scholarly journals Escherichia coli metabolism under short-term repetitive substrate dynamics: adaptation and trade-offs

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Eleni Vasilakou ◽  
Mark C. M. van Loosdrecht ◽  
S. Aljoscha Wahl
Keyword(s):  
Escherichia Coli ◽  
Short Term ◽  
Trade Offs

Effects of strategic tillage on short-term erosion, nutrient loss in runoff and greenhouse gas emissions

Soil Research ◽  
2017 ◽  
Vol 55 (3) ◽  
pp. 201 ◽  
Author(s):  
A. R. Melland ◽  
D. L. Antille ◽  
Y. P. Dang
Keyword(s):  
Nitrous Oxide ◽  
Greenhouse Gas ◽  
Heavy Rainfall ◽  
Ghg Emissions ◽  
Nutrient Loss ◽  
Nitrous Oxide Emissions ◽  
Nutrient Losses ◽  
Short Term ◽  
Trade Offs ◽  
Carbon Dioxide Co2

Occasional strategic tillage (ST) of long-term no-tillage (NT) soil to help control weeds may increase the risk of water, erosion and nutrient losses in runoff and of greenhouse gas (GHG) emissions compared with NT soil. The present study examined the short-term effect of ST on runoff and GHG emissions in NT soils under controlled-traffic farming regimes. A rainfall simulator was used to generate runoff from heavy rainfall (70mmh–1) on small plots of NT and ST on a Vertosol, Dermosol and Sodosol. Nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) fluxes from the Vertosol and Sodosol were measured before and after the rain using passive chambers. On the Sodosol and Dermosol there was 30% and 70% more runoff, respectively, from ST plots than from NT plots, however, volumes were similar between tillage treatments on the Vertosol. Erosion was highest after ST on the Sodosol (8.3tha–1 suspended sediment) and there were no treatment differences on the other soils. Total nitrogen (N) loads in runoff followed a similar pattern, with 10.2kgha–1 in runoff from the ST treatment on the Sodosol. Total phosphorus loads were higher after ST than NT on both the Sodosol (3.1 and 0.9kgha–1, respectively) and the Dermosol (1.0 and 0.3kgha–1, respectively). Dissolved nutrient forms comprised less than 13% of total losses. Nitrous oxide emissions were low from both NT and ST in these low-input systems. However, ST decreased CH4 absorption from both soils and almost doubled CO2 emissions from the Sodosol. Strategic tillage may increase the susceptibility of Sodosols and Dermosols to water, sediment and nutrient losses in runoff after heavy rainfall. The trade-offs between weed control, erosion and GHG emissions should be considered as part of any tillage strategy.

scholarly journals Breaking through evolutionary constraint by environmental fluctuations

2015 ◽  
Author(s):  
Marjon GJ de Vos ◽  
Alexandre Dawid ◽  
Vanda Sunderlikova ◽  
Sander J Tans
Keyword(s):  
Escherichia Coli ◽  
Environmental Variability ◽  
Model System ◽  
Evolutionary Constraint ◽  
Apparent Paradox ◽  
Epistatic Interactions ◽  
Genetic Constraints ◽  
Trade Offs ◽  
Fluctuating Environments ◽  
Genetic Constraint

Epistatic interactions can frustrate and shape evolutionary change. Indeed, phenotypes may fail to evolve because essential mutations can only be selected positively if fixed simultaneously. How environmental variability affects such constraints is poorly understood. Here we studied genetic constraints in fixed and fluctuating environments, using theEscherichia coli lacoperon as a model system for genotype-environment interactions. The data indicated an apparent paradox: in different fixed environments, mutational trajectories became trapped at sub-optima where no further improvements were possible, while repeated switching between these same environments allowed unconstrained adaptation by continuous improvements. Pervasive cross-environmental trade-offs transformed peaks into valleys upon environmental change, thus enabling escape from entrapment. This study shows that environmental variability can lift genetic constraint, and that trade-offs not only impede but can also facilitate adaptive evolution.

scholarly journals Escherichia colipopulations adapt to complex, unpredictable fluctuations without any trade-offs across environments

2016 ◽  
Author(s):  
Shraddha Karve ◽  
Devika Bhave ◽  
Dhanashri Nevgi ◽  
Sutirth Dey
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Growth Rates ◽  
Complex Environments ◽  
Multiple Stresses ◽  
Trade Off ◽  
Trade Offs ◽  
Fluctuating Environments ◽  
Laboratory Populations ◽  
Lower Variation

AbstractIn nature, organisms are simultaneously exposed to multiple stresses (i.e. complex environments) that often fluctuate unpredictably. While both these factors have been studied in isolation, the interaction of the two remains poorly explored. To address this issue, we selected laboratory populations ofEscherichia coliunder complex (i.e. stressful combinations of pH, H2O2and NaCl) unpredictably fluctuating environments for ~900 generations. We compared the growth rates and the corresponding trade-off patterns of these populations to those that were selected under constant values of the component stresses (i.e. pH, H2O2and NaCl) for the same duration. The fluctuation-selected populations had greater mean growth rate and lower variation for growth rate over all the selection environments experienced. However, while the populations selected under constant stresses experienced severe tradeoffs in many of the environments other than those in which they were selected, the fluctuation-selected populations could by-pass the across-environment trade-offs completely. Interestingly, trade-offs were found between growth rates and carrying capacities. The results suggest that complexity and fluctuations can strongly affect the underlying trade-off structure in evolving populations.

scholarly journals Primordial mimicry induces morphological change in Escherichia coli

