bluuebunny/crossref_metadata_2025 huggingface dataset:
The Structures of Political, Economic, and Socio-cultural Rhetorical Narratives on Social Media
Authors: Gunawan Samuel , Riyanto Theopilus Joko , Limanta Liem Satya
Published: March 2024

This research was conducted on the ground of the reason for the increasingly widespread use of narratives on various social media platforms. Narrative  is an event whereby someone  represents an event  aiming to influence the understanding, emotions and values of others. This study qualitatively aims to capture the most common elements of narrative structure focusing on political, economic, and socio-cultural rhetorical narratives data originated from social media platforms. The theoretical model of narrative structure consisting of Abstract, Orientation, Complicating Actions, Resolution, Evaluation and Coda, as proposed by Labov and Waletzky was used to analyze the narrative data collected during the first four months of 2022. On the ground of social situated meanings, the findings show that the most common model of narrative structure is fully used whenever greater details of events, facts, or information are needed to be emphasized. For such reasons, all the elements of narrative structure are held to be obligatory. The findings  show that some elements of narrative structure are left out and  held to be optional as such elements are not considered necessary to convey the main content. In addition, the findings also show that some particular element allows it to be further developed with more embedded events, facts, opinion, or information.
Text and Practice in Teaching Translation: Documenting the Process
Authors: Rini Julia Eka
Published: March 2024

Documenting the process of translation has several advantages for both teachers and students in a translation class in an English, or any language, department. It is not only useful for preventing the students from using translation applications in doing the assignments, but also useful for teaching them to evaluate and to revise their translation. Besides making students accustomed to expressing their thoughts in writing, process-oriented teaching inspires them to think in detail and inspires lecturers to conduct process-oriented translation research.
Solah Bawa Free Movement as a Whole Person Art Practice
Authors: Kusumaningtyas Purwanti
Published: March 2024

Solah bawa, a meditative free movement dance, was developed by Sitras Anjilin (the head of Padhepokan Seni (art center and workshop) Tjipta Boedaja, Tutup Ngisor, Kabupaten Magelang, Central Java). A participatory observation towards a group named Komunitas Sabtuan, guided by Sitras Anjilin, and an etic interpretive analysis of the activity’s details found that solah bawa free movement reflects whole person aspects of human quality development. This article explicates how such art activity as free movement dance can be done by individuals to enhance whole person development. It argues that regular art practice can help individuals develop themselves holistically, and thus, it can promote balanced life.
The path of photosynthate translocation into citrus fruit
Authors: KOCH KAREN E.
Published: April 2006

Abstract The path of [14C]photosynthate translocation into citrus fruit was examined to determine which anatomical and physiological features were involved in this process. Experiments were conducted during the final pre‐harvest months of 2 years grapefruit crops (Citrus paradisi Macf. cv. ‘Marsh’). A source leaf nearest the fruit was exposed to 14CO2 for 1 h + 5 h ambient air, followed by dissection of vascular and phloem‐free tissues in the fruit quarter directly aligned with the source. Radioactivity in each tissue was quantified after separation and extraction in boiling 80% ethanol. Peel (flavedo+albedo) contained an average 35% of the label in the quarter fruit, but an additional 20% was localized entirely in dorsal vascular bundles along exterior walls of juice segments. Less [14C]photosynthate was recovered from other vascular tissues and was nearly absent from adjacent mature seeds. Radioactivity in the single layer of segment epidermis, however, averaged 17% of that in the quarter fruit. Juice tissues interior to this accumulated only 17% of the total. No phloem tissue was evident in either the segment epidermis or juice tissues, but over 70% of the [14C]assimilates in the latter were localized in thread‐like stalks which attach juice vesicles to dorsal vascular bundles. In addition, labelled hexose/sucrose ratios in these structures increased with distance from the vascular bundle. The majority of photosynthates, therefore, entered citrus fruit via dorsal vascular bundles and were partially hydrolysed during slow transfer through non‐vascular segment epidermis and juice stalks.
An examination of the importance of ethanol in causing injury to flooded plants
Authors: JACKSON MICHAEL B. , HERMAN BARRY , GOODENOUGH ANNABELLE
Published: April 2006

Abstract.We have examined the widely held theory that ethanol toxicity is a prime cause of the injury and death of plants in soil flooded with water. The tests were made on peas (Pisum sativumL.) at the early flowering or fruiting stages, when they are known to be severely injured by flooding.

Supplying ethanol in aerobic or anaerobic nutrient solution at similar concentrations to those we found in flooded soil (up to 3.9 mol m−3) or in the xylem sap of flooded pea plants (up to 2.1 mol m−3) caused no injury. One hundred times these concentrations gave little extra effect and failed to simulate flooding injury. Isolated leaf protoplasts and detached leaves were also resistant to damage by ethanol at these concentrations.

