Nitric oxide detoxification in the rhizobia–legume symbiosis

2011 ◽  
Vol 39 (1) ◽  
pp. 184-188 ◽  
Author(s):  
Cristina Sánchez ◽  
Juan J. Cabrera ◽  
Andrew J. Gates ◽  
Eulogio J. Bedmar ◽  
David J. Richardson ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Current Knowledge ◽  
Nitrogenase Activity ◽  
Free Living ◽  
Signal Molecule ◽  
Physiological Processes ◽  
Endosymbiotic Bacteria ◽  
Legume Symbiosis ◽  
And Diffusion ◽  
Review Current

NO (nitric oxide) is a signal molecule involved in diverse physiological processes in cells which can become very toxic under certain conditions determined by its rate of production and diffusion. Several studies have clearly shown the production of NO in early stages of rhizobia–legume symbiosis and in mature nodules. In functioning nodules, it has been demonstrated that NO, which has been reported as a potent inhibitor of nitrogenase activity, can bind Lb (leghaemoglobin) to form LbNOs (nitrosyl–leghaemoglobin complexes). These observations have led to the question of how nodules overcome the toxicity of NO. On the bacterial side, one candidate for NO detoxification in nodules is the respiratory Nor (NO reductase) that catalyses the reduction of NO to nitrous oxide. In addition, rhizobial fHbs (flavohaemoglobins) and single-domain Hbs which dioxygenate NO to form nitrate are candidates to detoxify NO under free-living and symbiotic conditions. On the plant side, sHbs (symbiotic Hbs) (Lb) and nsHbs (non-symbiotic Hbs) have been proposed to play important roles as modulators of NO levels in the rhizobia–legume symbiosis. In the present review, current knowledge of NO detoxification by legume-associated endosymbiotic bacteria is summarized.

scholarly journals The nitric oxide response in plant-associated endosymbiotic bacteria

2011 ◽  
Vol 39 (6) ◽  
pp. 1880-1885 ◽  
Author(s):  
Juan J. Cabrera ◽  
Cristina Sánchez ◽  
Andrew J. Gates ◽  
Eulogio J. Bedmar ◽  
Socorro Mesa ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Sinorhizobium Meliloti ◽  
Current Knowledge ◽  
Bacterial Cells ◽  
Cellular Targets ◽  
Endosymbiotic Bacteria ◽  
Signalling Molecule ◽  
Genes Encoding ◽  
Rhizobial Species ◽  
Legume Symbiosis

Nitric oxide (NO) is a gaseous signalling molecule which becomes very toxic due to its ability to react with multiple cellular targets in biological systems. Bacterial cells protect against NO through the expression of enzymes that detoxify this molecule by oxidizing it to nitrate or reducing it to nitrous oxide or ammonia. These enzymes are haemoglobins, c-type nitric oxide reductase, flavorubredoxins and the cytochrome c respiratory nitrite reductase. Expression of the genes encoding these enzymes is controlled by NO-sensitive regulatory proteins. The production of NO in rhizobia–legume symbiosis has been demonstrated recently. In functioning nodules, NO acts as a potent inhibitor of nitrogenase enzymes. These observations have led to the question of how rhizobia overcome the toxicity of NO. Several studies on the NO response have been undertaken in two non-dentrifying rhizobial species, Sinorhizobium meliloti and Rhizobium etli, and in a denitrifying species, Bradyrhizobium japonicum. In the present mini-review, current knowledge of the NO response in those legume-associated endosymbiotic bacteria is summarized.

scholarly journals Production of Nitric Oxide and Nitrosylleghemoglobin Complexes in Soybean Nodules in Response to Flooding

2010 ◽  
Vol 23 (5) ◽  
pp. 702-711 ◽  
Author(s):  
Cristina Sánchez ◽  
Andrew J. Gates ◽  
Georgina E. Meakin ◽  
Toshiki Uchiumi ◽  
Lourdes Girard ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrite Reductase ◽  
Nitrogenase Activity ◽  
Environmental Cues ◽  
Wild Type ◽  
Free Living ◽  
No Formation ◽  
Symbiotic Interactions ◽  
Negative Effect ◽  
Free Living Conditions

