Maintenance of Photophosphorylation Despite Inhibition of the Transthylakoid pH Gradient by Tetracaine

1992 ◽  
Vol 47 (9-10) ◽  
pp. 717-725 ◽  
Author(s):  
Henrik Laasch
Keyword(s):  
Salt Concentration ◽  
Spinacia Oleracea ◽  
Electron Flow ◽  
Energy Coupling ◽  
Ph Gradient ◽  
Proton Pumps ◽  
Linear Electron ◽  
Ps Ii ◽  
Spinacia Oleracea L ◽  
Low Salt

The inhibition of the transthylakoid pH gradient, ΔpH, and of photophosphorylation by the local anesthetic tetracaine was investigated with isolated chloroplasts from Spinacia oleracea L. Tetracaine strongly inhibited ΔpH in the presence of low salt concentrations. In the presence of high salt concentrations, the inhibition of ΔpH was much smaller. This effect of salt concentration was observed only when both, cation and anion were easily membrane permeable. It was concluded that the effect of salts on ΔpH inhibition was excerted on the inside of the thylakoid membrane. The rate of photophosphorylation, Vp, driven by the PS Idependent artificial proton carrier phenazine methosulfate decreased with ΔpH in the presence of both, high and low salt concentrations. In contrast, Vp driven by the endogenous proton pumps of PS II + I-dependent linear electron flow was largely independent of ΔpH changes in the presence of low salt concentration. It appeared that energy coupling during linear electron transport, in contrast to artificially produced PS I-dependent coupling, may be localized to membrane-bound proton domains which are not accessible to the employed indicators of ΔpH. The data were discussed with respect to recent hypotheses on localized energy coupling in chloroplasts.

scholarly journals Efficient Heat Dissipation and Cyclic Electron Flow Confer Daily Air Exposure Tolerance in the Intertidal Seagrass Halophila beccarii Asch

2020 ◽  
Vol 11 ◽  
Author(s):  
Yang Fang ◽  
Zhijian Jiang ◽  
Chunyu Zhao ◽  
Linglan Li ◽  
Chanaka Isuranga Premarathne Maha Ranvilage ◽  
...  
Keyword(s):  
Electron Transport ◽  
Heat Dissipation ◽  
Electron Flow ◽  
Photochemical Quenching ◽  
Linear Electron ◽  
Carbon Utilization ◽  
Mesophyll Cells ◽  
Air Exposure ◽  
Ps Ii ◽  
Intertidal Seagrass

Seagrasses inhabiting the intertidal zone experience periodically repeated cycles of air exposure and rehydration. However, little is known about the photoprotective mechanisms in photosystem (PS)II and PSI, as well as changes in carbon utilization upon air exposure. The photoprotective processes upon air exposure in Halophila beccarii Asch., an endangered seagrass species, were examined using the Dual-PAM-100 and non-invasive micro-test technology. The results showed that air exposure enhanced non-photochemical quenching (NPQ) in both PSII and PSI, with a maximum increase in NPQ and Y(ND) (which represents the fraction of overall P700 that is oxidized in a given state) of 23 and 57%, respectively, resulting in intensive thermal energy dissipation of excess optical energy. Moreover, cyclic electron transport driven by PSI (CEF) was upregulated, reflected by a 50 and 22% increase in CEF and maximum electron transport rate in PSI to compensate for the abolished linear electron transport with significant decreases in pmfLEF (the proton motive force [pmf]) attributable solely to proton translocation by linear electron flow [LEF]). Additionally, H+ fluxes in mesophyll cells decreased steadily with increased air exposure time, exhibiting a maximum decrease of six-fold, indicating air exposure modified carbon utilization by decreasing the proton pump influxes. These findings indicate that efficient heat dissipation and CEF confer daily air exposure tolerance to the intertidal seagrass H. beccarii and provide new insights into the photoprotective mechanisms of intertidal seagrasses. This study also helps explain the extensive distribution of H. beccarii in intertidal zones.

