bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethylene loss from the gas phase of container‐seal systems
Authors: NELSON NEIL D. , ISEBRANDS J. G. , RIETVELD WILLIS J.
Published: April 2006

Ethylene losses from the gas phase of various container‐seal systems were studied to develop acceptable methods for containing ethylene during experiments. Ethylene at an initial amount of 104 μI I‐1 was stored in glass vials at near atmospheric pressure for 20 h at 25–27°C and at 35% relative humidity external to the vials. Crimped serum vials sealed with saturated (NH4)2SO4 solution, neoprene rubber septa, nitrile rubber (Hycar) septa, butyl rubber septa, and brown translucent silicone rubber septa lost ethylene at the rate of 1.8, 10.2, 16.2, 16.5, and 40.2 nl m‐2s‐1, respectively, over the 20‐h period. Screw‐capped reaction vials sealed with white silicone rubber septa lost ethylene at the rate of 30.2 nl m‐2s‐1. The (NH4)2SO4 solution was utilized as a seal by inverting a vial so that the salt solution covered the internal surface of the vial septum. Saturated (NH4)2SO4 solution is an effective seal. Silicone rubber should be avoided as a seal in systems for containing ethylene. Ethylene production values in the literature may be underestimates where silicone rubber seals have been used.
Évolution horaire au cours d'une journée normale de la photosynthèse, de la transpiration, de la respiration foliaire et racinaire et de la nutrition N.P.K. chez Zea mays
Authors: MASSIMINO DANIEL , ANDRÉ MARCEL , RICHAUD CHRISTIANE , DAGUENET ALAIN , MASSIMINO JACQUELINE , VIVOLI JEAN
Published: April 2006

Hourly development during a normal day of photosynthesis, transpiration, leaf and root respiration, and of N.P.K nutrition in Zea mays.

Metabolism of Zea mays L. cv. INRA F7×F2 can be measured hourly with the “C23A system”, under favourable and constant growth conditions. The photosynthesis is especially stable and is submitted only to a development linked with the leaf surface growth. During the vegetative stage the leaf surface increases regularly both in the day and in the night. The water loss does not change during the diurnal period and remains important during the night if humidity is less than 100%. The leaf respiration is nearly stable. The root respiration, measured with O2 and CO2, fluctuates according to a typical rhythm with two maxima. Day and night mean rates were about the same. The respiratory quotient is about one during the vegetative stage. There is no decrease in the rate of phosphate absorption during the night, and a very small decrease in the rate of nitrate absorption. Ammonium is totally consumed in the first hours after renewal of the nutrient solution. At the same time the potassium consumption is decreased, and then presents a maximum followed by a night reduction. Under our conditions, all of the observations allowed us to assume the presence of an adequate reserve of assimilates and suggest the existence of a precise regulation process, which can ensure an even day night functioning of the plant metabolism, but which does not preclude the presence of internal rhythms, as indicated by the oscillation of the root respiration.
Low temperature, gibberellin and acid lipase activity in removal of apple seed dormancy
Authors: ŻARSKA‐MACIEJEWSKA BOŻENA , SIŃSKA IRENA , WITKOWSKA EWA , LEWAK STANISŁAW
Published: April 2006

The activity of acid lipase and the level of gibberellin A4 (GA4) were determined in apple embryos excised from seeds after different time periods of stratification and subsequently cultured in darkness at 4°C or at 25°C. Enzyme activity and GA4 content were higher at 4°C. Exogenous gibberellin stimulated lipase activity, while AMO‐1618, an inhibitor of gibberellin biosynthesis, inhibited, to the same degree, both the enzyme activity and the GA4 accumulation. The involvement of GA4 and lipolytic enzymes in cold‐mediated removal of embryonal dormancy has been discussed and compared with the role of these two factors in light‐stimulated germination of dormant apple embryos, described earlier (Smoleńska and Lewak 1974).
Turnover of cell wall polysaccharides of a Vinca rosea suspension culture
Authors: TAKEUCHI YUICHI , KOMAMINE ATSUSHI , SAITO TOMOO , WATANABE KAZUO , MORIKAWA NAOTAKE
Published: April 2006

Three‐day‐cultured cells of Vinca rosea L. (in the cell division phase) and 5‐day‐cultured cells (in the cell expansion phase) prelabelled with d‐[U‐14C] glucose were incubated in a medium containing unlabelled glucose. After various periods of chase, extra‐cellular polysaccharides (ECP) and cell walls were isolated, and cell walls were fractionated into pectic substances, hemicellulose, and cellulose fractions. After acid hydrolysis, the radioactive constituents in the pectic substances and hemicellulose fractions were analyzed. Active turnover was observed in arabinose and galactose in the hemicellulose fraction of cell walls, while the constituents of the pectic substances, and xylose and glucose in the hemicellulose fraction did not undergo active turnover. The proportion of radioactivities of arabinose and galactose in total radioactivity of ECP increased markedly after chasing. These results indicate that arabinogalactan was synthesized, deposited in the cell wall, degraded rapidly, and made soluble in the medium as a part of ECP.
Occurrence of steryl and wax esters in Dicranum elongatum
Authors: KARUNEN PIRJO , MIKOLA HEIKKI , EKMAN RAINER
Published: April 2006

