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111.
Effects of heat and drought stress on post‐illumination bursts of volatile organic compounds in isoprene‐emitting and non‐emitting poplar 下载免费PDF全文
Werner Jud Elisa Vanzo Ziru Li Andrea Ghirardo Ina Zimmer Thomas D. Sharkey Armin Hansel Jörg‐Peter Schnitzler 《Plant, cell & environment》2016,39(6):1204-1215
Over the last decades, post‐illumination bursts (PIBs) of isoprene, acetaldehyde and green leaf volatiles (GLVs) following rapid light‐to‐dark transitions have been reported for a variety of different plant species. However, the mechanisms triggering their release still remain unclear. Here we measured PIBs of isoprene‐emitting (IE) and isoprene non‐emitting (NE) grey poplar plants grown under different climate scenarios (ambient control and three scenarios with elevated CO2 concentrations: elevated control, periodic heat and temperature stress, chronic heat and temperature stress, followed by recovery periods). PIBs of isoprene were unaffected by elevated CO2 and heat and drought stress in IE, while they were absent in NE plants. On the other hand, PIBs of acetaldehyde and also GLVs were strongly reduced in stress‐affected plants of all genotypes. After recovery from stress, distinct differences in PIB emissions in both genotypes confirmed different precursor pools for acetaldehyde and GLV emissions. Changes in PIBs of GLVs, almost absent in stressed plants and enhanced after recovery, could be mainly attributed to changes in lipoxygenase activity. Our results indicate that acetaldehyde PIBs, which recovered only partly, derive from a new mechanism in which acetaldehyde is produced from methylerythritol phosphate pathway intermediates, driven by deoxyxylulose phosphate synthase activity. 相似文献
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Empirical evidence for large‐scale human impact on intertidal aggregations,larval supply and recruitment of Pyura praeputialis around the Bay of Antofagasta,Chile 下载免费PDF全文
Patricio H. Manríquez Juan Carlos Castilla Verónica Ortiz María Elisa Jara 《Austral ecology》2016,41(6):701-714
In northern Chile, Pyura praeputialis is an invasive species inhabiting rocky intertidal and subtidal habitats restricted exclusively to the Bay of Antofagasta where it forms extensive aggregations. The negative impact of Pyura gathering on mid‐intertidal abundances of this species has recently been reported at the south‐eastern end of this bay. In the present study we have increased sampling sites to cover the entire bay toward the north‐western end and the northern section, where a coastal marine reserve for the scallop fishery partially restricts shellfish gathering. Therefore, the sampling sites were chosen to represent different levels of shellfish gathering access along the northern shore of the bay. Long‐term monitoring (1999–2014) of changes in tunicate cover and the abundances of larvae and recruits at seven sites are reported. The opening of a remodelled artificial and recreational beach in 2012, on the central‐eastern shore of the bay, has increased accessibility to rocky intertidal platforms that started to be massively visited by Pyura gatherers from the summer of 2013. This allowed for the implementation of an intensive short‐term monitoring program of changes in tunicate cover and the abundances of their larvae and recruits. When gathering access was present the reduction in intertidal cover was generalized to the entire bay and followed by reductions in larvae and recruits. However, these reductions were not found in sites with more restricted gathering access. We conclude that continuous extraction by Pyura gatherers followed by reductions of conspecific larvae and recruits are the main drivers behind the reduced abundance of P. praeputialis in the entire bay of Antofagasta. Thus, if gathering is not stopped important ecosystem services provided by this tunicate in the bay may be threatened. Similar consequences may be expected if other massive and irreversible reductions in other species of the Pyura complex, that inhabit other coasts in the southern hemisphere, occur. The controversy concerning the impacts of invasive species and whether they cause negative, positive or neutral impacts to original ecosystems and fisheries is discussed. 相似文献
114.
Circulating ceramides are inversely associated with cardiorespiratory fitness in participants aged 54–96 years from the Baltimore Longitudinal Study of Aging 下载免费PDF全文
Elisa Fabbri An Yang Eleanor M. Simonsick Chee W. Chia Marco Zoli Norman J. Haughey Michelle M. Mielke Paul M. Coen 《Aging cell》2016,15(5):825-831
Cardiorespiratory fitness (VO2 peak) declines with age and is an independent risk factor for morbidity and mortality in older adults. Identifying biomarkers of low fitness may provide insight for why some individuals experience an accelerated decline of aerobic capacity and may serve as clinically valuable prognostic indicators of cardiovascular health. We investigated the relationship between circulating ceramides and VO2 peak in 443 men and women (mean age of 69) enrolled in the Baltimore Longitudinal Study of Aging (BLSA). Individual species of ceramide were quantified by HPLC–tandem mass spectrometry. VO2 peak was measured by a graded treadmill test. We applied multiple regression models to test the associations between ceramide species and VO2 peak, while adjusting for age, sex, blood pressure, serum LDL, HDL, triglycerides, and other covariates. We found that higher levels of circulating C18:0, C20:0, C24:1 ceramides and C20:0 dihydroceramides were strongly associated with lower aerobic capacity (P < 0.001, P < 0.001, P = 0.018, and P < 0.001, respectively). The associations held true for both sexes (with men having a stronger association than women, P value for sex interaction <0.05) and were unchanged after adjusting for confounders and multiple comparison correction. Interestingly, no significant association was found for C16:0, C22:0, C24:0, C26:0, and C22:1 ceramide species, C24:0 dihydroceramide, or total ceramides. Our analysis reveals that specific long‐chain ceramides strongly associate with low cardiovascular fitness in older adults and may be implicated in the pathogenesis of low fitness with aging. Longitudinal studies are needed to further validate these associations and investigate the relationship between ceramides and health outcomes. 相似文献
115.
