Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “eggshell”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed1986

Effect of some metal compounds on the Ca2+ binding and Ca2+-Mg2+-ATPase activity of eggshell gland mucosa homogenate from the domestic fowl.

Some metal ions, e.g. Hg2+, Cd2+ and Al3+, can have the effects as ecotoxicological agents, of causing eggshell thinning and breakage in birds. In a homogenate of the Ca2+-secreting part of the eggshell gland mucosa, a study was made of the influence of Hg2+, Cd2+, Cu2+, Pb2+, methyl-Hg+, Zn2+, V3+, Al3+ and Ni2+ in different concentrations on the rate of ATP-dependent 10(-4) M Ca2+ binding. All compounds had an inhibitory action. The most potent metal (Hg2+) produced 50% inhibition (IC50) at 1.1 X 10(-6) M, whereas this value for the least potent compound (Ni2+) was 9 X 10(-4) M. The specific Ca2+-Mg2+-ATPase activity was also inhibited by the tested metal ions. In all cases except methyl-Hg+ the IC50 for this activity was lower than that for Ca2+ binding. The most potent ion in this respect was Cd2+, with an IC50 of 8 X 10(-8) M, and the least potent was methyl-Hg+, with an IC50 of 1.4 X 10(-3) M. Pb2+ and Cd2+ in a concentration range of 10(-5)-10(-4) stimulated the Mg2+-ATPase activity, however, to almost the same extent as 10(-4) M Ca2+. A possible explanation for this effect is that these ions may have an affinity for sites of Ca2+ binding of the polypeptide calmodulin and thereby influence the Ca2+ metabolism of the shell gland mucosa.

Animals↗
PubMed1971

DDE residues and eggshell changes in Alaskan falcons and hawks.

Eggshell thickness after exposure to DDT was reduced by 21.7 percent in Alaskan tundra peregrines, by 16.8 percent in taiga peregrines, by 7.5 percent in Aleutian peregrines, by 3.3 percent in rough-legged hawks, and not at all in gyrfalcons. Tundra peregrine eggs contain an average of 889 parts of DDE per million (lipid basis); taiga peregrine eggs contain 673 parts per million; Aleutian peregrine eggs contain 167 parts per million; rough-legged hawk eggs contain 22.5 parts per million; and gyrfalcon eggs contain 3.88 parts per million. These changes in eggshell thickness and the pesticide residues reflect different degrees of exposure to contamination. There is a highly significant negative correlation between shell thickness and DDE content in peregrine eggs. Tundra and taiga peregrines have fledged progressively fewer young each year since 1966.

Alaska↗
PubMed2025

Detection of the mgtC gene in multidrug-resistant Salmonella sp. based on isolation of chicken eggshell swabs from traditional Surabaya markets.

BACKGROUND: The virulence of Salmonella sp. is increased by the presence of the mgtC gene, which allows the bacteria to survive in environments with low magnesium levels, such as inside macrophages. Salmonella sp. found on eggshells when they show resistance to three or more classes of antibiotics can be classified as multidrug-resistant (MDR) bacteria. AIM: This study aimed to identify the presence of Salmonella sp. MDR and the mgtC gene in chicken eggshell swabs from traditional markets in Surabaya. METHODS: Swab samples were collected from 160 eggs (80 from layer chickens and 80 from free-range chickens) at 10 traditional markets in Surabaya, Indonesia. Isolation and identification were performed using culture media, including Salmonella Shigella Agar, Gram staining, Triple Sugar Iron Agar, Sulfide Indole Motility, Simmons Citrate Agar, Methyl Red and Voges Proskauer, and Urea Agar. Antibiotic sensitivity testing was performed using the disc diffusion method on Mueller-Hinton Agar. Molecular detection of the mgtC gene was performed using polymerase chain reaction. RESULTS: The results showed that 16.87% (27/160) of the samples were detected positive for Salmonella sp. All Salmonella sp. isolates (27) were resistant to Erythromycin (100%). Resistance was also found to Ampicillin (77.77%, 21/27), Tetracycline (29.62%, 8/27), and Ciprofloxacin (18.51%, 5/27). No resistance to chloramphenicol was observed. In addition, eight of the 27 isolates (29.62%) were classified as Salmonella sp. MDR. The Salmonella sp. MDR isolates also carried the mgtC gene at 87.5% (7/8). CONCLUSION: These findings demonstrate the potential global public health threat posed by MDR Salmonella sp. with the mgtC gene, emphasizing the importance of monitoring and controlling antibiotic resistance in humans and animals.