The steryl and wax esters of the frozen subarctic moss Dicranum elongatum Schleich contained fatty acids 39.8 mg per gram dry green tissue. The content decreased with increasing age of the moss shoots, but no great changes were found in the fatty acid pattern of the esters. The major part of the steryl and wax ester fraction of the green shoots was made up of esterified sterols (85%), and the rest (15%) of esterified aliphatic alcohols. No great changes were found in their relative proportions with increased age of the shoots. Some changes were evident in the pattern of individual esterified sterols, however. The proportion of cycloartenol was lower in the older parts than in the green part, and the proportion of campesterol, stigmasterol, and β‐sitosterol were lower in the green part. The major esterified aliphatic alcohols were 1‐octadecanol, phytol and geranylgeraniol. The proportion of geranylgeraniol was highest in the green part and that of phytol in the older parts. The main alcohol of the surface lipids was 1‐octadecanol.
Induction of DNA synthesis by 2,4‐dichlorophenoxyacetic acid during callus induction in Jerusalem artichoke tuber tissues
Authors: YAJIMA YASUO , YASUDA TAKESHI , YAMADA YASUYUKI
Published: April 2006

During the induction of DNA synthesis in Jerusalem artichoke (Helianthus tuberosus L.) tuber by 2,4‐D, the 2‐14C‐2, 4‐D from the agar medium rapidly incorporated into the ethanol soluble and insoluble fractions. Although the 2,4‐D level in the ethanol soluble fraction decreased on transplantation of the tissue from the 2‐14C‐2,4‐D medium to medium without the auxin, its level in the buffer‐soluble and ‐insoluble macromolecular fractions increased. The purified, buffer‐insoluble macromolecules were chromatin. The 2,4‐D binding to chromatin particularly increased during DNA synthesis. The histone contents of chromatin decreased as DNA synthesis progressed. The polyacrylamide gel electrophoretic patterns of the histones showed a decrease in the moderately lysine‐rich histone fraction as compared to other fractions. Thus, the decrease in the histone level caused by 2,4‐D and the presence of the 2,4‐D moderately lysine‐rich histone complex may be closely related to the induction of DNA synthesis by 2,4‐D in cells.
The effects of irradiance on growth, respiration and nitrate reductase activity of Terminalia ivorensis and Terminalia superba
Authors: FASEHUN F. E.
Published: April 2006

Controlled‐environment experiments were conducted to determine the effect of three irradiance levels obtained by artificial shading (40%, 65% and 100% light) on the growth, distribution of photosynthate, relative growth rate, net assimilation rate, respiration and nitrate reductase activities in the leaves of seedlings of Terminalia ivorensis and Terminalis superba, two important tropical tree species.

Total dry weights of both species increased with increasing irradiance level during growth. Shading affected the percentage dry matter in the roots and number of leaves of both species. Relative growth rate, net assimilation rate, respiration and nitrate reductase in the leaves of both species increased with increases in irradiance level during growth. Significant differences between the species were observed in most of the parameters studied.
Polyamines, storage substances and abscisic acid‐like inhibitors during dormancy and very early activation of Helianthus tuberosus tuber tissues
Authors: BAGNI NELLO , MALUCELLI BARBARA , TORRIGIANI PATRIZIA
Published: April 2006

Abstract Dormancy and break of dormancy of tubers of Helianthus tuberosus L. (Jerusalem artichoke) have been investigated in regard to the possibility that polyamines can control these processes. Polyamines were detected by the method of direct dansylation and abscisic acid was bioassayed using wheat coleoptile growth test. Arginine and glutamine, which are the main store nitrogenous organic compounds of Helianthus tuberosus tuber, decrease during the last phase of dormancy as well as abscisic acid; moreover the corresponding increase in polyamines (putrescine, spermidine and spermine) seems to be strictly related to the break of dormancy of tuber. The artificial break of dormancy induced by 2,4‐dichlorophenoxyacetic acid stimulates a great increase in polyamines, just evident within 15 min after activation, and a corresponding decrease in arginine and glutamine. The levels of polyamines, at 1 h of activation are sufficient to stimulate protein synthesis in vitro.
Effect of SO32‐ on the activity of ribulose bisphosphate carboxylase from seedlings of Pinus silvestris
Authors: GEZEILUS KERSTIN , HALLGREN JAN‐ERIK
Published: April 2006

Abstract The effect of sulphite on ribulose bisphosphate carboxylase, extracted from needles of Pinus silvestris L., was studied in vitro at pH 8.15 and 25°C. 1 mM and higher concentrations of SO32‐ inhibited the enzyme.

The enzyme was activated either in the assay medium (2.5 – 20 mM HCO3, 20 mM MgCl2) or in 10 or 20 mM HCO3‐ and 20–25 mM MgCl2. Linear reciprocal plots of the activity versus the substrate concentration were obtained, when the HCO3‐ concentration during activation was 4 mM or higher. When the enzyme was activated at high HCO3‐ and Mg2+ concentrations, the Km(CO2) was c. 27 μM. With respect to HCO3‐. SO32‐ inhibited the enzyme in a non‐competitive fashion. The inhibition was similar, whether SO32‐ was present during activation or not. Apparently. SO32‐ did not interfere with the binding of CO2 and Mg2+ at the activating site. The K1 was 11–13 mM SO32‐. With respect to ribulose bisphosphate the inhibition was also noncompetitive.