Other published measurements of ethanol concentrations in flooded plants are similar to or less than those we report for pea plants. Exceptions include root nodules and germinating pea seeds. Reports by others of responses to applied ethanol in a wide variety of circumstances confirm that in flooded plants the amounts are probably too small to explain the observed injury. Alternative mechanisms are discussed.
Analysis of particle motion in sieve tubes of Heracleum
Authors: BARCLAY GREGOR F. , JOHNSON RICHARD P. C.
Published: April 2006

Abstract. We have cine‐filmed the random motion of microscopic particles, mostly starch grains from ruptured plastids, in sieve tubes of Heracleum mantegazzianum L. and H. sphohdylium Somm. and Lev. Our frame‐by‐frame analysis of the positions of the particles shows that they move much less than calculated when generally accepted estimates for the viscosity of sieve‐lube sap are inserted in the Stokes‐Einstein and other equations for Brownian motion. Our analysis of a film, of similar particles, made by previous workers leads us to disagree with their conclusion that particle movement in sieve tubes was greater than should be expected for ordinary Brownian motion. Particles in their film and in ours moved less than expected even when we allow for the possibility that the particles are restricted by cell walls and by each other. We suggest that the particles move less than expected because the viscosity of sieve‐lube sap may be higher than has been assumed by physiologists.
A portable system for measuring carbon dioxide and water vapour exchange of leaves
Authors: FIELD C. , BERRY J. A. , MOONEY H. A.
Published: April 2006

Abstract. The apparatus described here is a fully portable, steady‐state gas exchange system for simultaneous measurements of the CO2 exchange and transpiration of single, attached leaves. The leaf cuvette provides temperature, humidity, and CO2‐concentration control. The system is suitable for either surveys or detailed studies of photosynthetic and stomatal responses to environmental variables. Representative data demonstrate the response time characteristics of the system and constitute the first field evidence of stomatal behaviour consistent with a recent hypothesis concerning the optimum pattern of stomatal conductance for the maximization of water‐use‐efficiency.
Effects of low level O3 exposure on leaf diffusive conductance and water‐use efficiency in hybrid poplar
Authors: REICH PETER B. , LASSOIE JAMES P.
Published: April 2006

Abstract Young, amphistomatous hybrid poplar (Populus deltoides x trichocarpa) plants were exposed daily to either background (0.025 cm3 m‐3) or elevated (0.125 cm3 m‐3) concentrations of O3. Levels of abaxial and adaxial leaf conductance were affected interactively by pollutant treatment, leaf age, and photon fluence rate. Consequently, conductance in O3‐treated leaves was sometimes higher and sometimes lower than in comparable control leaves, depending on leaf age or level of photon fluence rate. For example, at low photon fluence rate or in the dark, conductance was greater in O3‐treated than in control plants, while at high photon fluence rate that relationship was reversed. Exposure to O3 also reduced the water‐use efficiency and range of leaf conductance of individual leaves, and altered the relationship between the conductances of the two leaf surfaces (the ratio of abaxial to adaxial leaf conductance was increased). Furthermore, O3 treatment resulted in diminished stomatal control of water loss; excised O3‐treated leaves had higher conductances and wilted sooner than excised control leaves of identical ages. Overall, the data indicate that exposure to O3 resulted in impaired stomatal function.
Frost avoidance and freezing tolerance in Afroalpine ‘giant rosette’ plants
Authors: BECK ERWIN , SENSER MARGOT , SCHEIBE RENATE , STEIGER HANS‐MARTIN , PONGRATZ PAUL
Published: April 2006

Abstract. The large leaf rosettes of the so‐called ‘giant rosette’ plants which inhabit the alpine region of tropical mountains are composed of a great number of adult leaves surrounding a central cone of developing leaves. Upon onset of the nocturnal frost period the adult leaves nyctinastically bend inwards and form a night‐bud around the central leaf bud. The insulating effect of the night‐bud was analysed in four species: Senecio keniodendron, Senecio brassica. Lobelia keniensis and Lobelia telekii which grow on Mt Kenya (Kenya). Freezing is avoided by a delay of cooling which is sufficient until rewarming by the next day's sunshine. A consequence of this delay is that the temperature in the nocturnal bud remains higher than that of the outer leaves which are often stiffly frozen after cold nights. Only one freezing point was detected on the leaf temperature recordings. Depending on the water state, the freezing points were in the range — 1°C to —4.2°C. Sucrose, amounting to 38% of the leaf dry weight, may act as a cryoprotectant for the cell membranes. Frost hardiness of the leaves, as determined with a laboratory method, was sufficient to enable the plants to survive during the nocturnal frost temperatures as measured in the field.
Experimental systems and a mathematical model for studying temperature effects on pollen‐tube growth and fertilization in plum
Authors: JEFFERIES C.J. , BRAIN P. , STOTT K. G. , BELCHER A. R.
Published: April 2006

Abstract. Cross and self pollen tubes were cultured in ‘Victoria’ plum flowers (Prunus domestica L.) at 5, 10, 15 and 20°C. Pollen‐tube lengths measured at intervals were fitted by S‐shaped growth curves (logistic function) and the parameters of the curves used to derive a generalized model for pollen‐tube growth based on accumulated temperatures. Above the threshold of 2.5°C, maximum growth rate was 0.34 mm per day‐degree and the tubes reached half their final length at 16.6 day‐degrees above 2.5°C. The model indicates that fertilization of plum flowers requires 16–20 d at a constant temperature of 5°C after pollination, but only 3–4 d at 15°C. Mathematical expressions based on the model are given for estimating pollen‐tube penetration and growth rate from values of cumulated temperature since pollination, and for estimating the cumulated temperature necessary for pollen tubes to penetrate a given distance. Pollen‐tube growth rates were the same in detached flowers, flowers attached to twigs, and flowers on young, grafted trees in pots. In detached flowers growth stopped before fertilization could occur, but some embryo sacs were fertilized in both the remaining treatments. Accurate pollen‐tube growth assessments can therefore be made with detached flowers which are most convenient to use and can be accommodated in small incubators. Studies on fertilization, however, must use flowers on bulky and expensive grafted trees.
Acid phosphatase activity in intercellular spaces in roots of Nymphoides peltata (S. G. Gmel.) O. Kuntze
Authors: OPARKA K. J. , JOHNSON R. P. C.
Published: April 2006

