bluuebunny/crossref_metadata_2025_split huggingface dataset:
STOMATAL DEVELOPMENT AND SEASONAL CHANGES IN DIFFUSIVE RESISTANCE OF PRIMARY AND REGROWTH FOLIAGE OF RED OAK (QUERCUS RUBRA L.) AND RED MAPLE (ACER RUBRUM L.)
Authors: TURNER N. C. , HEICHEL G. H. 
Published: May 2006

SUMMARYFrom foliar emergence until senescence, the abaxial diffusive resistance of primary foliage, and of regrowth foliage produced after defoliation, was measured at several irradiances with a ventilated diffusion porometer. Concurrent measurements were made of stomatal dimensions and frequency, including scanning electron‐microscopy, and of leaf area. The diffusive resistance of newly emerged primary leaves was about 15 s cm−1 in maple and 20 s cm−1 in oak at all irradiances. The stomata became sensitive to light within 2 weeks of emergence, oak being slightly earlier than maple. Thereafter, the resistance at an irradiance of 0.5 cal cm−2 min−1 fell to a seasonal minimum of 3 s cm−1 in oak and 5–7 s cm−1 somewhat later in maple. With the onset of senescence, and earlier in maple than in oak, the resistance of primary leaves in bright light increased and the stomata became less sensitive to light. As leaf colour changed from green to red or brown, the resistance increased to about 60 to 80 s cm−1 in both oak and maple.The resistance of regrowth foliage that emerged in July was about 5–7 s cm−1 in maple and 12–15 s cm−1 in oak, thus lower than that in newly emerged primary foliage. Within a week of emergence, 3 weeks sooner than with primary foliage, the resistance at 0.5 cal cm−2 min−1 fell to about 3 s cm−1 in both species. During July and August, the resistance of regrowth foliage of maple was about one‐third that of the primary foliage, but about the same in both regrowth and primary foliage of oak.At the time of regrowth leaf emergence (July), the mean temperature was 10° C higher than that at primary leaf emergence (May), but in both species the initial rates of leaf expansion were similar. Although the areas of individual primary leaves were about twice those of regrowth leaves, the stomatal frequencies and dimensions were similar. Maximum stomatal length was achieved before the leaves were fully expanded and before the stomata became responsive to light. The development of light sensitivity was apparently independent of leaf expansion and the attainment of final stomatal size, but strongly dependent on environmental regulation of stomatal metabolism.
MEVALONATE‐ACTIVATING ENZYMES IN WHEAT ETIOPLASTS
Authors: COOKE R. J. 
Published: May 2006

SUMMARY(2‐14C)‐MVA (mevalonic acid) is metabolized to two major products by sonicated preparations of purified intact etioplasts isolated from wheat leaves. These metabolites have been identified by their RF values and from the products of their hydrolysis as MVAP and MVAPP (mevalonate‐5‐phosphate and mevalonate‐5‐pyrophosphate, respectively). Intact preparations of etioplasts are essentially impermeable to (2‐14C)‐MVA, even after a red light irradiation.
RADIOAUTOGRAPHY OF MYO‐INOSITOL IN CULTURED FRAXINUS CALLUS
Authors: WOLTER KARL E. , MURMANIS LIDIJA 
Published: May 2006

SUMMARYRadioautographs by light and electron microscopy of callus cells of green ash (Fraxinus pennsylvanica Marsh.) that had been fed low levels of the growth factor 3H myo‐inositol indicated an almost exclusive incorporation of the label into the cytoplasmic constituents. These results contrast with those from most other studies of incorporation in higher plants. The incorporation here of myo‐inositol suggests that its prime function is the synthesis of cytoplasmic membrane systems of the cell rather than in the polysaccharide component of the primary wall.
EFFECTS OF AQUEOUS SULPHUR DIOXIDE ON CHLOROPHYLL DESTRUCTION IN PINUS CONTORTA
Authors: MALHOTRA S. S. 
Published: May 2006

