Search results for "Photosynthesis"

The organic air pollutant cumene hydroperoxide interferes with NOantioxidant role in rehydrating lichen

2013

Organic pollutants effects on lichens have not been addressed. Rehydration is critical for lichens, a burst of free radicals involving NO occurs. Repeated dehydrations with organic pollutants could increase oxidative damage. Our aim is to learn the effects of cumene hydroperoxide (CP) during lichen rehydration using Ramalina farinacea (L.) Ach., its photobiont Trebouxia spp. and Asterochloris erici. Confocal imaging shows intracellular ROS and NO production within myco and phycobionts, being the chloroplast the main source of free radicals. CP increases ROS, NO and lipid peroxidation and reduces chlorophyll autofluorescence, although photosynthesis remains unaffected. Concomitant NO inhibit…

Different strategies to achieve Pb-tolerance by the two Trebouxia algae coexisting in the lichen Ramalina farinacea.

2012

Lichen thalli are permeable to airborne substances, including heavy metals, which are harmful to cell metabolism. Ramalina farinacea shows a moderate tolerance to Pb. This lichen comprises two Trebouxia phycobionts, provisionally referred to as TR1 and TR9, with distinct physiological responses to acute oxidative stress. Thus, there is a more severe decay in photosynthesis and photosynthetic pigments in TR1 than in TR9. Similarly, under oxidative stress, antioxidant enzymes and HSP70 protein decrease in TR1 but increase in TR9. Since Pb toxicity is associated with increased ROS formation, we hypothesized greater Pb tolerance in this phycobiont. Accordingly, the aim of the present study was …

Seasonal and Inter-annual Variation of Evapotranspiration in Amazonia Based on Precipitation, River Discharge and Gravity Anomaly Data

2019

We analyzed seasonal and spatial variations of evapotranspiration (ET) for five Amazon sub-basins and their response to the 2015/16 El Nino episode using a recently developed water-budget approach. ET varied typically between similar to 7 and 10 cm/month with exception of the Xingu basin for which it varied between 10 and 15 cm/month. Outstanding features of ET seasonality are (i) generally weak seasonality, (ii) two ET peaks for the two very wet catchments Solimoes and Negro, with one occurring during the wet season and one during the drier season, and (iii) a steady increase of ET during the second half of the dry season for the three drier catchments (Madeira, Tapajos, Xingu). Peak ET oc…

Selective Stepwise Suzuki Cross-Coupling Reaction for the Modelling of Photosynthetic Donor−Acceptor Systems

2009

A Suzuki reaction performed as a selective stepwise substitution of two boryl groups on a diarylporphyrin precursor is reported for straightforward construction of a porphyrin trimer, modeling photosynthetic donor-acceptor systems.

Photosynthesis mediates expression of Sorghum bicolor transporters in arbuscular mycorrhizal symbiosis

2014

Identifying a marine microalgae with high carbohydrate productivities under stress and potential for efficient flocculation

2018

Microalgal biomass represents a potential third generation feedstock that could be utilised as a source of carbohydrates for fermentative production of a range of platform biochemicals. Identifying microalgal strains with high biomass and carbohydrate productivities while also being amenable to downstream processes is key in improving the feasibility of these processes. Utilising marine microalgae capable of growing in seawater will decrease reliance on freshwater resources and improve the sustainability of production. This study screened several marine microalgae believed to accumulate carbohydrates to find new high performing strains. Four strains had high growth rates and accumulated car…

Photosynthesis and Transpiration in Damaged and Undamaged Spruce Trees

1996

Abstract The investigations presented here focus on the CO2/H2O gas exchange in damaged and undamaged spruce trees while using open-air measurements as well as measurements under defined conditions in the laboratory. The studies were performed at two different sites in the Hunsrück and the Westerwald mountains. In the laboratory the CO2/H2O gas exchange was measured on detached branches under controlled conditions in the course of two years. CO2 saturation curves were also generated. In addition CO2 compensation points were deter­ mined employing a closed system. In the natural habitat diurnal course measurements of photosynthesis and transpiration as well as light-saturation curves for pho…

Die Wirkung unterschiedlicher Lichtintensitäten während der Anzucht auf die CO2-Kompensationslage, die Glykolsäure-Oxidase- und Ribulosebiphosphat-Ca…

1978

Summary Sinapis alba (white mustard) plants were grown under conditions of strong (100 W · m -2 ) and weak (3 W · m -2 ) light and the effect of the light intensity during growth on the CO 2 -compensation point and the activities of glycolic acid oxidase and ribulose bisphosphate carboxylase were studied. The CO 2 -compensation concentration was determined according to two methods: firstly in a closed system with an infrared CO 2 -analyzer, and secondly according to the curve of net photosynthesis as a function of C0 2 -concentration over the range of 400 vpm CO 2 to the CO 2 -compensation point (Fig. 4). The intensity of light during growth was observed to exert an unmistakable effect on t…

Growth and biomass partitioning of Arbutus unedo, Laurus nobilis, Phillyrea angustifolia and Rhamnus alaternus seedlings under water deficit

2013

Water scarcity in the Mediterranean areas is very common and the selection of drought tolerant species is a priority for landscaping purposes in the Mediterranean areas. The objective of this study was to evaluate the effect of water deficit on growth and biomass partitioning of Arbutus unedo, Laurus nobilis, Phillyrea angustifolia and Rhamnus alaternus. Seventy-two seedlings per species were grown in the greenhouse in 4-liter pots and three water regimes were imposed starting on 6 April and until 9 June, 2010. One-third of the plants was well irrigated to maintain soil water content in the 25-35% range (CTR); a second group of plants was deficit-irrigated to maintain soil water content in …

Arthropod-induced neoplastic formations on trees change photosynthetic pigment levels and oxidative enzyme activities

2005

Abstract In order to test the hypothesis that arthropod-induced neoplastic formations on trees affect biochemical characteristics of both the newly formed galls and host plant tissues, biochemical characteristics with a possible adaptive role were determined in nine gall-former–host tree combinations. Photosynthetic pigments, extractable protein content, and oxidative enzyme activities were determined in gall tissues, leaf tissues of galled leaves, and leaves on ungalled tree branches. Neoplastic tissues were characterized by a low content of photosynthetic pigments, decreased chlorophyll a/b ratio, lower extractable protein content, and decreased activities of peroxidase and polyphenol oxi…