Reduced Shell Thickness Research Articles

On the use of antibiotics in plasticity research: Gastropod shells unveil a tale of caution.

Through phenotypic plasticity, individual genotypes can produce multiple phenotypes dependent on the environment. In the modern world, anthropogenic influences such as man-made pharmaceuticals are increasingly prevalent. They might alter observable patterns of plasticity and distort our conclusions regarding the adaptive potential of natural populations. Antibiotics are nowadays nearly ubiquitous in aquatic environments and prophylactic antibiotic use is also becoming more common to optimize animal survival and reproductive output in artificial settings. In the well-studied plasticity model system Physella acuta, prophylactic erythromycin treatment acts against gram-positive bacteria and thereby reduces mortality. Here, we study its consequences for inducible defence formation in the same species. In a 2 × 2 split-clutch design, we reared 635 P. acuta in either the presence or absence of this antibiotic, followed by 28-day exposure to either high or low predation risk as perceived through conspecific alarm cues. Under antibiotic treatment, risk-induced increases in shell thickness, a well-known plastic response in this model system, were larger and consistently detectable. Antibiotic treatment reduced shell thickness in low-risk individuals, suggesting that in controls, undiscovered pathogen infection increased shell thickness under low risk. Family variation in risk-induced plasticity was low, but the large variation in responses to antibiotics among families suggests different pathogen susceptibility between genotypes. Lastly, individuals that developed thicker shells had reduced total mass, which highlights resource trade-offs. Antibiotics thus have the potential to uncover a larger extent of plasticity, but might counterintuitively distort plasticity estimates for natural populations where pathogens are a part of natural ecology.

Enriching Atomic Cobalt in an Ultrathin Porous Carbon Shell for Enhanced Electrocatalysis.

Developing nonprecious electrocatalysts operating in acidic and alkaline media for an oxygen reduction reaction (ORR) is essential for sustainable energy technologies. Increasing the metal active site density is an effective strategy to enhance the activity, but it remains challenging because of metal sintering during pyrolysis. Here, we report a novel strategy of enriching atomically dispersed cobalt species in nitrogen-doped carbon for improving the electrocatalytic performance. A hollow carbon nanosphere with reduced shell thickness was obtained by taking advantage of the carbothermic reaction between carbon and ZnO template, and the resulting cobalt enrichment in the ultrathin carbon shell leads to an increase of the density of Co atoms. Together with advantageous microstructure features such as high surface area and multiscale porosity, the corresponding catalyst demonstrated promising oxygen reduction reaction performance in strong acidic and alkaline electrolytes and has two times higher kinetic current density than the nonenriched one. The present work provides an attractive and facile route to engineer active site in electrocatalysts.

QUALIDADE DE OVOS DE PRODUÇÃO ORGÂNICA AO LONGO DE CINQUENTA SEMANAS DE POSTURA

Atualmente, a produção de ovos em sistemas alternativos vem crescendo, porém não há informações relativas aos seus critérios de qualidade. Com o objetivo de analisar características físico-químicas de ovos orgânicos, associadas ao avanço da idade de postura das aves, avaliou-se peso do ovo, altura de albúmen, espessura da casca, índice e porcentagem de gema, porcentagem de albúmen e de casca e unidade Haugh (UH). Quinzenalmente, seis ovos frescos foram avaliados, durante a 28ª e 80ª semana de postura. A qualidade externa e interna dos ovos foi afetada pela idade. Peso do ovo e espessura da casca resultaram em efeito cúbico e quadrático (P<0,001), respectivamente. Avaliação da UH e da porcentagem de gema e albúmen resultaram em comportamento cúbico (P<0,05). Índice de gema teve comportamento linear decrescente. O aumento da idade das aves ocasionou diminuição de indicadores de qualidade interna. Apesar da redução na qualidade, ovos de sistema orgânico mantiveram os padrões adequados para consumo, ao longo do ciclo produtivo. Com o avanço da idade, os ovos ficaram mais pesados, porém com redução da espessura de casca, da unidade Haugh e do índice e porcentagem de gema.

