David C Gillan

Université de Mons, Mons, Walloon Region, Belgium

Are you David C Gillan?

Claim your profile

Publications (47)162.23 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the study was to understand the effect of a long term metal exposure (110 years) on sediment microbial communities. Two freshwater sites, Férin and MetalEurop, differing by one order of magnitude in metal levels (MetalEurop: 3218 mg Zn kg–1; 913 mg Pb kg–1) were compared by shotgun metaproteogenomics. A total of 69–118 Mpb of DNA and 943–1241 proteins were obtained. PhymmBL analysis of the DNA sequences indicated that the phylogenetic profile was similar in both stations and that β-Proteobacteria were dominant. However, subtle but significant changes were observed for some bacteria: e.g., Pseudomonas (+0.4%), Leptothrix (–0.4%), Thiobacillus (+0.36%), Acidovorax (+0.48%). Using the STAMP software, the two communities were found to be functionally very similar. However, significant genetic differences (10–6 < P < 10–3) were observed for three SEED categories: synthesis of exopolymeric substances, virulence and defense mechanisms (including czcA metal efflux genes), and elements involved in horizontal gene transfer. The CzcA protein was found by metaproteomics in MetalEurop but levels were too low to allow comparisons. It is concluded that bacterial communities in freshwater sediments may adapt to high metal levels without broad changes in the structure of the population.
    Environmental Microbiology 09/2014; · 6.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Seasonal variation in trace metal contamination in surface sediments was studied through high resolution profiles assessed monthly by DGT probes in muddy sediments of the North Sea. General parameters such as pH, temperature, dissolved oxygen and sulfides were also recorded to estimate their role in the speciation of trace metals. Experimental data were included in a thermodynamic equilibrium model to calculate major (geo)chemical processes at the water–sediment interface and to predict the fate of the trace metals in case of (physico-)chemical changes. Results showed lowest Fe, Co, Ni and Cd concentrations in summer, which are most probably due to the very high sulfide concentrations according to our theoretical calculations. Cu and Pb behavior were found to be less influenced by sulfides, since they are also strongly associated to organic matter. The whole set of results clearly indicated that metal speciation in these sediments is controlled by sulfides and OM contents.
    Marine Pollution Bulletin. 01/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: In bacteria a metal may be defined as bioavailable if it crosses the cytoplasmic membrane to reach the cytoplasm. Once inside the cell, specific metal resistance systems may be triggered. In this research, specific metal resistance genes were used to estimate metal bioavailability in sediment microbial communities. Gene levels were measured by quantitative PCR and correlated to metals in sediments using five different protocols to estimate dissolved, particle-adsorbed and occluded metals. The best correlations were obtained with czcA (a Cd/Zn/Co efflux pump) and Cd/Zn adsorbed or occluded in particles. Only adsorbed Co was correlated to czcA levels. We concluded that the measurement of czcA gene levels by quantitative PCR is a promising tool which may complement the classical approaches used to estimate Cd/Zn/Co bioavailability in sediment compartments.
    Environmental Pollution 01/2014; 189:143–151. · 3.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pseudomonas bacteria are ubiquitous Gram-negative and aerobic microorganisms that are known to harbor metal resistance mechanisms such as efflux pumps and intracellular redox enzymes. Specific Pseudomonas bacteria have been quantified in some metal-contaminated environments, but the entire Pseudomonas population has been poorly investigated under these conditions, and the link with metal bioavailability was not previously examined. In the present study, quantitative PCR and cell cultivation were used to monitor and characterize the Pseudomonas population at 4 different sediment sites contaminated with various levels of metals. At the same time, total metals and metal bioavailability (as estimated using an HCl 1M extraction) were measured. It was found that the total level of Pseudomonas, as determined by qPCR using two different genes (oprI and the 16S rRNA gene), was positively and significantly correlated with total and HCl-extractable Cu, Co, Ni, Pb and Zn, with high correlation coefficients (>0.8). Metal-contaminated sediments featured isolates of the P. putida, P. fluorescens, P. lutea and P. aeruginosa groups, with other bacterial genera such as Mycobacterium, Klebsiella and Methylobacterium. It is concluded that Pseudomonas bacteria do proliferate in metal-contaminated sediments, but are still part of a complex community.