Similar results with respect to HCO3‐ were obtained for spinach, Spinacia oleracea L., which is contrary to earlier reports.
Antibody inhibition of external aldolase activity in spinach chloroplast preparations
Authors: LARSSON CHRISTER , LIDERT ZEV , BERZBORN RICHARD J.
Published: April 2006

Abstract Antibodies (rabbit) have been prepared against total stroma from isolated spinach (Spinacia oleracea L. cv. Viking II) chloroplasts. These antibodies inhibited most of the aldolase activity present outside the chloroplasts in preparations of intact (80–95%) chloroplasts. They also reduced the amount of labelled fructose‐1,6‐bisphosphate found in the medium after 14CO2 fixation with such preparations. Both intact and broken chloroplasts were strongly agglutinated by the antibodies. The results indicate that the external fructose‐1,6‐bisphosphate was formed from excreted dihydroxyacetone phosphate by the action of aldolase and triose phosphate isomerase present outside the chloroplasts. The contamination of organelle preparations with free enzymes or enzymes adsorbed on the outer surface of the organelles is probably a general phenomenon. It is suggested that antibodies can be used as a tool to detect and selectively inhibit such contaminating enzyme activities.
Stimulation of nitrogenase activity and photosynthesis in some cyanobacteria by glyoxylate
Authors: BERGMAN B.
Published: April 2006

Abstract The effect og glyoxylate on nitrogenase activity (C2H2 reduction) and photosynthesis (H14CO3 fixation and O2 evolution) was in vestigated in the three heterocystous cyanobacteria Anabaena cylindrica, A. variabiltis and N. muscorum. Glyoxylate had virtually no effect on the rate of dark respiration and was unable to sustain photoheterotrophic growth, though some slight stimulation (= 30%) of photorophic growth was noted. A considerable stimulation of both nitrogenase and photosynthetic activities was observed in presence of glyoxylate. In the light the stimulation increased with time up to about 15‐25 h after adding optimal concentrations of 4–6 mM glyoxylate. Placing glyoxylate treated samples in the dark or adding DCMU (30 μM) in the light, showed that glyoxylate initially supported significantly higher nitrogenase activity than did samples in absence of glyoxylate. However, after a prolonged incubation in the dark or in presence of DCMU glyoxylate is unable to relieve the adverse effects of such conditions. The stimulation of the nitrogenase activity was even more pronounced when the glyoxylate was added to cells preincubated in the dark (“carbon starved”) than for cells kept constantly in light. The results suggest that glyoxylate, or a metabolite, may act as an inhibitor of cyanobacterial photorespiration and this hypothesis is discussed.
Cell wall glycoproteins from Chlamydomonas reinhardii are sulphated
Authors: ROBERTS K. , GAY M. R. , HILLS G. J.
Published: April 2006

Abstract Both the two major structural cell wall glycoproteins and the soluble excreted glycoproteins of Chlamydomonas reinhardii Levine WT II/32 contain low levels (approx. 1–4%) of sugar O‐sulphate esters, asymmetrically distributed within the molecules. Preliminary characterization of their structure is described through [35S] sulphate labelling experiments. The function of the sulphated glycoproteins is discussed in terms of their structural role and their water retaining properties.
Chlorophyll b accumulation and grana formation in low intensities of red light
Authors: RYBERG HANS , AXELSSON LENNART , WIDELL KARL‐OLOF , VIRGIN HEMMING I.
Published: April 2006

Abstract When dark grown leaves of wheat (Triticum aesivum L.) were given a brief irradiation, there was an immediate onset of chlorophyll (Chl) b synthesis in the dark. This synthesis led to a rather slow accumulation of Chl b, which ceased when the Chl b/Chl a ratio had reached a value of about 0.1. The Chl b synthesis occurred also when the seedlings were treated with the herbicide SAN 9789. Leaves grown under different intensities of red light accumulated Chl b and Chl a, resulting in a ratio Chl b/Chl a which depended on the light intensity. If the light intensity was low, Chl a accumulated to a level about ten times the level of PChlide of the dark grown leaves. This occurred without any increase in the Chl b/Chl a ratio. There was no difference between SAN 9789‐treated seedlings and water controls in this respect. Above a certain threshold of irradiance, the Chl b/Chl a ratio in the control leaves increased rapidly with the irradiation intensity. The increase in Chl b/Chl a ratio coincided with formation of grana in the plastids. This increase was not found and grana formation was completely absent in the seedlings treated with SAN 9789. The possibility of two different stages in the Chl b synthesis is discussed.
Chlorophyll formation and the development of photosynthesis in dark grown seedlings of Picea abies
Authors: BARTLETT D. W. , DODGE A. D.
Published: April 2006

Abstract Seeds of Picea abies were germinated and grown in either darkness or constant light. The chlorophyll content and photosynthetic carbon dioxide uptake of developing seedlings of different ages was determined. Ten‐day‐old dark grown seedlings showed an instant ability for photosynthetic carbon dioxide uptake and also formed further chlorophyll most rapidly upon subsequent illumination. These activities progressively diminished when the dark growth period was extended. Light grown seedlings reached a maximum chlorophyll level after 15 days growth, and this preceded maximal photosynthetic development.
Effect of potassium on growth and nitrate reductase during water stress and recovery in maize
Authors: KHANNA‐CHOPRA R. , CHATURVERDI G. S. , AGGARWAL P. K. , SINHA S. K.
Published: April 2006

Abstract The effect of potassium (0,50, 100 and 200 mg/pot) was studied on growth characteristics and nitrate reductase activity in maize (Zea mays) seedlings during water stress and subsequent recovery. In irrigated plants K+ increased the rate of leaf area expansion, leading to increased leaf area per plant. Increased leaf area was associated with decreased chlorophyll content. Water stress (–15 bars) enhanced the stomatal resistance of leaves which was further accentuated by K+ application. Nitrate reductase activity rose in irrigated plants 24 h after K+ application. Subsequently, as water stress developed, K+ helped to maintain higher NR activity for the first two days. However, K+ had no effect on half life of NR in light or darkness. During recovery from stress K+ aided to maintain the higher leaf expansion rate, the chlorophyll content and the stomatal resistance. The results above are discussed in relation to the ability of K+ to maintain better growth under water stress.
Effects of phenolic substances on metabolism of exogenous indole‐3‐acetic acid in maize stems
Authors: LEE T. T.
Published: April 2006

