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PubMed1994

Organochlorine contaminants and eggshell thinning in grebes from prairie Canada.

Eggs of five species of grebe were collected from Manitoba, Saskatchewan and Alberta during 1982-1987: red-necked (Podiceps grisegena), horned (P. auritus), eared (P. caspicus), western (Aechmophorus occidentalis) and pied-billed (Podilymbus podiceps). DDE and PCBs were present in all samples analyzed, whereas dieldrin, mirex and oxychlordane were occasionally present at low levels. Mercury was present at low levels in all samples for which it was analyzed. Red-necked grebes nesting in Manitoba had the highest contaminant levels and, assuming that contaminant burdens were accumulated principally on the wintering grounds, the mean PCB:DDE ratio (3.1) indicated that these birds and those from sites in central and eastern Saskatchewan probably wintered on the Atlantic coast. Overall low contaminant levels and a low mean PCB:DDE ratio (1.4) in the eggs of red-necked grebes breeding in Alberta and western Saskatchewan suggested that these birds wintered on the Pacific coast. A similar pattern was apparent in horned and eared grebes. Concentrations of DDE and PCB were both significantly correlated with Ratcliffe index (shell thickness), and were strongly correlated with each other. Ratcliffe indices were determined for historical collections of red-necked grebe eggs. Eggshell thickness of grebes nesting in Manitoba declined significantly during the years following the introduction of DDT (post-1947) and has only recovered partially since it was banned in 1972. The Alberta-breeding population did not appear to have undergone any significant decrease in shell thickness.

Journal Article↗

PubMed1985

Relation between Ca2+ uptake and ATPase activity in the particulate fractions of the eggshell gland mucosa of the domestic fowl and duck.

The relation between the rates of ATP-dependent Ca2+ uptake and ATP hydrolysis was studied in homogenates of eggshell gland mucosa and its subcellular fractions from the domestic fowl and duck. The Ca2+-Mg2+-ATPase activity was 5-10% of that of the "basal" Mg2+-ATPase at an optimal Ca2+ concentration in the subfractions. The presence of K+ and/or Na+ increased the rate of Ca2+ uptake and the Ca2+-Mg2+-ATPase activity; the effects of K+-Na+ were not inhibited by ouabain. The Ca/P ratio varied with the experimental conditions. At 10(-4) M Ca2+ and in the absence of K+ Na+ it was 0.8, and in their presence 0.4.

Adenosine Triphosphatases↗

PubMed1984

The lack of relationships between vitamin D3 metabolites and calcium-binding protein in the eggshell gland of laying birds.

The relationship of the metabolism of vitamin D3 and calcium-binding protein (CaBP) to calcium transport by the eggshell gland (ESG) was assessed in chickens. Plasma or ESG 1,25 dihydroxyvitamin D3 (1,25(OH)2D3) and ESG CaBP were no different between periods of ESG inactivity and of shell calcification. A severe dietary calcium deficiency resulted in increased kidney 25-hydroxycholecalciferol-1-hydroxylase activity (542%), plasma and ESG 1,25(OH)2D3 concentrations (193 and 274%, respectively), but in decreased ESG CaBP (34%), associated with the production of poorly calcified eggs. Significant correlations were found between 25 hydroxycholecalciferol-1-hydroxylase, plasma 1,25(OH)2D3 and ESG 1,25(OH)2D3, but not between ESG 1,25(OH)2D3 and CaBP. Hens with a low shell density had a significantly lower (55%) ESG CaBP than those with high shell density, without any significant change in ESG 1,25(OH)2D3. Significant correlations were found between ESG CaBP and shell calcium. Total receptors for 1,25(OH)2D3 were lower in ESG than in the intestine. The results suggest that CaBP level and calcium transport in the ESG are not regulated by 1,25(OH)2D3.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗

PubMed1979

Structural and image analysis of a crystalline layer from dipteran eggshell.

A crystalline layer has been identified as a constituent of the eggshell in the dipteran Drosophila melanogaster. This 400A thick intermediate chorionic layer (ICL) is composed of eight 50A thick sublayers and lies between the vitelline membrane and the endochorion. Whole mount views of isolated ICL after negative staining reveal P2 planar periodicity which, when analyzed further by optical diffraction and filtering, showed 1st (100A), 2nd, 3rd and 4th order reflections.