Abstract. Acid phosphatase was found cytochemically in intercellular spaces in the root of Nymphoides peltata. Different methods, using lead salts and azo‐dyes, gave similar results. Reaction product appeared on material, possibly cytoplasmic, within the intercellular spaces and also against the outer walls of cells which formed the intercellular spaces. Possible functions of acid phosphatase in intercellular spaces are discussed.
A bimodal germination response to temperature in cocklebur seeds. I. Cyanide‐sensitive and cyanide‐resistant respirations
Authors: ESASHI YOHJI , ISHIHARA NOBUYORI , SAIJOH KEIICHI , SATOH MOTONOBU
Published: April 2006

Abstract. Pre‐imbibed cocklebur (Xanthium penn‐sylvanicum Wallr.) seeds displayed bimodal germination‐temperature responses with two optima at 8 and 33° C. Such germination responses occurred subsequent to bimodal respiration‐temperature upsurges at lower and higher temperature regions. At lower temperatures, cocklebur seeds respired predominantly through a cyanide‐sensitive cytochrome pathway. A rise in temperature resulted in a marked increase in flux via an alternative pathway, a propyl gallate‐ (PG) or benzohydroxamic‐acid‐ (BHAM) sensitive pathway, thus resulting in an increase in the ratio of this pathway relative to the cytochrome pathway. Both an increased capacity for the alternative pathway and an increase in the ratio of this pathway to the cytochrome pathway were obtained when pre‐imbibed seeds were exposed to either 8 or 33°C for a short period. The effects of low temperature were reduced as the exposure time was prolonged beyond 3d, resulting in a reduction in germination. Neither PG nor BHAM had an inhibitory effect on the chilling‐induced germination, but the germination‐stimulating effect of high temperatures was less pronounced in the presence of PG or BHAM. At high temperatures, on the other hand, KCN and NaN3 were ineffective or, rather, slightly inhibited germination. It was thus concluded that low and high temperatures exert their germination‐stimulating effects by an essentially similar manner which increases fluxes both via the cytochrome pathway and, especially, via the alternative pathway and, as a result, raises the ratio of the latter to the former.
A bimodal germination response to temperature in cocklebur seeds. II. ATP and adenylate pool
Authors: ESASHI YOHJI , NAGAYAMA TAKAO , SATOH MOTONOBU , SAIJOH KEIICHI
Published: April 2006

Abstract. The mechanism involved in a bimodal germination‐temperature response in pre‐soaked cocklebur (Xanthium pennsylvanicum Wallr.) seeds was studied with special reference to adenylate metabolism. Exposure to either low (optimal at 8°C) or high (optimal at 34°C) temperature which was effective in inducing the germination of the seeds brought about the accumulation of ATP in them. The ATP level remained unchanged at temperatures around 23°C. Pretreatment with KCN, stimulating germination even at 23°C, subsequently increased the ATP content, total adenylate pool and energy charge (EC) in the axial tissue prior to germination above those of the untreated controls. The lower the treatment temperature, the greater the inhibitory effect of KCN on ATP formation. An increase in germination following an increasing duration of pre‐soaking at 8°C was comparable to increasing both the ATP content and total adenylate pool of axes, but not the EC value. Similarly, changes in germination following an increased exposure duration at 8°C correlated with changes in ATP content rather than EC value in the axes. Unlike the case of chilling, an increase in ATP level in response to 34°C was greater in the early period of water imbibition, during which times its germination‐stimulating effect appeared more striking than in the later period, and it occurred without a concomitant rise in EC value because of the increased supply of AMP. Such a supply of AMP was reduced in the presence of benzohydroxamic acid or propyl gallale, inhibitors of an alternative respiratory pathway. It was thus concluded that both low temperature, coupled with warm temperature, and high temperature, by itself, can induce seed germination by increasing the ATP level as well as the total adenylate pool, but not the EC value, in the axial tissue. Further, that increases in both the ATP level and the adenylate pool especially are required for seed germination to proceed, probably depending on the activities of the cytochrome and alternative respiration pathways, respectively.
Radioimmunoassay of phytochrome content in green, light‐grown oats
Authors: HUNT ROBERT E. , PRATT LEE H.
Published: April 2006

Abstract. We measured phytochrome content by radioimmunoassay in green, light‐grown oats (Avena sativa L., cv. Garry) grown under several light regimes. Phytochrome content increased linearly to six times the light‐grown level during a 24‐h dark incubation and to fifty times the light‐grown level after 48 h darkness. Phytochrome content, in response to a cycle of 12‐h light, 12‐h dark photoperiods, increased to three times the light‐grown level in darkness and returned to the light‐grown level during the subsequent light period. Plants given far‐red light immediately prior to a 12‐h dark period contained about four‐fold more phytochrome than light‐grown oats, compared with a three‐fold increase in plants treated identically except given no far‐red light. We also attempted, unsuccessfully, to eliminate a general nonspecific interference by crude plant extracts with the radioimmunoassay.
Allocation of carbon to growth, storage and respiration in the vegetative barley plant
Authors: FARRAR J. F.
Published: April 2006

