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J A Berry

Publications and source records attributed to J A Berry.

At least 37 records · Page 2Linked to original sources
PubMed1989

Low and High Temperature Limits to PSII : A Survey Using trans-Parinaric Acid, Delayed Light Emission, and F(o) Chlorophyll Fluorescence.

Many studies have shown that membrane lipids of chilling-sensitive plants begin lateral phase separation (i.e. a minor component begins freezing) at chilling temperatures and that chilling-sensitive plants are often of tropical origin. We tested the hypothesis that membranes of tropical plants begin lateral phase separation at chilling temperatures, and that plants lower the temperature of lateral phase separation as they invade cooler habitats. To do so we studied plant species in one family confined to the tropics (Piperaceae) and in three families with both tropical and temperate representatives (Fabaceae [Leguminosae], Malvaceae, and Solanaceae). We determined lateral phase separation temperatures by measuring the temperature dependence of fluorescence from trans-parinaric acid inserted into liposomes prepared from isolated membrane phospholipids. In all families we detected lateral phase separations at significantly higher temperatures, on average, in species of tropical origin. To test for associated physiological effects we measured the temperature dependence of delayed light emission (DLE) by discs cut from the same leaves used for lipid analysis. We found that the temperature of maximum DLE upon chilling was strongly correlated with lateral phase separation temperatures, but was on average approximately 4 degrees C lower. We also tested the hypothesis that photosystem II (PSII) (the most thermolabile component of photosynthesis) of tropical plants tolerates higher temperatures than PSII of temperate plants, using DLE and F(o) chlorophyll fluorescence upon heating to measure the temperature at which PSII thermally denatured. We found little difference between the two groups in PSII denaturation temperature. We also found that the temperature of maximum DLA upon heating was not significantly different from the critical temperature for F(o) fluorescence. Our results indicate that plants lowered their membrane freezing temperatures as they radiated from their tropical origins. One interpretation is that the tendency for membranes to begin freezing at chilling temperatures is the primitive condition, which plants corrected as they invaded colder habitats. An alternative is that membranes which freeze at temperatures only slightly lower than the minimum growth temperature confer an advantage.

Journal Article↗
PubMed1988

Plants and high temperature stress.

The effect of high temperature on higher plants is primarily on photosynthetic functions. The heat tolerance limit of leaves of higher plants coincides with (and appears to be determined by) the thermal sensitivity of primary photochemical reactions occurring in the thylakoid membrane system. Tolerance limits vary between genotypes, but are also subject to acclimation. Long-term acclimations can be superimposed upon fast adaptive adjustment of the thermal stability, occurring in the time range of a few hours. Light causes an increase in tolerance to heat, and this stabilization is related to the light-induced proton gradient. In addition to irreversible effects, high temperature may also cause large, reversible effects on the rate of photosynthesis. We report here some studies of photosynthetic gas exchange and chlorophyll fluorescence, designed to examine the energetic balance between photosynthetic carbon metabolism and light reactions during steady state photosynthesis with leaves of cotton plants at different temperatures. At temperatures exceeding the optimum for assimilation, but well below the tolerance limit, the feedback control of light reactions by carbon metabolism declines, as additional dissipative processes become important. Energy dissipated by photorespiration can exceed that consumed by CO2 assimilation, and a reversible, temperature-induced non-photochemical 'quenching' process, related to 'spillover' of excitation energy to photosystem 1, decreases the efficiency of photosystem 2 with increasing temperature. However, despite the overall decline in the 'potential quantum efficiency', our analysis indicates that CO2 assimilation may be limited, in part, at high temperature by an imbalance in the regulation of the carbon metabolism, which is reflected in a 'down-regulation' of the ribulose-1,5-bisphosphate carboxylase/oxygenase.

Adaptation, Physiological↗
PubMed1987

Isolation, identification, and synthesis of 2-carboxyarabinitol 1-phosphate, a diurnal regulator of ribulose-bisphosphate carboxylase activity.

