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921.
922.
Genetic implications of phylogeographical patterns in the conservation of the boreal wetland butterfly Colias palaeno (Pieridae)
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Katja Kramp Oldrich Cizek Pedro M. Madeira Ana A. Ramos Martin Konvicka Rita Castilho Thomas Schmitt 《Biological journal of the Linnean Society. Linnean Society of London》2016,119(4):1068-1081
The boreo‐montane wetland butterfly species Colias palaeno has a European distribution from the Alps to northern Fennoscandia. Within its European range, the species’ populations have shrunk dramatically in recent historical times. Therefore, detailed baseline knowledge of the genetic makeup of the species is pivotal in planning potential conservation strategies. We collected 523 individuals from 21 populations across the entire European range and analyzed nuclear (20 allozyme loci) and mitochondrial (600 bp of the cytochrome c oxidase subunit I gene) genetic markers. The markers revealed contrasting levels of genetic diversity and divergence: higher in allozymes and lower in mitochondrial sequences. Five main groups were identified by allozymes: Alps, two Czech groups, Baltic countries, Fennoscandia, and Poland. The haplotype mitochondrial network indicates a recent range expansion. The most parsimonious interpretation for our results is the existence of a continuous Würm glacial distribution in Central Europe, with secondary disjunction during the Last Glacial Maximum into a south‐western and a north‐eastern fragment and subsequent moderate differentiation. Both groups present signs of postglacial intermixing in the Czech Republic. However, even a complete extinction in this region would not considerably affect the species’ genetic basis, as long as the source populations in the Alps and in northern Europe, comprising the most relevant evolutionary units for conservation, are surviving. 相似文献
923.
Revisiting Kadenbach: Electron flux rate through cytochrome c‐oxidase determines the ATP‐inhibitory effect and subsequent production of ROS
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Sebastian Vogt Annika Rhiel Petra Weber Rabia Ramzan 《BioEssays : news and reviews in molecular, cellular and developmental biology》2016,38(6):556-567
Mitochondrial respiration is the predominant source of ATP. Excessive rates of electron transport cause a higher production of harmful reactive oxygen species (ROS). There are two regulatory mechanisms known. The first, according to Mitchel, is dependent on the mitochondrial membrane potential that drives ATP synthase for ATP production, and the second, the Kadenbach mechanism, is focussed on the binding of ATP to Cytochrome c Oxidase (CytOx) at high ATP/ADP ratios, which results in an allosteric conformational change to CytOx, causing inhibition. In times of stress, ATP‐dependent inhibition is switched off and the activity of CytOx is exclusively determined by the membrane potential, leading to an increase in ROS production. The second mechanism for respiratory control depends on the quantity of electron transfer to the Heme aa3 of CytOx. When ATP is bound to CytOx the enzyme is inhibited, and ROS formation is decreased, although the mitochondrial membrane potential is increased. 相似文献
924.
Ximenes VF Kanegae MP Rissato SR Galhiane MS 《Archives of biochemistry and biophysics》2007,457(2):134-141
Apocynin has been used as an efficient inhibitor of the NADPH oxidase complex and its mechanism of inhibition is linked to prior activation through the action of peroxidases. Here we studied the oxidation of apocynin catalyzed by myeloperoxidase (MPO) and activated neutrophils. We found that apocynin is easily oxidized by MPO/H2O2 or activated neutrophils and has as products dimer and trimer derivatives. Since apocynin impedes the migration of the cytosolic component p47phox to the membrane and this effect could be related to its conjugation with essential thiol groups, we studied the reactivity of apocynin and its MPO-catalyzed oxidation products with glutathione (GSH). We found that apocynin and its oxidation products do not react with GSH. However, this thiol compound was efficiently oxidized by the apocynin radical during the MPO-catalyzed oxidation. We suggest that the reactivity of apocynin radical with thiol compounds could be involved in the inhibitory effect of this methoxy-catechol on NADPH oxidase complex. 相似文献
925.