SUMMARYThe effects of aqueous SO2 on chlorophyll breakdown in lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) were determined under laboratory conditions. Aqueous SO2 concentrations ranging from 100 to 500 ppm resulted in a sharp decrease in total chlorophyll content. Chlorophyll a was more sensitive to SO2 than chlorophyll b. Quantitative determinations of various pigments suggested that's SO2 causes the conversion of chlorophyll a into phaeophytin a (100–500 ppm SO2) and chlorophyll b into chlorophyllide b (10–50 ppm SO2). The suggested conversion of chlorophyll into chlorophyllide induced by SO2 was supported by increased activity of pine needle chlorophyllase at low aqueous SO2 concentrations (10–50 ppm). The breakdown of chlorophyll molecules by SO2 as measured by loss of Mg++ and total chlorophyll was accompanied by a decreased ability of pine needles to photosynthesize H14CO3. The effect of SO2 on pigment breakdown and rate of photosynthesis was due mostly to the specific direct actions of SO2 and was not a function of increased acidity.
SULPHUR DIOXIDE METABOLISM IN SOY‐BEAN, GLYCINE MAX VAR. BILOXI
Authors: GARSED S. G. , READ D. J. 
Published: May 2006

SUMMARYFirst‐trifoliate leaves of four‐leaved soybean plants were exposed to 35SO2 in the light or dark, and the uptake and translocation of radioactivity measured. Nearly four times more 35SO2 was taken up in the light (stomata open) than in the dark (stomata closed) but approximately 50% of the radioactivity was leached from the leaf surface in the dark compared with 5% in the light. A greater proportion of the source‐leaf radioactivity was translocated in the dark but, in absolute terms, the quantity of radioactivity moved was less. Radioactive products were found in all parts of the plant after exposure in both light and dark. The expanding trifoliate leaf contained the greatest concentration of translocated radioactivity in both cases. Light and dark pre‐ and post‐treatments had little effect on uptake of 35SO2 or translocation of the products. 35SO42− was detected in the nutrient solution within 1 h of exposure of leaves to 35SO2.
THE EFFECT OF L‐ARGININE ON THE GROWTH OF HETEROTROPHIC CULTURES OF THE EMERSON STRAIN OF CHLORELLA
Authors: THINH L. V. , GRIFFITHS D. J. 
Published: May 2006

SUMMARYThe ability of L‐arginine to stimulate autospore production in heterotrophic cultures of the Emerson strain of Chlorella is reversed by chloramphenicol. The antibiotic does not affect the uptake of glucose, neither does it alter significantly the pattern of incorporation of radioactivity from 14C glucose into the major fractions of arginine‐treated cultures. The inhibitory effect of the antibiotic is largely restricted to those aspects of development which specifically respond to arginine. Thus, the stimulation of DNA synthesis by arginine is strongly reversed by chloramphenicol suggesting the involvement of some chloroplast‐centered event. Chloramphenicol does not inhibit the uptake of arginine but affects the subsequent metabolism of the amino acid. It is concluded that addition of arginine may lead to the synthesis in the chloroplast of specific polypeptides necessary for nucleic acid synthesis and cell division.
ULTRASTRUCTURAL STUDIES IN THE BROWN ALGA ECTOCARPUS IN CULTURE: AGEING*
Authors: OLIVEIRA LUIS , BISALPUTRA THANA 
Published: May 2006

SUMMARYUltrastructural changes associated with ageing of the vegetative sporophytic cells of Ecto‐carpus are described. Nuclei, endoplasmic reticulum and dictyosomes become reduced or disappear; mitochondria are also much affected. Of all cell organelles, plastids display the most striking alterations. These include the formation and release into the cytoplasm of electron‐dense material, probably of lipid nature, and the budding off of portions of the plastids. The cytoplasm, congested with a variety of inclusions, shows toward the end of the ageing process the first signs of autolysis (rupture of the tonoplast). Conspicuous wall ingrowths are also formed along the cross and end walls of the cells. Ingrowths that occur at the cross walls do not seem to disrupt plasmodesmatal continuity. The maintenance of symplast continuity is believed to be significant to the progress of the ageing process. The present findings are discussed in relation to available data obtained from other plant studies.
MYCORRHIZAL ENDOGONACEAE IN A NEW ZEALAND FOREST
Authors: JOHNSON P. N. 
Published: May 2006