Nitric oxide (NO) has gained interest as a major signaling molecule during plant development and in response to environmental cues. Formation of NO during symbiotic interactions has been reported, but the role and sources of NO in nodules remain unclear. In this work, the involvement of denitrification, performed by the symbiont Bradyrhizobium japonicum, in NO formation in soybean nodules in response to flooding conditions has been investigated by inoculating plants with napA-, nirK-, or norC-deficient mutants. Levels of nitrosylleghemoglobin (LbNO) in flooded nirK and norC nodules were significantly higher than those observed in wild-type nodules. In addition, nirK and norC nodules accumulated more nitrite and NO, respectively, than wild-type nodules. By contrast, levels of LbNO, nitrite, and NO in flooded napA nodules were lower than in wild-type nodules. These results suggest that LbNO formation in soybean nodules in response to flooding conditions is caused by nitrite and NO generated from periplasmic nitrate reductase (Nap) and also containing nitrite reductase (NirK) denitrification enzymes. Flooding caused a decrease of nifH expression and nitrogenase activity in wild-type and norC nodules but not in napA or nirK nodules. Incubation of wild-type and norC nodules with a NO scavenger counteracted the effect of flooding. Under free-living conditions, β-galactosidase activity from a nifD′-′lacZ fusion decreased in a norC mutant, which also accumulated NO in the medium. These results suggest that NO formed by Cu-containing nitrite reductase in soybean nodules in response to flooding has a negative effect on expression of nitrogenase. We propose that Lb has a major role in detoxifying NO and nitrite produced by bacteroidal denitrification in response to flooding conditions.

scholarly journals Hypothetical orchestrated cooperation between dopaminergic and kinin receptors for the regulation of common functions

2016 ◽  
Vol 63 (3) ◽  
Author(s):  
Ibeth Guevara-Lora ◽  
Anna Niewiarowska-Sendo ◽  
Agnieszka Polit ◽  
Andrzej Kozik
Keyword(s):  
Dopamine Receptors ◽  
Current Knowledge ◽  
Signal Transmission ◽  
Physiological Processes ◽  
Kinin Receptors ◽  
Essential Components ◽  
G Protein Coupled ◽  
Review Current ◽  
Signal Transduction Systems

The G protein-coupled receptors (GPCRs), one of the largest protein families, are essential components of the most commonly used signal-transduction systems in cells. These receptors, often using common pathways, may cooperate in the regulation of signal transmission to the cell nucleus. Recent scientific interests increasingly focus on the cooperation between these receptors, particularly in a context of their oligomerization, e.g. the formation of dimers that are able to change characteristic signaling of each receptor. Numerous studies on kinin and dopamine receptors which belong to this family of receptors have shown new facts demonstrating their direct interactions with other GPCRs. In this review, current knowledge on signaling pathways and oligomerization of these receptors has been summarized. Owing to the fact that kinin and dopamine receptors are widely expressed in cell membranes where they act as mediators of numerous common physiological processes, the information presented here sheds new light on a putative crosstalk of these receptors and provides more comprehensive understanding of possible direct interactions that may change their functions. The determination of such interactions may be useful for the development of new targeted therapeutic strategies against many disorders in which kinin and dopamine receptors are involved.

scholarly journals Cord Blood-Based Approach to Assess Candidate Vaccine Adjuvants Designed for Neonates and Infants

Vaccines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 95
Author(s):  
Daisuke Tokuhara ◽  
Norikatsu Hikita
Keyword(s):  
Cord Blood ◽  
Protective Immunity ◽  
Current Knowledge ◽  
Current System ◽  
Innate Immune ◽  
Vaccine Adjuvants ◽  
Adult Humans ◽  
Neonates And Infants ◽  
Induced Immunity ◽  
Review Current

Neonates and infants are particularly susceptible to infections, for which outcomes tend to be severe. Vaccination is a key strategy for preventing infectious diseases, but the protective immunity achieved through vaccination typically is weaker in infants than in healthy adults. One possible explanation for the poor acquisition of vaccine-induced immunity in infants is that their innate immune response, represented by toll-like receptors, is immature. The current system for developing pediatric vaccines relies on the confirmation of their safety and effectiveness in studies involving the use of mature animals or adult humans. However, creating vaccines for neonates and infants requires an understanding of their uniquely immature innate immunity. Here we review current knowledge regarding the innate immune system of neonates and infants and challenges in developing vaccine adjuvants for those children through analyses of cord blood.