Four‐day‐old stem segments of Zea mays L. cv. Seneca 60 were treated sequentially with phenolic substances and indole‐3‐acetic [2‐14C] acid ([2‐14C]IAA). Formation of bound IAA was rapid, but a pretreatment with p‐coumaric acid, ferulic acid or 4‐methylumbelliferone decreased the level of bound IAA. The decrease is not likely related to the effect of the phenolics on enzymic oxidation of IAA, since the level of free IAA was not limiting and the activity of ferulic acid in enzymic oxidation of IAA is different from that of p‐coumaric acid and 4‐methylum‐belliferone. Apparently these compounds inhibited the formation of bound IAA and consequently caused an accumulation of free IAA. In contrast, caffeic acid, protocatechuic acid and 2,3‐dihydro‐2, 2‐dimethyl‐7‐benzofuranol had little effect.

After the uptake of IAA there was a slow but steady incorporation of the radioactivity into the 80% ethanol‐insoluble, 1 M NaOH‐soluble fraction. Phenolic substances also affected this process. The compounds which are cofactors of IAA‐oxidase increased the incorporation while those which are inhibitors of IAA‐oxidase decreased the incorporation. Results suggest that the phenolics also affected the enzymic oxidation of IAA in vivo in the same way as in vitro.
Turnover of cell wall polysaccharides of a Vinca rosea suspension culture
Authors: TAKEUCHI YUICHI , KOMAMINE ATSUSHI
Published: April 2006

Five‐day‐cultured cells of Vinca rosea suspension culture were labelled with D‐[U‐14C]glucose for 3 h and were then incubated in a medium containing unlabelled glucose for 24 h. Before and after chasing, extra‐cellular polysaccharides (ECP) and the cell walls were isolated from the medium and cells, respectively. ECP and polysaccharides in the hemicellulose fraction of cell walls were fractionated into a fraction precipitated as copper salt and one not precipitated as copper salt, and the latter was further fractionated using cellulose‐powder chromatography. From the results of analyses of the sugar composition and methylation analyses, components of polysaccharides contained in each fraction were deduced. In ECP, the percentage of radioactivity in the arabinogalactan fraction increased during chasing, while in the cell wall radioactivity in the fraction containing arabinogalactan decreased during chasing. These results confirm the view that arabinogalactan in the cell wall is degraded, and secreted into the medium as a part of ECP.
Plantlet formation from embryonic tissue of chestnut grown in vitro
Authors: VIEITEZ ANA M. , VIEITEZ E.
Published: April 2006

Development of axillary shoots was induced when isolated embryonic axes of chestnut (Castanea sativa Mill.) were cultured on a defined medium containing 6‐benzyl‐aminopurine (BAP). The optimal concentrations of BAP were determined for development of axillary shoots from both embryonic axes and subcultured shoots. After shoot multiplication a great number of shoots have been maintained sequentially without significant change in the proliferative rate for one year. Limited rooting has been obtained with excised shoots. Indole‐3‐butyric acid (IBA) at 2 mg/l was used to induce root primordia. After 8 days of treatment the plantlets were transferred to an auxin‐free medium for root development.
Importance of the caryopsis in root growth and georeaction
Authors: NEY DANIEL , PILET PAUL‐EMILE
Published: April 2006

Geocurvature of horizontally placed apical segments of maize (cv. INRA 258), the lateral curvature of half‐decapitated segments in vertical position, and the curvatures of intact primary roots (horizontal or vertical) still attached to their caryopses were analysed in white light. The results may be explained in terms of the growth properties of certain endogenous regulators. The caryopsis could be the source of some precursors of growth inhibiting substances produced or released in the cap cells and also of growth activators. The relative effects of these factors – acting in the elongating zone of growing roots – clearly depend on the orientation of the caryopsis.
Effects of ionic strength and relative humidity on the efflux of K+ (86Rb) and Ca2+ (45Ca) from roots of intact seedlings of cucumber, oat and wheat
Authors: JENSÉN PAUL , KYLIN ANDERS
Published: April 2006

Spring wheat (Triticum aestivum L. cv. Svenno), oat (Avena sativa L. cv. Brighton) and glasshouse cucumber (Cucumis sativus L. cv. Bestseller F1) were cultured for a week after germination on complete nutrient solutions of three different dilutions (1, 25 and 50% of the full strength medium). K+(86Rb) and 45Ca were present during the whole culture period. Relative humidity (RH) was 50% except during the last day, when half the material was transferred to 90% RH. Efflux of labelled ions was then followed during eight hours on unlabelled solutions of the same composition as before, and at both 50% and 90% RH in the atmosphere. – Uptake of K+(86Rb) during growth tended to be saturated in the 25% medium. Contrariwise, the level of Ca2+ in the roots increased continuously with strength of the medium. At low concentrations cucumber roots were higher in Ca2+ than roots of oat or wheat, whereas all three species showed similar levels of Ca2+ in 50% medium. – At the lowest ionic strength, smooth efflux curves were obtained that could be resolved according to the three‐compartment theory. At higher ionic strength, irregularities were observed, and more for Ca2+ than for K+; but for practical purposes compartment analysis with the same time constants could be applied as for the lowest concentration. – Discrimination between K+ and Rb+ differed between the roots, but not much between the shoots of different species. The roots of oat and wheat took up Rb+ preferentially over K+ in the 25% and 50% media; whereas K+ was preferred over Rb+ or little discrimination made in 1% medium and for cucumber. The shoots generally showed less discrimination than the roots. The main variability in discrimination between K+ and Rb+ thus appears to be localized in the tonoplasts of the roots cells. – Low RH around the shoots increased efflux of K+(86Rb) from the cytoplasm and vacuoles of the root cells as compared to the efflux at high RH. DNP (2,4‐dinitrophenol) in the medium had the same effect as high RH around the shoots. The signal system that must exist between shoots and roots is discussed as a response to “drought” conditions. In relation to investigations of others, it is assumed that the effect of DNP may indicate that part of the chain between roots and shoots consists of metabolically influenced sites, whose output is influenced by the rate of water transport.
Comparative study of RNA metabolism in freshly isolated protoplasts and callus cultures of Parthenocissus tricuspidata crown gall
Authors: ZUILY‐FODIL Y. , ESNAULT R.
Published: April 2006