Significance of Photosystem II Core Phosphorylation Heterogeneity for the Herbicide-Binding Domain

1993 ◽  
Vol 48 (3-4) ◽  
pp. 241-245 ◽  
Author(s):  
Maria Teresa Giardi
Keyword(s):  
Photosystem Ii ◽  
Spinacia Oleracea ◽  
Binding Activity ◽  
Alternative Methods ◽  
Relative Distribution ◽  
Ps Ii ◽  
Spinacia Oleracea L ◽  
Herbicide Binding ◽  
Ps Ii Core

Abstract In recent papers the heterogeneous nature of photosystem (PS) II core phosphorylation has been revealed (Giardi et al., BBRC 176, 1298 -1305 (1991); Plant Physiol. 100, 1948 -1954 (1992)). In this paper the action of endogenous and exogenous phosphatases both on the distribution of phosphorylated PS II core populations and on herbicide-binding activity in photosystem II preparations from Spinacia oleracea L. has been investigated. The results indicate that these phosphatases modify the photosystem II core phosphorylation heterogeneity at a different level. Dark incubation causes a partial dephosphorylation of D1 and D2 proteins by endogenous phosphatase(s) and changes the relative distribution of phosphorylated photosystem II core populations, while the action of the alkaline phosphatase leads to extensive dephosphorylation and to the detachment of PsbH protein from the photosystem II core. Dephosphorylation by the two alternative methods results in a differential modification of herbicide-binding activity. It is suggested that photosystem II heterogeneity with respect to the herbicide action, observed in vivo, could be a consequence of PS II core phosphorylation heterogeneity.

Synthesis and conformation of sequential basic polypeptides with branched and linear side chains

1985 ◽  
Vol 50 (12) ◽  
pp. 2925-2936 ◽  
Author(s):  
Štěpánka Štokrová ◽  
Jan Pospíšek ◽  
Jaroslav Šponar ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Salt Concentration ◽  
Salt Solution ◽  
Theoretical Work ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Cd Spectra ◽  
Low Salt ◽  
Conformational Freedom ◽  
Basic Polypeptides

Polypeptides (Lys-X-Ala)n and (Lys-X-Gly)n in which X represents residues of isoleucine and norleucine, respectively, and polypeptide (Tle-Lys-Ala)n, were synthesized via polymerization of 1-hydroxysuccinimidyl esters of the appropriate tripeptides to complete previously studied series. Circular dichroism (CD) spectra of the respective polymers were measured as a function of pH and salt concentration of the medium. The results were correlated with those obtained previously with the same series containing different amino acid residues at the X-position. The helix forming ability of the polypeptides (Lys-X-Ala)n with linear X side chain was found to be independent of the length. In the series (Lys-X-Gly)n the unordered conformation was the most probable one except (Lys-Ile-Gly)n. This polymer assumed the β conformation even in low salt solution at neutral pH. An agreement with some theoretical work concerned with the restriction of conformational freedom of amino acid residue branching at Cβ atom with our experimental results is evident.

Versuche zur präparativen Isolierung pflanzlicher Zellorganellen mittels der trägerfreien, kontinuierlichen Ablenkungselektrophorese

1964 ◽  
Vol 19 (11) ◽  
pp. 1072-1075 ◽  
Author(s):  
K. Hannig ◽  
W. Klofat ◽  
H. Endres
Keyword(s):  
Spinacia Oleracea ◽  
Taraxacum Officinale ◽  
Wird Eine ◽  
Spinacia Oleracea L ◽  
Helianthus Annus

Es wird eine präparative Methode zur Isolierung pflanzlicher Zellbestandteile mittels der trägerfreien, kontinuierlichen Ablenkungselektrophorese nach HANNIG 1, 2 kurz skizziert. Als Versuchsmaterial dienen Blätter von Spinat (Spinacia oleracea L.), Sonnenblumen (Helianthus annus L.) und Löwenzahn (Taraxacum officinale Web.).Die Verteilungskurven werden durch Extinktionsmessung der einzelnen Fraktionen in den Auffanggläschen erhalten. Die Definition der Teilchen erfolgt vorläufig morphologisch durch Anfärben und lichtmikroskopische Prüfung als auch durch elektronenmikroskopische Kontrolle nach vorheriger Präparation nach dem „negativ staining“ Verfahren 3,4 oder Kontrastierung mit Phosphorwolframsäure.Bei der Trennung werden Zellkerne und Zellkernfragmente, ganze Chloroplasten, „Mitochondrien“ und plasmatische Strukturen erhalten.

scholarly journals A review on the genetic resources, domestication and breeding history of spinach (Spinacia oleracea L.)

Euphytica ◽  
2020 ◽  
Vol 216 (3) ◽  
Author(s):  
Arnau Ribera ◽  
Yuling Bai ◽  
Anne-Marie A. Wolters ◽  
Rob van Treuren ◽  
Chris Kik
Keyword(s):  
Genetic Resources ◽  
Spinacia Oleracea ◽  
Spinacia Oleracea L ◽  
History Of ◽  
Breeding History
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