Long-term relationships among atmospheric CO2, stomata, and intrinsic water use efficiency in individual trees

Leaf-level responses to increases in atmospheric carbon dioxide (CO(2)) concentrations could have large implications for water and carbon cycles. We investigated whether stomatal density, guard cell length, and intrinsic water use efficiency (iWUE) of 27 individual trees growing at the Arnold Arboretum in Boston, Massachusetts have responded to changing environmental conditions over the last 100 years. We examined leaves from 74 herbarium specimens collected from three genera-Acer (maples), Quercus (oaks), and Carpinus (hornbeams)-from 1893 to 2006. During this period, global average atmospheric CO(2) concentrations increased by approximately 29% (86 ppm), and temperatures in Boston increased by 1.8°C. Stomatal density and guard cell length were negatively correlated in oaks and hornbeams. Although stomatal density declined and guard cell length increased over time, the changes were not dependent on the magnitude of changes in CO(2) concentrations. Intrinsic WUE did not change significantly over time. Our findings suggest that iWUE may not respond to changes in CO(2) concentrations over the lifetimes of individual trees, possibly because of compensating changes in stomatal density and guard cell size. We provide an example of a method that can enable researchers to differentiate between genetic and plastic responses to global change in long-lived trees.     

Water-soluble formulation of Coenzyme Q10 inhibits Bax-induced destabilization of mitochondria in mammalian cells

Oxidative stress leads to mitochondrial dysfunction, which triggers the opening of the permeability transition pores (PTP) and the release of pro-apoptotic factors causing apoptotic cell death. In a limited number of cell systems, anti-oxidants and free-radical scavengers have been shown to block this response. We have previously reported that coenzyme Q₁₀ (CoQ₁₀), an electron carrier in the mitochondrial respiratory chain, is involved in the reactive oxygen species (ROS) removal and prevention of oxidative stress-induced apoptosis in neuronal cells. However, the mechanism of this protection has not been fully elucidated. In the present study we investigated the effects of CoQ₁₀ on the mitochondrial events characteristic to apoptosis, especially on the function of pro-apoptotic protein Bax. Our results demonstrated that following a brief exposure of two human cell lines (fibroblasts and HEK293 cells) to H₂O₂ the intracellular levels of ROS and the association of Bax with the mitochondria significantly increased and the cells underwent apoptosis. Both of these events, as well as the release of cytochrome c from the mitochondria, were blocked by a 24 h pre-treatment with CoQ₁₀. It is therefore believed that CoQ₁₀ prevented the collapse of the mitochondrial membrane potential in response to the H₂O₂ treatment. Recombinant Bax protein alone caused the ROS generation and release of cytochrome c from isolated mitochondria and, again, CoQ₁₀ inhibited these Bax-induced mitochondrial dysfunctions.     

Interaction effect of sulphur and molybdenum on the uptake and utilization of these elements by raya (Brassica juncea L.)

Summary Molybdenum applied alone and in combination with sulphur was found to be readily available toBrassica juncea plants grown on loam soil moderate in available Mo (0.122 ppm) Molybdenum accumulated several times more in the vegetative portion as compared to the grain. Recovery of the applied molybdenum decreased with increase in dose of applied molybdenum.Application of 50 ppm S depressed the molybdenum content in plants to one third, when compared to its concentration in the absence of sulphur. The effect of sulphur in depressing the molybdenum concentration in plants was more conspicuous where molybdenum was applied alongwith sulphur.     

Isolation of a gene that down-regulates nitrate assimilation and influences another regulatory gene in the same system.

Glutamine is the preferred source of nitrogen of Neurospora crassa. In its presence and that of the gene product of MS5 (nmr-1), the fungus represses the assimilation of less preferred forms of nitrogen, such as nitrate. In the absence of glutamine and the presence of the product of gene nit-2, less preferred forms of nitrogen are assimilated as long as a specific pathway for their assimilation is induced. We report here the isolation, from a cosmid bank, of a gene that complements MS5 and can also complement nit-2. We speculate that this result suggests an interaction between the MS5 and nit-2 gene products and that this is important in the regulation of nitrate assimilation.     

Development and characterization of genic SSR-FDM for stem gall disease resistance in coriander (Coriandrum sativum L.) and its cross species transferability

Molecular Biology Reports - Coriander (Coriandrum sativum L.) is well known vegetable and spice crop grown globally for its leaves and seeds. Stem gall (Protomyces macrosporus L.) is a fungal...     

Influence of sulphur fertilization on suppression of molybdenum uptake by berseem (Trifolium alexandrinum L.) and oats (Avena sativa L.) grown on a molybdenumtoxic soil

Summary Berseem (Trifolium alexandrinum L.) and oats (Avena satina L.) were grown in a greenhouse on a soil with a toxic level of available molybdenum. Significant increase in yield of berseem was observed on application of phosphorus and sulphur. The oat crop responded only to P application. The content of Mo in plants was enhanced by application of phosphorus. The application of sulphur depressed the Mo content of plants. The effect of P application was more conspicuous than the depressing effect of S application on Mo content of plants. The decrease in Mo content with S application was more pronounced in the oat crop. An application of 100 ppm S as gypsum caused 57.6 per cent decrease in the concentration of Mo which was below the threshhold toxic level. But in berseem, an application of 100 ppm S even could not lower the Mo concentration to a safer level. Gypsum and superphosphate were equally effective in lowering the concentration of Mo in berseem.Published as no 2 in the series: Molybdenum accumulation in forage crops, by the same authors.College of Agriculture and Radiation Soil Chemist, respectively.     

Malic enzyme 2 connects the Krebs cycle intermediate fumarate to mitochondrial biogenesis

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