Search results for "sea urchin."

Spine and test skeletal matrices of the Mediterranean sea urchinArbacia lixula- a comparative characterization of their sugar signature

2015

15 pages; International audience; Calcified structures of sea urchins are biocomposite materials that comprise a minor fraction of organic macromolecules, such as proteins, glycoproteins and polysaccharides. These macromolecules are thought to collectively regulate mineral deposition during the process of calcification. When occluded, they modify the properties of the mineral. In the present study, the organic matrices (both soluble and insoluble in acetic acid) of spines and tests from the Mediterranean black sea urchin Arbacia lixula were extracted and characterized, in order to determine whether they exhibit similar biochemical signatures. Bulk characterizations were performed by mono-di…

On hidden heterogeneity in directional asymmetry – can systematic bias be avoided?

2006

8 pages; International audience; Directional asymmetry (DA) biases the analysis of fluctuating asymmetry (FA) mainly because among-individual differences in the predisposition for DA are difficult to detect. However, we argue that systematic bias mainly results from predictable associations between signed right-left asymmetry and other factors, i.e. from systematic variation in DA. We here demonstrate methods to test and correct for this, by analysing bilateral asymmetry in size and shape of an irregular sea urchin. Notably, in this model system, DA depended significantly on body length and geographic origin, although mean signed asymmetry (mean DA) was not significant in the sample as a wh…

Effect of environmental stress on sea urchin embryos and larvae: from developmental to molecular biology analyses

2010

SOME COMPARATIVE REMARKS ON THE TRANSIENT CHANGE IN LACTIC ACID CONTENT IN SEA URCHIN EGGS FOLLOWING FERTILIZATION.

1964

Abstract During the first few minutes following fertilization a transient increase in the concentration of lactic acid occurs in the eggs of Arbacia lixula , whereas no change at all is observed in the eggs of Paracentrotus liuidus . In the eggs of Psammechinus miliaris there is a transient decrease, soon followed by a recovery so that the level of the unfertilized egg is again reached.

Identification of GABA receptor genes and evidence of GABA signaling during embryogenesis of the sea urchin

2012

Gamma-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter in the mammalian central nervous system and acts via ionotropic (GABAA-Rs) and metabotropic (GABAB-Rs) receptors. GABAA-Rs are Cl- selective hetero-pentameric channels assembled by combinations of 19 distinct gene products. Instead, GABAB-Rs are bi-subunit G-protein coupled receptors linked to K+ or Ca2+ channels. Dysfunctions of GABA-signaling (GS) cause psychotic disorders and correlate with epigenetic alterations, such as over-expression of DNA methyl transferase-1 which in turn imposes iper-methylation of GABA-regulated genes. The sea urchin embryo, which presents a rudimentary nervous system, offers a big oppor…

Identification of a putative GAGA factor in P. lividus embryos

2015

Hbox12: an old gene with a new function.

2013

Development of Phosphatized Calcium Carbonate Biominerals as Bioactive Bone Graft Substitute Materials, Part I: Incorporation of Magnesium and Stront…

2018

Synthetic materials based on calcium phosphate (CaP) are frequently used as bone graft substitutes when natural bone grafts are not available or not suitable. Chemical similarity to bone guarantees the biocompatibility of synthetic CaP materials, whereas macroporosity enables their integration into the natural bone tissue. To restore optimum mechanical performance after the grafting procedure, gradual resorption of CaP implants and simultaneous replacement by natural bone is desirable. Mg and Sr ions released from implants support osteointegration by stimulating bone formation. Furthermore, Sr ions counteract osteoporotic bone loss and reduce the probability of related fractures. The presen…

Biodiversity of Antarctic echinoids: a comprehensive and interactive database

2005

Eighty-one echinoid species are present south of the Antarctic Convergence, and they represent an important component of the benthic fauna. “Antarctic echinoids” is an interactive database synthesising the results of more than 100 years of Antarctic expeditions, and comprising information about all echinoid species. It includes illustrated keys for determination of the species, and information about their morphology and ecology (text, illustrations and glossary) and their distribution (maps and histograms of bathymetrical distribution); the sources of the information (bibliography, collections and expeditions) are also provided. All these data (taxonomic, morphologic, geographic, bathymetri…

Long non-coding RNAs during embryogenesis of the sea urchin

2014

Intriguing studies suggest that long non-coding RNAs (lncRNAs) tend to act in cis with neighboring protein-coding genes. Based on this notion, we assessed whether lncRNAs originate from adjacent genomic regions of selected protein-coding genes, such as early-H2A histone and strim1, that play important functions during development of the sea urchin Paracentrotus lividus. Downregulation of H2A expression relies on the sns5 chromatin insulator placed at the 3'-end of H2A. Northern blot hybridization show that a lncRNA (of ~600 nt), not overlapping with the H2A mRNA, is transcribed from sns5, following H2A expression. The strim1 locus encodes the first echinoderm TRIM-containing factor which fu…