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PubMed2001

Development of the vitellaria of the liver fluke, Fasciola hepatica in the rat host.

The development of the vitellaria of Fasciola hepatica within the liver of its rat host was studied by means of whole-mount stained preparations and transmission electron microscopy, together with light and electron immunocytochemistry using an antibody to vitelline protein B, an eggshell precursor protein synthesized by F. hepatica. No vitelline cells could be identified in flukes recovered from the liver parenchyma, by any of the methods used. In contrast, follicles were present in flukes at the earliest time of recovery from the bile duct, namely, 5 weeks 3 days post-infection. The vitellaria in these flukes formed a row of small follicles on either side of the body. Development of the follicles was rapid: by 6 weeks 3 days, the vitellaria resembled those in the adult fluke and eggs were present in the uterus. Immunolabelling was confined to the shell protein globules in the vitelline cells, confirming the packaging of the eggshell protein within the shell globule clusters.

Animals↗
PubMed2003

Effect of cholecalciferol-enriched hen feed on egg quality.

Eggs are one of the most important sources of vitamin D in the human diet, and their vitamin D content can be further increased by adding more vitamin D to hen feed. To investigate this issue more closely, we performed two feeding experiments. In both, zero egg samples were collected while the hens were fed regular feeds with a vitamin D content of 1720 or 4280 IU/kg. In experiment 1, egg samples were collected 2, 4, 7, 9, 11, 13, 16, 23, and 30 days after beginning the high-cholecalciferol (11 200 IU/kg) feeding period. In experiment 2, samples were collected 2, 4, 6, 8, 13, 28, 56, 84, 112, 140, and 168 days after beginning the high-cholecalciferol (12 000 IU/kg) diet. The egg samples were then assayed for their cholecalciferol content, and some samples, also for the presence of 25-hydroxycholecalciferol by an HPLC method. Further, the vitamin D-fortified eggs were compared with the controls by a sensory evaluation, by conducting fatty acid and functional analyses (emulsion capacity, gel forming capacity, foaming properties) and by measuring eggshell strength. Because vitamin D can be toxic in high doses, we also performed histopathological tests on the hens at the end of experiment 2. The top cholecalciferol contents in egg yolk (ca. 30 microg/100 g) were reached 8-13 days from starting the high-cholecalciferol diet. After 112 days feeding the cholecalciferol content gradually decreased to ca. 22 microg/100 g. When added to eggs as described above, vitamin D did not affect their sensory or functional properties or their fatty acid composition. Moreover, the cholecalciferol levels used in this study appeared not to affect eggshell strength or to be harmful for hens.

Animal Feed↗
PubMed2000

Process of egg formation in the female body cavity and fertilization in male eggs of Phytoseiulus persimilis (Acari: Phytoseiidae).

The process of egg formation in the body cavity of a phytoseiid mite, Phytoseiulus persimilis, was observed to examine fertilization of male eggs. After insemination, one of the ova at the periphery of the ovary began to expand, taking up yolk. Two pronuclei appeared in the expanded egg, located dorsally in the ovary, and yolk granules were formed gradually. After the egg became filled with yolk granules the two pronuclei fused. The egg moved via the narrow entrance at the ventral region into the oviduct, where the eggshell was formed. When the eggshell was complete, and while embryogenesis proceeded, the egg was deposited. In the meantime some ova began to expand sequentially and two joining pronuclei appeared in expanding eggs. The joining pronuclei in the first egg proved male diploidy. This is additional evidence of pseudo-arrhenotoky in this phytoseiid mite species, since the first eggs developed into males.

Animals↗
PubMedDate not supplied

Chlorinated hydrocarbon contamination in osprey eggs and nestlings from the Canadian Great Lakes basin, 1991-1995.