The diurnal change in activity of ribulose 1,5-bisphosphate (Rbu-1,5-P(2)) carboxylase [3-phospho-D-glycerate carboxy-lyase (dimerizing); EC 4.1.1.39] of leaves of Phaseolus vulgaris is regulated (in part) by mechanisms that control the level of an endogenous inhibitor that binds tightly to the activated (carbamoylated) form of Rbu-1,5-P(2) carboxylase. This inhibitor was extracted from leaves and copurified with the Rbu-1,5-P(2) carboxylase of the leaves. Further purification by ion-exchange chromatography, adsorption to purified Rbu-1,5-P(2) carboxylase, barium precipitation, and HPLC separation yielded a phosphorylated compound that was a strong inhibitor of Rbu-1,5-P(2) carboxylase. The compound was analyzed by GC/MS, (13)C NMR, and (1)H NMR and shown to be 2-carboxyarabinitol 1-phosphate [(2-C-phosphohydroxymethyl)-D-ribonic acid]. Verification of structure was obtained by comparison of the inhibitory activity of the isolated compound with that of 2-carboxy-D-arabinitol 1-phosphate synthesized in vitro. This compound (but not 2-carboxy-D-arabinitol 5-phosphate) inhibited Rbu-1,5-P(2) carboxylase in a way that was kinetically identical to that of the isolated, naturally occurring compound. The structure of the isolated compound differs from the Rbu-1,5-P(2) carboxylase transition-state analogue 2-carboxyarabinitol 1,5-bisphosphate only by the lack of the C-5 phosphate group. This difference results in a higher binding constant for the monophosphate (K(d) = 32 nM) compared with the bisphosphate (K(d) < 10 pM). The less tightly bound compound acts in a light-dependent, reversible regulation of Rbu-1,5-P(2) carboxylase activity in vivo.

Journal Article↗
PubMed1986

Temperature and leaf osmotic potential as factors in the acclimation of photosynthesis to high temperature in desert plants.

Seasonal changes in the high temperature limit for photosynthesis of desert winter annuals growing under natural conditions in Death Valley, California were studied using an assay based upon chlorophyll fluorescence. All species of this group were 6 to 9 degrees C more tolerant of high temperature at the end of the growing season (May) than at its beginning (February). Over this same time period, the mean daily maximum air temperatures increased by 12 degrees C. Laboratory studies have demonstrated that increases in thermal tolerance could be induced by increasing growth temperature alone. For plants growing under field conditions there was also a good correlation between the thermal tolerance of leaves and the osmotic potential of leaf water, indicating that increases in the concentrations of some small molecules might also confer increased thermal tolerance. Isolated chloroplast thylakoids subjected to increasing concentrations of sorbitol could be demonstrated to have increased thermal tolerance.

Journal Article↗
PubMed1986

Regulation of Ribulose-1,5-Bisphosphate Carboxylase Activity in Response to Changing Partial Pressure of O(2) and Light in Phaseolus vulgaris.

The regulation of ribulose-1,5-bisphosphate (RuBP) carboxylase (rubisco) activity in Phaseolus vulgaris was studied under moderate CO(2) and high light, conditions in which photosynthesis in C(3) plants can be insensitive to changes in O(2) partial pressure. Steady state RuBP concentrations were higher, the calculated rate of RuBP use was lower and the activation state of rubisco was lower in low O(2) relative to values observed in normal O(2). It is suggested that the reduced activity of rubisco observed here is related to feedback effects which occur when the rate of net CO(2) assimilation approaches the maximum capacity for starch and sucrose synthesis (triose phosphate utilization). The activation state of rubisco was independent of O(2) partial pressure when light or CO(2) was limiting for photosynthesis. Reduced activity of rubisco was also observed at limiting light. However, in this species light dependent changes in the concentration of an inhibitor of rubisco controlled the apparent V(max) of rubisco in low light while changes in the CO(2)-Mg(2+) dependent activation of rubisco controlled the apparent V(max) in high light.

