The Thiamine Content of Phytoplankton Cells Is Affected by Abiotic Stress and Growth Rate

2012 ◽  
Vol 65 (3) ◽  
pp. 566-577 ◽  
Author(s):  
Peter Sylvander ◽  
Norbert Häubner ◽  
Pauline Snoeijs
Keyword(s):  
Growth Rate ◽  
Abiotic Stress ◽  
Thiamine Content ◽  
Phytoplankton Cells

scholarly journals Phytoplankton growth rate modelling: can spectroscopic cell chemotyping be superior to physiological predictors?

2017 ◽  
Vol 284 (1848) ◽  
pp. 20161956 ◽  
Author(s):  
Andrea Fanesi ◽  
Heiko Wagner ◽  
Christian Wilhelm
Keyword(s):  
Growth Rate ◽  
Predictive Power ◽  
Partial Least Square ◽  
Phytoplankton Growth ◽  
Photosynthetic Parameters ◽  
Strong Impact ◽  
High Predictive Power ◽  
Phytoplankton Communities ◽  
Quality Control Tool ◽  
Phytoplankton Cells

Climate change has a strong impact on phytoplankton communities and water quality. However, the development of robust techniques to assess phytoplankton growth is still in progress. In this study, the growth rate of phytoplankton cells grown at different temperatures was modelled based on conventional physiological traits (e.g. chlorophyll, carbon and photosynthetic parameters) using the partial least square regression (PLSR) algorithm and compared with a new approach combining Fourier transform infrared-spectroscopy and PLSR. In this second model, it is assumed that the macromolecular composition of phytoplankton cells represents an intracellular marker for growth. The models have comparable high predictive power ( R 2 > 0.8) and low error in predicting new observations. Interestingly, not all of the predictors present the same weight in the modelling of growth rate. A set of specific parameters, such as non-photochemical fluorescence quenching (NPQ) and the quantum yield of carbon production in the first model, and lipid, protein and carbohydrate contents for the second one, strongly covary with cell growth rate regardless of the taxonomic position of the phytoplankton species investigated. This reflects a set of specific physiological adjustments covarying with growth rate, conserved among taxonomically distant algal species that might be used as guidelines for the improvement of modern primary production models. The high predictive power of both sets of cellular traits for growth rate is of great importance for applied phycological studies. Our approach may find application as a quality control tool for the monitoring of phytoplankton populations in natural communities or in photobioreactors.

scholarly journals Terminal investment induced by a bacteriophage in a rhizosphere bacterium

F1000Research ◽  
2012 ◽  
Vol 1 ◽  
pp. 21 ◽  
Author(s):  
Timothée Poisot ◽  
Thomas Bell ◽  
Esteban Martinez ◽  
Claire Gougat-Barbera ◽  
Michael E Hochberg
Keyword(s):  
Growth Rate ◽  
Abiotic Stress ◽  
Stress Responses ◽  
Bacterial Cell ◽  
Population Growth Rate ◽  
Terminal Investment ◽  
Rhizosphere Bacterium ◽  
Interacting Populations ◽  
Microbial Responses ◽  
Microbial Model

Despite knowledge about microbial responses to abiotic stress, few studies have investigated stress responses to antagonistic species, such as competitors, predators and pathogens. While it is often assumed that interacting populations of bacteria and phage will coevolve resistance and exploitation strategies, an alternative is that individual bacteria tolerate or evade phage predation through inducible responses to phage presence. Using the microbial modelPseudomonas fluorescensSBW25 and its lytic DNA phage SBW25Φ2, we demonstrate the existence of an inducible response in the form of a transient increase in population growth rate, and found that the response was induced by phage binding. This response was accompanied by a decrease in bacterial cell size, which we propose to be an associated cost. We discuss these results in the context of bacterial ecology and phage-bacteria co-evolution.

scholarly journals Adaptive diversification of growth allometry in the plant Arabidopsis thaliana

2018 ◽  
Author(s):  
François Vasseur ◽  
Moises Exposito-Alonso ◽  
Oscar Ayala-Garay ◽  
George Wang ◽  
Brian J. Enquist ◽  
...  
Keyword(s):  
Growth Rate ◽  
Arabidopsis Thaliana ◽  
Abiotic Stress ◽  
Seed Production ◽  
Allometric Scaling ◽  
Abiotic Stress Response ◽  
Scaling Exponents ◽  
Metabolic Scaling ◽  
Metabolic Scaling Theory ◽  
Growth Scaling

AbstractSeed plants vary tremendously in size and morphology. However, variation and covariation between plant traits may at least in part be governed by universal biophysical laws and biological constants. Metabolic Scaling Theory (MST) posits that whole-organismal metabolism and growth rate are under stabilizing selection that minimizes the scaling of hydrodynamic resistance and maximizes the scaling of resource uptake. This constrains variation in physiological traits and in the rate of biomass accumulation, so that they can be expressed as mathematical functions of plant size with near constant allometric scaling exponents across species. However, observed variation in scaling exponents questions the evolutionary drivers and the universality of allometric equations. We have measured growth scaling and fitness traits of 451 Arabidopsis thaliana accessions with sequenced genomes. Variation among accessions around the scaling exponent predicted by MST correlated with relative growth rate, seed production and stress resistance. Genomic analyses indicate that growth allometry is affected by many genes associated with local climate and abiotic stress response. The gene with the strongest effect, PUB4, has molecular signatures of balancing selection, suggesting that intraspecific variation in growth scaling is maintained by opposing selection on the trade-off between seed production and abiotic stress resistance. Our findings support a core MST prediction and suggest that variation in allometry contributes to local adaptation to contrasting environments. Our results help reconcile past debates on the origin of allometric scaling in biology, and begin to link adaptive variation in allometric scaling to specific genes.Significance statementAre there biological constants unifying phenotypic diversity across scales? Metabolic Scaling Theory (MST) predicts mathematical regularity and constancy in the allometric scaling of growth rate with body size across species. Here, we show that adaptation to climate in Arabidopsis thaliana is associated with local strains that substantially deviate from the values predicted by MST. This deviation can be linked to increased stress tolerance at the expense of seed production, and it occurs through selection on genes that are involved in abiotic stress response and that are geographically correlated with climatic conditions. This highlights the evolutionary role of allometric diversification and helps establish the physiological bases of plant adaptation to contrasting environments.

