scholarly journals Chlortetracycline and the transmembrane potential of the inner membrane of plant mitochondria

1986 ◽  
Vol 237 (3) ◽  
pp. 765-771 ◽  
Author(s):  
I M Møller ◽  
C J Kay ◽  
J M Palmer
Keyword(s):  
Membrane Potential ◽  
Transmembrane Potential ◽  
Plant Mitochondria ◽  
Jerusalem Artichoke ◽  
Fold Increase ◽  
Nadh Oxidation ◽  
Helianthus Tuberosus ◽  
Succinate Oxidation ◽  
Bivalent Cations ◽  
Carbonyl Cyanide

The oxidation of NADH or succinate by Jerusalem-artichoke (Helianthus tuberosus L.) mitochondria in the presence of chlortetracycline induced an increase in chlortetracycline fluorescence. Any treatment that prevented the formation of a transmembrane potential (as monitored by changes in safranine absorbance, A511-A533), e.g. uncoupling with carbonyl cyanide p-trifluoromethoxyphenylhydrazone, inhibition of dehydrogenase activity or electron transport, anaerobiosis or depletion of substrate, prevented the increase in chlortetracycline fluorescence or caused it to disappear. Changes in chlortetracycline fluorescence were always slower than changes in the safranine absorbance. The increase in chlortetracycline fluorescence caused by succinate oxidation had an excitation maximum at 393 nm, indicating that a Ca2+-chlortetracycline complex was involved. The increase in fluorescence was observed even in the presence of EDTA, which removes all external bivalent cations, indicating that internal Ca2+ is mobilized. Although NADH and succinate oxidations gave the same membrane potential and qualitatively had the same effect on chlortetracycline fluorescence, NADH oxidation caused a much larger (over 3-fold) increase in chlortetracycline fluorescence than did succinate oxidation. It is possible that this is connected with the Ca2+-dependence of NADH oxidation. In the presence of 2 mM external Ca2+, chlortetracycline collapsed the transmembrane potential and uncoupled succinate and duroquinone oxidation.

scholarly journals A specific role for Ca2+ in the oxidation of exogenous NADH by Jerusalem-artichoke (Helianthus tuberosus) mitochondria

1981 ◽  
Vol 194 (2) ◽  
pp. 487-495 ◽  
Author(s):  
I M Møller ◽  
S P Johnston ◽  
J M Palmer
Keyword(s):  
Jerusalem Artichoke ◽  
Relative Effect ◽  
Specific Role ◽  
Nadh Oxidation ◽  
Helianthus Tuberosus ◽  
Bivalent Metal ◽  
Fixed Charges ◽  
Bivalent Cations ◽  
Bivalent Ions ◽  
Bivalent Metal Ions

1. The addition of chelators to a suspension of mitochondria in a low-cation medium containing 9-aminoacridine caused a decrease in 9-aminoacridine fluorescence. The chelators removed bivalent cations from the membranes and allowed more 9-aminoacridine to move into the diffuse layer. The relative effect of EGTA and EDTA on the fluorescence suggested that the mitochondria are isolated with about equal amounts of Ca2+ and Mg2+ on the membranes. 2. The removal of the bivalent ions by chelators resulted in the inhibition of NADH oxidation. The inhibition could not be removed by adding sufficient decamethylenebistrimethylammonium ion (DM2+) to screen the fixed charges on the membranes and restore the fluorescence of 9-aminoacridine. This observation suggests that bivalent metal ions have a specific role in the oxidation of NADH. 3. Ca2+ and not Mg2+ reversed the inhibition of NADH oxidation caused by EGTA, whereas both reversed the inhibition caused by EDTA. This suggests that Ca2+ plays a specific role and that Mg2+ reverses the inhibition caused by EDTA by displacing the bound calcium from the chelator. 4. The results are interpreted as showing that Ca2+ plays a specific role in the oxidation of external NADH in addition to its ability to screen electrostatically or bind to the fixed charges associated with the surface of the membrane.

