Intensity of lipid peroxidation and concentration of free radicals in quail liver exposed to low-intensity laser irradiation to the embryo

The influence of low level red laser irradiation of Quails japanese embryos on lipid peroxidation level and free radicals concentration in the liver of young quails was estimated. It is detected that irradiation of the embryos in the dose of 15 mJ leads to the significant increase of peroxide lipid level and free radicals contents in the liver of one-day quails. In the liver of three-weeks quails an expressed antioxidant effect of red laser light irradiation of embryos is detected. The decrease of lipid peroxidation products and synthesis of ceruloplasmin in the liver of experimental group poultry confirm it. These changes are accompanied with cytochrome P-450 level increase and don't lead to inhibition of energetic system.     

Intracellular pH does not change during phytochrome-mediated spore germination in Onoclea

Calcium ions may act as a “second messenger” in phytochrome-mediated spore germination in Onoclea sensibilis L. In this study we determine whether changes in intracellular pH also contribute to the signal transduction chain. Using ³¹P nuclear magnetic resonance spectrometry, in which we are able to resolve changes as small as 0.2 pH units, we fail to observe any change in pH associated with red light irradiation. In addition artificially inducing an intracellular change in pH of greater than 1 pH unit (5.8-7.2) has no effect on germination. These data indicate that a sustained increase in intracellular pH does not contribute to the signal transduction chain in phytochrome-mediated fern spore germination.     

Properties of the pH-sensitive site that controls the lambda max of Limulus metarhodopsin

A pH-sensitive site controls the lambda max of Limulus metarhodopsin. The properties of this site were examined using intracellular recordings of the early receptor potential (ERP) as a pigment assay. ERPs recorded over a range of extracellular pHs indicate that the apparent pK of the site is in the range of 8.3-8.6. Several lines of evidence indicate that the site responds directly to changes in extracellular pH (pHo) rather than to changes in intracellular pH(pHi) that follow as a secondary result of changing pHo : (a) the effect of changing pHo was rapid (less than 60 s); (b) when pHo was raised, the simultaneous rise in pHi, as measured with phenol red, was relatively small; (c) raising pHi by intracellular injection of pH 10 glycine buffer did not affect the site; and (d) the effect of changing pH0 could not be blocked by increasing the intracellular pH buffering capacity. It is concluded that the pH-sensitive site on metarhodopsin is on the extracellular surface of the plasma membrane.     

The initiation of excitation and light adaptation in Limulus ventral photoreceptors

Two types of experiments indicate that light adaptation and excitation are initiated by the same, rather than different, populations of visual pigment. (a) The criterion action spectra of light adaptation and excitation are the same. (b) Increment-threshold curves were measured with a voltage-clamp technique under conditions of high and low concentration of plasma membrane rhodopsin (Rhpm). SD, the dark-adapted sensitivity, and 1/I2, the inverse of the background irradiance that desensitized by 0.3 log units, underwent the same fractional change when the rhodopsin concentration was changed. Both quantities appear to be linearly related to Rhpm. Reversible reductions in Rhpm were achieved by orange irradiation during a brief increase of extracellular pH from 7.8 to 10. This procedure would be unlikely to produce similar concentration changes in a hypothetical intracellular pigment because the concurrent change in intracellular pH, measured using the dye, phenol red, was only 0.45 pH units. It is thus unlikely that an intracellular pigment initiates light adaptation. On the assumption that light adaptation is mediated by a light-induced release of Ca++ from an intracellular store. the results reported here imply that an intracellular transmitter is needed to couple Rhpm to the intracellular store.     

Effect of Phytochrome on the Uptake of Gibberellin by Protoplasts of Nicotiana glutinosa L.

The effect of red light on gibberellin uptake by Nicotiana glutinosaL. protoplasts was determined. Five minutes of red light causedover a 50% inhibition of GA₃ uptake within 2 minutes. Five minutesof far red light completely reversed the red light effect. Theantagonistic effect of far red light indicates that gibberellinuptake is under phytochrome control. The rapid inhibition of gibberellin uptake indicates that phytochromeregulates the permeability properties of the plasma membraneas an initial response and not the intracellular binding ofgibberellin. ¹Department of Plant Pathology, University of Missouri. (Received October 28, 1985; Accepted April 23, 1986)     

The phosphate pool of isolated dog heart during global ischaemia: comparison of two cardioplegic solutions with 31P NMR spectroscopy.

