0000000000040693
AUTHOR
Irina Bundeleva
Organic matrices in metazoan calcium carbonate skeletons: composition, functions, evolution.
9 pages; International audience; Calcium carbonate skeletal tissues in metazoans comprise a small quantity of occluded organic macromolecules, mostly proteins and polysaccharides that constitute the skeletal matrix. Because its functions in modulating the biomineralization process are well known, the skeletal matrix has been extensively studied, successively via classical biochemical approaches, via molecular biology and, in recent years, via transcriptomics and proteomics. The optimistic view that the deposition of calcium carbonate minerals requires a limited number of macromolecules has been challenged, in the last decade, by high-throughput approaches. Such approaches have made possible…
The shell of the invasive bivalve species Dreissena polymorpha: biochemical, elemental and textural Investigations.
28 pages; International audience; The zebra mussel Dreissena polymorpha is a well-established invasive model organism. Although extensively used in environmental sciences, virtually nothing is known of the molecular process of its shell calcification. By describing the microstructure, geochemistry and biochemistry/proteomics of the shell, the present study aims at promoting this species as a model organism in biomineralization studies, in order to establish a bridge with ecotoxicology, while sketching evolutionary conclusions. The shell of D. polymorpha exhibits the classical crossed-lamellar/complex crossed lamellar combination found in several heterodont bivalves, in addition to an extern…
Skeletal organic matrices in molluscs: origin, evolution, diagenesis
8 pages; International audience; The mollusc shell comprises a small amount of organic macromolecules, mostly proteins and polysaccharides, which, all together, constitute the skeletal organic matrix (SOM). In the recent years, the study of the SOM of about two dozens of mollusc species via transcriptomics and/or proteomics has led to the identification of hundreds of shell-associated proteins. This rapidly growing set of data allows several comparisons, shedding light on similarities and differences at the primary structure level and on some peculiar evolutionary mechanisms that may have affected SOM proteins. In addition, it constitutes a prerequisite for investigating the SOM repertoires…
Metazoan calcium carbonate biomineralizations: macroevolutionary trends – challenges for the coming decade
AbstractCalcium carbonate-based biominerals, also referred as biocalcifications, are the most abundant biogenic mineralized products at the surface of the Earth. In this paper, we summarize general concepts on biocalcifications and we sketch macro-evolutionary trends throughout the history of the Earth, from Archean to Phanerozoic times. Then, we expose five fundamental issues that represent key-challenges in biocalcification researches for the coming decade: the first one concerns the comprehension of the micro- and nano-structure of calcium carbonate biominerals from a mineral viewpoint, while the second one deals with the understanding of the dynamic process of their fabrication. The thi…
Oligo-Miocene lacustrine microbial and metazoan buildups from the Limagne Basin (French Massif Central)
The Limagne Basin (French Massif Central) is an extensive continental lacustrine system accommodating microbial and metazoan buildups from Chattian to Aquitanian age. A description of these buildups and their associated biotic components in Grand Gandaillat and Crechy quarries provides insights into their spatio-temporal distribution patterns. Flats, cauliflowers, domes, cones and coalescent columnar morphologies have been identified with a main laminated mesofabric and laminated, columnar, filamentous and caddisfly-coated microfabrics. Two low-gradient margin models emerged based on the changes in the distribution, morphology and size of the microbial and metazoan-rich deposits through tim…
Experimental modeling of bacterially-induced Ca carbonate precipitation: new insights on possible mechanisms.
The contribution of microorganisms, particularly bacteria, in carbonate mineral formation, the main natural processes controlling CO2 level in the atmosphere, has played an important role since the Archean Eon. In this study we review our recent experimental work on CaCO3 precipitation induced by two anoxygenic phototrophic bacteria (APB), Rhodovulum steppense A-20sT and Rhodovulum sp. S-17-65, and by cyanobacteria Gloeocapsa sp. f-6gl. These bacteria are representatives of two important groups of photosynthetic organisms present at the Earth surface both in the past and at the present times. The mechanisms of organomineralization deriving from APB and cyanobacteria activities are drastical…