture faces of a multilayered material in the form of hydrophobic areas or plaques (0.5-1 microns in diameter) which are partially overlapping and highly compressed between the vitelline membrane and the innermost chorionic layer. The evidence for this layer being a wax are the facts that a) it is not preserved in conventional fat-extracting electron microscopy methods, b) it directs laterally the fracture planes during freeze-fracturing and reveals smooth fracture faces. Analysis of the structural features of wax in mature egg-shell in various species of Drosophilidae have shown that the wax layer exhibits indistinguishable (among the species) hydrophobic plaques, which have the same size and thickness with Drosophila melanogaster. These data provide structural evidence explaining the physiological resistance of the insect eggs studied, against water loss or water uptake, whenever they are laid on substrates with extreme environmental conditions. In addition, the data demonstrate how an extracellular substance can be organized to perform that function.

Animals↗

PubMed1991

Effect of maitotoxin on sea urchin egg fertilization and on Ca2+ permeabilities of eggs and intracellular stores.

Maitotoxin (MTX), a potent marine toxin involved in ciguatera poisoning, inhibited sea urchin egg fertilization in a dose-dependent manner with an IC50 of 7.5 x 10(-3) MU (mouse-unit)/ml. It did not affect male gametes fertilizing capabilities but provoked exocytosis in female gametes. It induced a K+ loss simultaneously with a Na+ entry into unfertilized eggs and increased the Ca2+ influx at higher concentrations. On isolated cortex preparations, high concentrations of MTX reduced the rate of ATP-dependent Ca2+ accumulation into reticulum compartments and caused a leakage of Ca2+ from a preparation pre-loaded with 45Ca2+. Verapamil (10(-4) M) similarly blocked the increase of egg permeability to Ca2+ and the effect on Ca2+ sequestering into intracellular compartment, induced by MTX. Ion transport perturbations which evolved relatively slowly are probably not the direct cause of fertilization inhibition which could be related to a modification of the plasma membrane of the female gametes by this hydrophilic toxin.

Animals↗

PubMed1981

The role of oligosaccharide in transport of egg yolk riboflavin-binding protein to the egg.

The carbohydrate portion of chicken egg yolk riboflavin-binding protein was examined to determine its role in the biological activity of the protein. Yolk RBP was found to contain 5--6 mannose, five galactose, 12 N-acetylglucosamine and four sialic acid residues. Specific modifications of the oligosaccharide moiety were performed which included removal of sialic acid by mild acid hydrolysis, oxidation of galactose by galactose oxidase, and removal of N-acetylglucosamine and galactose residues by a mixture of glycosidases from Aspergillus niger. All of the modified proteins retained the ability to bind riboflavin although their capacities were lower than that of native yolk RBP. Circular dichroism of the modified yolk RBP samples showed changes in the near ultraviolet, but molar ellipticities in the far ultraviolet displayed only minor variations indicating no gross structural changes. All samples cross-reacted with RBP-specific antiserum. The plasma half-life of 125I-labeled yolk RBP was 62 min. Each of the modified samples was cleared more rapidly from the blood than native yolk RBP. Removal of sialic acid decreased the half-life of yolk RBP by 31%, while the other modifications decreased the half-life by as much as 60%. During a 10-day period following injection of 125I-labeled yolk RBP, 5.9% of the labeled protein was recovered from egg yolk. Relative to native yolk RBP, the transport of asialo-yolk RBP was decreased by 82%. The other modifications resulted in even less transport to the egg, the lowest being glycosidase-treated asialo-yolk RBP which was decreased by over 99%. By comparison of samples with similar clearance times, a positive correlation was made between sialic acid and ovarian transport.

Animals↗

PubMed1982

Serological examination and egg production of progeny of fowl experimentally infected with egg drop syndrome 1976 virus.

