Policy processes and collective action in water reforms: the cases of Nicaragua and Suriname

Las reformas de agua en países en desarrollo suelen llevarse a cabo junto con cambios institucionales más profundos o, incluso, acompañadas de cambios constitucionales o de régimen político. Por lo tanto, los marcos institucionales adaptados a países gobernados sujetos al estado de derecho pueden no ser apropiados para contextos gobernados fundamentalmente, al menos en sus inicios, por instituciones informales o poco maduras. Esta tesis toma las reformas de agua como punto de partida y pretende contribuir a la literatura mediante una serie de análisis empíricos tanto del ámbito general como del plano individual o sujeto personal de la política del agua. En el ámbito general, el foco se pone en los factores que explican el fallo de la acción colectiva en dos contextos diferentes: 1) en la implementación de la nueva Ley de Aguas de Nicaragua y 2) en el mantenimiento y revitalización de las instituciones de riego en Surinam. En el plano del individuo, la investigación se centra en las decisiones de los usuarios de los recursos y analiza el papel crítico de las variables sociales para la gestión de los recursos comunes. Para ello, el método de investigación utilizado es mixto, combinando el análisis de entrevistas, encuestas y experimentos. En el ámbito general, los resultados muestran que las principales barreras para la implementación de la nueva Ley de Aguas de Nicaragua podrían tener su reflejo en el lenguaje de la Ley y, por tanto, en la forma en la que se definen y configuran las instituciones incluidas en dicha Ley. Así, la investigación demuestra que la implementación de políticas no puede ser estudiada o entendida sin tener en cuenta tanto el diseño de la propia política como el marco socio-ecológico en el que se enmarca. El contexto específico de Nicaragua remarca la importancia de considerar tanto las instituciones formales como informales en los procesos de transición política. A pesar de que las reformas de agua requieren plazos largos para su implementación, el hecho de que exista una diferencia entre las reglas tal cual se definen formalmente y las reglas que operan en la realidad merece una mayor consideración en el diseño de políticas basadas fundamentalmente en instituciones formales. En el ámbito de la conducta individual, el análisis de la acción colectiva ofrece una serie de observaciones empíricas interesantes. En el caso de Nicaragua, los resultados indican que la intensidad de las relaciones sociales, el tipo de agentes dispuestos a proporcionar apoyo social y el nivel de confianza en la comunidad son factores que explican de manera significativa la participación en la comunidad. Sin embargo, el hecho de que la gestión colectiva de riego se produzca, en la mayoría de casos, en torno a lazos familiares sugiere que las variables de capital social críticas se definen en gran medida en la esfera familiar, siendo difícil que se extiendan fuera de estos nexos. El análisis experimental de los resultados de un juego de uso de recurso común y contribución al bien público muestra que las preferencias pro-sociales de los individuos y la heterogeneidad del grupo en términos de composición por sexo son factores que explican significativamente los resultados y las decisiones de apropiación a lo largo del juego. En términos del diseño de las políticas, es fundamental tener en cuenta las dinámicas de participación y uso de los recursos comunes de manera que los niveles de cooperación puedan mantenerse en el largo plazo, lo cual, como se observa en el caso de Surinam, no es siempre posible. Finalmente, el caso de Surinam es un ejemplo ilustrativo de los procesos de acción colectiva en economías en transición. El análisis del fallo de la acción colectiva en Surinam muestra que los procesos políticos vinculados al período colonial y de independencia explican en gran medida la falta de claridad en las reglas operacionales y colectivas que gobiernan la gestión de los sistemas de riego y drenaje. Los resultados empíricos sugieren que a pesar de que la acción colectiva para la provisión de los servicios de riego y drenaje estaba bien establecida bajo el régimen colonial, la auto-organización no prosperó en un contexto dependiente del apoyo externo y regido fundamentalmente por reglas diseñadas al nivel competencial del gobierno central. El sistema socio-ecológico que se desarrolló durante la transición post-colonial favoreció, así, la emergencia de comportamientos oportunistas, y posteriormente la inoperancia de los Water Boards (WBs) creados en la época colonial. En este sentido, cualquier intento por