bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Light on Nitrate and Nitrite Assimilation by Chlorella and Ankistrodesmus
Authors: Morris L , Ahmed J. 
Published: April 2006

AbstractLight stimulates the assimilation of nitrate and nitrite by two green algae, Chlorella pyrenoidosa and Ankistrodesmus braunii. Assimilation can be observed when the algae are illuminated in the absence of carbon dioxide under both aerobic and anaerobic conditions. The rates of assimilation by Chlorella do not depend on the presence of carbon dioxide, but Ankistrodesmus assimilates nitrate and nitrite more rapidly when cultures are illuminated in the presence of carbon dioxide than in its absence.The ratios of O2: NO3′ and O2: NO2′ vary from one experiment to the other and, with the exception of Chlorella cultures reducing nitrite they are higher than the ‘expected’ values of 2.0 and 1.5 respectively.Oxygen evolution accompanying nitrate and nitrite by algae illuminated in the absence of carbon dioxide is completely inhibited by DCMU at concentrations of 4 × 10‐6 M. However, nitrite assimilation by both Ankistrodesmus and Chlorella and nitrate assimilation by Ankistrodesmus are less sensitive to the inhibitor.
Inhibition of Nitrogen‐Fixing and Nitrifying Bacteria by Seed Plants
Authors: Rice Elroy L. 
Published: April 2006

Abstract Euphorbia suinna occurs in the pioneer weed stage of succession in abandoned fields in several midwestern states of the United States. It was previously found to be very inhibitory to several test strains of nitrogen‐fixing and nitrifying bacteria and to several associated seed plants. The present project was concerned wilh the identification of the chief inhibitors produced by that species, using appropriate column and paper chromatographic techniques, and by tests of bacterial inhibition employing the diffusion technique on solid media. Three hydrolyzable tannins were consistently isolated from extracts of the species. All three tannins and purified reagent tannic acid from at least two commercial sources yielded ellagic acid, gallic acid, and glucose on hydrolj'sis by acid or tannase. All yielded one or more additional phenolics which were not identified. The tannins from E. supina were all slightly different from each other and from commercial reagent tannic acid as indicated by different Rf's on paper, elution sequence from polyamide columns, and relative amounts of glucose, ellagic acid and gallic acid produced on hydrolysis.
An Interaction between the Effects of Kinetin and Gibberellin in Retarding Leaf Senescence
Authors: Back A. , Richmond A. 
Published: April 2006

AbstractThe relation hetween the effects of kinetin and gibberellin on retardation of leaf senescence was studied. Leaf discs were incubated for five days in several hormone concentrations, the chlorophyll was extracted and its amount estimated spectrophotometrically. Investigation of leaves from actively growing plants of Taraxacum megalorrhizon and Tropaeolum majus showed that an interaction existed between the effect of both hormones. Leaf age, light intensity and day length had a marked effect on the degree of response to the hormonal treatments, hut the change in response effected by these conditions remained similar for both hormones. Possible interpretations of the interaction observed between the effects of kinetin and gibberellin are discussed.
Pathways of IAA Production from Tryptophan by Plants and by Tbeir Epipbytic Bacteria: a Comparison
Authors: Libbert Eike , Drawert Anneliese , Schröder Roswitha 
Published: April 2006

AbstractUnder nonsterile conditions, IAA can be extracted from pea stem sections infiltrated with buffer, IAA, or tryptophan. This IAA has microbial origin, since its occurrence is prevented by antibiotics. All infiltrated IAA disappears in the sections. Under sterile conditions, several inhibitors of IAA oxidase prevent the complete disappearance of infiltrated IAA. Some of them permit, by preventing the disappearance of produced IAA, the formation in vivo of extractable IAA amounts from tryptophan. This IAA production is further increased by pyridoxal (phospbate), and by α‐ketoglutarate.
Phase‐shift in Geotropical Oscillations – A Theoretical and Experimental Study
Authors: Johnsson A. , Israelsson D. 
Published: April 2006

AbstractGeotropically induced phase‐shifts in circumnutations of Heliauthus annuus hypocotyls are studied. – Theoretical deductions from a previously developed theory for geotropical movements are made for the case of a short gravitational stimulation in different phase positions of an oscillating hypocotyl. – Experimental studies are performed to test the theoretical results. – The conclusions are drawn, that the theory mentioned can satisfactorily describe geotropically induced phase‐shifts. A comparison with phase‐shifts in photoperiodic systems is made.
An Investigation of Bidirectional Translocation in the Phloem
Authors: Peterson CarolA. , Currier H. B. 
Published: April 2006