Preparation of Yttria-Stabilized Zirconia Hollow Sphere with Reduced Shell Thickness by Controlling Ambient Temperature during Plasma Process

Yttria-stabilized zirconia (YSZ) hollow sphere (HS) powder is a novel potential feedstock material for the plasma spraying of next generation advanced thermal barrier coatings with low thermal conductivity and high sintering resistibility. In this study, YSZ HS powders were prepared by plasma treatment with/without a heat preservation zone around the flying path of the particles during plasma flame. The results of the scanning electron microscopy of YSZ HS powders showed that HS prepared with a heat preservation zone during the plasma process exhibited a regular spherical morphology and a homogeneous thin shell structure. Due to the sufficient heating of the shell regions, the HS powder presented a well densified shell structure. Furthermore, the mechanism of formation of the HS powder with reduced shell thickness was also discussed based on the analysis of the evolution of the powder structure. This kind of hollow sphere powder with a very thin shell structure provides a new alternative feedstock material for the development of next generation high performance thermal barrier coatings.

Deterioration of eggshell quality is related to calbindin in laying hens infected with velogenic genotype VIId Newcastle disease virus

The aim of this study was to determine the mechanism by which Newcastle disease virus (NDV) affects eggshell quality. Thirty-week-old specific pathogen free (SPF) egg-laying hens were inoculated with the velogenic genotype VIId NDV strain (infected group) or with inoculating media without virus (control group) by combined intraocular and intranasal routes. The levels of CaBP-D28k mRNA expression in the uterus, a gene related to eggshell quality, were examined by quantitative reverse transcriptase polymerase chain reaction (RT-PCR). The quality of eggshells was analyzed by scanning electron microscopy (SEM). The infected group showed a marked decline in egg production when compared to the control group. The NDV antigen was found more abundantly in the glandular epithelium of the infected hens' uteri from 1 to 15 d post-inoculation (dpi). The levels of CaBP-D28k mRNA expression in the uteri of infected hens were significantly lower than in the control hens from 3 to 15 dpi (P < 0.05). The changes in the Ca concentrations in the eggshells were consistent with the expression of CaBP-D28k mRNA in the infected hens. Ultrastructural examination of eggshells showed significantly reduced shell thickness in the infected hens from 1 to 15 dpi (P < 0.05). Furthermore, obvious changes in the structure of the external shell surface and shell membrane were detected in the infected hens compared with the control hens. In conclusion, the current study confirmed that velogenic genotype VIId NDV infection is associated with the deterioration of the eggshell quality of the laying hens.

Biocompatible multilayer capsules engineered with a graphene oxide derivative: synthesis, characterization and cellular uptake.

Graphene-based capsules have strong potential for a number of applications, including drug/gene delivery, tissue engineering, sensors, catalysis and reactors. The ability to integrate graphene into carrier systems with three-dimensional (3D) geometry may open new perspectives both for fundamental tests of graphene mechanics and for novel (bio)technological applications. However, the assembly of 3D complexes from graphene or its derivatives is challenging because of its poor stability under biological conditions. In this work, we attempted to integrate a layer of graphene oxide derivative into the shell of biodegradable capsules by exploiting a facile layer-by-layer (LbL) protocol. As a first step we optimized the LbL protocol to obtain colloidal suspensions of isolated capsules embedding the graphene oxide derivative. As a following step, we investigated in detail the morphological properties of the hybrid capsules, and how the graphene oxide derivative layer influences the porosity and the robustness of the multilayer composite shells. Finally, we verified the uptake of the capsules modified with the GO derivative by two cell lines and studied their intracellular localization and biocompatibility. As compared to pristine capsules, the graphene-modified capsules possess reduced porosity, reduced shell thickness and a higher stability against osmotic pressure. They show remarkable biocompatibility towards the tested cells and long-term colloidal stability and dispersion. By combining the excellent mechanical properties of a graphene oxide derivative with the high versatility of the LbL method, robust and flexible biocompatible polymeric capsules with novel characteristics have been fabricated.