    Research in Microbiology. 01/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: This work analyzes bacterial diversity of sediments transiting through the gut of Holothuria scabra which is an important bioturbator in tropical shallow waters. This edible holothurian species has a social and economic importance for coastal populations in many developing countries. Bacterial biodiversity was analyzed by sequencing the 16S rRNA of bacterial cultures and clones. DAPI and FISH methods were used to determine and compare the number of bacteria found in the various gut compartments. A total of 116 phylotypes belonging to the γ-Proteobacteria (60.5 %), α-Proteobacteria (24.5 %), Bacteroidetes (6 %), Actinobacteria (2.75 %), Fusobacteria (1.75 %), Firmicutes (1.75 %), Cyanobacteria (1.75 %) and δ-Proteobacteria (1 %) were identified. The number of bacteria is significantly greater (1.5×) in the foregut than in the ambient sediments. The number of bacteria significantly decreases in the midgut and remains stable until defecation. Some γ-Proteobacteria, especially Vibrio, are less affected by digestion than other bacterial taxa. The season has an impact on the bacterial diversity found in the sediments transiting through the gut: in the dry season, γ-Proteobacteria are the most abundant taxon, while α-Proteobacteria dominate in the rainy season. Vibrio is the most frequent genus with some well-known opportunistic pathogens like V. harveyi, V. alginolyticus and V. proteolyticus. Findings show that sediment-associated microbial communities are significantly modified by H. scabra during their transit through the gut which supports the view that holothurians play a substantial role in the structuring of bacterial communities at the sediment–seawater interface.
    Marine Biology 01/2013; 160(12). · 2.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Muddy sediments of the Belgian Continental Zone (BCZ) are contaminated by metals such as Co, As, Cd, Pb, and Ni. Previous studies have suggested that mineralization of phytodetritus accumulating each year on sediments might cause secondary contaminations of the overlying seawater (metal effluxes). The aim of the present research was to investigate these effluxes using a microcosm approach. Muddy sediments were placed in microcosms (diameter: 15 cm) and overlaid by phytodetritus (a mix of Phaeocystis globosa with the diatom Skeletonema costatum). The final suspension was 130.6 mg L(-1) (dw) and the final chlorophyll a content was 750 ± 35 μg L(-1) (mean ± SD). Natural seawater was used for controls. Microcosms were then incubated in the dark at 15°C during 7 days. Metals were monitored in overlying waters and microbial communities were followed using bacterial and nanoflagellate DAPI counts, thymidine incorporation, community level physiological profiling (CLPP) and fluorescein diacetate analysis (FDA). Benthic effluxes observed in sediments exposed to phytodetritus were always more elevated than those observed in controls. Large effluxes were observed for Mn, Co and As, reaching 1084 nmol m(-2)day(-1) (As), 512 nmol m(-2)day(-1) (Co), and 755 μmol m(-2)day(-1) (Mn). A clear link was established between heterotrophic microbial activity and metal effluxes. The onset of mineralization was very fast and started within 2h of deposition as revealed by CLPP. An increased bacterial production was observed after two days (8.7 mg Cm(-2)day(-2)) and the bacterial biomass appeared controlled by heterotrophic nanoflagellates. Calculations suggest that during phytoplankton blooms the microbial activity alone may release substantial amounts of dissolved arsenic in areas of the BCZ covered by muddy sediments.