AbstractPatterns of 14CO2, assimilate movement in Vicia jaba plants having 7 nodes were studied. Bidirectional translocation occurred throughout most of the stem length when tracer was applied to leaves of various ages. To determine whether this bidirectional translocation occurs within single sieve tubes, a O.1 % solution of the fluorescent dye K‐fluorescein was applied to a lightly scraped area on the stem in the middle of a young internode. After one hour the dye was present short distances above and below the treated area. Free‐hand sections of the internode showed the dye to be localized in the traces of the larger leaves below tbe treated area and in the traces of the younger leaves above the treated area. The dye was never present in the same bundle both above and below the treated area, indicating that each bundle and sieve tube translocated the dye in only one direction. These results were confirmed using Phaseolus vulgaris, Vinca rosea, and Pelargonium hortum. A similar study in which petioles of young Ecballium elaterium leaves were treated showed that usually the phloem of one bundle translocated the dye in only one direction but in some cases the external phloem of the bicollateral bundles carried the dye toward the stem while the internal phloem carried the dye toward the blade. When longer time intervals were used in all these experiments, the dye sometimes appeared in the same phloem areas both above and below the treated area. This is explained by a lateral transfer of tracer within the phloem, either through secondary phloem or through bundle anastomoses at the nodes.
Callus Cultures of Tomato Mutants
Authors: Ulrich Jane M. , Mackinney G. 
Published: April 2006

AbstractCallus from hypocotyl, stem, and fruit tissue of tomato mutants was grown on a complex pea extract medium. The genotypes responded differently to the levels of nutrients and stimulators or inhibitors in the medium. Hypocotyl callus of yellow (r) tomato required K2SO4 for quick establishment and continued steady growth for several months; callus of this mutant could also grow with 0.5 % dimethyl sulfoxide in the medium, although growth was less than the control. The red ghost (r+gh) mutant is sensitive to a toxic component in the pea extract, and makes its best growth with the standard minerals and vitamins, but in 1/2 concentration pea extract plus 5 % coconut water. Tangerine (t), red lutescent stem (r+l2), and r+gh are mutants which respond differently to thiourea: t grows about the same at all concentrations, r+gh grows best at low thiourea, and r+l2 grows best at the specific level of 20 mg/l thiourea. The recent active t or r+l1 and r+l2 isolates require supplementary auxin to which the older, slow‐growing isolates do not respond. However, there is variation in growth response of different isolates of the same mutant. The several red (r+) cultures are similar in their slow growth, but somewhat different in responses to specific nutrients. The recent + isolate is one of the most active cultures, in comparison to the slow growth of t callus isolated in 1964. It is therefore concluded that growth is affected both by the specific requirements of the mutant and by the age and vigor of isolates.
Influence of Light on Germination of Pinus palustris Seeds
Authors: McLemore B. F. , Hansbrough Thomas 
Published: April 2006

AbstractRed light with a wavelength of 660 nm promotes germination of longleaf pine (Pinus palustris Mill.) seeds, and far‐red light (730 nm) inhibits germination. The promotion‐inhibition process is repeatedly reversible, indicating that germination is controlled by the photoreversible reaction of phytochrome. Response varied greatly between single‐tree lots and was dependent on the length of time seeds were imbibed at 5°C. Dry seeds did not respond to light treatments when they were subsequently imbibed and tested in darkness. Stratification for 28 days essentially removed the light requirements for germination.
The Adaptation of Plankton Algae
Authors: Jøsrgensen Erik G. 
Published: April 2006