Journal Article↗
PubMed1986

Effects of pH on Activity and Activation of Ribulose 1,5-Bisphosphate Carboxylase at Air Level CO(2).

The effects of pH on catalysis and activation characteristics of spinach ribulose 1,5-bisphosphate (RuBP) carboxylase were examined at air level of CO(2). Catalysis at limiting CO(2) was independent of pH over the range of pH 8.2 to 8.8 However, the kinetics of activation and the apparent equilibrium between the activated and inactivated forms of the enzyme were strongly dependent upon the pH and the presence or absence of the substrate RuBP. When incubated at air level of CO(2) at pH 8.2 in the absence of RuBP, the enzyme activation state was approximately 75% of that achieved with saturating CO(2) at that pH. The extent of activation increased with pH reaching 100% at pH values of 8.6 or higher. Adding RuBP to the activation medium after equilibrium activation state had been established decreased the apparent equilibrium activation level at pH values below 8.6. This effect was reversed at pH values above 8.6. Activation of inactive enzyme by CO(2) and Mg(2+) was inhibited dramatically at pH values below 8.6 and less so at pH values above 8.6. Studies showed that binding of RuBP to the inactive form of the enzyme was pH dependent with tighter binding occurring at lower pH values. It is suggested that the tight binding of RuBP to the inactive enzyme tends to decrease the equilibrium concentration of the activated form at pH values less than 8.6. These studies indicate that stromal pH could have a strong effect on the activation state of this enzyme in vivo, and possible feedback interactions which might adjust the apparent V(max) to match the rate of RuBP regeneration are discussed.

Journal Article↗
PubMed1985

Regulation of ribulose bisphosphate carboxylase activity in vivo by a light-modulated inhibitor of catalysis.

The activity of ribulose 1,5-bisphosphate carboxylase [RuBPCase; 3-phospho-D-glycerate carboxylyase (dimerizing), EC 4.1.1.39] in leaf extracts of a number of species kept in the dark overnight was found to be very low. This was not the result of a change in the activation state or in the amount of enzyme that could be extracted from "dark" leaves. Rather, in Phaseolus vulgaris it was due to an inhibitor of catalysis that occupied the catalytic site of the enzyme. This inhibitor was compartmentalized in the chloroplast and its maximum concentration in both dark leaves and in intact chloroplasts made from such leaves was slightly in excess of the RuBPCase catalytic site concentration. The inhibitor (a phosphate ester) was bound preferentially to the activated form of the enzyme, apparently functioning as a positive effector of activation. Treatment of the enzyme-inhibitor complex in vitro with alkaline phosphatase could restore RuBPCase activity. In vivo, both the initial rate of disappearance and the final concentration of inhibitor in intact leaves was found to vary with light intensity, and these changes could account for observed light-dependent changes in RuBPCase activity, indicating that light modulation of inhibitor concentration controlled RuBPCase activity. Recovery of activity in vivo could be inhibited by 3-(3',4',4-dichlorophenyl)-1,1-dimethylurea.

Journal Article↗
PubMed1985

Starch and Sucrose Synthesis in Phaseolus vulgaris as Affected by Light, CO(2), and Abscisic Acid.

Phaseolus vulgaris L. leaves were subjected to various light, CO(2), and O(2) levels and abscisic acid, then given a 10 minute pulse of (14)CO(2) followed by a 5 minute chase with unlabeled CO(2). After the chase period, very little label remained in the ionic fractions (presumed to be mostly carbon reduction and carbon oxidation cycle intermediates and amino acids) except at low CO(2) partial pressure. Most label was found in the neutral, alcohol soluble fraction (presumed sucrose) or in the insoluble fraction digestable by amyloglucosidase. Sucrose formation was linearly related to assimilation rate (slope = 0.35). Starch formation increased linearly with assimilation rate (slope = 0.56) but did not occur if the assimilation rate was below 4 micromoles per square meter per second. Neither abscisic acid, nor high CO(2) in combination with low O(2) (thought to disrupt control of carbon metabolism) caused significant perturbations of the sucrose/starch formation ratio. These studies indicate that the pathways for starch and sucrose synthesis both are controlled by the rate of net CO(2) assimilation, with sucrose the preferred product at very low assimilation rates.