revitalizar los WBs y fomentar el desarrollo de la auto-organización de los usuarios necesitará abordar los problemas relacionados con los patrones demográficos, incluyendo la distribución de la tierra, el diseño de instituciones y la falta de confianza en el gobierno, además de las inversiones típicas en infraestructura y sistemas de información hidrológicos. El liderazgo del gobierno, aportando empuje de arriba-abajo, es, además, otro elemento imprescindible en Surinam. ABSTRACT Water reforms in developing countries take place along deeper institutional and even constitutional. Therefore, institutional frameworks that might result in positive outcomes in countries governed by the rule of law might not fit in contexts governed mainly by informal or immature institutions. This thesis takes water reforms as the starting point and aims to contribute to the literature by presenting several conceptual and empirical analyses at both general and individual levels. At the general national level, the focus is on the factors explaining failure of collective action in two different settings: 1) in the implementation of the new Nicaraguan Water Law and 2) in sustaining and revitalizing irrigation institutions in Suriname. At the individual level, the research focuses on the actions of resource users and analyzes the critical role of social variables for common pool resources management. For this purpose, the research presented in this thesis makes use of a mixed-method approach, combining interviews, surveys and experimental methods. Overall, the results show that major barriers for the implementation of the new Nicaraguan Water Law have its reflection on the language of the Law and, therefore, on the way institutions are defined and configured. In this sense, our study shows that implementation cannot fruitfully be studied and understood without taking into account both the policy design and the social-ecological context in which it is framed. The specific setting of Nicaragua highlights the relevance of considering both formal and informal institutions when promoting policy transitions. Despite the unquestionable fact that water reforms implementation needs long periods of time, there is still a gap between the rules on paper and the rules on the ground that deserves further attention when proposing policy changes on the basis of formal institutions. At the level of the individual agent, the analysis of collective action provides a number of interesting empirical insights. In the case of Nicaragua, I found that the intensity of social networks, the type of agents willing to provide social support and the level of trust in the community are all significant factors in explaining collective action at community level. However, the fact that most collective irrigation relies on family ties suggests that critical social capital variables might be defined within the family sphere and making it difficult to go beyond it. Experimental research combining a common pool resource and a public good game in Nicaragua shows that individuals’ pro-social traits and group heterogeneity in terms of sex composition are significant variables in explaining efficiency outcomes and effort decisions along the game. Thus, with regard to policy design, it is fundamental to consider carefully the dynamics of agents' participation and use of common pool resources, for sustaining cooperation in the long term, which, as seen in the case and Surinam, is not always possible. The case of Suriname provides a rich setting for the analysis of collective action in transition economies. The analysis of decay of collective irrigation in Suriname shows that the lack of clear operational and collective choice rules appear to be rooted in deeper political processes that date back to the colonial period. The empirical findings suggest that despite collective action for the provision of irrigation and drainage services was well established during the colonial period, self-organization did not flourish in a context governed by colonial state-crafted rules and mostly dependent on external support. The social-ecological system developed during the post-colonial transition process favored the emergence of opportunistic behavior. In this respect, any attempt to revitalize WBs and support self-organization will need to tackle the problems derived from demographic patterns, including land allocation, institutions design and government distrust, in addition to the typical investments in both physical infrastructure and hydrological information systems. The leadership role of the government, acting as a top-down trigger, is another essential element in Suriname.

