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91.
92.
Impacts of climate variability on tree demography in second growth tropical forests: the importance of regional context for predicting successional trajectories
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María Uriarte Naomi Schwartz Jennifer S. Powers Erika Marín‐Spiotta Wenying Liao Leland K. Werden 《Biotropica》2016,48(6):780-797
Naturally regenerating and restored second growth forests account for over 70% of tropical forest cover and provide key ecosystem services. Understanding climate change impacts on successional trajectories of these ecosystems is critical for developing effective large‐scale forest landscape restoration (FLR) programs. Differences in environmental conditions, species composition, dynamics, and landscape context from old growth forests may exacerbate climate impacts on second growth stands. We compile data from 112 studies on the effects of natural climate variability, including warming, droughts, fires, and cyclonic storms, on demography and dynamics of second growth forest trees and identify variation in forest responses across biomes, regions, and landscapes. Across studies, drought decreases tree growth, survival, and recruitment, particularly during early succession, but the effects of temperature remain unexplored. Shifts in the frequency and severity of disturbance alter successional trajectories and increase the extent of second growth forests. Vulnerability to climate extremes is generally inversely related to long‐term exposure, which varies with historical climate and biogeography. The majority of studies, however, have been conducted in the Neotropics hindering generalization. Effects of fire and cyclonic storms often lead to positive feedbacks, increasing vulnerability to climate extremes and subsequent disturbance. Fragmentation increases forests’ vulnerability to fires, wind, and drought, while land use and other human activities influence the frequency and intensity of fire, potentially retarding succession. Comparative studies of climate effects on tropical forest succession across biogeographic regions are required to forecast the response of tropical forest landscapes to future climates and to implement effective FLR policies and programs in these landscapes. 相似文献
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94.
Outcrossing potential between 11 important genetically modified crops and the Chilean vascular flora
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Miguel A. Sánchez Pablo Cid Humberto Navarrete Carlos Aguirre Gustavo Chacón Erika Salazar Humberto Prieto 《Plant biotechnology journal》2016,14(2):625-637
The potential impact of genetically modified (GM) crops on biodiversity is one of the main concerns in an environmental risk assessment (ERA). The likelihood of outcrossing and pollen‐mediated gene flow from GM crops and non‐GM crops are explained by the same principles and depend primarily on the biology of the species. We conducted a national‐scale study of the likelihood of outcrossing between 11 GM crops and vascular plants in Chile by use of a systematized database that included cultivated, introduced and native plant species in Chile. The database included geographical distributions and key biological and agronomical characteristics for 3505 introduced, 4993 native and 257 cultivated (of which 11 were native and 246 were introduced) plant species. Out of the considered GM crops (cotton, soya bean, maize, grape, wheat, rice, sugar beet, alfalfa, canola, tomato and potato), only potato and tomato presented native relatives (66 species total). Introduced relative species showed that three GM groups were formed having: a) up to one introduced relative (cotton and soya bean), b) up to two (rice, grape, maize and wheat) and c) from two to seven (sugar beet, alfalfa, canola, tomato and potato). In particular, GM crops presenting introduced noncultivated relative species were canola (1 relative species), alfalfa (up to 4), rice (1), tomato (up to 2) and potato (up to 2). The outcrossing potential between species [OP; scaled from ‘very low’ (1) to ‘very high’ (5)] was developed, showing medium OPs (3) for GM–native relative interactions when they occurred, low (2) for GMs and introduced noncultivated and high (4) for the grape‐Vitis vinifera GM–introduced cultivated interaction. This analytical tool might be useful for future ERA for unconfined GM crop release in Chile. 相似文献
95.
Blimp-1-Dependent IL-10 Production by Tr1 Cells Regulates TNF-Mediated Tissue Pathology 总被引:1,自引:0,他引:1
Marcela Montes de Oca Rajiv Kumar Fabian de Labastida Rivera Fiona H Amante Meru Sheel Rebecca J. Faleiro Patrick T. Bunn Shannon E. Best Lynette Beattie Susanna S. Ng Chelsea L. Edwards Werner Muller Erika Cretney Stephen L. Nutt Mark J. Smyth Ashraful Haque Geoffrey R. Hill Shyam Sundar Axel Kallies Christian R. Engwerda 《PLoS pathogens》2016,12(1)
Tumor necrosis factor (TNF) is critical for controlling many intracellular infections, but can also contribute to inflammation. It can promote the destruction of important cell populations and trigger dramatic tissue remodeling following establishment of chronic disease. Therefore, a better understanding of TNF regulation is needed to allow pathogen control without causing or exacerbating disease. IL-10 is an important regulatory cytokine with broad activities, including the suppression of inflammation. IL-10 is produced by different immune cells; however, its regulation and function appears to be cell-specific and context-dependent. Recently, IL-10 produced by Th1 (Tr1) cells was shown to protect host tissues from inflammation induced following infection. Here, we identify a novel pathway of TNF regulation by IL-10 from Tr1 cells during parasitic infection. We report elevated Blimp-1 mRNA levels in CD4+ T cells from visceral leishmaniasis (VL) patients, and demonstrate IL-12 was essential for Blimp-1 expression and Tr1 cell development in experimental VL. Critically, we show Blimp-1-dependent IL-10 production by Tr1 cells prevents tissue damage caused by IFNγ-dependent TNF production. Therefore, we identify Blimp-1-dependent IL-10 produced by Tr1 cells as a key regulator of TNF-mediated pathology and identify Tr1 cells as potential therapeutic tools to control inflammation. 相似文献
96.