Animals↗
PubMedDate not supplied

Salmonella typhimurium penetration through the eggshell of hatching eggs.

This study was undertaken to demonstrate penetration of Salmonella typhimurium through the eggshell of newly laid broiler hatching eggs. Eggs were challenged either by lightly spraying the bacteria over the blunt end of the egg or by contact with contaminated dry nest litter. Exposure time for both groups was 10 minutes; afterward, all eggs were disinfected and incubated 19 days under normal conditions. Chorioallantoic membranes and yolk sacs were cultured in brain-heart infusion broth on day 19 to demonstrate penetration. Isolation of the bacteria from chorioallantoic membranes and yolk sacs, respectively, were as follows: sprayed group: 100% and 83%; contact group: 59% and 29%. These results showed that although water enhanced S. typhimurium penetration, its presence on the eggshell is not essential for penetration to occur.

Allantois↗
PubMed1992

Molecular architecture of helicoidal proteinaceous eggshells.

I will not attempt to summarize this chapter, which is already a summary. I merely wish to point out that experimental and theoretical evidence to date clearly suggests that antiparallel beta-pleated sheet dictates self-assembly in helicoidal proteinaceous eggshells. Molecular details of this process have started to become clear after the development of the specific, most probably correct, protein structural models in the case of the silkmoths, where amino acid information is available and with the help of several experimental techniques. However, for people seeking universal mechanisms the picture should still be far from complete. Several analogous systems should be studied before providing final answers.

Amino Acid Sequence↗
PubMed1991

Influence of chlorinated hydrocarbons, Hg2+ and methyl-Hg+ on steroid hormone receptors from eggshell gland mucosa of domestic fowls and ducks.

A series of chlorinated hydrocarbons were investigated for their ability to inhibit the binding of tritiated progesterone, dexamethasone and testosterone to their respective cytoplasmic receptors, prepared from the eggshell gland mucosa of the domestic fowl. o,p'-DDE and toxaphene were most potent in inhibiting the binding of progesterone and testosterone to their receptors, while p,p'-DDE was most potent in inhibiting the binding of dexamethasone. The effect of the latter compound on dexamethasone binding was biphasic. There were significant differences between ducks and domestic fowls in the dissociation constant (KD) and maximal number of binding sites (Bmax) for several of the steroid hormones. No effect of steroid binding was observed in the p,p'-DDE-treated ducks that were laying thin-shelled eggs. Some metals were also tested for their ability to inhibit progesterone binding. Hg2+ was most potent (IC50 = 5.8 x 10(-5) M) in this respect, while Cd2+, Pb2+ and Al3+ inhibited the binding only when administered in very high concentrations (10(-3) M). Me-Hg+ was less potent than Hg2+. It is concluded that chlorinated hydrocarbon pesticides may interact with several different steroid hormone receptors. These findings are discussed in relation to some reproductive and other hormonal disturbances observed in birds and mammals.

Animals↗
PubMed1991

Tandemly repeating peptide motifs and their secondary structure in Ceratitis capitata eggshell proteins Ccs36 and Ccs38.

Evidence from amino acid composition, Fourier transform analysis of primary structure and secondary structure prediction suggests a tripartite structure for Ceratitis capitata eggshell proteins Ccs36 and Ccs38, which consists of a central domain and two flanking 'arms'. The proteins, apparently, contain tandemly repeating peptide motifs specific for each domain of the tripartite structure. The central domain of both proteins, which exhibits extensive sequence homology with the corresponding domains of Drosophila melanogaster proteins s36 and s38, is formed by tandem repeats of an octapeptide-X-X-X-Z-Z-Z-Z-Z- (where X = large hydrophobic residue and Z = beta-turn former residue) and its variants. It is predicted to adopt a compact, most probably twisted, antiparallel beta-pleated sheet structure of beta-sheet strands regularly alternating with beta-turns or loops. The central domains of Ccs36 and Ccs38 share structural similarities, but they are recognizably different. The 'arms' of the proteins presumably serving for protein and species-specific functions differ substantially from those of Drosophila melanogaster. In Ccs36, the C-terminal 'arm' is formed by, almost precise, tandem repeats of an octapeptide-Y-X-A-A-P-A-A-S- (X = G or S), whereas the N-terminal 'arm' contains repeats of the octapeptide -Z-Z-Z-A-X-A-A-Z- (X = Q, N or E and Z a beta-turn former). In both 'arms' alpha-helices are predicted, alternating with beta-turns.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Eggshell precursor proteins of Fasciola hepatica, I. Structure and expression of vitelline protein B.

