bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Growth Retardants on α‐Amylase Production in Germinating Barley Seed
Authors: Khan Anwar A. , Faust Maria A.
Published: April 2006

The effect of growth retarding compounds, (2‐chloroethyl)trimethylammonium chloride (CCC), 2‐isopropyl‐4‐dimethylamino‐5‐methylphenyl‐1‐piperidinecarboxylate methyl chloride (AMU‐1618), tributyl‐2,4‐dichlorobenzylphosphonium chloride (Phosfon D) and N‐dimethylamino succinamic acid (B‐995) on α‐amylase production in germinating barley seed was studied. Seeds were germinated in growth retardants in presence and absence of gibberellic acid (GA3). CCC, AMO‐1618 and Phosfon D inhibitedα‐amylase production in germinating seed and the effect was reversed by GA3 Phosfon D and AMO‐1618 were stronger inhibitors of α‐amylase production than CCC. CCC was by far the strongest inhibitor of all the other analogs tested. B‐995 was comparatively only slightly inhibitory.

The results reported here, when viewed in light of the results of other workers, provide good evidence that CCC, AMO‐1618 and Phosfon D inhibit α‐amylase production by inhibiting the synthesis of gibberellin or gibberellin‐like hormone(s) during germination of barley seed. Consistent with other reports, B‐995 possibly acts by other mechanism (s).
Influence of the Embryonic Axis on Protein Hydrolysis in Cotyledons of Cucurbita maxima
Authors: Wiley Lorraine , Ashton Floyd M.
Published: April 2006

Four‐day time course studies of the hydrolysis of cotyledonal storage protein were conducted on intact seeds, seed cotyledons detached from their embryonic axes and on detached cotyledon pairs germinated in the presence of three excised embryonic axes of Cucurbita maxima Duch., cv. Chicago Worted Hubbard. Detached cotyledons germinated alone showed little hydrolysis of the storage protein. However, the amount of protein hydrolysis of the detached cotyledon pairs germinated in the presence of three excised embryonic axes was comparable to the amount hydrolyzed in the cotyledons of intact germinating seeds. Visual growth differences among these treatments were also evident. The size and yellow color intensity of the fourth day treatments were shown to increase in the following order: detached cotyledon pairs alone, intact seedlings, detached cotyledon pairs in the presence of three excised axes. The growth of the hypocotyl and radical was also modified by removal of the cotyledons. These findings suggest that storage protein degradation and cotyledonal growth are controled by the axis. They also indicate that the cotyledons have some influence on the growth of the axes.

Time‐course studies were made on the hydrolysis of storage protein in the cotyledons of squash and on the distribution of the hydrolytic products during the germination of light‐ and dark‐grown plants. The storage protein was not hydrolyzed during the first 24 hours. It was hydrolyzed at a uniform rate from 1 to 5 days and at a slightly decreased rate from 5 to 7 days. Most of the hydrolytic products were transported to the axial tissue.

Proteinase activity in the cotyledons rapidly increased during germination to a maximum level at 2 to 3 days. This was followed by a decline to about the initial value after 7 days.
Effects of Supraoptimal Temperatures on Merulius lacrymans
Authors: Langvad Finn , Goksøyr Jostein
Published: April 2006

The growth rate of Merulius lacrymans (Jacq.) Fr. decreases very rapidly at temperatures above optimum (about 22°C). No growth occurred above 28°C. The thermal death‐time of the fungus at different temperatures above maximum was determined. At 37.5°C the thermal death‐time is 4 hours. At this temperature, the respiration is not directly affected, since an appreciable respiration occurred even after 6 hours. On the basis of 14C‐experiments and analysis of UV‐absorbing material excreted from the mycelium at supraoptimal temperatures, it is suggested that the detrimental effects of supraoptimal temperatures on this fungus include a degradation of the nucleic acids and a subsequent leakage of the nucleotides out of the cells.
Auxin‐stimulated RNA Synthesis in Oat Coleoptile Cells
Authors: Masuda Yoshio , Tanimoto Eiichi , Wada Shunji
Published: April 2006

Using oat coleoptile segments the following results were obtained.

Ten mg/l auxin (indole‐3‐acetic acid) increased the incorporation of uracil‐2‐14C and orthophosphate‐32P into RNA fraction during a relatively short incubation period. Stimulation of 32P incorporation due to auxin was found only in the region heavier than ribosomal RNA, probably in the messenger RNA region. The stimulation of uracil‐2‐14C incorporation into RNA caused by auxin was not influenced by the presence of 0.3 M mannitol which prevents osmotically the water absorption of cells. It is concluded that auxin primarily stimulates the biosynthesis of RNA, possibly messenger, in oat coleoptile cells.
14C‐Studies on Apple Trees. II. Distribution of Photosynthates from Top and Base Leaves from Extension Shoots
Authors: Hansen Poul
Published: April 2006

The photosynthates from leaves from extension shoots may be used either for new growth of the shoot itself, or for growth in other parts of the tree. An attempt has been made to elucidate this problem by determining the content of 14C in long shoots to which 14CO2 was applied either through fully developed leaves at the base, or through very young leaves at the apex.

In the case of 14C application at the base, 80 per cent or more of the 14C initially taken up disappears from the shoot, and only a very minor part is translocated upwards in the shoot. When the leaves at the apex are exposed, on the other hand, 80 per cent of the 14C absorbed is retained in the leaves and shoot components treated as long as there is still considerable terminal growth taking place, although a small percentage is deposited in the lower parts of the shoot. At the same time, a much higher proportion is incorporated into methanol‐insoluble components. As terminal growth decreases, a larger proportion of the 14C activity of the apex leaves also disappears from the shoot.

