Amino Acid Transport into Cultured Tobacco Cells

Harrington, Helen; Berry, Sandra L.; Henke, Randolph R.

doi:10.1104/pp.67.2.379

Cited by 47 publications

(37 citation statements)

References 29 publications

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“…The result suggests that uptake and efflux are mediated by the same system and, further, that both agents result in the loss, inactivation, or unavailability of sites needed for both uptake and efflux. The effect of cycloheximide is general in the sense that it also inhibits amino acid uptake in these cells (data not shown) and a variety of uptake systems in.tobacco cells (16). It is not clear whether this is a result of high turnover rates for proteins involved in higher plant uptake systems or some less specific effect of the drug.…”

Section: Discussionmentioning

confidence: 80%

Regulation of sulfate uptake in carrot cells: Properties of a hypercontrolled variant

Furner¹,

Sung²

1982

Proc. Natl. Acad. Sci. U.S.A.

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Sulfate uptake in haploid carrot cultures can be experimentally controlled by the sulfur source provided for growth. The rate of sulfate uptake is low in cells grown on cystine or sulfate and high in sulfur-starved cells. A selenate-resistant variant cell line has been isolated from a haploid carrot line. The variant shows hypersuppression of sulfate uptake by cystine and essentially normal control by the other treatments. While both lines efflux intracellular sulfate in the presence ofexternal sulfate, the rate of efflux from the variant is 4-6 times higher at comparable levels of initial -intracellular sulfate.-Further, properties of the efflux and uptake in both lines suggest that they are mediated by the same system. We propose that the variant possesses an altered uptake-efflux system -that is more readily reversed and more subject to control by some metabolite derived from cystine.Sulfate uptake has been studied in a variety of organisms, and permease-deficient mutants have been selected by resistance to sulfate analogs in Escherichia coli (1), yeast (2), Aspergillus (3), and Neurospora (4). In Aspergillus, a mutant showing hypersuppression of sulfate uptake by methionine has been isolated and was found to be allelic to other permease-less mutants (5). In general, the regulation of these permease activities has been attributed to repression by some reduced sulfur compound; however, there is also evidence for inhibition of uptake by some early intermediate in reduction (2).Tobacco cells (6) and potato tuber discs (7) show suppression of sulfate uptake if incubated with sulfur-containing amino acids. Using tobacco cells, Smith (8,9) found that sulfate uptake was suppressed by growth on cyst(e)ine or sulfate and, on the basis of correlative evidence, suggested that uptake was controlled by feedback inhibition by the intracellular sulfate pool.In this paper, we describe a variant carrot cell line that has altered control of sulfate uptake by cystine. The results show that this line has an altered uptake-efflux system and is impaired in sulfate reduction. The relationships among these phenotypes are discussed. MATERIALS AND METHODSCulture Methods and Variant Isolation. The parental cell line has been described (10), and growth in suspension culture was monitored turbidimetrically (11). Media used in this work were based on Gamborg's B5 medium (12), modified by replacing (NH4)2504 with NH4NO3 and other sulfates with equimolar chlorides. This medium, referred to as -S medium, was used unsupplemented or supplemented with cystine (Eastman). Suspension cultures of both lines were grown in 100 ml of medium in 500-ml flasks with continuous shaking at 120 rpm at 250C in the light. Plants were produced from both lines on B5 medium devoid of2,4-dichlorophenoxyacetic acid and callus was reinitiated from root tips on B5 medium supplemented with 2,4-dichlorophenoxyacetic acid at 1 mg/liter. Chromosome counts were done as described (10).The variant was isolated from the parental line, HA, by plating cells on -S medi...

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Section: Discussionmentioning

confidence: 80%

Regulation of sulfate uptake in carrot cells: Properties of a hypercontrolled variant

Furner¹,

Sung²

1982

Proc. Natl. Acad. Sci. U.S.A.

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“…vanced by Theologis (23) (21) and lysine uptake (10) in cultured cells, inhibition of Clnechanism (19), as well as ACT-D and CPN, two in-uptake by storage tissues from several species (6), inhibition of RNA synthesis (8).…”

Section: Resultsmentioning

confidence: 99%

Induced K⁺ Efflux from Cultured Rose Cells

Murphy¹

1988

Plant Physiol.