Modulation of Bone-Specific Tissue Regeneration by Incorporating Bone Morphogenetic Protein and Controlling the Shell Thickness of Silk Fibroin/Chitosan/Nanohydroxyapatite Core-Shell Nanofibrous Membranes.

The presence of both osteoconductive and osteoinductive factors is important in promoting stem cell differentiation toward the osteogenic lineage. In this study, we prepared silk fibroin/chitosan/nanohydroxyapatite/bone morphogenetic protein-2 (SF/CS/nHAP/BMP-2, SCHB2) nanofibrous membranes (NFMs) by incorporating BMP-2 in the core and SF/CS/nHAP as the shell layer of a nanofiber with two different shell thicknesses (SCHB2-thick and SCHB-thin). The physicochemical properties of SCHB2 membranes were characterized and compared with those of SF/CS and SF/CS/nHAP NFMs. When tested in release studies, the release rate of BMP-2 and the concentration of BMP-2 in the release medium were higher for SCHB2-thin NFMs because of reduced shell thickness. The BMP-2 released from the nanofiber retained its osteoinductive activity toward human-bone-marrow-derived mesenchymal stem cells (hMSCs). Compared with SF/CS and SF/CS/nHAP NFMs, the incorporation of BMP-2-promoted osteogenic differentiation of hMSCs and the SCHB-thin NFM is the best scaffold during in vitro cell culture. Gene expression analysis by real-time quantitative polymerase chain reaction detected the evolution of both early and late marker genes of bone formation. The relative mRNA expression is in accordance with the effect of BMP-2 incorporation and shell thickness, while the same was reconfirmed through the quantification of bone marker protein osteocalcin. In vivo experiments were carried out by subcutaneously implanting hMSC-seeded SCHB2-thin NFMs and acellular controls on the back sides of nude mice. Immunohistochemical and histological staining confirmed ectopic bone formation and osteogenesis of hMSCs in SCHB2-thin NFMs. In conclusion, the SCHB2-thin NFM could be suggested as a promising scaffold for bone tissue engineering.

Towards tunable defect arrangements in smectic liquid crystal shells utilizing the nematic–smectic transition in hybrid-aligned geometries

We produce and investigate liquid crystal shells with hybrid alignment—planar at one boundary, homeotropic at the other—undergoing a transition between the nematic (N) and smectic-A (SmA) phases. The shells display a dynamic sequence of patterns, the details depending on the alignment agents and on the diameter and thickness of the shell. In shells of sufficient diameter we typically find a transient striped texture near the N–SmA transition, stabilising into a pattern of tiled, more or less regularly spaced focal conic domains in the SmA phase. The domain size and spacing decrease with reduced shell thickness. In case of strong homeotropic anchoring at one boundary and small shell size, however, the increased curvature favors homeotropic against planar alignment in the smectic phase, and the shell then tends to adapt to complete homeotropic alignment at the final stage of the transition. This is the first study of hybrid-aligned smectic shells and the results constitute a beautiful demonstration of the capacity for dynamic structure formation and reformation via self-assembly in soft matter. The new patterns extend the range of arrays of topological defects that can be realised with liquid crystals in spherical morphology and the correlation between the feature arrangements and the variable parameters of the shell and its environment opens a route towards tunability. However, the observed strong impact from increasing curvature, even for these rather large shells, indicates that the choice of alignment agents inducing planar or homeotropic alignment with varying strength will become critical when targeting the most attractive colloidal size scale of about a micron or smaller.

