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PubMed1995

The relative fracture strengths of the inner and outer surfaces of the eggshell of the domestic fowl.

A method is described for comparing the strength of the material near the inner and outer surfaces of the eggshell of the domestic fowl. Half eggs with blunt poles, obtained by cutting the egg around the equator, were subjected to concentric loading through neoprene O-rings, respectively 7 mm and 15.5 mm diameter. A finite element solution for the stress distribution showed that the point of maximum tensile stress lay on the line of the smaller ring. For downward loading on the smaller ring, the maximum stress occurred on the inner surface of the shell. For upward loading it moved to the outer surface. Upward loading gave a value for the average fracture stress of the outer surface of the shell (27.3 Nmm-2). For downward loading fracture occurred on the outer surface at the larger ring before the fracture stress was reached on the inner surface. This measurement gave a lower bound to the average fracture stress of the inner surface (30.4 Nmm-2). The fracture stress of the inner surface was measured using concentric loading along the axis of the whole egg. The average fracture stress was 36.7 Nmm-2 so the inner surface is 34% stronger than the outer surface.

Animals↗

PubMed1996

Evolution of the dec-1 eggshell locus in Drosophila. III. Sequence comparisons of the simulans complex repeated domain reveal non-concerted evolution.

The X-linked female sterile locus dec-1 (defective chorion-1) was examined in the closely related species D. simulans, D. mauritiana, and D. sechellia (the simulans complex). This locus encodes important eggshell proteins produced in the follicle cells during stages 9 and 12 of oogenesis. In D. melanogaster four variant protein forms have been found, differing in 2-3 kDa each. The variation is due to deletions of 1, 2, or 3 units of a 5-times repeated sequence (78 bp long) of the central coding region. The same type of deletions were found in two variants of D. simulans; in this species, however, the maximum number of repeats observed so far is four. The island species D. mauritiana and D. sechellia both have the repeat sequence repeated three times. Sequence comparisons revealed that the repeats in the simulans complex have been less homogenised by the forces of concerted evolution than the repeats in D. melanogaster. Two domains of the repetitive region that evolve at different rates and are subject to different mechanisms of DNA turnover were also defined.

Amino Acid Sequence↗

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↗

PubMed1969

Dieldrin and DDT: effects on sparrow hawk eggshells and reproduction.

Patterns of reproductive failure in declining populations of several European and North American raptorial species were duplicated experimentally with captive American sparrow hawks Falco sparvcrius that were given a diet containing two commonly used organochlorine insecticides. Major effects on reproduction were increased egg disappearance, increased egg destruction by parent birds, and reduced eggshell thickness.

Animals↗

PubMed2006

Mechanical properties and biocompatibility of soluble eggshell membrane protein/poly(vinyl alcohol) blend films.

Poly(vinyl alcohol) (PVA) has been blended with soluble eggshell membrane protein (SEP) to improve the mechanical properties of SEP film that is brittle. Tensile strength and elongation-at-break increase with increasing amount of PVA. When the SEP/PVA proportion is 1:1, a strong and flexible film is obtained, having a tensile strength of 22.7 MPa and elongation-at-break of 106%. Although scanning electron microscopy observation of the freeze-fractured cross-section shows microphase separation, interaction between SEP and PVA exists, as revealed by FT-IR. NIH3T3 cell culture demonstrates that SEP/PVA blend films with up to 50% of PVA show biocompatibility comparable to pure SEP film.

3T3 Cells↗

PubMed1984

Parathyroid hormone responses to calcium stress during eggshell calcification.

PTH bioactivity during the egg-laying cycle of the chicken has been measured by the cytochemical bioassay for PTH. During the period of eggshell calcification, PTH bioactivity is elevated. After completion of the shell the plasma PTH falls to a low level but is slightly raised again 2 h after ovulation. These results indicate that changes in bioactive PTH play an important role in the calcium metabolism of the chicken during this physiological calcium stress.

Animals↗

PubMed1995

Mutations in the Drosophila gene bullwinkle cause the formation of abnormal eggshell structures and bicaudal embryos.

