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LIGANDS OF TECHNETIUM AND TRANSFER

Objective

THE RESEARCH PROPOSAL CAN BE SUMMARIZED AS FOLLOWS:
- A STUDY OF THE BIO-ORGANIC LIGANDS OF CYTOSOL TC;
- A STUDY OF THE METABOLITES LINKING TC AND THE ACTINIDES;
- AFFINITY OF TC ACCORDING TO THE ORGANIC LIGAND (FIXATION SITES)
The evolution of different bioorganic ligands of technetium at the metabolic level and their elimination at the molecular level have been studied. The passage of technetium throughbiological systems has been examined at the level of biologial surfaces (membranes), organelles of detoxification (Lysosomes) and at the soluble level (proteins).
THE TECHNETIUM DISCHARGED INTO THE ENVIRONMENT DERIVES CHIEFLY FROM THE USE OF NUCLEAR ENERGY FOR MILITARY AND CIVIL PURPOSES. DURING THE FUEL CYCLE, THIS ELEMENT IS RELEASED MAINLY AT THE ENRICHMENT AND REPROCESSING STAGES. WHAT IS IMPORTANT TO KNOW IS THAT, IN THE SOIL, TC IS PRESENT IN THE OXYDIZED ANIONIC FORM TCO4. IN THE ABSENCE OF POWERFUL REDUCING AGENTS, THIS CHEMICAL FORM IS VERY MOBILE.
OUR EARLIER STUDIES REVEALED THE EXISTENCE OF TC COMPLEXES WITH BIO-ORGANIC MACROMOLECULES OF HIGH MOLECULAR WEIGHT (150 000) AND LOW MW (LESS THAN 10 000), THE AFFINITY OF THE METAL BEING GREATER IN THE SECOND CASE. AN ANALYSIS OF THESE COMPLEXES WAS PERFORMED AND A PRECISE STUDY OF THEIR STRUCTURE WILL ENABLE US TO IDENTIFY THE LINKAGE SITES AND THE SPATIAL STRUCTURE. SINCE PRINZ AND WESER (1975) PURIFIED A CUPRIC COMPLEX OF MW 9500 IN YEASTS, THE WAY HAS BEEN OPEN TO STUDIES ON THE METAL UPTAKE OF MICRO-ORGANISMS, AND ON THE METABOLISM, TRANSPORT AND ELIMINATION OF METAL. IT IS EXTREMELY LIKELY THAT THE TRANSIT OF TC THROUGH BIO-ORGANIC SYSTEMS GIVES RISE TO NEW COMPLEXES AFFECTING THE PHYSICAL AND CHEMICAL FORM OF TC AND ALSO ITS BIOAVAILABILITY.
THE LIGAND EXCHANGE PHENOMENA WILL DEPEND ON THE STRUCTURE OF THE ASSOCIATED METABOLITE AND ON ITS PHYSICAL AND CHEMICAL CHARACTERISTICS.
THE WORK BEGUN IN COOPERATION WITH MARINE RADIOECOLOGISTS HAS ALREADY BEEN COMPLETED. THE LABORATORIES USING SPIKED ANIMALS AS MARKERS WISH TO ACQUIRE MORE DETAILED KNOWLEDGE OF THE TRANSFER MECHANISMS AT ORGANIC AND SUB-CELLULAR LEVEL AND IDENTIFY THE RETENTION AND ELIMINATION PROCESSES (LINKED PROTEINS OF HIGH AND LOW MOLECULAR WEIGHT, METALLOTHIONEINS, ETC.).
THE PHENOMENA OF COMPETITION BETWEEN ELEMENTS IN THE SOIL QUITE NATURALLY BRING US TO THE PROBLEMS ASSOCIATED WITH LIGAND EXCHANGE OF RELEVANCE TO THIS PROGRAM (ACTION OF LAND MICRO-ORGANISMS). IN ALL CASES, THE BIOLOGICAL PRODUCTS PARTICIPATING IN THE FORMATION OF BIOLOGICAL SURFACES (MEMBRANES) DERIVED FROM VARIOUS ORGANISMS (MICRO-ORGANISMS AND EUCARYOTES) FROM THESE LABORATORIES WILL BE EXAMINED. IN THIS CONTEXT, THE AIM IS TO DETERMINE THE ROLE OF ACTIVE AND PASSIVE UPTAKE PHENOMENA IN RELATION TO THE RETENTION AND TRANSFER OF THE ELEMENTS UNDER STUDY.
ALL THE BIOLOGICAL UPTAKE, RETENTION, MOLECULAR-LEVEL STORAGE AND DETOXIFICATION MECHANISMS CAN BE EVALUATED. THESE PARAMETERS WILL BE PROVIDED TO A SPECIALIZED LABORATORY SO THAT MODELS CAN BE FORMULATED.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Université de Nantes
Address
2 Rue De La Houssinière
44072 Nantes
France