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PubMedDate not supplied

The effects of ts-11 strain Mycoplasma gallisepticum vaccination in commercial layers on egg production and selected egg quality parameters.

Live Mycoplasma gallisepticum (MG) vaccines have been USDA approved and licensed for use in commercial layer chickens since 1988; however, egg production and egg quality data exist only for the F strain of MG. Information pertinent to the effects of ts-11 MG on egg and eggshell quality parameters, as well as egg size distribution, is lacking. In this study, pullets were inoculated at 10 wk of age with ts-11 strain MG and placed in biological isolation units at 10 birds/unit. Hen-day egg production, eggshell strength, Haugh unit score, pimpling incidence, and blood/meat spot incidence were monitored and recorded in each trial through a 45-wk production cycle. Further, eggs from all treatments were collected daily, Monday-Thursday, and individually weighed. Results of this study indicate that no significant difference was observed between the treatments for the parameters measured or for egg size distribution. Therefore, these data should lessen producers' concerns pertaining to the impact of ts-11 strain MG on egg production, egg and eggshell quality parameters, and egg size distribution.

Animals↗
PubMed2003

The relationship between mediastinal lymph node attenuation with parenchymal lung parameters in silicosis.

OBJECTIVE: Attenuation changes on computed tomography (CT) in mediastinal lymph nodes (LN) may be related to lung alterations and functional impairment in silicosis. DESIGN: CT and clinical data of 41 (64.2 +/- 8.3 years) males with silicosis were retrieved. Attenuation type (calcified, hyperdense, normodense) and calcification pattern (central, eccentric, dense, eggshell, speckled) of mediastinal LN were evaluated; LN attenuation of uncalcified LNs quantified on CT in six LN stations. Nodular profusion (CT-NP) and progressive massive fibrosis (CT-PMF) were graded. Relationships between LN, CT, lung function and clinical parameters were determined. RESULTS: LN sites were paratracheal (n = 39), subcarinal (n = 39), tracheobronchial (n = 37), aortopulmonary (n = 37), hilar (n = 27), and peri-oesophageal (n = 21). LNs were calcified, hyperdense and normodense in 107, 85 and 54 LN stations, respectively. Uniformly calcified LN was most common, followed by speckled calcification. Central, eccentric and eggshell calcification was rare. CT-NP scores > or = 16 were associated with higher LN attenuation and number of calcified LN stations than CT-NP scores < 16. PMF had no influence over LN morphology or calcification pattern. LN attenuation correlated with CT-PMF (r = 0.36, P = 0.01), CT-NP (r = 0.54, P < 0.001) and DLCO/VA (r = -0.33, P = 0.02). CONCLUSION: Uniformly calcified and hyperdense LNs are common in silicosis, and eggshell LN calcification is rare. There are associations between LN attenuation and lung function impairment, and CT grades of nodular profusion and PMF.

Aged↗
PubMed2005

Methylene blue staining method for identification of Opisthorchis viverrini egg.

Methylene blue staining method was used to distinguish O. viverrini eggs from Haplorchis taichui and Prosthodendrium molenkampi eggs. All eggs were obtained from dissected adult worms, fixed in 10% formalin, and stained with methylene blue prior to light microscopy observation. The distinct musk-melon-like texture of the O. viverini eggshell surface and the thread-like texture of H. taichui eggshell surface were recognized, while P. molenkampi eggs showed a smooth eggshell. We also evaluated the sensitivity and specificity of the method by training investigators to differentiate surface textures. After training, the investigators were randomly tested with 10 slides containing fluke eggs. The sensitivity and specificity were 95% and 95%, respectively.

Animals↗
PubMed1991

Effect of acetazolamide on calcium accumulation by the developing chicken embryo.

The injection of 10 mg of acetazolamide into fertile chicken eggs on the 16th or 17th day of incubation resulted in a decreased accumulation of calcium by the developing embryo. A dose of 1 mg of acetazolamide did not affect embryonic calcium content. Although the eggshell serves as the primary source of calcium for the embryo, acetazolamide did not influence eggshell mobilization as measured by the release of 45Ca from labeled eggshells. Acetazolamide did decrease bone formation resulting in a statistically significant reduction in tibia dry weight and calcium content.

Acetazolamide↗
PubMed1988

[Regulation by cations of adenylate cyclase activity in chicken tissues].