Abstract. It is proposed that the growing plant can be divided into three compartments with reference to carbon: soluble, storage and structural. Experiments carried out at 10, 15, 20 and 30°C in the light followed changes in size of these compartments in barley plants 10–24 days old. The redistribution of I4C photo‐assimilated by 10 day old plants was monitored simultaneously. The soluble and storage compartments are a higher percentage of plant weight at lower temperatures, and are turned over rapidly at all temperatures; they form the source of respired 14C. About 30% of the 14C fixed enters structural material; in the first 24 h after labelling, for each unit of 14C entering the structural compartment, between 0–9 (at 15°C) and 3.2 (at 30°C) units of 14C are lost by respiration. At 15°C in the dark, respiratory loss of 14C is initially from soluble and storage compartments; thereafter respiration of I4C occurs at the expense of structural material.
Effects of decreasing source/sink ratio in soybeans on photosynthesis, photorespiration, transpiration and yield
Authors: PEET M. M. , KRAMER P. J.
Published: April 2006

Abstract. Shading of all side leaflets of a determinate soybean cultivar during pod filling significantly increased rates of photosynthesis in the unshaded centre leaflets, compared to centre leaflets of controls. Higher rates were associated with both higher stomatal and mesophyll conductances, and were reversible within 2 days when shades were removed. These higher rates of photosynthesis were not associated with decreased percentage enhancement by low oxygen, indicating that treatment effects were probably not associated with changes in photorespiration relative to photosynthesis. Percentage enhancement did, however increase as the plants approached physiological maturity, chiefly because of a decrease in photosynthesis.

In spite of these increases in rates of photosynthesis seed weight per plant was decreased by 37% in plants with side leaflets shaded for the entire pod‐filling period and by 28% in plants shaded for only the second half of the period. In plants where shades were removed during the second half of pod filling seed yield was reduced by only 19% because shade removal delayed leaf senescence. The four treatments reduced yield by different mechanisms. Plants shaded continuously during pod filling produced fewer seeds than controls, but the weight per seed was similar. When shading was applied during the second half of pod fillings seed number was unchanged but weight per seed was significantly reduced. In contrast when shades were removed for the second half of pod filling, seed number remained similar to that of continuously shaded plants, but seed weight increased.

Although all shading treatments reduced yield, the reduction was not proportional to the 63% reduction in leaf area available for photosynthesis. This was because (1) photosynthetic rates in the centre leaflet of shaded plants were higher than rates in controls, (2) stem and lower surface photosynthesis in shaded leaf‐lets contributed to whole leaflet photosynthesis.
Hysteresis in the response of stomatal conductance in Pinus sylvestris L needles to light: observations and a hypothesis
Authors: NG P. A. P. , JARVIS P. G.
Published: April 2006

Abstract. The response of stomatal conductance in Pinus sylvestris L. to a sequence of progressively changed photon flux densities showed hysteresis when the direction of the sequence was reversed. Hysteresis was most evident when 1 h was allowed for stabilization at a temperature of 10°C and a leaf‐air vapour pressure difference of 0.5 kPa. The hysteresis was largely eliminated by a stabilization time of 2.5 h or a temperature of 20°C. Elimination of self shading also largely eliminated the hysteresis and resulted in light saturation of stomatal conductance at about 600 μE m−2 s−1 whereas with the normal grouping of fasicles light saturation was not achieved at 1750 μE m−2 s−1 even with bilateral illumination. Hysteresis was also eliminated by reduction in the maximum attainable conductance as a result of large leaf‐air vapour pressure differences (> 1.8 kPa) but reducing the ambient CO2 concentration to the compensation concentration or below had no effect on hysteresis. In addition to the hysteresis, there was a carry‐over effect of the previous treatment. When the direction of the sequence of photon flux densities was changed, stomatal conductance continued to change in the direction appropriate to the previous sequence for at least 1 h. The presence of a transportable chemical intermediate is postulated, the amount or activity of which would take some time to change after a change in photon flux density. The presence of such an intermediate could account for both the sluggishness of the stomata and the carry over effect. As a result of the sluggish behaviour and carryover, in the field stomatal conductance will tend to follow the general trend in photon flux density and will be very insensitive to short term fluctuations.
Ionic control of acid phosphatase activity in plant cell walls
Authors: NOAT GEORGES , CRASNIER MARTINE , RICARD JACQUES
Published: April 2006

Abstract.Purified acid phosphatase from sycamore cell walls is not activated by increasing the ionic strength of the reaction mixture. However activation occurs when the enzyme is bound to small cell wall fragments. The apparent activation of the bound enzyme by ions is paralleled by a decline of the substrate concentrationC1/2, that results in half of the maximum rate. Above ionic strengths of about 0.05 the bound and solubilized enzyme forms behave in the same manner. Titration of cell wall fragments at different ionic strengths show that the local pH, inside the cell wall fragments, is lower than the pH in bulk solution. These results are explained in the light of poly‐electrolyte theory. The negative charges of the cell walls generate an electrostatic potential that results in the attraction or repulsion of ions. The local concentration of organic phosphate (the substrate of the enzyme) is then lower than its concentration in bulk solution. This concentration difference explains that the value ofC1/2, or of the apparent Kmof the bound enzyme, is greater than the true Kmof the solubilized enzyme. Increasing the ionic strength tends to equalize bulk and local ion concentrations, and therefore apparently activates the bound enzyme.
Immunological studies on phosphoenolpyruvate carboxylase in Sedum species with crassulacean acid metabolism or C3 photosynthesis
Authors: MULLER D. , KLUGE M. , GRÖSCHEL‐STEWART U.
Published: April 2006

