Can Externally Applied Atp Supply Energy to Active Ion Uptake Mechanisms of Intact Plant Cells?

1974 ◽  
Vol 1 (2) ◽  
pp. 211 ◽  
Author(s):  
U Lüttge ◽  
EV Schöch ◽  
E Ball
Keyword(s):  
External Medium ◽  
Divalent Cations ◽  
Plant Cells ◽  
Bundle Sheath ◽  
Metabolic Inhibition ◽  
Ion Uptake ◽  
Intact Plant ◽  
K Uptake ◽  
Atp Supply ◽  
Uptake Mechanisms

ATP applied in the external medium of leaf slices and bundle-sheath preparations at concentrations between 1.0 and 2.5 mM apparently enhances K+ uptake. However, this effect depends on the presence of Ca2+ or Mg2+ in the medium. ATP is shown to release a Ca2+ or Mg2+ inhibition of K+ uptake. If the Ca2+ or Mg2+ content of the medium is varied and EDTA used to mimic the effect of ATP, it can be demonstrated that the observed effect of ATP is entirely explicable by its chelation of divalent cations. Externally applied ATP has similar relative effects on K+ uptake under control conditions and under conditions where metabolism is inhibited, and although it apparently fully releases metabolic inhibition, these experiments reveal ambiguities which are discussed. It is con- cluded that apparent effects of externally applied ATP may often be indirect. The possibility of specific, i.e. energy-providing, effects can nevertheless not be ruled out in principle, but more sophisti- cated experimentation than found hitherto in the literature is required to demonstrate such effects.

Properties of the mammalian and yeast metal-ion transporters DCT1 and Smf1p expressed in Xenopus laevis oocytes

2001 ◽  
Vol 204 (6) ◽  
pp. 1053-1061 ◽  
Author(s):  
A. Sacher ◽  
A. Cohen ◽  
N. Nelson
Keyword(s):  
Xenopus Laevis ◽  
Metal Ions ◽  
Metal Ion ◽  
Divalent Cations ◽  
Ion Uptake ◽  
Xenopus Laevis Oocytes ◽  
Ion Transporters ◽  
Divalent Metal Ions ◽  
Transport Pathway ◽  
Metal Ion Uptake

Transition metals are essential for many metabolic processes, and their homeostasis is crucial for life. Metal-ion transporters play a major role in maintaining the correct concentrations of the various metal ions in living cells. Little is known about the transport mechanism of metal ions by eukaryotic cells. Some insight has been gained from studies of the mammalian transporter DCT1 and the yeast transporter Smf1p by following the uptake of various metal ions and from electrophysiological experiments using Xenopus laevis oocytes injected with RNA copies (c-RNA) of the genes for these transporters. Both transporters catalyze the proton-dependent uptake of divalent cations accompanied by a ‘slippage’ phenomenon of different monovalent cations unique to each transporter. Here, we further characterize the transport activity of DCT1 and Smf1p, their substrate specificity and their transport properties. We observed that Zn(2+) is not transported through the membrane of Xenopus laevis oocytes by either transporter, even though it inhibits the transport of the other metal ions and enables protons to ‘slip’ through the DCT1 transporter. A special construct (Smf1p-s) was made to enhance Smf1p activity in oocytes to enable electrophysiological studies of Smf1p-s-expressing cells. 54Mn(2+) uptake by Smf1p-s was measured at various holding potentials. In the absence of Na(+) and at pH 5.5, metal-ion uptake was not affected by changes in negative holding potentials. Elevating the pH of the medium to 6.5 caused metal-ion uptake to be influenced by the holding potential: ion uptake increased when the potential was lowered. Na(+) inhibited metal-ion uptake in accordance with the elevation of the holding potential. A novel clutch mechanism of ion slippage that operates via continuously variable stoichiometry between the driving-force pathway (H(+)) and the transport pathway (divalent metal ions) is proposed. The possible physiological advantages of proton slippage through DCT1 and of Na(+) slippage through Smf1p are discussed.

A Comparison of Potassium and Chloride Uptake by Tradescantia albiflora Leaf Cells at Different KCI Concentrations

1975 ◽  
Vol 2 (4) ◽  
pp. 471
Author(s):  
C Johansen ◽  
U Luttge
Keyword(s):  
Oxidative Phosphorylation ◽  
Ion Uptake ◽  
Metabolic Inhibitors ◽  
K Uptake ◽  
Chloride Uptake ◽  
Cyclic Photophosphorylation

Light stimulates K+ and Cl- uptake into T. albiflora leaf slices from solutions through which N*2 is bubbled, and not from aerated solutions, at KCl concentrations of 0.5, 5 and 20 mM. The metabolic inhibitors CCCP, DCMU and oligomycin affect K+ and Cl- uptake similarly at each of these KCl concentrations. The results suggest that both K+ and Cl- uptake under all conditions studied are driven by energy derived from a cytoplasmic pool of ATP. In aerobic solutions in the light ATP can be supplied by either oxidative phosphorylation or photophosphorylation while in N*2-bubbled solutions in the light non-cyclic photophosphorylation and possibly oxidative phosphorylation, utilizing photosynthetically evolved O*2, provide ATP. As Cl- uptake appears to be independent of K+ uptake, it is suggested that ion uptake by T. albiflora leaf cells may occur according to a mechanism which has been proposed for other green cells, where K+ and CI- are thought to exchange for H+ and OH- respectively.