SUMMARYMost vascular plants and some liverworts in a New Zealand coniferous‐dicotyledonous forest harboured typical vesicular‐arbuscular endophytes, Rhizophagus tenuis or mixtures of the two. At least nine sporing fungi were present but non‐sporing races probably predominated. Spores were present in variable densities (2–17 × 103 1−1) in forest soils but their distribution was not obviously related to that of host plants.In inoculation experiments, fungi had a wide host range and, in terms of growth response, hosts showed no clear preferences for particular endophytes. There was some indication of fungi being specific to soil type.Many tree seedlings begin growth perched on rocks or logs and Rhizophagus tenuis is a pioneer endophyte there.
THE BREEDING SYSTEM OF PONTEDERIA ROTUNDIFOLIA L., A TRISTYLOUS SPECIES
Authors: BARRETT S. C. H. 
Published: May 2006

SUMMARYPopulations of Pontederia rotundifolia in the Lower Amazon and Costa Rica are tristylous. A strong pollen trimorphism is associated with differences in stamen and style length in the three floral forms. The results of a controlled pollination programme with thirty individual plants of P. rotundifolia demonstrate that floral trimorphism is accompanied by a physiological self‐incompatibility system typical of many heterostylous plants. Legitimate pollinations are considerably more productive of seed than illegitimate pollinations. Individual plants exhibit differences in the strength of self‐incompatibility, but in general, short‐styled plants possess the strongest self‐incompatibility, long‐styled plants are intermediate and mid‐styled plants have the weakest self‐incompatibility. Large differences in the strength of self‐incompatibility are expressed in self‐pollinations with pollen from the two anther levels of each style form.Natural populations of P. rotundifolia often contain only a single style form or contain unequal proportions of style forms. Seed set, resulting from moderate self‐compatibility, occurred in a Cosra Rican population that contained only short‐styled plants. Two populations associated with rice cultivation in the Lower Amazon contained equal proportions of the three style forms. The seed set of the three forms within these populations was similar. The floral trimorphism and breeding system of P. rotundifolia are compared with those of the related P. cordata and Eichhornia crassipes.
STUDIES OF MALATE FORMATION IN ‘ISOLATED’ GUARD CELLS
Authors: TRAVIS A. J. , MANSFIELD T. A. 
Published: May 2006

SUMMARYAfter they had been ‘isolated’ by a low pH treatment which destroyed all the other cells of the epidermis, stomatal guard cells retained the capacity to produce malate when presented with fusicoccin as a stimulus to opening. For a given level of stomatal opening, the amount of malate in epidermis with isolated stomata was practically the same as in intact epidermis. It is concluded that malate transport to and from the subsidiary cells is not an essential part of the stomatal mechanism. Changes in CO2 concentration over the range 0–100 ppm affected neither stomatal aperture nor malate levels in epidermis of Commelina communis. This suggests that carboxylation of phosphenolpyruvate plays no major part in the formation of malate in guard cells.
GAS EXCHANGE AND ENZYME ACTIVITY DURING LEAF EXPANSION IN PHASEOLUS VULGARIS L.
Authors: O'TOOLE J. C. , LUDFORD P. M. , OZBUN J. L. 
Published: May 2006

SUMMARYNet photosynthesis, transpiration, boundary layer plus stomatal resistance to CO2 diffusion, and CO2 compensation point were monitored in the central leaflet of expanding first trifoliate leaves of Phaseolus vulgaris L. Simultaneously, the activities of three enzymes related to net photosynthesis, photorespiration and dark respiration were measured. Net photosynthesis rate and ribulose 1,5‐diphosphate carboxylase activity increased with leaflet expansion, reaching peaks just prior to full expansion. Concurrently, boundary layer plus stomatal resistance, CO2 compensation point and malate dehydrogenase activity decreased, reaching lowest values at full leaflet expansion.Shortly after peak photosynthetic activity was reached all trends reversed, as the physiological activity of the first trifoliate leaf of this determinate type bean plant changed to that characterized by a senescing leaf.
A FAST‐READING VISCOUS FLOW LEAF POROMETER
Authors: SHIMSHI D. 
Published: May 2006