Abstract From Sedum morganianum, which is a plant species known to have constitutive crassulacean acid metabolism (CAM), phosphoenolpyruvate (PEP) carboxylase (E.C.4.1.1.31) has been extracted and purified by (NH4)2SC4 precipitation, ion exchange chromatography and gel electrophoresis. A specific antibody to this purified enzyme was obtained by immunization of a rabbit. This antibody was used to compare the antigen–antibody reaction of PEP‐carboxylases prepared from other Sedum species including constitutive, facultative and non‐CAM plants. The experiments revealed partial immunological indentity of PEP‐carboxylases obtained from the different sources.
The ionic relations of Porphyra purpurea(Roth) C.Ag. (Rhodophyta, Bangiales)
Authors: REED ROBERT H. , COLLINS JULIAN C.
Published: April 2006

Abstract Radioisotope equilibration techniques have been used to determine the intracellular concentration of K+, Na+ and Cl−, together with the unidirectional ion fluxes across the plasmalemma of Porphyra purpurea. Influx and efflux of 42K+, 24Na+ and 36C1− are biphasic, the rapid, initial uptake and loss of tracer from individual thalli being attributable to desorption from extracellular regions. Cellular fluxes are slower and monophasic, cells discriminating in favour of K+ and Cl− and against Na+. A comparison between the equilibrium potential of individual ion species and the measured membrane potential demonstrates that there is an active component of K+ and Cl− influx and Na+ efflux. ‘Active’ uptake and ‘passive’ loss of K+ and Cl− are reduced when plants are kept in darkness, suggesting that a fraction of the transport of K+ and Cl− may be due to ‘exchange diffusion’ (K+/K+ and Cl−/Cl−antiport).
The influence of environmental factors on apparent photosynthesis and respiration of the submersed macrophyte Elodea canadensis
Authors: SIMPSON P. S. , EATON J. W. , HARDWICK K.
Published: April 2006

Abstract Oxygen effects on apparent photosynthetic and dark respiratory O2 exchange rates of detached leaves of Elodea canadensis Michx. (Hydrocharitaceae) were determined over a range of conditions which the submersed plant is likely to experience in shallow water. Apparent photosynthesis is inhibited by O2 under all the experimental regimes of light, temperature, CO2 concentration and pH. This inhibition is not caused solely by an accelerated rate of dark respiration, and the observed variations in O2 inhibition are comparable to O2 effects on photosynthesis and photorespiration of terrestrial C3 plants. Percentage inhibition of apparent photosynthesis is enhanced by high O2 and also by low CO2. These results indicate that high O2, high pH and low CO2 conditions could cause major losses in photosynthetic activity under field conditions. This may account for some of the losses in biomass that are observed under still water conditions.
A study of the source of virus in the Pholem exudate appearing on leaves of Amscinckia infected with the beet curly top virus
Authors: ESAU KATHERINE , MAGYAROSY ANDREW C.
Published: April 2006

Abstract Leaves of Amsinckia douglasiana discharging phloem exudate after infection with the beet curly top virus (BCTV) were studied with the electron microscope. Infected tissue differed from the noninfected in having much hyperplastic phloem characterized by abnormally high proportion of sieve elements, scarcity of companion cells, degenerating parenchyma cells, and some unusually large intercellular spaces. Many spaces contained amorphous debris. Particles resembling BCTV were discernible within the debris. Such particles were encountered also in the debris trapped between stomatal guard cells. Since the phloem exudate excreted from leaves of BCTV‐infected plants contains virus particles, and since the virus is found extremely rarely in sieve elements, we suggest (1) that most of BCTV particles apparently released into intercellular spaces are derived from degenerating parenchyma cells in which the virus had multiplied; (2) that the exudate is derived from sieve elements of the hyper‐plastic phloem in which the normal functional control by companion cells is lacking; (3) that the exudate leaks from the nontransporting sieve elements through cell walls into intercellular spaces and carries the virus to the outside. Initially, stomata may serve as exits for the infectious exudate, but subsequently ruptures in the epidermis are involved.
Low temperature acclimation of root fatty acid composition, leaf water potential, gas exchange and growth of soybean seedlings
Authors: MARKHART ALBERT H. , PEET MARY M. , SIONIT NASSER , KRAMER PAUL J.
Published: April 2006

Abstract Root fatty acid composition, photosynthesis, leaf water potentials, stomatal resistances, leaf specific weights, and root: shoot ratios of soybean were measured in two temperature regimes.

Groups of soybean plants were grown in controlled chambers of the Duke University Phytotron under two thermoperiods. One group of the plants was grown from seed for 3 weeks in either 29/23°C or 17/11°C thermoperiods, and another group was grown for 2 weeks in 29/23°C and then transferred to the 17/11°C thermoperiod where it remained for 8 days. Broccoli was also grown in either 29/23°C or 17/11°C thermoperiods.