The effects of magnesium and sodium ions on adenylate cyclase activity in plasma membranes from chicken heart and eggshell gland mucosa were studied. It was found that the increase in magnesium chloride concentration from 5 to 40 mM results in the stimulation (4.1-fold) of the adenylate cyclase activity. The increase in sodium chloride concentration up to 150 mM stimulated the enzyme activity 2-fold. The stimulation of adenylate cyclase by magnesium and sodium ions was less pronounced in the eggshell gland. GTP did not activate adenylate cyclase. The activating effect of magnesium and sodium ions was accompanied by the attenuation of the enzyme sensitivity to NaF, guanylyl imidodiphosphate and isoproterenol. Activation by guanylyl imidodiphosphate was completely abolished in the presence of 40 mM magnesium chloride. It is assumed that high concentrations of the salt promote subunit dissociation of the adenylate cyclase regulatory protein and its interaction with the catalytic subunit in the presence of endogenous nucleotides. The differences in the adenylate cyclase sensitivity to cations in chicken heart and eggshell gland mucosa correlate with the amount of pertussis toxin substrate.

Adenylyl Cyclases↗
PubMedDate not supplied

Reproductive capacities of control bobwhite quail (Colinus virginianus) during one-generation reproduction studies.

The Bobwhite quail (Colinus virginianus) is the avian model of choice for testing the reproductive impairment potential of pesticides and environmental contaminants. While the literature contains numerous reports on the effects of pesticides on eggshell development for quail, mallards and other avian species (Haegele and Tucker, 1974; Kolaja, 1977; Jenkins et al., 1974) limited control data for reproductive evaluation of pesticides can be found. This paper summarizes the control data from three one-generation reproductive studies in Bobwhite quail. One male and two female adult quail were housed in clean pens with tap water and game bird breeder ration available ad libitum. The pre-laying cycle was ten weeks in duration. The photoperiod was seven hours of light per day for the first eight weeks and was increased to 17 hours of light per day in order to induce egg laying. Eggs were collected daily for eight weeks and incubated. Biweekly, one egg from each pen was removed and used for determination of eggshell thickness. The mean reproductive indices for these studies are: Eggs cracked/Eggs laid--8.2%, Viable 11-day embryos/Eggs set--73.6%, Viable 21-day embryos/Viable 14-day embryos--98.9%, Hatchlings/Viable 21-day embryos--82.0%, 14-day survivors/Hatchlings--76.3%. The mean eggshell thickness for 144 eggs was 0.301 mm.

Animals↗
PubMedDate not supplied

Reduction of fecal shedding and egg contamination of Salmonella enteritidis by increasing the number of heterophil adaptations.

Serial passage of Salmonella enteritidis (SE) in chicken heterophils resulted in heterophil-adapted SE (HASE). We now report that an additional five heterophil passages have further reduced the number and frequency of fecal shedding of HASE. Eleven-times HASE (11 x HASE) given to 12 laying hens for three consecutive days reduced fecal shedding of 11 x HASE to three isolations from fecal samples during the 70-day postexposure observation period. Hens were exposed to challenge SE 74 days after treatment with 11 x HASE. Three of 12 11 x HASE-treated hens were positive for challenge SE (11/396 fecal samples, or 2.8%) between days 5 and 40 postchallenge, whereas all 12 challenge control birds were positive (118/420 fecal samples, or 28.1%) for SE. None of 12 11 x HASE-treated hens was fecal positive from day 9 postchallenge, whereas 10 of 12 challenge control hens (82/372 fecal samples, or 22.0%) remained positive until day 40, the termination of the experiment. None of 525 eggs and eggshells cultured after 11 x HASE exposure was positive for Salmonella, and none of 422 eggs and eggshells cultured after challenge SE exposure was positive for Salmonella. Eggs or eggshells from challenge control hens were positive for Salmonella in 12/479 (2.5%) cases after challenge SE exposure.

Animals↗
PubMed1999

Misexpression of argos, an inhibitor of EGFR signaling in oogenesis, leads to the production of bicephalic, ventralized, and lateralized Drosophila melanogaster eggs.

