A functional analysis of the pyrimidine catabolic pathway in Arabidopsis

Reductive catabolism of pyrimidine nucleotides occurs via a three-step pathway in which uracil is degraded to β-alanine, CO2 and NH3 through sequential activities of dihydropyrimidine dehydrogenase (EC 1.3.1.2, PYD1), dihydropyrimidinase (EC 3.5.2.2, PYD2) and β-ureidopropionase (EC 3.5.1.6, PYD3).A proposed function of this pathway, in addition to the maintenance of pyrimidine homeostasis, is the recycling of pyrimidine nitrogen to general nitrogen metabolism. PYD expression and catabolism of [2-14C]-uracil are markedly elevated in response to nitrogen limitation in plants, which can utilize uracil as a nitrogen source.PYD1, PYD2 and PYD3 knockout mutants were used for functional analysis of this pathway in Arabidopsis. pyd mutants exhibited no obvious phenotype under optimal growing conditions. pyd2 and pyd3 mutants were unable to catabolize [2-14C]-uracil or to grow on uracil as the sole nitrogen source. By contrast, catabolism of uracil was reduced by only 40% in pyd1 mutants, and pyd1 seedlings grew nearly as well as wild-type seedlings with a uracil nitrogen source. These results confirm PYD1 function and suggest the possible existence of another, as yet unknown, activity for uracil degradation to dihydrouracil in this plant.The localization of PYD-green fluorescent protein fusions in the plastid (PYD1), secretory system (PYD2) and cytosol (PYD3) suggests potentially complex metabolic regulation

Engineering an endocrine Neo-Pancreas by repopulation of a decellularized rat pancreas with islets of Langerhans

Decellularization of pancreata and repopulation of these non-immunogenic matrices with islets and endothelial cells could provide transplantable, endocrine Neo- Pancreata. In this study, rat pancreata were perfusion decellularized and repopulated with intact islets, comparing three perfusion routes (Artery, Portal Vein, Pancreatic Duct). Decellularization effectively removed all cellular components but conserved the pancreas specific extracellular matrix. Digital subtraction angiography of the matrices showed a conserved integrity of the decellularized vascular system but a contrast emersion into the parenchyma via the decellularized pancreatic duct. Islets infused via the pancreatic duct leaked from the ductular system into the peri- ductular decellularized space despite their magnitude. TUNEL staining and Glucose stimulated insulin secretion revealed that islets were viable and functional after the process. We present the first available protocol for perfusion decellularization of rat pancreata via three different perfusion routes. Furthermore, we provide first proof-of-concept for the repopulation of the decellularized rat pancreata with functional islets of Langerhans. The presented technique can serve as a bioengineering platform to generate implantable and functional endocrine Neo-Pancreata

City oder Suburb - Wohnoptionen für Familien im gesellschaftlichen Wandel : untersucht in Düsseldorf-Innenstadt und Neuss-Allerheiligen

Social and economic changes provoke changes in housing needs, aspirations and options. Families with children, who constitute the germ cells at the nucleus of society, are owed particular attention in this respect. Because parents are bound by their caring duties during the children's minority, they are subject to a number of restraints and exigencies as regards their choice of living environment. These kinds of households, therefore, have many special characteristics and needs which may be strongly affected by changes in their local environment which in turn affect their everyday life. In Germany, the shift from Fordism, with its prescribed role models, family structure and living patterns, into Late Modern Society, in which these patterns are seen to have evolved and changed, has been seen to have impacted on families' housing options. Suburban lifestyle has been regarded as the dominant pattern for decades; now urban environments are being discussed as suitable options for families as they are seen to provide more timely opportunities for enmeshing child rearing and career. Although in fact there is a certain awareness of families in inner city areas, official statistics continue to indicate that families are still moving to the outskirts. The thesis postulated for this study implies that the mobility of families is not in fact dictated by dominant pattern but rather by their individual lifestyle choices, as well as their typical needs and the quality of the settlement structures (open to them). Part A of the thesis defines “family” more precisely and explains the different dimensions of family life (parameters?) including individual needs of the individual members, effects of social change, and typical strategies for dealing with constraints. They can be separated into qualitative, (e.g. traffic abatement) quantitative, (e.g. number of rooms), and time management aspects, (e.g. saving time thanks to structures for improving flexibility, for externalizing and rationalizing). The results lead to a kind of catalogue of requirements. This catalogue serves for a matrix that allows comparison between different types of settlement structure and examination of their fitness for families. Part B presents the explorative section of the research. Duesseldorf and Neuss-Allerheiligen were chosen as examples of urban and suburban structures. In both places, families were selected for interviews from Late Modern Society - social types with both parents working. They were asked about their motivation in choosing the areas they lived in at present, about their housing situation and about their daily routines and on-site time management. Their answers have been described, systematized in theme complexes and analysed. Part C contains the conclusions of the research. One significant result is the evident increase of options, because urban as well as suburban settlement structures evidently provide opportunities for good living conditions. Families are interpreting spaces in new ways, modifying their functions and making them fit. Thus the importance of pattern is giving way to the superimposition of individual lifestyles. An ex-ample of the strengths of the suburban choice is the “home advantage” As many of the parents in the study grew up in suburban settings themselves, they are able to draw on a good supporting network, (friends, grandparents and their neighbors). Some even venture into establishing “multi-generational” households in a developing area. A strength of the urban ambiance is a certain “flatrate-city-character,” which allows parents the flexibility to open larger windows of time in their daily schedules allowing for more opportunities for their multiple activities. Furthermore, cities offer specialized locations for like-minded persons to share, where everyday life can be extended into public space and social networks developed in this way. The results of this research conclude with recommendations for action in the field of town planning, because one of the most important challenges for those responsible for communal planning is to provide attractive and suitable living spaces - especially for families