31P NMR spectroscopy was used to study the time course of changes in the concentration of high-energy metabolites and intracellular pH in the dog myocardium during hypothermic ischaemia at 9 degrees C in Bretschneider (HTK-B) and St. Thomas' Hospital (StTH) cardioplegic solutions. It was found that ATP and phosphocreatine degrade slowlier in HTK-B than in StTH, with phosphocreatine depletion occurring within 7.9 +/- 1.4 h in HTK-B and within 6.2 +/- 1.4 h in StTH. The values are virtually identical with the time intervals at which ATP concentration falls below the critical level (60% of initial ATP concentration). In agreement with biochemical analysis, a higher concentration of phosphomonoesters was noted until the 180th minute of ischaemia in HTK-B, a finding suggesting more rapid glycogen degradation in HTK-B. Even though HTK-B contains a high concentration of histidine buffer, higher values of intracellular pH were found during ischaemia in StTH. The effect of extracellular concentration of sodium ions on intracellular pH is discussed.     

Ammonium chloride-induced acidification in renal TALH SVE.1 cells monitored by 31P-NMR.

The aim of this study was to investigate the effect of NH4+ on the intracellular pH in TALH SVE.1 cells derived from the medullary thick ascending limb of Henle's loop (TALH) of rabbit kidney. These cells are specialized to perform NH4+ transport in vivo. Intracellular pH was monitored by 31P-NMR. The steady state intracellular pH (pHi) under standard conditions was 7.24 +/- 0.04 (n = 46). Exposure to NH4Cl resulted in an initial intracellular acidification of the TALH SVE.1 cells, followed by a recovery to the initial steady-state pHi value. The NH4(+)-induced acidification followed saturation kinetics up to 20 mM NH4Cl (delta pHmax = 0.2 pHunits). Half-maximal acidification was observed at 0.6 mmol/l. The intracellular acidification due to NH4Cl exposure was completely inhibited by 0.1 mM of the diuretic bumetanide, an inhibitor of the Na+/K+/2Cl- cotransporter. The effect of bumetanide was dose-dependent and a Ki value of 8.10(-7) M was calculated. NH4+ influx via K+ channels or the (Na+ + K+)ATPase could not be detected. pHi recovery to the initial value was caused mainly by amiloride-sensitive Na+/H+ exchange and to a lesser extent by an amiloride-insensitive system, which was not studied in detail. In the presence of bumetanide, pulses of high concentrations of NH4Cl induced small intracellular alkalinizations. From these experiments, an intrinsic buffer capacity (beta i) in TALH SVE.1 cells of 26 +/- 3 mM x pH-1 (pHi = 7.65) was determined. It could also be shown that the TALH SVE.1 cells exhibit maximal 'functional buffer capability' between pHout 6.9 and 7.3. Within these limits the cells can maintain their intracellular pH at a constant level, even though the extracellular pH changes. These data strongly suggest that the Na+/K+/2Cl- cotransporter is the main site of NH4+ entry into rabbit thick ascending limb cells in culture. A high intracellular buffer capacity and potent acid extrusion mechanism cooperate in counteracting the intracellular acidification caused by NH4+ influx into the cell.     

红光下培养方式对雨生红球藻细胞增殖及其活力的影响

研究重点针对雨生红球藻绿色游动细胞的增殖培养阶段,分析了在利于细胞增殖的红光条件下,几种培养方式的调整对增殖过程和细胞活力的影响。结果显示:（1）在红光下,增殖平台期维持时间长,细胞活力稳定,细胞中性脂无累积,但进入平台期前,细胞中性脂有规律波动,进入平台期后相对稳定;通过更新率为20%的半连续培养,细胞数产出较批次培养提高57%;半连续培养中细胞呈现胁迫调节的时间较批次培养晚。随着培养时间增加,半连续培养下细胞营养盐吸收能力降低。（2）初始接种密度与细胞增殖速率及细胞光合活力呈负相关:初始密度低的细胞增殖速率较高,细胞光合作用活力高。（3）在培养过程中添加CO2时,最大密度均有提高,达6.0105 cells/mL,较无添加组提高54%;细胞分裂速率均有提高,但红光下较白光下增殖速率高（分别为0.223/d和0.198/d）;添加CO2降低培养液pH,利于维持适宜增殖的pH环境。叶绿素荧光参数以及细胞粒径在红光和白光下有显著差异:红光下,Fv/Fm显著高于白光下;红光下补充CO2显著减小细胞粒径,而白光下粒径无显著变化。研究结果显示,在红光下,采用间断式半连续培养补充CO2培养绿色游动细胞,有利于提升细胞活力与产出。     

Role of Calcium in Phytochrome-Controlled Nyctinastic Movements of Albizzia lophantha Leaflets