The distribution of activity between the sorbitol, sucrose, glucose and fructose fractions was not significantly different in young and in fully developed leaves. The 14C labelling in the sugar fraction was highest for sorbitol, then sucrose, but decreases with time compared to glucose and fructose.
Environmental and Genetic Control of Dormancy in Picea abies
Authors: Worrall John , Mergen François
Published: April 2006

The effects of temperature, photoperiod and chilling on the leafing‐out of Norway spruce, Picea abies (L.) Karst. were studied. High temperature promotes breakage of post‐dormancy, long photoperiods having no such effect. Photoperiod and chilling cause the breakage of true dormancy. However, under field conditions, photoperiod will have no effect on leafing‐out date in the spring.

By use of clonal material it was possible to show substantial genetic differences between individuals in response to temperature and photoperiod. When the effect of clones was accounted for, treatments could be compared more precisely. Differences between clones were apparent in heat‐sum required for leafing‐out, in rapidity of response to favorable post chilling conditions, and in chilling requirement This latter quantity was given a new definition, applicable when both chilling and post chilling temperatures are controlled and specified. This is that period beyond which a further 10 days of chilling accelerates leafing‐out by less than one day, i.e. the point at which the slope of the line relating days till leafing‐out to chilling period, is equal to minus 0.10.

Differences in leafing‐out date were shown between provenances taken from throughout the range of Picea abies. These differences were related to latitude with provenances of high latitude leafing‐out first.
Cytokinin Activity in Begonia and Bryophyllum
Authors: Heide Ola M. , Skoog Folke
Published: April 2006

Cytokinin activity has been obtained in ethanol extracts of Begonia and Bryophyllum plants. Begonia x cheimantha Everett yielded 30 to 300 μg kinetin equivalents per kg of fresh leaves in the tobacco callus bioassay. Short day conditions appeared to increase the extractable cytokinin content in the tissue.

Purification by fractionation on Dowex 50 H+ columns followed by organic solvent extraction, silver precipitation, and repeated paper chromatography yielded an apparently homogeneous product which accounted for most of the activity in the Begonia extracts. It was indistinguishable from zeatin in chromatograms developed with six solvent systems.

Other cytokinin active fractions were also obtained from both Begonia and Bryophyllum. Crystalline picrate preparations of active products were insufficient for identification by mass spectrometry.
Croissance et synthese des proteines de suspensions cellulaires de Tabac sensibles à la kinétine
Authors: Jouanneau Jean‐Pierre , Péaud‐Lenoël Claude
Published: April 2006

Culture conditions, allowing the unlimited growth and maintenance in shaken suspensions of a kinetin dependent strain of tobacco pith cells, were determined.

Cell clusters from 1 to 25 cells were selected from the cultures to study the cell multiplication after addition of specific growth factors to the basal medium. Cell division was found to be strictly dependent upon the presence in the medium of both kinetin and auxin. In complete medium the generation period was 45 to 49 hours.

Kinetics of the total protein synthesis in the cell suspensions have been measured either by estimation of protein nitrogen or by 35S incorporation into the proteins. After 3 days of culture, growth was exponential, as expressed by cell number or protein synthesis, which varied proportionally. Evidence was also found that the initial incorporation rate of radioactivity into the proteins was more rapid than expected from the increment of the protein net weight. It seems therefore reasonable to assume that a significant amount of protein turn over does exist during the initial period of growth. This phenomenon was observed even when no cell division occurred.

Kinetin significantly activated protein synthesis, whether or not auxin was present in the medium.
The Interrelation of RNA, Auxin and Auxin‐oxidases in Lentil Roots
Authors: Pilet P. E. , Braun R.
Published: April 2006

The correlation between auxin and RNA metabolism was investigated in lentil roots. IAA and NAA both cause a considerable rise in the RNA level of germinating lentil roots, though no effect of IAA was found on the DNA level. In untreated germinating roots various sections were isolated and a direct relation found between RNA and auxin content, and an indirect relation between RNA content and auxin oxidase activity.

In excised roots, incubated for 24 hours, the loss of RNA is paralleled by a loss of endogenous auxin. Excised roots treated with 10−4M IAA or M 10−4 NAA loose little RNA.

The findings suggest that in lentil roots the RNA levels may be controlled by auxin levels, which in turn may be controlled by the levels of auxin oxidase.
Effect of Different Gibberellins on the Growth of the Hypocotyl
Authors: Rai Vinay K. , Laloraya Manmohan M.
Published: April 2006

It has been stated earlier that hypocotyls of different plants show different growth response to added GA3. It was suggested that this difference may be due to the requirement of some specific gibberellin. Hence hypocotyl growth response of three groups of plants has been studied with different gibberellins: group one showing no or insignificant growth response, group two showing 150–200 per cent growth response and group three showing 300–500 per cent growth response to added GA3. Eight gibberellins were used, viz., GA1, GA2, GA3, GA4, GA5, GA7, GA8 and GA9, to test if this varying response is connected with the requirement of some specific gibberellin. In general, the results obtained do not favour this view. Iberis amara, a plant showing no response to added GA3, Dianthus sp., a plant showing 150 to 200 per cent response and Lactuca satwa, Antirrhinum majus and Nicotiana tabacum, plants showing 300 to 500 per cent response, were promoted by all the gibberellins tested to a similar extent as by GA3, with the exception of GA8 which was inactive in most of the cases.
Effects of Exudation on Ion Relationships of Excised Roots
Authors: Greeenway H.
Published: April 2006

In excised tomato roots submerged in solution, mannitol at –2.8 atm increased the phosphorus uptake and decreased the loss of previously absorbed phosphorus.

