bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further Studies on Differentiation of Photosynthetic Properties in Sun and Shade Ecotypes of Solidago virgaurea
Authors: Björkman Olle 
Published: April 2006

AbstractMeasurements 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

AbstractThe 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

AbstractBiochemical 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

Abstract

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

AbstractThe 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

AbstractThe 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

RésuméUn 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

AbstractThe 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

Abstract 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

AbstractFrom 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

AbstractThe 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

AbstractResponse 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

AbstractThe 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

ZusammenfassungIn 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

AbstractThe 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.
The Comparative Boron Nutrition of Several Green and Blue‐Green Algae
Authors: Gerloff G. C. 
Published: April 2006

AbstractThe boron requirements of filamentous and non‐filamentous species of green and blue‐green algae have been investigated. A primary feature of this study was the quantitative analysis of the cells for boron. This permitted expression of the degree of purification of the environment and the boron requirements of the organisms in terms of cell content. Three species of green algae were shown neither to require boron nor to absorb it in appreciable amounts. In contrast, three species of blue‐green algae readily absorbed boron and nitrogen fixing species showed a marked growth response to boron when nitrate was omitted from the culture medium. The response to boron was less with nitrate in the medium, probably due to increased contamination from the nitrate salt rather than an involvement of boron in the fixation process. The boron content of the deficient blue‐green algae was 1–2 μg/g, suggesting a requirement below dicot angiosperms and comparable to monocots. In agreement with other reports, the fungus Penicillium chrysogenum neither required nor absorbed boron.
Occurrence and Metabolism of Indoleacetaldehyde in Certain Higher Plant Tissues Under Aseptic Conditions
Authors: Rajagopal R. 
Published: April 2006

AbstractQualitative and quantitative evidence based on thin‐layer chromatography and the Avena curvature test respectively, are presented for the normal and natural occurrence of indoleacetic acid (IAA), indoleacetaldehyde (IAAld) and tryptophol in the etiolated shoots of Pisum sativum, grown, harvested and extracted under aseptic conditions. Non‐aseptic pea shoots contain much more IAA and IAAld than aseptic ones. Extraneous contribution to the indole pool of pea plants grown under non‐sterile atmosphere, other than by the inherent agency of the plant itself, is therefore not excluded.Indoleacetaldehyde metabolizing activity of the tissues and cell‐free preparations of etiolated Avena seedlings, leading to the production of IAA and tryplophol, is unaffected by the antibiotics actinomycin and streptomycin over a wide range of concentrations. Formation of IAA from IAAld is suppressed by a small degree (10 to 15 %) by chloramphenicol. But this antibiotic does not influence the concurrent production of tryptophol. It is deduced that epiphytic bacteria play little role in the transformation of IAAld to IAA and tryptophol by Avena tissues.
Shoot Formation in Tissue Cultures of Chrysanthemum‘Bronze Pride’
Authors: Hill G. P. 
Published: April 2006

AbstractExplants of Chrysanthemum stem were cultured on four different media on all of which callus was produced. This callus and explant tissue was then sub‐cultured on to one of two media, making eight different treatments. One of these treatments in which explants were cultured on a medium containing 2 mg/1 1‐naphthaleneacetic acid (NAA) and 0.8 mg/1 kinetin, and then sub‐cultured onto a medium containing 1 mg/1 kinetin and 1 g/1 soya peptone produced numerous shoots. The value of this finding for the propagation of chrysanthemum is discussed.The technical assistance of Helen Krebs, Sheila Bruce and Maria Bagnall is acknowledged. I also thank Dr. J. L. Bailey for discussions and encouragement.
The “Point of no Return” Concept in Cell Division. The Effects of Some Metabolic Inhibitors on Synchronized Chlorella pyrenoidosa
Authors: Moberg Sidsel , Knutsen Gjert , Gokøyr Jostein 
Published: April 2006

AbstractThe coarse of growth and cell division in synchronized cultures of Chlorella pyrenoidosa was studied after the addition of metabolic inhibitors at differing times during the cell cycle (14 h light ‐ 10 h darkness with nitrate as nitrogen source. 12 h light: 12 h darkness with urea as nitrogen source).Dinitrophenol (DNP) added to a final concentration of 0.3 mM at any time in the synchronization cycle, the compound remaining in the suspension from the time of addition to the end of the dark period, inhibited spore formation completely. Growth measured as increase in cell volume was less sensitive to the action of the inhibitor. Chloramphenicol (CAP) added dining the 0–5 h interval to a final concentration of 0.1 mM resulted in 80 per cent inhibition of cell division. Similar treatment started at successive times thereafter resulted in a gradual decrease of the inhibition. Treatment at the 14th hour and during the dark period did not affect the sporulation.Similar experiments with 0.9 mM puromycin added at various times during the illumination period gave almost complete inhibition of cell division, while the growth was reduced by only 25 per cent. para‐Fluorophenylalanine (p‐FPhe) at 3.3 × 10−2 mM stopped cell division nearly completely irrespective of addition time in the light period. Addition during the dark period also prevented an increase in the number of tree cells. In this case about half of the cells produced spores which were not released.It is concluded that DNP inhibits all stages of preparation for cell division, as well as the division process itself. With CAP a genuine transition point of preparation for cell division was observed, although its interpretation as related to protein synthesis is somewhat uncertain. With puromycin and p‐FPhe no transitions were observed.