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At least 19 recordsLinked to original sources
PubMed1977

Effects of DDT on eggshell quality and calcium adenosine triphosphatase.

Adult mallard ducks were fed a diet containing 50 ppm DDT for 6 months. Eggs laid during this period were collected and eggshell weight, thickness, and calcium were determined. Chronic ingestion of DDT resulted in production of eggshells that were significantly thinner and lighter than those of controls. Total calcium of thinned eggshells was also reduced; however, calcium per gram of eggshell was not altered, indicating that other eggshell constituents were not incorporated as well. Calcium adenosine triphosphatase activity in the microsomal fraction of eggshell gland epithelium was assayed in control and DDT-fed ducks. Enzyme activity in DDT-fed ducks was reduced to 65% of control values. Since Ca-ATPase has been shown to be associated with calcium transport, enzyme inhibition may be responsible for decreased eggshell weight and thickness. Electron microscopic evaluation of microsomal fractions showed elements of the plasma membrane, including cilia and microvilli, as well as rough and smooth endoplasmic reticulum. Inhibition of calcium transport at the plasma membrane of mucosal epithelium is proposed as a possible mechanism of DDT-induced eggshell thinning.

Adenosine Triphosphatases↗
PubMed1979

Structure of the schistosome eggshell: amino acid analysis and incorporation of labelled amino acids.

Preparations of eggshells of Schistosoma mansoni and S. japonicum were hydrolyzed and analyzed for amino acid composition. Both species showed great similarities in the proportions of each residue found. The predominant amino acid in shell hydrolysates was found to be glycine, which accounted for 37% of S. mansoni and 45% of S. japonicum amino acids. Four components (glycine, aspartic acid, lysine, and serine) totalled 68--75% of amino acids in the eggshells. Other individual amino acids were present in relatively small proportions ranging from 5.2--0.01%. Less than 1% of the amino acid residues were identified as tyrosine, and bityrosine was detected at a level not exceeding 1 in 1,600 residues. Carbohydrates were estimated to comprise 7.5--10% of the eggshell weight, based on hexose assay, and glucosamine was identified as the principal amino sugar in shell hydrolysates. In vivo labelling of the S. mansoni eggshell was demonstrated following injection of C14-glycine and C14-tyrosine into infected mice and subsequent purification of the shells of eggs recovered from their liver.

Amino Acids↗
PubMed1979

Effects of organochlorine residues on eggshell thickness, reproduction, and population status of brown pelicans (Pelecanus occidentalis) in South Carolina and Florida, 1969--76.

Shells of brown pelican (Pelecanus occidentalis) eggs collected in South Carolina from 1969 through 1975 and in Florida during 1969, 1970, and 1974 were significantly thinner (P greater than 0.05) than eggshells collected before 1947. Thickness of South Carolina eggshells increased in 1975, and mean thickness of eggshells collected in Florida during 1974 was greater than that of eggshells collected during 1969 and 1970, primarily in Gulf Coast colonies. Residues of 13 organochlorines were found in eggs and tissues of pelicans found dead during 1974 and 1975, although residues in brains of these specimens were not high enough to cause death. Residues of organochlorines, except PCBs, declined through 1975. PCBs increased in eggs from Atlantic Coast colonies. Reproductive success and population status of brown pelicans in South Carolina have improved markedly since authors began their studies in 1969. Good reproductive success was reported in 3 of 5 years from 1973 through 1977.

Animals↗
PubMed1978

Influence of dietary calcium selenium and methylmercury on eggshell thickness in Japanese quail.

A high Ca, semi-purified diet promoted greater egg production with thicker shells in Japanese quail hens. 7 ppm of dietary Se depressed egg weights with no effect on eggshell thickness. The addition of 20 ppm of MHg to either a low or high Ca diet containing Se depressed both egg production and eggshell thickness. Se residues of liver, kidney, and brain in Se-MHg fed quail were significantly higher than in Se treated quail, probably reflecting the ability of Se to bind with Hg. CA, an enzyme required for the formation of the carbonate radical of Ca carbonate in eggshells, was not reduced in the Se-MHg treated Japanese quail hens' blood or oviducts.