Populations of osprey (Pandion haliaetus) in the Great Lakes basin declined dramatically during the 1950s-1970s due largely to adverse effects of persistent chlorinated hydrocarbons, ingested in their fish prey, on eggshell thickness and adult survival. Nevertheless, these contaminants were not measured in osprey tissues during the decades of decline on the Canadian Great Lakes. Between 1991 and 1995, we monitored recovering osprey populations on the Great Lakes, including Georgian Bay and the St. Marys River area on Lake Huron and the St. Lawrence Islands National Park, as well as at two inland sites within the basin. Current OC levels, even from the most contaminated lakes, were typically lower than those associated with reproductive effects. DDE levels in fresh eggs averaged 1.2-2.9 microg/g, well below the 4.2 microg/g level associated with significant eggshell thinning and shell breakage. Nevertheless, a proportion of eggs from all study areas did exceed this level. PCB levels in eggs seldom exceeded 5 microg/g except in one lake of high breeding density in the Kawartha Lakes inland study area, where the mean sum PCB level was 7.1 microg/g and the maximum concentration measured was 26.5 microg/g. On average, mean reproductive output (0.78-2.75 young per occupied nest) of breeding populations in Great Lakes basin study areas exceeded the threshold of 0.8 young thought necessary to maintain stable populations. We concluded that, although eggs and especially nestling plasma, are useful in reflecting local contaminant levels, ospreys are relatively insensitive, at least at the population level, to health effects of current levels of chlorinated hydrocarbons on the Canadian Great Lakes.

Animals↗
PubMed2002

The origin of lactation as a water source for parchment-shelled eggs.

Available evidence indicates that mammary gland secretions first evolved in synapsids that laid parchment-shelled eggs. Unlike the rigid-shelled eggs of birds and some other sauropsids, parchment-shelled eggs lose water very rapidly when exposed to ambient air of lower vapor pressure, whether due to differences in relative humidity or to differences in temperature. This precludes endothermic incubation of parchment-shelled eggs in an open nest. Synapsids may have avoided egg desiccation by incubating eggs in a pouch, but this would limit maternal activity. Parchment-shelled eggs are able to take up liquid water across the eggshell. I propose that mammary secretion originally evolved as a means of supplying water to eggs, and as such was essential to the evolution of endothermy among the egg-laying cynodonts that were ancestral to mammals. It is possible that synapsid eggs, like parchment-shelled squamate eggs, were also capable of uptake of some nutrients, such as sodium and ionic calcium. Living monotremes still produce parchment-shelled eggs. The porous eggshell and bilaminar yolk sac membrane of these eggs permit substantial uptake of uterine secretions during the intrauterine period, and might also facilitate uptake of mammary secretions during egg incubation. In its simplest form, mammary secretion may be an ancient trait of egg-laying synapsids, having had an important role long before milk became obligatory for suckling young.

Animals↗
PubMed1999

The effect of pentosan polysulphate on bone healing of rat cranial defects.

The purpose of the study was to determine the efficacy of pentosan polysulphate, used in combination with guided bone regeneration on rat skull defects. The study was conducted on 45 adult Wistar rats. On each animal two symmetrical 6 mm wide, full-thickness, skull defects were created in the parietal regions. The right defect was chosen as the experimental site and the left one was left empty to provide a control. Each experimental site was covered by an inner and outer polytetrafluoroethylene membrane. The 45 rats were divided into 3 groups: in group I (n = 15), carboxymethyl cellulose, used as a delivery vehicle, was injected between the two membranes; in group II (n = 15), 1 mg of pentosan polysulfate was added to the carboxymethyl cellulose vehicle; in group III (n = 15), purified micronized eggshell powder was added to the mixture of pentosan polysulfate and carboxymethyl cellulose between the two membranes. In each group, the animals were sacrificed at 42 days. The harvested specimens were processed for contact radiography and standard histological examination. The results were assessed by a Fisher's exact test. All animals, except one, healed uneventfully. In group I, partial bone healing was observed in 14 out of 15 animals. In group II, partial bone healing was observed in 13 out of 15 animals, and complete bone healing in 1 out of 15 cases. In group III, partial resorption of the eggshell implant was observed with a partial bone healing in only 2 cases (P < 0.001). In conclusion, significant bone regeneration was observed with the membranes alone. The use of pentosane polysulphate did not result in additional bone gain. The use of particulate material as a space maintainer is also questionable.

