Density-Dependent Individual and Population-Level Metabolic Rates in a Suite of Single-Celled Eukaryotes

DeLong, John P.; Hanson, David T.

doi:10.2174/1874196700902010032

Cited by 15 publications

(17 citation statements)

References 19 publications

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“…Our results show that the metabolic rate of individual T. pyriformis is suppressed with increasing density, and this suppression is linked to reduced birth rates and elevated death rates. The first link that density suppresses B pc through its effect on resource availability, is well supported by this study as well as our earlier experimental work (DeLong and Hanson, 2009). That suppression operated across a wide range of densities, not just near carrying capacity.…”

Section: Discussionsupporting

confidence: 86%

“…First, many experimental populations show sigmoidal growth, which implies densitydependent PGR (for example, Gause, 1934). Second, individual metabolic rates of protists are highly plastic and are negatively related to density (for example, Pace and Kimura, 1944;Nässberger andMonti, 1984, DeLong andHanson, 2009). Third, axenic cultures can be grown and the population change, total population metabolic rate and demographic parameters can be monitored simultaneously.…”

Section: Introductionmentioning

confidence: 99%

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Metabolic rate links density to demography in Tetrahymena pyriformis

DeLong

Hanson

2009

The ISME Journal

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Many populations show density-dependent growth rates. We suggest that population growth rate may be connected to density through the density dependence of metabolic rate. If metabolic rate is an index of the total biochemical work being done by an organism, then as populations grow and density suppresses metabolic rate, the rate of reproduction should slow and the ability to avoid death should diminish. To test this idea, we grew axenic populations of a single-celled protist, Tetrahymena pyriformis, in laboratory microcosms, and measured metabolic rate and density. We also estimated division (birth) and death rates. The proposed connection was supported by two observations. First, increasing population density suppressed per-capita metabolic rate in accordance with the predictions of a resource-division model. The same pattern was shown with experimentally altered densities. Second, per-capita metabolic rate was positively related to percapita division rate and negatively related to per-capita death rate. Thus, the particular pattern of population growth and regulation depends on exactly how individuals respond energetically to the density of conspecifics, and how they allocate metabolism to maintenance and production. The physiological basis of population regulation in this system is based on the constraints imposed on the total metabolic work that individual cells can perform.

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Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Metabolic rate links density to demography in Tetrahymena pyriformis

DeLong

Hanson

2009

The ISME Journal

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“…Here we found a negative effect of population density on per‐capita rates of photosynthesis and respiration. This finding is in agreement with several other studies showing a reduction in metabolic rate in response to increasing population density for both autotrophic and heterotrophic species (phytoplankton: DeLong and Hanson , b, other invertebrates: DeLong , Ghedini et al. in press, fish: Nadler et al.…”

Section: Discussionsupporting

confidence: 93%

Phytoplankton size‐scaling of net‐energy flux across light and biomass gradients

Malerba

White

Marshall

2017

Ecology

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Many studies examine how body size mediates energy use, but few investigate how size simultaneously regulates energy acquisition. Furthermore, rarely energy fluxes are examined while accounting for the role of biotic and abiotic factors in which they are nested. These limitations contribute to an incomplete understanding of how size affects the transfer of energy through individuals, populations, and communities. Here we characterized photosynthesis-irradiance (P-I) curves and per-cell net-energy use for 21 phytoplankton species spanning across four orders of magnitude of size and seven phyla, each measured across six light intensities and four population densities. We then used phylogenetic mixed models to quantify how body size influences the energy turnover rates of a species, and how this changes across environments. Rate-parameters for the P-I curve and net-energy budgets were mostly highly correlated and consistent with an allometric size-scaling exponent of <1. The energy flux of a cell decreased with population density and increased with light intensity, but the effect of body size remained constant across all combinations of treatment levels (i.e. no size×populationdensity interaction). The negative effect of population density on photosynthesis and respiration is mostly consistent with an active downregulation of metabolic rates following a decrease in per-cell resource availability, possibly as an adaptive strategy to reduce the minimum requirements of a cell and improve its competitive ability. Also, because an increase in body size corresponds to a less-than-proportional increase in net-energy (i.e. exponent<1), we propose that volume-specific net-energy flux can represent an important cost of evolving larger body sizes in autotrophic single-cell organisms.

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“…It is worth noting that the algal cell size was correlated with nutrient, light or temperature, especially the xenobiotics impact [50][51][52] . It suggests that the removal efficiency could be improved further just by the artificial controlled conditions rather than the chemical enhanced process such as Fenton oxidation or O 3 .…”

Section: Discussionmentioning

confidence: 99%

Enhancement by the artificial controlled culture for the algal treatment of antibiotic ceftazidime: a three-step response performance and high-removal efficiency

Feng

Guo

et al. 2015

RSC Adv.

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The improved activity of the alga is critical in the biological enhanced treatment to remove contamination. Organisms usually perform compensatory response resulting from an unfavorable condition. This work investigated the effect of the artificial controlled culture before the treatment, which provoked the possible algal compensatory response and helped the algae to perform a better removal capability on the antibiotic ceftazidime in the subsequent treatment process. The removal efficiency could be improved up to 99.15% in 6 h when the algae was under the artificial controlled light conditions before the treatment process. Additionally, higher removal efficiency (98.57% and 99.98%) was obtained after the artificial control on N and P, respectively. It suggests that the algae displayed a sequence of response during the exposure to the antibiotic after the artificial controlled culture in three steps: compensatory response, adsorption-consumption acceleration and acclimation. It might be the first time that the artificial conditions changing were controlled to improve the removal efficiency. Our work pointed out a new method for biological enhancement technologies in the antibiotic wastewater treatment. 6 investment holding group CO., LTD. Methanol and acetonitrile were HPLC grade.Other chemicals and reagents were analytical grade. Algal culturesThe green algae C. pyrenoidosa (FACHB-1220) which purchased from the Wuhan Hydrobiology Institute of Chinese Academy of Sciences, was pre-cultured in BG-11 media at 25 ± 1 • C and 4000 lux illumination (40 µmol photons m -2 s -1 ) with a light: dark interval of 12 h: 12 h. The algae was cultured for normally to reach the logarithmic growth phase in 3 d and prepared for the subsequent experiments. The experiment had three replications per treatment. Ceftazidime analysisCeftazidime was analyzed using a high-performance liquid chromatography (LC-10A, Shimadzu) apparatus coupled with UV detector. Stock solutions (1 g/L) of ceftazidime were dissolved in BG-11 media. The working solutions (40 mg/L) used in the treatment were then diluted from stock solutions. Antibiotic samples were separated and determined with an Inertsil ODS column (4.6 mm × 150 mm, 5 µm).The mobile phase of ceftazidime was acetonitrile-pH 3.9 phosphate buffer (volume ratio was 7:93). The flow rate was 1.0 mL/min with 20 ± 1.0 • C. The wavelength of the UV detector was 255 nm. Quantitation was performed using external standards and was based on peak areas. Experimental set-upIn the preliminary experiment, the removal rates of the target antibiotic tceftazidime by a dead and living algal cells were evaluated. We also evaluated the concentration

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Density-Dependent Individual and Population-Level Metabolic Rates in a Suite of Single-Celled Eukaryotes

Cited by 15 publications

References 19 publications

Metabolic rate links density to demography in Tetrahymena pyriformis

Metabolic rate links density to demography in Tetrahymena pyriformis

Phytoplankton size‐scaling of net‐energy flux across light and biomass gradients

Enhancement by the artificial controlled culture for the algal treatment of antibiotic ceftazidime: a three-step response performance and high-removal efficiency

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