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Nombre de programmes trouvés : 1794
Conférences

le (33m0s)

Prof. Bernd Kaspers - The developing immune system of the chicken embryo

Development of hematopoietic cells has been investigated intensively in the chicken embryo. Early hematopoietic stem cells develop in the aortic region and seed to primary lymphoid organs where they mature into T- and B-lymphocytes. Subsequently, they start to colonize the periphery at embryonic day 15/19 and around hatch, respectively. Monoclonal antibodies, recombinant cytokines and new in vivo technologies were instrumental to dissect these pathways. For example, bursal development is dependent on B cell activating factor of the TNF family (BAFF) as shown by retroviral mediated overexpression of BAFF or its decoy receptor ...
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Conférences

le (29m52s)

Prof. Marc McKee - The structure of avian (chicken) eggshell

The functional properties of biomineralized structures found in Nature result from interactions between their hybrid components – both organic (mostly proteins) and inorganic (mineral) phases – to generate hierarchical organization across different length scales.  In its dual function, the calcitic avian eggshell provides a protective barrier for the enclosed developing chick embryo while also serving to provide calcium for the growing chick skeleton by the process of shell dissolution.  Here, a detailed structural analysis (including a description of nanostructure) is given for the eggshell produced by the domesticated chicken, along with changes ...
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Conférences

le (15m38s)

Prof. Alejandro Rodriguez Navarro - Mechanisms of eggshell biomineralization

The avian eggshell is a thin mineral layer (350 µm thick in chicken) that protects the egg content against mechanical impacts, dehydration and microorganism contamination. Eggshell formation is a highly controlled and rapid mineralization process occurring while the egg is residing in the uterus during the night. The composition of the uterine fluid changes at each stage of eggshell formation (initiation, linear growth, termination) with the expression of specific proteins that actively regulate calcium carbonate precipitation, selecting the mineral phase to form (calcite), inducing the nucleation of crystals and controlling ...
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Conférences

le (20m4s)

Dr Liliana D’Alba - Eggshell mineralization in relation to nesting ecology in reptiles

Egg morphology is essential for animal survival, mediating the interactions between embryos and their environment, and a result have evolved into an enormous diversity of forms and functions in modern vertebrates. Reptiles show considerable variation in the degree eggshell calcification, which through evolution shows a tendency to increase. Several hypotheses have been proposed to explain the advantages of intensified mineralization, for example that calcified eggshells increase protection of embryos from mechanical and biological stressors, modulate gas exchange and water physiology or that calcification might be a detoxification mechanism. However, these hypotheses ...
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Conférences

le (17m40s)

Dr Sophie Réhault-Godbert - The eggshell microbiome

Avian eggs possess very efficient and orchestrated systems to protect the embryo during incubation, until hatch. Although the internal components of the egg are assumed to be sterile, the surface of the eggshell is covered by microbes (essentially bacteria) that may contribute to prevent eggshell colonization by pathogenic bacteria, through direct inhibition and/or competitive exclusion. The composition of the eggshell microbiome is a heritage from both maternal microbiota (caeca/faeces) where the egg meets caecal secretions in the cloacal segment during oviposition, and from the nesting environment (contaminated litter/feathers and air environment ...
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Conférences

le (21m31s)

Dr Ian Dunn - The genetics and function of the cuticle, the eggs antimicrobial outer barrier.

Avian eggs have a proteinaceous cuticle covering the outside of the eggshell forming a barrier to the transmission of microorganisms. Although the cuticle is similar to the organic matrix, its secretion is separate from the organic matrix and occurs just prior to oviposition. Using NGS sequence it was possible to investigate genes that might be involved in cuticle deposition, which suggested that an endogenous clock may control events in the uterus, including cuticle deposition. There is considerable variation within breeds of chicken and indeed between species in the quantity of cuticle deposition. ...
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