Quelques considérations sur la place des poissons dans les cycles biogéochimiques, à la lumière de la connaissance de leur arsenal enzymatique digestif

The secretion of chitinases in the digestive tract of most fish species indicate that fishes must play an important role in the recycling of chitin carbon and nitrogen. Some fish species are equipped with ß-1,3 glucanases (or laminarinases) generally secreted by their own intestinal mucosa, and are thus able to take part in the biodegradation of ß-1,3 glucans such as laminarin, leucosin, paramylon, etc. On the contrary, fishes seem to be entirely unable to digest cellulose and thus can hardly play any role in the biogeochemical cycling of this important organic compound

Bioaccumulation de trois insecticides organochlores (lindane, dieldrine et DDT) et des PCB chez plusieurs espèces de fourmis [Hymenoptera-Formicidae] en Belgique

L'étude de l'impact de 3 insecticides organochlorés (lindane, dielrine et DDT) et des PCB sur 5 espèces de fourmis abondamment représentées en Belgique montre qu'en région wallonne, la contamination des fourmis par ces toxiques est générale, mais reste faible quel que soit le milieu considéré. En moyenne, l'ordre de grandeur est de 20 ppb pour le lindane, 4,4 ppb pour le dieldrine, 13,4 ppb pour le pp'DDE, 11,7 ppb pour l'op'DDD, 15,6 ppb pour le pp'DDE 3 métabolites du DDT) et de 200 ppb pour les PCB. Les résultats obtenus ne montrent pas de relation entre le degré de contamination des ouvrières et celui du matériau de construction du nid. De plus, les concentrations en insecticides et en PCB des fourmis et des matériaux de construction des nids ne sont pas significativement différentes dans les milieux agricoles forestiers

Microstructural and biochemical characterization of the nanoporous sucker rings from Dosidicus gigas

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Advanced Materials 21 (2009): 401-406, doi:10.1002/adma.200801197.Recent interest in the development of environmentally benign routes to the synthesis of novel multifunctional materials has resulted in numerous investigations into structure-function relationships of a wide range of biological systems at the ultrastructural, micromechanical, and biochemical levels. While much of this research has concentrated on mineralized structures such as bone, mollusk shells sponge spicules and echinoderm ossicles, there is an equally broad range of animals whose skeletal structures are devoid of mineral components.One such group, the squids (Mollusca: Cephalopoda: Teuthoidea), are remarkable in several aspects. In addition to having an exceptionally well developed brain, sensory systems and skin (for adaptive coloration), these swift agile predators have eight flexible strong arms, two fast extensible tentacles, and strong malleable suckers, all of which are muscular hydrostats.We gratefully acknowledge funding from the Swiss National Science Foundation (AM, PA002–113176 / 1), NIH 5 R01 DE 014672, DANSYNC for supporting the synchrotron experiments, and the Danish Research Councils, as well as partial support (RTH) by DARPA DSO BioDynotics Program (Project N66001-03-C-8043)

Identification of Novel Potential β-N-Acetyl-D-Hexosaminidase Inhibitors by Virtual Screening, Molecular Dynamics Simulation and MM-PBSA Calculations

Chitinolytic β-N-acetyl-d-hexosaminidases, as a class of chitin hydrolysis enzyme in insects, are a potential species-specific target for developing environmentally-friendly pesticides. Until now, pesticides targeting chitinolytic β-N-acetyl-d-hexosaminidase have not been developed. This study demonstrates a combination of different theoretical methods for investigating the key structural features of this enzyme responsible for pesticide inhibition, thus allowing for the discovery of novel small molecule inhibitors. Firstly, based on the currently reported crystal structure of this protein (OfHex1.pdb), we conducted a pre-screening of a drug-like compound database with 8 × 106 compounds by using the expanded pesticide-likeness criteria, followed by docking-based screening, obtaining 5 top-ranked compounds with favorable docking conformation into OfHex1. Secondly, molecular docking and molecular dynamics simulations are performed for the five complexes and demonstrate that one main hydrophobic pocket formed by residues Trp424, Trp448 and Trp524, which is significant for stabilization of the ligand–receptor complex, and key residues Asp477 and Trp490, are respectively responsible for forming hydrogen-bonding and π–π stacking interactions with the ligands. Finally, the molecular mechanics Poisson–Boltzmann surface area (MM-PBSA) analysis indicates that van der Waals interactions are the main driving force for the inhibitor binding that agrees with the fact that the binding pocket of OfHex1 is mainly composed of hydrophobic residues. These results suggest that screening the ZINC database can maximize the identification of potential OfHex1 inhibitors and the computational protocol will be valuable for screening potential inhibitors of the binding mode, which is useful for the future rational design of novel, potent OfHex1-specific pesticides

Chitosan for gene delivery and orthopedic tissue engineering applications.