Following EDS'76 virus (BC14 virus) infection of breeder chickens by the conjunctival route, vertical transmission occurred in the first week after infection. In the progeny which had been infected with EDS'76 virus by the vertical route, increasing haemagglutination inhibiting (HI) titres to BC14 virus and increasing numbers of birds with HI titres were observed from 3 weeks to 15 weeks of age. Sixty-one per cent of the hens and 77 per cent of the cocks had 2 log HI BC14 virus titres exceeding 4 at an age of 15 weeks. Some birds which han been serologically negative throughout the rearing period, seroconverted between 25 and 28 weeks of age. This phenomenon occurred in hens as well as in cocks. Simulation of stress twice during the laying period by injection of corticosteroid hormone did not increase the number of birds serologically positive to EDS'76 virus. EDS'76 was observed in the group of hens that was vertically infected, since egg production was significantly depressed between 28 and 34 weeks of age. Probably this was mainly the results of a production drop in the hens showing serconversion at 27 or 28 weeks of age. In this group of fowl vertically infected with EDs'76 virus, serologically positive birds appeared to be protected for the greater part to BC14 virus challenge at 50 weeks of age, while negative birds seemed to be fully susceptible. Chicks hatched from eggs collected in the third and fourth week after infection of the dams had maternal antibodies. Fertility and hatchability of apparently normally shelled eggs seemed not to be affected after BC14 virus infection of the dams. Intensive contact with contaminated faeces is probably an indispensable condition for lateral transmission of the virus.

Adenoviridae Infections↗

PubMed1985

"Spiral asters" and cytoplasmic rotation in sea urchin eggs: induction in Strongylocentrotus purpuratus eggs by elevated temperature.

"Spiral asters" composed of swirls of subcortical microtubules were recently described in fertilized eggs of the sea urchin Strongylocentrotus purpuratus. In our study, these structures did not occur at culture temperatures below 16 degrees C. When the culture temperature was elevated, however, "spiral asters" routinely appeared during a susceptible period before mitotic prophase when the sperm aster-diaster normally exists. A massive and protracted rotation of the cytoplasm (excluding an immobile cortex and perinuclear region) began within 1 min of exposure to elevated temperature. Fibrils of the "spiral aster" could be seen within this rotating mass even by bright-field microscopy. The identity of microtubules in these structures was confirmed by indirect immunofluorescence microscopy. A mechanistic association between "spiral aster" formation and cytoplasmic rotation was indicated by the simultaneous inhibitory effects of microtubule and dynein poisons. Inhibitors of microfilaments, however, had no effect. We infer that elevated temperature induces unique changes in the microtubules of the pre-prophase sperm aster-diaster, resulting in cytoplasmic rotation and the spiral configuration of microtubules. Comparative cytological evidence supports the idea that "spiral asters" do not normally occur in fertilized sea urchin eggs. Biogeographic evidence for S. purpuratus indicates that fertilization and development naturally occur below 15 degrees C, hence "spiral asters" in eggs of this species should be regarded as abnormalities induced in the laboratory by unnaturally elevated temperatures.

Animals↗

PubMed1960

Studies on sulfhydryl groups during cell division of sea urchin egg. II. Mass isolation of the egg cortex and change in its--SH groups during cell division.

Masses of cortices of both unfertilized and fertilized sea urchin eggs can be isolated by crushing eggs in hypotonic MaCl(2) (0.1 M) solution. The amount of cortical material in terms of protein-N increases steadily after fertilization until the monaster stage and thereafter remains almost constant until well into the two-cell stage. The amount of bound-SH per protein-N of the egg cortex also increases after fertilization, reaches a maximum value at the amphiaster stage and thereafter decreases rapidly as the cleavage of the cell proceeds.

Animals↗

PubMed1992

Plasmid replication in Xenopus eggs and egg extracts: a 2D gel electrophoretic analysis.

