scholarly journals Empirical Leucine-to-Carbon Conversion Factors for Estimating Heterotrophic Bacterial Production: Seasonality and Predictability in a Temperate Coastal Ecosystem

2009 ◽  
Vol 75 (10) ◽  
pp. 3216-3221 ◽  
Author(s):  
Alejandra Calvo-D�az ◽  
Xos� Anxelu G. Mor�n
Keyword(s):  
Protein Synthesis ◽  
Bacterial Production ◽  
Heterotrophic Bacteria ◽  
Spatiotemporal Variability ◽  
Leucine Incorporation ◽  
Carbon Conversion ◽  
Conversion Factors ◽  
Production Studies ◽  
Favorable Conditions

ABSTRACT Leucine-to-carbon conversion factors (CFs) are needed for converting substrate incorporation into biomass production of heterotrophic bacteria. During 2006 we performed 20 dilution experiments for determining the spatiotemporal variability of empirical CFs in temperate Atlantic coastal waters. Values (0.49 to 1.92 kg C mol Leu−1) showed maxima in autumn to early winter and minima in summer. Spatially averaged CFs were significantly negatively correlated with in situ leucine incorporation rates (r = −0.91) and positively correlated with phosphate concentrations (r = 0.76). These relationships, together with a strong positive covariation between cell-specific leucine incorporation rates and carbon contents (r = 0.85), were interpreted as a strategy to maximize survival through protein synthesis and low growth rates under nutrient limitation (low CFs) until favorable conditions stimulate cell division relative to protein synthesis (high CFs). A multiple regression with in situ leucine incorporation rates and cellular carbon contents explained 96% of CF variance in our ecosystem, suggesting their potential prediction from more easily measurable routine variables. The use of the theoretical CF of 1.55 kg C mol Leu−1 would have resulted in a serious overestimation (73%) of annual bacterial production rates. Our results emphasize the need for considering the temporal scale in CFs for bacterial production studies.

scholarly journals Empirical leucine-to-carbon conversion factors in north-eastern Atlantic waters (50–2000 m) shaped by bacterial community composition and optical signature of DOM

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. Pamela Orta-Ponce ◽  
Tamara Rodríguez-Ramos ◽  
Mar Nieto-Cid ◽  
Eva Teira ◽  
Elisa Guerrero-Feijóo ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
North Atlantic Ocean ◽  
Bacterial Community Composition ◽  
Multiple Linear Regression Model ◽  
Carbon Conversion ◽  
Phylogenetic Groups ◽  
Conversion Factors ◽  
The North ◽  
Microbial Utilization ◽  
Optical Signature

AbstractMicrobial heterotrophic activity is a major process regulating the flux of dissolved organic matter (DOM) in the ocean, while the characteristics of this DOM strongly influence its microbial utilization and fate in the ocean. In order to broaden the vertical resolution of leucine-to-carbon conversion factors (CFs), needed for converting substrate incorporation into biomass production by heterotrophic bacteria, 20 dilution experiments were performed in the North Atlantic Ocean. We found a depth-stratification in empirical CFs values from epipelagic to bathypelagic waters (4.00 ± 1.09 to 0.10 ± 0.00 kg C mol Leu−1). Our results demonstrated that the customarily used theoretical CF of 1.55 kg C mol Leu−1 in oceanic samples can lead to an underestimation of prokaryotic heterotrophic production in epi- and mesopelagic waters, while it can overestimate it in the bathypelagic ocean. Pearson correlations showed that CFs were related not only to hydrographic variables such as temperature, but also to specific phylogenetic groups and DOM quality and quantity indices. Furthermore, a multiple linear regression model predicting CFs from relatively simple hydrographic and optical spectroscopic measurements was attempted. Taken together, our results suggest that differences in CFs throughout the water column are significantly connected to DOM, and also reflect differences linked to specific prokaryotic groups.

[methyl-3H]Thymidine and [3H]leucine incorporation in Vibrio spp. grown in nutrient-limited continuous cultures

1994 ◽  
Vol 40 (5) ◽  
pp. 375-381 ◽  
Author(s):  
Richard A. Snyder ◽  
Richard D. Robarts ◽  
Douglas E. Caldwell
Keyword(s):  
Cell Volume ◽  
Bacterial Production ◽  
Conversion Factor ◽  
De Novo ◽  
Leucine Incorporation ◽  
Continuous Cultures ◽  
Average Cell ◽  
Conversion Factors ◽  
Significant Difference ◽  
Number Of Bacteria

