Carbon and nitrogen partitioning in young nodulated pea (wild type and nitrate reductase-deficient mutant) plants exposed to NO3− or NH4+

1991 ◽  
Vol 69 (8) ◽  
pp. 1780-1786 ◽  
Author(s):  
Barry J. Shelp ◽  
David C. Taylor ◽  
Louise M. Nelson
Keyword(s):  
Nitrate Reductase ◽  
Rhizobium Leguminosarum ◽  
Nitrogenase Activity ◽  
Nitrogen Partitioning ◽  
Deficient Mutant ◽  
Wild Type ◽  
Inorganic N ◽  
Carbon And Nitrogen ◽  
Pisum Sativum L ◽  
In The Wild

Fresh weight accumulation, and carbon and nitrogen partitioning were investigated in wild type and a nitrate reductase-deficient mutant (A317) of Pisum sativum L. (cv. Juneau), effectively inoculated with Rhizobium leguminosarum strain 128C54. The plants were grown hydroponically in medium without combined N for 21 days, followed by a further 7 days in medium without combined N or with 5 mM NO3− or NH4+. In the absence of combined N, the nitrogenase activity (measured as acetylene reduction and expressed on a specific nodule basis) of A317 was 53% of the wild type. In the presence of combined N the nitrogenase activity of wild-type plants was reduced by 60%, whereas that of A317 was not affected. The decline in the proportion of 14C translocated to nodulated roots that was allocated to nodules only was significant in the wild type. Inorganic N accumulated in the nodule. Nodule concentrations of asparagine and glutamine increased dramatically in both genotypes with NH4+ but not NO3−. The partitioning of sugar and starch was often dependent on the pea genotype and N form. These data suggest that the assimilation of NO3− and (or) NH4+ plays a role in the inhibition of symbiotic N2 fixation by combined N. Key words: carbon and nitrogen partitioning, nitrate reductase, nodulated pea plants.

scholarly journals Expression of glnB and aglnB-Like Gene (glnK) in a Ribulose Bisphosphate Carboxylase/Oxygenase-Deficient Mutant of Rhodobacter sphaeroides

1998 ◽  
Vol 180 (17) ◽  
pp. 4644-4649 ◽  
Author(s):  
Yilei Qian ◽  
F. Robert Tabita
Keyword(s):  
Rhodobacter Sphaeroides ◽  
Nitrogenase Activity ◽  
Growth Conditions ◽  
Ribulose Bisphosphate Carboxylase ◽  
Deficient Mutant ◽  
Wild Type ◽  
Bisphosphate Carboxylase ◽  
Negative Effect ◽  
In The Wild ◽  
Photoheterotrophic Growth

ABSTRACT In a ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO)-deficient mutant of Rhodobacter sphaeroides, strain 16PHC, nitrogenase activity was derepressed in the presence of ammonia under photoheterotrophic growth conditions. Previous studies also showed that reintroduction of a functional RubisCO and Calvin-Benson-Bassham (CBB) pathway suppressed the deregulation of nitrogenase synthesis in this strain. In this study, the derepression of nitrogenase synthesis in the presence of ammonia in strain 16PHC was further explored by using aglnB::lacZ fusion, since the product of the glnB gene is known to have a negative effect on ammonia-regulated nif control. It was found thatglnB expression was repressed in strain 16PHC under photoheterotrophic growth conditions with either ammonia or glutamate as the nitrogen source; glutamine synthetase (GS) levels were also affected in this strain. However, when cells regained a functional CBB pathway by trans complementation of the deleted genes, wild-type levels of GS and glnB expression were restored. Furthermore, a glnB-like gene,glnK, was isolated from this organism, and its expression was found to be under tight nitrogen control in the wild type. Surprisingly, glnK expression was found to be derepressed in strain 16PHC under photoheterotrophic conditions in the presence of ammonia.

Characterization of some non-fixing mutants of common bean (Phaseolus vulgaris L.)

1993 ◽  
Vol 73 (4) ◽  
pp. 977-983 ◽  
Author(s):  
B. R. Buttery ◽  
S. J. Park
Keyword(s):  
Phaseolus Vulgaris ◽  
Nitrate Reductase ◽  
Common Bean ◽  
Rhizobium Leguminosarum ◽  
Variable Number ◽  
Wild Type ◽  
Parent Line ◽  
Rhizobium Strains ◽  
Wild Type Parent

With 18 strains of Rhizobium leguminosarum bv. phaseoli the bean mutants R99 and NOD125 remained essentially non-nodulating, while the mutant R69 produced a variable number of small white ineffective nodules, and the wild-type parent-line OAC Rico formed a variable number of pink effective nodules. Both R69 and R99 grew less vigorously than OAC Rico, but possessed similar levels of nitrate reductase in both roots and leaves, and responded in a normal way to increased supply of combined nitrogen. Reciprocal grafts between the non-nodulating R99 and NOD125, the ineffective R69, the wild-type parent line OAC Rico, and the supernodulating R32BS, demonstrated that the non-nodulating and ineffective characters were controlled by the root, and confirmed that the supernodulation character was controlled by the shoot. Key words: Common bean, nitrate reductase, non-fixing mutants, Phaseolus vulgaris, Rhizobium strains, supernodulation

scholarly journals Involvement of H-NS in Transpositional Recombination Mediated by IS1

2001 ◽  
Vol 183 (8) ◽  
pp. 2476-2484 ◽  
Author(s):  
Yasuyuki Shiga ◽  
Yasuhiko Sekine ◽  
Yasunobu Kano ◽  
Eiichi Ohtsubo
Keyword(s):  
Dna Binding ◽  
Wild Type Strain ◽  
Integration Host Factor ◽  
Deficient Mutant ◽  
Wild Type ◽  
Transposase Gene ◽  
In The Wild ◽  
Transposition Reaction ◽  
Target Plasmid