scholarly journals 9-Aminoacridine as a fluorescent probe of the electrical diffuse layer associated with the membranes of plant mitochondria

1981 ◽  
Vol 193 (1) ◽  
pp. 37-46 ◽  
Author(s):  
I M Møller ◽  
W S Chow ◽  
J M Palmer ◽  
J Barber
Keyword(s):  
Fluorescent Probe ◽  
Plant Mitochondria ◽  
Jerusalem Artichoke ◽  
Diffuse Layer ◽  
Helianthus Tuberosus ◽  
Equal Concentration ◽  
Charge Screening ◽  
Arum Maculatum ◽  
Theoretical Considerations

1. Mitochondria from Jerusalem artichoke (Helianthus tuberosus) tubers and Arum maculatum spadices caused a quenching of the fluorescence of 9-aminoacridine when mixed in a low-cation medium (approximately 1 mM-K+) and addition of chelators further decreased the fluorescence. Salts released the quenching of the 9-aminoacridine fluorescence and the efficiency of the release appeared to be mainly dependent on the valency of the cation (C3+ greater than C2+ greater than C+). 2. The results are consistent with the theory of charge screening and demonstrate that 9-aminoacridine is a convenient probe of the behaviour of cations on the membranes of mitochondria and in the diffuse layer associated with these membranes. 3. The concentration of salt required to achieve half-maximal release of quenching of 9-aminoacridine fluorescence was proportional to the concentration of mitochondria in the solution and theoretical considerations show this effect to be inherent in the Gouy-Chapman theory. 4. 9-Aminoacridine was removed from the bulk of the solution by the mitochondria to a far greater extent than was Na+ or K+, which is suggested to be due to the formation of bi- and poly-valent cations by aggregation of 9-aminoacridine molecules in the diffuse layer. This would have implications for the use of 9-aminoacridine to determine delta pH across membranes. 5. Jerusalem-artichoke mitochondria removed from 9-aminoacridine and Ca2+ from the bulk of the solution and required more ions to screen the membranes than did an equal concentration (mg of protein/ml) of Arum mitochondria, indicating that Jerusalem-artichoke mitochondria contain more negative charges per mg of protein.

scholarly journals The activation of non-phosphorylating electron transport by adenine nucleotides in Jerusalem-artichoke (Helianthus tuberosus) mitochondria

1975 ◽  
Vol 152 (3) ◽  
pp. 637-645 ◽  
Author(s):  
R Sotthibandhu ◽  
J M Palmer
Keyword(s):  
Cytochrome B ◽  
Redox State ◽  
Nadh Dehydrogenase ◽  
Adenine Nucleotides ◽  
Plant Mitochondria ◽  
Jerusalem Artichoke ◽  
Simultaneous Oxidation ◽  
Carbonyl Cyanide ◽  
Bongkrekic Acid ◽  
Complex Manner

In isolated plant mitochondria the oxidation of both succinate and exogenous NADH responded in the expected manner to the addition of ADP or uncoupling agents, and the uncoupled rate of respiration was often in excess of the rate obtained in the presence of ADP. However, the oxidation of NAD+-linked substrates responded in a much more complex manner to the addition of ADP or uncoupling agents such as carbonyl cyanide p-trifluoromethoxyphenylhydrazone to mitochondria oxidizing pyruvate plus malate failed to result in a reliable stimulation; this uncoupled rate could be stimulated by adding AMP or ADP in the presence of oligomycin or bongkrekic acid. Spectrophometric measurements showed that the addition of AMP or ADP resulted in the simultaneous oxidation of endogenous nicotinamide nucleotide and the reduction of cytochrome b. ADP was only effective in bringing about these changes in redox state in the presence of Mg2+ whereas AMP did not require Mg2+. It was concluded that AMP activated the flow of electrons from endogenous nicotinamide nucleotide to cytochrome b, possible at the level of the internal NADH dehydrogenase.

