Search

Stražnjoškržnjaci srodnih vrsta Aplysia punctata i A. fasciata (Gastropoda, Opisthobranchia, Anaspidea) pojavljuju se istovremeno na opsežnim infralitoralnim dnima obalnih područja Sredozemlja i Jadrana. Tijekom rasta i razvoja ličinke spiralna kućica potpuno obuhvaća i štiti meko tijelo. Nakon preobrazbe veligera vanjska kućica postaje unutarnja i reducira se do jednostavnog konkavnog štita iznad meke utrobe. Skenirajuća elektronska mikroskopija (SEM), infracrvena spektroskopija s Fourierovom transformacijom (FTIR) i difrakcija X‐zraka (XRD) su metode korištene za određivanje morfoloških, fizikalnih, strukturnih i kristalografskih značajki "odraslih" kućica obiju vrsta. Istovremeno, u uzorcima je mjerena aktivnost ugljikove anhidraze (CA), te su određivane molekularne značajke primjenom proteomiksa i imunohistološke lokalizacije nizom specifičnih protutijela. Odrasla kućica vrste A. punctata ima dva organska sloja, između kojih se nalazi kalcificirani sloj sa dominantnim aragonitom (71 M %) i feldšparom (19 M %), dok se kućica srodne vrste A. fasciata sastoji gotovo isključivo od kristala aragonita (oko 90 M%). Kristali halita su prisutni vanjskoj i unutarnoj strani kućice kod obje vrste, ali se razlikuju po obliku, orijentaciji i pravcu rasta kristala.

In metazoans, the secretion of skeletal calcium carbonate tissues is regulated by a complex array of extracellular macromolecules, namely proteins and polysaccharides, and sometimes lipids that collectively constitute the skeletal matrix. Because of its ability to ‘sculpt’ the biominerals and to organize spatially crystallites in well-defined microstructures, this matrix has been the focus of several studies. In the last few years, by using proteomics alone or by merging transcriptomics and proteomics, there has been a wealth of information obtained on the protein moieties of the skeletal matrix, in different model and non-model organisms: corals, molluscs, brachiopods, sea urchins. These data allow now establishing preliminary comparisons between the ‘molecular kits’ of different species, from phylum to phylum, and within one given phylum. The obtained data show a remarkable diversity of the proteins involved in mineral deposition, in term of primary structures and of putative functions deduced from in silico sequence analysis. This diversity invites to refine the existing molecular models of mineral deposition and to integrate the role of the calcifying epithelium/calcifying cells facing the front of mineral growth. As illustrated by molluscan nacre on the one hand, and by examples taken from other phyla on the other hand, it appears that ‘similar’ microstructures may emerge from very different protein ‘toolkits’ ; this finding puts into question past attempts to use the matrix for taxonomic purposes. It reveals the astonishing plasticity of the ‘calcifying matrix’ and emphasizes the fact that it is built by the co-option of ancient and recent functions. In a counterintuitive manner, proteomic data suggest that the skeletal matrix is less evolutionary constrained than suspected, exhibits a true ‘evolvability’, while maintaining stable and perennial the associated microstructures.

In metazoans, the secretion of skeletal calcium carbonate tissues is regulated by a complex array of extracellular macromolecules, namely proteins and polysaccharides, and sometimes lipids that collectively constitute the skeletal matrix. Because of its ability to ‘sculpt’ the biominerals and to organize spatially crystallites in well-defined microstructures, this matrix has been the focus of several studies. In the last few years, by using proteomics alone or by merging transcriptomics and proteomics, there has been a wealth of information obtained on the protein moieties of the skeletal matrix, in different model and non-model organisms: corals, molluscs, brachiopods, sea urchins. These data allow now establishing preliminary comparisons between the ‘molecular kits’ of different species, from phylum to phylum, and within one given phylum. The obtained data show a remarkable diversity of the proteins involved in mineral deposition, in term of primary structures and of putative functions deduced from in silico sequence analysis. This diversity invites to refine the existing molecular models of mineral deposition and to integrate the role of the calcifying epithelium/calcifying cells facing the front of mineral growth. As illustrated by molluscan nacre on the one hand, and by examples taken from other phyla on the other hand, it appears that ‘similar’ microstructures may emerge from very different protein ‘toolkits’ ; this finding puts into question past attempts to use the matrix for taxonomic purposes. It reveals the astonishing plasticity of the ‘calcifying matrix’ and emphasizes the fact that it is built by the co-option of ancient and recent functions. In a counterintuitive manner, proteomic data suggest that the skeletal matrix is less evolutionary constrained than suspected, exhibits a true ‘evolvability’, while maintaining stable and perennial the associated microstructures.