Journal Article↗
PubMed1984

Tolerance of photosynthesis to high temperature in desert plants.

Winter- and summertime-active desert annual species were grown at different temperatures to assess their capacity for photosynthetic acclimation. Thermal stability of photosynthesis was determined from responses of chlorophyll fluorescence to increased temperature. Photosynthesis in winter ephemerals grown at 28 degrees C/21 degrees C became unstable close to 41 degrees C in contrast to the summer annuals which were stable up to about 46 degrees C. Growth at higher temperature (43 degrees C/32 degrees C) resulted in increases in thermal stability of 5 to 7 degrees C for the winter annuals and 3 to 4 degrees C for the summer annuals, showing that temperature can provide the primary stimulus for acclimation of the photosynthetic apparatus. The magnitude of these changes was very similar to the range of field values observed for the respective floras, indicating that the thermal acclimation response under field conditions was qualitatively similar to that occurring under controlled growth conditions. Perennial species, co-existing with these annuals in the desert, were on average more thermostable. The cacti were exceptionally heat stable, the threshold for fluorescence increase averaging 55 degrees C.

Journal Article↗
PubMed1984

Variations in the Specific Activity of Ribulose-1,5-bisphosphate Carboxylase between Species Utilizing Differing Photosynthetic Pathways.

The in vitro specific activity of ribulose-1,5-bisphosphate carboxylase (RuBPCase) (micromoles CO(2) fixed per minute per milligram enzyme) from a number of C(3) and C(4) species and one green alga were measured. RuBPCases from species which utilize the C(4) pathway have a specific activity approximately 2-fold higher than those from C(3) species. RuBPCase from Chlamydomonas reinhardtii has a specific activity similar to the C(4) enzyme. Higher specific activity forms of RuBPCase are associated with a decreased enzyme affinity for CO(2) (increased K(m)[CO(2)]). A small but significant difference in the specific activity of RuBPCase from two C(4) decarboxylation types was also observed. The relationship between enzymic properties and the presence or absence of a CO(2) concentrating mechanism is discussed.

Journal Article↗
PubMed1984

Photosynthetic response and adaptation to high temperature in desert plants : a comparison of gas exchange and fluorescence methods for studies of thermal tolerance.

The temperature threshold for the onset of irreversible loss of photosynthetic capacity of leaves was examined in studies of net CO(2) exchange and by chlorophyll fluorescence techniques. Close agreement was found between the temperature threshold for a dramatic increase in the fluorescence of chlorophyll from intact leaves and the leaf temperature at which the capacity for photosynthetic CO(2) fixation (measured at rate saturating light intensity by infrared gas analysis) began to be temperature unstable (i.e. decline with time of exposure to a constant temperature). This decline in CO(2) uptake was not a result of a stomatal response yielding a reduced intercellular CO(2) concentration at high temperature, and it is interpreted as an indication of progressive damage to some essential component(s) of the leaf. The temperature-dependent change in chlorophyll fluorescence apparently also indicated the onset of this damage. The fluorescence assay could be conducted with discs of leaves collected from remote locations and kept moist while they were transported to a central location, allowing assessment of the high temperature tolerance of leaves which developed under natural field conditions. These assays were verified using a mobile laboratory to study gas exchange of attached leaves in situ. The high temperature sensitivity of leaves of plants growing under natural conditions were similar to those of the same species grown in controlled environments of similar thermal regimes. High temperature in controlled environment studies brought about acclimation responses which increased the threshold for high temperature damage as measured by gas exchange. Studies of fluorescence versus temperature confirmed that this method could be used to quantify these responses, and permitted the kinetics of the acclimation response to be examined. Gas exchange studies, while providing similar estimates of thermal stability, required more time, more elaborate instrumentation, and are particularly difficult to conduct with field plants growing in situ.

