Acclimation of unicellular cyanobacteria to macronutrient deficiency: emergence of a complex network of cellular responses

Microbiology ◽  
2005 ◽  
Vol 151 (8) ◽  
pp. 2503-2514 ◽  
Author(s):  
Rakefet Schwarz ◽  
Karl Forchhammer
Keyword(s):  
Nutrient Limitation ◽  
Complex Network ◽  
Nitrogen Limitation ◽  
Molecular Mechanisms ◽  
Photosynthetic Apparatus ◽  
Cellular Responses ◽  
Nitrogen And Phosphorus ◽  
Starvation Condition ◽  
Phosphorus Deprivation ◽  
Micro Organisms

Cyanobacteria are equipped with numerous mechanisms that allow them to survive under conditions of nutrient starvation, some of which are unique to these organisms. This review surveys the molecular mechanisms underlying acclimation responses to nitrogen and phosphorus deprivation, with an emphasis on non-diazotrophic freshwater cyanobacteria. As documented for other micro-organisms, nutrient limitation of cyanobacteria elicits both general and specific responses. The general responses occur under any starvation condition and are the result of the stresses imposed by arrested anabolism. In contrast, the specific responses are acclimation processes that occur as a result of limitation for a particular nutrient; they lead to modification of metabolic and physiological routes to compensate for the restriction. First, the general acclimation processes are discussed, with an emphasis on modifications of the photosynthetic apparatus. The molecular mechanisms underlying specific responses to phosphorus and nitrogen-limitation are then outlined, and finally the cross-talk between pathways modulating specific and general responses is described.

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 Ionizing Radiation and Translation Control: A Link to Radiation Hormesis?

2020 ◽  
Vol 21 (18) ◽  
pp. 6650
Author(s):  
Usha Kabilan ◽  
Tyson E. Graber ◽  
Tommy Alain ◽  
Dmitry Klokov
Keyword(s):  
Protein Synthesis ◽  
Ionizing Radiation ◽  
Molecular Mechanisms ◽  
Low Dose ◽  
Mrna Translation ◽  
Cellular Responses ◽  
Translation Control ◽  
Cis Acting ◽  
Radiation Hormesis ◽  
Downstream Signaling

Protein synthesis, or mRNA translation, is one of the most energy-consuming functions in cells. Translation of mRNA into proteins is thus highly regulated by and integrated with upstream and downstream signaling pathways, dependent on various transacting proteins and cis-acting elements within the substrate mRNAs. Under conditions of stress, such as exposure to ionizing radiation, regulatory mechanisms reprogram protein synthesis to translate mRNAs encoding proteins that ensure proper cellular responses. Interestingly, beneficial responses to low-dose radiation exposure, known as radiation hormesis, have been described in several models, but the molecular mechanisms behind this phenomenon are largely unknown. In this review, we explore how differences in cellular responses to high- vs. low-dose ionizing radiation are realized through the modulation of molecular pathways with a particular emphasis on the regulation of mRNA translation control.

scholarly journals Innate cellular responses to rotavirus infection

2013 ◽  
Vol 94 (6) ◽  
pp. 1151-1160 ◽  
Author(s):  
Gavan Holloway ◽  
Barbara S. Coulson
Keyword(s):  
Protective Immunity ◽  
Molecular Mechanisms ◽  
Cellular Responses ◽  
Innate Immune ◽  
Host Cells ◽  
Type I ◽  
First Line ◽  
Comprehensive Overview ◽  
Rotavirus Infection ◽  
Infants And Young Children

Rotavirus is a leading cause of severe dehydrating diarrhoea in infants and young children. Following rotavirus infection in the intestine an innate immune response is rapidly triggered. This response leads to the induction of type I and type III interferons (IFNs) and other cytokines, resulting in a reduction in viral replication. Here we review the current literature describing the detection of rotavirus infection by pattern recognition receptors within host cells, the subsequent molecular mechanisms leading to IFN and cytokine production, and the processes leading to reduced rotavirus replication and the development of protective immunity. Rotavirus countermeasures against innate responses, and their roles in modulating rotavirus replication in mice, also are discussed. By linking these different aspects of innate immunity, we provide a comprehensive overview of the host’s first line of defence against rotavirus infection. Understanding these processes is expected to be of benefit in improving strategies to combat rotavirus disease.

scholarly journals Evaluation of radical scavenging system in amoeba Chaos carolinense during nutrient deprivation

2017 ◽  
Vol 7 (4) ◽  
pp. 20160113 ◽  
Author(s):  
Yuru Deng ◽  
Edlyn Li-Hui Lee ◽  
Ketpin Chong ◽  
Zakaria A. Almsherqi
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
Nucleic Acids ◽  
Cellular Response ◽  
Molecular Mechanisms ◽  
Antioxidant Activities ◽  
Radical Scavenging ◽  
Cellular Responses ◽  
Biological Macromolecules