Vibrio alginolyticus, Vibrio logei, Vibrio natriegens, and Vibrio neries were grown in nutrient-limited continuous cultures at generation times (TD) of 5–135 h on complex media with cell yields of 0.8–12 × 106 bacteria/mL. Average cell volume, as determined by image analysis of video fluorescence microscopy, decreased for V. logei and V. neries, did not change for V. alginolyticus, and increased for V. natriegens with increasing TD. The increase in cell volume observed for V. natriegens was due to the development of filamentous cells. Batch cultures were grown on media with 10 times the nutrient concentration of continuous cultures. Tritiated thymidine incorporation was measured using phenol–chloroform extractions; leucine incorporation was measured in trichloroacetic acid precipitates. At concentrations of exogenous thymidine high enough to inhibit de novo synthesis of thymidine, the number of bacteria produced per mole of thymidine incorporated did not vary with changing generation time, or between batch and continuous cultures examined in this study. However, the number of bacteria produced per mole of leucine incorporated decreased per unit production with increasing TD for all four vibrios. A significant difference in the bacterial production conversion factor (bacteria produced per mole of label incorporated) for thymidine was found for V. neries relative to the three other Vibrio species, but no significant differences were found between growth conditions within species. Corrections for biovolume differences between species and growth rates reduced variability in conversion factors, and also yielded a significantly different conversion factor for V. neries. Conversion factors for leucine incorporation spanned three orders of magnitude, from 1015 to 1018 bacteria/mol of leucine incorporated.Key words: leucine, thymidine, bacterial production, chemostats.

Macro and micro nutrient limitation of microbial productivity in oligotrophic subtropical Atlantic waters

2008 ◽  
Vol 5 (2) ◽  
pp. 135 ◽  
Author(s):  
Joanna L. Dixon
Keyword(s):  
Primary Production ◽  
Bacterial Production ◽  
Heterotrophic Bacteria ◽  
Total Carbon ◽  
North East ◽  
Incubation Experiments ◽  
Subtropical Oceans ◽  
Marine Primary Production

Environmental context. The subtropical oceans comprise ~70% of the world’s ocean surface and profoundly affect global biogeochemistry and climate. They are characteristically low-nutrient regions, but, owing to their large extent and often rapid nutrient turnover, may contribute to greater than 30% of the total marine primary production. However, there remains long-standing uncertainty as to what individual or combination of resources, e.g. macro (N, P) and micro (trace metals) nutrients, limit or co-limit marine productivity and thus total carbon fixation in these spatially dominant gyre systems. Abstract. The subtropical oceans are characteristically low-nutrient low-chlorophyll regions, but owing to their geographical dominance and rapid nutrient cycling may contribute >30% of the total marine primary production. The present study investigates the addition of P, Fe, Co and Zn on rates of primary production and heterotrophic bacterial production, through a combination of mesoscale in situ (P, and P + Fe) and in vitro (Co or Zn) bioassay incubation experiments. Results from the bioassay incubation experiments suggest that primary production and chlorophyll a biomass are limited by N and P in this oligotrophic region. However, both were increased further after addition of trace metal micronutrients in the order Fe + Zn ≥ Fe + Co > Fe ≈ Co. In contrast, rates of heterotrophic bacterial production did not appear to be P, or significantly, P + Fe limited, although in situ rates did increase during the first 12 h of mesoscale P fertilisation (which were not mirrored in the mesoscale P + Fe addition). The addition of Co to unfertilised waters increased heterotrophic bacterial production and the numbers of heterotrophic bacteria, Prochlorococcus spp. and Synechococcus spp., suggesting Co limitation. Prochlorococcus spp. were the most abundant autotrophs. The highest increases in both heterotrophic and autotrophic carbon assimilation were shown after in vitro addition of either Co or Zn to mesoscale enriched P + Fe waters, suggesting multiple limitation of microbial growth rates in the subtropical oligotrophic north-east Atlantic.

scholarly journals Factors limiting heterotrophic bacterial production in the southern Pacific Ocean

2008 ◽  
Vol 5 (3) ◽  
pp. 833-845 ◽  
Author(s):  
F. Van Wambeke ◽  
S. Bonnet ◽  
T. Moutin ◽  
P. Raimbault ◽  
G. Alarcón ◽  
...  
Keyword(s):  
Bacterial Production ◽  
Heterotrophic Bacteria ◽  
Leucine Incorporation ◽  
Limiting Factor ◽  
Labile Carbon ◽  
Longitudinal Gradients ◽  
Eastern Border ◽  
Potential Factors ◽  
Seawater Samples ◽  
Enrichment Experiments