The involvement of Ca(2+) on phytochrome-controlled nyctinastic closure in Albizzia lophantha has been studied by testing the effect of the calcium ionophore 6S-[6alpha(2S(*),3S(*)),8beta(R(*)),9beta,11alpha]-5- methyl-amino)-2-[[3,9,11-trimethyl-8-[-1-methyl-2-oxo-2-(1H-pyrrol-2-yl) ethyl]-1,7-dioxaspiro[5.5]-undec-2yl] methyl]-4-benzoxazolecarboxylic acid (A23187) and the intracellular calcium antagonist 8-(diethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride (TMB-8). An external supply of Ca(2+) or calcium ionophore A23187 to the Albizzia leaflets emulates the effect of red light irradiation and counteracts the inhibitory effect of far red light. The intracellular calcium antagonist TMB-8 supplied to Albizzia leaflets inhibits the effect of red light, but had no effect on far red irradiated plants. This suggests a dependence between phytochrome action and intracellular free Ca(2+). We suggest that calcium acts as a phytochrome messenger on control of ion fluxes that drive turgor changes in pulvinular motor cells.     

Modification of bursting in a Helix neuron by drugs influencing intracellular regulation of calcium level

The effect of ruthenium red, caffein and EGTA (ethyleneglycol tetraacetic acid) influencing intracellular Ca2+ level as well as that of pH-lowering was investigated on identified RPal neuron of Helix pomatia characterized by bimodal pacemaker (bursting) activity. Drugs were applied both extracellularly and intracellularly. Intracellular injection was performed from micropipettes by pressure. It was found that intracellular injection of ruthenium red, caffein, EGTA and pH-lowering caused immediate short hyperpolarization and suspension of bursting. The effect of caffein and lowering of pH was biphasic, hyperpolarization was followed by an increase of spiking. Following EGTA injection the amplitudes of interburst hyperpolarizing waves decreased, and prolongation of spikes occurred. Extracellular application of ruthenium red caused slight depolarization, while caffein produced mainly effects that were similar to those of the intracellular injection. Adding EGTA into the bath resulted in cessation of bursting, and later on also spike generation was blocked. All these effects could be eliminated by washing. It is concluded that Ca-influx during spiking cannot be considered as a single factor in maintaining bursting activity, nevertheless, intracellular binding and liberation of Ca depending on the cell metabolism should also be taken into consideration as a possible mechanism of burst regulation.     

The buffering capacity of the internal phase of thylakoids and the magnitude of the pH changes inside under flashing light.

The buffering capacity inside thylakoids is determined and the magnitude of flash-induced pH changes inside is calibrated in the pH range from 6.4 to 8.1. The work is based on flash-induced absorption changes of neutral red in a chloroplast suspension in which the outer phase is strongly buffered by bovine serum albumin. It is shown that neutral red is bound inside thylakoids. The binding can be described by a simple isotherm with an apparent Km = 4 microM and satruation at 1 neutral red per 17 chlorophylls. The apparent pK of neutral red is shifted from 6.6 in solution to 7.25 when bound inside. It is demonstrated that neutral red is a clean indicator of pH changes inside, i.e. when properly used it shows no response to other events. Although bound it reports pH changes which occur in the internal osmolar (aqueous) volume of thylakoids. This is obvious from the influence of chemically very different buffers on the magnitude of the absorption changes of neutral red. These act in a manner proportional to their calculated buffering capacity in aqueous solution. The intrinsic buffering capacity of the internal phase is determined with the aid of these buffers, at pH 7.2 it is between 0.8 and 1 mM (at 60 mosM). The absence of large variations in the buffering capacity in the range from pH 6.4 to 8.1 suggests that proteinaceous groups are involved in addition to the lipids which may dominate the buffering capacity at lower pH. The magnitude of the internal pH change is arrpox. 0.6 (at pH 7.3) under stimulation of both photosystems with a short xenon flash of light.     

Role of light in the regulation of the nitrate reductase level in wheat (Triticum aestivum)

The relationship between light and NR synthesis was studiedin excised wheat leaves. In light, there was a 14 fold increasein the NR level as compared to the dark controls. Sucrose didnot have any effect on NR synthesis. In the dark, a significantamount of intracellular nitrate was detected, but there wasvery little NR activity. Measurement of the decay rates of NRin the dark and light showed that NR activity disappeared fasterin light than in the dark. Exposure to short durations of blue,red and white light caused an increase in the NR synthesis.Further, this response was found to be phytochrome controlled.We propose that the process of nitrate reduction influencesNR synthesis. (Received January 11, 1979; )     

Effect of pH, light intensity and population on the toxicity of the pesticide carbofuran to the blue-green alga Nostoc muscorum.