Accessibility instruments for planning practice: bridging the gap between academic research and decision-making.

One of the core objectives of urban planning practice is to provide spatial equity in terms of opportunities and use of public space and facilities. Accessibility is the element that serves this purpose as a concept linking the reciprocal relationship between transport and land use, thus shaping individual potential mobility to reach the desired destinations. Accessibility concepts are increasingly acknowledged as fundamental to understand the functioning of cities and urban regions. Indeed, by introducing them in planning practice, better solutions can be achieved in terms of spatial equity. The COST Action TU1002 "Accessibility instruments for planning practice" was specifically designed to address the gap between scientific research in measuring and modelling accessibility, and the current use of indicators of accessibility in urban planning practice. This paper shows the full process of introducing an easily understandable measure of accessibility to planning practitioners in Madrid, which is one of the case studies of the above-mentioned COST action. Changes in accessibility after the opening of a new metro line using contour measures were analyzed and then presented to a selection of urban planners and practitioners in Madrid as part of a workshop to evaluate the usefulness of this tool for planning practice. Isochrone maps were confirmed as an effective tool, as their utility can be supplemented by other indicators, and being GIS-based, it can be easily computed (when compared with transport models) and integrated with other datasets.

Capacity Building through education, research and collaboration: AFRICA BUILD, an eHealth Case Study

AFRICA BUILD (AB) is a Coordination Action project under the 7th European Framework Programme having the aim of improving the capacities for health research and education in Africa through Information and Communication Technologies (ICT). This project, started in 2012, has promoted health research, education and evidence-based practice in Africa through the creation of centers of excellence, by using ICT,?know-how?, eLearning and knowledge sharing, through Web-enabled virtual communities.

Participación Directa y Aprendizaje de los Trabajadores en Mejoras Tecnológicas a Empresas Bajo Gestión Colectiva. Aplicación en Industrias Metalúrgicas de Venezuela y Argentina

La industria metalúrgica estatal venezolana ha vivido, desde sus inicios, procesos cíclicos de cambios y ajustes tecnológicos. Estos procesos no han sido objeto de sistematización que asegure el aprendizaje y apropiación del conocimiento. Este hecho, aún hoy, ha obstaculizado los procesos de apropiación y mejora de las tecnologías asociadas al sector. A partir del acompañamiento a iniciativas de participación de grupos de interés surgidos del seno de los trabajadores, se planteó esta investigación que tuvo como propósito la determinación de condiciones y relaciones para su participación directa en los procesos de mejora de las tecnologías existentes y el fortalecimiento del aprendizaje asociado. Se consideraron dos ámbitos Latinoamericanos donde hay manifestación de gestión colectiva y participación: Venezuela y Argentina. En el caso venezolano, el abordaje se realizó bajo la Investigación Acción Participativa (IAP), desarrollando la “investigación próxima”, como estrategia de acompañamiento, mediante “talleres de formación-investigación” y la sistematización de experiencias considerando la perspectiva y necesidades de los actores. En el caso argentino, el abordaje se realizó mediante visitas, entrevistas, reuniones y encuentros. Los talleres realizados en Venezuela, en un contexto de diálogo de saberes, facilitaron el surgimiento de herramientas prácticas para la sistematización de su propia experiencia (“Preguntas generadoras”, “Mi historia con la tecnología”, “Bitácora de aprendizaje”). El intercambio con los pares argentinos ha generado una red que plantea la posibilidad de construcción y nucleación conjunta de saberes y experiencia, tanto para los trabajadores como para los investigadores. Los casos estudiados referidos a las empresas recuperadas por los trabajadores (ERTs) argentinos evidencian un proceso de participación marcada por su autonomía en la gestión de la empresa, dadas las circunstancias que los llevó a asumirla para conservar sus puestos de trabajo. De estos casos emergieron categorías asociadas con elementos de gestión de un proceso técnico–tecnológico, como la participación en la planificación, concepción o diseño de la mejora. La participación en general está asociada al hecho asambleario, vinculado a las prácticas de toma de decisiones autogestionarias como expresión de una alta participación. La Asamblea, como máxima instancia de participación, y el Consejo de Administración son las formas de participación prevalecientes. En cuanto al aprendizaje, los trabajadores de las ERTs argentinas aportaron categorías de gran significación a los procesos de socialización del conocimiento: conocimiento colectivo y cooperación del conocimiento, rescate de los saberes y formación de trabajadores que tomen el relevo. Las categorías surgidas de las ERTs argentinas, los referentes teóricos y el interés de los trabajadores venezolanos fueron la base para la valoración tanto de su grado de participación en las mejoras a procesos tecnológicos emprendidas, como del aprendizaje