Protoporphyrin and Eggshell Strength: Preliminary Findings from a Passerine Bird

Protoporphyrin pigmentation is a common feature of passerine eggshells worldwide, typically giving red to brown coloration. Although these may form a background colour to the egg, protoporphyrin more commonly forms speckles, blotches or patches of colour (maculation) against a white (unpigmented) or blue/green (biliverdin-pigmented) background. Conventional explanations for the presence of such pigmentation have focused on the eggs’ appearance, and include crypsis and strategies to deter brood parasites, such as cuckoos (Cuculidae). More recently, evidence has emerged that there may also be a sexually-selected visual function. However, the pattern of occurrence across taxa and upon and within the eggshell, suggest that non-visual functions may be at least as important, or even the principal function of some pigmentation. In particular, correlations between protoporphyrin maculation, eggshell thickness, rates of water-loss and local calcium availability in the Great Tit ( Parus major), suggest that the pigment could serve a structural function. Despite strong circumstantial evidence, however, a direct relationship between eggshell strength and protoporphyrin pigmentation has not previously been available. Here, we present preliminary findings from a comparison of fracture toughness (resistance to fracture) and brittleness of pigmented and unpigmented shell from the same Great Tit eggshells. These suggest that while pigmented shell is as brittle as unpigmented shell, the fracture toughness is significantly greater and more than compensates for the reduced shell thickness observed at a pigment spot. The data also suggest that although the first two principal components of pigmentation influence fracture toughness, neither influences how the material responded to the propagation of a crack through its surface. We suggest that pigmentation provides structural overcompensation for shell thinning caused, for example, by a deficit of dietary calcium, and the reasons for this are discussed.

Mineralization of clapper rail eggshell from a contaminated salt marsh system.

The effect of contamination on eggshell mineralization has been studied for clapper rails (Rallus longirostris) inhabiting a contaminated salt marsh in coastal Georgia. To assess the impact of contaminants, the thickness, microstructure (crystal orientation), mineral composition, and chemistry of shell material were analyzed from a contaminated site and a nearby reference site using optical microscopy, X-ray diffraction, inductively coupled plasma mass spectrometry, and gas chromatography with electron capture detector. Eggshells from the contaminated site were generally thinner than those from the reference site. Also, eggshells from the contaminated site were abnormally brittle and contained anomalous microstructural attributes. The combination of reduced shell thickness and anomalous microstructure resulted in weaker eggshells, which in turn could pose a significant threat to the reproductive success of the affected population.PCB concentrations in eggshells were at background levels in both sites. Eggshells from the contaminated site had higher concentrations of heavy metals, specifically mercury, than the reference site. The structural changes observed in eggshells may be related to the concentration of specific metals ( e.g., Mg, Cu, Zn, Pb, and Hg) in shell, however, statistical analyses indicated that metals only explained a small portion of the observed variation in properties ( i.e., thickness, crystal orientation). Further analysis is required to better constrain the factors leading to unusually weak eggshells in the contaminated site.

Relationship of plasma calcium and phosphorus to the shell quality of laying hens receiving saline drinking water

1. From 36 to 43 weeks of age 210 White Leghorn laying hens were used to study the relationship of plasma calcium and phosphorus concentrations to egg-shell quality when saline drinking water was given. 2. Seven experimental treatments in which different amounts of sodium chloride were supplied by the food and/or the drinking water were compared. 3. Increasing salt intake through the drinking water or the food reduced shell thickness and shell calcium, and increased the numbers of damaged eggs. Sodium chloride given in the drinking water was more effective in reducing shell quality and increasing plasma calcium and phosphorus than sodium chloride given in the food.

Research Note: Effect of Biosynthetic Chicken Growth Hormone on Egg Production in White Leghorn Hens

Two studies were conducted to determine if injection of recombinant chicken growth hormone (cGH) influences egg production parameters in older laying hens. In both experiments, hens were subjected to consecutive 3-wk periods consisting of 1) a preinjection period, 2) an injection period, and 3) a postinjection period. During the 3-wk injection period, hens were injected once daily with either 5, 50, or 500 μg/kg BW of cGH or physiological saline (vehicle) alone (control group). In both experiments, injection of cGH did not affect (P>.05) percentage of daily egg production per hen, Haugh units, or BW during the injection period compared with preinjection hens. In Experiment 1, but not Experiment 2, control hens had reduced shell thickness and feed consumption during the injection and postinjection periods when compared with the preinjection controls. These reductions were not observed in hens receiving injections of cGH (all doses).