SUMMARYA field porometer is described for measuring the permeability of amphistomatous leaves. The apparatus is a light (2.8 kg) portable version of Gregory and Pearse's porometer, which enables the operator to read the permeability immediately after clamping the leaf, thus obviating changes of stomatal aperture during measurements. The apparatus has two sensitivity ranges; details on its construction and calibration are presented.
THE DEVELOPMENT OF OEDOCEPHALUM‐TYPE CONIDIA IN THE FUNGI CUNNINGHAMELLA ECHINULATA AND FOMES ANNOSUS
Authors: COOK BERYL E. 
Published: May 2006

SUMMARY Oedocephalum‐type conidiophores of the zygomycete Cunninghamella echinulata, and the basidiomycete Fomes annosus, studied by light and electron microscopy, developed in similar ways: vesicles were present in the cytoplasm of all regions of growth and development, initiation and growth of the conidium stalks and conidia were synchronous and conidia were delimited by occlusion of the stalk by a thickened wall layer. However, in Cunninghamella, conidia were produced holoblastically while, in Fomes, they were formed enteroblastically.
GLUTAMINE SYNTHETASE AND NITROGENASE ACTIVITY IN THE BLUE‐GREEN ALGA ANABAENA CYLINDRICA
Authors: ROWELL P. , ENTICOTT S. , STEWART W. D. P. 
Published: May 2006

SummaryOn adding NH4+ to nitrogen‐fixing cultures of Anabaena cylindrica, the glutamine pool of the intact filament increases within seconds. Nitrogenase activity and then glutamine synthetase activity decline. There are no changes in the activities of glutamate‐aspartate aminotrans‐ferase, or in the pools of alanine, glycine and aspartate during this period. Nitrogenase activity is usually inversely related to the size of the glutamine pool and shows little correlation with glutamine synthetase activity per se. There is no evidence of adenylylation or dead‐enylylation of glutamine synthetase (snake venom phosphodiesterase has no effect on activity, there is no serological homogeneity with the Escherichia coli enzyme which shows a covalent modification; the ratio of biosynthetic: transferase activity does not change markedly on the addition of NH4+ and the kinetics of decrease in glutamine synthetase activity are not consistent with adenylylation of the enzyme).Feed‐back inhibition occurs, with alanine and glycine being particularly effective inhibitors and with some inhibition occurring with AMP, carbamoyl phosphate and aspartate. Histidine, lysine, ornithine, citrulline and arginine were non‐inhibitory at the concentrations used. There is no evidence of inhibition of glutamine synthetase by glutamine. The addition of azaserine inhibits glutamine uptake by intact filaments and reduces the subsequent conversion of glutamine to glutamate within the filament by 77%. Such results are consistent with the operation of the glutamine synthetase‐glutamate synthase pathway in Anabaena cylindrica.
DENSITY LABELLING DURING MICROBODY DEVELOPMENT IN COTYLEDONS
Authors: BROWN RICHARD H. , MERRETT MICHAEL J. 
Published: May 2006

SummaryDuring the development of pumpkin (Cucurbita pepo) cotyledons peroxisomal development was dissociated completely from glyoxysomal decline by keeping seedlings in darkness for up to 20 days; glycollate oxidase activity resulting from illumination then occurred after complete decay of isocitrate lyase. During cotyledon development a peak of phosphoryl‐choline glyceride transferase activity preceded maximal development of glyoxysomes while a second peak of activity occurred after illumination but before maximal development of peroxisomes. When dark‐grown cotyledons were illuminated on transfer to 2H2O and micro‐bodies isolated by gradient centrifugation, peroxisomes were separated from glyoxysomes because of their greater equilibrium density. The observed density shift for peroxisomes suggests that they arise by de novo synthesis rather than by modification of glyoxysomes.
CONTROL OF POLYPHENOL OXIDASE (O‐DIPHENOLASE) IN DE‐EMBRYONATED BARLEY AND WHEAT GRAINS
Authors: JENNINGS P. H. , DUFFUS C. M. 
Published: May 2006