Separate collection of the xylem exudate demonstrated that these mannitol effects were due entirely to a reduced phosphorus flow via exudation. For example, in the case of previously absorbed phosphorus, the high loss of phosphorus at –0.3 atm could be contributed to phosphorus transport via the exudation stream, which was higher at –0.3 than at –2.8 atm. In contrast, loss from the root surface to the external medium was identical for the two different water potentials.

The neglect in measuring ion flow in the exudate might have confounded ion transport studies by other workers. Some particular cases were re‐examined, such as chloride uptake at high external concentrations and ion toss from different cell compartments.
Copper Oxidases in Thalli of the Liverwort Marchantia polymorpha
Authors: Poucke M. Van
Published: April 2006

A study is presented on the properties of copper oxidases in thalli of the liverwort Marchantia polymorpha L. Catecholase and ascorbic acid oxidase are compared in their specific activity, reaction kinetics, inhibitor sensitivity and intracellular localization. It is shown that catecholase is predominantly bound to particulate cell fractions and is normally inhibited by the usual inactivators of copper enzymes. Ascorbic acid oxidase activity, on the other hand, is strongest in the soluble protein fraction and is quite resistant toward the same inhibitors at the pH‐optimum of the enzyme. Both enzymes, when assayed with small tissue fragments, can be inhibited as expected.
A Theory for Circumnutations in Helianthus annuus
Authors: Israelsson D. , Johnsson A.
Published: April 2006

A theory is given for circumnutations in plants, especially hypocotyls of Helianthus annuus, which were used as experimental material

The theory is based on the lateral auxin transport, which arises when a gravitational force component acts on the plant. With a suitable time delay between stimulus and response, oscillations or circumnutations should arise. It is possible to describe these oscillation phenomena by the solutions of a differential equation, derived in this paper. The time delay has a central role in this equation.

The time delay is assumed to be identical with the geotropic reaction time for the hypocotyls. The ratio between the periodic time for the circumnutations and the reaction time for geotropic curvatures was found to be approximately constant in the temperature region investigated (namely 15–40°C), which supports the theory. Different methods of recording the circumnutations were used, 8 mm film camera technique being the most frequently employed.

The introduction of a weighting function for describing the plants “memory” of the stimulation makes it possible to relate the periodic time of the circumnutations to the reaction time for geotropic curvatures. The necessity of this weighting function as well as of the time delay in the equations is emphasized. An explanation of the “Fünfphasen‐bewegungen”, reported in the literature, is presented.
Photometrically Assayable Phytochrome in vivo in Callus Tissue Cultured from Nicotiana tabacum
Authors: Kasperbauer M. J. , Reinert R. A.
Published: April 2006

Phytochrome was photometrically detected in callus tissue cultured from tobacco stem pith. Our previous work with such tissues showed a growth response to red light, and a nullification of the effect of red by far‐red light. Tissues that were subcultured for 4 or 20 months were assayed. Tissues of the younger clone had the most detectable phytochrome. Also, tissues cultured in darkness and those exposed to 5 minutes of red light each day bad more detectable phytochrome than tissues grown under 16‐hour photoperiods of low intensity white light. We gratefully acknowledge Drs. H. A. Borthwick and J. E. Scheibe for use of facilities and assistance in operating the dual‐wavelength photometer at the U.S.Department of Agriculture Pioneering Research Laboratory for Plant Physiology at Beltsville, Maryland.
Indoleacetic Acid and Molecular Differentiation Evidence for Interaction
Authors: Sarkissian Igor V. , Spelsberg Thomas C.
Published: April 2006

Proteins of hypocotyls of bean were studied by electrophoresis. Proteins were extracted from hypocotyl segments of various stages of development starting with the relatively undifferentiated hook regions and proceeding by 2 cm segments down the hypocotyl. The proteins were the soluble (pH 7.4), the basic nuclear (histones), acidic ribonuclear and acidic chromosomal.

Soluble proteins reflected differentiation of the hypocotyl in that lower hypocotyl segments had more different protein types than did the hook region. Indoleacetic acid (IAA) at 10−6M when applied to the lower hypocotyl appeared to induce still more different proteins. However, at 10−3M, IAA appeared to induce molecular dedifferentiation in that hypocotyl protein patterns began to resemble those of the hook.

Histones also reflected differentiation, the hook having more histone types than the lower hypocotyl. IAA had no effect on histones.

The hook region had two types of acidic chromosomal proteins, the lower hypocotyl one. When lower hypocotyl segments were incubated in 10−3M IAA, the protein pattern resembled that of the hook in that the second protein normally present in the hook and not in the hypocotyl was in fact induced in the hypocotyl.

The hook had two acidic ribonuclear proteins, the lower hypocotyl one. IAA did not affect this protein.

These experiments suggest that IAA in some manner regulates molecular (protein) differentiation. It is further suggested that IAA accomplishes this control through the acidic nuclear proteins which are closely associated with genetic material and which reflect differentiation and are also affected by IAA.
Dependence of Lettuce Seed Germination on Actinomycin D‐resistant RNA Synthesis
Authors: Khan Anwar A.
Published: April 2006

The response of Grand Rapids lettuce half seed and intact seed to different nucleic acid and protein synthesis inhibitors was studied. 6‐azauracil, 2‐thiouracil and cycloheximide were strong inhibitors of germination of intact seed as well as of radicle elongation of half seed. Inhibition by 6‐azauracil and 2‐thiouracil was reversed by uracil but not by orotic acid, thymine or deoxycytidine. Actinomycin D and puromycin were ineffective suggesting that actinomycin D‐resistant RNA synthesis possibly controls both germination of intact seed and radicle elongation of half seed.