The powerful technique of energy diagrams has been used to analyze the mechanism for proton pumping in cytochrome c oxidase. Energy levels and barriers are derived starting out from recent kinetic experiments for the O to E transition, and are then refined using general criteria and a few additional experimental facts. Both allowed and non-allowed pathways are obtained in this way. A useful requirement is that the forward and backward rate should approach each other for the full membrane gradient. A key finding is that an electron on heme a (or the binuclear center) must have a significant lowering effect on the barrier for proton uptake, in order to prevent backflow from the pump-site to the N-side. While there is no structural gating in the present mechanism, there is thus an electronic gating provided by the electron on heme a. A quantitative analysis of the energy levels in the diagrams, leads to Prop-A of heme a3 as the most likely position for the pump-site, and the Glu278 region as the place for the transition state for proton uptake. Variations of key redox potentials and pKa values during the pumping process are derived for comparison to experiments. 相似文献
926.
Corcelli A Lobasso S Palese LL Saponetti MS Papa S 《Biochemical and biophysical research communications》2007,354(3):795-801
Membranes having an a high content of cardiolipin were isolated from an extremely halophilic archaeon Halorubrum sp. Absorbance difference spectra of detergent-solubilized plasma membranes reduced by dithionite suggested the presence of b-type cytochromes. Non-denaturing gel electrophoresis revealed only one fraction having TMPD-oxidase activity in which cardiolipin was the major lipid component. The electroeluted fraction showed a cytochrome c oxidase activity characterized by the reduced minus oxidized difference spectra as a terminal heme-copper oxidase. The cytochrome c oxidase activity of the archaeal cardiolipin-rich membranes was inhibited by the cardiolipin-specific fluorescent marker 10-N-nonyl acridine orange (NAO) in a dose-dependent manner. The results indicate that an archaeal analogue of cardiolipin is tightly associated to archaeal terminal oxidases and is required for its optimal functioning. 相似文献
927.
Peter Irwin Janine Brouillette Markus Germann Kevin Hicks Michael Kurantz William Damert 《Enzyme and microbial technology》1999,24(10):171-686
A method for estimating immobilized enzyme reaction progress curves, using simultaneous non-linear regression analysis of 2–3 substrate concentrations with time, is presented. These facile procedures involve using nested Gauss–Newton curve fitting algorithms on a Microsoft EXCEL spreadsheet. We refer to our technique as "nested" because the analysis consists of two or three mutually parameter-dependent sets of computations associated with bi- or termolecular enzyme-catalyzed reactions, respectively. We have applied the method to immobilized glucose oxidase-catalyzed reactions ([
-glucose] and [O2] with time) and found that the kinetic parameters from initial velocity data were similar to those determined by the nested curve fitting method discussed herein. 相似文献
928.
Maria Laurenzi Giuseppina Rea Rodolfo Federico Paraskevi Tavladoraki Riccardo Angelini 《Planta》1999,208(2):146-154
929.
Programme of senescence in petals and carpels of Pisum sativum L. flowers and its control by ethylene 总被引:3,自引:0,他引:3
The role of ethylene in the control of senescence of both petals and unpollinated carpels of pea was investigated. An increase
in ethylene production accompanied senescence, and the inhibitors of ethylene action were effective in delaying senescence
symptoms in different flower verticils. Pollination did not seem to trigger the senescence syndrome in the corolla as deduced
from the observation that petals from pollinated and unpollinated flowers and from flowers whose carpels had been removed
senesced at the same time. A cDNA clone encoding a putative ethylene-response sensor (psERS) was isolated from pea flowers, and the pattern of expression of its mRNA was studied during development and senescence of
different flower tissues. The levels of psERS mRNA paralleled ethylene production (and also levels of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) mRNA) in both
petals and styles. Silver thiosulfate treatments were efficient at preventing ACO and psERS mRNA induction in petals. However, the same inhibitor showed no ability to modify expression patterns in pea carpels around
the anthesis stage, suggesting different controls for ethylene synthesis and sensitivity in different flower organs.
Received: 18 June 1998 / Accepted: 22 December 1998 相似文献
930.