Epidermal growth factor receptor (EGFR) signaling pathways are frequently involved in generating cell fate diversity in a number of organisms. During anterior-posterior and dorso-ventral polarity in the Drosophila egg chamber and eggshell, EGFR signaling leads to a number of determinative events in the follicle cell layer. A high level of Gurken signal leads to the expression of argos in dorsal midline cells. Lateral follicle cells, receiving a lower level of Gurken signal, can continue to express the Broad-Complex (BR-C) and differentiate into cells which produce chorionic appendages. Misexpression of argos in mid-oogenesis causes the midline cells to retain expression of BR-C, resulting in a single fused large appendage. Evidence that argos can directly repress Gurken-induced EGFR signaling is seen when premature expression of argos is induced earlier in oogenesis. It represses the Gurken signal at stage 5-6 of oogenesis which determines posterior follicle cells and occasionally leads to eggs with anteriors at both ends. We propose that the Gurken signal at stage 9 of oogenesis induces follicle cells to take on two fates, dorsal midline and lateral, each producing different parts of the eggshell and that argos is one of the key downstream genes required to select between these two fates.

Animals↗
PubMed2001

Influence of diminished respiratory surface area on survival of sea turtle embryos.

It has been suggested that fungal presence on sea turtle eggs may impede gas exchange. To investigate the influence of diminished gas exchange surface upon embryo survivorship, flatback (Natator depressus) and green (Chelonia mydas) eggs were painted with petroleum jelly. Variable proportions of the egg surface were covered, including both respiratory and nonrespiratory domains. Embryo survival varied with site inhibited, proportion of eggshell affected, and species of turtle. If fungi on the exterior of the eggshell are able to impede respiratory gas exchange, their presence on the upper hemisphere (primary gas exchange area in early incubation) will result in the highest embryo mortality. Large eggs are likely to demonstrate a higher survivorship than small eggs, due to their larger available respiratory area and/or to variation in weight or stage-specific embryonic metabolic demands. Interspecific differences in egg size may therefore be a contributory factor to observed mortality rate differences in the natural presence of fungi.

Animals↗
PubMed2003

Transitions in the model of epithelial patterning.

We analyze pattern formation in the model of cell communication in Drosophila egg development. The model describes the regulatory network formed by the epidermal growth factor receptor (EGFR) and its ligands. The network is activated by the oocyte-derived input that is modulated by feedback loops within the follicular epithelium. We analyze these dynamics within the framework of a recently proposed mathematical model of EGFR signaling (Shvartsman et al. [2002] Development 129:2577-2589). The emphasis is on the large-amplitude solutions of the model that can be correlated with the experimentally observed patterns of protein and gene expression. Our analysis of transitions between the major classes of patterns in the model can be used to interpret the experimentally observed phenotypic transitions in eggshell morphology in Drosophila melanogaster. The existence of complex patterns in the model can be used to account for complex eggshell morphologies in related fly species.

Animals↗
PubMed2004

spoonbill, a new Drosophila female-sterile mutation, interferes with chromosome organization and dorsal-ventral patterning of the egg.

We have identified a new mutation, spoonbill (spoon), which interferes with two developmental processes during Drosophila oogenesis, nurse cell-nuclei chromatin organization and anterior-dorsal patterning of the eggshell. Here, we describe the localization patterns of key regulators of axis determination and the expression of follicle cell-specific markers involved in eggshell patterning in egg chambers from spoonbill females. Our molecular characterization of the patterning defects associated with the mutation reveals abnormalities in two major signaling pathways, the grk/Egfr and the Dpp/TGF-beta, that together control the elaborate patterning of the anterior follicular epithelium. The function of spoonbill appears to be required for dpp transcription in a specialized population of follicle cells and for the selective transport of grk mRNA from the nurse cells into the oocyte, as well as for its proper localization and translation. This finding places the spoonbill gene upstream of both pathways.

Animals↗
PubMed2005

Experimental analyses of the function of the proepicardium using a new microsurgical procedure to induce loss-of-proepicardial-function in chick embryos.