RNA metabolism was compared in protoplasts and cells of Parthenocissus tricuspidata crown gall callus. A rapid increase in the permeability to precursors during the first three hours following the termination of protoplast isolation was observed. Consequently, RNA synthesis occurred at a higher rate in protoplasts than in whole cells. On the other hand, protoplasts and callus tissues showed similar kinetics of incorporation of precursors into mature rRNA's. Pulse‐chase experiments showed the maturation rate to be nearly the same in both cases.
Succinate oxidation by coupled potato tuber mitochondria followed by rapid scan spectrometry
Authors: DUCET GASTON
Published: April 2006

Oxidation of succinate by potato tuber mitochondria has been investigated from aerobiosis to complete anuerobiosis. Difference spectra of the various steps were recorded by a rapid scan spectrometer delivering averaged spectra every 3 s in the range 380 to 630 mm.

The transitions between state 3 and 4 resulted in large redox changes, essentially for the b cytochromes, and in significant changes in the spectral baseline (light scattering). At anaerobiosis the cytochromes c, c1 and a were reduced while cytochrome a, remained oxidized. – Addition of uncouplers in aerobiosis induced oxidation of the b cytochromes, and when anaerobiosis occurred cytochromes c, c1a and a3 were reduced simultaneously. When uncouplers were added in anaerobiosis a partial oxidation of the b cytochromes and the reduction of cytochrome a3 were observed.

These results are interpreted as the building up of a membrane potential, maximal in state 4 and stable after anaerobiosis. The cytochromes buried in the membrane equilibrate with the membrane potential, and their redox states are sensitive to the changes. Variations of membrane potential also induce changes in the light scattering by the mitochondrial membrane.
The influence of zinc and light conditions on the cadmium‐repressed growth of the green alga Coelastrum proboscideum
Authors: MÜLLER KLAUS W. , PAYER HANS‐D.
Published: April 2006

The growth response of Coelastrum proboscideum Bohlin to cadmiun (3 × 10−9M to 2.4 × 10−7M) was studied. The inorganic media used varied in zinc concentration (1.3 × 10−7M to 3.6 × 10−6M). The data were evaluated by factorial analyses. The influence of zine on the growth depression by cadmium depended on the light conditions (16:8 h light:dark cycles or 24 h continuous illumination periods). Intermittent illumination caused a negative interaction of zinc and cadmium in contrast to a positive interaction or additive effects of these elements during continuous illumination.
Growth and curvature in seedlings of Pisum sativum and an ageotropic mutant
Authors: OLSEN GUNN MARI , IVERSEN TOR‐HENNING
Published: April 2006

In an attempt to explain the influence of gravity on the behaviour of ageotropic plant organs, a pea mutant (Pisum sativum ageotropum) and normal pea (Pisum sativum cv. Sabel) were examined. The mutant has a significantly lower germination rate (large seeds: 25%, small seeds: 10%) than normal pea seeds (55%). Removal of testa increased germination dramatically, the values obtained were 63 and 89%, respectively. Immediately after imbibition the mutant from which the testa had been removed, developed more slowly than normal pea seeds; after 28 h the difference in elongation rate between the two types was reversed. When continuously stimulated geotropically in the horizontal position the elongation in the mutant is larger than in the normal pea roots kept in the same position. During a 24 h period starting 48 h after imbibition the mutant root elongated 45.0 mm while the value for the normal pea root was 11.5 mm.

The course of the geotropic curvature in roots of the two types has been followed during a period of 24 h. Normal pea roots develop an asymmetry in the extreme root tip region after 30 min of horizontal stimulation. After prolonged stimulation (exceeding 2 h) the asymmetry has disappeared and the curvature distributed over the entire growth region. When roots of normal pea are stimulated continuously at various angles, the optimum angle of geotropic response is 90° with decreasing responses in the order 135° (i.e. the root tip is pointing obliquely upward) and 45°. The presumed ageotropic behaviour of the mutant has only to a certain extent been confirmed in the present study. When stimulated at 135° a slight positive curvature developed; stimulation at 90° and 45° gave a slight negative curvature.
Qualitative and quantitative changes in nitrogenous compounds in senescing leaf and bark tissues of the apple
Authors: KANG SEONG‐MO , TITUS JOHN S.
Published: April 2006

