Mutant-based model of two independent pathways for carotenoid-mediated chloroplast biogenesis in Arabidopsis embryos

Chloroplasts are essential for autonomous plant growth, and their biogenesis is a complex process requiring both plastid and nuclear genome. One of the essential factors required for chloroplast biogenesis are carotenoids. Carotenoids are synthesized in plastids, and it was shown that plastid localized methylerythritol 4-phosphate (MEP) pathway provides substrates for their biosynthesis. Here, we propose a model, using results of our own mutant analysis combined with the results of others, that a MEP-independent pathway, likely a mevalonate (MVA)-dependent pathway, provides intermediates for chloroplast biogenesis in Arabidopsis embryos. The pattern of this chloroplast biogenesis differs from the MEP-dependent chloroplast biogenesis. In MEP-dependent chloroplast biogenesis, chloroplasts are formed rather uniformly in the whole embryo, with stronger chlorophyll accumulation in cotyledons. In a MEP-independent pathway, chloroplasts are formed predominantly in the hypocotyl and in the embryonic root. We also show that this pattern of chlorophyll accumulation is common to MEP pathway mutants as well as to the mutant lacking geranylgeranyl diphosphate synthase 11 (GGPPS11) activity in plastids but expressing it in the cytosol (GGPPS11cyt). It was recently described that shorter GGPPS11 transcripts are present in Arabidopsis, and they can be translated into active cytosolic proteins. We therefore propose that the MEP-independent pathway for chloroplast biogenesis in Arabidopsis embryos is an MVA pathway that provides substrates for the synthesis of GGPP via GGPPS11cyt and this is then transported to plastids, where it is used for carotenoid biosynthesis and subsequently for chloroplast biogenesis mainly in the hypocotyl and in the embryonic root

Novel Glycomimetics: Anomeric and N-Glycosyl Sulfonamides

Native glycosidic bonds in carbohydrates, are sensitive to the presence of enzymes. Thus, design of small molecule mimics (glycomimetics) is an active area of research.This review will focus on the development of a new class of glycomimetics: anomeric and N-glycosyl sulfonamides. These novel compounds have been demonstrated to be enzyme inhibitors or antiproliferative agents.Fil: Colinas, Pedro Alfonso. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Laboratorio de Estudio de Compuestos Orgánicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Verdad y misterio en la palabra

Sin resume

Coenzymes and the primary and specialized metabolism interface

In plants, primary and specialized metabolism have classically been distinguished as either essential for growth or required for survival in a particular environment. Coenzymes (organic cofactors) are essential for growth but their importance to specialized metabolism is often not considered. In line with the recent proposal of viewing primary and specialized metabolism as an integrated whole rather than segregated lots with a defined interface, we highlight here the importance of collating information on the regulation of coenzyme supply with metabolic demands using examples of vitamin B derived coenzymes. We emphasize that coenzymes can have enormous influence on the outcome of metabolic as well as engineered pathways and should be taken into account in the era of synthetic biology

Empirical models for predicting the production of wild mushrooms in Scots pine (Pinus sylvestris L.) forests in the Central Pyrenees

Mushroom picking has become a widespread autumn recreational activity in the Central Pyrenees and other regions of Spain. Predictive models that relate mushroom production or fungal species richness with forest stand and site characteristics are not available. This study used mushroom production data from 24 Scots pine plots over 3 years to develop a predictive model that could facilitate forest management decisions when comparing silvicultural options in terms of mushroom production. Mixed modelling was used to model the dependence of mushroom production on stand and site factors. The results showed that productions were greatest when stand basal area was approximately 20 m2 ha-1. Increasing elevation and northern aspect increased total mushroom production as well as the production of edible and marketed mushrooms. Increasing slope decreased productions. Marketed Lactarius spp., the most important group collected in the region, showed similar relationships. The annual variation in mushroom production correlated with autumn rainfall. Mushroom species richness was highest when the total production was highest.La cueillette de champignons est devenue une activité de loisir très répandue dans les Pyrénées centrales ainsi que dans d'autres régions d'Espagne. Aucun modèle prédictif de production ou de richesse en espèces en fonction des caractéristiques des peuplements et des stations n'est disponible actuellement. La présente étude s'est basée sur des données de récolte de champignons de 24 placettes de pin sylvestre suivies pendant 3 ans pour développer un modèle prédictif pouvant servir de modèle d'aide à la décision pour des opérations de gestion forestière. Un modèle mixte a été mis en oeuvre pour analyser les relations entre facteurs stationnels et de peuplement. Les résultats montrent que la production était maximale quand la surface terrière était de l'ordre de 20 m2 ha-1. La production totale ainsi que celle de champignons comestibles et commercialisables augmentaient avec l'altitude et dans les pentes orientées au nord. Le groupe des Lactaires (Lactarius spp.) le plus important champignon commercialisable de la région, présentait des réponses similaires. La variabilité interannuelle de production était étroitement corrélée à celle des pluies automnales. La richesse en espèce était étroitement corrélée à la production totale