Search results for "CALCIFICATION"
showing 10 items of 176 documents
The shell matrix and microstructure of the Ram's Horn squid: Molecular and structural characterization.
2020
20 pages; International audience; Molluscs are one of the most diversified phyla among metazoans. Most of them produce an external calcified shell, resulting from the secretory activity of a specialized epithelium of the calcifying mantle. This biomineralization process is controlled by a set of extracellular macromolecules, the organic matrix. In spite of several studies, these components are mainly known for bivalves and gastropods. In the present study, we investigated the physical and biochemical properties of the internal planispiral shell of the Ram's Horn squid Spirula spirula. Scanning Electron Microscope investigations of the shell reveal a complex microstructural organization. The…
Cloning and Targeted Deletion of the Mouse Fetuin Gene
1998
We proposed that the alpha2-Heremans Schmid glycoprotein/fetuin family of serum proteins inhibits unwanted mineralization. To test this hypothesis in animals, we cloned the mouse fetuin gene and generated mice lacking fetuin. The gene consists of seven exons and six introns. The cystatin-like domains D1 and D2 of mouse fetuin are encoded by three exons each, whereas a single terminal exon encodes the carboxyl-terminal domain D3. The promoter structure is well conserved between rat and mouse fetuin genes within the regions shown to bind transcription factors in the rat system. Expression studies demonstrated that mice homozygous for the gene deletion lacked fetuin protein and that mice heter…
An improved high yield method to obtain microsatellite genotypes from red deer antlers up to 200 years old.
2013
Analysis of DNA from older samples, such as museum specimen, is a promising approach to studying genetics of populations and ecological processes across several generations. Here, we present a method for extracting high quality nuclear DNA for microsatellite analysis from antlers of red deer (Cervus elaphus). The genotyping of individuals was based on nine microsatellite loci. Because the amount of DNA found in antlers was high, we could reduce the amount of sample and chemicals used and shorten the decalcification time in comparison to other methods. Using these methods, we obtained genotypes from antlers up to 200 years old.
Biomineralizations: insights and prospects from crustaceans.
2011
19 pages; International audience; For growing, crustaceans have to molt cyclically because of the presence of a rigid exoskeleton. Most of the crustaceans harden their cuticle not only by sclerotization, like all the arthropods, but also by calcification. All the physiology of crustaceans, including the calcification process, is then linked to molting cycles. This means for these animals to find regularly a source of calcium ions quickly available just after ecdysis. The sources of calcium used are diverse, ranging from the environment where the animals live to endogenous calcium deposits cyclically elaborated by some of them. As a result, crustaceans are submitted to an important and energ…
Correlation between osteoporosis and cardiovascular disease
2014
Several evidences have shown in the last years a possible correlation between cardiovascular diseases and osteoporosis. Patients affected with osteoporosis, for example, have a higher risk of cardiovascular diseases than subjects with normal bone mass. However, the heterogeneous approaches and the different populations that have been studied so far have limited the strength of the findings. Studies conducted in animal models show that vascular calcification is a very complex mechanism that involves similar pathways described in the normal bone calcification. Proteins like BMP, osteopontin, osteoprotegerin play an important role at the bone level but are also highly expressed in the calcifie…
Cellular effects of HMG-CoA reductase inhibitors on blood cells (monocytes, macrophages, platelets)
2002
Atherosclerosis is the primary cause of ischaemic heart disease (IHD) and stroke and the leading cause of death and long-term disabilities in westernized societies. Several important environmental and genetic risk factors are associated with atherosclerosis. Over the past decade, it has become evident that atherosclerosis is not simply an inevitable degenerative consequence of ageing, but rather a chronic inflammatory condition connecting altered cholesterol metabolism and other risk factors to the development and progression of the atherosclerotic lesion and its sequelae like plaque rupture, fibrosis, calcification and thrombosis [1].
Brachytherapy heterogeneity correction algorithm
2011
El objetivo de este trabajo de investigación es el estudio de la influencia de heterogeneidades de los tejidos en la dosimetría de braquiterapia. En concreto, hemos desarrollado un algoritmo que tiene en cuenta las calcificaciones localizadas dentro de la próstata y corrige la dosis de referencia en agua. Este algoritmo está basado en un modelo analítico y es aplicable a Sistemas de Planificación del Tratamiento (TPS) comerciales. El modelo analítico tiene un fundamento teórico consistente, y se basa en los valores de referencia (caso homogéneo) y en la definición de una longitud efectiva, que transforma el recorrido dentro de la calcificación en distancias mayores. La energía depositada en…
Orchestin, a calcium-binding phosphoprotein, is a matrix component of two successive transitory calcified biomineralizations cyclically elaborated by…
2003
Orchestia cavimana is a crustacean that cyclically replaces its calcified cuticle during molting cycles in order to grow. Its terrestrial way of life requires storage of calcium during each premolt period, as calcareous concretions, in tubular diverticula of the midgut. During the postmolt period the stored calcium is reabsorbed and is translocated through the storage organ epithelium as calcified small spherules. In a previous study, we sequenced and characterized a remarkable component of the organic matrix of the premolt storage structures, Orchestin, which is a calcium-binding phosphoprotein. In this paper, we analyzed the spatiotemporal expression of the orchestin gene by Northern blot…
The shell matrix of the freshwater mussel Unio pictorum (Paleoheterodonta, Unionoida). Involvement of acidic polysaccharides from glycoproteins in na…
2007
13 pages; International audience; Among molluscs, the shell biomineralization process is controlled by a set of extracellular macromolecular components secreted by the calcifying mantle. In spite of several studies, these components are mainly known in bivalves from only few members of pteriomorph groups. In the present case, we investigated the biochemical properties of the aragonitic shell of the freshwater bivalve Unio pictorum (Paleoheterodonta, Unionoida). Analysis of the amino acid composition reveals a high amount of glycine, aspartate and alanine in the acid-soluble extract, whereas the acid-insoluble one is rich in alanine and glycine. Monosaccharidic analysis indicates that the in…
Comparative ultrastructure and carbohydrate composition of gastroliths from Astacidae, Cambaridae and Parastacidae freshwater crayfish (Crustacea, De…
2012
21 pages; International audience; Crustaceans have to cyclically replace their rigid exoskeleton in order to grow. Most of them harden this skeleton by a calcification process. Some decapods (land crabs, lobsters and crayfish) elaborate calcium storage structures as a reservoir of calcium ions in their stomach wall, as so-called gastroliths. For a better understanding of the cyclic elaboration of these calcium deposits, we studied the ultrastructure of gastroliths from freshwater crayfish by using a combination of microscopic and physical techniques. Because sugars are also molecules putatively involved in the elaboration process of these biomineralizations, we also determined their carbohy…