SummaryDifferent control mechanisms were shown to exist which affected the level of o‐diphenolase (o‐Diphenol: Oxygen oxidoreductase, E.C.I. 10.3.1) activity in extracts of two barley cultivars and one wheat cultivar. Both the increase in o‐diphenolase activity which occurs in Kleiber wheat during half‐grain incubation and the activity promoted by gibberellic acid (GA3) were dependent on protein synthesis and could be inhibited by cycloheximide and abscisic acid respectively. Incubation with GA3 lowered o‐diphenolase activity in the barley, Nakta, which was not due to GA3 promoted protease activity. The role of protein synthesis and protease activity in controlling the levels of detectable o‐diphenolase activity is discussed. GA3 caused a direct, stimulatory effect on o‐diphenolase activity extracted from both Kleiber and Nakta when the hormone was added to the assay mixture.
SHIFTS IN PHOTOSYNTHETIC CARBON LABELLING PATTERN BY ETIOLATED RICE (ORYZA SATIVA L.) SEEDLINGS DURING GREENING
Authors: RAGHAVENDRA A. S. , DAS V. S. R. 
Published: May 2006

SummaryThe carbon assimilation pattern in light by dark‐grown rice (Oryza sativa) seedlings was studied during greening. After exposure of etiolated seedlings to light their capacity to synthesize the C4‐acids, malate and aspartate, increased for 12 h. The labelling of 3‐phospho‐glycerate, sugar phosphates, sucrose and insolubles, did not increase until after 12 h. Thereafter a continuous steep increase in synthesis of Calvin cycle intermediates, but not of C4‐acids, recurred. The levels of carboxylating enzymes (phosphoenolpyruvate and ribulose diphosphate carboxylases) in the seedlings correlated positively with the appearance of label in C4 acids and in Calvin cycle compounds. We suggest that a β‐carboxylation mechanism was activated immediately on illumination but was persistent for only 12 h. After an 8‐h lag period following illumination, the Calvin cycle began to operate and continued during further growth of seedlings in light.
UPPER CRITICAL LEVELS OF TOXIC ELEMENTS IN PLANTS
Authors: BECKETT H. T. , DAVIS R. D. 
Published: May 2006

SummaryThis study examined the effect of Cu, Ni, Zn or Cd in the leaves and shoots of young barley on their yield of dry matter.As expected, the yield of dry matter, or the uptake of heavy metals from a given solution, varies considerably with growing conditions. However, the minimum concentrations of these elements in the plant tissue that was necessary before the yield of dry matter was reduced by their toxic effects (‘upper critical level’) proved to be independent of growing conditions varied enough for the control plants to have required 14–31 days to reach the five‐leaf stage, and for the weights of the control plants to have ranged from 76 to 214 mg.This being so it is suggested that if young barley plants were used to monitor accumulations of heavy metals in the soil environment, the quantity would provide a good measure of the hazard of any accumulation relative to the onset of toxicity, where To and Tc are standard values for the background (unpolluted) and the upper critical level of the element in plant tissue, and Tits level in a test crop. This reduces to [m. Log10T/n] and if T is measured in ppm of dry matter, m and n are approximately,

image

A graph of Relative Hazard against tissue concentration is presented.
STUDIES ON INSECT‐FREE GROWTH, DEVELOPMENT AND NITRATE‐ASSIMILATING ENZYMES OF DROSERA ALICIAE HAMET*
Authors: SMALL G. C. , ONRAËT ANGELA , GRIERSON D. S. , REYNOLDS GAYNOR 
Published: May 2006