Journal Article↗
PubMed1984

Identification of Extracellular Carbonic Anhydrase of Chlamydomonas reinhardtii.

We have examined the induction of carbonic anhydrase activity in Chlamydomonas reinhardtii and have identified the polypeptide responsible for this activity. This polypeptide was not synthesized when the alga was grown photoautotrophically on 5% CO(2), but its synthesis was induced under low concentrations of CO(2) (air levels of CO(2)). In CW-15, a mutant of C. reinhardtii which lacks a cell wall, between 80 and 90% of the carbonic anhydrase activity of air-adapted cells was present in the growth medium. Furthermore, between 80 and 90% of the carbonic anhydrase is released if wild type cells are treated with autolysin, a hydrolytic enzyme responsible for cell wall degradation during mating of C. reinhardtii. These data extend the work of Kimpel, Togasaki, Miyachi (1983 Plant Cell Physiol 24: 255-259) and indicate that the bulk of the carbonic anhydrase is located either in the periplasmic space or is loosely bound to the algal cell wall. The polypeptide associated with carbonic anhydrase activity has a molecular weight of approximately 37,000. Several lines of evidence indicate that this polypeptide is responsible for carbonic anhydrase activity: (a) it appears following the transfer of C. reinhardtii from growth on 5% CO(2) to growth on air levels of CO(2), (b) it is located in the periplasmic space or associated with the cell wall, like the bulk of the carbonic anhydrase activity, (c) it binds dansylamide, an inhibitor of the enzyme which fluoresces upon illumination with ultraviolet light, (d) antibodies which inhibit carbonic anhydrase activity only cross-react with this 37,000 dalton species.

Journal Article↗
PubMed1984

Photosynthesis and Ribulose 1,5-Bisphosphate Concentrations in Intact Leaves of Xanthium strumarium L.

The interacting effects of the rate of ribulose 1,5-bisphosphate (RuBP) regeneration and the rate of RuBP utilization as influenced by the amount and activation of RuBP carboxylase on photosynthesis and RuBP concentrations were resolved in experiments which examined the kinetics of the response of photosynthesis and RuBP concentrations after step changes from a rate-saturating to a rate-limiting light intensity in Xanthium strumarium. Because RuBP carboxylase requires several minutes to deactivate in vivo, it was possible to observe the effect of reducing the rate of RuBP regeneration on the RuBP concentration at constant enzyme activation state by sampling very soon after reducing the light intensity. Samples taken over longer time periods showed the effect of changes in enzyme activation at constant RuBP regeneration rate on RuBP concentration and photosynthetic rate. Within 15 s of lowering the light intensity from 1500 to 600 microEinsteins per square meter per second the RuBP concentration in the leaves dropped below the enzyme active site concentration, indicating that RuBP regeneration rate was limiting for photosynthesis. After longer intervals of time, the RuBP concentration in the leaf increased as the RuBP carboxylase assumed a new steady state activation level. No change in the rate of photosynthesis was observed during the interval that RuBP concentration increased. It is concluded that the rate of photosynthesis at the lower light intensity was limited by the rate of RuBP regeneration and that parallel changes in the activation of RuBP carboxylase occurred such that concentrations of RuBP at steady state were not altered by changes in light intensity.

Journal Article↗
PubMed1982

Involvement of a Primary Electrogenic Pump in the Mechanism for HCO(3) Uptake by the Cyanobacterium Anabaena variabilis.