2022 ◽  
Vol 5 (1) ◽  
Author(s):  
Hui Lu ◽  
Honoka Aida ◽  
Masaomi Kurokawa ◽  
Feng Chen ◽  
Yang Xia ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Fatty Acid ◽  
Morphological Change ◽  
Energy Resource ◽  
Volume Ratio ◽  
Living Cells ◽  
Carbon Utilization ◽  
Spherical Form ◽  
Trade Offs ◽  
Prebiotic Earth

AbstractThe morphology of primitive cells has been the subject of extensive research. A spherical form was commonly presumed in prebiotic studies but lacked experimental evidence in living cells. Whether and how the shape of living cells changed are unclear. Here we exposed the rod-shaped bacterium Escherichia coli to a resource utilization regime mimicking a primordial environment. Oleate was given as an easy-to-use model prebiotic nutrient, as fatty acid vesicles were likely present on the prebiotic Earth and might have been used as an energy resource. Six evolutionary lineages were generated under glucose-free but oleic acid vesicle (OAV)-rich conditions. Intriguingly, fitness increase was commonly associated with the morphological change from rod to sphere and the decreases in both the size and the area-to-volume ratio of the cell. The changed cell shape was conserved in either OAVs or glucose, regardless of the trade-offs in carbon utilization and protein abundance. Highly differentiated mutations present in the genome revealed two distinct strategies of adaption to OAV-rich conditions, i.e., either directly targeting the cell wall or not. The change in cell morphology of Escherichia coli for adapting to fatty acid availability supports the assumption of the primitive spherical form.

scholarly journals A study of the genotoxic potential of flavonoids using short-term bacterial assays.

1993 ◽  
Vol 40 (4) ◽  
pp. 549-554 ◽  
Author(s):  
H Czeczot ◽  
J Kusztelak
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Mutagenic Effect ◽  
Short Term ◽  
Sos System ◽  
Genotoxic Potential ◽  
Sos Chromotest ◽  
Activation System ◽  
K 12 ◽  
Alkylate Dna

Genotoxic activities of flavonoids (quercetin, rhamnetin, isorhamnetin, apigenin, luteolin) were investigated using two short-term bacterial assays. In the "repair test" in Salmonella typhimurium (strains TA1538 uvrB- and TA1978 uvrB+) the flavonoids studied did not introduce any damage into the DNA recognized by UvrABC nuclease (correndonuclease II). The results of the SOS-Chromotest in Escherichia coli K-12 strains PQ37 (tag+, alk+) and PQ243 (tagA, alkA) indicated that flavonoids only weakly induced the SOS system. The addition of a liver activation system (S9 mix) did not increase the mutagenic effect of the flavonoids tested. Two compounds: rhamnetin, isorhamnetin and their putative metabolites formed in the presence of the S9 mix did not alkylate DNA at N-3 of adenine.

Trajectories of Social Innovation

2019 ◽  
pp. 175-207
Author(s):  
György Molnár ◽  
Attila Havas
Keyword(s):  
Social Innovation ◽  
Complex Interventions ◽  
Complex Nature ◽  
Short Term ◽  
Cognitive Frames ◽  
Trade Offs ◽  
Capability Building ◽  
Major Factors ◽  
Socially Excluded ◽  
Practical Implications

The chapter analyses the specific features of social innovation for marginalized (SIM) or even socially excluded people, using the example of a social microcredit programme. It offers a review of the marginalization of the Roma in Hungary, considering the major factors of becoming marginalized as well as the processes reproducing marginalization, stressing the impacts of interactions between institutions, networks, and cognitive frames, showing that the complex nature of the reproduction of marginalization requires complex interventions, including empowering and capability building. The chapter highlights several policy and practical implications, including trade-offs to be considered when planning and implementing SIMs—in particular, those between exact targeting in a SIM versus building inter-community connections; the degree of assistance provided versus the short-term empowerment effect; and the degree of marginalization of the participants versus the costs of a given SIM.

Metabolic control analysis of L-tryptophan production with Escherichia coli based on data from short-term perturbation experiments

2020 ◽  
Vol 307 ◽  
pp. 15-28 ◽  
Author(s):  
Julia Tröndle ◽  
Kristin Schoppel ◽  
Arne Bleidt ◽  
Natalia Trachtmann ◽  
Georg A. Sprenger ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Metabolic Control ◽  
Metabolic Control Analysis ◽  
Control Analysis ◽  
Short Term

Economic Principles for Medicare Reform

2019 ◽  
Vol 686 (1) ◽  
pp. 63-92
Author(s):  
Amitabh Chandra ◽  
Craig Garthwaite
Keyword(s):  
Pay For Performance ◽  
Medicare Advantage ◽  
Short Term ◽  
Market Prices ◽  
Economic Framework ◽  
Trade Offs ◽  
Medicare Program ◽  
Commercial Market ◽  
New Treatments ◽  
Do So

In this article, we develop an economic framework for Medicare reform that highlights trade-offs that reform proposals should grapple with, but often ignore. Central to our argument is a tension in administratively set prices, which may improve short-term efficiency but do so at the expense of dynamic efficiency (slowing innovations in new treatments). The smaller the Medicare program is relative to the commercial market, the less important this is; but in a world where there are no market prices or the private sector is very small, the task of setting prices that are dynamically correct becomes more complex. Reforming Medicare should focus on greater incentives to increase competition between Medicare Advantage plans, which necessitates a role for government in ensuring competition; premium support; less use of regulated prices; and less appetite for countless “pay for performance” schemes. We apply this framework to evaluate Medicare for All proposals.

Sign in / Sign up

Export Citation Format

Share Document