Abstract. The role of potential factors limiting bacterial growth was investigated along vertical and longitudinal gradients across the South Eastern Pacific Gyre. The effects of glucose, nitrate, ammonium and phosphate additions on heterotrophic bacterial production (using leucine technique) were studied in parallel in unfiltered seawater samples incubated under natural daily irradiance. The enrichments realized on the subsurface showed three types of responses. From 141° W (Marquesas plateau) to approx 125° W, bacteria were not bottom-up controlled, as confirmed by the huge potential of growth in non-enriched seawater (median of enhancement factor×39 in 24 h). Within the Gyre (125° W–95° W), nitrogen alone stimulated leucine incorporation rates (median×4.2), but rapidly labile carbon (glucose) became a second limiting factor (median×37) when the two elements were added. Finally from the border of the gyre to the Chilean upwelling (95° W–73° W), labile carbon was the only factor stimulating heterotrophic bacterial production. Interaction between phytoplankton and heterotrophic bacterial communities and the direct versus indirect effect of iron and macronutrients on bacterial production were also investigated in four selected sites: two sites on the vicinity of the Marquesas plateau, the centre of the gyre and the Eastern border of the gyre. Both phytoplankton and heterotrophic bacteria were limited by availability of nitrogen within the gyre, but not by iron. Iron limited phytoplankton at Marquesas plateau and at the eastern border of the gyre. However 48 h enrichment experiments were not sufficient to show any clear limitation of heterotrophic bacteria within Marquesas plateau and showed a limitation of these organisms by labile carbon in the eastern border of the Gyre.

scholarly journals Factors limiting heterotrophic bacterial production in the southern Pacific Ocean

2007 ◽  
Vol 4 (5) ◽  
pp. 3799-3828 ◽  
Author(s):  
F. Van Wambeke ◽  
S. Bonnet ◽  
T. Moutin ◽  
P. Raimbault ◽  
G. Alarçon ◽  
...  
Keyword(s):  
Bacterial Production ◽  
Heterotrophic Bacteria ◽  
Leucine Incorporation ◽  
Limiting Factor ◽  
Labile Carbon ◽  
Longitudinal Gradients ◽  
Eastern Border ◽  
Potential Factors ◽  
Seawater Samples

Abstract. The role of potential factors limiting bacterial growth was investigated along vertical and longitudinal gradients across the South Eastern Pacific Gyre. The effects of glucose, nitrate, ammonium and phosphate additions on heterotrophic bacterial production (using leucine technique) were studied in parallel in unfiltered seawater samples incubated under natural daily irradiance. Longitudinally, the enrichments realized on the subsurface showed three types of responses. From the Marquesas plateau (8° W to approx 125° W), bacteria were not bottom-up controlled, as confirmed by the huge potential of growth in non-enriched seawater (43±24 times in 24 h). Within the Gyre (125° W–95° W), nitrogen alone stimulated leucine incorporation rates by a factor of 5.6±3.6, but rapidly labile carbon (glucose) became a second limiting factor (enhancement factor 49±32 when the two elements were added). Finally from the border of the gyre to the Chilean upwelling (95° W–73° W), labile carbon was the only factor stimulating heterotrophic bacterial production. Interaction between phytoplankton and heterotrophic bacterial communities and the direct versus indirect effect of iron and macronutrients on bacterial production were also investigated in four selected sites: two sites on the vicinity of the Marquesas plateau, the centre of the gyre and the Eastern border of the gyre. Both phytoplankton and heterotrophic bacteria were limited by availability of nitrogen within the gyre, but not by iron. While iron limited phytoplankton at Marquesas plateau and at the eastern border of the gyre, heterotrophic bacteria were only limited by availability of labile DOC in those environments.

Altered protein synthesis during in situ oat leaf senescence

1990 ◽  
Vol 80 (4) ◽  
pp. 619-623 ◽  
Author(s):  
Louise Lalonde ◽  
Rajinder S. Dhindsa
Keyword(s):  
Protein Synthesis ◽  
Leaf Senescence ◽  
Altered Protein

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

scholarly journals Cell-free protein synthesis and in situ immobilization of deGFP-MatB in polymer microgels for malonate-to-malonyl CoA conversion

RSC Advances ◽  
2020 ◽  
Vol 10 (66) ◽  
pp. 40588-40596
Author(s):  
Tony Köhler ◽  
Thomas Heida ◽  
Sandra Hoefgen ◽  
Niclas Weigel ◽  
Vito Valiante ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Genetic Information ◽  
In Situ Immobilization ◽  
Bottom Up ◽  
Free Protein ◽  
Malonyl Coa ◽  
Cell Free Protein Synthesis

We describe a bottom-up approach towards functional enzymes utilizing microgels as carriers for genetic information that enable cell-free protein synthesis, in situ immobilization, and utilization of functional deGFP-MatB.

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