ABSTRACT IS1, the smallest active transposable element in bacteria, encodes a transposase that promotes inter- and intramolecular transposition. Host-encoded factors, e.g., histone-like proteins HU and integration host factor (IHF), are involved in the transposition reactions of some bacterial transposable elements. Host factors involved in the IS1 transposition reaction, however, are not known. We show that a plasmid with an IS1 derivative that efficiently produces transposase did not generate miniplasmids, the products of intramolecular transposition, in mutants deficient in a nucleoid-associated DNA-binding protein, H-NS, but did generate them in mutants deficient in histone-like proteins HU, IHF, Fis, and StpA. Nor did IS1 transpose intermolecularly to the target plasmid in the H-NS-deficient mutant. The hns mutation did not affect transcription from the indigenous promoter of IS1 for the expression of the transposase gene. These findings show that transpositional recombination mediated by IS1 requires H-NS but does not require the HU, IHF, Fis, or StpA protein in vivo. Gel retardation assays of restriction fragments of IS1-carrying plasmid DNA showed that no sites were bound preferentially by H-NS within the IS1 sequence. The central domain of H-NS, which is involved in dimerization and/or oligomerization of the H-NS protein, was important for the intramolecular transposition of IS1, but the N- and C-terminal domains, which are involved in the repression of certain genes and DNA binding, respectively, were not. The SOS response induced by the IS1 transposase was absent in the H-NS-deficient mutant strain but was present in the wild-type strain. We discuss the possibility that H-NS promotes the formation of an active IS1 DNA-transposase complex in which the IS1 ends are cleaved to initiate transpositional recombination through interaction with IS1 transposase.

Phosphatidylinositol phospholipase C mediates carbon sensing and vegetative nuclear duplication rates in Aspergillus nidulans

2011 ◽  
Vol 57 (7) ◽  
pp. 611-616 ◽  
Author(s):  
Ana Paula de Figueiredo Conte Vanzela ◽  
Suraia Said ◽  
Rolf Alexander Prade
Keyword(s):  
Molecular Weight ◽  
Carbon Source ◽  
Phospholipase C ◽  
Aspergillus Nidulans ◽  
Nuclear Division ◽  
Deficient Mutant ◽  
Wild Type ◽  
Pectinolytic Enzymes ◽  
In The Wild ◽  
Phosphatidylinositol Phospholipase C

In this work, we disrupted one of three putative phosphatidylinositol phospholipase C genes of Aspergillus nidulans and studied its effect on carbon source sensing linked to vegetative mitotic nuclear division. We showed that glucose does not affect nuclear division rates during early vegetative conidial germination (6–7 h) in either the wild type or the plcA-deficient mutant. Only after 8 h of cultivation on glucose did the mutant strain present some decrease in nuclear duplication. However, decreased nuclear division rates were observed in the wild type when cultivated in media amended with polypectate, whereas our plcA-deficient mutant did not show slow nuclear duplication rates when grown on this carbon source, even though it requires induction and secretion of multiple pectinolytic enzymes to be metabolized. Thus, plcA appears to be directly linked to high-molecular-weight carbon source sensing.

scholarly journals Mesophyll conductance decreases in the wild type but not in an ABA-deficient mutant (aba1) ofNicotiana plumbaginifoliaunder drought conditions

2014 ◽  
Vol 38 (3) ◽  
pp. 388-398 ◽  
Author(s):  
YUSUKE MIZOKAMI ◽  
KO NOGUCHI ◽  
MIKIKO KOJIMA ◽  
HITOSHI SAKAKIBARA ◽  
ICHIRO TERASHIMA
Keyword(s):  
Mesophyll Conductance ◽  
Deficient Mutant ◽  
Wild Type ◽  
Drought Conditions ◽  
In The Wild

scholarly journals Regulation of nitrate reductase of Neurospora at the level of transcription and translation

1973 ◽  
Vol 134 (3) ◽  
pp. 673-685 ◽  
Author(s):  
G. J. Sorger ◽  
J. Davies
Keyword(s):  
Nitrate Reductase ◽  
Type Strain ◽  
Wild Type Strain ◽  
Reductase Activity ◽  
Nitrogen Sources ◽  
Normal Strain ◽  
Wild Type ◽  
Benzyl Viologen ◽  
In The Wild ◽  
Partial Activity

The presence of nitrate is required for the induced synthesis of NADPH–nitrate reductase and its related partial activity Benzyl Viologen–nitrate reductase in a wild-type strain of Neurospora. In nit-3, a mutant lacking complete NADPH–nitrate reductase activity but retaining the partial activity Benzyl Viologen–nitrate reductase, the presence of nitrate ions is not required for the de-repressed synthesis of the latter enzyme. The accumulation of the capacity to synthesize nitrate reductase, and the related Benzyl Viologen–nitrate reductase, in the absence of protein synthesis does not require nitrate in the normal strain or in strain nit-3. Ammonia antagonizes the accumulation of this capacity in both strains. Nitrate is required for the synthesis of nitrate reductase and related activities from presumedly preformed mRNA in the wild-type strain. Nitrate is not required for the comparable function in strain nit-3. Ammonia appears to stop the synthesis of nitrate reductase and related activities from presumedly preformed mRNA in the wild-type strain and in strain nit-3. The effects of nitrate, or ammonia and of no nitrogen source on the induced synthesis of nitrate reductase cannot be explained on the basis of the effects of the different nitrogen sources on general synthesis of RNA or of protein.

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