The response of the membrane potential to HCO(3) (-) supply has been studied in the cyanobacterium Anabaena variabilis strain M-3 under various conditions. Changes in potential were followed with the aid of the lipophilic cation tetraphenyl phosphonium bromide.Addition of HCO(3) (-) to CO(2)-depleted cells resulted in rapid hyperpolarization. The rate and extent of hyperpolarization were greater in low-CO(2)-adapted than in high-CO(2)-adapted cells. Addition of the electron acceptor p-nitrosodimethylaniline which resulted in O(2) evolution in CO(2)-depleted cells did not cause hyperpolarization. The hyperpolarization was not attributable to a change in pH or in ionic strength of the medium. Pretreatment with 3-(3,4-dichlorophenyl)-1,1-dimethylurea prevented the hyperpolarization. KCN depolarized hyperpolarized cells. Addition of HCO(3) (-) also brought about immediate K(+) influx which was succeeded after about 2 minutes by K(+) efflux.TWO OF THE MODELS CONSIDERED WOULD BE CAPABLE OF EXPLAINING THESE AND PREVIOUS FINDINGS: (a) a primary electrogenic pump for transporting HCO(3) (-) ions; (b) proton-HCO(3) (-) contransport, the driving force for which is generated by a proton pump which is sensitive to the HCO(3) (-) concentration.

Journal Article↗
PubMed1982

Growth Temperature-Induced Alterations in the Thermotropic Properties of Nerium oleander Membrane Lipids.

The temperature boundary for phase separation of membrane lipids extracted from Nerium oleander leaves was determined by analysis of spin label motion using electron spin resonance spectroscopy and by analysis of polarization of fluorescence from the probe, trans-parinaric acid. A discontinuity of the temperature coefficient for spin label motion, and for trans-parinaric acid fluorescence was detected at 7 degrees C and -3 degrees C with membrane lipids from plants grown at 45 degrees C/32 degrees C (day/night) and 20 degrees C/15 degrees C, respectively. This change was associated with a sharp increase in the polarization of fluorescence from trans-parinaric acid indicating that significant domains of solid lipid form below 7 degrees C or -3 degrees C in these preparations but not above these temperatures. In addition, spin label motion indicated that the lipids of plants grown at low temperatures are more fluid than those of plants grown at higher temperatures.A change in the molecular ordering of lipids was also detected by analysis of the separation of the hyperfine extrema of electron spin resonance spectra. This occurred at 2 degrees C and 33 degrees C with lipids from the high and low temperature grown plants, respectively. According to previous interpretation of spin label data the change at 29 degrees C (or 33 degrees C) would have indicated the temperature for the initiation of the phase separation process, and the change at 7 degrees C (or -3 degrees C) its completion. Because of the present results, however, this interpretation needs to be modified.Differences in the physical properties of membrane lipids of plants grown at the hot or cool temperatures correlate with differences in the physiological characteristics of plants and with changes in the fatty acid composition of the corresponding membrane lipids. Environmentally induced modification of membrane lipids could thus account, in part, for the apparently beneficial adjustments of physiological properties of this plant when grown in these regimes.

Journal Article↗
PubMed1981

Glycolate Excretion and the Oxygen to Carbon Dioxide Net Exchange Ratio during Photosynthesis in Chlamydomonas reinhardtii.

Chlamydomonas reinhardtii cells were grown in high (5% v/v) or low (0.03% v/v) CO(2) concentration in air. O(2) evolution, HCO(3) (-) assimilation, and glycolate excretion were measured in response to O(2) and CO(2) concentration. Both low- and high-CO(2)-grown cells excrete glycolate. In low-CO(2)-grown cells, however, glycolate excretion is observed only at much lower CO(2) concentrations in the medium, as compared with high-CO(2)-adapted cells. It is postulated that the activity of the CO(2)-concentrating mechanism in low-CO(2)-grown cells is responsible for the different dependence of glycolate excretion on external CO(2) concentration in low- versus high-CO(2)-adapted cells.The O(2)/CO(2) net exchange ratio is dependent on the CO(2) concentration in the medium and is linearly dependent on the fraction of glycolate excreted per CO(2) taken up. Glycolate excretion, however, is too low to account for the deviation of the O(2)/CO(2) net exchange ratio from unity.

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