Dicofol (kelthane®)-induced eggshell thinning in captive american kestrels

Reproductive parameters of American kestrels (Falco sparverius) were measured through two breeding seasons. Exposure to Kelthane® (containing no DDT-related compounds) at dietary concentrations of 0 (control), 1,3, 10 and 30 μg/g (wet weight) began in late November before, and continued through, the second season. Kelthane thinned eggshells and lowered the thickness index at dietary concentrations ≥3 μg/g and it reduced shell weight at ≥10μg/g when comparisons were to concurrent controls. Kelthane reduced the thickness index at ≥3 μg/g and it reduced shell thickness and weight at ≥10 μg/g when comparisons were to the same birds during the previous season. All changes were dose-related. It was not previously known that as little as 3 μg/g dicofol could cause these effects. Kestrels resembled previously studied eastern screech-owls (Otus asio) in that 10 μg/g reduced hatchability of eggs. Both these raptors showed eggshell changes without serious effects on production of young. Available data show dicofol only equal to or less effective than DDE as a shell-thinning agent. Also, DDE may have more impact than dicofol on such critical aspects of reproduction as egg hatchability and survivability of hatchlings. Field studies of dicofol residues in food chains and of residue concentrations in eggs vs. nesting success from areas of heavy dicofol use are needed to judge this chemical's ecological impact.

Production and Egg-Quality Responses of White Leghorn Layers to Anticoccidial Agents

Two studies were conducted to determine the effects of anticoccidial agents on the production and reproduction of White Leghorns. In Experiment 1, nicarbazin (NCZ) was fed at 0, 20, 50, and 100 ppm. Hen-day egg production, egg weight, the egg-yolk DNC (4-4′-dinitrocarbanilide) level, and egg-yolk mottling were affected by the treatments. When response was evidenced, the relationship between those variables and the level of NCZ was basically linear. Decreased egg production occurred from Days 5 and 6 of the treatment through Days 1 and 2 of withdrawal. On Days 9 and 10 of treatment, the control hens peaked at 92% hen-day production, while hens fed 20, 50, and 100 ppm of NCZ peaked late-at 90, 82, and 80%, respectively. Compared to the controls, egg weight was reduced linearly as the level of dietary NCZ increased. The egg-yolk DNC level increased from Days 3 and 4 of treatment through Days 9 and 10 of withdrawal. Egg yolk mottling generally increased along with the level and duration of feeding NCZ. If the NCZ was mistakenly fed to White Leghorn layers, ill effects would be alleviated within 10 days after drug withdrawal.In Experiment 2, halofuginone (3 ppm), maduramicin (5 ppm), monensin (100 ppm), narasin (70 ppm), nicarbazin (125 ppm), robenidine (33 ppm), and salinomycin (60 ppm) were fed to White Leghorn hens at the levels specified in parentheses. Nicarbazin reduced egg production, depressed egg weight, reduced shell thickness, and caused egg-yolk mottling; but internal egg quality, as measured by Haugh Units, was unaffected. Halofuginone, maduramicin, monensin, narasin, robenidine, and salinomycin did not have a meaningful effect on the variables measured when fed to White Leghorn layers.

BHC not found to reduce the shell quality of hens' eggs.