The frequent appearance of non-lamellar membrane arrangements such as cubic membranes (CMs) in cells under stressed or pathological conditions points to an intrinsic cellular response mechanism. CM represents highly curved, three-dimensional nano-periodic structures that correspond to mathematically well-defined triply periodic minimal surfaces. Specifically, cellular membrane may transform into CM organization in response to pathological, inflammatory and oxidative stress conditions. CM organization, thus, may provide an advantage to cope with various types of stress. The identification of inducible membrane systems, such as in the mitochondrial inner membranes to cubic morphology upon starvation, opens new avenues for understanding the molecular mechanisms of cellular responses to oxidative stress. In this study, we compared the cellular responses of starved and fed amoeba Chaos carolinense to oxidative stress. Food deprivation from C. carolinense induces a significant increase in prooxidants such as superoxide and hydrogen peroxide. Surprisingly, we observed a significant lower rate of biomolecular damage in starved cells (with higher free radicals generation) when compared with fed cells. Specifically, lipid and RNA damages were significantly less in starved cells compared with fed cells. This observation was not due to the upregulation of intracellular antioxidants, as starved amoeba show reduced antioxidant enzymatic activities; however, it could be attributed to CM formation. CM could uptake and retain short segments of nucleic acids (resembles cellular RNA) in vivo and in vitro. Previous results showed that nucleic acids retained within CM sustain a minimal oxidative damage in vitro upon exposure to high level of superoxide. We thus propose that CM may act as a ‘protective’ shelter to minimize the oxidation of biologically essential macromolecules such as RNA. In summary, we examined enzymatic antioxidant activities as well as oxidative damage biomarkers in starved amoeba C. carolinense in correlation with the potential role of CM as an optimal intracellular membrane organization for the protection of biological macromolecules against oxidative damage.

scholarly journals Cellular Responses to Proteasome Inhibition: Molecular Mechanisms and Beyond

2019 ◽  
Vol 20 (14) ◽  
pp. 3379 ◽  
Author(s):  
Nicolas Albornoz ◽  
Hianara Bustamante ◽  
Andrea Soza ◽  
Patricia Burgos
Keyword(s):  
Side Effects ◽  
Inclusion Bodies ◽  
Molecular Mechanisms ◽  
Proteasome Inhibitors ◽  
Proteasome Inhibition ◽  
Cellular Responses ◽  
Cell Responses ◽  
Different Types ◽  
Inflammatory Processes

Proteasome inhibitors have been actively tested as potential anticancer drugs and in the treatment of inflammatory and autoimmune diseases. Unfortunately, cells adapt to survive in the presence of proteasome inhibitors activating a variety of cell responses that explain why these therapies have not fulfilled their expected results. In addition, all proteasome inhibitors tested and approved by the FDA have caused a variety of side effects in humans. Here, we describe the different types of proteasome complexes found within cells and the variety of regulators proteins that can modulate their activities, including those that are upregulated in the context of inflammatory processes. We also summarize the adaptive cellular responses activated during proteasome inhibition with special emphasis on the activation of the Autophagic-Lysosomal Pathway (ALP), proteaphagy, p62/SQSTM1 enriched-inclusion bodies, and proteasome biogenesis dependent on Nrf1 and Nrf2 transcription factors. Moreover, we discuss the role of IRE1 and PERK sensors in ALP activation during ER stress and the involvement of two deubiquitinases, Rpn11 and USP14, in these processes. Finally, we discuss the aspects that should be currently considered in the development of novel strategies that use proteasome activity as a therapeutic target for the treatment of human diseases.

Effects of nutrients and water levels on emergent macrophyte biomass in a prairie marsh

1990 ◽  
Vol 68 (5) ◽  
pp. 1007-1014 ◽  
Author(s):  
Christopher Neill
Keyword(s):  
Water Level ◽  
Nutrient Limitation ◽  
Water Depth ◽  
Nitrogen Limitation ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Depth Range ◽  
Dry Conditions ◽  
Second Year ◽  
Water Depths

Nitrogen and phosphorus fertilizers were added over two growing seasons to marshes dominated by whitetop grass (Scolochloa festucacea) or cattail (Typha glauca) in a prairie lacustrine marsh to assess nutrient limitation and the interaction of nutrient limitation with water depth. For each species, stands were selected at the deep and shallow extremes of its water depth range. Water levels were high during the first year of fertilization and low during the second year, exposing the fertilized stands to a variety of water depths. Nitrogen limited growth in whitetop and cattail marshes. Water level, by controlling whether the soil was flooded or the water table was below the soil surface, affected growth and the degree of nitrogen limitation. In whitetop marshes, nitrogen increased biomass more when the soil was flooded or when standing water was deeper and in cattail marshes, it increased biomass more under intermediate water depths (approximately 0–20 cm) than under more deeply flooded (20–40 cm) or dry conditions. Nitrogen reduced biomass in whitetop marshes the second year, apparently because growth was inhibited by fallen litter from the previous year. Nitrogen did not limit cattail marsh biomass in the driest locations during a year of low water levels. Phosphorus caused a small increase in growth of both species after 2 years. Changes of nitrogen limitation with flooding suggest that annual water level fluctuations, by creating alternating flooded and dry conditions, may influence the primary production of emergent macrophytes through effects on nitrogen cycling.

Identification of genes induced in proteoid roots of white lupin under nitrogen and phosphorus deprivation, with functional characterization of a formamidase

2010 ◽  
Vol 334 (1-2) ◽  
pp. 137-150 ◽  
Author(s):  
Mousumi Rath ◽  
Jay Salas ◽  
Bandita Parhy ◽  
Robert Norton ◽  
Himabindu Menakuru ◽  
...  
Keyword(s):  
Functional Characterization ◽  
White Lupin ◽  
Nitrogen And Phosphorus ◽  
Proteoid Roots ◽  
Phosphorus Deprivation

scholarly journals Adaptation of the Photosynthetic Apparatus in Maize Leaves as a Result of Nitrogen Limitation

1990 ◽  
Vol 94 (3) ◽  
pp. 1436-1443 ◽  
Author(s):  
Saadi Khamis ◽  
Thierry Lamaze ◽  
Yves Lemoine ◽  
Christine Foyer
Keyword(s):  
Nitrogen Limitation ◽  
Photosynthetic Apparatus ◽  
Maize Leaves
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