We have examined the replication patterns of ribosomal DNA plasmids in vivo and in vitro using Xenopus eggs. Plasmids carrying different parts of the Xenopus ribosomal DNA sequence were allowed to replicate either in vitro in an egg extract or in vivo after microinjection into unfertilized eggs. The replication intermediates were analyzed by the 2D gel electrophoretic technique of Brewer and Fangman (1), using original or modified electrophoresis conditions. With standard electrophoresis conditions, the patterns obtained for restriction fragments larger than 5 kb were unreliable because of artefactually distorted Y arcs and unrecognizable bubble arcs. Interpretable patterns could nevertheless be obtained using suitably modified electrophoresis parameters. Under these conditions, replication was found to initiate and terminate at multiple, random locations on each plasmid both in vivo and in vitro. However, only one or very few of these potential initiation sites are used during the replication of an individual plasmid molecule. We discuss the possible artefacts and misinterpretations that can result when the 2D electrophoresis parameters are not adapted to the size of the fragment examined. We also discuss the relevance of the random replication mode to the mechanisms and the control of DNA replication in eukaryotes.

Animals↗

PubMed1998

Enzyme responsible for egg envelope (chorion) hardening in fish: purification and partial characterization of two transglutaminases associated with their substrate, unfertilized egg chorion, of the rainbow trout, Oncorhynchus mykiss.

From our previous studies, we have suggested that "egg envelope (chorion) hardening-enzyme" (first proposed by Zotin [J. Embriol. Exp. Morph. 6, 546-568 (1958)]) in the rainbow trout, Oncorhynchus mykiss, is transglutaminase (TGase), and that it coexists with its substrate, the unfertilized egg chorion, and forms epsilon-(gamma-glutamyl)lysine cross-links between the chorion proteins. In the present study, we extracted the TGase activity from the isolated chorions by homogenization with isotonic saline (143 mM NaCl-10 mM Tris.HCl, pH 7.2) and fractionated the extract by Toyopearl HW55S gel filtration with the isotonic saline containing 5 mM CaCl2 and 5 mM 2-mercaptoethanol (2-ME). One peak of TGase activity (P2) was obtained. When the eluates were dialyzed against 5 mM CaCl2/5 mM 2-ME/10 mM Tris.HCl (pH 7.2), another peak of the activity (P1) appeared. P1 TGase activity, which becomes apparent in a medium of low ionic strength, is involved in acceleration of the chorion hardening after egg activation in fresh water, so-called water activation. We purified the two TGases, P1 and P2, by SP-Sepharose, Q-Sepharose, and TSK-gel column chromatography. The molecular mass of the native form of P1 TGase was estimated as 103 kDa by Toyopearl HW55S gel filtration and as 100 kDa by the TSK-gel filtration. SDS-PAGE analysis showed that it consisted of heterogeneous 86- and 76-kDa proteins. However, these proteins closely resembled each other in amino acid composition, which was characterized by high content of Thr, Gly, and Pro residues as compared with P2 TGase. In contrast, the P2 TGase was isolated as a homogeneous 76-kDa protein and characterized by high content of Glx (Glu/Gln) and His residues. Neither of the chorion TGases of rainbow trout, P1 and P2, was similar to the liver-type TGase of red sea bream or the tissue-type TGase of chum salmon in amino acid composition. Examination of susceptibility to various inhibitors, reactivation by CaCl2, pH dependency, and activity of the polymerization of chorion proteins suggested that the P1 and P2 TGases were essentially similar to each other in enzymatic properties.

Animals↗

PubMed2006

Effect of flock age, cessation of egg turning, and turning frequency through the second week of incubation on hatchability of broiler hatching eggs.

Hatching eggs from commercial broiler breeder flocks at 34 and 37 wk of age (young) and at 59 and 61 wk of age (old) were stored for 2 d at 18 degrees C and 75% RH and then subjected to turning frequencies of 24 or 96 times daily up to 8, 10, 12, or 14 d of incubation at standard conditions to determine if an increased turning frequency would facilitate an early cessation of turning. Turning was discontinued after the respective days were completed. Eggs remained in setter trays until combined at 18 d to complete hatching in a single machine. The young flocks exhibited significantly better fertile hatchability, as expected, but there was no overall effect due to differences in cessation of turning from 8 to 14 d of incubation (range 88.9 to 89.2%). However, turning 96 times daily produced significantly better fertile hatchability that was largely due to a significant interaction of flock age and turning frequency; the beneficial effect of increased turning frequency, largely reduced late-embryonic mortality, was more evident in the eggs from the older flocks.

Aging↗