SummaryThe carnivorous plant, Drosera aliciae, cultivated insect‐free from seed showed better growth with nitrogen as NH4Cl and NH4NO3 than with NaNO3. Highest yields of NaNO3‐treated plants were obtained at pH 4.0 and 4.5 whereas with NH4Cl and NH4NO3 yields increased with increasing pH. Plants grown on a nitrogen‐free medium but fed cheese were little affected by pH. Plants flowered and produced viable seeds in all treatments. The enzymes, nitrate reductase, nitrite reductase, a peroxidase capable of reducing nitrate, gluta‐mate dehydrogenase, glutamate synthase and glutamine synthetase were demonstrated in cell‐free extracts of roots and leaves. Enzyme levels in ammonium, cheese and nitrate‐fed plants were compared.
POTASSIUM EFFLUX BY LICHEN THALLI FOLLOWING EXPOSURE TO AQUEOUS SULPHUR DIOXIDE*
Authors: PUCKETT K. J. , TOMASSINI F. D. , NIEBOERJ E. , RICHARDSON D. H. S. 
Published: May 2006

SummaryPotassium efflux is a useful experimental quantity for assessing damage to lichens exposed to SO2. This SO2‐induced K+ efflux is biphasic in response to increasing concentrations of aqueous SO2. The first phase can be extrapolated to identify the SO2 concentration at which no K+ release occurred above the control values. This threshold concentration was used to determine the relative sensitivities of various lichen species. Good agreement was observed between the total K+ lost and the reduction in the total photosynthetic 14C‐fixation rates. The magnitude of the SO2‐induced K+ efflux indicated that release occurred from intra‐cellular sources. The kinetics of the release process and the effects of SO2 on membrane integrity are discussed.
A MODEL FOR THE RELATIONSHIP BETWEEN GASEOUS AND AQUEOUS CONCENTRATIONS OF SULPHUR DIOXIDE IN LICHEN EXPOSURE STUDIES*
Authors: NIEBOER E. , TOMASSINI F. D. , PUCKETT K. J. , RICHARDSON D. H. S. 
Published: May 2006

SummaryThe linear relationship, ppm SO2 (wt/wt, aqueous) = 10.3 , is evaluated experimentally for the gaseous concentration range 0–5 ppm and is confirmed theoretically. It is suggested that this physicochemical equilibrium expression is applicable to lichen exposure studies because lichens are poikilohydrous plants.
NUMERICAL TAXONOMIC STUDIES ON SPECIES IN ALLIUM SUBGENUS RHIZIRIDEUM
Authors: EL‐GADI A. , ELKINGTON T. T. 
Published: May 2006

SummaryNumerical taxonomic studies have been carried out on fifteen operational taxonomic units (O.T.U.'s) belonging to Allium subgenus Rhizirideum. The data comprise measurements and observations of forty‐nine morphological and cytological characters and thirty‐eight chemical characters which are volatiles detected by gas liquid chromatography of direct vapour samples and mainly identified as sulphides. The CLASP program has been used to analyse the data. Classifications derived from hierarchical cluster analyses and principal co‐ordinates analyses are presented as dendrograms and vector plots respectively, the latter with the minimum spanning trees added. Classifications produced by analysis of the morphological and cytological characters and chemical characters are compared both with one another and with those produced by analysis of all characters.The main groups distinguished in the analyses are (a) A. cepa, A. cepa cv. Shallot, A. galanthum and A. fistulosum; (b) O.T.U.'s belonging to A. schoenoprasum; (c) A. senescens, A. senescens var. glaucum, A. montanum and A. albidum; (d) A. tuberosum and A. ramosum (e) A. farreri. These groups correspond with biosystematic groupings suggested by hybridization studies. They are also compared with existing sectional classifications of the genus.
DIURNAL VARIATIONS IN ENDOGENOUS ETHYLENE LEVELS IN PLANTS
Authors: KAPUYA J. A. , HALL M. A. 
Published: May 2006

SUMMARYDiurnal variations in endogenous ethylene levels occur in Vicia faba, Kalanchoe daigremontana and Caltha polypetala under both long and short days, higher levels being present under the former. The significance of these variations and the factors involved in their causation are discussed.