Trichoderma aureoviride URM 5158 and Trichoderma hamatum URM 6656 are Biocontrol Agents that act against Cassava Root rot through different Mechanisms
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José Aldo Teixeira da Silva Erika Valente de Medeiros Jéssica Morais da Silva Dyana de A. Tenório Keila Aparecida Moreira Talita Camila Evaristo da Silva Nascimento Cristina Souza‐Motta 《Journal of Phytopathology》2016,164(11-12):1003-1011
Trichoderma has been used to manage a large number of pathogens, but there is a gap in the mechanisms used by these biocontrol agents regarding the physiological response of cassava plants (Manihot esculenta) when it is subjected to cassava root rot. The aims of this study were to investigate the antagonist activity of ten Trichoderma isolates against Fusarium solani on potato dextrose Agar (PDA), to quantify the chitinase production, to select and test in vivo the best isolate from each experiment and to assess the physiological response of cassava to the production of oxidative enzyme complex production (ascorbate peroxidase, catalase, peroxidase and polyphenol oxidase). All Trichoderma isolates have shown competitive capability against F. solani, and Trichoderma hamatum URM 6656 showed the highest inhibition of pathogen growth (88.91%). All isolates have shown chitinase activity, but Trichoderma aureoviride URM 5158 produced the highest amount of chitinase. T. hamatum URM 6656 and T. aureoviride URM 5158 were selected to be applied in vivo. The two Trichoderma strains reduced 64 and 60% of the disease severity in the shoot and 82 and 84% in the root. Cassava plants infected with Trichoderma have shown the highest peroxidase and ascorbate peroxidase production. Our results have indicated that T. aureoviride URM 5158 is an effective biocontrol agent against cassava root rot caused by F. solani, because it presented competitive antagonist capability in vitro, the highest chitinase production, and reduced the cassava root rot severity. The application of T. aureoviride has led to the maximum enzyme activity of reactive oxygen species group in cassava plants. 相似文献
97.
Although macrophytes are known to increase benthic diversity in lakes, the importance of this resource as food for the insects living at the bottom of these ecosystems are still poorly understood. This study assessed the diets of benthic Chironomidae and Campsurus (Ephemeroptera) in two environments: a lake with macrophytes (M+) and another without macrophytes (M?). We expected a differential use of food resources in M+, where plant tissue is particularly important for the aquatic insects’ diet. The diet of 734 individuals from 16 taxa were analyzed. Contrary to expectations, benthic insects consumed low amounts of plant tissue. This finding led us to investigate whether the presence of macrophytes in lakes would indirectly contribute to the benthic insects’ feeding, as more food resources were explored in M+ and a spatial variation of resources intake was observed in this lake, in contrast to the homogeneous feeding in M?. We highlight that macrophytes were responsible for the organic matter build‐up in the sediment, especially at the lake region dominated by these plants, and contributed to increase the deposition of high‐quality amorphous organic matter, which favored taxa in M+ that fed exclusively on this item. The lower diversity of food items exploited in M?, and the Tanypus alga‐based diet in this lake, indicates the low quality of organic resources in its sediment. Although macrophytes were indirectly beneficial for benthic insects’ feeding, we found that this is not an attractive resource for prompt ingestion by most benthic taxa. 相似文献
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100.
In many ecosystems, plant growth and reproduction are nitrogen limited. Current and predicted increases of global reactive nitrogen could alter the ecological and evolutionary trajectories of plant populations. Nitrogen is a major component of nucleic acids and cell structures, and it has been predicted that organisms with larger genomes should require more nitrogen for growth and reproduction and be more negatively affected by nitrogen scarcities than organisms with smaller genomes. In a greenhouse experiment, we tested this hypothesis by examining whether the amount of soil nitrogen supplied differentially influenced the performance (fitness, growth, and resource allocation strategies) of diploid and autotetraploid fireweed (Chamerion angustifolium). We found that soil nitrogen levels differentially impacted cytotype performance, and in general, diploids were favored under low nitrogen conditions, but this diploid advantage disappeared under nitrogen enrichment. Specifically, when nitrogen was scarce, diploids produced more seeds and allocated more biomass toward seed production relative to investment in plant biomass or total plant nitrogen than did tetraploids. As nitrogen supplied increased, such discrepancies between cytotypes disappeared. We also found that cytotype resource allocation strategies were differentially dependent on soil nitrogen, and that whereas diploids adopted resource allocation strategies that favored current season reproduction when nitrogen was limiting and future reproduction when nitrogen was more plentiful, tetraploids adopted resource allocation strategies that favored current season reproduction under nitrogen enrichment. Together these results suggest nitrogen enrichment could differentially affect cytotype performance, which could have implications for cytotypes’ ecological and evolutionary dynamics under a globally changing climate. 相似文献