Nutrient diffusing substrata: a field comparison of commonly used methods to assess nutrient limitation

2011 ◽  
Vol 30 (2) ◽  
pp. 522-532 ◽  
Author(s):  
Krista A. Capps ◽  
Michael T. Booth ◽  
Sarah M. Collins ◽  
Marita A. Davison ◽  
Jennifer M. Moslemi ◽  
...  
Keyword(s):  
Nutrient Limitation ◽  
Nutrient Diffusing Substrata

Salmon subsidies alleviate nutrient limitation of benthic biofilms in southeast Alaska streams

2011 ◽  
Vol 68 (2) ◽  
pp. 277-287 ◽  
Author(s):  
Janine Rüegg ◽  
Scott D. Tiegs ◽  
Dominic T. Chaloner ◽  
Peter S. Levi ◽  
Jennifer L. Tank ◽  
...  
Keyword(s):  
Nutrient Limitation ◽  
Fold Increase ◽  
N:P Ratio ◽  
Community Respiration ◽  
Ammonium Concentration ◽  
Resource Subsidies ◽  
Southeast Alaska ◽  
P Limitation ◽  
Autotrophic Biofilms ◽  
Nutrient Diffusing Substrata

Using nutrient-diffusing substrata (NDS) in seven streams in southeast Alaska, USA, we tested whether (i) nutrient limitation of autotrophic and heterotrophic biofilms was alleviated by salmon resource subsidies, and (ii) whether the degree of alleviation could be predicted by environmental variables. Before salmon spawners arrived, autotrophic biofilms were nitrogen (N)-limited, or co-limited by N and phosphorus (P), whereas heterotrophic biofilms were either P-limited, or co-limited by N and P. Combined N and P amendments resulted in a 2.6-fold increase in biofilm chlorophyll a, and a 3.2-fold increase in community respiration. After salmon arrived, autotroph nutrient limitation was alleviated in six of the seven streams. Heterotrophs still exhibited nutrient limitation in six streams, but most streams shifted from co-limitation to P-limitation. Nutrient-diffusing substrata amended with salmon tissue indicated that salmon could also be an important source of organic carbon for biofilms. Autotrophs responded less to N and P amendments as streamwater ammonium concentration increased with the arrival of salmon. For heterotrophs, ammonium concentration and N:P ratio best predicted changes in response following the arrival of salmon. We provide the first direct evidence that biofilm nutrient limitation can be alleviated by salmon spawners in nutrient-poor streams.

scholarly journals Metabolic response of Botryococcus braunii to high bicarbonate dosages and other conditions: analysis of photosynthetic performance, productivity, and lipidomic profile

2021 ◽  
Author(s):  
Néstor David Giraldo ◽  
Sandra Marcela Correa ◽  
Andrés Arbeláez ◽  
Felix L. Figueroa ◽  
Rigoberto Ríos-Estepa ◽  
...  
Keyword(s):  
Nutrient Limitation ◽  
Metabolic Response ◽  
Neutral Lipids ◽  
Biomass Productivity ◽  
Botryococcus Braunii ◽  
Photosynthetic Performance ◽  
Lipid Productivity ◽  
Cellular Growth ◽  
Adaptive Responses ◽  
Nitrogen And Phosphorus

AbstractIn this study the metabolic responses of Botryococcus braunii were analyzed upon different inorganic carbon dosages and nutrient limitation conditions in terms of lipid and biomass productivity, as well as photosynthetic performance. The nutritional schemes evaluated included different levels of sodium bicarbonate and nitrogen and phosphorus starvation, which were contrasted against standard cultures fed with CO2. Bicarbonate was found to be an advantageous carbon source since high dosages caused a significant increase in biomass and lipid productivity, in addition to an enhanced photosynthetic quantum yield and neutral lipids abundance. This contrasts to the commonly used approach of microalgae nutrient limitation, which leads to high lipid accumulation at the expense of impaired cellular growth, causing a decline in overall lipid productivity. The lipidome analysis served to hypothesize about the influence of the nutritional context on B. braunii structural and storage lipid metabolism, besides the adaptive responses exhibited by cells that underwent nutrient stress.

scholarly journals Kog1/Raptor mediates metabolic rewiring during nutrient limitation by controlling SNF1/AMPK activity

2021 ◽  
Vol 7 (16) ◽  
pp. eabe5544
Author(s):  
Zeenat Rashida ◽  
Rajalakshmi Srinivasan ◽  
Meghana Cyanam ◽  
Sunil Laxman
Keyword(s):  
Amino Acid ◽  
Nutrient Limitation ◽  
Carbon Flux ◽  
Metabolic Flux ◽  
Carbon Allocation ◽  
Carbon Utilization ◽  
Acid Biosynthesis ◽  
Control Growth ◽  
Ampk Activity ◽  
Delayed Growth

In changing environments, cells modulate resource budgeting through distinct metabolic routes to control growth. Accordingly, the TORC1 and SNF1/AMPK pathways operate contrastingly in nutrient replete or limited environments to maintain homeostasis. The functions of TORC1 under glucose and amino acid limitation are relatively unknown. We identified a modified form of the yeast TORC1 component Kog1/Raptor, which exhibits delayed growth exclusively during glucose and amino acid limitations. Using this, we found a necessary function for Kog1 in these conditions where TORC1 kinase activity is undetectable. Metabolic flux and transcriptome analysis revealed that Kog1 controls SNF1-dependent carbon flux apportioning between glutamate/amino acid biosynthesis and gluconeogenesis. Kog1 regulates SNF1/AMPK activity and outputs and mediates a rapamycin-independent activation of the SNF1 targets Mig1 and Cat8. This enables effective glucose derepression, gluconeogenesis activation, and carbon allocation through different pathways. Therefore, Kog1 centrally regulates metabolic homeostasis and carbon utilization during nutrient limitation by managing SNF1 activity.

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