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Biologically-controlled mineralization in the hypercalcified sponge Petrobiona massiliana (Calcarea, Calcaronea)
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Hypercalcified sponges, endowed with a calcium carbonate basal skeleton in addition to their spicules, form one of the most basal metazoan group engaged in extensive biomineralization. The Mediterranean species Petrobiona massiliana was used to investigate biological controls exerted on the biomineralization of its basal skeleton. Scanning and transmission electron microscopy (SEM, TEM) confirmed that basopinacocytes form a discontinuous layer of flattened cells covering the skeleton and display ultrastructural features attesting intense secretory activity. The production of a highly structured fibrillar organic matrix framework by basopinacocytes toward the growing skeleton was highlighted both by potassium pyroantimonate and ruthenium red protocols, the latter further suggesting the presence of sulfated glycosaminoglycans in the matrix. Furthermore organic material incorporated into the basal skeleton was shown by SEM and TEM at different structural levels while its response to alcian blue and acridine orange staining might suggest a similar acidic and sulfated chemical composition in light microscopy. Potassium pyroantimonate revealed in TEM and energy electron loss spectroscopy (EELS) analysis, heavy linear precipitates 100–300 nm wide containing Ca2+ and Mg2+ ions, either along the basal cell membrane of basopinacocytes located toward the decalcified basal skeleton or around decalcified spicules in the mesohyl. Based on the results of the previous mineralogical characterization and the present work, an hypothetical model of biomineralization is proposed for P. massiliana: basopinacocytes would produce an extracellular organic framework that might guide the assemblage of submicronic amorphous Ca- and Mg-bearing grains into higher structural units.
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RBINS Staff Publications
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Biology and fisheries of the spotted flounder (Citharus linguatula) caught by multiple gears with partial spatiotemporal overlaps
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Obtaining data to study fish biology can be a challenge if a stock is fished by a variety of gears with different effort units and different selectivity, particularly if these gears only partially overlap in space and time. In this work, we attempted to study the biology of the spotted flounder Citharus linguatula in the Patraikos Gulf and the adjacent central Ionian Sea (eastern Mediterranean) and to evaluate the current fisheries management. We characterized age composition and growth, length-at-maturity, and catch-perunit- effort (CPUE) of spotted flounder from the catches of bottom trawls, gillnets and trammel nets for the period autumn 2013–2014. Variation of fish total length, gonadosomatic index, hepatosomatic index and condition factor was analyzed using generalized additive models (GAMs) with regard to sex, date, fishing gear and depth.We also modeled CPUE fluctuations of each gear by date, depth, longitude and latitude using GAMs. Fish age ranged from 1 to 5 years. A slightly allometric growth was documented with females attaining larger sizes than males. Length-at-maturity was 163mm for females and 169mm for males. The seasonal change of gonad maturity stages and the gonadosomatic index indicated spawning in late summerautumn. Changes in length frequencies indicated that recruitment to the fisheries occurred in late springearly winter in shallow depth (<40 m). The catch composition of trawls and the CPUE model results suggested that the selectivity of this gear should be regulated to reduce catching immature individuals of spotted flounder. The results further indicated that the seasonal trawl closure of the Patraikos Gulf contributes to reduce catching juveniles.
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RBINS Staff Publications 2017
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Biomimetic and bio-inspired uses of mollusc shells
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RBINS Staff Publications 2016
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Biomineralization in living hypercalcified demosponges: Toward a universal mechanism?
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Massive skeletons of living hypercalcified sponges, representative organisms of basal Metazoa, are uncommon models to improve our knowledge on biomineralization mechanisms and their possible evolution through time. Eight living species belonging to various orders of Demospongiae were selected for a comparative mineralogical characterization of their aragonitic or calcitic massive basal skeleton. The latter was prepared for scanning and transmission electron microscopy (SEM and TEM), selected-area electron diffraction (SAED) and X-ray diffraction (XRD) analyses. SEM results indicated distinctive macro- and micro-structural organizations of the skeleton for each species, likely resulting from a genetically dictated variation in the control exerted on their formation. However, most skeletons investigated shared submicron to nano-scale morphological and crystallographical patterns: (1) single-crystal fibers and bundles were composed of 20 to 100nm large submicronic grains, the smallest structural units, (2) nano-scale likely organic material occurred both within and between these structural units, (3) {110} micro-twin planes were observed along aragonitic fibers, and (4) individual fibers or small bundles protruded from the external growing surface of skeletons. This comparative mineralogical study of phylogenetically distant species brings further evidence to recent biomineralization models already proposed for sponges, corals, mollusks, brachiopods and echinoderms and to the hypothesis of the universal and ancestral character of such mechanisms in Metazoa.
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RBINS Staff Publications
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Biostratigraphy of the Danian/Selandian transition in the southern Tethys. Special reference to the Lowest Occurrence of planktic foraminifera Igorina albeari.
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RBINS Staff Publications
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Biotic and abiotic determinants of the formation of ant mosaics in primary Neotropical rainforests
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RBINS Staff Publications 2019
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Biotic impact of Eocene thermal maximum 2 in a shelf setting (Dababiya, Egypt).