asociado. Ésta valoración se realizó bajo una aproximación borrosa dado el carácter ambiguo de estas categorías que fueron trabajadas como conjuntos que se relacionan, más que como variables. Se encontró que la participación, se configura como un sub-conjunto del aprendizaje para contribuir a su fortalecimiento. Las condiciones y relaciones para fortalecer la participación en los asuntos tecnológicos surgieron a partir de la sistematización y síntesis de ambas experiencias (Venezuela y Argentina) conjugando una estructura que contempla la formación para la nucleación de colectivos de saberes (proyectos de mejora o innovaciones), las redes por afinidad, la sistematización de su propia experiencia técnica y los enlaces institucionales. Estos resultados dan cuenta de la integración de los intereses de las partes (trabajadores, investigadores, instituciones), mediante las estrategias de encuentro, de sistematización de los propios métodos y de conformación de los “colectivos de saberes”, la red de IAP en la industria (IAP Industrial) considerando la “deriva de la investigación”, bajo discursos práctico–teóricos propios, como posibilidad de posicionamiento de su participación en los asuntos tecnológicos de sus respectivas organizaciones, abriendo una oportunidad de ampliación de la experiencia en otros ámbitos y sectores. ABSTRACT Venezuelan's state owned steel industry has experienced since its earliest years, cycles of change and technological adjustments. These processes have not been systematized to ensure learning and knowledge in those organizations. This fact, even today, has hindered the processes of appropriation and improving the technologies associated with the sector. In order to support initiatives involving metalworker interest groups, this research was aimed at determining conditions and relations for their direct participation in process improvements to existing technologies and strengthening the associated learning. Two Latin American countries, Venezuela and Argentina, were considered on the base of their collective management and participation experiences. The Venezuelan approach was carried out under the Participatory Action Research (PAR) strategy, through the ‘proximal research’ as support strategy, by means of ‘workshops–research’ and systematization of experiences considering the perspective and needs of actors. Workshops were carried out in metallurgical enterprises from steel and aluminum at Guayana, Venezuela and its affiliates in the Central region. Those industries have been promoted collective management. The Argentine approach was carried out through visits, interviews, meetings and gatherings. The workshops held in Venezuela, in a dialogue of knowledge context, facilitated the emergence of tools for the systematization of their own experience (‘generating questions’, ‘My history with technology’, ‘Learning Log’). The relation with Argentine peers has generated a network that creates opportunities of knowledge and experience construction and its nucleation for both, workers and researchers. The cases studied relating to Argentine workers’ recuperated enterprises show a participatory process marked by autonomy in the management of the factory, given the circumstances that led them to take it in order to maintain their jobs. From these cases emerged categories associated with management aspects about technical-technology process, such as participation in planning, design or implementation of the improvement. Participation, in general, is associated with assemblies, joined to the practices of self-management decision-making as an expression of a high participation. The Cooperative General Assembly, as the highest instance of participation, and the Board of Directors are the prevalent forms of participation. In relation to learning, Argentine workers’ recuperated enterprises provided categories of great significance to the process of socialization of knowledge: collective knowledge and knowledge cooperation, recovery of knowledge and training workers for replacement. Based on categories arising from the Argentine experience, theoretical framework and the interest of the Venezuelan workers the assessment of both, their degree of participation on technical improvements and the associated technological learning were made considering a fuzzy approach, given the ambiguous nature of these categories that were worked as sets rather than variables. It was found that participation is configured as a subset of learning to contribute to its strengthening. The conditions and relations to strengthen participation in technology issues emerged from the systematization and synthesis of both experiences (Venezuela and Argentina) combining a structure which provides training for the nucleation of collectives of knowledge (improvement projects or innovations), affinity networks, systematization of their own expertise and institutional links. These results show the integration of the interests of stakeholders (workers, researchers, institutions) through strategies like meetings, systematization of their own methods, forming ‘collectives of technological knowledge’ and a participative action research network in this industry (Industrial PAR) considering the ‘research drift’, under their own practical-theoretical discourses positioned as a possibility of their participation in technological activities in their respective organizations, opening an opportunity for scaling to other areas and sectors.