Quantitative and qualitative changes in proteins and ethanol‐soluble nitrogen were followed in senescing leaf and bark tissues of ‘Golden Delicious’ apple trees (Malus domestica Borkh.). While senescing leaves lost 46% of their proteins, total bark protein increased 240% during senescence. However, the protein nitrogen gain in bark tissue was about the same as the protein nitrogen loss in leaf tissue per unit fresh weight of tissues. The pattern of bark protein accumulation appears to be gradual from early August to November and sequential from lower to higher molecular weight species of proteins. The final electrophoretic profile of total bark proteins was established at the later stages of senescence. By late November, 89% of the nitrogen in the bark tissue was found in proteins with 11% in the ethanol‐soluble fractions. The total protein content of dormant bark tissue was 3.5% per gram dry tissue. Fractionation of the total bark proteins by DEAE‐cellulose chromatography indicated that the final upsurge of bark proteins observed in November was associated primarily with one group of proteins (Peak III).
Activity profiles of enzymes involved in glutamine and glutamate metabolism in the apple during autumnal senescence
Authors: KANG SEONG‐MO , TITUS JOHN S.
Published: April 2006

Seasonal changes in glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 2.6.1.53), and glutamate dehydrogenase (EC 1.4.1.3) were measured in both senescing leaf and bark tissues of ‘Golden Delicious’ apple trees (Malus domestica Borkh.). From the measured enzyme activities we attempted to estimate the in vivo catalytic potentials of the enzymes with special reference to nitrogen mobilization and conservation of senescing apple trees. The cumulative glutamine synthetase activity of leaf tissue was about three times higher than that of bark. The estimated catalytic potential of leaf glutamine synthetase was 800‐fold higher than the actual protein nitrogen loss of senescing leaves. The cumulative glutamate synthase activity of bark was about six times higher than that of leaf. The estimated catalytic potential of bark glutamate synthase was 160‐times higher than the actual protein nitrogen gain in that tissue. The cumulative glutamate dehydrogenase activities in leaf and bark tissue were approximately the same. However, the catalytic potential of leaf glutamate dehydrogenase was twice that of leaf glutamate synthase. It is thus concluded that the physiological role of glutamine synthetase in senescing leaf tissue is to furnish the amide(s) prior to mobilization of nitrogen to storage tissue. The higher activity of glutamate synthase in bark tissue could provide a mechanism to transform the imported amide nitrogen to amino nitrogen of glutamate for storage protein synthesis. The possible regulatory factors upon the activity of these enzymes in the tissues of senescing apple trees are discussed.
Nitrogen assimilation by a Citrus tree
Authors: KATO TADASHI
Published: April 2006

Primary assimilation of 15N‐ammonium or 15N‐nitrate by excised leaves of satsuma mandarin (Citrus unshiu Markovitch) was examined under light and dark conditions. Under both conditions both types of nitrogen were most markedly incorporated into glutamine‐amide nitrogen in the primary step of the assimilation, and into proline in the later steps. Incorporation of ammonium or nitrate into amino acids was more active in the light than in the dark, although the stimulating effect of light on the incorporation was relatively small in both cases.
Effect of ortho‐dihydroxyphenols on growth and protein pattern of callus cultures from Prunus avium
Authors: FEUCHT W. , SCHMID P. P. S.
Published: April 2006

Excised shoot discs from Prunus avium L. were cultivated on a modified Murashige and Skoog medium for 4 weeks under long day conditions. The basal medium was supplemented with IAA and benzylaminopurine. Further addition of 5.7 × 10−5 resp, 11.4 × 10−5M catechin and 4.25 × 10−5 resp. 8.5 × 10−5M chlorogenic acid resulted in a highly significant promotion of callus proliferation. Proteins and enzymes were separated by isoelectric focusing. The supply of both polyphenols resulted in a higher number and intensity of protein bands including esterases as compared to controls.
Growth control by phytochrome of de‐etiolated bean hypocotyls mediated by chlorophyll fluorescence
Authors: ROTH‐BEJERANO N.
Published: April 2006

The elongation of hypocotyls excised from de‐etiolated seedlings of beans (Phaseolus vulgaris L. cv. British Wax) is inhibited by light, blue and red irradiations being equally effective. Conditions which decrease chlorophyll fluorescence, such as CO2‐free air, abolish the inhibitory effect of blue irradiation and enhance the inhibition by red light. Conversely, conditions which increase chlorophyll fluorescence, such as a N2 atmosphere or irradiation through a chlorophyll filter, abolish the inhibitory effect of red light and enhance the inhibition by blue irradiation. The inhibitory effect of blue light is reversible by red irradiation under increased fluorescence as well as by far red. We propose that the chlorophyll fluorescence excited by blue and red irradiations in λF > 660 nm and λF > 720 nm, respectively, is responsible for the inhibitory effect of blue light and the reduction of the inhibitory effect of non fluorescing red light. Both red and blue wavelengths seem, therefore, to control hypocotyl elongation through phytochrome.
Membrane lipids in heat injury of spinach chloroplasts
Authors: SANTARIUS KURT A.
Published: April 2006

Heat treatment of intact leaves and of isolated thylakoid membranes from spinach (Spinacia oleracea L. cvs. Monatol and Montako) caused inactivation of photochemical processes such as electron transport through photosystem II and photophos‐phorylation. Membrane lipid analysis demonstrated that heat‐induced damage to thylakoids is not caused by chemical alterations in the lipids such as oxidation of unsaturated fatty acids, or release of free fatty acids due to hydrolysis of lipids. Partial extraction of lipids from isolated chloroplast membranes before and after thermal inactivation do not point to drastic changes in the binding relations of the lipids within the membranes. However, it cannot be excluded that during high temperature treatment changes in lipid‐lipid interactions and/or delocalization of specific lipids within the thylakoids might be responsible for the disorganization of the functional integrity of the membranes. Since thermostability of chloroplast membranes is decreased when they are exposed to free unsaturated fatty acids, small amounts of membrane lipids which become hydrolyzed during extended heat treatment may partly contribute to primary heat damage.
Hormonal factors controlling the initiation and development of lateral roots
Authors: WIGHTMAN FRANK , THIMANN KENNETH V.
Published: April 2006