The proepicardium (PE) is a primarily extracardiac progenitor cell population that colonizes the embryonic heart and delivers the epicardium, the subepicardial and intramyocardial fibroblasts, and the coronary vessels. Recent data show that PE-derived cells additionally play important regulatory roles in myocardial development and possibly in the normal morphogenesis of the heart. Developmental Dynamics 233, 2005. Research on the latter topics profits from the fact that loss-of-PE-function can be experimentally induced in chick embryos. So far, two microsurgical techniques were used to produce such embryos: (1) blocking of PE cell transfer with pieces of the eggshell membrane, and (2) mechanical excision of PE. Both of these techniques, however, have their shortcomings. We have searched, therefore, for new techniques to eliminate the PE. Here, we show that loss-of-PE-function can be induced by photoablation of the PE. Chick embryos were treated in ovo by means of a window in the eggshell at Hamburger and Hamilton (HH) stage 16 (iday 3). The pericardial coelom was opened, and the PE was externally stained with a 1% solution of Rose Bengal by means of a micropipette. Photoactivation of the dye was accomplished by illumination of the operation field with visible light. Examination on postoperative day 1 (iday 4, HH stages 19/20) disclosed complete removal of PE in every experimental embryo. On iday 9 (HH stages 33/34), the survival rate of experimental embryos was 35.7% (15 of 42). Development of the PE-derivatives was compromised in the heart of every survivor. The abnormalities encompassed hydro- or hemopericardium, epicardium-free areas with aneurysmatic outward bulging of the ventricular wall, thin myocardium, defects of the coronary vasculature, and abnormal tissue bridges between the ventricles and the pericardial wall. Our results show that photoablation of the PE is a powerful technique to induce long-lasting loss-of-PE-function in chick embryos. We have additionally obtained new data that suggest that the embryonic epicardium may make important contributions to the passive mechanics of the developing heart.

Animals↗
PubMed2006

Expression of 18-wheeler in the follicle cell epithelium affects cell migration and egg morphology in Drosophila.

The Drosophila ovary is a model system for examining the genetic control of epithelial morphogenesis. The somatic follicle cells form a polarized epithelium surrounding the 16-cell germ line cyst. The integrity of this epithelium is essential for the successful completion of oogenesis. Reciprocal signaling between germ line and somatic cells establishes embryonic and eggshell polarity. The follicle cells are responsible for shaping the egg and secreting the eggshell. Follicle cells at the boundary between the nurse cells and the oocyte migrate centripetally to cover the anterior end of the oocyte and secrete the operculum. Dorsal anterior main body follicle cells undergo elaborate patterning to produce the dorsal appendages. We have examined the expression of the Toll-like receptor, 18-wheeler (18w), in the ovary and find it to be restricted to subpopulations of follicle cells. Females carrying loss-of-function 18w mutant clones in their ovaries show delayed follicle cell migrations. The eggs laid by such females also show morphological defects in egg shape and dorsal appendage morphology. We propose that the 18W protein plays an adhesive or signaling role in regions of the epithelium engaged in cell migration.

Animals↗
PubMed2005

Differing strategies of patterning of follicular cells in higher and lower brachycerans (Diptera: Brachycera).

In all higher dipterans (Brachycera), including the fruitfly, Drosophila melanogaster, each egg chamber (ovarian follicle) consists of a group (clone) of germ cells (one oocyte and 15 accompanying nurse cells) that is surrounded by a layer of somatic mesodermal follicular cells (FCs). As oogenesis progresses the initially uniform FCs diversify into several morphologically and functionally distinct subpopulations. In D. melanogaster some of these subpopulations, e.g., border, centripetal, and dorsolateral cells, undertake coordinated migration or rearrangement over the surface of the germ cells. During the final stages of oogenesis these subpopulations participate in the formation of a complex, regionally specialized eggshell. In representatives of lower brachycerans (Orthorrhapha), only FCs that undertake active, directed migration are the border cells. These cells originate at the anterior pole of the ovarian follicle and migrate between the nurse cells to the anterior pole of the oocyte. Reduced motility of FCs in lower brachycerans results in the absence of certain FC subpopulations in their egg chambers and subsequent simplicity of their eggshells. We found that the lack of some FC subpopulations coincided with the appearance of lamellipodium-like protrusions of the oocyte. These protrusions penetrated between the apposing membranes of nurse and FCs and partially enveloped the nurse cell compartment. Analysis of whole-mount preparations stained with rhodamine-conjugated phalloidin revealed that the protrusions contained microfilaments and that their tips were equipped with actin-rich filopodium-like processes. We also found that in some lower brachycerans (representatives of the family Rhagionidae), the FCs located at the posterior pole of the oocyte, became enlarged and morphologically similar to the anterior border cells. These findings indicate that in higher dipterans the processes leading to the formation of a functional egg are variable and often markedly different from those in the model organism, D. melanogaster.