Soybean roots contained more unsaturated fatty acids than broccoli roots, although broccoli roots showed a larger increase in unsaturation than soybean roots with decreased temperature. The fatty acid unsaturation in the roots of soybean began to increase rapidly after the temperature regime was changed. The increase was in the new roots produced in the cold regime rather than in the pre‐existing roots.

The soybean leaf water and osmotic potentials decreased about 0.4 MPa, beginning one day after the transfer from 29/23°C to 17/11°C, but recovered significantly after 8 d.

Plants grown at 17/11 °C had lower rates of photosynthesis and adaxial stomatal resistances, but higher root: shoot ratios and specific leaf weights compared to plants grown at 29/23°C. Plants grown and maintained at 29/23°C showed a steady increase in photosynthetic rates over the 8‐d experimental period, whether rates were measured in 1 mol m−3 or 9 mol m−3 oxygen. Plants transferred to 17/11°C however maintained constant rates of photosynthesis at 1 mol m−3 O2, whereas at 9 mol m−3 rates declined for 2 d then were constant for the remaining 6 d of the experimental period.

These results suggest that changes in membrane fatty acid unsaturation is an important aspect of plant acclimation to chilling temperatures in terms of maintaining root permeability and water uptake. However, the degree of unsaturation is not a good indicator of differences in chilling tolerance among species. The apparent acclimation of photorespiration to a constant percentage of photosynthesis suggests a role of photorespiration in the plant.
Diurnal progressions in dry weight and short‐term plant growth studies
Authors: HUNT RODERICK
Published: April 2006

Abstract With the assistance of newly‐developed techniques involving splined regression curves, the direct analysis of dry weight increment in short‐term growth studies has become feasible. It is argued that, given certain mechanical improvements, these might replace some of the more conventional and lengthy types of growth study encountered in agronomy and in physiological plant ecology.
Measurements of photosynthesis in the field: utility of the CO2 depletion technique
Authors: EHLERINGER J. , COOK C. S.
Published: April 2006

Abstract A portable system for the rapid measurement of photosynthetic rates in the field is described and evaluated. The measurement of photosynthesis is based on extraction of volumes of air from a closed system cuvette containing a leaf over a set time interval. CO2 content of the gas volumes is determined with an infrared gas analyser, and photosynthetic rate is calculated from the cuvette CO2 concentration depletion rate. The magnitudes of sources of error with this system were analysed and methods of reducing the errors discussed. Representative examples of data obtainable with this technique are presented.

From the inlet and outlet ports of a cuvette for measurements of Sorghum bicolor dark respiration rates in the laboratory. We have modified their technique and report the utility of the CO2 depletion technique for measurements of photosynthesis on plants in the field, far from laboratory facilities. The technique is reliable and easy to operate in the field. A description of the technique, as well as an analysis of the sources of error and examples of the data which can be obtained with it are presented.
Change in sensitivity to far‐red irradiation on anthocyanin biosynthesis in red cabbage seedlings
Authors: SMALL CATHERINE J. , PECKET ROBERT C.
Published: April 2006

Abstract. Anthocyanin biosynthesis in red cabbage seedlings has been shown to be under a red/far‐red (R/FR) reversible phytochrome control. The ‘escape’ of anthocyanin synthesis from FR photoreversibility occurred between 12 and 20 h. However, a similarity exists between the escape curve and the temporal change in sensitivity to FR alone, which suggests that some of the ‘escape’ may be due to the promotive effect of FR. Some escape times may not therefore be a true measure of the duration of Pfr action, contrary to the traditional view.
Droopy: a wilty mutant of potato deficient in abscisic acid
Authors: QUARRIE S. A.
Published: April 2006

Abstract. Droopy mutant of potato (Solanum tubero‐sum L., group Pliureja) wilts because of excessive stomatal opening (Waggoner & Simmonds, 1966). Progeny of the cross between potato clones C.P.C. 4461 and C.P.C. 4463 showed characteristics similar to those of the original droopy potato. These plants wilted at high vapour pressure deficit and their stomatal conductances in the light and the dark were higher than those of normal plants. Conductances were reduced by applied abscisic acid (ABA), but stomata remained partially open even when guard cells were plasmolysed. Leaves of droopy plants accumulated very little ABA when water‐stressed.
Differential changes in the electron transport properties of thylakoid membranes during aging of attached and detached leaves, and of isolated chloroplasts
Authors: MISRA A. N. , BISWAL U. C.
Published: April 2006

Abstract. Aging of chloroplasts both in vivo and in vitro causes a considerable loss in the 2,6‐dichlorophenol indophenol (DCPIP)‐Hill reaction with water as electron donor. The loss can be reduced by exogenous electron donors like diphenyl carbazide (DPC). suggestive of aging‐induced damage of the oxygen evolving system. Aging also brings about a considerable loss in methylviologen (MV) reduction mediated by Photosystem I (PS I) of chloroplasts with an ascorbate‐DCPIP couple as the electron donating system.

The loss in the electron transport ability of the plastids is faster during in vitro compared to in vivo aging of the chloroplasts.

