Riassunto:
We are witnessing an increased awareness of the earth's environment. Examples are easily seen in the rise of 'Green Parties' across Europe, North America, Australasia, and lately Eastern Europe. The public outcry following industrial mishaps in Alaska, Chernobyl, Basel, and Bhopal, as well as the renewed legislative activity, such as the Clean Air Act in the USA and the European Community directive to member nation concerning the control of release of genetically engineered organisms are further examples of the general interest in the biosphere. The 'Ozone hole', 'Greenhouse gases', and 'Genetically engineered Microorganisms' have gained public profiles, and are discussed widely in newspapers, magazines and the electronic media. A recent educational survey of nations, belonging to the Organisation for Economic Co-operation and Development (OECD) showed that school children are more literate with ecological terms (as listed above) than with 'pure' scientific terms, like 'phloem', 'mitosis', 'proton', or 'Jurasic period'. Perhaps the increase in awareness is cyclical, being fed by non-scientific, sociological and economic advances. The late 1960s/early 1970s saw a major increase in environmental consciousness. Anti-pollution groups were founded, healthfood shops and naturopathy became acceptable as did recycling, the use of lead-free gasoline, and the reduced usage of environmental toxins, like DDT and PCB. For example, Monsanto Chemical Company instigated a self-imposed halt to the manufacture of PCB in the mid-seventies. Chemical companies started to look at biodegradable herbicides, slow release fertilizers, and specifically targeted pesticides.
Contenuti:
Overview Section.- Recent studies on the biochemistry and chemistry of nitrogenases.- Nodulation genetics: the plant-bacterial interface.- Physiological, metabolic and developmental implications of O2 regulation in legume nodules.- Regulation of nitrogen fixation and assimilation genes in the free-living versus symbiotic state.- Evolution, structure and function of nitrogen-fixing root nodules: confessions of ignorance.- Nitrogen cycling and human intervention.- H2 cycling in N2 fixation: past, present and future outlook.- Section A: Nitrogenase Biochemistry and Chemical Models.- Analysis of Azotobacter vinelandii strains containing defined deletions in nif genes required for FeMo-co biosynthesis.- In vitro synthesis of the iron-molybdenum cofactor and its analogs: requirement of a non-nif gene product for the synthesis, and altered properties of dinitrogenase.- Identification of FeMoco domains within the nitrogenase MoFe protein.- Kinetics and mechanisms of ATP hydrolysis, electron transfers and proton release by Klebsiella pneumoniae nitrogenase.- Crystal structure of the nitrogenase iron protein from Azotobacter vinelandii.- Structure of the nitrogenase MoFe protein: spatial distribution of the intrinsic metal atoms determined by x-ray anomalous scattering.- Vanadium nitrogenase of Azotobacter.- Possible structural analogs for the Fe/M/S sites in the nitrogenases. The[Fe6S6(L)6(M(CO)3)2]n- clusters and the [(MFe3S4)2(?2-S)(?2-L)]n- singly- and doubly-bridged double cubanes.- Workshop summary: How is the MoFe protein organized to fix nitrogen?.- Poster Summaries.- Section B: Plant-Microbe Interactions.- Rhizobium meliloti nodulation genes specify the production of an alfalfa-specific sulfated lipo-oligosaccharide signal.- Surface interactions between rhizobia and legume root hairs.- Isolation, characterization, and structural elucidation of a “nod signal” excreted by Rhizobium trifolii ANU843 which induces root hair branching and nodule-like primordia in axenic white clover seedlings.- Recent studies on the Rhizobium-legume symbiosis.- The Rhizobium leguminosarum bv. viciae NodO protein compensates for the exported signal made by the host-specific nodulation genes.- Rhizobium meliloti nodulation genes and their regulation.- Regulatory steps in nodulation by Rhizobium leguminosarum bv. viciae.- Nutrient exchange across the peribacteroid membrane of isolated symbiosomes.- Immunological dissection of the plant-microbe interface in pea nodules.