Actin Cytoskeleton↗
PubMed1990

Development in culture of the chick embryo from fertilized ovum to hatching.

An experiment was carried out to investigate whether thick albumen is essential for the normal development of the chick embryo. Fertilized ova recovered from the oviducts of hens were cultured in vitro and transferred to recipient eggshells with (method A) or without (method B) replacement of the thick albumen by thin albumen. Embryos from freshly laid eggs were transferred to recipient eggshells with (method C) or without (method E) replacement of the thick albumen by thin albumen or with replacement of the thick albumen by thin albumen diluted with solution of salts (method D). Embryos were then incubated until hatching. The rates of hatching of the cultured embryos were 34.4%, 16.2%, 50.0%, 6.9-26.7%, and 47.5% for methods A, B, C, D, and E, respectively. Thus the rate of hatching of cultured fertilized ova was increased by replacement of the thick albumen by thin albumen at the blastoderm stage. Chicks obtained by method A reached maturity and produced viable offspring, and this technique provides an improved method for the culture of fertilized ova to hatching.

Albumins↗
PubMed2003

Histology of the extraembryonic membranes of an oviparous snake: towards a reconstruction of basal squamate patterns.

An understanding of the evolutionary morphology of extraembryonic membranes in reptiles requires information about oviparous as well as viviparous species. We are studying histology and ultrastructure of the extraembryonic membranes of snakes to clarify the evolutionary history of reptilian fetal membranes, including determination of basal (ancestral) ophidian and squamate patterns. Microscopic anatomy of the membranes of oviparous corn snakes (Elaphe guttata) was examined using light and electron microscopy. At mid-development the inner surface of the eggshell is lined by two extraembryonic membranes, the chorioallantois and the omphalallantoic membrane. The chorioallantois consists of a bilayered cuboidal epithelium that overlies the allantoic blood vessels. During development, allantoic capillaries become more abundant, and the chorionic epithelium thins, decreasing the diffusion distance for respiratory gas exchange. The abembryonic pole of the egg is delimited by a bilaminar omphalopleure and isolated yolk mass, the latter of which is lined on its inner face by the allantois. The isolated yolk mass regresses developmentally, and patches of yolk droplets become isolated and surrounded by allantoic blood vessels. By late development, the abembryonic hemisphere has been fully vascularized by allantoic vessels, forming a "secondary chorioallantois." With regard to its extraembryonic membranes, Elaphe gutatta is similar to viviparous snakes. However, this species exhibits features that have not previously been reported among squamates, perhaps reflecting its oviparous reproductive habits. Morphological evidence for the uptake of eggshell material by epithelia of the chorion and omphalopleure suggests that the potential for absorption by extraembryonic membranes predates the origin of viviparity.

Allantois↗
PubMed1992

Ultrastructural and cytochemical aspects of oogenesis in Castrada viridis (Platyhelminthes, Rhabdocoela).

The heterocellular female gonad of the typhloplanoid Castrada viridis consists of a single germarium and two rows of vitellaria. The germarium, composed of a germinative zone and a growth zone, is surrounded externally by a layer of accessory cells the function of which is hypothesized in this study. The main feature of oocyte differentiation is the synthesis of small electron-dense inclusions produced by the rough endoplasmic reticulum (R.E.R.) and Golgi complex. The electron-dense content of the egg inclusions reacts positively to the cytochemical test used to detect polyphenols and is only partially extracted following incubation in protease. The genesis, composition, and peripheral location of egg inclusions in mature oocytes suggest that they could represent residual eggshell granules. The presumed function of eggshell granules is discussed and their fine morphology is compared with that observed in other neoophoran Platyhelminthes.

Animals↗
PubMed2002

Egg of the Karner Blue butterfly (Lycaeides melissa samuelis): morphology and elemental analysis.

Most insect eggshells are ornately sculptured; that of the Karner Blue butterfly, Lycaeides melissa samuelis, exhibits a series of interwoven ridges and depressions. Scanning electron microscopic views of the shell show that the patterning resides in the outer chorion, while the inner vitelline membrane is relatively flat and featureless. We here describe the morphology of the egg and introduce a physical technique, use of a Dynamitron accelerator, to identify and localize elements in the eggshell. Most elements present are represented in the chorion, but sulfur appears restricted to the vitelline membrane. The micropyle is particularly rich in calcium and, in unhatched eggs, phosphorus as well.

Animals↗