Animals↗

PubMed1991

A structural protein that plays an enzymatic role in the eggshell of Drosophila melanogaster.

E.S.P. is responsible for the hardening process of the egg-shell at the end of oogenesis (stage 14B) and constitutes a structural component. By immunoblotting, using polyclonal rabbit anti-HRP antibody and anti-rabbit IgG-HRP or Protein A-1251 as second antibody, one major band with MW 38KD on nitrocellulose filter showed positive reaction. We conclude that the E.S.P. is identical to the S38 chorionic protein. Morphological immunogold staining, using pre-embedding procedure, revealed positive reaction in the innermost chorionic layer (ICL) and the endochorion of the eggshell. In addition, electron probe X-ray microanalysis revealed the existence of 37% calcium (explained since the enzyme is Ca2(+)-activated) and 5% iron (explained due to the fact that it is a haemoprotein).

Animals↗

PubMed2004

LacdiNAc (GalNAcbeta1-4GlcNAc) is a major motif in N-glycan structures of the chicken eggshell protein ovocleidin-116.

The avian eggshell matrix protein ovocleidin-116 (OC-116) contains two N-glycosylation sites in its sequence. One of them, 293N-D-S, is modified only marginally while the second one, 62N-Q-T, is completely occupied by N-linked glycans. The glycopeptide bearing the modified site was isolated by size exclusion chromatography and reversed phase HPLC after cleavage of the protein with lysyl endopeptidase. The carbohydrate structures attached to Asn62 were determined by carbohydrate compositional analysis, methylation analysis and electrospray MS/MS. We identified 17 different oligosaccharide structures. Four of them were of the high-mannose type, eight were hybrid type and five were complex type structures. Both, hybrid and complex type glycans comprised core-fucosylated and peripherally fucosylated structures. Most of the antennae contained the relatively rare lacdiNAc (GalNAcbeta1-4GlcNAc) motif, which was fucosylated in 9 out of 15 structures. The lacNAc (Galbeta1-4GlcNAc) motif, which is the more frequent motif in mammals, only occurred in 3 of the 17 glycoforms. This is the first detailed study of N-glycan structures occurring in an avian shell-specific protein and, to our knowledge, the first description of fucosylated lacdiNAc structures present in avian glycoproteins.

Animals↗

PubMed2004

The effect of heavy metal exposure on egg size, eggshell thickness and the number of spermatozoa in blue tit Parus caeruleus eggs.

In this study we compared the egg size, the eggshell thickness and the number of spermatozoa trapped on the perivitelline layer of the eggs in three blue tit (Parus caeruleus) populations across a heavy metal pollution gradient. No significant differences were observed in egg characteristics among study sites. Eggs from the two most polluted sites however, had significantly less spermatozoa on the perivitelline layer than eggs from the least polluted site. Our results suggest a significant effect of pollution on blue tit sperm concentrations in the infundibulum. Determining the number of spermatozoa on the egg membranes is relatively cheap and straightforward, which renders this technique a new and useful tool in biomonitoring.

Animals↗

PubMed2006

Of Eggshells and Thin-skulls: a consideration of racism-related mental illness impacting Black women.

Recent research has indicated that the prevalence of mental disorders is estimated to be higher among Blacks than among Whites, most likely due to the nexus of race and socioeconomic disparity. Blacks are under-represented in in-patient populations and more likely than Whites to use the emergency rooms for mental health treatment. Numerous studies confirm that Blacks drop out of mental health services at a significantly higher rate than Whites and use fewer treatment sessions for mental health issues. Furthermore, Blacks enter mental health treatment at a later, more advanced stage than Whites, under-consume community mental health services of all kinds, are misdiagnosed more often than Whites, and are more often diagnosed with a severe mental illness than Whites. People from diverse ethnic backgrounds often are prevented from receiving adequate mental health treatment due to misdiagnoses and lack of access to the services they need. Factors contributing to this disparity include a general mistrust of medical health professionals, cultural barriers, co-occurring disorders, socioeconomic factors, and primary reliance on family and the religious community during times of distress. Unfortunately, the traditional institutions of racialized research largely ignore the disparate social and political exposures confronting people of color, such as residential and occupational segregation, racial profiling, tokenism, discrimination, racism, and the consequential physiological and psychological effects flowing from the macro and micro effects of such interactions and intersectionalities. This article explores these issues and proposes civil law legal frameworks for addressing these disparities. In particular, it is suggested that renewed consideration be made of the Thin-skull and Eggshell doctrines in the United States and comparable traditional international doctrine.