Absorbable Implants↗
PubMed1997

Secretion of a novel, developmentally regulated fatty acid-binding protein into the perivitelline fluid of the parasitic nematode, Ascaris suum.

Early development of the parasitic nematode, Ascaris suum, occurs inside a highly resistant eggshell, and the developing larva is bathed in perivitelline fluid. Two-dimensional gel analysis of perivitelline fluid from infective larvae reveals seven major proteins; a cDNA encoding one of these, As-p18, has been cloned, sequenced, and protein expressed in Escherichia coli. The predicted amino acid sequence of As-p18 exhibits similarities to the intracellular lipid-binding protein (iLBP) family including retinoid- and fatty acid-binding proteins (FABP). As-p18 is unusual in that it possesses a hydrophobic leader that is not present in the mature protein, the developmental regulation of its expression, and in terms of its predicted structure. Recombinant As-p18 is a functional FABP with a high affinity for both a fluorescent fatty acid analog (11(((5-(dimethylamino)-1-naphthalenyl)sulfonyl)amino) undecanoic acid) and oleic acid, but not retinol. Circular dichroism of rAs-p18 reveals a high beta-sheet content (62%), which is consistent with secondary structure for the protein predicted from sequence algorithms, and the structure of iLBPs. Unusual features are apparent in a structural model of As-p18 generated from existing crystal structures of iLBPs. As-p18 is not found in unembryonated eggs, begins to be synthesized at about day 3 of development, reaches a maximal concentration with the formation of the first-stage larva and remains abundant in the perivitelline fluid of the second-stage larva. Since As-p18 is not present in the post-infective third-stage larva or adult worm tissues, it appears to be exclusive to the egg. Surprisingly, however, Northern blot analysis yields mRNA for As-p18 not only in the early larval stages, but also the unembryonated egg, third-stage larvae, and ovaries of adult worms, even though the protein is not detectable from any of those sources. As-p18 may play a role in sequestering potentially toxic fatty acids and their peroxidation products, or it may be involved in the maintenance of the impermeable lipid layer of the eggshell.

Amino Acid Sequence↗
PubMed1995

Calcium solubilization and retention in the gastrointestinal tract in chicks (Gallus domesticus) as a function of gastric acid secretion inhibition and of calcium carbonate particle size.

In chicks, immature pullets and laying hens, the inhibition of gastric acid secretion by omeprazole, an H+,K(+)-transporting ATPase (EC 3.6.1.36) inhibitor, greatly increased proventricular and gizzard pH values. Consequently, gizzard soluble Ca concentration deceased and the insoluble Ca fraction increased. Inhibition of acid secretion increased duodenal pH values in immature pullets and laying hens but not in chicks. Duodenal soluble and ionic Ca concentrations were lowered by gastric acid inhibition in chicks and to a larger extent in immature pullets and laying hens. The use of Ca of coarse particle size increased the gizzard insoluble Ca fraction in chicks and pullets. However, it did not influence its soluble Ca fraction in chicks but tended to reinforce the negative effect of omeprazole on soluble Ca in the gizzard and duodenum of chicks and laying hens. Coarse particles of Ca led to an increase in gizzard and duodenal soluble Ca at the end of eggshell calcification in laying hens. An enhancement in the level of Ca in the diet from 10 to 36 g/kg increased gizzard soluble Ca and duodenal soluble and ionic Ca concentrations in immature and adult hens. Intestinal Ca retention and bone mineralization was unaffected by gastric acid inhibition in chicks but were largely diminished by the use of coarse particles of Ca. Gastric acid inhibition was associated in laying hens with decreased Ca retention to a small extent and with reduced eggshell quality. These observations confirm that gastric acid secretion is of importance for CaCO3 solubilization but question its role as a prerequisite for intestinal Ca retention in chicks and even in hens fed on a high Ca diet.

Animals↗
PubMed2001

Correlation between shell colour and ultrastructure in pheasant eggs.

