scholarly journals Phytohormone up-regulates the biochemical constituent, exopolysaccharide and nitrogen metabolism in paddy-field cyanobacteria exposed to chromium stress

2020 ◽  
Author(s):  
Sanjesh Tiwari ◽  
Anuradha Patel ◽  
Sheo Mohan Prasad
Keyword(s):  
Nitrogen Metabolism ◽  
Uptake Rate ◽  
Paddy Field ◽  
Growth Parameter ◽  
Glutamate Synthase ◽  
Nostoc Muscorum ◽  
Biochemical Constituent ◽  
Diazotrophic Cyanobacteria ◽  
Chromium Stress ◽  
Cr Uptake

Abstract Current study deals with the assuaging effects of two phytohormones; indole acetic acid (IAA; 290 nM) and kinetin (KN; 10 nM) on growth, phycobiliproteins, status of nitrogen metabolism and biochemical constituents; protein, carbohydrate and exopolysaccharide contents in two diazotrophic cyanobacteria Nostoc muscorum and Anabaena exposed to chromium (CrVI) stress (100 µM and 150 µM). Chromium individually at both the tested doses expressively declined the growth, chlorophyll a to carotenoid ratio and contents of phycobiliproteins; phycocyanin (PC), allophycocyanin (APC), and phycoerythrin (PE). With distinctive impact on status of nitrogen metabolism chromium significantly reduced the nitrate (NO3—) and nitrite (NO2—) uptake rate and foremost decrease in nitrate and ammonia assimilating enzyme; nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (GOGAT) except glutamate dehydrogenase (GDH). However, beneath alike condition, exogenous application of IAA and KN exhibited noteworthy assuaging effects on growth-regulating parameters in both the paddy field cyanobacteria, which consummately occurred as a result of substantial decrease in Cr uptake and inducing signaling responses and also enhances the growth parameter i.e. nitrogen metabolism as a result of considerable lowering in Cr induced damaging effect on nitrogen metabolism and uptake rate, and the alleviating effect was more pronounced with the lower dose of Cr, efficient in N.muscorum than Anabaena.

scholarly journals Phytohormone up-regulates the biochemical constituent, exopolysaccharide and nitrogen metabolism in paddy-field cyanobacteria exposed to chromium stress

2020 ◽  
Author(s):  
Sanjesh Tiwari ◽  
Anuradha Patel ◽  
Sheo Mohan Prasad
Keyword(s):  
Nitrogen Metabolism ◽  
Paddy Field ◽  
Biochemical Constituent ◽  
Chromium Stress ◽  
Journal Submission

Abstract The authors have withdrawn the journal submission associated with this preprint and requested that the preprint also be withdrawn.

Glutamate synthase levels in Neurospora crassa mutants altered with respect to nitrogen metabolism

1981 ◽  
Vol 1 (2) ◽  
pp. 158-164
Author(s):  
N S Dunn-Coleman ◽  
E A Robey ◽  
A B Tomsett ◽  
R H Garrett
Keyword(s):  
Neurospora Crassa ◽  
Glutamate Dehydrogenase ◽  
Nitrogen Metabolism ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Glutamate Synthase ◽  
Wild Type ◽  
Mutant Strains ◽  
Synthase Regulation ◽  
Glutamate Biosynthesis ◽  
Glutamine Limitation

Glutamate synthase catalyzes glutamate formation from 2-oxoglutarate plus glutamine and plays an essential role when glutamate biosynthesis by glutamate dehydrogenase is not possible. Glutamate synthase activity has been determined in a number of Neurospora crassa mutant strains with various defects in nitrogen metabolism. Of particular interest were two mutants phenotypically mute except in an am (biosynthetic nicotinamide adenine dinucleotide phosphate-glutamate dehydrogenase deficient, glutamate requiring) background. These mutants, i and en-am, are so-called enhancers of am; they have been redesignated herein as en(am)-1 and en(am)-2, respectively. Although glutamate synthase levels in en(am)-1 were essentially wild type, the en(am)-2 strain was devoid of glutamate synthase activity under all conditions examined, suggesting that en(am)-2 may be the structural locus for glutamate synthase. Regulation of glutamate synthase occurred to some extent, presumably in response to glutamate requirements. Glutamate starvation, as in am mutants, led to enhanced activity. In contrast, glutamine limitation, as in gln-1 mutants, depressed glutamate synthase levels.

scholarly journals Glutamate synthase levels in Neurospora crassa mutants altered with respect to nitrogen metabolism.

1981 ◽  
Vol 1 (2) ◽  
pp. 158-164 ◽  
Author(s):  
N S Dunn-Coleman ◽  
E A Robey ◽  
A B Tomsett ◽  
R H Garrett
Keyword(s):  
Neurospora Crassa ◽  
Glutamate Dehydrogenase ◽  
Nitrogen Metabolism ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Glutamate Synthase ◽  
Wild Type ◽  
Mutant Strains ◽  
Synthase Regulation ◽  
Glutamate Biosynthesis ◽  
Glutamine Limitation