Black People↗

PubMed2006

Opisthorchis viverrini: identification of a glycine-tyrosine rich eggshell protein and its potential as a diagnostic tool for human opisthorchiasis.

A cDNA encoding a novel eggshell protein (OvESP) with high-glycine (49.2%) and -tyrosine (27.8%) content was cloned from the human liver fluke Opisthorchis viverrini. In the adult parasite, the RNA products of the OvESP gene are limited to the vitelline follicles. They have a size of 800 nucleotides and are already present in 2-week-old juveniles. Immune sera of hamsters, experimentally infected, and humans, naturally infected with O. viverrini, detect bacterially expressed recombinant OvESP (rOvESP). A rabbit anti-rOvESP antiserum only reacts with the shells of intrauterine eggs in tissue sections of the parasite. Comparison of rOvESP with the parasite's excretion/secretion products as diagnostic tools for human opisthorchiasis shows a higher sensitivity (0.82-0.48) and specificity (0.97-0.91) of the recombinant protein in the ELISA technique. But the observed weak cross-reactivity of immune sera from mice infected with Schistosoma mansoni, Schistosoma mekongi, and Fasciola gigantica in Western blots of rOvESP indicates that the diagnostic quality of this protein might be compromised if infections by other trematodes are present.

Amino Acid Sequence↗

PubMed2006

The role of brinker in eggshell patterning.

Drosophila oogenesis provides a useful system to study signal transduction pathways and their interactions. Through clonal analysis, we found that brinker (brk), a repressor of Dpp signaling, plays an important role in the Drosophila ovary, where its function is essential for dorsal appendage formation. In the absence of brk, operculum fates are specified at the expense of dorsal appendage fates. Brk is expressed by most of the oocyte associated follicle cells, starting from stage 8 of oogenesis. Transforming Growth Factor beta (TGFbeta) signaling represses brk expression in both the early stage egg chambers and in the anterior follicle cells. In brk mutant follicle cell clones at the dorsal anterior region, Broad Complex (BR-C) expression is down-regulated in a larger domain than in wild type. We show that BR-C is required for dorsal appendage development. In large anterior BR-C mutant clones, dorsal appendages are absent, and instead, the eggshell has an enlarged operculum like region at the anterior. In addition, we show that the Epidermal Growth Factor (EGF) receptor signaling represses the TGFbeta signaling in oogenesis by up-regulating brk expression. From our results and previously published data, it appears that anterior follicle cells integrate the levels of EGF receptor activation and TGFbeta receptor activation. Operculum fate results when the sum of the level of activation of both pathways reaches a threshold level, and reduction of activity of one pathway can be compensated to some extent by increase in the other pathway.

Animals↗

PubMed2004

A gene family of cathepsin L-like proteases of filarial nematodes are associated with larval molting and cuticle and eggshell remodeling.

Cysteine proteinases are involved in a variety of important biological processes and have been implicated in molting and tissue remodeling in free living and parasitic nematodes. We show that in the lymphatic filarial nematode Brugia pahangi molting of third-stage larvae (L3) to fourth-stage larvae is dependent on the activity of a cathepsin L-like cysteine protease (CPL), which can be detected in the excretory/secretory (ES) products of molting L3. Directed cloning of a cysteine protease gene in B. pahangi and analysis of the expressed sequence tag (EST) and genomic sequences of the closely related human lymphatic filarial nematode Brugia malayi have identified a family of CPLs. One group of these enzymes, Bm-cpl-1, -4, -5 and Bp-cpl-4, is highly expressed in the B. malayi and B. pahangi infective L3 larvae. Immunolocalization indicates that the corresponding enzymes are synthesized and stored in granules of the glandular esophagus of L3 and released during the molting process. Functional analysis of these genes in Brugia and closely related CPL genes identified in the filarial nematode Onchocerca volvulus and the free living model nematode Caenorhabditis elegans indicate that these genes are also involved in cuticle and eggshell remodeling.