1. The histochemistry and ultrastructure of pheasant eggs were compared on the basis of blue or brown shell colour. 2. Differences in lectin histochemistry of the outer shell membrane calcification surface indicate a biochemical disruption of the calcification sites in blue eggs. 3. Significant differences were observed in all aspects of eggshell ultrastructure with blue eggs having thinner shells with structural defects. 4. Poor hatchability of blue eggs may reflect high rates of weight loss associated with a defective eggshell.

Animals↗
PubMed2002

Re-evaluation of calcium and phosphorus requirements in aged laying hens.

1. A series of 5 trials was conducted with 401- to 650-d-old Lohmann, Yafa (local breed with brown eggshells) and Yarkon (local breed with white eggshells) hens fed for 56 to 84 d with diets containing 25 to 50 g/kg calcium (Ca) and 4.5 to 7.6 g/kg phosphorus (P). 2. Increasing dietary Ca from 24-25 to 36-40 g/kg improved egg production, shell weight (SW) and shell thickness (ST), and decreased mortality. 3. Increasing dietary Ca to 48 to 50 g/kg did not affect egg production but increased SW and/or ST. In one out of the 4 trials, this effect was not significant, most likely because of the high shell quality of the eggs from the Yafa hens used for this trial. 4. Dietary P content of 4.5 g/kg (1.0 g/kg added inorganic P) appears to be sufficient for maintaining egg production and shell quality in aged laying hen given 36 to 40 g/kg Ca. 5. Increasing dietary Ca above 40 g/kg may require a higher dietary P content.

Aging↗
PubMed1991

Gordon memorial lecture. Physics and physiology of incubation.

1. The earliest mention of artificial incubation occurs in Aristotle's Historia Animalium written in the 4th century BC. A brief survey of the history of incubation is given from that time to the present. 2. Artificial incubation is also practised by birds belonging to the family of the Megapodes: the Brush Turkey and the Mallee Fowl build a mound and maintain the required temperature of the eggs laid in it. 3. The importance of functional eggshell porosity and incubator ventilation rate for maintaining optimal gas tensions in the embryonic medium (the gas space below the shell) is discussed. 4. Among the early scientific studies (reviewed by Landauer, Lundy, Freeman) particular attention is paid to Barott's (1937) systematic work on temperature, relative humidity and oxygen concentration. 5. The requirements of the embryo with regard to temperature, humidity and gaseous environment are defined. The importance of using gas tensions instead of gas concentrations is once again emphasised. 6. The problems of incubation at high altitude are explained and a successful method for hatching eggs at any terrestrial altitude is described. 7. Although hens can be selected for the functional porosity of their eggs, the procedure does not offer any worthwhile advantages. 8. If functional eggshell porosity and embryonic oxygen uptake are known, then optimal incubator ventilation rate can be predicted when a given optimum gas space oxygen tension is assumed.

Altitude↗
PubMed1999

Effects of drilling holes into the air cell of incubated goose eggs on distribution of oxygen partial pressures under the shell.

The purpose of this work was to measure changes in oxygen pressure in the air cell and under the eggshell (P(A)O2) of pre-pipping goose eggs before and after drilling holes into the air cell. Drilling a 0.6 mm (diameter of 0.9 mm) hole into the air cell caused an increase in air cell P(A)O2 of about 10 Torr. The rate of increase attenuated as hole area increased and reached about 21 Torr when the drilled area was 8.5 mm2. The P(A)O2 of intact eggs was not equally distributed under the shell. It was high in the air cell area (108 Torr) and decreased towards the pointed end (86 Torr). The increase in P(A)O2 after drilling a 4.9 mm2 hole was high in the air cell (18 Torr) and decreased with distance, becoming non-significant at the pointed end. The significant increase in P(A)O2 after drilling was limited to a distance of up to 38 mm along the shell from the edge of the air cell. This indicates that lateral diffusion in the shell membranes under the shell is limited. Drilling a hole of 3.5 to 4.9 mm2 was enough to increase air cell P(A)O2 in most of the eggs above the critical value of 100 Torr for hatching success. The increase in P(A)O2 was limited to about half the area of the shell and the average increase in P(A)O2 was 6.3 Torr (equivalent to a 0.9% increase in ambient O2). However, the blood perfusing chorioallantoic areas further away from the air cell edge may not be fully saturated with O2 and may not be sufficient to compensate fully for the low O2 availability caused by low eggshell conductance.

