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131.
Markus F. Weber Gabriele Poxleitner Elke Hebisch Erwin Frey Madeleine Opitz 《Journal of the Royal Society Interface》2014,11(96)
Dispersal of species is a fundamental ecological process in the evolution and maintenance of biodiversity. Limited control over ecological parameters has hindered progress in understanding of what enables species to colonize new areas, as well as the importance of interspecies interactions. Such control is necessary to construct reliable mathematical models of ecosystems. In our work, we studied dispersal in the context of bacterial range expansions and identified the major determinants of species coexistence for a bacterial model system of three Escherichia coli strains (toxin-producing, sensitive and resistant). Genetic engineering allowed us to tune strain growth rates and to design different ecological scenarios (cyclic and hierarchical). We found that coexistence of all strains depended on three strongly interdependent factors: composition of inoculum, relative strain growth rates and effective toxin range. Robust agreement between our experiments and a thoroughly calibrated computational model enabled us to extrapolate these intricate interdependencies in terms of phenomenological biodiversity laws. Our mathematical analysis also suggested that cyclic dominance between strains is not a prerequisite for coexistence in competitive range expansions. Instead, robust three-strain coexistence required a balance between growth rates and either a reduced initial ratio of the toxin-producing strain, or a sufficiently short toxin range. 相似文献
132.
Ioannis-Dimosthenis S. Adamakis Ilektra Sperdouli Anetta Han Anelia Dobrikova Emilia Apostolova Michael Moustakas 《International journal of molecular sciences》2021,22(1)
Five-day exposure of clary sage (Salvia sclarea L.) to 100 μM cadmium (Cd) in hydroponics was sufficient to increase Cd concentrations significantly in roots and aboveground parts and affect negatively whole plant levels of calcium (Ca) and magnesium (Mg), since Cd competes for Ca channels, while reduced Mg concentrations are associated with increased Cd tolerance. Total zinc (Zn), copper (Cu), and iron (Fe) uptake increased but their translocation to the aboveground parts decreased. Despite the substantial levels of Cd in leaves, without any observed defects on chloroplast ultrastructure, an enhanced photosystem II (PSII) efficiency was observed, with a higher fraction of absorbed light energy to be directed to photochemistry (ΦPSΙΙ). The concomitant increase in the photoprotective mechanism of non-photochemical quenching of photosynthesis (NPQ) resulted in an important decrease in the dissipated non-regulated energy (ΦNO), modifying the homeostasis of reactive oxygen species (ROS), through a decreased singlet oxygen (1O2) formation. A basal ROS level was detected in control plant leaves for optimal growth, while a low increased level of ROS under 5 days Cd exposure seemed to be beneficial for triggering defense responses, and a high level of ROS out of the boundaries (8 days Cd exposure), was harmful to plants. Thus, when clary sage was exposed to Cd for a short period, tolerance mechanisms were triggered. However, exposure to a combination of Cd and high light or to Cd alone (8 days) resulted in an inhibition of PSII functionality, indicating Cd toxicity. Thus, the rapid activation of PSII functionality at short time exposure and the inhibition at longer duration suggests a hormetic response and describes these effects in terms of “adaptive response” and “toxicity”, respectively. 相似文献
133.
Yi-Ming Zhao Shikha Ojha Catherine M. Burgess Da-Wen Sun Brijesh K. Tiwari 《International Journal of Food Science & Technology》2021,56(2):721-732
This study aimed to evaluate the influence of plasma treatment time, bacterial exposure time to PAW and bacterial species on the inactivation efficacy of plasma-activated water (PAW), with additional investigation of the inactivation mechanisms of PAW. Six bacterial species, including Listeria innocua, Staphyloccus aureus, Escherichia coli, Pseudomonas fluorescens, Shewanella putrefaciens and Aeromonas hydrophila were selected as the representative bacteria. The initial bacterial concentration was around 7 log CFU ml−1 after mixing with PAW, and the inactivation efficacy was measured after different exposure times during the 4 °C storage. Scanning electron microscopy (SEM) images of the bacteria after PAW treatment were carried out to inspect the cell structure damage, and physicochemical properties of PAW, including pH, conductivity and long-living reactive species of H2O2, , and , were examined. The results showed that the inactivation efficacy of PAW was positively correlated with plasma treatment time and bacterial exposure time, and for the species examined in this study, the Gram-negative species were more sensitive to PAW than the Gram-positive species. Cell structure damage, including shrinkage, distortion, or holes, was observed after PAW treatment. The pH of PAW was acidified to 2.5–2.9, and conductivity was significantly increased to 518.0 μs cm−1. and H2O2 were reduced during the 48 h storage, while an increased concentration was observed for . This study demonstrated that the processing parameters of plasma treatment time, exposure time and characteristics of bacteria can significantly affect the inactivation efficacy of PAW. 相似文献
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137.
Jane Roche Zephirin Mouloungui Muriel Cerny Othmane Merah 《International Journal of Food Science & Technology》2016,51(8):1820-1826
This study was carried out to compare the kinetic accumulation of bioactive lipids during seed development in three oil crops rapeseed, sunflower and woad. Field experiments were conducted under organic conditions during 3 years. After flowering, seeds were collected each 4–5 days until harvest. The three species differed by the quantity and quality of both fatty acids and sterols. Higher levels of phytosterols and fatty acids were reached between 20 and 40 days after flowering (DAF) in sunflower, 40 and 60 DAF in rapeseed and 25 and 45 DAF for woad. The modification of lipid composition during the grain filling depends on species. Knowledge of the composition and accumulation of fatty acids and phytosterols in sunflower, rapeseed and woad seeds would assist in efforts to achieve industrial applications. These seeds may give an interesting source of bioactive lipids. 相似文献
138.
Karolina W. Cynk 《Civil Engineering and Environmental Systems》2017,34(2):104-126
The aim of this article was to characterise and compare the level of environmental intelligence among university students from selected countries of Central and Eastern Europe. This was done using empirical data collected by the author in 2015. In the introduction and theoretical part of this text, the term ‘environmental intelligence’ is defined, and issues raised by modern sociologists such as M. Maffesoli and M. Archer are presented. Two hypotheses stating that respondents from Poland, Slovakia and Czech Republic have higher levels of environmental intelligence than university students from the Ukraine, and those studying natural sciences have higher levels of environmental intelligence than students of the humanities or social sciences were verified. The statistical analysis conducted in the second part of the text revealed a higher level of environmental intelligence among students from the European Union countries compared to respondents from the Ukraine. However, there were no significant differences between the level of environmental intelligence and respondents’ faculty of studies. This indicates that studying natural sciences did not contribute to a more dynamic development of environmental intelligence in students. This revelation may be disturbing, as the state of the environment cannot improve if young people cannot use and care for it responsibly. 相似文献
139.
《工业材料与腐蚀》2017,68(11):1160-1171
140.
The paper considers a network of agents with multiple‐integrator internal dynamics, which share partial information on their states according to an arbitrary topology. For this system, two control problems are addressed and solved. The first consists in assigning the dominant closed‐loop poles. The second consists in achieving a specified consensus with arbitrary dominant dynamics. In both cases, the regulator is required to be decentralized, and the controlled network has to result tolerant with respect to faults in the communication apparatuses of the agents. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献