Knowledge-action integration through the media in indigenous communities in Ecuador

The binomial knowledge/action understood under the biunivocal relationship of both components is the basis of planning from a postmodern approach. Within this binomial, social communication gives appropriate information, nurtures the knowledge that leads to transformative action, promotes participation and enhances the community?s self-esteem and recognition; to deeply reflect on action is a source of new knowledge; and communication fosters the adoption of the new knowledge by the community with new actions that feed the process knowledge/action as a planning source. From this approach the project Radio Message is born as a new communication channel with the aim of offering Andean indigenous communities from the area of Cayambe (Ecuador), a series of multidisciplinary training programs that enable transformative action with a strong effect on the life quality in these communities and their importance as social actors. The contents are designed through participatory communication between the training authorities and the communities themselves, analyzing their opportunities and needs. In this research the impact of social media in the development of more than 100 indigenous communities in Cayambe is analyzed.

A CONSTRUÇÃO DO PROJETO POLÍTICO PEDAGÓGICO NUMA PERSPECTIVA DEMOCRÁTICA: UMA EXPERIÊNCIA NA REDE MUNICIPAL DE ENSINO EM SANTO ANDRÉ, SP

Este estudo aborda os esforços para a democratização das escolas da rede municipal de Santo André (SP) e as políticas públicas implementadas para atingir esse fim no período de 1997 a 2008, tendo como foco principal a construção do projeto político pedagógico como alternativa democrática e buscando identificar a criação de mecanismos que corroboraram com essa construção. De caráter qualitativo, a pesquisa desenvolveu um trabalho de campo pautado na investigação dos documentos produzidos no período, realizou entrevistas, aplicou questionários e utilizaram-se grupos focais, a fim de que os dados possibilitassem uma reflexão teórica e uma análise dialogal sobre a temática escolhida. Apresenta-se um estudo bibliográfico ancorado nas idéias de Antonio Gramsci, o teórico da hegemonia cultural, que inspirou a caminhada em direção à democratização. Procura-se encontrar, ao longo desta pesquisa, o movimento contra-hegemônico que possa indicar sinais de possíveis mudanças na escola e sua contribuição com a construção de um espaço democrático. O projeto político pedagógico é visto como referência para o diálogo, e discutem-se sua elaboração, acompanhamento e avaliação com base no conceito de "qualidade negociada" a partir das contribuições de Luiz Carlos de Freitas. Também se expõem contribuições de autores econhecidos no meio acadêmico que pesquisam a temática em pauta, trazendo à tona a dinâmica contraditória e conflituosa para a instauração de processos participativos em um país de tradição autoritária como o Brasil. A análise dos dados permitiu apresentar e reconhecer os limites da gestão escolar historicamente centralizada e hierarquizada, observando neste processo a criação de mecanismos de participação para que uma nova cultura de gestão da escola seja construída. A pesquisa elucida a importância da construção do lugar do convívio ou seja, de luta, segundo Gramsci, e de fronteira, segundo Freitas , espaço que pode permitir a criação das possibilidades de atuação social construídas pela sociedade política e pela sociedade civil.(AU)

A CONSTRUÇÃO DO PROJETO POLÍTICO PEDAGÓGICO NUMA PERSPECTIVA DEMOCRÁTICA: UMA EXPERIÊNCIA NA REDE MUNICIPAL DE ENSINO EM SANTO ANDRÉ, SP

Este estudo aborda os esforços para a democratização das escolas da rede municipal de Santo André (SP) e as políticas públicas implementadas para atingir esse fim no período de 1997 a 2008, tendo como foco principal a construção do projeto político pedagógico como alternativa democrática e buscando identificar a criação de mecanismos que corroboraram com essa construção. De caráter qualitativo, a pesquisa desenvolveu um trabalho de campo pautado na investigação dos documentos produzidos no período, realizou entrevistas, aplicou questionários e utilizaram-se grupos focais, a fim de que os dados possibilitassem uma reflexão teórica e uma análise dialogal sobre a temática escolhida. Apresenta-se um estudo bibliográfico ancorado nas idéias de Antonio Gramsci, o teórico da hegemonia cultural, que inspirou a caminhada em direção à democratização. Procura-se encontrar, ao longo desta pesquisa, o movimento contra-hegemônico que possa indicar sinais de possíveis mudanças na escola e sua contribuição com a construção de um espaço democrático. O projeto político pedagógico é visto como referência para o diálogo, e discutem-se sua elaboração, acompanhamento e avaliação com base no conceito de "qualidade negociada" a partir das contribuições de Luiz Carlos de Freitas. Também se expõem contribuições de autores econhecidos no meio acadêmico que pesquisam a temática em pauta, trazendo à tona a dinâmica contraditória e conflituosa para a instauração de processos participativos em um país de tradição autoritária como o Brasil. A análise dos dados permitiu apresentar e reconhecer os limites da gestão escolar historicamente centralizada e hierarquizada, observando neste processo a criação de mecanismos de participação para que uma nova cultura de gestão da escola seja construída. A pesquisa elucida a importância da construção do lugar do convívio ou seja, de luta, segundo Gramsci, e de fronteira, segundo Freitas , espaço que pode permitir a criação das possibilidades de atuação social construídas pela sociedade política e pela sociedade civil.(AU)

Cucumber Cotyledon Lipoxygenase during Postgerminative Growth. Its Expression and Action on Lipid Bodies