- Endosymbiosis of Rhizobium: Internalization of the “extracellular compartment” and metabolites exchange.- Compilation of the nod, fix, and nif genes of Rhizobia and information concerning their function.- Poster Summaries.- Section C: Limiting Factors in Nitrogen Fixation.- Limiting factors in symbiotic nitrogen fixation: structure and dynamics of the Rhizobium genome.- Oxygen diffusion in the legume root nodule.- A genetic approach to analyze the critical role of oxygen in bacteroid metabolism.- Molecular analysis of terminal oxidases in electron transport pathways of Bradyrhizobium japonicum and Azotobacter vinelandii.- Metabolism of C4-dicarboxylates and amino acids in soybean nodule bacteroids, and their role in energy supply to nitrogenase.- Measurement of N2 fixation by 15N natural abundance in the management of legume crops: roles and precautions.- Genetic analysis of sym genes and other nodule-related genes in Pisum sativum.- Host legume control of nodulation by flavonoids.- Poster Summaries.- Section D: Nitrogen Fixation and the Environment.- Ecological aspects of nitrogen fixation.- The ecology of indigenous populations of Rhizobium leguminosarum bvs. trifolii and viceae.- Molecular analysis of the denitrification system of pseudomonads.- Production of nitrite and N2O by the ammonia-oxidizing nitrifiers.- Planned release of genetically modified organisms: scientific and regulatory issues.- Field release of genetically-engineered Rhizobium meliloti and Bradyrhizobium japonicum strains.- Assessment of genetically engineered microorganisms under the Toxic Substances Control Act: considerations prior to small-scale release.- Poster Summaries.- Section E: Bacterial Systems.- Regulation of the C4-dicarboxylate transport in free-living and symbiotic Rhizobium meliloti.- Transcriptional activation of nitrogen fixation genes in Klebsiella pneumonia.- Mechanism of transcription from nif promoters: involvement of IHF.- Organization and regulation of nitrogen fixation genes in Rhodobacter capsulatus.- The genetics and biochemistry of the reversible ADP-ribosylation systems of Rhodospirillum rubrum and Azospirillum lipoferum.- Nitrogen fixation genes of Clostridium pasteurianum.- Azospirillum associations.- Nitrogen fixation in filamentous cyanobacteria.- Hydrogen metabolism and the alternative nitrogenase in the cyanbacterium Anabaena variabilis.- Poster Summaries.- Section F: Nitrogen Fixation in Agriculture and Industry.- to nitrogen fixation in agriculture and industry: contribution of BNF to sustainability of agriculture.- Improvement of inoculant efficiency by strain improvement and formulation manipulations.- Agronomic and economic benefits of nitrogen contributed by legumes in live-mulch and alley cropping systems.- Stem-nodule symbiosis and its unusual properties.- Workshop summary: What are the applications of our research to ecology and agriculture worldwide?.- Poster Summaries.- Section G: Plant Function.- Protein synthesis and protein phosphorylation in Bradyrhizobium japonicum bacteroids.- Some nodulin and Nod proteins show similarity to specific animal proteins.- Alfalfa root nodule aspartate aminotransferase (AAT): Biochemical importance and genetic control.- Regulation of host gene expression during nodule development in soybeans.- Nodulins and nodule development.- Regulation of expression of the GLN-? gene of Phaseolus vulgaris L.- The glutamine synthetases of Rhizobium leguminosarum and their regulatory genes.- Workshop summary: How can we couple the genetics and physiology of nodule function?.- Poster Summaries.- Section H: Nitrogen Fixation and Evolution.- Evolving a Rhizobium for non-legume nodulation.- Hypotheses for the evolution of actinorhizal symbioses.- Genetics of alternative nitrogen fixation systems in Azotobacter vinelandii.- Nitrogen fixation in Methanosarcina barkeri strain 227.- The first photosynthetic N2-fixing Rhizobium: Characteristics.- Nodulation of non-legumes by rhizobia.- Poster Summaries.- Section I: Summing up the Congress.- Congress summary: the molecular perspective.- Congress summary: the organismal perspective.- Computer networking and biological nitrogen fixation.- Author Index.
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