    Science of The Total Environment 03/2012; 419:98-108. · 3.26 Impact Factor
  • Source
    Environmental Chemistry. 01/2012; 9(1):41-47.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Our current view about the relationship between metals and bacteria in marine sediments might be biased because most studies only use ex situ approaches to quantify metals. The aim of the present research was to compare ex situ and in situ methods of metal measurement (DET and DGT--diffusive equilibration or diffusive gradients in thin-films) and relate the results with two commonly used microbiological variables (bacterial biomass and bacterial diversity as revealed by DGGE). No previous studies have used such in situ approaches in microbial ecology. For biomass and most of the investigated trace metals (Ag, Cd, Sn, Cr, Ni, Cu, Pb, and Al) no significant correlations were found. The exceptions were Fe, Mn, Co, and As which behave like micronutrients. For bacterial diversity, no relevant relationships were found. We conclude that in situ methods are more adapted tools for microbial ecologists but that ex situ approaches are still necessary.
    Marine pollution bulletin 12/2011; 64(2):353-62. · 2.63 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Marine biofilms were established on glass beads with or without deliberate pre-exposure to LAS (20 μg/L) in Spain (Cadiz) and Sweden (Kristineberg). The ability of each community to mineralize LAS (100 μg/L) was then assessed in biometers at four experimental temperatures (between 6 and 21°C). Genetic diversity and biomass of the biofilms were assessed by genetic fingerprinting (DGGE) and direct bacterial counts. With biofilms from Sweden, where LAS was not detected in seawater (n = 3), deliberate pre-exposure to LAS resulted in lower genetic diversity and higher mineralization rate constant; however, with biofilms from Spain, where 6.4 ± 3.9 μgLAS/L (n = 3) was measured during the colonization, pre-exposure did not affect the bacterial community. Bacterial acclimation therefore appeared to have been induced at environmental concentrations < 6 μgLAS/L. Environmental pre-exposure was not a pre-requisite for featuring the full consortia of LAS degraders in the biometers. The mineralization rate was described using an Arrhenius equation at experimental temperatures within the typical annual range; however, they departed from this model below this range.
    Ecotoxicology and Environmental Safety 03/2011; 74(5):1250-6. · 2.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Black, ferromanganese deposits are known from various environments in the subsurface or the deep ocean. A few studies ascribed metal oxidation and accumulation in these environments to biological processes such as chemolithotrophic bacterial metab-olism. Ferromanganese deposits from the Azé Cave, Saône-et-Loire, were investigated using various techniques to clarify their composition and address their formation. Mineralogical analysis using XRD, RAMAN and FTIR spectroscopy showed predomi-nant manganese and iron oxi-hydroxides with minor silt-and clay-sized detrital minerals. These oxides, which include hollandite, birnessite, romanechite and goethite, are poorly-crystallized and therefore difficult to characterize. Biological analysis confirmed the presence of filamentous and coccoidal microorganisms through optical and electronic microscopy and, with a higher level of confidence, DAPI stains. However, DNA extraction failed due to either inefficient conservation of the sample or excessive selectivity of the PCR amplification, which was designed for bacterial DNA only. Further research is thus needed for identifying the microbiota. Nevertheless, the occurrence of living or dormant microorganisms and typical microbial textures such as microstromatolites in the black deposit strongly suggests that biological processes either passively or actively promoted manganese accumulation in the Azé Cave. Chemolithotrophic bacterial metabolism was previously suggested by other researchers in similar cave deposits. The apparent opposite trend between speleothem and Mn-rich microbial mat development in the Azé Cave suggests that oxygen concentration in the cave atmosphere may be a key factor for the formation of these deposits. Similarily to iron microbial mats, the manganese deposits would preferentially develop under dysaerobic conditions, which can provide valuable information on the cave environment in the past and fluctuation thereof.
