Space proton flux and the temporal distribution of cardiovascular deaths

 The influence of solar activity (SA) and geomagnetic activity (GMA) on human homeostasis has long been investigated. The aim of the present study was to analyse the relationship between monthly proton flux (>90 MeV) and other SA and GMA parameters and between proton flux and temporal (monthly) distribution of total and cardiovascular-related deaths. The data from 180 months (1974–1989) of distribution in the Beilinson Campus of the Rabin Medical Centre, Israel, and of 108 months (1983–1991) from the Kaunas Medical Academy, were analysed and compared with SA, GMA and space proton flux (>90 MeV). It was concluded: (1) monthly levels of SA, GMA and radiowave propagation (Fof2) are significantly and adversely correlated with monthly space proton flux (>90 MeV); (2) medical-biological phenomena that increase during periods of low solar and/or geomagnetic activity may be stimulated by physical processes provoked by the concomitant increase in proton flux; (3) the monthly number of deaths related (positively or negatively) to SA are significantly and adversely related to the space proton flux (>90 MeV). Received: 14 January 1996 / Accepted: 14 October 1996     

Regulation of Metabolite Flux through Voltage-Gating of VDAC Channels

The mitochondrial outer membrane channel, VDAC, is thought to serve as the major permeability pathway for metabolite flux between the cytoplasm and mitochondria. The permeability of VDAC to citrate, succinate, and phosphate was studied in channels reconstituted into planar phospholipid membranes. All ions showed large changes in permeability depending on whether the channel was in the open or in the low conductance, ``closed' state, with the closed state always more cation selective. This was especially true for the divalent and trivalent anions. Additionally, the anion flux when the voltage was zero was shown to decrease to 5–11% of the open state flux depending on the anion studied. These results give the first rigorous examination of the ability of metabolites to permeate through VDAC channels and indicate that these channels can control the flux of these ions through the outer membrane. This lends more evidence to the growing body of experiments that suggest that the outer mitochondrial membrane has a much more important role in controlling mitochondrial activity than has been thought historically. Received: 4 November 1996/Revised: 8 January 1997     

An analysis of proton fluxes coupled to electron transport and ATP synthesis in chloroplast thylakoids

Electron transport, phosphorylation and internal proton concentration were measured in illuminated spinach chloroplast thylakoid membranes under a number of conditions. Regardless of the procedure used to vary these parameters, the data fit a simple chemiosmotic model. Protons from Photosystem II did not appear to be utilized differently from those derived from Photosystem I. The maximal phosphorylation efficiency ($\text{P}\text{e}{}_2$) for photophosphorylation in washed thylakoids under oxidizing conditions is likely to be $\text{4}\text{3}$. This value is consistent with a proton-to-electron-pair ratio of 4 for electron flow through both photosystems and a proton-to-ATP ratio of 3 for the chloroplast proton-ATPase.     

Short-term variations in catches of the pea moth,Cydia nigricana, in interacting pheromone traps

Short-term variations in the relative catch in each of two or three interacting pheromone traps for the pea moth,Cydia nigricana (F.), were investigated for traps aligned along the wind. The proportional catch in each trap varied widely, although the mean values accorded with previous estimates. Over consecutive short intervals during a single trapping period the proportion caught in the centre trap of a three-trap line was constant. The proportion caught in the upwind trap of two-and three-trap lines showed trends in time. These trends differed between trapping periods, but two lines of traps operated simultaneously gave similar results to each other. It is suggested that these results, which are predicted by a model based on various components of moth orientation behaviour, are caused by changes in systematic behavioural processes, not random effects. Possible mechanisms are discussed.

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Variations à court terme des captures deCydia nigricana dans des pièges à phéromones en interaction

Résumé Des données antérieures concernant les interactions entre des pièges à phéromone alignés le long du vent ont été utilisées pour déduire les caractéristiques du comportement d'orientation deC. nigricana. Ces données ont été introduites dans un modèle de simulation quantitative qui prédisait que quand les captures totales sur une ligne ont été regroupées sur une période globale de piégage, la proportion capturée dans chaque piège devrait aussi avoir des valeurs moyennes semblables, mais varie plus largement que précédemment indiqué. Les simulations concernant des intervalles consécutifs beaucoup plus courts pendant la même période de piégage ont suggéré une forme spécifique de cette variation.Cette note signale des variations à court terme dans la proportion capturée au piège qui confirment ces prédictions. Nous montrons que sur des intervalles consécutifs brefs pendant une simple période de piégage, la proportion capturée dans le piège central d'une ligne de 3 pièges est contstante, bien que sa valeur change suivant les périodes de piégage. La proportion capturée dans le piège face au vent de 2 ou 3 lignes de pièges suit cette tendance dans le temps, ce qui est généralement bien représenté avec des courbes simples. Ces tendances changent suivant les périodes de piégage, mais des lignes de pièges fonctionnant simultanément fournissaient des résultats similaires. On suggère que ces résultats sont dus à des changements dans des processus comportementaux systématiques et non à des effects aléatoires. Les mécanismes possibles sont discutés.

     

Auxin action on proton influx in corn roots and its correlation with growth

At concentrations inhibitory to the elongation of corn (Zea mays L.) roots, the auxins, indole-3-acetic acid (IAA) and α-naphthaleneacetic acid (α-NAA), cause an increase in the pH of the bathing medium; this increase occurs with an average latent period shorter than the latent period for the inhibitory effect of these auxins on elongation. Indole-2-carboxylic acid, an inactive structural analogue of IAA, and β-naphthaleneacetic acid, an inactive analogue of α-NAA, affect neither growth nor the pH of the medium. Since acid pH is known to promote and basic pH to inhibit root elongation, the data are consistent with the hypothesis that hormone-induced modification of cell-wall pH plays a role in the control of elongation of roots, as has been proposed for elongation of stems and coleoptiles.     

