Ammonia translocation in cyanobacteria

Boussiba, Samy

doi:10.1016/0168-6445(91)90002-y

Cited by 18 publications

(18 citation statements)

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“…The similarity of K m values for methylamine uptake (0.18 mM) by P. involutus isolate 01 (Table 1) and the K i value for the inhibition of methylamine uptake by ammonium (0.16 mM, Fig. 3) indicates that methylamine can be used as an analogue to study ammonium uptake, as showm in previous studies [10–13,23]. Methylamine provides two potential advantages over NH 4 + : it is not metabolised by the cells [28], avoiding interference between metabolism and transport in uptake experiments, and uptake experiments can be carried out over short periods during which efflux is considered to be negligible.…”

Section: Resultssupporting

confidence: 57%

“…However, the rates of diffusion do not seem to be sufficient to account for the requirements for plant growth [7]. In contradiction to this hypothesis, recent experiments with cyanobacteria, higher plants, yeasts and seaweeds [10–14] support the conclusion that specific systems for NH 4 + transport exist.…”

Section: Introductionmentioning

confidence: 95%

“…The aims of the present study were (1) to define the kinetics and energetics of ammonium transport in the ectomycorrhizal fungus Paxillus involutus and ectomycorrhizas and (2) to study the regulation of ammonium transport when the fungus was grown under various nitrogen regimes. Ammonium uptake was estimated by using its analogue tracer methylamine ([ 14 C]CH 3 NH 3 + ), as previously described [10–14].…”

Section: Introductionmentioning

confidence: 99%

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Ammonium and methylamine transport by the ectomycorrhizal fungus Paxillus involutus and ectomycorrhizas

Javelle¹,

Chalot²,

Söderström

et al. 1999

FEMS Microbiology Ecology

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Using [(14)C]methylamine as an analogue of ammonium, the kinetics and the energetics of NH(4)(+) transport were studied in the ectomycorrhizal fungus, Paxillus involutus (Batsch) Fr. The apparent half-saturation constant (K(m)) and the maximum uptake rate (V(max)) for the carrier-mediated transport derived from the Eadie-Hofstee transformation were 180 µM and 380 nmol (mg dry wt)(-1) min(-1,) respectively. Both pH dependence and inhibition by protonophores indicate that methylamine transport in P. involutus was dependent on the electrochemical H(+) gradient. Both long-term and short-term uptake experiments were consistent with regulation of ammonium/methylamine transport processes by the presence of an organic nitrogen source. Analysis of methylamine uptake by different P. involutus isolates revealed no obvious trend in the uptake capacities in relation to N deposition at the collection site. Kinetic parameters were determined in P. involutus/Betula pendula (Roth.) axenic association and in detached mycorrhizal roots isolated from forest sites. Enhanced methylamine uptake in the presence of the fungal symbiont was demonstrated. Homogeneous V(max) values were found for axenic and detached mycorrhizas, whereas K(m) values showed greater variations.

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Section: Resultssupporting

confidence: 57%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Ammonium and methylamine transport by the ectomycorrhizal fungus Paxillus involutus and ectomycorrhizas

Javelle¹,

Chalot²,

Söderström

et al. 1999

FEMS Microbiology Ecology

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“…The TAN concentrations in the microcosms is likely to be the result of the complex interaction between several processes, including excretion of ammonia by the metazoan consumers [ 39 ], and PM-mediated processes such as assimilatory nitrate reduction and dinitrogen fixation by diazotrophic cyanobacteria (including PCC 7120#11). Since ammonia is preferentially used as an inorganic nitrogen sources by many algae and most cyanobacteria [ 40 , 41 ], dissolved ammonia would be taken up by PMs and there would be significant intracellular ammonia pools in the PMs [ 41 ].…”

Section: Discussionmentioning

confidence: 99%

“…There are two ways that the ammonia could be released by PMs: during growth or due to damage or lysis of cells. Cyanobacteria, and in particular Anabaena spp., have been shown to release ammonia (NH 3 ), both in the presence and absence of nitrate in the medium, during different growth phases [ 40 ]. Since the ammonia spike (days 11 and 14) in the PCC 7120#11 microcosms corresponds with the rapid decrease in PCC 7120#11 cells between days 7 and 14, we postulate that the ammonia spike is primarily due to the release of ammonia from PCC 7120#11 cells due to “sloppy feeding” by invertebrate grazers.…”

Section: Discussionmentioning

confidence: 99%

The persistence and ecological impacts of a cyanobacterium genetically engineered to express mosquitocidal Bacillus thuringiensis toxins

Ketseoglou

Bouwer

2016

Parasites Vectors

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BackgroundThe cyanobacterium Anabaena PCC 7120#11 has been genetically engineered to act as a delivery vehicle for Bacillus thuringiensis subspecies israelensis mosquitocidal toxins. To address ecological concerns about releasing this genetically engineered microorganism into the environment for mosquito larva control, the persistence and ecological impacts of PCC 7120#11 was evaluated using multi-species, standardized aquatic microcosms.MethodsThe microcosms were set up as described in ASTM E1366-02 (Standard Practice for Standardized Aquatic Microcosms: Fresh Water), with a few modifications. The treatment group microcosms were inoculated with PCC 7120#11 and key water quality parameters and non-target effects were compared between the treatment and control groups over a period of 35 days.ResultsPCC 7120#11 decreased from a concentration of 4.50 × 106 cells/ml (at inoculation) to 1.32 × 103 cells/ml after 4 weeks and larvicidal activity against third instar larvae of Anopheles arabiensis was only evident for two weeks after treatment. Both treatment and the interaction of treatment and time had a significant effect on nitrate, phosphate and photosynthetic microorganism concentrations. Treatment with PCC 7120#11 caused a temporary spike in ammonia in the microcosms a week after treatment, but the concentrations were well below acute and chronic criteria values for ammonia in freshwater ecosystems. Cyprinotus vidua concentrations were not significantly different between PCC 7120#11 and control microcosms. In PCC 7120#11 microcosms, Daphnia pulex concentrations were significantly lower than control concentrations between days 18 and 25. By the end of the experiment, none of the measured variables were significantly different between the treatment groups.ConclusionsThe standard aquatic microcosm experiments provided more data on the ecological impacts of PCC 7120#11 than single-organism assessments would have. On the basis of the relatively minor, short-term effects that PCC 7120#11 had on water quality parameters and non-target invertebrates, further evaluation of PCC 7120#11 for use in integrated vector management is warranted.

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Regulation of Carbon and Nitrogen Metabolism in the Unicellular Cyanobacteria Synechococcus spp.

Marsac

Lee

1999

The Phototrophic Prokaryotes

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Ammonia translocation in cyanobacteria

Cited by 18 publications

References 0 publications

Ammonium and methylamine transport by the ectomycorrhizal fungus Paxillus involutus and ectomycorrhizas

Ammonium and methylamine transport by the ectomycorrhizal fungus Paxillus involutus and ectomycorrhizas

The persistence and ecological impacts of a cyanobacterium genetically engineered to express mosquitocidal Bacillus thuringiensis toxins

Regulation of Carbon and Nitrogen Metabolism in the Unicellular Cyanobacteria Synechococcus spp.

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