Nitric oxide signalling in plant interactions with pathogenic fungi and oomycetes

2020 ◽  
Author(s):  
Tereza Jedelská ◽  
Lenka Luhová ◽  
Marek Petřivalský
Keyword(s):  
Nitric Oxide ◽  
Current Knowledge ◽  
Biotic Interactions ◽  
Decisive Role ◽  
Pathogenic Fungi ◽  
Plant Colonization ◽  
No Production ◽  
Plant Interactions ◽  
Oriented Growth ◽  
Plant Pathogen Interactions

Abstract Nitric oxide (NO) and reactive nitrogen species have emerged as crucial signalling and regulatory molecules across all organisms. In plants, fungi and fungi-like oomycetes, NO is involved in the regulation of multiple processes during their growth, development, reproduction, responses to the external environment and biotic interactions. It has become evident that NO is produced and used as signalling and defence cues by both partners in multiple forms of plant interactions with their microbial counterparts, ranging from symbiotic to pathogenic modes. This review summarizes current knowledge on NO role in plant-pathogen interactions, focused on biotrophic, necrotrophic and hemibiotrophic fungi and oomycetes. Actual advances and gaps in the identification of NO sources and fate in plant and pathogen cells are discussed. We review the decisive role of time- and site-specific NO production in germination, oriented growth and active penetration of filamentous pathogens to the host tissues, as well in pathogen recognition, and defence activation in plants. Distinct functions of NO are highlighted on diverse interactions of host plants with fungal and oomycete pathogens of different lifestyles, where NO in interplay with reactive oxygen species govern successful plant colonization, cell death and resistance establishment.

scholarly journals The Multiple Functions of Rho GTPases in Fission Yeasts

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1422
Author(s):  
Jero Vicente-Soler ◽  
Teresa Soto ◽  
Alejandro Franco ◽  
José Cansado ◽  
Marisa Madrid
Keyword(s):  
Fission Yeast ◽  
Rho Gtpases ◽  
Current Knowledge ◽  
Model Organism ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Physiological Processes ◽  
Evolutionary Changes ◽  
Rho Family

The Rho family of GTPases represents highly conserved molecular switches involved in a plethora of physiological processes. Fission yeast Schizosaccharomyces pombe has become a fundamental model organism to study the functions of Rho GTPases over the past few decades. In recent years, another fission yeast species, Schizosaccharomyces japonicus, has come into focus offering insight into evolutionary changes within the genus. Both fission yeasts contain only six Rho-type GTPases that are spatiotemporally controlled by multiple guanine–nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), and whose intricate regulation in response to external cues is starting to be uncovered. In the present review, we will outline and discuss the current knowledge and recent advances on how the fission yeasts Rho family GTPases regulate essential physiological processes such as morphogenesis and polarity, cellular integrity, cytokinesis and cellular differentiation.

scholarly journals Paraburkholderia phymatum Homocitrate Synthase NifV Plays a Key Role for Nitrogenase Activity during Symbiosis with Papilionoids and in Free-Living Growth Conditions

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 952
Author(s):  
Paula Bellés-Sancho ◽  
Martina Lardi ◽  
Yilei Liu ◽  
Sebastian Hug ◽  
Marta Adriana Pinto-Carbó ◽  
...  
Keyword(s):  
Nitrogenase Activity ◽  
Root Nodules ◽  
Growth Conditions ◽  
Lysine Biosynthesis ◽  
Metabolome Analysis ◽  
Plant Host ◽  
Free Living ◽  
Bacterial Enzyme ◽  
Homocitrate Synthase ◽  
Iron Molybdenum Cofactor