    Quaternaire 01/2011; 4:297-305. · 1.09 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Eight iron (Fe) isotopic compositions of iron deposits in biofilms and granules found in two recent burrowing marine invertebrates (the sea urchin ­Echinocardium cordatum and the bivalve Montacuta ferruginosa) were obtained by Multiple-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). δ56Fe values ranged between –1.78‰ and −0.74‰. The lightest δ56Fe is ­associated with the iron granules in the intestinal wall of E. cordatum and may be due to the abiotic oxidation of source Fe(II) with an isotopic composition reflecting that of light reduced Fe in sediment porewater. This lightest value could represent the best value for the pristine value. Fe in the biofilms was typically heavier by up to +1‰, mean ∼ +0.7‰. These results are compared with Fe isotopic composition of 17 Jurassic limestones from the Rosso Ammonitico Veronese (Italy) containing red and gray hemipelagic facies. The red facies show clear evidence of iron bacteria and fungi, which are interpreted as a possible equivalent of the iron microbial communities associated with the recent organisms. Pronounced Fe isotope fractionation was observed in the Jurassic red hardground levels and in the more condensed red facies where bacteria and fungi lived and have accumulated, with values ­typically lighter by −1‰ than the gray facies where microorganisms were absent. This fractio­nation probably involved the passive accumulation of originally light porewater Fe in the exopolymeric substances (EPS) produced by filamentous bacteria, thereby favoring heavier Fe isotopes. Alternating stages of oxidation Fe(II)/Fe(III) occurred near the sediment/water interfaces as a consequence of microenvironmental changes in the marine porewaters and caused the red/gray facies interlayering. The comparison of the Fe isotopic compositions of the “biominerals” in the recent organisms and in the iron minerals of the red and gray Jurassic facies suggests an isotopic biofractionation of at least ∼+0.7‰. Both studied organisms (the sea urchin and the bivalve) thrive in similar microenvironmental conditions as the ­microorganisms of the condensed red facies. Their Fe isotope compositions are the same, as is the range of the probable biofractionation. KeywordsIron isotopes-Microbial mediation-Italian Jurassic Rosso Ammonitico-Recent sea urchins and bivalves
    01/2011: pages 651-673; , ISBN: 978-94-007-0397-1_29
  • [Show abstract] [Hide abstract]
    ABSTRACT: The “Schisto-Calcaire Subgroup” is a muddy predominantly subtidal shelf succession that crops in the West Congolian Belt. The approximately 300-m-thick CI (Bas-Congo) and approximately 20-m-thick SCIII (Gabon) series were deposited in a very shallow marine evaporitic environment. The evidence for this interpretation includes sedimentology of dolomite and sulfate minerals and oxygen isotopes. Cyanobacteria (probable Oscillatorians) formed mats on the inland marshes fringing ponds of channeled belts. In Gabon, they are associated with abundant domal stromatolites deposited in shallow to lower intertidal settings. While diagenetic overprints (dolomicrosparitization, sulfate growth, silica replacement) may be significant, several microbial laminar mudstones retained their original fabric. SEM analysis revealed well-preserved three-dimensional (3D) cyanobacterial communities associated with the stromatolites. During progressive lithification in the upper part of shallowing-upward evaporitic sequences, the stromatolites constituted a favorable substrate which has been invaded and colonized by probable fungal hyphae. These produced characteristic features that have been reproduced in vitro in experiments. KeywordsStable isotopes (C, O)-Bacterial mats-Precambrian-Paleoenvironments-Microfacies-Diagenesis
    12/2010: pages 43-63;
  • [Show abstract] [Hide abstract]
    ABSTRACT: An innovative biodegradation test system was developed in order to fill the current gap for cost effective and environmentally relevant tools to assess marine biodegradability. Glass beads were colonized by a biofilm in an open flow-through system of seawater with continuous pre-exposure to Linear Alkylbenzene Sulfonate (LAS) (20 microg/L). Thereafter, such colonized beads were added as inoculum in different test systems. [(14)C]-LAS (5-100 microg/L) was added and primary and ultimate biodegradation were assessed. The bacterial density collected on the beads (10(9) bact./mL beads) was ca. 3 orders of magnitude higher than the typical seawater content. The LAS mineralization lag phase duration decreased from 55 to <1 days and the mineralization extent increased from 53 to 90% as the colonized beads volume increased from 10 to 275 mL. This is the first demonstration of marine bacteria's ability to mineralize LAS. On the opposite, less than 13% LAS was mineralized in seawater only. The colonized beads possibly enhanced the probability to encounter the full degraders' consortium in a low volume of seawater (100 mL).