The requirements of RNA synthesis for the elongation of radicle in half seed in light and in the presence of gibberellic acid was the same. Such was not the case in the germination of intact seed which had different requirements of RNA synthesis in light and in presence of gibberellic acid. It is concluded that the mechanism of gibberellic acid and light in the intact seed germination, in so far as it involves the regulation of RNA synthesis, depends on the integrity of the seed coats.
Modification of Sex Expression in Muskmelon by Treatment with the Growth Retardant B‐995
Authors: Halevy A. H. , Rudich Y.
Published: April 2006

Treatment of an andromonoecious cultivar of muskmelon with N, N‐dimethylaminosuccinamic acid (B‐995) induced a shift towards femaleness. This tendency was expressed by a reduction in the number of staminate (male) flowers, an increase in the number of hermaphrodite flowers and a shift in flowering pattern resulting in the formation of hemaphrodite flowers at lower nodes.

The treatment also caused a change in the habitus of the plants from the regular pole type to a dwarf type, which was manifested by a marked reduction in node length and the suppression of tendril formation.

The mode of action of B‐995 on sex expression is discussed.
On the Mode of Action of Carbamate Herbicides
Authors: Keitt George W.
Published: April 2006

The hypothesis of Mann et al. that carbamate herbicides act as anti‐derepressor substances was tested in two systems: cell enlargement and proliferation in cultured tobacco pith, and auxin‐induced Avena first internode extension. Isopropyl‐N‐phenylcarbamate (IPC) and isopropyl‐N‐(3‐chIorophenyl carbamate (CIPC) both severely inhibited kinetin‐induced cell proliferation in tobacco pith at 10−6M. Auxin‐induced tobacco cell enlargement was inhibited to the same degree only at 10−3M. Avena internode extension was insensitive to these compounds in the range 10−3 to 10−7M of IPC and 10−4 to 10−8M CIPC. The results support but do not prove Mann's hypothesis. Results of various studies with carbamates are interpreted in terms of this mechanism.
Effect of Photoperiod, Auxins and Gibberellic Acid on Rooting of Stem Cuttings of Bryophyllum tubiflorum
Authors: Nanda K. K. , Purohit A. N. , Bala Adarsh
Published: April 2006

Photoperiod controls the initiation and development of roots on cuttings of Bryophyllum tubiflorum. Root initiation occurred when either the mother plant or the cuttings were exposed subsequently to SD conditions. Cuttings from LD plants exposed to LD did not root at all even after 4 weeks showing that short days are necessary for rooting of cuttings of this plant. The short day requirement can be substituted by IAA or IBA as roots were initiated in cuttings from LD plants when treated with the auxins under LD conditions. GA stimulates rooting of cuttings under SD conditions but does not replace the SD requirement. It failed to induce rooting under LD conditions.
Indoleacetic Acid‐Induced Decrease of the Ribomiclease Activity in vivo
Authors: Truelsen T. A.
Published: April 2006

A study has been made on the influence of indole‐3‐acetic acid (IAA) on the ribonuclease (RNase) activity in wheat coleoptile sections and green pea stem sections. The hormonal effects on the enzyme activity, ribonncleic acid (RNA) metabolism and growth have been compared.

Addition of 10−5M IAA to the plant sections causes their RNase activity to decrease and their elongation to increase. Removal of the added IAA results in increasing enzyme activity and decreasing growth. The altered enzyme activities are paralleled by opposite changes in the RNA net synthesis. Administration of crystalline RNase to the plant tissue depresses growth. There is thus evidence that the in vivo effect of IAA on the RNase activity is of importance for the hormonal regulation of RNA metabolism and growth.

The IAA‐induced reduction in the enzyme activity involves cellular metabolism. The effect can be suspended by means of p‐chloromercuribenzoate. A possible mechanism for the reduction is discussed.
Carboxydismutase Activity in Shade‐adapted and Sun‐adapted Species of Higher Plants
Authors: Björkman Olle
Published: April 2006

The activity of the photosynthetic enzyme carboxydismutase (ribulose‐l,5‐diphosphate carboxylase) was measured in leaf extracts of a number of higher plant species from habitats with greatly contrasting light intensities. Plants occupying sunny habitats and capable of light saturated rates of photosynthesis several times higher than those growing in the deep shade of redwood forests also have a considerably higher carboxydismutase activity. Thus, when expressed on the basis of total chlorophyll or even fresh weight, the enzyme activity is several times greater among the sun than among the shade species.

The comparatively low content of soluble protein in the shade plants indicates that their content of enzymes other than carboxydismutase also is low. Nevertheless, the activity of carboxydismutase even on the basis of soluble protein appears to be significantly higher in the sun than in the shade species.

It is concluded that low carboxydismutase activity probably is one of the factors that limit the capacity for light saturated photosynthesis in the shade plants.
Oxidative Enzymes and Pathways of Hexose and Triose Metabolism in Chlorella
Authors: Devlin Robert M. , Galloway Raymond A.
Published: April 2006

Cell‐free preparations of Chlorella pyrenoidosa Chick, van Niel's strain, were assayed for oxidative enzymes, utilizing isotopic and spectrophotometric techniques. The enzyme activity of heterotrophic and autotrophic cells was compared.

