A mutant of Chlamydomonas reinhardtii altered in the transport of ammonium and methylammonium

Franco, A. R.; Cárdenas, Jacobo; Fernández, Emilio

doi:10.1007/bf00428880

Cited by 33 publications

(8 citation statements)

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“…Kinetic data for methylammonium/ammonium transporters from Chlamydomonas are consistent with those previously reported for vegetative and N‐starved cells (Franco et al. 1987).…”

Section: Discussionsupporting

confidence: 90%

“…3). Although kinetic data of vegetative and N‐starved cells are known (Franco et al. 1987), we have used these kinds of cells as a control because the data in pre‐gametes are unknown.…”

Section: Resultsmentioning

confidence: 99%

“…Uptake of [ 14 C]‐methylammonium was determined as described previously (Franco, Cárdenas & Fernández 1987). Cells were grown in TAP and resuspended to a final concentration of 15–20 µ g chlorophyll mL −1 culture in nitrogen‐free medium; [ 14 C]‐methylammonium was added to 2 mL of vegetative cells, pre‐gametes or gametes to final concentrations of 6, 8, 12.5, 25, 50 and 100 µ m , under continuous stirring immediately or after illumination of pre‐gametes.…”

Section: Methodsmentioning

confidence: 99%

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Regulation by light of ammonium transport systems in Chlamydomonas reinhardtii

Ermilova

Zalutskaya

Nikitin

et al. 2010

Plant Cell & Environment

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The unicellular green alga Chlamydomonas reinhardtii is able to take up methylammonium/ammonium from the medium at different stages of its sexual life cycle. Vegetative cells and pre-gametes mostly used a low-affinity system (LATS) component, but gametes obtained after light treatment of N-deprived pre-gametes expressed both LATS and high-affinity system (HATS) components for the uptake of methylammonium/ammonium. The activity of the LATS component was stimulated by light in only 5 min in a process independent of protein synthesis. By using the lrg6 mutant that produces sexually competent gametes in the dark, light effects on ammonium transport and gamete differentiation have been separately analysed. We have found light regulation of four Amt1 genes: Amt1; 1, Amt1; 2, Amt1; 4 and Amt1; 5. Whereas light-dependent expression of Amt1; 1, Amt1; 2 and Amt1; 4 was independent of gametogenesis, and that of Amt1; 5 was activated in the lrg6 mutant, suggesting a connection between this transporter and the subsequent events taking place during gametogenesis.

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“…Kinetic data for methylammonium/ammonium transporters from Chlamydomonas are consistent with those previously reported for vegetative and N‐starved cells (Franco et al. 1987).…”

Section: Discussionsupporting

confidence: 90%

“…3). Although kinetic data of vegetative and N‐starved cells are known (Franco et al. 1987), we have used these kinds of cells as a control because the data in pre‐gametes are unknown.…”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Regulation by light of ammonium transport systems in Chlamydomonas reinhardtii

Ermilova

Zalutskaya

Nikitin

et al. 2010

Plant Cell & Environment

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“…This suggested that there is sufficient expression of ammonium transporters during nitrate utilization so that the incremental addition of ammonium can be used for periodic reduction of pH [35]. This approach will thereby provide a means to implement the proposed stoichiometrically-balanced nitrogen feed (36 % N-NH 4 + and 64 % N-NO 3 - ).…”

Section: Resultsmentioning

confidence: 99%

Achieving pH control in microalgal cultures through fed-batch addition of stoichiometrically-balanced growth media