scholarly journals VARIABILTY AND STABILTY OF TUBER YIELD OF JERUSALEM ARTICHOKE (Helianthus tuberosus L.) / VARIABILIDAD Y ESTABILIDAD DEL RENDIMIENTO DE TUBERCULOS DEL TOPINAMBO / VARIABILITÉ ET STABILITÉ DU RENDEMENT DU TUBERCULE DE TOPINAMBUR

Helia ◽  
2001 ◽  
Vol 24 (35) ◽  
pp. 25-32 ◽  
Author(s):  
Janoš Berenji ◽  
Vladimir Sikora
Keyword(s):  
Tuber Yield ◽  
Jerusalem Artichoke ◽  
Tuber Size ◽  
Yield Stability ◽  
Tuber Number ◽  
High Yield ◽  
Helianthus Tuberosus ◽  
Variety Trial ◽  
Stable Performance ◽  
The Stability

SUMMARYThe objective of this paper was to estimate the genetic and ecological variation as well as the stability of tuber yield per plant, tuber number per plant and tuber size of Jerusalem artichoke based on the results of a variety trial carried out with 20 different Jerusalem artichoke varieties during the period of 1994-2000. Significant genetic as well as ecologycal variation was observed for all of the traits studied. The most promissing varieties showing high tuber yield combined with high yield stability were “BT-4”, “Violet Rennes” and “UKR 4/ 82”. It is encouraging that the highest yielding varieties exibited a rather stable performance over environments.

Regulation of intracellular calcium in N1E-115 neuroblastoma cells: the role of Na+/Ca2+exchange

2002 ◽  
Vol 282 (5) ◽  
pp. C1000-C1008 ◽  
Author(s):  
Kara L. Kopper ◽  
Joseph S. Adorante
Keyword(s):  
Membrane Potential ◽  
Intracellular Calcium ◽  
Normal Cell ◽  
Buffer Capacity ◽  
Neuroblastoma Cells ◽  
Fold Increase ◽  
Scorpion Venom ◽  
Reverse Mode ◽  
Intracellular Ca

In fura 2-loaded N1E-115 cells, regulation of intracellular Ca2+ concentration ([Ca2+]i) following a Ca2+ load induced by 1 μM thapsigargin and 10 μM carbonylcyanide p-trifluoromethyoxyphenylhydrazone (FCCP) was Na+ dependent and inhibited by 5 mM Ni2+. In cells with normal intracellular Na+ concentration ([Na+]i), removal of bath Na+, which should result in reversal of Na+/Ca2+exchange, did not increase [Ca2+]i unless cell Ca2+ buffer capacity was reduced. When N1E-115 cells were Na+ loaded using 100 μM veratridine and 4 μg/ml scorpion venom, the rate of the reverse mode of the Na+/Ca2+ exchanger was apparently enhanced, since an ∼4- to 6-fold increase in [Ca2+]ioccurred despite normal cell Ca2+ buffering. In SBFI-loaded cells, we were able to demonstrate forward operation of the Na+/Ca2+ exchanger (net efflux of Ca2+) by observing increases (∼ 6 mM) in [Na+]i. These Ni2+ (5 mM)-inhibited increases in [Na+]i could only be observed when a continuous ionomycin-induced influx of Ca2+ occurred. The voltage-sensitive dye bis-(1,3-diethylthiobarbituric acid) trimethine oxonol was used to measure changes in membrane potential. Ionomycin (1 μM) depolarized N1E-115 cells (∼25 mV). This depolarization was Na+dependent and blocked by 5 mM Ni2+ and 250–500 μM benzamil. These data provide evidence for the presence of an electrogenic Na+/Ca2+ exchanger that is capable of regulating [Ca2+]i after release of Ca2+ from cell stores.

Sign in / Sign up

Export Citation Format

Share Document