The study was divided into categories, one concerned with the spectrophotometric detection of enzymes involved in the initial reactions of glycolysis and the hexose monophosphate shunt, and the other with the direct oxidation of glucose as compared with that oxidized via glycolysis. The reduction of pyridine nucleotides in crude extracts was studied with glucose, glucose‐6‐phosphate, 6‐phosphogluconate, and fructose‐1‐6‐diphosphate as substrates. Enzymes detected in both heterotrophic and autotrophic cells were hexokinase, fructose‐diphosphate‐aldolase, NAD‐linked 3‐phosphoglyceraldchyde dehydrogenase, glucose‐6‐phosphate dehydrogenase, 6‐phosphogluconate dehydrogenase, and a NADP‐linked 3‐phosphoglyceraldchyde dehydrogenase.

In addition to isotopic studies designed to make an appraisal of the hexose monophosphate shunt, a comparison of the rate of reduction of NADP by glucose‐6‐phosphate and 6‐phosphogluconate in relation to the reduction of NAD by 3‐phosphoglyceraldehyde was made in light‐ and dark‐grown cells. The rate of reduction of NADP appeared to be lowered in the light‐grown cells, suggesting, as did also the isotopic studies, that the hexose monophosphate shunt is less active in autotrophic metabolism than in heterotrophic metabolism.
Pathways of Carbohydrate Catabolism in Senescent and Non‐senescent Tobacco Leaves
Authors: Baur J. R. , Halliwell R. S. , Langston Ruble
Published: April 2006

The pathway (s) of glucose degradation in detached senescent and non‐senescent tobacco leaves from plants approximately 100 days old were studied utilizing‘Relabeled carbohydrates. Comparable samples of each tissue were allowed to metabolize glucose‐1‐ and glucose‐6‐14C and C6/C1 ratios were computed from the radioactivity of 14CO2 collected. Two methods of calculation were compared.

Hexose monophosphate pathway activity was also compared in both ages of tissue by measuring 14CO2 respired from substrate ribose‐1‐, xylose‐1‐ and gluconic acid‐6‐14C.

The results indicate that the hexose monophosphate pathway accounts for approximately 25 percent of the respired CO2 in both senescent and non‐senescent tissues. Both types of tissue were equally efficient in degrading HMP shunt intermediates to CO2.
The Influence of Medium Composition and Additions of Animal Origin on the Formation of Capture Organs in Arthrobotrys oligospora
Authors: Nordbring‐Hertz Birgit
Published: April 2006

The formation of capture organs for nematodes in A. oligospora. and its dependence on substrate composition and additions of animal origin was studied in laboratory experiments. Variations in only the substrate composition did not give rise to capture organ formation. If nematodes were present, however, the medium composition was of great importance for the number of traps formed. Capture organs were not only formed in the presence of nematodes but also by addition of other taxonomically diverse animals such as earthworms, fly‐larvae and spring‐tails. The initialing factor is, for full effect, bound to the living state and not confined to nematodes. For biological control of nematodes with the aid of nematode‐trapping fungi, therefore, the effect of the other microfauna of the soil should also be taken into consideration.
Marine Plankton Algae Grown with Light‐Dark Cycles.
Authors: Paasche E.
Published: April 2006

The diatoms Ditylum brightwellii and Nitzschia turgidula were grown in semi‐continuous culture under various combinations of light intensity, temperature and daylength (photoperiod). Growth was strongly limited by light intensities below 0.03 cal/em2. min in both species. Above this intensity, light saturation of growth was rapidly approached in Nitzschia but only gradually so in Ditylum. The growth rate in continuous light was never significantly higher than with 16 hours of light plus 8 hours of dark. In Ditylum, continuous light above 0.03 cal/cm2. min caused a strong inhibition of growth at all temperatures. The chlorophyll concentration in the cells was greater the shorter the photopceriod. In cultures synchronised by different combinations of light intensity and photoperiod, cell division generally took place in the light. Synchrony was best under short photoperiods of bright light. Time courses are shown for chlorophyll synthesis and photosynthesis in synchronised cultures.
The Effect of Kinetin on Protein Level of Brassica Leaf Disks
Authors: Kuraishi Susumu
Published: April 2006

The senescent leaf disks from Brassica rapa L. were floated on a medium containing 14C‐L.‐leucine in the presence or absence of kinetin. The increase in radioactivity in protein fraction of kinetin‐treated disks was almost linear with time, while the increase in untreated disks incubated for 3 days started to slow down. The leaf disks were first incubated on the solution of 14C‐L‐leucine and then transferred to either kinetin solution or water in order to study whether the slower incorporation is due to the decreased rate of protein synthesis or that of protein retention. The decrease in radioactivity of disks floated on kinetin was slower than that of disks floated on water. The slower decrease in radioactivity caused by kinetin was not due to an increased turnover rate, since the same phenomena were observed in the presence of cold leucine or casein hydrolysate solution. These results suggest that kinetin retards the decomposition of protein in leaf disks and does not stimulate the synthesis of the bulk of protein.
Further Studies on Differentiation of Photosynthetic Properties in Sun and Shade Ecotypes of Solidago virgaurea
Authors: Björkman Olle
Published: April 2006

Measurements of the fraction of the incident light absorbed by diverse Solidago leaves revealed that differences in light harvesting capacity cannot explain the differences in efficiency of utilization of weak light in photosynthesis that have previously been shown to exist between sun and shade ecotypes when these have been grown in strong light and between identical clones of shade ecotypes when grown at different light intensities. Photosynthesis measurements at low and normal oxygen concentrations, provided no evidence that a different degree of inhibition of photo‐synthetic CO2 uptake by atmospheric oxygen is responsible for the observed differences in photosynthetic efficiency, at low or high light intensities. These results support the conclusion that the markedly less efficient use of weak light by shaded habitat clones grown in strong as compared with weak light is caused primarily by damage to the photosystems, or to a site close to them. Measurements of Emerson enhancement and of light‐induced absorbance changes provide some evidence that photoreaction II is more affected than I.