In cucumber (Cucumis sativus), high lipoxygenase-1 (LOX-1) activity has been detected in the soluble fraction prepared from cotyledons of germinating seeds, and the involvement of this enzyme in lipid turnover has been suggested (K. Matsui, M. Irie, T. Kajiwara, A. Hatanaka [1992] Plant Sci 85: 23–32; I. Fuessner, C. Wasternack, H. Kindl, H. Kühn [1995] Proc Natl Acad Sci USA 92: 11849–11853). In this study we have investigated the expression of the gene lox-1, corresponding to the LOX-1 enzyme. LOX-1 expression is highly coordinated with that of a typical glyoxysomal enzyme, isocitrate lyase, during the postgerminative stage of cotyledon development. In contrast, although icl transcripts accumulated in tissue during in vitro senescence, no accumulation of lox-1 mRNA could be observed, suggesting that lox-1 plays a specialized role in fat mobilization. LOX-1 is also known to be a major lipid body protein. The partial peptide sequences of purified LOX-1 and lipid body LOX-1 entirely coincided with that deduced from the lox-1 cDNA sequence. The data strongly suggest that LOX-1 and lipid body LOX-1 are derived from a single gene and that LOX-1 can exist both in the cytosol and on the lipid bodies. We constructed an in vitro oxygenation system to address the mechanism of this dual localization and to investigate the action of LOX-1 on lipids in the lipid bodies. LOX-1 cannot act on the lipids in intact lipid bodies, although degradation of lipid body proteins, either during seedling growth or by treatment with trypsin, allows lipid bodies to become susceptible to LOX-1. We discuss the role of LOX-1 in fat mobilization and its mechanism of action.

On the molecular mechanism of chloroquine's antimalarial action.

Chloroquine is thought to exert its antimalarial effect by preventing the polymerization of toxic heme released during proteolysis of hemoglobin in the Plasmodium digestive vacuole. The mechanism of this blockade has not been established. We incubated cultured parasites with subinhibitory doses of [3H]chloroquine and [3H] quinidine. These [3H]quinoline compounds became associated with hemozoin as assessed by electron microscope autoradiography and subcellular fractionation. In vitro, binding of [3H]quinoline inhibitors to the hemozoin chain depended on the addition of heme substrate. These data counter previous conclusions regarding the lack of quinoline association with hemozoin, explain the exaggerated accumulation of quinolines in the plasmodium digestive vacuole, and suggest that a quinoline heme complex incorporates into the growing polymer to terminate chain extension, blocking further sequestration of toxic heme.

Modeling back propagating action potential in weakly excitable dendrites of neocortical pyramidal cells.

Simultaneous recordings from the soma and apical dendrite of layer V neocortical pyramidal cells of young rats show that, for any location of current input, an evoked action potential (AP) always starts at the axon and then propagates actively, but decrementally, backward into the dendrites. This back-propagating AP is supported by a low density (-gNa = approximately 4 mS/cm2) of rapidly inactivating voltage-dependent Na+ channels in the soma and the apical dendrite. Investigation of detailed, biophysically constrained, models of reconstructed pyramidal cells shows the following. (i) The initiation of the AP first in the axon cannot be explained solely by morphological considerations; the axon must be more excitable than the soma and dendrites. (ii) The minimal Na+ channel density in the axon that fully accounts for the experimental results is about 20-times that of the soma. If -gNa in the axon hillock and initial segment is the same as in the soma [as recently suggested by Colbert and Johnston [Colbert, C. M. & Johnston, D. (1995) Soc. Neurosci. Abstr. 21, 684.2]], then -gNa in the more distal axonal regions is required to be about 40-times that of the soma. (iii) A backward propagating AP in weakly excitable dendrites can be modulated in a graded manner by background synaptic activity. The functional role of weakly excitable dendrites and a more excitable axon for forward synaptic integration and for backward, global, communication between the axon and the dendrites is discussed.

On the mechanism of action of ribonuclease A: relevance of enzymatic studies with a p-nitrophenylphosphate ester and a thiophosphate ester.