Animals↗
PubMed2025

Oocyte surface proteins EGG-1 and EGG-2 are required for eggshell integrity in Caenorhabditis elegans.

Metazoan eggs are surrounded by a specialized coat of extracellular matrix that mediates sperm-egg interactions. This coat is rapidly remodeled after fertilization to form a barrier that prevents polyspermy, protects against environmental insults, and provides structural support to the developing embryo. In C. elegans several oocyte surface proteins have been identified that mediate these events. However, whether two of these proteins, EGG-1 and EGG-2, are required for fertilization or downstream events has been unclear. Here, we address this question using more recent advances in genome editing tools through the creation of egg-1 egg-2 deletions of the endogenous loci. We found that egg-1 egg-2 oocytes are fertilization competent and form rudimentary eggshells. While the integrity of the egg-1 egg-2 eggshells are compromised and often rupture within the uterus, surprisingly, some embryos are capable of undergoing several rounds of cell division. Overall, our findings demonstrate that EGG-1 and EGG-2 are not required for fertilization but are involved in post-fertilization processes.

Caenorhabditis elegans↗
PubMed1978

Some observations on the calcium ion binding to the eggshell matrix.

The calcified matrix of the hen eggshell has been demineralized with the EDTA. Aliquots of this material are soluble in water and have been characterized by column chromatography and by chemical analyses. Of particular interest is the high hexosamine and uronic acid content, which confirms the protein-polysaccharide nature of this water-soluble material. The calcium ion binding to the eggshell matrix has been studied by the equilibrium dialysis technique at different pH values, with both free and blocked carboxylic groups. The material with the free carboxylic side chain groups binds more calcium ions with increasing pH value. When the carboxylic groups have been previously blocked with a water-soluble carbodiimide, the calcium ion binding rapidly decreases. The residual capacity to bind calcium ions in the material with the carboxylic functions modified is probably due to the sulfate ions. In agreement with previous observations on other calcified substrates, the calcium ion binding seems to depend on the presence of ionized carboxylic functions of the matrix.

Amino Acids↗
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↗
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↗
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↗
PubMed1979

Effect of pH on eggshell penetration by Salmonellae.

Experiments were conducted to study effects of pH on penetration of eggs by three species of Salmonella. Eggs having an average specific gravity of 1.078 were subjected to challenge by either S. typhimurium, S. st. paul, or S. derby. Challenge solutions ranged from pH 5.0 to 9.5 in .5 pH increments and contained an average of 7.5 x 10(3) Salmonella/ml. Egg temperature was 22 C and solution temperature 4.4 C when challenged. Tartaric acid (10%) or 1 N. NaOH were used to adjust solution prior to adding challenge organisms. Eggs were challenged for 3 min then allowed to dry and held at 22 C for 24 hr, after which they were opened aseptically. Salmonella penetration was determined by swabbing the inner shell membrane and incubating in selenite cystine and tetrathionate enrichment broths for 24 hr followed by plating on MacConkey and SS agars. Penetration rates for all three organisms were significantly less at pH 5.0 than at any higher pH tested. There was an increase in penetration from pH 5.5 to 7.0 for all species. Maximum penetration rates were 42% of eggs challenged at pH 7.5, 22% at pH 8.5, and 34% at pH 7.0 for S. typhimurium, S. derby, and S. st. paul, respectively. In no case was penetration of eggs at pH 9.0 significantly different from pH at maximum penetration of challenge eggs. Penetration by S. st paul, at pH 9.5 was significantly less (P less than .05) than at pH 7.0. Decalcification of the eggshell was less than .01%/min at pH 4.0. Shell losses at pH 3.5 and 3.0 were .03% and .33%/min, respectively.

Animals↗