2013

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BackgroundLack of accounting for proton uptake and secretion has confounded interpretation of the stoichiometry of photosynthetic growth of algae. This is also problematic for achieving growth of microalgae to high cell concentrations which is necessary to improve productivity and the economic feasibility of commercial-scale chemical production systems. Since microalgae are capable of consuming both nitrate and ammonium, this represents an opportunity to balance culture pH based on a nitrogen feeding strategy that does not utilize gas-phase CO2 buffering. Stoichiometry suggests that approximately 36 weight%N-NH4+ (balance nitrogen as NO3-) would minimize the proton imbalance and permit high-density photoautotrophic growth as it does in higher plant tissue culture. However, algal media almost exclusively utilize nitrate, and ammonium is often viewed as ‘toxic’ to algae.ResultsThe microalgae Chlorella vulgaris and Chlamydomonas reinhardtii exclusively utilize ammonium when both ammonium and nitrate are provided during growth on excess CO2. The resulting proton imbalance from preferential ammonium utilization causes the pH to drop too low to sustain further growth when ammonium was only 9% of the total nitrogen (0.027 gN-NH4+/L). However, providing smaller amounts of ammonium sequentially in the presence of nitrate maintained the pH of a Chlorella vulgaris culture for improved growth on 0.3 gN/L to 5 gDW/L under 5% CO2 gas-phase supplementation. Bioreactor pH dynamics are shown to be predictable based on simple nitrogen assimilation as long as there is sufficient CO2 availability.ConclusionsThis work provides both a media formulation and a feeding strategy with a focus on nitrogen metabolism and regulation to support high-density algal culture without buffering. The instability in culture pH that is observed in microalgal cultures in the absence of buffers can be overcome through alternating utilization of ammonium and nitrate. Despite the highly regulated array of nitrogen transporters, providing a nitrogen source with a balanced degree of reduction minimizes pH fluctuations. Understanding and accommodating the behavior of nitrogen utilization in microalgae is key to avoiding ‘culture crash’ and reliance on gas phase CO2 buffering, which becomes both ineffective and cost-prohibitive for commercial-scale algal culture.

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“…In fungi, CH3 NH + and NH + uptake respond in a similar fashion to varying N conditions (Arst and Cove, 1969;Hackette et al, 1970;Pateman et al, 1974;Roon et al;1975); fungal mutants that are deficient in CH3NH + transport are also deficient in NH + transport (Arst and Page, 1973;Pateman et al, 1974;Roon et al, 1975). A single mutation in the unicellular alga Chlorella diminishes CH3NH + and NH4 + uptake, but not ethylammonium uptake (Franco et al, 1987).…”

Section: Introductionmentioning

confidence: 98%

Assessment of methylammonium as an analog for ammonium in plant uptake from soil

Jackson

Bloom

1994

Plant Soil

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We tested radioactive methylammonium (14CH3NI--I+) as a tracer for ammonium (NH +) in root uptake measurements from soil. Tomato (Lycopersicon esculentum Moll. cv T5) in 3 L pots filled with loamy sand soil received 40, 200, or 600 #mol 14CH3NH + or 15NH+. During a 4 h period, the plants absorbed laCH3NH + at slower rates than ~SNH +. Estimates ofNH4 + absorption based on 15NH+ absorption were 0.9-7.9/~mol NH4 + g-l plant dry weight h -l, whereas those based on IaCH3NH+ absorption were 0.2-1.0/~mol NH4 + g-i plant dry weight h -~. After 4 h, approximately one-half of the applied 15N was not recovered in the plants or soil KC1 extracts; apparently, this lSN was either immobilized or nitrified and denitrified by soil biota. By contrast, almost all the t4CH3NH+ remained in the soil solution after 4 h, but after a 10 d incubation, approximately 20% had been released as 14CO~_. These differences in plant absorption rates and movement through soil pools indicate that CH3NH + cannot be used reliably as an NH + analog in soil.

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A mutant of Chlamydomonas reinhardtii altered in the transport of ammonium and methylammonium

Abstract: On page 328, the last paragraph in the second column should read: The soybean haploid genome contains two classes of beta tubulin genes.

Cited by 33 publications

References 40 publications

Regulation by light of ammonium transport systems in Chlamydomonas reinhardtii

Regulation by light of ammonium transport systems in Chlamydomonas reinhardtii

Achieving pH control in microalgal cultures through fed-batch addition of stoichiometrically-balanced growth media

Assessment of methylammonium as an analog for ammonium in plant uptake from soil

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