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The egg of the chicken Gallus gallus, is a giant gamete composed of an oocyte surrounded by nutritive reserves encased in a protective calcium carbonate (CaCO3) layer, the eggshell. The eggshell is essential in the (1) prevention against microbial attacks, (2) metabolic water and gas exchanges during the different development stages and (3) calcium supply for the skeleton mineralisation of embryo. This complex biomineral is composed of 95% CaCO3 and 3.5% organic matrix that contains proteins, polysaccharides and proteoglycans. The organic matrix is secreted by the uterine tissue and controls the different stages of the shell deposition that occurs during a 19h period, making this biomineralisation process one of the fastest in the world. Recent proteomic studies of the organic matrix have quantified and identified hundreds of proteins during eggshell mineralisation and have highlighted 21 proteins, which are suspected to have a predominant role at key stages of CaCO3 deposition. The aim of the project is to better understand the role of these key proteins in stages of the shell mineralisation. In vitro crystallisation using purified proteins and in vivo approaches are required to characterise the protein-mineral interactions and to determine the spatio-temporal biomineralisation process. Moreover, to evaluate the influence of the physiological state of the hen on the eggshell mineralisation, the function and the regulation of the key proteins has been assessed from different physiological states and genetic origin of hens. Finally, results has been compared to other bird species like the Guinea fowl, which produces a thicker and stronger eggshell. This project is a biochemical and molecular study of key proteins in the mineralisation process of the chicken eggshell and could determine new targets for proteomic or genomic selection that may improve the egg quality for human consumption.
I studied Biology at the University of Pierre and Marie Curie (Paris, France) where I worked, during my Master’s internships, on the bone microstructures of fossil and extant vertebrates. I performed my PhD at the University of Burgundy (Dijon, France). My research project focused on the role of the carbonic anhydrase metalloenzyme in the shell biomineralisation processes of the freshwater mussels and abalones. I developed a growing interest in the study of these biomineral structures. After my PhD, I obtained a fellowship for few weeks in Dr Daniel Jackson’s laboratory (Göttingen, Germany) where I learned in situ hybridisation technique. After a year and a half working as assistant lecturer in the University of Limoges (France), I was recruited for a two years post-doctoral position in the Scientific Centre of Monaco. My research project aimed to characterize macromolecules involved in the biomineralisation process of the skeleton of the red coral. Thanks to AgreenSkills, I joined the team DOVE of INRA Centre Val de Loire in 2016 to work on the bird eggshell quality and biomineralisation process using microfluidic qRT-PCR and proteomics approaches.
Nys, Y. and Le Roy, N., 2017. Calcium homeostasis and eggshell biomineralization in female chicken. Chapter 22. In Vitamin D. Volume 1: Biochemistry, Physiology and Diagnostics. Edited by Feldman D, Pike JW, Bouillon R, Giovannucci E, Goltzman D, Hewison M. p 361-382.
Le Roy, N., Jackson, D.J., Marie, B. Ramos-Silva, P. and Marin, F., 2015. Carbonic anhydrase and metazoan biocalcification: a focus on molluscs. Key Engin Mater, 672: 151-157.
Le Roy, N., Jackson, D.J., Ramos-Silva, P., Marie, B. and Marin, F., 2014. Evolution of α-carbonic anhydrases in relation to metazoan CaCO3 biomineralization. Frontiers in Zoology, 11: 75.
Marin, F., Le Roy, N. and Marie, B.,2012. The formation and mineralization of mollusk shell. Frontiers in Biosciences S4: 1099-1125.
Le Roy, N., Marie, B., Gaume, B., Guichard, N., Delgado, S., Zanella-Cléon, I., Becchi, M., Auzoux-Bordenave, S., Sire, J.-Y. and Marin, F., 2012. Identification of two carbonic anhydrases in the shell-forming mantle of the European abalone Haliotis tuberculata (Gastropoda, Haliotidae): phylogenetic implications. J Exp Zool B, 318: 353-367.
2009 Price for poster presentation in the JFBTM congress (national congress)
2010 Price for poster presentation in the Young Researcher Meeting (national congress)
2010 Price for poster presentation in the JFBTM congress (national congress)