    Environment international 05/2009; 35(6):885-92. · 6.25 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: High resolution profiles of trace elements (Fe, Mn, Co, As, Cu, Cr, Ni and Pb) were assessed using the DET (Diffusive Equilibrium in Thin films) and DGT (Diffusive Gradients in Thin films) techniques in silty, organically enriched, sub-tidal sediments of the Belgian coast during late winter and spring 2008. The general chemical properties of the sediments such as dissolved oxygen, pH, Eh and sulfide profiles, controlling precipitation/ mobilization reactions, were determined with electrodes (pH and Eh) and microelectrodes (oxygen) and AgIDGT probes (sulfide). Most trace elements show subsurface maxima and low concentrations beneath 8 cm of depth. The main physicochemical parameters controlling the vertical concentration profiles are dissolved oxygen and redox potential in the surface sediment and sulfide in the deeper sediment layers. Thermodynamic equilibrium calculations have been carried out verifying which solid phases can explain the dissolved trace metal concentrations. Seasonal variations of trace elements have been observed during the sampling period and sedimentation of fresh particulate organic matter (POM) derived from phytoplankton blooms appear to be the main cause of this temporal variability. Flux calculations based on DGT profiles (these fluxes are minimum ones) show that exchange fluxes of trace metals in February are slightly higher than in April. In addition, "DGT pistons" were deployed at the sediment water interface (SWI) to accumulate labile ions from below. This way all labile ions, binding onto the DGT Chelex resin, are pumped out of the porewaters and the solid sediment phase (only the mobile fraction). These results are a direct estimation of the amount of trace elements that can be released from the upper sediment to the water column (in the range of 4.4·10<sup>-5</sup> to 0.10 mmol·m<sup>-2</sup>·d<sup>-1</sup> for Co, Pb, Cr, As, Cu, Ni, Fe and Mn).
    01/2009;
  • Pierre T. Becker, David C. Gillan, Igor Eeckhaut
    [Show abstract] [Hide abstract]
    ABSTRACT: The bacterial community associated with skin lesions of the sea urchin Tripneustes gratilla was investigated using 16S ribosomal RNA gene cloning and fluorescent in situ hybridization (FISH). All clones were classified in the Alphaproteobacteria, Gammaproteobacteria and Cytophaga–Flexibacter–Bacteroides (CFB) bacteria. Most of the Alphaproteobacteria were related to the Roseobacter lineage and to bacteria implicated in marine diseases. The majority of the Gammaproteobacteria were identified as Vibrio while CFB represented only 9% of the total clones. FISH analyses showed that Alphaproteobacteria, CFB bacteria and Gammaproteobacteria accounted respectively for 43%, 38% and 19% of the DAPI counts. The importance of the methods used is emphasized.
    Journal of Invertebrate Pathology 01/2009; · 2.67 Impact Factor
  • Source
    Pierre Becker, David C Gillan, Igor Eeckhaut
    [Show abstract] [Hide abstract]
    ABSTRACT: The microbiota of the body wall lesions of the echinoid Tripneustes gratilla, initiated by the grazing action of the parasitic gastropod Vexilla vexillum, was investigated with a pluridisciplinary approach. Parasitised sea urchins showed body wall lesions strongly infected by bacteria that progressed through the test and reached the coelomic cavity after ca. 1 mo. We report here on the bacterial community observed in lesions of echinoids collected in situ and on the bacteria that successively appeared during laboratory experiments. Two Alphaproteobacteria, a CFB (Cytophaga-Flavobacterium-Bacteroides) bacterium, 3 Vibrio species and Exiguobacterium aestuarii were identified in the field-collected lesions by 16S rDNA sequencing. The last 4 bacteria were cultured and each induced the disease when inoculated on scalpel-made wounds, with 100% of the individuals infected within 2 d. Scalpel-induced scarifications tended to heal within 3 wk, while gastropod-induced lesions evolved into disease, suggesting a role of Vexilla vexillum in the development of the infection. Denaturing gradient gel electrophoresis (DGGE) and sequencing suggest that (1) bacteria associated with healthy integument were not present in the lesions and were thus not responsible for their infection, (2) Alphaproteobacteria with close phylogenetic affiliation with other bacteria involved in several diseases affecting marine invertebrates were present, and (3) these Alphaproteobacteria were present from the beginning of the infection and appeared earlier in the infection than other bacteria such as CFB bacteria.