Elisa Giovannetti Leticia G. Leon Valentina E. Gómez Paolo A. Zucali Filippo Minutolo 《Nucleosides, nucleotides & nucleic acids》2016,35(10-12):643-651
ABSTRACTMalignant pleural mesothelioma (MPM) is a very hypoxic malignancy, and hypoxia has been associated with resistance towards gemcitabine. The muscle-isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch to anaerobic glycolysis. Therefore we investigated the combination of a new LDH-A inhibitor (NHI-1) with gemcitabine in MPM cell lines. Under hypoxia (O2 tension of 1%) the cell growth inhibitory effects of gemcitabine, were reduced, as demonstrated by a 5- to 10-fold increase in IC50s. However, the simultaneous addition of NHI-1 was synergistic (combination index < 1). Flow cytometry demonstrated that hypoxia caused a G1 arrest, whereas the combination of NHI-1 significantly increased gemcitabine-induced cell death. Finally, the mRNA expression levels of the human equilibrative transporter-1 (hENT1) were significantly down-regulated under hypoxia, but treatment with NHI-1 was associated with a recovery of hENT1 expression. In conclusion, our data show that hypoxia increased MPM resistance to gemcitabine. However, cell death induction and modulation of the key transporter in gemcitabine uptake may contribute to the synergistic interaction of gemcitabine with the LDH-A inhibitor NHI-1 and support further studies for the rational development of this combination. 相似文献
116.
Silvia Peppicelli Alessandra Toti Elisa Giannoni Francesca Bianchini Francesca Margheri Mario Del Rosso 《Cell cycle (Georgetown, Tex.)》2016,15(14):1908-1918
Low extracellular pH promotes in melanoma cells a malignant phenotype characterized by an epithelial-to-mesenchymal transition (EMT) program, endowed with mesenchymal markers, high invasiveness and pro-metastatic property. Here, we demonstrate that melanoma cells exposed to an acidic extracellular microenvironment, 6.7±0.1, shift to an oxidative phosphorylation (Oxphos) metabolism. Metformin, a biguanide commonly used for type 2 diabetes, inhibited the most relevant features of acid-induced phenotype, including EMT and Oxphos. When we tested effects of lactic acidosis, to verify whether sodium lactate might have additional effects on acidic melanoma cells, we found that EMT and Oxphos also characterized lactic acid-treated cells. An increased level of motility was the only gained property of lactic acidic-exposed melanoma cells. Metformin treatment inhibited both EMT markers and Oxphos and, when its concentration raised to 10 mM, it induced a striking inhibition of proliferation and colony formation of acidic melanoma cells, both grown in protons enriched medium or lactic acidosis. Thus, our study provides the first evidence that metformin may target either proton or lactic acidosis-exposed melanoma cells inhibiting EMT and Oxphox metabolism. These findings disclose a new potential rationale of metformin addition to advanced melanoma therapy, e.g. targeting acidic cell subpopulation. 相似文献
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Structural and biochemical insights into 7β‐hydroxysteroid dehydrogenase stereoselectivity 下载免费PDF全文
Simone Savino Erica Elisa Ferrandi Federico Forneris Stefano Rovida Sergio Riva Daniela Monti Andrea Mattevi 《Proteins》2016,84(6):859-865
Hydroxysteroid dehydrogenases are of great interest as biocatalysts for transformations involving steroid substrates. They feature a high degree of stereo‐ and regio‐selectivity, acting on a defined atom with a specific configuration of the steroid nucleus. The crystal structure of 7β‐hydroxysteroid dehydrogenase from Collinsella aerofaciens reveals a loop gating active‐site accessibility, the bases of the specificity for NADP+, and the general architecture of the steroid binding site. Comparison with 7α‐hydroxysteroid dehydrogenase provides a rationale for the opposite stereoselectivity. The presence of a C‐terminal extension reshapes the substrate site of the β‐selective enzyme, possibly leading to an inverted orientation of the bound substrate. Proteins 2016; 84:859–865. © 2016 Wiley Periodicals, Inc. 相似文献
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Ignacio Jos Melero‐Jimnez Elena Martín‐Clemente María Jesús García‐Snchez Antonio Flores‐Moya Elena Baares‐Espaa 《Phycological Research》2019,67(3):192-201
The cyanobacterium Microcystis aeruginosa causes most of the harmful toxic blooms in freshwater ecosystems. Some strains of M. aeruginosa tolerate low‐medium levels of salinity, and because salinization of freshwater aquatic systems is increasing worldwide it is relevant to know what adaptive mechanisms allow tolerance to salinity. The mechanisms involved in the adaptation of M. aeruginosa to salinity (acclimation vs. genetic adaptation) were tested by a fluctuation analysis design, and then the maximum capacity of adaptation to salinity was studied by a ratchet protocol experiment. Whereas a dose of 10 g NaCl L?1 completely inhibited the growth of M. aeruginosa, salinity‐resistant genetic variants, capable of tolerating up to 14 g NaCl L?1, were isolated in the fluctuation analysis experiment. The salinity‐resistant cells arose by spontaneous mutations at a rate of 7.3 × 10?7 mutants per cell division. We observed with the ratchet protocol that three independent culture populations of M. aeruginosa were able to adapt to up to 15.1 g L?1 of NaCl, suggesting that successive mutation‐selection processes can enhance the highest salinity level to which M. aeruginosa cells can initially adapt. We propose that increasing salinity in water reservoirs could lead to the selection of salinity‐resistant mutants of M. aeruginosa. 相似文献