The effect of pH, light intensity and population on the toxicity of the pesticide furadan (containing 3% carbofuran as the active ingredient) was studied on the nitrogen fixing blue-green alga Nostoc muscorum. It was observed that all these factors had effects on the toxicity of the pesticide. The blue-green alga grew better in the pH range of 7.5-10, whereas the acidic pH of 5-6 retarded growth. The pesticide was more toxic to alga in the medium of pH 5-6, whereas reduction in toxicity was noticed in alkaline pH of 7.5-10. The alga grew slowly in a light intensity of 1,500 lux in comparison to a light intensity of 3,000 lux, and no growth occurred in the dark. The toxicity of the pesticide gradually decreased with increasing light intensity. The toxic effect of the pesticide was increased when the initial population level was low, and increasing the initial population reduced the toxicity.     

Modification of damaging effect of ultraviolet radiation on peritoneal macrophage membranes in mice

Different factors modificating damaging effect of middle-wave ultraviolet radiation (lambda max = 306 nm) on mice peritoneal macrophage plasma membranes were studied. It was shown that damaging effect of ultraviolet declined when the cells were simultaneously treated by red light (lambda max = 713 nm). This protective effect increased when a red component of light became greater and achieved almost 100% when it consisted 28.6%. It was also found that the decrease in intra- and extracellular pH led to the decrease in damaging effect of UVR. The increase of pH bring to an elevation of UVR destructive effect.     

Cytoplasmic pH of Dictyostelium discoideum amebae during early development: identification of two cell subpopulations before the aggregation stage

Development of the cellular slime mold Dictyostelium discoideum is initiated by the removal of nutrients, and results in formation of a mature fruiting body composed of two cell types, the stalk and spore cells. A considerable body of evidence supports the hypothesis that cytoplasmic pH may be an essential regulator of the choice to differentiate in either the prestalk or prespore pathway. We have devised methods for measurement and analysis of intracellular pH in developing Dictyostelium amebae in order to assess directly the potential role of cytoplasmic pH in regulating the pathway of differentiation. The intracellular pH of single D. discoideum amebae during development and in intact slugs has been measured using the pH-sensitive indicator pyranine in a low light level microspectrofluorometer. We have used the ATP-mediated loading method to introduce pyranine into these cells. Cells loaded by the ATP method appear healthy, have no detectable defects in development, and exhibit a similar population distribution of intracellular pH to those loaded by sonication. The intracellular pH of populations comprised of single amebae was found to undergo a transient acidification during development resulting in a bimodal distribution of intracellular pH. The subpopulations were characterized by fitting two gaussian distributions to the data. The number of cells in the acidic intracellular pH subpopulation reached a maximum 4 h after initiation of development, and had returned to a low level by 7 h of development. In addition, a random sample of single amebae within a slug had a median intracellular pH of 7.2, nearly identical to the median pH (7.19) of similarly treated vegetative cells. No gradient of intracellular pH along the anterior to posterior axis of the slug was detected. Our data demonstrate the existence of two distinct subpopulations of cells before the aggregation stage of development in Dictyostelium, and offers support for the hypothesis that changes in intracellular pH contribute to development in D. discoideum.     

Far-red light-induced changes in intracellular potentials of spinach mesophyll cells: interaction with red light

In green plants, the large bioelectric changes that photosynthetically active light stimulates make it difficult to observe electrical potential changes related to phytochrome photoconversion. As a first step towards distinguishing between photosynthetic and phytochrome effects, we showed that red light enhances far-red stimulated intracellular potential changes in spinach (Spinacia oleracea) leaf mesophyll cells.

For a dark-adapted leaf, the response to far-red light increased during the first 10 to 30 exposures of 2.5 minutes, after which it was constant. The intracellular potential depolarized by an average of 0.3 millivolts during each 2.5-minute far-red light period, and returned to the resting value during each subsequent dark period. Continuous supplementary red light (at 1-5% of the fluence rate of the far-red light that stimulated the depolarizations) increased the response to far-red 2- to 3-fold. Supplementary red light did not amplify the response to alternating 702 nanometers light and dark periods. The Emerson enhancement effect thus does not seem to explain amplification of the response to 730 nanometers light by supplementary red light. This does not prove that photosynthetic pigments are not involved in some other way.