scholarly journals Carbon nanocarriers deliver siRNA to intact plant cells for efficient gene knockdown

2020 ◽  
Vol 6 (26) ◽  
pp. eaaz0495 ◽  
Author(s):  
Gozde S. Demirer ◽  
Huan Zhang ◽  
Natalie S. Goh ◽  
Rebecca L. Pinals ◽  
Roger Chang ◽  
...  
Keyword(s):  
Sirna Delivery ◽  
Control Plant ◽  
Plant Cells ◽  
Plant Biotechnology ◽  
Intact Plant ◽  
Intact Cells ◽  
Efficient Gene ◽  
Dna Vectors ◽  
And Control ◽  
Interfering Rna

Posttranscriptional gene silencing (PTGS) is a powerful tool to understand and control plant metabolic pathways, which is central to plant biotechnology. PTGS is commonly accomplished through delivery of small interfering RNA (siRNA) into cells. Standard plant siRNA delivery methods (Agrobacterium and viruses) involve coding siRNA into DNA vectors and are only tractable for certain plant species. Here, we develop a nanotube-based platform for direct delivery of siRNA and show high silencing efficiency in intact plant cells. We demonstrate that nanotubes successfully deliver siRNA and silence endogenous genes, owing to effective intracellular delivery and nanotube-induced protection of siRNA from nuclease degradation. This study establishes that nanotubes could enable a myriad of plant biotechnology applications that rely on RNA delivery to intact cells.

Accommodation of powdery mildew fungi in intact plant cells

2008 ◽  
Vol 165 (1) ◽  
pp. 5-18 ◽  
Author(s):  
Ruth Eichmann ◽  
Ralph Hückelhoven
Keyword(s):  
Powdery Mildew ◽  
Plant Cells ◽  
Intact Plant ◽  
Powdery Mildew Fungi

Ion Uptake and Protein Synthesis in Enzymatically Isolated Plant Cells

Nature ◽  
1965 ◽  
Vol 205 (4974) ◽  
pp. 921-922 ◽  
Author(s):  
W. H. JYUNG ◽  
S. H. WITTWER ◽  
M. J. BUKOVAC
Keyword(s):  
Protein Synthesis ◽  
Plant Cells ◽  
Ion Uptake

scholarly journals Photoinjection of fluorescent nanoparticles into intact plant cells using femtosecond laser amplifier

APL Photonics ◽  
2020 ◽  
Vol 5 (6) ◽  
pp. 066104
Author(s):  
Taufiq Indra Rukmana ◽  
Gabriela Moran ◽  
Rachel Méallet-Renault ◽  
Gilles Clavier ◽  
Tadashi Kunieda ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Plant Cells ◽  
Intact Plant ◽  
Fluorescent Nanoparticles ◽  
Laser Amplifier

Activation of furosemide-sensitive K+ fluxes in myocytes by ouabain and recovery from metabolic inhibition

1990 ◽  
Vol 259 (3) ◽  
pp. H962-H972 ◽  
Author(s):  
O. Kohmoto ◽  
J. A. Krueger ◽  
W. H. Barry
Keyword(s):  
Calcium Concentration ◽  
Metabolic Inhibition ◽  
Atp Depletion ◽  
Metabolic Inhibitors ◽  
Cell Shrinkage ◽  
K Uptake ◽  
Dependent Protein Kinase ◽  
K Channels ◽  
Ventricular Cells ◽  
Dependent Protein

Modulation of transsarcolemmal K+ flux mediated by the furosemide-sensitive K(+)-Cl- (or Na(+)-K(+)-Cl-) cotransport carrier was studied in cultured chick embryo ventricular cells. We defined at least three distinct K+ efflux pathways: 1) a Ba2(+)-sensitive efflux component, probably reflecting K+ movement through K+ channels; 2) a furosemide-sensitive component, reflecting K(+)-Cl- cotransport; and 3) a component insensitive to both Ba2+ and furosemide. With respect to K+ influx, there were 1) a ouabain-sensitive K+ uptake presumably mediated by Na(+)-K(+)-adenosinetriphosphatase and 2) a furosemide-sensitive K+ uptake. The effects of elevation of intracellular calcium concentration ([Ca2+]i) on Ba2+ and furosemide-sensitive K+ flux pathways were studied. Elevation of [Ca2+]i had minor effects on Ba2(+)-sensitive K+ flux. However, elevation of [Ca2+]i produced by exposure to ouabain for 60 min activated a furosemide-sensitive 42K+ efflux and a ouabain-resistant, furosemide-sensitive 42K+ influx. The activation of K+ influx, caused by an increase in [Ca2+]i, was completely inhibited by ATP depletion (produced by exposure to ouabain and metabolic inhibitors simultaneously) and was partially inhibited by the calmodulin inhibitor W7. Activation of the furosemide-sensitive K+ flux was also produced by washout of metabolic inhibitors, a condition in which ATP resynthesis occurs in the presence of an increased [Ca2+]i. Activation of furosemide-sensitive K+ fluxes by exposure to ouabain or washout of metabolic inhibitors caused a net K+ loss, which accounts in part for the cell shrinkage noted during recovery from metabolic inhibition in previous studies. These results suggest that [Ca2+]i and intracellular ATP concentration are important in the regulation of furosemide-sensitive K+ flux in these cells, perhaps via the involvement of a Ca2(+)-calmodulin-dependent protein kinase.

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