Enzyme extracts prepared from clones native to an exposed habitat were found to contain considerably higher activities of carboxydismutase (ribulosc‐l,5‐diphos‐phate carboxylase) than from clones native to a shaded habitat when the plants were previously grown at a moderately high light intensity. Exposed habitat clones apparently have a genetically determined, higher capacity to produce the carboxyla‐tion enzyme than shaded habitat clones. The high degree of correlation found when the light‐saturated rate of CO2 uptake in vivo of a number of individual Solidago leaves is plotted against the carboxydismutase activities found in the extracts of these same leaves suggests that low carboxydismutase activity is one of the intrinsic properties responsible for the low capacity for light‐saturated photosynthesis of clones from shaded habitats.

It is concluded from this and other investigations that differentiation between plants from habitats with contrasting light intensities, whether unrelated species or ecotypos of the same species, probably involves the capacity of several component steps of the photosynthetic process.
Studies on the Growth of Phaeodaetylum tricornutum
Authors: Hayward J.
Published: April 2006

The effect of a range of externally supplied carbon Compounds on the growth of Phaeodactylum tricornutum Bohlin in the dark and in the light has been studied. No substance tested was capable of supporting growth of the diatom in The dark and it appears that the organism is obligately phototropic. P. tricornutum is able to respire glucose, mannitol and lactate without the energy released being apparently available for growth. Some slight stimulation of growth occurs in The light and this appears to be partly due to the occurrence of trace element impurities in the organic compounds.
Gibberellin Biosynthesis: Genetic Studies in Gibberella fujikuroi
Authors: Spector Calvin , Phinney Bernard O.
Published: April 2006

Biochemical genetic studies on the production of gibberellins by the fungus Gibberella fujikuroi have identified two genes which control different steps in the biosynthetic pathway. One gene (g1) controls the production of all of the gibberellins: the second gene (g2) controls the production of GA1 and GA3 only.

Ascospores are not ordered in the ascus of this fungus. This apparent spore slippage precludes mapping of these genes to their respective centromeres.
The Systems I, II and III in the Photosynthetic Cycle of Electron Transfer
Authors: Lundegårdh H.
Published: April 2006

Two separate light reactions may be distinguished: (I) the reduction of ferredoxin and NADP probably by oxidation of carotene to xanthophyll; (II) the oxida tion of cytochrome f by chlorophyll (probably a). Reaction II implies a return of electrons to the pigments, system III, thus maintaining its normal steady state of oxidation‐reduction. The xanthophyll is hereby again reduced to carotene.

System I is sensitive to violet‐blue‐green and probably also infrared light. Carotene absorbs in these regions, ferredoxin in blue‐violet. System II is primarily sensitive to red light but also to blue‐violet. Both chlorophyll and cytochromes absorb in the latter region, the cytochromes also in green.

The response of systems I and II to different spectral regions was studied by means of a special spectrophotometric flash technique, enabling precise measure ments of the band‐height of the enzymes involved. The initial photic reactions of systems I and II, viz., the reduction of ferredoxin‐NADP and the oxidation of cyto chrome f show a full turnover in less than 0.1 ms but the transfer between systems I and II by means of which the cytochromes are reduced is slowed down to about 10−1‐10−2 s. The initial effect may thus be observed during ca. 0.1 s. At continuous illumination the displacement of the steady states of the enzymes may last up to several seconds and then return to a state of only partial reduction. Erroneous inter pretations of these phenomena are corrected.

In the blue‐sensitive system I ferredoxin alone mediates the reduction of NADP but the possibility of the presence of other factors capable of dark chemical elec tron transfer is discussed. In the red‐sensitive system II three cytochromes operate, viz., f, b3 and b6. Spectrophotometric evidence for the existence of two cytochromes b is presented. Cytochromes b6 and f are approximately synchronously oxidized and reduced, whereas b3 reacts somewhat independently. Cytochrome b3 probably acts as a decharger of OH− and compensates for the capture of H++ e− at the reduction of triphosphopyridine nucleotide (NAD) or of electrons by other oxidants.

The transfer of electrons between systems I and II maintains a reversible steady state of oxidation‐reduction that may be moved to one side or the other not only by monochromatic light but also in the dark under influence of N2, O2, the ratios NADP/NADPH and ADP/ATP, and various added substances. Spectrophotometric measurements in UV show that a flavoprotein participates in the multiple steady state.

The investigations illustrate many intricate technical problems that are too frequently overlooked. Photostructural reactions must be eliminated by referring band‐heights to an isosbestic level. The photosynthetic activity is strongly dependent on light‐scattering. Reliable measurements of cytochromes must be made in the α‐region owing to a strong interference of rapid changes of the ratio carotene/xanthophyll in the region of the γ‐bands.
Effect of CO2‐Concentration on the Accumulation of Starch and Sugar in Tomato Leaves
Authors: Madsen Erik
Published: April 2006

The carbohydrate content (starch, glucose and sucrose) in tomato plants grown in air Containing 0.04, 0.10, 0.15, 0.22, 0.32, or 0.50 vol. per cent CO2 was studied at 2 hours’ intervals over a period of 24 hours. The highest starch content was found at 0.22 vol. per cent CO2, while the highest content of soluble sugars were reached at a concentration of 0.10 vol. per cent CO2. A few observations of the morphogenic effects of carbon dioxide were also made.
Absorption, Translocation and Metabolism of 3‐Amino‐1,2,4‐triazole in Pinus ponderosa and Abies concolor
Authors: Lund‐Høie Kåre , Bayer David E.
Published: April 2006

The behaviour of amitrole (3‐amino‐l,2,4‐triazole) in 3‐year old seedlings of Pinus ponderosa (ponderosa pine) and Abies concolor (white fir) is described.