     

Rapid,Blue-Light-Induced Acidifications at the Surface of Ectocarpus and Other Marine Macroalgae

In most brown algae, photosynthesis saturated with red light can be stimulated by continuous blue light. Pulses of blue light lead to transient increases in photosynthetic rate. When a CO2-sensitive electrode was used, occasionally blue light was observed to cause an apparent increase of CO2 instead of the expected decrease. This was changed by buffering the seawater medium and, under these conditions, blue light caused stimulation of CO2 consumption. These results led to investigations of blue-light-dependent pH changes at the outer surface of the plants. Shifts of the pH were recorded in the presence of the photosynthetic inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea. In all brown algae tested and in the green algae Ulva and Enteromorpha, blue-light pulses caused transient acidification of 0.03 to 0.18 pH units, depending on the species. The kinetics showed lag phases of a few seconds and the minimum was reached after 5 to 9 min. Fluence response relationships indicated that the sensitivity (threshold) to blue light was very similar in all species. The responses in Ectocarpus changed with time, and about 5 h after the beginning of red light or darkness, a second component became evident, which peaked 20 min after the blue-light pulse. The refractory period of the whole system was about 3 h in Ectocarpus. The blue-light-dependent pH changes show striking similarities to those of higher plant guard cells, and it is possible that similar responses may occur in other tissues of higher plants. In red algae, however, no blue-light-dependent acidifications could be detected. The possible role of the observed pH shifts in a mechanism of CO2 acquisition is discussed.     

The buffering capacity of the internal phase of thylakoids and the magnitude of the pH changes inside under flashing light

The buffering capacity inside thylakoids is determined and the magnitude of flash-induced pH changes inside is calibrated in the pH range from 6.4 to 8.1. The work is based on flash-induced absorption changes of neutral red in a chloroplast suspension in which the outer phase is strongly buffered by bovine serum albumin. It is shown that neutral red is bound inside thylakoids. The binding can be described by a simple isotherm with an apparent K_m = 4 μM and saturation at 1 neutral red per 17 chlorophylls. The apparent pK of neutral red is shifted from 6.6 in solution to 7.25 when bound inside. It is demonstrated that neutral red is a clean indicator of pH changes inside, i.e. when properly used it shows no response to other events. Although bound it reports pH changes which occur in the internal osmolar (aqueous) volume of thylakoids. This is obvious from the influence of chemically very different buffers on the magnitude of the absorption changes of neutral red. These act in a manner proportional to their calculated buffering capacity in aqueous solution. The intrinsic buffering capacity of the internal phase is determined with the aid of these buffers, at pH 7.2 it is between 0.8 and 1 mM (at 60 mosM). The absence of large variations in the buffering capacity in the range from pH 6.4 to 8.1 suggests that proteinaceous groups are involved in addition to the lipids which may dominate the buffering capacity at lower pH. The magnitude of the internal pH change is approx. 0.6 (at pH 7.3) under stimulation of both photosystems with a short xenon flash of light.     

Blood oxygen equilibria and theoretical models. I. Effect of protons in trout (Salmo gairdneri) and human red cells, in absence of organic phosphates

1. Oxygen equilibrium curves were measured on red cells that had been depleted of organic phosphates, for rainbow trout red cells between pH 7-9, at 15 and 20 degrees C, and for human red cells between pH 6.8-8.0, at 37 degrees C. 2. The data were fitted to the models of Adair and of Monod et al. (MWC model). Parameters were estimated by the non-linear least-squares method, from which the number of Bohr protons released during oxygenation was calculated. 3. For trout as for human red cells, the pH affects the first step of oxygenation and the overall oxygenation in nearly equal proportion. For human red cells, the association constant for binding of the last oxygen, expressed by k4 or kR, is not affected by pH, indicating that the R structure is free of constraints. For trout red cells, there is a pronounced pH dependence of this constant at low pH, which is about 10-fold increased between pH 7-9. This corresponds to the Root effect that impairs the T----R transition, and confirms previously published data for normal trout and human red cells. 4. For trout red cells, small functional heterogeneity is evidenced, despite Hb multiplicity, and effect seems linked to the level of temperature. 5. The specific effect of organic phosphates, evident for human red cells, contrasts with a lack of effect for trout red cells, when taking into account the intracellular pH values.     

光照和pH对忍冬纤孔菌液体培养的影响

以液体培养为基础,研究不同光照和培养液初始pH条件下,忍冬纤孔菌培养过程中生物量、胞内外多酚含量,以及胞内外提取物抗氧化活性的变化。结果显示,24h光照轻微抑制菌丝体的生长,但能促进胞内外多酚的形成和提取物对DPPH自由基的抑制;在初始培养液pH5.3条件下,菌丝体生物量最高,胞内外多酚含量和提取物活性最高。