Animals↗

PubMed2002

Uptake and recovery of gold ions from electroplating wastes using eggshell membrane.

The animal byproduct, hen eggshell membrane (ESM), was evaluated for its ability to sorb gold ions (dicyanoaurate(I) and tetrachloroaurate(III)) from solutions and electroplating wastewater. The gold uptake was dependent on pH, temperature and co-ions present in the solutions, with pH 3.0 being the optimum value. The equilibrium data followed the Langmuir isotherm model with maximum capacities of 147 mg Au(I)/g dry weight and 618 mg Au(III)/g, respectively. Desorption of sorbed gold(I) with 0.1 mol/l NaOH resulted in no changes of the biosorbent gold uptake capacity through five consecutive sorption/desorption cycles. In column experiments, selective recovery of gold from electroplating wastewater containing various metal ions was noted. The affinity of metal sorption was in the order Au > Ag > Co > Cu > Pb > Ni > Zn.

Animals↗

PubMed2003

Pattern formation: the eggshell holds the cue.

Recent data indicate that Torsolike, a spatial cue for patterning terminal structures of a Drosophila embryo, is stably anchored in the fruitfly eggshell; an as yet unidentified factor is required for the high activity of Torsolike at the embryo termini.

Animals↗

PubMed2003

Intestinal and eggshell calbindin, and bone ash of laying hens as influenced by age and molting.

A series of trials was conducted in order to study the effects of age and molt on intestinal and eggshell gland (ESG) calbindin, and on bone ash. For this purpose an ELISA for chicken calbindin was developed. Age did not significantly affect duodenal or ESG calbindin. Bone ash increased (but not significantly in this study) from 8 to 16 months of age. During molt induction, egg laying was arrested, duodenal and ESG calbindin almost completely disappeared and ovary mass, plasma estradiol and total calcium (Ca) decreased markedly, whereas bone ash and body mass (BW) decreased moderately. During the non-laying period that followed the feed withdrawal period, duodenal and ESG calbindin remained low, whereas plasma estradiol and other estrogen-dependent variables, such as plasma total Ca and bone ash, increased slightly. At the onset of egg production following molting, duodenal and ESG calbindin levels were similar to pre molt level. Bone ash was higher than at the pre molt period. Body mass, small yellow follicles, ovary and oviduct mass and plasma estradiol were lower than their values prior to molt induction. Bone ash contents in the molted hens at the ages of 583 and 820 days were similar to or even slightly higher than those in the non-molted hens, whereas duodenal and ESG calbindin were not significantly different. These results suggest that the improvement of shell quality in the molted birds does not involve mechanisms associated with calbindin synthesis.

Aging↗

PubMed1999

Relationships among age, eggshell thickness and vitamin D metabolism and its expression in the laying hen.

Hens forming uncalcified shells synthesized less 1,25-hydroxycholecalciferol (1,25(OH)2D3) and less duodenal and eggshell gland (ESG) calbindin than normal laying hens. Hens forming thin shells had lower intestinal and ESG calbindin and its mRNA. Reducing ESG calcium (Ca2+) transport by the carbonic anhydrase inhibitor acetazolamide, but not by dietary Ca2+ restriction, reduced ESG calbindin and its mRNA. Two sub-populations of hens characterized by shell thickness (ST) maintained this characteristic throughout the whole production period. The differences between the two sub-populations increased with age. In old laying hens, the two sub-populations responded differently to dietary Ca2+ restriction and to exogenous 1,25(OH)2D3. Those forming a thin shell responded to 1,25(OH)2D3 by a significant improvement in ST. The results suggest that: (a) the mechanism responsible for Ca2+ transport to the egg shell consists of a vitamin D-dependent absorption of Ca2+ and a multi-factor-dependent transfer of Ca2+ to the shell; (b) both steps are, most likely, calbindin-mediated; however, the induction of calbindin gene expression in the ESG is predominantly calcium-dependent; and (c) the apparent defect in vitamin D metabolism or its expression in old hens is typical of, or even exclusive, to thin-shell-forming hens.