Thermocline waters of the tropical southwest Pacific can be traced back to the center of the South Pacific basin and have a potential influence on equatorial surface conditions and on the characteristics of the El Nino Southern Oscillation on decadal timescales. The Solomon Sea is traversed by this influential flow, and therefore is an optimal place for exploring this oceanic connection to the equator. From a high-resolution hydrographic survey at which we applied an inverse box model, we describe the main pathways at the entrance of the Solomon Sea, and more particularly the extremely sharp bend of the western boundary current around the south-east tip of Papua New Guinea. Of the 30 Sv subtropical waters transported into the Coral Sea from the east, above 1300 m, 29 +/- 5 Sv makes its way through the Solomon Sea with a large part transported in a boundary current, at the entrance of the Solomon Sea. Around the south-east tip of Papua New Guinea, the Gulf of Papua Current turns abruptly to the north, in a very sharp bend as it merges into the New Guinea Coastal Undercurrent, on its way, toward the equator. The warm currents transport large amounts of internal energy, with a total of 1.0 +/- 0.3 10(15)W entering the Solomon Sea from the south. Citation: Gasparin, F., A. Ganachaud, C. Maes, F. Marin, and G. Eldin (2012), Oceanic transports through the Solomon Sea: The bend of the New Guinea Coastal Undercurrent, Geophys. Res. Lett., 39, L15608, doi:10.1029/2012GL052575.

Communications et posters du XLVIe congrès annuel de la Société française de chirurgie de la main (Palais des congrès) de la Porte Maillot, Paris, du 16 au 18 de´cembre 2010)

The Mediterranean fan mussel Pinna nobilis secretes a two-layered shell, the external layer of which is composed of long calcite needles, the prisms. The dissolution of these needles with dilute acetic acid release a remarkable assemblage of acidic intracrystalline proteins, among which caspartin, a 17 kDa aspartic acid-rich protein (Marin et al., 2005). A polyclonal antibody was raised againstcaspartin and used for two purposes: -to checjk the thermal stability of caspartin ; to investigate its presence, or the presence of immunologicaly-related protein, in the calcified tissued of several molluscs. In the first case, prisms of Pinna nobilis were heated at different temperatures, for increasing durations. The degradation of caspartin was followed on SDSPAGE and on Western-blot. The experiments show that caspartinis stable at 100 C degree, but degrades more rapidly at 120 C degree. For the second purpose, EDTA-soluble matrices were extracted from numerous molluscs shells including bivalves, gastropods and cephalopods. These matrices were subsequently tested by ELISA, dot-blot, and Western-blot, to check the presence of caspartin or immunologically-related proteins. The pattern does not follow the phylogeny of molluscs nor it is correlated with the shell microstructural pattern.

Tahiti’s pearl farming industry plays a major socio-economic role in French Polynesia. In an increasingly competitive market where the production of high quality pearls becomes essential, research can help secure and ensure sustainable production. In that context, Ifremer, in close collaboration with the “direction des resources marines” (French Polynesian government agency) has developed research projects on the “sustainable development of pearl farming”. This program is organized along 3 axes: (1) understanding the animal physiology and initiating a genetically selective breeding program of donor oysters; (2) understanding pearl oyster larvae dispersal and recruitment; (3) understanding the molecular mechanisms underlying biomineralization processes during shell and pearl formation. It is in this frame that we have developed a highthroughput Expressed Sequence Tags pyrosequencing program on the calcifying mantle, combined with proteomic analyses of the shell and pearl. We analyzed 276738 EST sequences, leading to the constitution of a P. margaritifera mantle transcripts catalogue of 82 sequences potentially involved in biomineralization. Our results provided direct evidence that our ESTs data set covers a large number of the matrix proteins of P. margaritifera. In addition, our proteomic analysis enabled us to retrieve, in silico, all the sequences from P. margaritifera involved in the biomineralization process already published on databases. Integration of these two methods allowed, for the first time, the global composition of calcifying tissue and calcified structures to be examined in tandem.

We updated the agent based Monte Carlo code HERITAGE that simulates human evolution within restrictive environments such as interstellar, sub-light speed spacecraft in order to include the effects of population genetics. We incorporated a simplified -- yet representative -- model of the whole human genome with 46 chromosomes (23 pairs), containing 2110 building blocks that simulate genetic elements (loci). Each individual is endowed with his/her own diploid genome. Each locus can take 10 different allelic (mutated) forms that can be investigated. To mimic gamete production (sperm and eggs) in human individuals, we simulate the meiosis process including crossing-over and unilateral conversions of chromosomal sequences. Mutation of the genetic information from cosmic ray bombardments is also included. In this first paper of a series of two, we use the neutral hypothesis: mutations (genetic changes) have only neutral phenotypic effects (physical manifestations), implying no natural selection on variations. We will relax this assumption in the second paper. Under such hypothesis, we demonstrate how the genetic patrimony of multi-generational crews can be affected by genetic drift and mutations. It appears that centuries-long deep space travels have small but unavoidable effects on the genetic composition/diversity of the traveling populations that herald substantial genetic differentiation on longer time-scales if the annual equivalent dose of cosmic ray radiation is similar to the Earth radioactivity background at sea level. For larger doses, genomes in the final populations can deviate more strongly with significant genetic differentiation that arises within centuries., 41 pages, 2 tables, 15 figures, accepted for publication in JBIS