Visual symptoms of amitrole action appeared as a chlorosis of young needles, the extent of which varied with time and species. Maximum chlorosis was obtained when the application was made during the stage when no visible growth occurred. The greater susceptibility of ponderosa pine seedlings could be accounted for by the lower resistance to uptake of the herbicide into the needles and not by any difference between the conifer species in the metabolism of amitrole.

The translocation and metabolism of amitrole in the two conifer species are discussed. In both of the conifer species amitrole was converted into three metabolic products two of which were found to be identical with the previously described Unknown I and II.

Two types of treatment, on exposed phloem and on the needles, provided the possibility for a direct study of the site of amitrole metabolism. This site appeared to be in the stem.

Amitrole was the mobile, toxic compound in both species and was translocated in both symplast and apoplast. A circulation of the herbicide in the plant was observed. From the phloem amitrole diffused relatively slowly into the xylem, and during this lateral translocation part of the amitrole was metabolized. The rate of this detoxification process seemed to be dependent upon how fast amitrole moved from phloem to xylem and vice versa. This rate seemed to show a positive correlation with the intensity of the cambial activity. The translocation of amitrole to the roots was greatest when no visible growth could be detected.
Mise en evidence d'un RNA ribosomal de faible poids moleculaire dans les jeunes germinations de Raphanus sativus et de Phaseolus vulgaris
Authors: Vedel F. , Guitton Y.
Published: April 2006

Un RNA ribosomal de faible poids moleculaire, distinct du RNA de transfert et analogue à celui qui a été identifie dans les cellules bactériennes et dans certaines cellules animates, a été mis en evidence chez les végétaux. Ce RNA ribosomal de faible poids moléculaire a été séparé du RNA de transfert. Les résultats sont discutés en relation avec des hypothèses récemment émises sur le rôle de ce nouvel RNA.
Chlorophyllous Nature and Growth Characteristics of Teratoma and Habituated Tissue Cultures of Tobacco
Authors: Chen Peter K. , Venketeswaran S.
Published: April 2006

The growth characteristics of three types of tissue cultures of tobacco have been investigated. They are (i) pigmented and differentiated teratoma tissue; (ii) pigmented and non‐differentiated habituated tissue and (iii) non‐pigmented and non‐differentiated habituated tissue. All the tissues were grown on a 10 × White's medium without any exogenous supply of auxin.

The comparative growth rate of the tissues was related to their nature of differentiation, viz., either organelle differentiation with chloroplast or organ differentiation with buds, leafy appendages, etc. Teratoma and pigmented habituated tissues had normal chlorophyll and carotenoid contents and showed more favorable growth in light than in the dark. The pigmented tissues showed a higher protein content than the non‐pigmented tissues irrespective of whether they were of tumorous or normal origin. The pigmented tissues showed less dependence on sucrose availability in the medium than the non‐pigmented tissues. Recovery after sucrose starvation was higher in the pigmented tissues than in the non‐pigmented tissues.

The results indicate that the growth rate of highly differentiated tissues is much slower than non‐differentiated tissues and that the pigmented tissues photosynthesize and survive on reserve food products manufactured as a result of photosynthetic activity.
The Influence of CO2 on the Metabolism of Rhizome Tissue in Iris pseudacorus
Authors: Bown A. , Boulter D. , Coult D. A.
Published: April 2006

In vitro experiments showed that concentrations of CO2 above 6 per cent inhibited succinate oxidation; 30–10 per cent of succinate oxidation may be blocked in the presence of 12 per cent CO2.

Storage of rhizome cores in CO2 increased the levels of all the main acids except malic. The amino acids, aspartate, glutamate and alanine, also increased in amounts under these conditions.

Cores fix CO2 probably via the reaction phosphoenolpyruvate to oxaloacetate. Raised CO2 levels increased the rate of diminution of carbohydrate, but carbon itself was conserved due to a reduction in CO2 output.
Application of a Theory for Circumnutations to Geotropic Movements
Authors: Johnsson Anders , Israelsson Donald
Published: April 2006

From a previously published theory (Israelsson and Johnsson 1967) for circumnutations in Helianthus annuus it is possible to predict the geotropical curvatures of the hypocotyls. This extension of the theory is given in the present paper and some geotropical experiments are performed and discussed.