Role of three basic light reactions in photomovement of desmids

Photoaccumulations in light trap experiments have been studied in the desmids, Cosmarium, Micrasterias and Euastrum. Dependence of accumulation density on exposure time follows saturation curves, while dose response curves show optima. Time-lapse microcinematography and population methods have revealed that all three basic light-induced motor responses known in microorganisms participate in producing photoaccumulations in desmids. During the initial phase the cells are phototactically attracted towards the trap by scattered light. In low light intensity traps photokinetic reactions may play only a minor role, since photokinesis could be evoked only by light intensities100 lx in Cosmarium cucumis. True photophobic reactions have been demonstrated for the first time in desmids. There are two types of phobic responses in desmids: either the cell reverses its movement or it swings sidewise into the new direction. Behaviour of partially shadowed cells suggests that perception of light direction is brough about by simultaneous intensity measurement at two or more sites within the cell.     

Radical-Induced Damage to Proteins: E.S.R. Spin-Trapping Studies

The reactions of hydroxyl radicals generated from Fe¹¹/H₂O₂ and Cu¹¹/H₂O₂ redox couples with a variety of proteins (BSA, histones, cytochrome c, lysozyme and protamine) have been investigated by e.s.r. spin trapping. The signals obtained, which are generally anisotropic in nature, characterize the formation of partially-immobilized spin-adducts resulting from attack of the HO- radicals on the protein and subsequent reaction of the protein-derived radicals with the spin trap. Similar spin adducts are observed on incubation of two haem-proteins (haemoglobin and myoglobin) with H₂O₂ in the absence of added metal ions implying a reaction at the haem centre followed by internal electron transfer reactions.

Two strategies have been employed to obtain information about the site(s) of radical damage in these proteins. The first involves the use of a variety of spin traps and in particular DMPO: with this particular trap the broad spectra from largely immobilized radicals show characteristic a(β-H) values which enable carbon-, oxygen- and sulphur-centred radicals to be distinguished. The second involves the use of enzymatic cleavage of first-formed adducts to release smaller nitroxides, with isotropic spectra, which allow the recognition of β-proton splittings and hence information about the sites of radical damage to be obtained. These results, which allows backbone and side-chain attack to be distinguished, are in agreement with random attack of the HO^. radical on the protein and are in accord with studies carried out on model peptides. In contrast the use of less reactive attacking radicals [N₃·, ·CH(CH₃)OH] and oxidising agents (Ce⁴⁺) provides evidence for selective attack on these proteins at particular residues.     

Effects of Cu,Pb and Zn on two Potamogeton species grown under field conditions

Two common macrophyte species, Potamogeton perfoliatus L. and Potamogeton pectinatus L. were grown for 12 weeks at shallow depths in sediments contaminated with 1250 or 2500 g Pb or Cu and/or Zn (gDW sediment)^-1. Control experiments were run at background levels of 4, 13, and 38 g Pb, Cu and Zn (gDW sediment)^-1, respectively. Effects of heavy metals on biomass production and metal uptake and distribution in plants are presented in relation to total amount and plant-available fraction of metals in the sediment.All three studied metals gave reduced biomass production, and the toxicity of the metals decreased in the order Zn>Cu>Pb. The root/shoot biomass ratio increased for P. pectinatus, but decreased for P. perfoliatus with metal treatment. The content of any single metal was higher in shoots than in roots of plants grown on sediments not contaminated with that specific metal, but addition of that metal increased the proportion in roots. The uptake by plants of any of the heavy metals increased with increased metal addition. The magnitude of the plant-available fraction of metals of untreated sediment was Zn>Cu>Pb, and increased in contaminated sediments. Addition of Cu decreased both the plant-available fraction and the total concentration of Zn in the sediment, while increased the uptake of Zn by the plants. The opposite was found for Cu when Zn was added. P. pectinatus accumulated about twice as much Cu as P. perfoliatus. On the other hand, the concentration of Pb was higher in P. perfoliatus than in P. pectinatus, and was negligible in P. pectinatus when cultivated in untreated sediments.     

Potentiation of γ-Aminobutyric Acid-Mediated Chloride Flux by Pentobarbital and Diazepam but Not Ethanol

The influx of 36Cl- into cerebral cortical and cerebellar microsacs from ICR mice and Sprague-Dawley rats was studied in incubations lasting 3 s, 500 ms, or 21 ms. In the 3-s assay, 10-40 mM ethanol did not affect either basal or gamma-aminobutyric acid (GABA)-mediated Cl- flux, at any GABA concentration tested. Only at a concentration of 600 mM did ethanol potentiate Cl- flux in both mouse and rat preparations. Ethanol (20 mM) also did not affect the significant potentiation of GABA-mediated flux produced by 50 microM pentobarbital or 2 microM diazepam in ICR mouse microsacs. In 21- and 500-ms incubations (quench-flow method), 50 microM pentobarbital significantly potentiated GABA-mediated Cl- flux in rat cortical microsacs, but 10-50 mM ethanol did not. These studies suggest that some as yet unrecognized factor is essential for ethanol enhancement of GABA-mediated Cl- flux, as reported by others in brain homogenates and in tissue culture.