L'autophagie est importante pour le recyclage et la mobilisation des éléments nutritifs dans les plantes. Plusieurs lignées sur-exprimant les gènes AtATG8a-i d’Arabidopsis ont été sélectionnées afin de déterminer l'effet de l'augmentation de l'activité autophagique sur l'efficacité de la remobilisation de l'azote. Les lignées sur-expresseur ont présenté une meilleure remobilisation de l'azote des feuilles de la rosette jusqu'aux graines qque le contrôle, mais uniquement dans des conditions de culture en nitrate pléthorique. Les lignées sur-exprimant ATG8a et ATG8g ont été les plus performantes. Une vaste collection de mutants atg, comprenant les mutants atg8a-i, a ensuite été utilisée pour mesurer la remobilisation de l’azote des rosettes, aux tiges et aux semences, afin de déterminer quels gènes ATG sont essentiels pour la remobilisation. Une attention particulière a été accordée à la famille de gènes ATG8a-i afin de déterminer si un membre de la famille ATG8 pourrait être plus spécifiquement dédié au recyclage de l'azote lors de la sénescence des feuilles pour la remobilisation. Bien que les divers mutants atg8 n’aient pas présenté de différence majeure par rapport au sauvage, l'un d'entre eux a montré un léger phénotype de sénescence précoce, suggérant que cette isoforme pourrait être plus spécialisée dans la remobilisation de l'azote. Afin d'améliorer l'activité de l'autophagie chez l'orge, nous avons surexprimé HvATG5 chez l'orge et testé la sensibilité des sur-expresseurs à plusieurs conditions de stress. Nous avons constaté que les sur-expresseurs de HvATG5 étaient plus tolérants à une faible alimentation en nitrate, à une faible teneur en soufre, et surtout moins sensibles aux effets de l'obscurité prolongée. Afin d'estimer les rôles respectifs des protéases induites par la sénescence et de l'autophagie, plusieurs mutants de protéase (sag12, rd21A, cathB3) ont été croisés avec des mutants d'autophagie (atg5, atg7. Leur contribution à la remobilisation de l'azote a été mesurée par marquage 15N. / Autophagy is important for nutrient recycling and mobilization in plants. Several Arabidopsis AtATG8a-i overexpressing lines were selected in order to determine the effect of increasing autophagy on nitrogen remobilization efficiency. The overexpressing lines remobilized more nitrogen from the rosette leaves to the seeds but only when cultivated under high nitrate conditions. The lines overexpressing ATG8a and ATG8g were the most performant. A large collection of atg mutants including the atg8a-i mutants was then used to monitor N-remobilization from the rosettes to the stems and seeds in order to determine which ATG genes are essential for N remobilization. A special focus was dedicated to the ATG8a-i gene family in order to determine whether a member of the ATG8 family could be more specifically dedicated to N-recycling during leaf senescence for remobilization. Although the various atg8 mutants were not different from wild-type, one of them presented slight early senescence phenotype, suggesting this isoform could be more specialized in N remobilization. In order to enhance autophagy activity in barley, we overexpressed HvATG5 in barley and tested sensitivity of over-expressors to several stress conditions. We found that barley HvATG5 over-expressors were more tolerant to low nitrate supply, to low sulfur, and especially less sensitive to dark-stress effects. In order to estimate the respective roles of autophagy and senescence induced proteases, several protease mutants (sag12, rd21A, cathB3) were crossed with autophagy mutants (atg5, atg7) in order to monitor their respective contributions to nitrogen remobilization.