It has been reported that His-119 of ribonuclease A plays a major role as an imidazolium ion acid catalyst in the cyclization/cleavage of normal dinucleotides but that it is not needed for the cyclization/cleavage of 3'-uridyl p-nitrophenyl phosphate. We see that this is also true for simple buffer catalysis, where imidazole (as in His-12 of the enzyme), but not imidazolium ion, plays a significant catalytic role with the nitrophenyl substrate, but both are catalytic for normal dinucleotides such as uridyluridine. Rate studies show that the enzyme catalyzes the cyclization of the nitrophenylphosphate derivative 47,000,000 times less effectively (kcat/kuncat) than it does uridyladenosine, indicating that approximately 50% of the catalytic free energy change is lost with this substrate. This suggests that the nitrophenyl substrate is not correctly bound to take full advantage of the catalytic groups of the enzyme and is thus not a good guide to the mechanism used by normal nucleotides. The published data on kinetic effects with ribonuclease A of substituting thiophosphate groups for the phosphate groups of normal substrates has been discussed elsewhere, and it was argued that these effects are suggestive of the classical mechanism for ribonuclease action, not the novel mechanism we have recently proposed. The details of these rate effects, including stereochemical preferences in the thiophosphate series, can be invoked as support for our newer mechanism.

The mode of action and the structure of a herbicide in complex with its target: binding of activated hydantocidin to the feedback regulation site of adenylosuccinate synthetase.

(+)-Hydantocidin, a recently discovered natural spironucleoside with potent herbicidal activity, is shown to be a proherbicide that, after phosphorylation at the 5' position, inhibits adenylosuccinate synthetase, an enzyme involved in de novo purine synthesis. The mode of binding of hydantocidin 5'-monophosphate to the target enzyme was analyzed by determining the crystal structure of the enzyme-inhibitor complex at 2.6-A resolution. It was found that adenylosuccinate synthetase binds the phosphorylated compound in the same fashion as it does adenosine 5'-monophosphate, the natural feedback regulator of this enzyme. This work provides the first crystal structure of a herbicide-target complex reported to date.

Action spectra for phytochrome A- and B-specific photoinduction of seed germination in Arabidopsis thaliana.

We have examined the seed germination in Arabidopsis thaliana of wild type (wt), and phytochrome A (PhyA)- and B (PhyB)-mutants in terms of incubation time and environmental light effects. Seed germination of the wt and PhyA-null mutant (phyA) was photoreversibly regulated by red and far-red lights of 10-1,000 micromol m-2 when incubated in darkness for 1-14 hr, but no germination occurred in PhyB-null mutant (phyB). When wt seeds and the phyB mutant seeds were incubated in darkness for 48 hr, they synthesized PhyA during dark incubation and germinated upon exposure to red light of 1-100 nmol m-2 and far-red light of 0.5-10 micromol m-2, whereas the phyA mutant showed no such response. The results indicate that the seed germination is regulated by PhyA and PhyB but not by other phytochromes, and the effects of PhyA and PhyB are separable in this assay. We determined action spectra separately for PhyA- and PhyB-specific induction of seed germination at Okazaki large spectrograph. Action spectra for the PhyA response show that monochromatic 300-780 nm lights of very low fluence induced the germination, and this induction was not photoreversible in the range examined. Action spectra for the PhyB response show that germination was photoreversibly regulated by alternate irradiations with light of 0.01-1 mmol m-2 at wavelengths of 540-690 nm and 695-780 nm. The present work clearly demonstrated that PhyA photoirreversibly triggers the germination upon irradiations with ultraviolet, visible and far-red light of very low fluence, while PhyB controls the photoreversible effects of low fluence.

Mechanism of anti-HIV action of masked alaninyl d4T-MP derivatives.

So324 is a 2',3'-dideoxy-2',3'-didehydrothymidine-5'-monophosphate (d4T-MP) prodrug containing at the phosphate moiety a phenyl group and the methylester of alanine linked to the phosphate through a phosphoramidate linkage. So324 has anti-HIV activity in human CEM, MT4, and monocyte/macrophage cells that is superior to that of d4T. In contrast to d4T, So324 is also able to inhibit HIV replication in thymidine kinase-deficient CEM cells. After uptake of So324 by intact human lymphocytes, d4T-MP is released and subsequently converted intracellularly to d4T-TP. In addition, accumulation of substantial amounts of a novel d4T derivative has been found. This d4T metabolite has been characterized as alaninyl d4T-MP. The latter metabolite accumulates at approximately 13- to 200-fold higher levels than d4T-TP depending the experimental conditions. Alaninyl d4T-MP should be considered as an intra- and/or extracellular depot form of d4T and/or d4T-MP. These findings may explain the superior anti-retroviral activity of So324 over d4T in cell culture.