    Diseases of Aquatic Organisms 09/2007; 77(1):73-82. · 1.73 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Shallow marine benthic communities around Antarctica show high levels of endemism, gigantism, slow growth, longevity and late maturity, as well as adaptive radiations that have generated considerable biodiversity in some taxa. The deeper parts of the Southern Ocean exhibit some unique environmental features, including a very deep continental shelf and a weakly stratified water column, and are the source for much of the deep water in the world ocean. These features suggest that deep-sea faunas around the Antarctic may be related both to adjacent shelf communities and to those in other oceans. Unlike shallow-water Antarctic benthic communities, however, little is known about life in this vast deep-sea region. Here, we report new data from recent sampling expeditions in the deep Weddell Sea and adjacent areas (748-6,348 m water depth) that reveal high levels of new biodiversity; for example, 674 isopods species, of which 585 were new to science. Bathymetric and biogeographic trends varied between taxa. In groups such as the isopods and polychaetes, slope assemblages included species that have invaded from the shelf. In other taxa, the shelf and slope assemblages were more distinct. Abyssal faunas tended to have stronger links to other oceans, particularly the Atlantic, but mainly in taxa with good dispersal capabilities, such as the Foraminifera. The isopods, ostracods and nematodes, which are poor dispersers, include many species currently known only from the Southern Ocean. Our findings challenge suggestions that deep-sea diversity is depressed in the Southern Ocean and provide a basis for exploring the evolutionary significance of the varied biogeographic patterns observed in this remote environment.
    Nature 06/2007; 447(7142):307-11. · 38.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Concentrations of the essential trace metals copper and zinc were measured in the pyloric caeca of female Coscinasterias muricata sampled from Port Phillip Bay, Victoria, Australia at monthly intervals for 15 months. Results indicate that the concentrations of these metals appear to be regulated by the reproductive cycle. Peaks in zinc concentration occurred simultaneously with peaks in progesterone concentration in the pyloric caeca. These findings suggest that zinc plays a role in gametogenesis and ovarian development. Fluctuations in pyloric caeca copper concentration appear inversely related to the pyloric caecal index and associated with oocyte diameter, indicative of a role for this metal in oogenesis. The levels of cytosolic heat stable low molecular mass (LMM) proteins were examined throughout the sampling period. Heat stable LMM proteins (metallothionein-like) of 12 kDa and 7.5 kDa (apparent molecular mass) and the concentrations of copper appear to be related; although the exact nature of these proteins remains unknown. No such relationship was observed between the levels of heat stable LMM proteins and zinc.
    Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 05/2007; 145(3):449-56. · 2.71 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Shallow marine benthic communities around Antarctica show high levels of endemism, gigantism, slow growth, longevity and late maturity, as well as adaptive radiations that have generated considerable biodiversity in some taxa 1 . The deeper parts of the Southern Ocean exhibit some unique environmental features, including a very deep continental shelf 2 and a weakly stratified water column, and are the source for much of the deep water in the world ocean. These features suggest that deep-sea faunas around the Antarctic may be related both to adjacent shelf com-munities and to those in other oceans. Unlike shallow-water Antarctic benthic communities, however, little is known about life in this vast deep-sea region 2,3 . Here, we report new data from recent sampling expeditions in the deep Weddell Sea and adjacent areas (748–6,348 m water depth) that reveal high levels of new biodiversity; for example, 674 isopods species, of which 585 were new to science. Bathymetric and biogeographic trends varied between taxa. In groups such as the isopods and polychaetes, slope assemblages included species that have invaded from the shelf. In other taxa, the shelf and slope assemblages were more distinct. Abyssal faunas tended to have stronger links to other oceans, particularly the Atlantic, but mainly in taxa with good dispersal capabilities, such as the Foraminifera. The isopods, ostracods and nematodes, which are poor dispersers, include many species cur-rently known only from the Southern Ocean. Our findings chal-lenge suggestions that deep-sea diversity is depressed in the Southern Ocean and provide a basis for exploring the evolutionary significance of the varied biogeographic patterns observed in this remote environment. Although animal communities inhabiting shallow marine benthic environments around Antarctica, notably parts of McMurdo Sound and the Peninsula region, are well known, there have been few studies of the deep-water faunas in the adjacent Southern Ocean. The ANDEEP (Antarctic benthic deep-sea biodiversity: colonization history and recent community patterns) project was designed to fill this knowledge vacuum 4 . Between 2002 and 2005, we undertook three expeditions in the deep Weddell Sea and adjacent areas aboard the German research vessel Polarstern. Biological collections and data on environmental and seafloor characteristics were obtained from diverse settings, including continental slope, rise, abyssal plain, trench floor, channel levees and adjacent to fracture zones, and from water depths between 774 and 6,348 m (Fig. 1; Supplementary Discussion; Supplementary Tables 1, 2; Supplementary Figs 1, 2). This material has greatly improved our knowledge of the biodiversity of benthic communities in the deep Southern Ocean and enabled us to test ideas about large-scale biogeographic and other macroeco-logical patterns 5 among deep-water faunas. The richness of species inhabiting deep-sea sediments was first demonstrated during the 1960s 6,7 . Since then, scientists have sought to understand the mechanisms that maintain these high levels of benthic diversity at local 8 and regional 9 scales. We analysed species assemblages in ANDEEP samples across a range of taxonomic groups, representing the meiofauna, macrofauna and megafauna (Fig. 2) and found substantial levels of unrecorded biodiversity (see Supplementary Material). The Foraminifera were represented by 158 live species, including 72 monothalamous species, most of them undescribed. The nematodes belonged to typical cosmopolitan deep-sea genera (Supplementary Fig. 3), but more than half of the 57
    Nature 04/2007; 447:231-114. · 38.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Despite the ecological and evolutionary importance of echinoderms, very little is known about the immune mechanisms in this group especially regarding humoral immunity. In this paper, we screened for proteins putatively involved in immunity in the common European seastar Asterias rubens using a mass spectrometry-based proteomic approach. Two proteins showed striking sequence similarities with peptidoglycan recognition proteins (PGRPs). The two seastar proteins were identified as a single protein, termed PGRP-S1a, occurring in two forms in the coelomic plasma, one of 20kDa and another of 22kDa. We also cloned and sequenced a second member of the PGRP family, termed PGRP-S2a. It has a calculated molecular mass of 21.3kDa and is expressed in circulating phagocytes. Both the S1a-cDNA from coelomic epithelium RNA and the S2a-cDNA from phagocytes code for the amino acid residues necessary for peptidoglycan degradation. PGRP-S1a did not affect the phagocytic activity of seastar immune cells towards Micrococcus luteus but inhibited their production of reactive oxygen species (ROS). A recombinant, His-tagged, PGRP-S2a degrades peptidoglycan and increases the phagocytosis of M. luteus cells by seastar phagocytes.
    Developmental & Comparative Immunology 02/2007; 31(8):790-804. · 3.24 Impact Factor

Publication Stats

555 Citations
162.23 Total Impact Points

Institutions

  • 2007–2014
    • Université de Mons
      • • Department of Proteomics and Microbiology
      • • Department of Biology
      Mons, Walloon Region, Belgium
  • 1998–2009
    • Université Libre de Bruxelles
      • • Laboratory of Biology (BIO)
      • • Department of Earth and Environment Sciences
      Bruxelles, Brussels Capital Region, Belgium
  • 2004
    • Max Planck Institute for Marine Microbiology
      Bremen, Bremen, Germany