Light protects the photo‐electron transport ability of chloroplasts during aging of intact leaves in contrast to its action during aging of the isolated organelles.
Protein accumulation in developing endosperm of a high‐protein line of Triticum dicoccoides
Authors: PARKER MARY L.
Published: April 2006

Abstract. Endosperm tissue from developing grains of a line of wheat (Triticum dicoccoides) which accumulates up to 30% protein in the mature grain, was examined by electron microscopy to establish the ontogeny of the storage protein bodies. Ultrastructural evidence suggests that storage proteins of wheat may be transported from their site of synthesis on the rough endoplasmic reticulum (ER) to protein bodies by two different routes within the endomembrane system. The first route, which probably functions throughout protein deposition, involves the transport of protein from the cisternal rough ER to the protein vacuoles via the Golgi apparatus. The second route, observed 20 d after anthesis, appears to lead directly from dilated regions of the rough ER to protein vacuoles, bypassing the dictyosomes. Phytin inclusions are found in protein vacuoles of starchy endosperm cells adjacent to the aleurone layer of developing grain.
Changes in tissue protein pattern in relation to auxin induction of DNA synthesis
Authors: MELANSON D. , TREWAVAS A. J.
Published: April 2006

Abstract. When artichoke tuber tissue was cultured in mineral salts, the induction of DNA synthesis and subsequent cell division was dependent upon the presence of auxin in the incubation medium. Evidence is provided that an obligatory set of metabolic events precedes auxin‐induced DNA synthesis, and previous work has associated these with protein synthesis. As a consequence the auxin‐induced changes in nuclear and cytoplasmic proteins have been investigated. Using 2D gel electrophoresis, qualitative alterations in nuclear non‐histone proteins have been detected from the earliest treatment times with auxin. These changes were progressive, starting with four novel proteins after 3 h auxin treatment and ending with about forty when DNA synthesis commences some 18–21 h later. Qualitative alterations in phosphorylated nuclear proteins due to auxin treatment were only detectable when DNA synthesis commenced. In contrast, few qualitative alterations in cytoplasmic proteins were detectable, with the major change being in phosphorylated proteins at the onset of DNA synthesis.

A possible model of auxin action is outlined which involves sequential and progressive changes in the synthesis of nuclear proteins and the control of gene expression eventually leading to DNA synthesis.
Stomatal responses of pearl millet (Pennisetum americanum [L.] Leeke) to leaf water status and environmental factors in the field
Authors: HENSON I. E. , ALAGARSWAMY G. , BIDINGER F. R. , MAHALAKSHMI V.
Published: April 2006

Abstract. Factors affecting stomatal conductance (g1) of pearl millet (Pennisetum americanum [L.] Leeke), cultivar BJ 104, were examined in the field in India during the dry season.

Diurnal changes in g1 were evaluated for upper expanded leaves at flowering on two occasions using plants subjected to varying degrees of water stress. Except for the most severely stressed treatment, diurnal changes in g1 closely matched changes in irradiance (I), the promotive effect of which largely overcame opposing influences on g1 of increasing atmospheric vapour pressure deficit, and decreasing leaf water and turgor potentials (Ψ, Ψp).

Two main effects of water stress on g1 were evident: (i) a decrease in the amplitude of the mid‐day peak in g1, and (ii) a decrease in the time over which high g1 was maintained, resulting in early (mid‐day) closure and hysteresis in the relationship between g1 and I.

Leaf conductance was greatest for upper leaves and decreased down the canopy. At equivalent depths in the canopy g1 was higher in flowering than in photoperiodically‐retarded plants of the same age. The magnitude of water stress‐induced stomatal closure increased down the plant, and was more marked in retarded than in flowering plants.

Within individual stress treatments Ψ of upper leaves decreased linearly as transpiration flux increased. It is concluded that stomatal behaviour of upper leaves of pearl millet at flowering largely operates to maximize assimilation rather than to minimize water loss.
Transport of gases into leaves
Authors: CSIRO R. LEUNING
Published: April 2006

Abstract. Transport of gases between the intercellular spaces of plant leaves and the surrounding air is analysed in terms of multicomponent collision processes through an isothermal, porous septum. Interaction of diffusing species with each other and with the pore walls is described using a modified Stefan–Maxwell equation and an equation relating the pressure gradient to the sum of the diffusive fluxes, weighted by their appropriate Knudsen diffusivities. Viscous How arising from an excess pressure within the leaf is also considered.

Equations are derived which describe the flux densities of water vapour and CO2 through the stomata. The analysis is general and is applicable to trace gases other than CO2. A simple conductance is defined for water vapour to relate the flux and mol fraction difference across the stomata, viz. Nw=−gw, δxw/xa. A simple conductance cannot be defined for CO2 because the flux of water vapour has a significant influence on the CO2 gradient. The equation derived for the intercellular mol fraction of CO2 is in terms of the fluxes of CO2and water vapour and represents a ‘large‐pore’ (d > μm) approximation which requires no information about stomalal geometry. Analogous equations are developed for transfer of gases through the leaf boundary layer. Sample calculations are presented to illustrate the effect of neglecting the interaction of water vapour and CO2 on the calculated intercellular and surface concentrations of CO2. Equations for computing water vapour and CO2 flux densities from leaf chamber measurements are also presented.
Calcium transport and ATPase activity in a microsomal vesicle fraction from corn roots
Authors: ZOCCHI GRAZIANO , HANSON JOHN B.
Published: April 2006