Homocitrate is an essential component of the iron-molybdenum cofactor of nitrogenase, the bacterial enzyme that catalyzes the reduction of dinitrogen (N2) to ammonia. In nitrogen-fixing and nodulating alpha-rhizobia, homocitrate is usually provided to bacteroids in root nodules by their plant host. In contrast, non-nodulating free-living diazotrophs encode the homocitrate synthase (NifV) and reduce N2 in nitrogen-limiting free-living conditions. Paraburkholderia phymatum STM815 is a beta-rhizobial strain, which can enter symbiosis with a broad range of legumes, including papilionoids and mimosoids. In contrast to most alpha-rhizobia, which lack nifV, P. phymatum harbors a copy of nifV on its symbiotic plasmid. We show here that P. phymatum nifV is essential for nitrogenase activity both in root nodules of papilionoid plants and in free-living growth conditions. Notably, nifV was dispensable in nodules of Mimosa pudica despite the fact that the gene was highly expressed during symbiosis with all tested papilionoid and mimosoid plants. A metabolome analysis of papilionoid and mimosoid root nodules infected with the P. phymatum wild-type strain revealed that among the approximately 400 measured metabolites, homocitrate and other metabolites involved in lysine biosynthesis and degradation have accumulated in all plant nodules compared to uninfected roots, suggesting an important role of these metabolites during symbiosis.

scholarly journals Meteorite Orbits from Observations by Camera Networks

1983 ◽  
Vol 6 ◽  
pp. 399-404 ◽  
Author(s):  
Ian Halliday ◽  
Arthur A. Griffin ◽  
Alan T. Blackwell
Keyword(s):  
Current Knowledge ◽  
Great Difficulty ◽  
Camera Networks ◽  
Significant Group ◽  
Lost City ◽  
Knowledge Based ◽  
Alternative Approach ◽  
Physically Identical ◽  
Review Current ◽  
Visual Observations

Camera networks for the study of bright fireballs now have a history approaching two decades• It was hoped that the networks would produce a statistically significant group of recovered meteorites with accurate orbits. Due to the great difficulty in locating the meteorites from a photographed event, there are still only three meteorites with orbits determined from suitable photographs; Pribram, Lost City and Innisfree (Ceplecha I96I, McCrosky et al. 1971, Halliday et al. 1978, respectively). Networks do, however, provide an alternative approach to the problem. Instead of determining approximate orbits from visual observations of recovered meteorite falls, it is now preferable to use reliable orbits from the camera networks for fireballs which are believed to have dropped meteorites that could not be located, or, that are believed to have been physically identical to meteorites, although no appreciable mass survived the atmospheric flight. This paper will review current knowledge based on this approach to the problem.

scholarly journals Early Developmental Conditioning of Later Health and Disease: Physiology or Pathophysiology?

2014 ◽  
Vol 94 (4) ◽  
pp. 1027-1076 ◽  
Author(s):  
M. A. Hanson ◽  
P. D. Gluckman
Keyword(s):  
Animal Studies ◽  
Developmental Plasticity ◽  
Current Knowledge ◽  
Evolutionary Developmental Biology ◽  
Noncommunicable Disease ◽  
Normal Range ◽  
Physiological Processes ◽  
New Concepts ◽  
Health And Disease ◽  
Underlying Mechanisms

Extensive experimental animal studies and epidemiological observations have shown that environmental influences during early development affect the risk of later pathophysiological processes associated with chronic, especially noncommunicable, disease (NCD). This field is recognized as the developmental origins of health and disease (DOHaD). We discuss the extent to which DOHaD represents the result of the physiological processes of developmental plasticity, which may have potential adverse consequences in terms of NCD risk later, or whether it is the manifestation of pathophysiological processes acting in early life but only becoming apparent as disease later. We argue that the evidence suggests the former, through the operation of conditioning processes induced across the normal range of developmental environments, and we summarize current knowledge of the physiological processes involved. The adaptive pathway to later risk accords with current concepts in evolutionary developmental biology, especially those concerning parental effects. Outside the normal range, effects on development can result in nonadaptive processes, and we review their underlying mechanisms and consequences. New concepts concerning the underlying epigenetic and other mechanisms involved in both disruptive and nondisruptive pathways to disease are reviewed, including the evidence for transgenerational passage of risk from both maternal and paternal lines. These concepts have wider implications for understanding the causes and possible prevention of NCDs such as type 2 diabetes and cardiovascular disease, for broader social policy and for the increasing attention paid in public health to the lifecourse approach to NCD prevention.

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