Subcellular localization of gene products and cell migration are both critical for pattern formation during development. The bullwinkle gene is required in Drosophila for disparate aspects of these processes. In females mutant at the bullwinkle locus, the follicle cells that synthesize the dorsal eggshell filaments do not migrate properly, creating short, broad structures. Mosaic analyses demonstrate that wild-type BULLWINKLE function is required in the germ line for these migrations. Since the mRNA for gurken, the putative ligand that signals dorsal follicle cell fate, is correctly localized in bullwinkle mutants, we conclude that our bullwinkle alleles do not affect the dorsoventral polarity of the oocyte and thus must be affecting the follicle cell migrations in some other way. In addition, the embryos that develop from bullwinkle mothers are bicaudal. A KINESIN:beta-GALACTOSIDASE fusion protein is correctly localized to the posterior pole of bullwinkle oocytes during stage 9. Thus, the microtubule structure of the oocyte and general transport along it do not appear to be disrupted prior to cytoplasmic streaming. Unlike other bicaudal mutants, oskar mRNA is localized correctly to the posterior pole of the oocyte at stage 10. By early embryogenesis, however, some oskar mRNA is mislocalized to the anterior pole. Consistent with the mislocalization of oskar mRNA, a fraction of the VASA protein and nanos mRNA are also mislocalized to the anterior pole of bullwinkle embryos. Mislocalization of nanos mRNA to the anterior is dependent on functional VASA protein. Although the mirror-image segmentation defects appear to result from the action of the posterior group genes, germ cells are not formed at the anterior pole. The bicaudal phenotype is also germ-line dependent for bullwinkle. We suspect that BULLWINKLE interacts with the cytoskeleton and extracellular matrix and is necessary for gene product localization and cell migration during oogenesis after stage 10a.

Animals↗

PubMed1981

The secretion of the eggshell of Schistocerca gregaria, analysis of the kinetics of secretion in vitro by light and electron microscope autoradiography.

The secretion of the 2 main layers (endochorion and exochorion) of the eggshell of the desert locust Schistocerca gregaria was investigated using light and electron microscope autoradiography. Follicles undergoing endochorion secretion were labelled using a 3 min 'pulse' of [3H]leucine in vitro followed by a 0-115 min non-radioactive 'chase'. Immediately after the pulse the silver grains were distributed over the cytoplasm and organelles including rough endoplasmic reticulum, while by 2 and 5 min Golgi bodies contained radioactivity. By 12 min from the beginning of the chase the cell apex containing small secretory vesicles was labelled. By 20 min most of the silver grains were over the endochorion. The half-transport time (t50) was 14--15 min (from mid pulse), the lag time was 9--10 min and the percentage transport rate was 14--15% per min. When a 3 min pulse of [3H]galactose was used to label exochorion precursors, the shorter t50 (11 min) and the clumped grain distribution in light microscope autoradiographs after 0-min chase suggested that galactose was incorporated in Golgi bodies. The secretion of exochorion precursors appears to occur at a similar rate to that of endochorion precursors (approximately 15% per min). The results indicate that the follicle cells are among the fastest secreting cells.

Animals↗

PubMed1992

Homeostasis as regulated by activated macrophage. IX. Enhancement effect of LPSw (a lipopolysaccharide from wheat flour) on hen egg-laying and breaking strength of eggshell.

Oral administration of LPSw (a lipopolysaccharide from wheat flour) given at 60 micrograms/hen/d in drinking water, markedly enhanced eggshell strength. The monthly percentage of eggs laid with a shell strength of more than 4 kg to the total number of eggs was 32% in the group given LPSw in drinking water while it was 12% in the control group given plain water. At the same time, LPSw caused a 30% enhancement of total monthly number of eggs laid over that of control.

Animals↗

PubMed2002

The role of DDE, PCB, coplanar PCB and eggshell parameters for reproduction in the white-tailed sea eagle (Haliaeetus albicilla) in Sweden.

The reproduction of white-tailed sea eagles was monitored in 1964-1999 in 3 differently contaminated sub-populations: Baltic Sea coast (Bp), inland central Sweden (Ip) and Lapland (Lp). 249 dead eggs from 205 clutches were obtained for analyses of DDE and PCBs and for eggshell measurements. A desiccation index (Di) value was calculated for each egg as a measure of water loss through the shell. In the highly contaminated Bp, p,p'-DDE concentrations in the eggs decreased continuously and 5-fold during the study period and PCB concentrations decreased 3-fold from the mid 1980s. The PCB pattern changed slightly over time towards more high-chlorinated congeners but the relative toxicity of the PCB mixture, expressed as 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ), remained constant and TEQ can be assumed to have decreased in a similar way as PCB over time. Productivity (P), shell thickness (St), shell index (Si) and Di increased over time in the Bp but no change in Di or productivity occurred in the Lp, where residue concentrations were 5-8 times lower. P of the Bp was not correlated to St or Si but was negatively correlated to Di, DDE and PCB. An S-shaped dose-response relationship was indicated between P and DDE. After 1988, when the PCB/DDE ratio was considerably higher than previously, PCB but not DDE concentrations were significantly higher in eggs with dead embryos as compared to undeveloped eggs, implying lethal concentrations of PCB, and a LOEL of 320 pg g-1 TEQ is suggested for embryo mortality. In a subset of 21 eggs, representing productive and unproductive females, analyzed for a selection of coplanar PCB congeners, tris(4-chlorophenyl) methanol and bis(4-chlorophenyl) sulphone, there was no evidence for a correlation between P and any of these compounds. A reduction in residue concentrations in old females did not lead to increased P or improved Di-values, indicating a remaining effect from a previous, higher exposure to contaminants. The inability to reproduce included a high rate of undeveloped eggs, indicating effects at a prezygotic stage. P showed the strongest correlation with Di, and Di was most strongly correlated to DDE. Thus, the remaining effect of previous exposure resulted in a stronger correlation to the symptom (Di) rather than to the suggested causative agent (DDE). LOEL values for depressed P were estimated at 120 micrograms g-1 DDE and 500 micrograms g-1 PCB (lipid basis). It is concluded that the major reason for depressed P during the study period was DDE, but that effects also from PCB were largely concealed by the effects from DDE.