<p>The Norwegian system for depositing and recycling of PET bottles (Resirk/PET system)started in May 2000, and is based on Norsk Resirk's mission of improving cost- and environmental efficiency of this system. Has this been achieved? What can explain the changes that occurred in the system during recent years? I have found that the eco-efficiency of the Resirk/PET system increased considerably every year between 2000 and 2003. The net greenhouse gas (GHG emission was improved from -562 kg CO2e (562 kg CO2 equivalents avoided generated) for waste management of one tonne consumed bottles in 2000 to -1442 kg CO2e per tonne in 2003, while the net cost was reduced from 4062 €/tonne in 2000 to 2683 €/tonne in 2003. This eco-efficiency improvement was very much driven by the increased volume and return rate of PET bottles during this period. The environmental performance of the Resirk/PET system was high compared to other waste management systems for PET bottles, while the economical performance was considerably lower. The interactive development of the bottled non-carbonated mineral water Imsdal contributed significantly to the increase of the Resirk/PET system’s volume and return rate and hence the system’s improved eco-efficiency. A white spirit sabotage on Imsdal in August 2002 contributed to the development of Imsdal as well as the Resirk/PET system’s change of the design and material specification for participating PET bottles. By combining the quantitative eco efficiency framework with the qualitative framework of interactive resourced development, information about how much eco-efficiency of a defined system has changed, as well as an understanding of reasons for changes within the system, has been acquired. Such a combination should be possible to apply for analysis of other systems as well, and may be a valuable contribution to the field of industrial ecology since the methods complement each other in a fruitful way. The eco-efficiency of the Resirk/PET system can be improved further by:</p><p>- Regarding used PET bottles as a resource to be applied for production</p><p>- Reducing packaging tax for PET bottles</p><p>- Increasing the bottle deposit</p><p>- Keeping the PET specification updated</p><p>- Improving collection efficiency</p><p>- Improving cost efficiency of marketing and information</p><p>- Increasing compaction and filling degree of reverse vending machines</p><p>- Considering automatic sorting</p><p>- Keeping focus on producing high quality PET flakes.</p><p>In addition to having showed that the approaches of eco-efficiency and interactive resource development can be combined, this thesis may have implications on how ecoefficiency can be quantified in waste management systems, and how the concepts of adaptation and friction in resource structures are dealt with.</p>

The Norwegian system for depositing and recycling of PET bottles (Resirk/PET system)started in May 2000, and is based on Norsk Resirk's mission of improving cost- and environmental efficiency of this system. Has this been achieved? What can explain the changes that occurred in the system during recent years? I have found that the eco-efficiency of the Resirk/PET system increased considerably every year between 2000 and 2003. The net greenhouse gas (GHG emission was improved from -562 kg CO2e (562 kg CO2 equivalents avoided generated) for waste management of one tonne consumed bottles in 2000 to -1442 kg CO2e per tonne in 2003, while the net cost was reduced from 4062 €/tonne in 2000 to 2683 €/tonne in 2003. This eco-efficiency improvement was very much driven by the increased volume and return rate of PET bottles during this period. The environmental performance of the Resirk/PET system was high compared to other waste management systems for PET bottles, while the economical performance was considerably lower. The interactive development of the bottled non-carbonated mineral water Imsdal contributed significantly to the increase of the Resirk/PET system’s volume and return rate and hence the system’s improved eco-efficiency. A white spirit sabotage on Imsdal in August 2002 contributed to the development of Imsdal as well as the Resirk/PET system’s change of the design and material specification for participating PET bottles. By combining the quantitative eco efficiency framework with the qualitative framework of interactive resourced development, information about how much eco-efficiency of a defined system has changed, as well as an understanding of reasons for changes within the system, has been acquired. Such a combination should be possible to apply for analysis of other systems as well, and may be a valuable contribution to the field of industrial ecology since the methods complement each other in a fruitful way. The eco-efficiency of the Resirk/PET system can be improved further by: - Regarding used PET bottles as a resource to be applied for production - Reducing packaging tax for PET bottles - Increasing the bottle deposit - Keeping the PET specification updated - Improving collection efficiency - Improving cost efficiency of marketing and information - Increasing compaction and filling degree of reverse vending machines - Considering automatic sorting - Keeping focus on producing high quality PET flakes. In addition to having showed that the approaches of eco-efficiency and interactive resource development can be combined, this thesis may have implications on how ecoefficiency can be quantified in waste management systems, and how the concepts of adaptation and friction in resource structures are dealt with.