The agreement between the theory and the experiments has been verified in the case of gravitational stimulation during relatively short stimulation periods, in the case of continuous gravitational stimulation, etc. Restrictions in the proposed model are discussed.
Carbonic Anhydrase in the Marine Alga Ulva pertusa
Authors: Ikemori M. , Nishida K.
Published: April 2006

The preparation of stable samples containing carbonic anhydrase from Ulva pertusa was achieved by using artificial sea water and 10 mM cysteine solution adjusted to pH 8.2 instead of 10 mM cysteine solution alone. When the sample was stored at 0°C in darkness the enzyme activity was retained for about 24 h. In contrast to the results obtained with land plants in previous works a remarkable inhibitory effect of low concentrations of sulfanilamide and Diamox (2‐acetylamino‐1,3,4‐thiadiazole‐5‐sulfonamide) on the activity of the enzyme was observed.
Response of Pusa Seedless Grape to 4‐CPA, Kinetin, Uracil and GA
Authors: Dass H. C. , Randhawa G. S.
Published: April 2006

Response of Pusa Seedless, a cultivar of Vitis vinifera to 4‐chlorophenoxyacetic acid (4‐CPA), kinetin, uracil and gibberellic acid (GA) separately and in combinations was tested. Dipping the clusters in GA at 50–100 mg/1 at 2–3 days after full bloom significantly increased the bunch and berry weight of Pusa Seedless Grape. 4‐CPA and uracil treatments increased the bunch and berry weight to some extent but not as effectively as GA treatments and kinetin had no effect. GA proved to be the best in increasing the berry weight of this cultivar. A synergistic effect was observed when 4‐CPA was combined with GA at 50 mg/1 but combinations of 4‐CPA with higher concentrations of GA did not show such synergistic effect. In general, GA alone and especially in combination with 4‐CPA lowered the quality of the berries. Uracil on the other hand, improved the quality when applied alone and in combination with GA.
Growth and Geotropic Responses of Avena Coleoptiles to 4‐Amino‐3,5,6‐Trichloropicolinic Acid
Authors: Schrank A. R.
Published: April 2006

The elongation and geotropic responses of coleoptile sections of Avena sativa L. to various concentrations of 4‐amino‐3,5,6‐trichloropicolinic acid (Tordon) proved to be qualitatively similar to those previously reported for 2,3,6‐trichlorobenzoic acid (TCBA). Tordon stimulated growth in a range of concentrations from 1 × 10−6 to 1 × 10−4M but higher concentrations were inhibitory. Geotropic curvature was extensively depressed by 1 × 10−5 and 1 × 10−4M Tordon, concentrations which accelerated elongation. A similar differential effect has been reported for TCBA and other auxins. Several other picolinic acids and related compounds were tested, but only very slight responses were noted.
Der Einfluss der Phosphatversorgung sowie die Wirkung von ionogenem und chelatisiertem Zink auf die Zink‐ und Phosphataufnahme einiger Schwermetallpflanzen
Authors: Ernst Wilfried
Published: April 2006

In physiologischen Untersuchungen an Schwermetallpflanzen wurde die hohe Zinkverträglichkeit für Silene cucubalus var. humilis bestätigt und für Thlaspi alpestre ssp. calaminare neu festgestellt.

In Wasserkulturversuchen mit Silene cucubalus var. humilis wirkte Zinksulfat bereits bei einer Gabe von 100 mg Zn/1 im Verlauf einer Vegetationsperiode toxisch. Hingegen wurde Zink‐Chelat noch bei einer Konzentration von 600 mg Zn/I ertragen. Durch Chelatgaben kann demnach die Zinkverträglichkeit der Schwermetallpflanzen wesentlich erhöht werden.

Die untersuchten Schwermetallpflanzen Silene cucubalus var. humilis, Armeria maritima ssp. halleri und Cardaminopsis halleri nahmen wesentlich mehr Zink aus einer zinksulfathaltigen als aus einer zinkchelathaltigen Nährlösung auf. Dabei dürfte die toxische Grenze durch die in den Sproß gelangte Zinkmenge bestimmt werden. Die Toxizitat scheint dann erreicht zu sein, wennsich bei hoher Gesamtaufnahme über 80% des Zinks im Sproß befinden.

Zwischen dem Zink‐ und dem Phosphatgehalt der Sprosse ergab sich in den Zink‐sulfatreihen eine negative Korrelation, die jedoch für die Zink‐Chelatreihen nicht bestatigt werden konnte.
Photomorphogenic and Chlorophyll Studies in the Bryophyte Marchantia polymorpha
Authors: Fredericq H. , Greef J. De
Published: April 2006

The action of daily far‐red (FR)‐irradiations at the end of photoperiods of white fluorescent light was studied on orientation and chlorophyll content of green thalli of Marchantia polymorpha L. By the end of the night following the first FR‐exposure, the chlorophyll content of the tips was already significantly lower than that of the controls, and there was a beginning of upward growth; by the end of the next 8‐hour photoperiod and still before the second FR‐irradiation, both the change in orientation and the pigment drop had become much more pronounced.

After one week, a terminal 5 min FR treatment had resulted in 20 to 30% less chlorophyll for the tips after 8‐hour days, and in ±10% less after 16‐hour days; the morphogenic effects were also stronger after 8‐hour than after 16‐hour days. After three weeks under 8‐hour photoperiods, the tips of the FR‐treated thalli contained ±⅓ less chlorophyll than the tips of the controls; for the basal parts of the thalli the drop was smaller. However, after 1‐hour photoperiods, FR depressed the level of the basal parts much more than that of the tips: after one week 1 min FR caused a diminution of 20 to 30 per cent; a daily irradiation of 5 min caused a drastic bleaching, with 60 to 70 per cent less chlorophyll α than in the controls. The various FR‐effects were always fully reversed by 2½ min R light. The results are interpreted in terms of the R, FR phytochrome‐mediated system. The FR‐induced change in orientation is thought to be linked to active growth. The FR‐induced chlorophyll decrease can be explained by an effect on the regeneration of protochlorophyll as proposed for etiolated seedlings by several authors, but some of our data indicate the possibility of a greater chlorophyll catabolism in FR‐treated than in control thalli.