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Certain physical and biological stresses, including ultraviolet (UV-C and UV-B)2 light (14), Pseudomonas syringae cells (1), and Erwinia pectate lyase (2), induce an efflux of K+ from cultured plant cells. The significance of this efflux is not clear: it may be a symptom of damage that leads eventually to death of the cells; it may be a defensive reaction to the stress; or it may be an abnormal turning on of a normal efflux process. In the case of UV treatment, the efflux occurs sufficiently rapidly that it does not seem to be a result of death and disintegration of the cells (18). Information about the mechanism of the efflux might provide clues to its significance.There are several reasons to suspect that gene expression might be involved in the UV-induced efflux of K+, either in a positive or negative way. For one thing, the interaction of UV with nucleic acids is well known, and the inhibition of protein synthesis by UV in cultured tobacco cells has been described (15). One can hypothesize that this inhibition triggers changes in the plasma membrane that lead to the loss of K+.It is also reasonable to hypothesize that protein synthesis is required for the induction of the efflux. The start of K+ efflux from UV-treated, suspension-cultured rose cells follows the treatment by approximately 15 min (14), a period that could be required for the transcription and translation of genes. The induction of K+ effiux by UV is inhibited by CCCP (14) and anaerobiosis (A Huerta, personal communication), which suggests that metabolic energy is required; the need for energy could '

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“…Also the uptake of ions and organic solutes is decreased in Ca2+-depleted cells or tissues (4,7,15,20). However, the molecular mechanism for all these membrane associated phenomena is not clear (3 AIB (0.5 mCi/mmol) and further additions as indicated.…”

mentioning

confidence: 99%

“…In the past, an increased ion leakage of roots lacking proper Ca2" supply had been noticed (17) and an increased effiux of organic and inorganic substrates from various plant cells under such conditions has repeatedly been described (4,7,15). Also the uptake of ions and organic solutes is decreased in Ca2+-depleted cells or tissues (4,7,15,20).…”

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confidence: 99%

Effects of Ca²⁺ on Amino Acid Transport and Accumulation in Roots of Phaseolus vulgaris

Rickauer¹,

Tanner²

1986

Plant Physiol.

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Ca2" stimulates the uptake of a-aminoisobutyric acid (AIB) into excised or intact Phaseolus vulgaris L. roots by a factor of two. In roots depleted of Ca2" by preincubation with ethylenediaminetetraacetate, ethyleneglycol-bis(f6-aminoethyl ether)-NN'-tetraacetic acid, or streptomycin, the stimulatory effect is 7-to 10-fold. In the presence of Ca2", roots accumulate AIB more than 100-fold; Ca2"-depleted roots only equilibrate with AIB. Radioautography shows I`4C]AIB to be present in all cells after 90 min. Although Ca2"-depleted roots lose accumulated ['4C]AIB about 10 times faster than roots supplied with Ca2", this increased efflux is not the main cause for the decrease in net uptake observed. The latter is rather due to a less negative membrane potential A# in Ca2 depleted roots (-120 mV -. -50 such conditions has repeatedly been described (4,7,15). Also the uptake of ions and organic solutes is decreased in Ca2+-depleted cells or tissues (4,7,15,20). However, the molecular mechanism for all these membrane associated phenomena is not clear (3 AIB (0.5 mCi/mmol) and further additions as indicated. The flasks were shaken in a water bath at 28°C; 100 ,l aliquots of the medium were taken at various times, and the radioactivity was determined. After adding 5 ml of scintillation cocktail the samples were counted in a scintillation counter. At the end of the experiment roots were blotted dry on filter paper and fresh weight was determined. In some cases, the radioactivity in the roots was directly determined by adding 0.7 ml Tissue Solubilizer TS-1 to four root segments. After 24 h at room temperature, 10 ml of toluene cocktail were added and the samples counted. The uptake rates determined were the same with each method.Efflux Experiments. Forty root-tip segments were preloaded for 3 h with ['4C]AIB in the presence of 10 mM Ca2+ in the medium as described for uptake experiments. After the loading period roots were washed twice in 10 ml ice-cold K-phosphate (10 mm, pH 5.2) for 3 min and then transferred into Erlenmeyer flasks containing 5 ml 10 mm K-phosphate and further additions as indicated. Efflux of ['4C]AIB was determined by counting the radioactivity in 100 ,g aliquots withdrawn from the medium as described for uptake experiments. All uptake and efflux experiments were repeated at least three times.www.plantphysiol.org on May 9, 2018 -Published by Downloaded from

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Amino Acid Transport into Cultured Tobacco Cells

Cited by 47 publications

References 29 publications

Regulation of sulfate uptake in carrot cells: Properties of a hypercontrolled variant

Regulation of sulfate uptake in carrot cells: Properties of a hypercontrolled variant

Induced K⁺ Efflux from Cultured Rose Cells

Effects of Ca²⁺ on Amino Acid Transport and Accumulation in Roots of Phaseolus vulgaris

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Amino Acid Transport into Cultured Tobacco Cells

Cited by 47 publications

References 29 publications

Regulation of sulfate uptake in carrot cells: Properties of a hypercontrolled variant

Regulation of sulfate uptake in carrot cells: Properties of a hypercontrolled variant

Induced K+ Efflux from Cultured Rose Cells

Effects of Ca2+ on Amino Acid Transport and Accumulation in Roots of Phaseolus vulgaris

Contact Info

Product

Resources

About

Induced K⁺ Efflux from Cultured Rose Cells

Effects of Ca²⁺ on Amino Acid Transport and Accumulation in Roots of Phaseolus vulgaris