As the first part of a comprehensive study of the hormonal control of lateral root initiation and development, the effect of surgical treatments such as removal of the root tip, one or more cotyledons, the young epicotyl, or combination of these treatments, on the induction and emergence of lateral roots on the primary root of pea seedlings has been examined. Results show that removal of the root tip leads to a rapid but transitory increase in the number of lateral primordia, the largest number arising in the most apical segment of decapitated roots suggesting the accumulation of acropetally moving promoter substances in this region. The cotyledons appear to be the main source of promoter substances for both the induction and emergence of lateral roots, although one or more promoters also appear to be produced in the epicotyl. The data further indicate that the root tip is possibly the source of a substance which moves basipetally and interacts with acropetally moving promoters to regulate the zone for lateral primordia initiation; the root tip also appears to be the source of a powerful inhibitor of lateral root emergence.
Embryonic control of isocitrate lyase activity in the megagametophyte of ponderosa pine seeds
Authors: MURRAY EDWARD W. , ADAMS ROBERT E.
Published: April 2006

A previous report (Bilderback 1974) presented evidence for embryo enhancement of isocitrate lyase (threo‐L, isocitrate glyoxylate lyase, EC 4.1.3.1) activity in the megagametophytes of stratified germinating Pinus ponderosa Laws. var. ponderosa seeds. Our data indicate that the rate of increase in specific activity of this enzyme was greater during the first four days under germination conditions in ponderosa pine megagametophytes from which embryos had been excised than in megagametophytes with embryos left in situ for a 12‐day incubation period. Enzyme activity also increased more rapidly in megagametophytes with embryos removed after 2 days incubation than in those that retained their embryos for the full incubation period. Although rate of increase in enzyme activity was greater in embryoless megagametophytes than in those retaining their embryos, highest levels of activity ultimately occurred in the latter. Thus embryo presence was associated with inhibition of the rate of development of enzyme activity but it was also responsible for a pattern of sustained enzyme activity. These phenomena were not dependent on stratification. Possible reasons for differences between certain aspects of our study and the above cited report are discussed.
Tentoxin effects on infrastructure and greening of ivyleaf morningglory (Ipomoea hederacea var. hederacea) cotyledons
Authors: DUKE STEPHEN O. , PAUL REX N. , WICKLIFF JAMES L.
Published: April 2006

The effects of 20 μM tentoxin on mesophyll chloroplast ultra‐structural development, chlorophyll organization and accumulation, and pigment transformations in cotyledons of dark‐grown, 4‐day‐old ivyleaf morningglory [Ipomoea hederacea (L.) Jacq. var. hederacea]were monitored. After 6 h of white light (200 μEm−2T.s−1), many plastids of tentoxin‐treated tissues contained prolamellar bodies or inconsistent internal membrane orientation in contrast to the uniform internal membrane orientation and absence of prolamellar bodies in controls. Grana stacking did not progress beyond three to four disc loculi in tentoxin‐treatments, and fret membranes were usually discontinuous and reduced. Cylindrical or cupped grana appeared in many chloroplasts after 3 days of light, while other chloroplasts in which disruption was more pronounced had few grana except for remnants, but usually did possess vesicles or structures resembling prolamellar bodies. Tentoxin had no apparent effect on stroma density or plastoglobuli size and number. No starch grains appeared in any of the tentoxin treatments, whereas they appeared after 24 h in controls. Initial protochlorophyllide content and its photoconversion to chlorophyllide and subsequent Shibata shift were not affected by tentoxin. Chlorophyll accumulation rates in tentoxin‐treated cotyledons were about 10% of control rates during the first 24 h of greening and about 20% of controls from 48 to 72 h of greening. Chlorophyll alb ratio and PSU size (total Chl/P700) were not significantly affected by tentoxin.
Recovery of loss in chlorophyll and 2,6‐dichlorophenol indophenol Hill reaction of isolated chloroplasts during dark induced aging of intact maize seedlings
Authors: CHOUDHURY N. K. , BISWAL U. C.
Published: April 2006

Loss in the content of pigments and decline in the efficiency of thylakoid membranes to reduce 2,6‐dichlorophenol indophenol (DCPIP) have been investigated during dark induced senescence of attached leaves of maize seedlings. The chlorophyll degradation during senescence is differentially inhibited by indoleacetic acid (IAA), gibberellic acid (GA) and kinetin. IAA and GA behave as mild senescence inhibitors in comparison to kinetin. However, in comparison to light, kinetin is relatively less efficient in counteracting senescence. Dark‐induced loss in chlorophyll content is fully recovered by light when the dark incubation period is relatively short. The pattern of light recovery of loss in photoelectron transport during dark‐aging is similar to the recovery kinetics of chlorophyll. Continuous kinetin treatment of dark‐incubated seedlings inhibits the chlorophyll degradation but with decreased duration of kinetin treatment, the efficiency of the hormone to inhibit chlorophyll loss is reduced. The kinetin‐induced inhibition of pigment loss is small in comparison with the effect of light.
Cyclic adenosine‐3′: 5′‐mono phosphate: Production and extracellular release from green and blue‐green algae
Authors: FRANCKO DAVID A. , WETZEL ROBERT G.
Published: April 2006