Abstract. An investigation has been made of methods for isolating membrane vesicles from corn (Zea mays L.) roots active in calcium transport and K+‐stimulated ATPase. Pretreating and grinding the roots at room temperature with EGTA and fusicoccin increases basal ATPase activity. Improvement in Ca2+ uptake requires isolation of a scaled vesicle fraction by the method of Sze(1980). Sorbitol is superior to sucrose as an osmoticant. The pH optimum for Ca2+ uptake is 7.5. whereas that for associated ATPase activity is 6.5. Calmodulin strongly stimulates Ca2+ uptake in a process little affected by uncouplers and ATPase inhibitors, but blocked by chlorpromazine. Fusicoccin gives less stimulation of Ca2+ uptake which is sensitive to uncouplers, and is dependent upon isolation with fusicoccin present. It appears that the sealed vesicle fraction may possess two Ca2+ transport systems: a calmodulin‐activated Ca2+‐transporting ATPase, and a Ca2+/H+ antiport coupled through the protonmotive force to a fusicoccin‐stimulated H+‐ATPase.
An alternative method for analysing pressure‐volume curves produced with the pressure chamber
Authors: SINCLAIR R. , VENABLES W. N.
Published: April 2006

Abstract. An equation is derived relating tissue water potential to relative water content. This equation may be used to lit a single curve to a set of data such as the standard pressure volume measurements made with a pressure chamber. From such a single curve fitting operation, estimates of the parameters involved may be found, and this allows calculation of such quantities as bulk modulus of elasticity, osmotic potential at full turgor and at the turgor loss point, pressure potential, and the weight of symplastic water. The method of analysis has several advantages, which are illustrated using pressure chamber data obtained from leaves of Lombardy poplar, Populus nigra L. ‘italica’.
Associations between plant production and some physiological components of drought resistance in wheat
Authors: BLUM A. , MAYER J. , GOZLAN G.
Published: April 2006

Abstract. Drought resistance in terms of plant production under conditions of drought stress was previously defined for several spring wheat (Triticum aestivum L.) varieties. Four varieties, differing in their drought resistance by this definition, were compared in their physiological responses to water stress, as induced by polyethylene glycol 6000 in the growth medium.

Drought resistance was associated with osmotic adjustment, total root mass production under stress, maintenance of some stomatal permeability under stress, and maintenance of turgor at a given level of drought stress, by either osmotic adjustment or elevated plant water potential.

Drought resistance was not associated, in this experiment, with plant top growth under stress or non‐stress conditions, maximum leaf area per plant, plant transpiration, and total root mass production under non‐stress conditions.
Time course of signal transduction in phytochrome‐mediated anthocyanin synthesis in mustard cotyledons
Authors: SCHMIDT R. , MOHR H.
Published: April 2006

Abstract. The effectiveness of phytochrome (Pfr) in mediating anthocyanin synthesis in epidermal cells of mustard (Sinupis alba L.) cotyledons is strongly increased by a light pretreatment of the seedling prior to competence (Mohr et al., 1979; Johnson, 1980). Here we test the hypothesis that the observed ‘sensitivity amplification’ is related to a change in the time course of signal transduction from phytochrome to the responsive cell function. It was found that the time course of escape from photoreversibility—considered to reflect the time course of signal transduction—is not changed by a light pretreatment, although the rate of signal transduction increases with age and depends strongly on the level of Pfr.
Movement of fluorescein into isolated caryopses of wheat and barley
Authors: COOK H. , OPARKA K. J.
Published: April 2006

Abstract. The movement of fluorescein, a symplastic fluorescent tracer, into isolated caryopses of wheat and barley is described. The dye followed the pathway to the endosperm which has been proposed previously from anatomical studies, namely a movement from the phloem, through cells of the pigment strand and nucellar projection, followed by a radial spread of the dye from the endosperm cavity into the starchy endosperm. By contrast, the fluorochromes calcofluor white M2R and ANS remained confined to the apoplast and failed to cross the ‘xylem discontinuity’ at the base of the caryopses.
A multichannel microcomputer‐based system for continuously measuring and recording ion activities of uptake solutions during ion absorption by roots of intact plants
Authors: GLASS ANTHONY D. M. , SIDDIQI M. YAEESH , DEANE‐DRUMMOND CELIA E.
Published: April 2006

Abstract. A microcomputer‐based system for the measurement of changes of ion activity (H+, NO3−, K+) in the uptake solutions during ion absorption by roots of intact plants is described. Ion activities are measured by means of ion‐specific electrodes in a multichannel programmable voltmeter (data acquisition/control unit) which is activated by means of a microcomputer. Incoming data are stored digitally on tape cassettes or floppy discs via the microcomputer. The speed of sampling and large numbers of samples which can be simultaneously measured and recorded make this an extremely versatile system which might be employed for measuring and recording any number of analogue voltage signals.
Studies on ethylene binding by cell‐free preparations from cotyledons of Phaseolus vulgaris L.: subcellular localization
Authors: EVANS D. E. , BENGOCHEA T. , CAIRNS A. J. , DODDS J. H. , HALL M. A.
Published: April 2006

Abstract. Studies on the subcellular location of ethylene binding activity from developing cotyledons of Phaseolus vulgaris L. are described. Binding activity has been shown to be predominantly membrane bound. When separated by rate‐zonal centrifugation more than 70% of this activity was of low sedimentation rate. The slowly sedimenting band of activity was further fractionated into three bands by isopycnic density gradient centrifugation. The three bands occur at sucrose densities of 1.125 g cm−3, 1.155 g cm−3 and 1.175 g cm−3, corresponding to the distribution of putative marker enzymes for the cell endomembrane system and to protein body membranes. Further circumstantial evidence was obtained by electron microscopy and sucrose step gradient centrifugation.