Acetazolamide↗

PubMed2002

Molecular cloning of rainbow trout (Oncorhynchus mykiss) eggshell zona radiata protein complementary DNA: mRNA expression in 17beta-estradiol- and nonylphenol-treated fish.

A complementary DNA (cDNA) encoding the eggshell zona radiata protein (RBTZR: AF407574) has been cloned from the liver of estradiol-17beta (E(2))-treated rainbow trout (Oncorhynchus mykiss) by reverse-transcriptase polymerase chain reaction (RT-PCR). A set of degenerate primers homologous to the highly conserved cysteine-rich region of the zona radiata protein gene from salmon, winter flounder, medaka and carp were used for the initial RT-PCR. The resulting PCR product was cloned, sequenced and identified as the Zrp gene fragment based on amino acid sequence similarities. Based on the Zrp sequence from the initial PCR, a pair of gene-sequence primers was designed for 3'- and 5'- random amplification of cDNA ends (RACE). Cloning and sequencing of RACE products showed a 1349-bp Zrp gene encoding a 403-amino acid protein with a theoretical molecular mass of approximately 45 kDa. Alignment of the deduced amino acid sequence reveals that RbtZR is similar to piscine and mammalian zona pellucida proteins. The RbtZR gene, together with the estrogen receptor (ER) and vitellogenin (Vtg) genes, was further characterized and comparatively studied for transcriptional and translational expression in xenoestrogen- (nonylphenol, NP) and E(2)-treated juvenile rainbow trout in a time-course experiment. Northern and slot blot analysis showed that the RbtZR mRNA was expressed, in parallel with the ER and Vtg mRNA, in both NP- and E(2)-treated juvenile rainbow trout. Indirect enzyme-linked immunosorbent assay (ELISA) using monoclonal antibody raised against Atlantic salmon Zrp indicated the translational expression of RbtZR protein in blood plasma samples from NP- and E(2)-treated juvenile trout. The differential time-dependent transcriptional and translational expression and use of Zrp, ER and Vtg as sensitive biomarkers in environmental monitoring of endocrine disrupters in fish is discussed.

Amino Acid Sequence↗

PubMedDate not supplied

Eggshell matrix protein mimics: designer peptides to induce the nucleation of calcite crystal aggregates in solution.

Ansocalcin is a novel goose eggshell matrix protein with 132 amino acid residues, which induces the formation of polycrystalline calcite aggregates in in vitro crystallization experiments. The central region of ansocalcin is characterized by the presence of multiplets of charged amino acids. To investigate the specific role of charged amino acid multiplets in the crystal nucleation, three short peptides REWD-16, REWDP-17 (containing charged doublets), and RADA-16 (alternating charged residues) were synthesized and characterized. The aggregation of these peptides in solution was investigated using circular dichroism, intrinsic tryptophan fluorescence, and dynamic light scattering experiments. The peptides REWD-16 and REWDP-17 induced the polycrystalline calcite crystal aggregates, whereas RADA-16 did not induce significant changes in calcite crystal morphology or aggregate formation in in vitro crystallization experiments. The lattice and morphology of the calcite crystals were characterized using X-ray diffraction and scanning electron microscope. The results discussed in this paper reveal the importance of multiplets of charged amino acid residues toward the nucleation of polycrystalline calcite crystal aggregates in solution.

Amino Acid Sequence↗

PubMed1986

Trans-acting amplification mutants and other eggshell mutants of the third chromosome in Drosophila melanogaster.

We report on the characterization of five third chromosome mutations with strong effects on the formation of the eggshell or chorion. Three mutations, defining two loci, result in substantially reduced follicle cell-specific amplification of the major chorion structural genes and, hence, in underproduction of the corresponding mRNAs and proteins. The other two mutations, though displaying structural chorion abnormalities, appear to have no significant effect on amplification and to express normally the major chorion structural genes. The possible nature of these mutations is discussed.

Animals↗