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The Paleocene-Eocene thermal maximum (PETM) initiated a global biotic event with major evolutionary impacts. Since a series of minor δ13C and δ18O excursions, indicative of hyperthermals, now appears to characterize early Eocene climate, it remains to be investigated how the biosphere responded to these warming events. We studied the Esna Formation at Dababiya (Nile Basin, Egypt), in order to identify Eocene thermal maximum 2 (ETM-2) and to evaluate the foraminiferal and ostracode patterns. The studied interval generally consists of gray-brown marls and shales and is interrupted by a sequence of deviating lithologies, representing an early Eocene Egyptian environmental perturbation that can be linked to ETM-2. The ETM-2 interval consists of brownish shales (bed 1) to marls (bed 2) at the base that grade into a foraminifera-rich chalky limestone (bed 3) at the top. This conspicuous white limestone bed forms the base of the Abu Had Member. A distinct negative δ13C excursion of approximately 1.6‰ is recorded encom- passing this interval and a second negative δ13C shift of 1‰ occurs 5 m higher. These two isotope events are situated respectively in the basal and lower part of the calcareous nannoplankton zone NP11 and appear to correlate with the H1 and H2(?) excursions observed in the deep-sea records. The lower δ13C excursion is associated with benthic foraminiferal and ostracode changes and settlement of impoverished anomalous foraminiferal (planktic and benthic) assemblages, indicating a transient environmental anomaly, disrupting the entire marine ecosystem during ETM-2. Our observations indicate some similarities between the sedimentary and biotic expressions of ETM-2 and the PETM at Dababiya, pointing to similar processes operating in the Egyptian Basin during these global warming events.
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RBINS Staff Publications
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Bird bones from Trou de Chaleux and the human exploitation of birds during the late Magdalenian in Belgium
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The Trou de Chaleux is a cave site located in Belgium. It delivered a rich late Magdalenian material culture constituted mainly of lithic artefacts but also including bone industries and figurative art. This paper presents the results of the analysis of the large collection of bird remains recovered by E. Dupont in 1865, which was yet unstudied from taphonomical and archaeozoological perspectives. In addition to the taxonomic identification, surface alterations were investigated based on a macro- and microscopic analysis, including an analysis of wear traces and elementary composition. Special attention is devoted to the presence of human modifications such as disarticulation or butchering marks, traces of heating, presence of colourants and traces of bone working. The taphonomic history of the bird assemblage is reconstructed and the use of birds by humans characterized, as well as their importance in past human activities. We also discuss evidence for seasonal exploitation and for reconstructing the local environment and integrate our results with evidence from other Magdalenian assemblages from north-western Europe. At Trou de Chaleux, birds were used for food, as raw material for bone working and for symbolic purposes. The exploitation of avian products was intense, and species have been used for several purposes such as the raven and snowy owl having been exploited both for food and for symbolic reasons. Large bird bones were used as raw material to produce artefacts, but the use-wear analysis did not evidence unambiguous traces related to the use of the objects produced. Despite several limiting factors, the bird material from Trou de Chaleux considerably increases the knowledge of past human exploitation of birds during the late Magdalenian in north-western Europe.
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RBINS Staff Publications 2020
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Bird remains from Late Medieval and Postmedieval sites in Brussels, Belgium
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RBINS Staff Publications
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Black adzes in the Early Neolithic of Belgium. Contribution of the Raman microspectrometry and petrography in the characterization and sourcing
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Ancient Neolithic (Linear Pottery Culture) adzes originate from settlements and workshops accompany the neolithization of Belgium. They are made from a wide range of extraregional lithic raw materials such as metamorphic green rocks (amphibolite) and black volcanic rocks (‘basalt’) beside more local or regional raw material as flints, light-coloured (sedimentary and lightly metamorphic) quartzites and fine-grained black rocks. Another material source included black lydites (Cambrian nodular phtanite of Céroux-Mousty and Lower Namurian banded phtanites) and dark grey Lower Namurian silicified sandstones called ‘Micaceous sandstones of Horion-Hozémont’. The discovery of the workshop of Noir Fontaine near the city of Liège in the 1970s and 1980s provides exceptional assemblage available for updating analytical studies. This research focuses on the multi-scale characterization, the discrimination and sourcing of the different types of fine-grained black materials composing Ancient Neolithic adzes found in Belgium. Their black colour results from finely dispersed organic matter, but the absence of palynomorphs does not allow a biostratigraphic ascription. Additional petrographical analyses (Optical Petrography - OP, Scanning Electronic Microscopy - SEM), X-ray diffraction (XRD), chemical analyses (Energy Dispersive Spectroscopy - EDS) and measuring the degree of graphitization of the organic matter through Raman microspectrometry have been decisive in identifying the geological and geographical provenances by comparing the acquired results with geological reference samples collected in the field or through reference collections. The distribution of the different black coloured rocks shows that Cambrian lydites are coming from a very restricted area and were preferred to other more local rock sources.
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RBINS Staff Publications 2021
