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Fuentes D.,University of Santiago de Chile | Meneses M.,University of Santiago de Chile | Nunes-Nesi A.,Max Planck Institutfur Molekulare Pflanzenphysiologie | Nunes-Nesi A.,Federal University of Vicosa | And 9 more authors.
Plant Physiology | Year: 2011

Mitochondrial complex II (succinate dehydrogenase [SDH]) plays roles both in the tricarboxylic acid cycle and the respiratory electron transport chain. In Arabidopsis (Arabidopsis thaliana), its flavoprotein subunit is encoded by two nuclear genes, SDH1-1 and SDH1-2. Here, we characterize heterozygous SDH1-1/sdh1-1 mutant plants displaying a 30% reduction in SDH activity as well as partially silenced plants obtained by RNA interference. We found that these plants displayed significantly higher CO 2 assimilation rates and enhanced growth than wild-type plants. There was a strong correlation between CO 2 assimilation and stomatal conductance, and both mutant and silenced plants displayed increased stomatal aperture and density. By contrast, no significant differences were found for dark respiration, chloroplastic electron transport rate, CO 2 uptake at saturating concentrations of CO 2, or biochemical parameters such as the maximum rates of carboxylation by Rubisco and of photosynthetic electron transport. Thus, photosynthesis is enhanced in SDH-deficient plants by a mechanism involving a specific effect on stomatal function that results in improved CO 2 uptake. Metabolic and transcript profiling revealed that mild deficiency in SDH results in limited effects on metabolism and gene expression, and data suggest that decreases observed in the levels of some amino acids were due to a higher flux to proteins and other nitrogen-containing compounds to support increased growth. Strikingly, SDH1-1/ sdh1-1 seedlings grew considerably better in nitrogen-limiting conditions. Thus, a subtle metabolic alteration may lead to changes in important functions such as stomatal function and nitrogen assimilation. © 2011 American Society of Plant Biologists. All Rights Reserved.

Meneses C.,Andres Bello University | Orellana A.,Andres Bello University | Orellana A.,Center for Genome Regulation
Biological Research | Year: 2013

New fruit varieties are needed to satisfy consumers, and the industry is facing new challenges in order to respond to these demands. The emergence of genomic tools is releasing information on polymorphisms that can be utilized to expedite breeding processes in species that are difficult to breed, given the long periods of time required to get new varieties. The present review describes the current stages of the ongoing efforts that are being taken to apply these technologies to obtain varieties with improved fruit quality in species of the family Rosaceae.

Klein A.D.,Weizmann Institute of Science | Alvarez A.,University of Santiago de Chile | Zanlungo S.,University of Santiago de Chile | Zanlungo S.,Center for Genome Regulation
Pediatric Endocrinology Reviews | Year: 2014

Niemann-Pick type C disease (NPC) is a neurovisceral lysosomal cholesterol storage disorder that arises from loss-of-function mutations in either the NPC1 or NPC2 genes. Both genes code for proteins involved in lysosomal cholesterol efflux. NPC is often diagnosed in early childhood, with patients typically displaying cerebellar ataxia, difficulties in speaking and swallowing, and progressive dementia. Unfortunately, to date, there is no curative treatment for this devastating and fatal disorder, although several symptomatic manifestations of NPC are treatable. In this review, we discuss the cell biology of the disease, clinical aspects, diagnostic approaches, and current and potential therapeutic strategies against NPC.

Vazquez M.C.,University of Santiago de Chile | Balboa E.,University of Santiago de Chile | Alvarez A.R.,University of Santiago de Chile | Zanlungo S.,University of Santiago de Chile | Zanlungo S.,Center for Genome Regulation
Oxidative Medicine and Cellular Longevity | Year: 2012

Niemann-Pick type C (NPC) disease is a neurovisceral atypical lipid storage disorder involving the accumulation of cholesterol and other lipids in the late endocytic pathway. The pathogenic mechanism that links the accumulation of intracellular cholesterol with cell death in NPC disease in both the CNS and the liver is currently unknown. Oxidative stress has been observed in the livers and brains of NPC mice and in different NPC cellular models. Moreover, there is evidence of an elevation of oxidative stress markers in the serumof NPC patients. Recent evidence strongly suggests that mitochondrial dysfunction plays an important role in NPC pathogenesis and that mitochondria could be a significant source of oxidative stress in this disease. In this context, the accumulation of vitamin E in the late endosomal/lysosomal compartments in NPC could lead to a potential decrease of its bioavailability and could be another possible cause of oxidative damage. Another possible source of reactive species in NPC is the diminished activity of different antioxidant enzymes. Moreover, because NPC is mainly caused by the accumulation of free cholesterol, oxidized cholesterol derivatives produced by oxidative stress may contribute to the pathogenesis of the disease. Copyright © 2012 Mary Carmen Vzquez et al.

Kraiser T.,Center for Genome Regulation | Gras D.E.,Center for Genome Regulation | Gutierrez A.G.,Helmholtz Center for Environmental Research | Gonzalez B.,University of Santiago de Chile | Gutierrez R.A.,Center for Genome Regulation
Journal of Experimental Botany | Year: 2011

Nitrogen (N) is the mineral nutrient required in the greatest amount and its availability is a major factor limiting growth and development of plants. As sessile organisms, plants have evolved different strategies to adapt to changes in the availability and distribution of N in soils. These strategies include mechanisms that act at different levels of biological organization from the molecular to the ecosystem level. At the molecular level, plants can adjust their capacity to acquire different forms of N in a range of concentrations by modulating the expression and function of genes in different N uptake systems. Modulation of plant growth and development, most notably changes in the root system architecture, can also greatly impact plant N acquisition in the soil. At the organism and ecosystem levels, plants establish associations with diverse microorganisms to ensure adequate nutrition and N supply. These different adaptive mechanisms have been traditionally discussed separately in the literature. To understand plant N nutrition in the environment, an integrated view of all pathways contributing to plant N acquisition is required. Towards this goal, in this review the different mechanisms that plants utilize to maintain an adequate N supply are summarized and integrated. © 2011 The Author.

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