scholarly journals Adaptive diversification of growth allometry in the plant Arabidopsis thaliana

2018 ◽  
Vol 115 (13) ◽  
pp. 3416-3421 ◽  
Author(s):  
François Vasseur ◽  
Moises Exposito-Alonso ◽  
Oscar J. Ayala-Garay ◽  
George Wang ◽  
Brian J. Enquist ◽  
...  
Keyword(s):  
Growth Rate ◽  
Arabidopsis Thaliana ◽  
Abiotic Stress ◽  
Seed Production ◽  
Stress Resistance ◽  
Allometric Scaling ◽  
Hydrodynamic Resistance ◽  
Scaling Exponent ◽  
Scaling Exponents ◽  
Growth Scaling

Seed plants vary tremendously in size and morphology; however, variation and covariation in plant traits may be governed, at least in part, by universal biophysical laws and biological constants. Metabolic scaling theory (MST) posits that whole-organismal metabolism and growth rate are under stabilizing selection that minimizes the scaling of hydrodynamic resistance and maximizes the scaling of resource uptake. This constrains variation in physiological traits and in the rate of biomass accumulation, so that they can be expressed as mathematical functions of plant size with near-constant allometric scaling exponents across species. However, the observed variation in scaling exponents calls into question the evolutionary drivers and the universality of allometric equations. We have measured growth scaling and fitness traits of 451 Arabidopsis thaliana accessions with sequenced genomes. Variation among accessions around the scaling exponent predicted by MST was correlated with relative growth rate, seed production, and stress resistance. Genomic analyses indicate that growth allometry is affected by many genes associated with local climate and abiotic stress response. The gene with the strongest effect, PUB4, has molecular signatures of balancing selection, suggesting that intraspecific variation in growth scaling is maintained by opposing selection on the trade-off between seed production and abiotic stress resistance. Our findings suggest that variation in allometry contributes to local adaptation to contrasting environments. Our results help reconcile past debates on the origin of allometric scaling in biology and begin to link adaptive variation in allometric scaling to specific genes.

scholarly journals Terminal investment induced by a bacteriophage in a rhizosphere bacterium

F1000Research ◽  
2013 ◽  
Vol 1 ◽  
pp. 21 ◽  
Author(s):  
Timothée Poisot ◽  
Thomas Bell ◽  
Esteban Martinez ◽  
Claire Gougat-Barbera ◽  
Michael E Hochberg
Keyword(s):  
Growth Rate ◽  
Abiotic Stress ◽  
Stress Responses ◽  
Bacterial Cell ◽  
Population Growth Rate ◽  
Terminal Investment ◽  
Rhizosphere Bacterium ◽  
Interacting Populations ◽  
Microbial Responses ◽  
Microbial Model

Despite knowledge about microbial responses to abiotic stress, few studies have investigated stress responses to antagonistic species, such as competitors, predators and pathogens. While it is often assumed that interacting populations of bacteria and phage will coevolve resistance and exploitation strategies, an alternative is that individual bacteria tolerate or evade phage predation through inducible responses to phage presence. Using the microbial modelPseudomonas fluorescensSBW25 and its lytic DNA phage SBW25Φ2, we demonstrate the existence of an inducible response in the form of a transient increase in population growth rate, and found that the response was induced by phage binding. This response was accompanied by a decrease in bacterial cell size, which we propose to be an associated cost. We discuss these results in the context of bacterial ecology and phage-bacteria co-evolution.

The threshold energy for atom displacement in fcc metals

1990 ◽  
Vol 48 (4) ◽  
pp. 530-531
Author(s):  
Wilfried Sigle ◽  
Matthias Hohenstein ◽  
Alfred Seeger
Keyword(s):  
Growth Rate ◽  
Elevated Temperatures ◽  
Threshold Energy ◽  
Dislocation Loops ◽  
Absolute Minimum ◽  
Voltage Electron ◽  
Atom Displacement ◽  
Electron Microscopes ◽  
Fcc Metal

Prolonged electron irradiation of metals at elevated temperatures usually leads to the formation of large interstitial-type dislocation loops. The growth rate of the loops is proportional to the total cross-section for atom displacement,which is implicitly connected with the threshold energy for atom displacement, Ed . Thus, by measuring the growth rate as a function of the electron energy and the orientation of the specimen with respect to the electron beam, the anisotropy of Ed can be determined rather precisely. We have performed such experiments in situ in high-voltage electron microscopes on Ag and Au at 473K as a function of the orientation and on Au as a function of temperature at several fixed orientations.Whereas in Ag minima of Ed are found close to <100>,<110>, and <210> (13-18eV), (Fig.1) atom displacement in Au requires least energy along <100>(15-19eV) (Fig.2). Au is thus the first fcc metal in which the absolute minimum of the threshold energy has been established not to lie in or close to the <110> direction.

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