Cellular and extracellular levels of cAMP were analyzed in the blue‐green algae Microcystis aeruginosa, Anabaena flos‐aquae, and Synechococcus leopoliensis and the green algae Chlorella pyrenoidosa, Cosmarium botrytis, Pandorina morum, Scenedes‐mus communis, and Pediastrum biradiatum. On the basis of chromatographic analyses, and several biochemical assays, each alga produced cAMP and released it into the medium. Cellular cAMP (92–394 pmol g−1) and extracellular cAMP (8–440 pmol liter−1) varied greatly among species.
The effect of temperature on the germination‐promoting activities of cytokinin and gibberellin applied to celery seeds (Apium graveolens)
Authors: BIDDINGTON NORMAN L. , THOMAS TUDOR H. , DEARMAN ANTHONY S.
Published: April 2006

Celery seeds (Apium graveolens L. cv. Lathom Blanching) made dormant by high temperature pretreatment (28–40°C) during imbibition in the dark, germinated at 22°C in the light after treatment with benzyladenine (BA). This BA‐induced promotion of germination increased with increasing pre‐treatment temperature from 32 to 38°C. whether BA was given before or after pretreatment.

A mixture of gibberellins A4 and A7 (GA4/7) given before a 4 day high temperature pretreatment at 32°C partially inhibited the germination‐promoting activity of GA4/7 given after. It is suggested that gibberellin induces the formation of a thermola‐bile product which is necessary for germination, the precursor of which has a limited source.
Peanut and horse radish peroxidase isoenzymes. Intraspecies and interspecies immunological relatedness
Authors: CAIRNS EWA , HUYSTEE ROBERT B. VAN , CAIRNS WILLIAM L.
Published: April 2006

The presence of structural similarities in peroxidase isoenzymes was demonstrated by the technique of crossed immunoelec‐trophoresis. Isoenzymes found in the medium of peanut (Arachis hypogaea L.) cells grown in suspension culture were immuno‐precipitated in different arc systems according to the extent of relatedness of their antigenic determinants. Cross reactivity between isoenzymes in the medium was confirmed by demonstration that antibodies raised against only the glycoprotein fraction of the medium peroxidases would react also with the non‐glycosylated peroxidase isoenzymes that did not have affinity for Concanavalin A. Different peroxidase isoenzsmes from peanut leaves, peanut calli and peanut suspension cell medium share common antigenic determinants. Antibodies against peroxidase antigens from a different species, horse radish (Armoracia lapathifolia Gilib.), reacted with peroxidase antigens in the peanut cell medium. The results suggest a similarity of peanut peroxidases to horse radish peroxidase and. therefore, an evolutionary conservatism in peroxidase structure. The results also point to the potential utility of immunochemistry, including microcomplement fixation, to quantitate the structural similarities of peroxidase isoenzymes.
Changes in water potential and its components during shoot formation in tobacco callus
Authors: BROWN DANIEL C. W. , THORPE TREVOR A.
Published: April 2006

Shoot‐forming tobacco (Nicotiana tabacum L. cv. Wisconsin 38) callus maintains more negative water and osmotic potentials and more positive pressure potentials than non‐shoot‐forming callus. These differences are apparent by day 2 in culture, prior to any visible histological changes in the tissue, and are maximum by day 6, which is at the time of the first visible changes leading to organized development. The differences are maintained throughout the 28‐day culture period and are also evident in tissues grown under both low and high sucrose levels. Mannitol can partially replace sucrose in the maintenance of the above differences. It is suggested that the high water, osmotic and pressure potentials in the shoot‐forming tissue are maintained via (1) the accumulation of malate early in culture, (2) the presence of free sugars from the medium throughout the culture period, and (3) the degradation products of starch at the time of meristemoid formation and the succeeding organogentic phases.
In vitro phyllomorphic regeneration of shoot buds and shoots in Picea abies
Authors: JANSSON EVA , BORNMAN CHRIS H.
Published: April 2006

Needles (10–15 mm) of frost‐hardened 20–22‐week‐old (physiological age equivalent to 1 year) plants of Picea abies L. excised just after flushing, were induced to form adventitious shoot buds and shoots on media supplemented with BAP (6‐benzylaminopurine) and NAA (1‐napthaleneacetic acid). The addition of nanomolar concentrations (0.5–50) of NAA combined with 1–10 μM BAP considerably stimulated formation of pseudobulbils on the basal to mid‐part of the needle axis, as well as their subsequent development into shoot buds and shoots. On a medium containing 10 μM BAP, pseudobulbils that formed at the needle base did not develop further, but became necrotic and died with the omission of NAA. With 5 μM BAP + 50 nM NAA the initial phase of development was slow, but later showed good response and up to 22% of the needles produced shoot buds. Two to three shoots per needle could be excised and subcultured individually onto fresh media. It is concluded that the level of endogenous auxin decreases progressively from the needle's base to its tip, so that that concentration of exogenous auxin (50 nM NAA) which promotes pseudobulbil and shoot‐bud formation part‐way along the needle axis, simultaneously inhibits their induction at the needle base.
Barley leaf unrolling. The proline connection
Authors: Rajagopal R. , Madsen Axel
Published: April 2006

Unrolling of 1 cm sections, taken between 3 and 4 cm from the apex, of 6‐day‐old, etiolated barley leaves, was promoted by blue (426 nm) and red (658 nm) light. Accompanying such unrolling was a reduction in the level of the free proline of the tissue. When leaf unrolling was prevented by irradiation with far‐red (728 nm) light, or treatment with abscisic acid (ABA) following red light irradiation, the level of proline remained more or less unchanged, at the level of the untreated, dark controls. The proline analogue, azetidine carboxylic acid (AZC) powerfully inhibited the light induced leaf opening, emphasizing the significance of proline‐containing, structural and functional proteins in barley leaf unrolling. The inhibition imposed by AZC is partially reversible by added proline.