Glutamate synthase catalyzes glutamate formation from 2-oxoglutarate plus glutamine and plays an essential role when glutamate biosynthesis by glutamate dehydrogenase is not possible. Glutamate synthase activity has been determined in a number of Neurospora crassa mutant strains with various defects in nitrogen metabolism. Of particular interest were two mutants phenotypically mute except in an am (biosynthetic nicotinamide adenine dinucleotide phosphate-glutamate dehydrogenase deficient, glutamate requiring) background. These mutants, i and en-am, are so-called enhancers of am; they have been redesignated herein as en(am)-1 and en(am)-2, respectively. Although glutamate synthase levels in en(am)-1 were essentially wild type, the en(am)-2 strain was devoid of glutamate synthase activity under all conditions examined, suggesting that en(am)-2 may be the structural locus for glutamate synthase. Regulation of glutamate synthase occurred to some extent, presumably in response to glutamate requirements. Glutamate starvation, as in am mutants, led to enhanced activity. In contrast, glutamine limitation, as in gln-1 mutants, depressed glutamate synthase levels.

scholarly journals Roles of Glutamate Synthase, gltBD, and gltF in Nitrogen Metabolism of Escherichia coli and Klebsiella aerogenes

2001 ◽  
Vol 183 (22) ◽  
pp. 6607-6619 ◽  
Author(s):  
Thomas J. Goss ◽  
Ana Perez-Matos ◽  
Robert A. Bender
Keyword(s):  
Escherichia Coli ◽  
Nitrogen Metabolism ◽  
Glutamate Synthase ◽  
Nitrogen Sources ◽  
Enteric Bacteria ◽  
The Other ◽  
Klebsiella Aerogenes ◽  
E Coli ◽  
Glutamine Synthesis ◽  
Subsequent Failure

ABSTRACT Mutants of Escherichia coli and Klebsiella aerogenes that are deficient in glutamate synthase (glutamate-oxoglutarate amidotransferase [GOGAT]) activity have difficulty growing with nitrogen sources other than ammonia. Two models have been proposed to account for this inability to grow. One model postulated an imbalance between glutamine synthesis and glutamine degradation that led to a repression of the Ntr system and the subsequent failure to activate transcription of genes required for the use of alternative nitrogen sources. The other model postulated that mutations in gltB or gltD (which encode the subunits of GOGAT) were polar on a downstream gene,gltF, which is necessary for proper activation of gene expression by the Ntr system. The data reported here show that thegltF model is incorrect for three reasons: first, a nonpolar gltB and a polar gltD mutation of K. aerogenes both show the same phenotype; second,K. aerogenes and several other enteric bacteria lack a gene homologous to gltF; and third, mutants of E. coli whose gltF gene has been deleted show no defect in nitrogen metabolism. The argument that accumulated glutamine represses the Ntr system in gltB or gltDmutants is also incorrect, because these mutants can derepress the Ntr system normally so long as sufficient glutamate is supplied. Thus, we conclude that gltB or gltD mutants grow slowly on many poor nitrogen sources because they are starved for glutamate. Much of the glutamate formed by catabolism of alternative nitrogen sources is converted to glutamine, which cannot be efficiently converted to glutamate in the absence of GOGAT activity. Finally, GOGAT-deficient E. coli cells growing with glutamine as the sole nitrogen source increase their synthesis of the other glutamate-forming enzyme, glutamate dehydrogenase, severalfold, but this is still insufficient to allow rapid growth under these conditions.

scholarly journals Localization, Gene Expression, and Functions of Glutamine Synthetase Isozymes in Wheat Grain (Triticum aestivum L.)

2021 ◽  
Vol 12 ◽  
Author(s):  
Yihao Wei ◽  
Shuping Xiong ◽  
Zhiyong Zhang ◽  
Xiaodan Meng ◽  
Lulu Wang ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Metabolism ◽  
Glutamate Synthase ◽  
Grain Filling ◽  
Maximum Activity ◽  
Transfer Cells ◽  
Aleurone Layer ◽  
Wheat Grain ◽  
Plant Nitrogen ◽  
Endosperm Transfer Cells

Glutamine synthetase (GS) plays a major role in plant nitrogen metabolism, but the roles of individual GS isoforms in grains are unknown. Here, the localization and expression of individual TaGS isozymes in wheat grain were probed with TaGS isoenzyme-specific antibodies, and the nitrogen metabolism of grain during the grain filling stage were investigated. Immunofluorescence revealed that TaGS1;1, TaGS1;3, and TaGS2 were expressed in different regions of the embryo. In grain transporting tissues, TaGS1;2 was localized in vascular bundle; TaGS1;2 and TaGS1;1 were in chalaza and placentochalaza; TaGS1;1 and TaGS1;3 were in endosperm transfer cells; and TaGS1;3 and TaGS2 were in aleurone layer. GS exhibited maximum activity and expression at 8 days after flowering (DAF) with peak glutamine content in grains; from then, NH4+ increased largely from NO3- reduction, glutamate dehydrogenase (GDH) aminating activity increased continuously, and the activities of GS and glutamate synthase (GOGAT) decreased, while only TaGS1;3 kept a stable expression in different TaGS isozymes. Hence, GS-GOGAT cycle and GDH play different roles in NH4+ assimilation of grain in different stages of grain development; TaGS1;3, located in aleurone layer and endosperm transfer cells, plays a key role in Gln into endosperm for gluten synthesis. At 30 DAF, grain amino acids are mainly transported from maternal phloem.

The glutamate synthase (GOGAT) of plays an important role in central nitrogen metabolism

2001 ◽  
Vol 1 (3) ◽  
pp. 169-175 ◽  
Author(s):  
J GUILLAMON ◽  
N VANRIEL ◽  
M GIUSEPPIN ◽  
C VERRIPS
Keyword(s):  
Nitrogen Metabolism ◽  
Glutamate Synthase
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