Animals↗

PubMedDate not supplied

Eggshell calcification of kidney in ureteropelvic junction obstruction.

Eggshell calcification of kidney in case of ureteropelvic junction obstruction (UPJO) is an uncommon finding with only a few cases reported in literature. We report a thirty-year-old symptomatic man with curvilinear calcification in hydronephrotic right kidney. Thorough investigations to rule out genitourinary tuberculosis and hydatid disease of kidney were performed prior to the definitive management by laparoscopic approach.

Adult↗

PubMed1990

Differential regulation of calbindin-D28K mRNA in the intestine and eggshell gland of the laying hen.

The effect of shell calcification and 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on calbindin-D28K (previously known as vitamin D-dependent calcium-binding protein) and calbindin mRNA was investigated in the intestine and eggshell gland (ESG) of juvenile female chicks, laying hens and non-laying female birds with active gonads. Increasing amounts of 1,25-(OH)2D3 were fed to laying hens and juvenile birds treated with oestradiol to develop the ESG. The intestinal concentration of calbindin was increased 30-fold by 1,25-(OH)2D3 in chicks treated with oestradiol and fed a vitamin D-deficient diet. In these same animals, 1,25-(OH)2D3 had no effect on the formation of calbindin mRNA or calbindin in the ESG even though fully viable 1,25-(OH)2D3 receptors are present in this tissue. In laying birds fed adequate amounts of vitamin D3, intestinal, but not ESG, calbindin was increased by the addition of 1,25-(OH)2D3 to the diet. At the onset of egg production the concentrations of calbindin and calbindin mRNA were increased in the intestine and ESG. This increase occurred within the period of calcification of the first egg, through a process unaffected by vitamin D. Calcification of the first egg increased the concentration of calbindin in the ESG by eight- to tenfold, although the concentration of calbindin mRNA was increased by only two- to threefold. These results suggest that the induction of calbindin synthesis by 1,25-(OH)2D3 or by the egg calcification process is associated with an increase in the concentration of calbindin mRNA in the ESG and intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Collagens of the chicken eggshell membranes.

An immunohistochemical analysis of the eggshell membranes shows the occurrence of type X collagen while type I collagen was not detected by using an appropriate monoclonal antibody with untreated shell membranes. A positive immuno-reaction for type I collagen was obtained after digestion of the shell membranes with pepsin. These observations indicate the possibility that type I collagen epitope was masked by type X collagen and that type X collagen may serve as an inhibitory boundary for biomineralization.

Acetates↗

PubMed2000

Surgical correction of lumbar kyphotic deformity: posterior reduction "eggshell" osteotomy.

OBJECT: Progressive kyphotic deformity of the lumbar or thoracolumbar spine may lead to back pain, cosmetic deformity, and risk of neurological compromise. The authors describe a series of patients in whom they performed a single-stage, posterior reduction ("eggshell") osteotomy procedure to improve sagittal contour by creating lordosis within a single vertebral body. METHODS: From 1995 to 1997 the authors performed 12 osteotomy procedures in 11 patients with thoracolumbar or lumbar kyphosis. Seven patients presented with iatrogenic deformity, three with deformity secondary to traumatic injury, and one patient with ankylosing spondylitis. Their mean age at time of surgery was 46.6 years (range 23-78 years). All patients suffered from back pain and were unable to stand upright, but in only one patient were neurological findings demonstrated. The mean preoperative deformity was -26 degrees (range -90 to 0 degrees). At 6-month follow-up examination the mean sagittal contour measured 17.5 degrees (range - 17 to 44 degrees), indicating that the mean surgical correction was 40.1 degrees (range 25 to 58 degrees). All patients reported decreased back pain at follow up, and none required narcotic analgesic medication. Complications included a dense paresis that developed immediately postoperatively in a patient who was found to have residual dural compression, which was corrected by emergency decompressive surgery. One elderly patient suffered a perioperative cerebrovascular accident, and three patients suffered neurapraxia with transient muscle weakness of the quadriceps. There was one case of a dural tear. There were no deaths, and prolonged intensive care stays were not required. CONCLUSIONS: Single-level posterior reduction osteotomy provides excellent sagittal correction of kyphotic deformity in the lumbar region, with a risk of cauda equina and root and plexus compromise due to the extensive neural exposure.