Antibody raised against the major eggshell protein of Fasciola hepatica (vitelline protein B, vpB) is employed to isolate cDNAs from an expression library and to localize the protein in whole worms. Two cDNAs corresponding to the protein are homologous through the N-terminal and C-terminal coding regions and widely divergent internally. No repeated regions are apparent and no significant sequence homology is seen with chorion proteins of other genera although the amino acid composition closely reflects that of other chorion proteins. Microheterogeneity observed in the vpB is due to the presence of multiple coding sequences, transcripts and a gradient of post-translational modification. Relative transcription of the vpB mRNA throughout the female reproductive tract is demonstrated.

Amino Acid Sequence↗
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↗
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↗
PubMed1987

Improving turkey poult quality by correcting incubator humidity to match eggshell conductance.

One of the most important factors determining hatchability of avian eggs is their proper water budget during incubation. We show here that water budget changes of turkey eggs effect not only hatchability but also poult quality. In addition to an increase in hatchability of 3.3%, poult quality was increased by 7.3%. This was achieved by sorting eggs into low (less than 18.5), medium (18.5 to 22.0) and high (greater than 22.0) eggshell mass-specific water vapour, conductance categories and incubating them in matching incubation humidities of 21.8, 26.6 and 31.4 Torr, corresponding to relative humidities of 45, 55 and 65% at 37.5 degrees C, respectively. A total diffusive water loss of 11.5% (range 10 to 14%) of the initial egg mass in 25 d of incubation yielded maximal hatchability and poult quality.

Animals↗
PubMed1972

Specific protein synthesis in cellular differentiation. Production of eggshell proteins by silkmoth follicular cells.

Silkmoth follicles, arranged in a precise developmental sequence within the ovariole, yield pure and uniform populations of follicular epithelial cells highly differentiated for synthesis of the proteinaceous eggshell (chorion). These cells can be maintained and labeled efficiently in organ culture; their in vitro (and cell free) protein synthetic activity reflects their activity in vivo. During differentiation the cells undergo dramatic changes in protein synthesis. For 2 days the cells are devoted almost exclusively to production of distinctive chorion proteins of low molecular weight and of unusual amino acid composition. Each protein has its own characteristic developmental kinetics of synthesis. Each is synthesized as a separate polypeptide, apparently on monocistronic messenger RNA (mRNA), and thus reflects the expression of a distinct gene. The rapid changes in this tissue do not result from corresponding changes in translational efficiency. Thus, the peptide chain elongation rate is comparable for chorion and for proteins synthesized at earlier developmental stages (1.3-1.9 amino acids/sec); moreover, the spacing of ribosomes on chorion mRNA (30-37 codons per ribosome) is similar to that encountered in other eukaryotic systems.

Animals↗
PubMed1978

Secretory kinetics in the follicular cells of silkmoths during eggshell formation.

Procedures for quantitative autoradiography were used for studying the process of secretion of eggshell (chorion) proteins in the follicular epithelium of silkmoths. The method was based on photometric measurements of the reflectance of vertically illuminated autoradiographic silver grains. Results were analyzed and plotted by computer. Secretory kinetics were also determined by analysis of labeled proteins in physically separated epithelium and chorion. Rapid accumulation of radioactivity into "clumps" visualized by light microscope autoradiography and evidence from preliminary electron microscope autoradiography indicate that, within 2 min from the time of synthesis, labeled chorion proteins move to Golgi regions scattered throughout the cytoplasm. The proteins begin to accumulate in the apical area 10-20 min later and to be discharged from the cell. The time for half-secretion is 20-25 min, and discharge is essentially complete 30-50 min after labeling. At the developmental stages examined, the kinetics of secretion appear to be similar for all proteins. Within the chorion the proteins rapidly assume a characteristic distribution, which varies for different developmental stages. Two relatively slow steps have been identified in secretion, associated with residence in Golgi regions and in the cell apex, respectively. By contrast, translocation of proteins across the cell and deposition of discharged proteins in the chorion are rapid steps.

Animals↗
PubMed1968

Chlorinated hydrocarbons and eggshell changes in raptorial and fish-eating birds.

Catastrophic declines of three raptorial species in the United States have been accompanied by decreases in eggshell thickness that began in 1947, have amounted to 19 percent or more, and were identical to phenomena reported in Britain. In 1967, shell thickness in herring gull eggs from five states decreased with increases in chlorinated hydrocarbon residues.

Animals↗