SEVERAL organochloride pesticides are said to have detrimental effects on the eggshell quality of a variety of avian species. The eggshell thickness of ducks is reduced by feeding dieldrin and DDE1,2; that of American kestrels by DDE3; of Japanese quail by DDT4 and of American sparrow hawks by a mixture of DDT and dieldrin5. Indeed, a mathematical relationship seems to exist between DDE residues and shell thinning6. Major structural defects, apart from shell thinning, have also been found to occur in the eggshells of quail fed DDT or chlordecone7. Now that the use of DDT has been, or is about to be, banned in many parts of the world, γ-BHC (lindane) is becoming the most widely used pesticide in this class. However, little is known about its effects on birds. Whitehead et al.8 found that feeding γ-BHC at moderate levels (about 100 mg/kg diet) to hens permanently reduced their egg production by 25%, although no detrimental effect was observed on shell thickness. In contrast, Sauter and Steele9 have claimed that feeding it to hens at a lower level, 10 mg/kg diet, slightly reduced shell thickness.

Effect of ultimobranchialectomy on the laying hen.

Ultimobranchialectomized (UBX) chickens were reared to maturity and through several months of normal egg production. The UBX hens consumed significantly less feed and produced smaller eggs with a trend toward reduced shell thickness. Plasma calcium, phosphorus and alkaline phosphatase activities measured at intervals throughout the eggshell formation cycle exhibited similar diurnal variations in both UBX and SHAM birds. However, the UBX birds had consistently lower values. These studies indicate no major influence of the ultimobranchial glands on normal calcium metabolism in the laying hen.

The Relationships Among Shell Membrane, Selected Chemical Properties, and the Resistance to Shell Failure of Gallus domesticus Eggs

STUDIES of the chemical properties of egg shells and their relationship to shell strength have been very limited. Almquist and Burmester (1934) investigated an abnormal type of shell which they termed a “glassy shell.” It was found to have a reduced shell thickness and breaking strength when compared to normal shells. The “glassy shell” had an average content of 2.38 percent organic material expressed as protein and 95.42 percent calcium carbonate compared to 1.76 percent organic matter and 97.00 percent calcium carbonate in the normal shell. It was further observed that the percentage of protein decreased as the shell thickness increased in normal shells and that the concentration of protein did not influence the breaking strength. Tyler (1958) and Tyler and Geake (1953) reported that the percentages of calcium, magnesium, and carbonate in nitrogenfree shells were practically constant.Similarly, very little research has been attempted to elucidate the chemical composition…

The Effect of High CO2 Atmosphere on the Laying Hen

HALL and Helbacka (1959) demonstrated that feeding NH4Cl to laying hens increased the albumen height and reduced shell thickness during the feeding period. Hunt and Aitken (1962) confirmed this report and suggested that plasma bicarbonate was depressed during feeding of NH4Cl causing thinner shells. The present preliminary study was conducted to determine if changing the acid base balance via the respiratory system would have the same effect as feeding NH4Cl. EXPERIMENTALTrial 1. Four Hy-Line laying hens were kept in an enclosed plastic covered chamber of approximately 6.5 cu. ft. to which a 5% CO2 and 95% gas mixture was metered at 4 liter/min. for a 19-hour period. The birds were returned to a normal gas environment for seven days, then exposed again for a 54-hour period to the same gas mixture. The temperature remained 21°C.±2° and excess moisture was removed with H2SO4. The chamber resembled a closed system. The…

The Effect of Ascorbic Acid on Egg Quality Factors

ABSTRACT REVIEW OF LITERATURE IT HAS been known for many years that high environmental temperatures reduce the thickness of the chicken’s egg shell, thereby lowering its breaking strength. The monetary loss due to this condition has been estimated to be as high as 100 million dollars annually in the United States (Ralston Purina Company, 1957). The usual pattern followed is a gradual thinning of the shell during the spring months becoming progressively greater during the summer, followed by a slow return to normal thickness when the temperature again decreases. This has been shown by Wilhelm (1940), Brant et al. (1953) and many other investigators. Warren and Schnepel (1940) also showed that thinner shells could be produced almost immediately by increasing the environmental temperature from 20°C. to 32.5°C. A recovery in shell thickness occurred rapidly after a subsequent decrease in the temperature. Such findings indicate the possibility that reduced shell thickness is . . .