Adult↗

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↗

PubMed1985

Arterial blood gas, pH, and bicarbonate values in laying hens selected for thick or thin eggshell production.

Bicarbonate, pH, carbon dioxide partial pressure (pCO2), and oxygen partial pressure (pO2) were measured in blood samples collected anaerobically from the brachial arteries of domestic fowl from lines selected for thick (TK) or thin (TN) eggshell production. The blood values of TK and TN hens were compared 6 hr prior to oviposition and continued at 2-hr intervals until 10 hrs postoviposition. Percent shell values were measured for eggs laid 2 days prior to and during blood sampling. Hens with TK shells had significantly (P less than .001) higher percent shell values than hens with TN shells. The measured blood parameters (bicarbonate, pH, pCO2, and pO2) did not differ significantly (P greater than .05) when TK and TN hens were compared at the time of oviposition. However, between 2 and 6 hr postoviposition, TN hens had significantly lower blood pH, pO2, and bicarbonate than did TK hens. Arterial pCO2 tended to be higher in TN hens than in TK hens, but this difference was significant only at 6 hr preoviposition. These results show that TN hens develop metabolic acidosis relative to TK hens during the first 6 hr postoviposition.

Acidosis↗

PubMed1987

Eggshell quality as influenced by sodium bicarbonate, calcium source, and photoperiod.

The effects of Ca source (limestone or a mixture of one-third limestone and two-thirds oyster shell), NaHCO3 (0 or .5%) and feeding photoperiod (16 or 24 hr) were studied in a 16-week experiment involving 240 Hy-Line W-36 Leghorn hens, 25 weeks of age. Neither egg production (percent hen-day and egg mass, kg egg/bird per 16 weeks) nor feed conversion ratio (kg feed per kg egg) were significantly (P greater than .05) affected by dietary treatment or photoperiod. However, extending the photoperiod to 24 hr significantly (P less than .05) increased feed consumption with a consequent increase in egg weight (P less than .01). Feeding oyster shell in combination with limestone significantly (P less than .05) improved specific gravity of eggs, whereas dietary NaHCO3 significantly (P less than .01) improved elasticity of the egg shell as measured by deformation. Eggshell quality was improved by increasing the photoperiod to 24 hr and was most pronounced when hens were fed diets supplemented with .5% NaHCO3 and limestone as the only source of Ca.

Animals↗

PubMed1987

Effects of eggshell cuticle removal and incubation humidity on embryonic development and hatchability of broilers.

The effects of eggshell cuticle removal and two levels of incubation humidity 28.3 C [50% relative humidity (RH)] and 30.0 C (55% RH) wetbulb temperature (WB) on embryonic mortality and hatchability were determined from broiler hatching eggs laid during 38, 42, 48, and 54 weeks of age. Variables measured were: egg weight loss during the first 17 days of incubation, hatch at Days 19.5 and 20.5 of incubation, hatch of fertile eggs, stage of embryonic mortality, and chick weight at 21.5 days of incubation. Day 0 to 17 percentage egg weight loss was increased when the incubation humidity was lowered and the loss was greater than that observed after cuticle removal. A greater percentage of chicks hatched on Day 19.5 at 28.3 C than at 30.0 C WB. The percentage hatch of 38-week fertile eggs was improved at the higher humidity; the higher humidity also decreased late dead and increased pipped embryonic mortalities. Cuticle removal decreased early dead and increased late dead mortality. At Week 38 cuticle removal and lower humidity resulted in a decrease in chick weight at 21.5 days of incubation. For Weeks 42, 48, and 54 combined, pipped mortality was increased by higher humidity and late dead mortality was increased by cuticle removal. Water loss from the egg was increased by cuticle removal or by lowering incubation humidity from 30.0 C to 28.3 C WB, or by both, but lowering humidity was more effective. Changes in humidity and cuticle removal may affect vital gas exchange to different degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