Animals↗
PubMed1984

[15N-labelled lysine in colostomized laying hens. 4. Incorporation of 15N-lysine into various amino acids of egg yolk and white].

Each of three colostomized laying hens received per os 0.2% L-Lysine with 48 atom-% 15N-excess (15N') labelled in alpha-position in addition to a pelleted laying hen ration of 120 g over a period of 4 days. On the following 4 days they received equal amounts of unlabelled lysine. The eggs laid during the 8 days of the experiment were separated into the white of egg, the yolk and the eggshell, and the to and heavy nitrogen in the individual fractions were determined. Above that, 17 amino acids and their atom-%15N' were determined in the 19 samples of the white and yolk of egg. Of the total 15N' from the lysine fed in the 4 days, 10.1% were found in the yolk, 10.5% in the white of egg and 1.1% in the eggshells of the eggs laid during the 8 days of the experiment. 85% of the total amino acid-15N' of the yolk and 86% of the white of egg detected to be lysine-15N'. The 15N'-amount of the other 16 amino acids was mainly concentrated in the two acid and basic amino acids. Approximately 50% of the non-lysine 15N' in the egg are contained in aspartic acid, glutamic acid, histidine and arginine. A very low incorporation of the labelled lysine only could be detected in the aromatic and sulphur-containing amino acids from both the yolk and the white of egg. 43% of the 15N' was detected in the 10 essential and semi-essential (except lysine) and 57% in the 6 non-essential amino acids of the yolk and 52% and 48% resp. of the white of egg. One can summarize that the incorporation of 15N' into the egg shows the same development as that of the labelled amino acids of the wheat protein and that 15% of the lysine-15N' could be detected in the 16 other amino acids.

Amino Acids↗
PubMed2001

Stability of dietary ascorbic acid and the effect of supplementation on reproductive performance of broiler breeder chickens.

1. The purpose of the study was to determine the stability of dietary ascorbic acid and the reproductive responses of broiler breeder chickens to supplemental 75 mg ascorbic acid/kg diet. 2. Six breeder flocks of 13,000 birds each were studied. Egg production, eggshell porosity, fertility, hatchability and plasma ascorbic acid were measured. 3. Storage of the diets under dry heat resulted in a linear decrease in ascorbic acid content and the rate of decline was 5-fold higher in the supplemented diet. 4. Differences were not detected between treatments in egg production, egg weight, eggshell porosity, fertility, hatchability or plasma ascorbic acid. 5. The results did not provide evidence of a beneficial reproductive response to the inclusion of ascorbic acid in commercial broiler breeder diets.

Animals↗
PubMed2002

Drosophila minichromosome maintenance 6 is required for chorion gene amplification and genomic replication.

Duplication of the eukaryotic genome initiates from multiple origins of DNA replication whose activity is coordinated with the cell cycle. We have been studying the origins of DNA replication that control amplification of eggshell (chorion) genes during Drosophila oogenesis. Mutation of genes required for amplification results in a thin eggshell phenotype, allowing a genetic dissection of origin regulation. Herein, we show that one mutation corresponds to a subunit of the minichromosome maintenance (MCM) complex of proteins, MCM6. The binding of the MCM complex to origins in G1 as part of a prereplicative complex is critical for the cell cycle regulation of origin licensing. We find that MCM6 associates with other MCM subunits during amplification. These results suggest that chorion origins are bound by an amplification complex that contains MCM proteins and therefore resembles the prereplicative complex. Lethal alleles of MCM6 reveal it is essential for mitotic cycles and endocycles, and suggest that its function is mediated by ATP. We discuss the implications of these findings for the role of MCMs in the coordination of DNA replication during the cell cycle.

Amino Acid Sequence↗
PubMed2002

Genetic control of cuticle formation during embryonic development of Drosophila melanogaster.