Gene therapy involves the introduction of foreign genetic material into cells in order exert a therapeutic effect. The application of gene therapy to the field of orthopaedic tissue engineering is extremely promising as the controlled release of therapeutic proteins such as bone morphogenetic proteins have been shown to stimulate bone repair. However, there are a number of drawbacks associated with viral and synthetic non-viral gene delivery approaches. One natural polymer which has generated interest as a gene delivery vector is chitosan. Chitosan is biodegradable, biocompatible and non-toxic. Much of the appeal of chitosan is due to the presence of primary amine groups in its repeating units which become protonated in acidic conditions. This property makes it a promising candidate for non-viral gene delivery. Chitosan-based vectors have been shown to transfect a number of cell types including human embryonic kidney cells (HEK293) and human cervical cancer cells (HeLa). Aside from its use in gene delivery, chitosan possesses a range of properties that show promise in tissue engineering applications; it is biodegradable, biocompatible, has anti-bacterial activity, and, its cationic nature allows for electrostatic interaction with glycosaminoglycans and other proteoglycans. It can be used to make nano- and microparticles, sponges, gels, membranes and porous scaffolds. Chitosan has also been shown to enhance mineral deposition during osteogenic differentiation of MSCs in vitro. The purpose of this review is to critically discuss the use of chitosan as a gene delivery vector with emphasis on its application in orthopedic tissue engineering

Multifunctional biomaterials from the sea: Assessing the effects of chitosan incorporation into collagen scaffolds on mechanical and biological functionality

Natural biomaterials such as collagen show promise in tissue engineering applications due to their inherent bioactivity. The main limitation of collagen is its low mechanical strength and somewhat unpredictable and rapid degradation rate; however, combining collagen with another material, such as chitosan, can reinforce the scaffold mechanically and may improve the rate of degradation. Additionally, the high cost and the risk of prion transmission associated with mammal-derived collagen has prompted research into alternative sources such as marine-origin collagen. In this context, the overall goal of this study was to determine if the incorporation of chitosan into collagen scaffolds could improve the mechanical and biological properties of the scaffold. In addition the study assessed if collagen, derived from salmon skin (marine), can provide an alternative to collagen derived from bovine tendon (mammal) for tissue engineering applications. Scaffold architecture and mechanical properties were assessed as well as their ability to support mesenchymal stem cell growth and differentiation. Overall, the addition of chitosan to bovine and salmon skin-derived collagen scaffolds improved the mechanical properties, increasing the compressive strength, swelling ratio and prolonged the degradation rate. Mesenchymal stem cell (MSC) attachment and proliferation was most improved on the bovine-derived collagen scaffold containing a 75:25 ratio of collagen:chitosan, and when MSC osteogenic and chondrogenic potential on the scaffold was assessed, a significant increase in calcium production (p < 0.001) and sulfated glycosaminoglycan (sGAG) production (p < 0.001) was observed respectively. Regardless of chitosan content, the bovine-derived collagen scaffolds out-performed the salmon skin-derived collagen scaffolds, displaying a larger pore size and higher percentage porosity, more regular architecture, higher compressive modulus, a greater capacity for water uptake and allowed for more MSC proliferation and differentiation. This versatile scaffold incorporating the marine biomaterial chitosan show great potential as appropriate platforms for promoting orthopaedic tissue repair while the use of salmon skin-derived collagen may be more suitable in the repair of soft tissues such as skin.This work was funded by Science Foundation Ireland (SFI) through the Research Frontiers Programme (Grant No. 11/RFP/ENM/3063) and by the European Regional Development Fund (ERDF) through INTERREG 2007-2013 Program (POCTEP project 0687_NOVOMAR_1_P). Bovine collagen materials were provided by Integra Life Sciences, Inc. through a Material Transfer Agreement. Salmon skins were kindly offered by Pingo Doce, Braga (Portugal)

Predicted Relative Metabolomic Turnover (PRMT): determining metabolic turnover from a coastal marine metagenomic dataset

We present an approach in which the semantics of an XML language is defined by means of a transformation from an XML document model (an XML schema) to an application specific model. The application specific model implements the intended behavior of documents written in the language. A transformation is specified in a model transformation language used in the Model Driven Architecture (MDA) approach for software development. Our approach provides a better separation of three concerns found in XML applications: syntax, syntax processing logic and intended meaning of the syntax. It frees the developer of low-level syntactical details and improves the adaptability and reusability of XML applications. Declarative transformation rules and the explicit application model provide a finer control over the application parts affected by adaptations. Transformation rules and the application model for an XML language may be composed with the corresponding rules and application models defined for other XML languages. In that way we achieve reuse and composition of XML applications

A cognitive prosthesis for complex decision-making

While simple heuristics can be ecologically rational and effective in naturalistic decision making contexts, complex situations require analytical decision making strategies, hypothesis-testing and learning. Sub-optimal decision strategies – using simplified as opposed to analytic decision rules – have been reported in domains such as healthcare, military operational planning, and government policy making. We investigate the potential of a computational toolkit called “IMAGE” to improve decision-making by developing structural knowledge and increasing understanding of complex situations. IMAGE is tested within the context of a complex military convoy management task through (a) interactive simulations, and (b) visualization and knowledge representation capabilities. We assess the usefulness of two versions of IMAGE (desktop and immersive) compared to a baseline. Results suggest that the prosthesis helped analysts in making better decisions, but failed to increase their structural knowledge about the situation once the cognitive prosthesis is removed

Research and Application of Marine Microbial Enzymes: Status and Prospects

Over billions of years, the ocean has been regarded as the origin of life on Earth. The ocean includes the largest range of habitats, hosting the most life-forms. Competition amongst microorganisms for space and nutrients in the marine environment is a powerful selective force, which has led to evolution. The evolution prompted the marine microorganisms to generate multifarious enzyme systems to adapt to the complicated marine environments. Therefore, marine microbial enzymes can offer novel biocatalysts with extraordinary properties. This review deals with the research and development work investigating the occurrence and bioprocessing of marine microbial enzymes