The embryonic cuticle of Drosophila melanogaster is deposited by the epidermal epithelium during stage 16 of development. This tough, waterproof layer is essential for maintaining the structural integrity of the larval body. We have characterized mutations in a set of genes required for proper deposition and/or morphogenesis of the cuticle. Zygotic disruption of any one of these genes results in embryonic lethality. Mutant embryos are hyperactive within the eggshell, resulting in a high proportion reversed within the eggshell (the "retroactive" phenotype), and all show poor cuticle integrity when embryos are mechanically devitellinized. This last property results in embryonic cuticle preparations that appear grossly inflated compared to wild-type cuticles (the "blimp" phenotype). We find that one of these genes, krotzkopf verkehrt (kkv), encodes the Drosophila chitin synthase enzyme and that a closely linked gene, knickkopf (knk), encodes a novel protein that shows genetic interaction with the Drosophila E-cadherin, shotgun. We also demonstrate that two other known mutants, grainy head (grh) and retroactive (rtv), show the blimp phenotype when devitellinized, and we describe a new mutation, called zeppelin (zep), that shows the blimp phenotype but does not produce defects in the head cuticle as the other mutations do.

Amino Acid Sequence↗
PubMed1991

Aedes taeniorhynchus (Diptera: Culicidae) oviposition patterns in a Florida mangrove forest.

The association of Aedes taeniorhynchus eggs and several variables was studied in a Florida mangrove forest. Eggs were limited to stands of red mangrove (Rhizophora mangle L.) that were embedded within a black mangrove (Avicennia germinans L.) forest. The occurrence of eggs was related significantly to elevation and the amount of detritus. Field and laboratory studies indicated that grazing on black mangrove detritus by the snail Melampus coffeus L. may have limited detritus accumulation and soil organic content, thus restricting mosquito oviposition to the red mangrove stands. Eggshells were concentrated in the same habitat as eggs, suggesting that eggshells may be used to identify oviposition patterns.

Aedes↗
PubMed1999

Chorion formation and ultrastructure of the egg of the cat flea (Siphonaptera: Pulicidae).

Oocyte development in adult female cat fleas, Ctenocephalides felis (Bouché), was studied by light and electron microscopy to determine the formation and ultrastructural morphology of the eggshell. As oocytes develop, somatic follicle cells from the lining of the ovariole migrate around the oocytes. The follicle cells produce electron-dense granules that form the vitelline membrane around the developing oocyte. Subsequently, electron-lucent granules containing an electron-dense core (precursors of the chorion) are produced from the rough endoplasmic reticulum that appear as dilated and clear linear clefts in the cytoplasm of the follicle cells. Exocytosis and coalescence of the granules around the oocyte as the follicle cells disintegrate give rise to the chorion. The chorion was found to consist of 4 distinct layers. The external surface of the egg shell consists of a particulate layer approximately 760 nm thick, composed of an electron-lucent layer of widely dispersed granules. Embedded in this layer are electron-dense spheres that project above the surface of this granular layer. Beneath this outermost layer is a band of electron-dense material, consisting of densely packed granules and is half as thick as the outer particulate layer. The 3rd layer consists of relatively thick, weakly laminated chorion, with a felt-like appearance due to a meshwork of microfibrils. Projections of this network of microfibrils form pillars that attach this layer to a thin relatively compact 4th or basal layer. The pillars and the air-filled cavities lying between the 3rd and 4th chorionic layers constitute the chorionic meshwork known as the palisades or trabecular layer that form the major respiratory organ of the eggshell. The trabecular layer is connected to the external environment by means of the lateral and anterior aeroplyes. The vitelline membrane lies between the chorion and oocyte and is a granular, uniform, moderately electron-dense layer measuring approximately 260 nm thick. The micropyle at the posterior of the flea egg consists of a rosette of 50-80 apertures and possesses an internal electron-dense plug between the chorion and the vitelline membrane. An aeropyle at the anterior end of the egg consists of a rosette of 40-50 apertures. An inconspicuous aeropyle appears as a cluster of hexagonal or polygonal-shaped plaques on the lateral surface of the chorion. Each plaque contains 3-8 pores.

Animals↗