AbstractThe variation in Skeletonema cells grown at 3 klux continuous illumination and 20°C is reported. Four different types of lamps gave no difference in the photosynthetic characteristics. The average diameter of the cells decreased from 8–3.5 μ during their six months vegetative period. The ratio between the pigment content in the largest and the smallest cells was about 2:1. A good correlation between cell volume and chlorophyll a content was found for this species. The content of chlorophyll c generally varied between 4 and 17 per cent of the chlorophyll a content. — A distinct correlation between the chlorophyll a content and the rate of photosynthesis per unit of cells at low light intensity was found. The rate of photosynthesis, in mg C per mg chlorophyll a and hour at 1 klux, varied between 0.40 and 0.70 for all 60 experiments with an average value of 0.56. The corresponding value for cells deficient in phosophorus was 0.19 and for cells deficient in nitrogen 0.09. — The material also showed a good correlation between the rate of photosynthesis per cell at 1 klux and the light‐saturated rate of photosynthesis. Ik varied between 7 and 13 klux.
The Chemical Induction of Supernumerary Shoots in the Developing Embryos of Wheat
Authors: Ferguson J. D. , McEwan J. M. 
Published: April 2006

AbstractThe induction of seedlings with multiple shoots by the in vivo treatment of embryos of wheat by herbicides such as 2,4‐D, 2,4,5‐T, MCPA and TBA as well as mixtures of these substances was studied. Treatment during the first week of embryo development was necessary for the production of additional shoots in the seedling; later treatment gave rise to callused seedlings. Other seedlings such as oats, barley and rye, and other species of wheat were treated, but seedlings with extra shoots were not produced, though callused seedlings were recovered.
Über den Einfluss hypotonischen Milieus auf den Stoffwechsel dereprimierter pflanzlicher Gewebe
Authors: Lange Horst , Kahl Günter , Rosenstock Günter 
Published: April 2006

AbstractDuring investigations of their metabolism fragments of plant tissue are most commonly incubated in watery solutions in order to replace the conditions within the intact organ approximately. — This paper reports experiments performed to investigate the influence of a hypotonic medium on several parameters of importance in cell metabolism (protein synthesis, enzymatic activity, concentrations of metabolic intermediates, respiration and cell division). — It could be shown that protein synthesis is severely inhibited in hypotonically exposed potato tuber discs. As a consequence the activities of two dehydrogenases of the pentose phosphate shunt (glucose‐6‐phosphate‐ and 6‐phosphogluconate‐dehydrogenase) are very low as compared with tissue in air. Since the activated pentose shunt evidently contributes to the respiratory reaction after derepression of the tissue, lowered activities of these dehydrogenases must consequently result in lower respiratory activity. This is actually realized in washed tissue. Likewise the mitotic activity is inhibited to a considerable extent. — The destruction of permeability barriers within the cell as a consequence of slicing causes leakage of a variety of metabolites such as glucose, glucose‐6‐phosphate, fructose‐6‐phosphate and pyruvate. Thus leaching of metabolic active substances is certainly one of the causal factors in the complex reaction of tissue slices exposed to a hypotonic medium, although such important parameters as changed gas conditions and the various effects of altered hydration of cell cytoplasm must be considered.
Callus Cultures of Tomato Mutants II. Carotenoid Formation
Authors: Ulrich Jane M. , Mackinney G. 
Published: April 2006

AbstractCarotenoid synthesis in the fruit of tomato mutants is under gene control. Since undifferentiated plant cells are presumably totipoltent, the callus tissue should be able to produce the carotenoids typical of the genotype. The carotenoids of masses of callus derived from hypocotyls of the red ghost and tangerine tomatoes were extracted and characterized by means of column and thin layer chromatography, chemical and spectral properties. The red ghost callus contained predominantly phytoene and phytofluene; the tangerine callus had primarily ζ‐carotene and prolycopene. Thus under our cultural conditions, carotenoids typical of the fruit rather than the leaf were produced, albeit in much reduced quantities.
Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism
Authors: Libbert Eike , Manteuffel Renate 
Published: April 2006

AbstractMore “diffusible” auxin is received from nonsterile than from sterile corn coleoptile tips. An artificial reinfection of sterile coleoptiles with epiphytic, IAA‐producing bacteria strains does, a superinfection of nonsterile coleoptiles does not increase the auxin amount. The difference between sterile and nonsterile tips persists if diffusion from the coleoptile surface is excluded by covering the surface with a paraffin layer. The greater the distance from the apex, the higher becomes the superiority of nonsterile tips. An artificial bacterial contamination of the contact face between tip and receiver agar block, or addition of glucose and tryptophan to the agar block, do not influence the received auxin amount. Consequently the additional, bacteria‐produced auxin delivered by the nonsterile tip is not produced at the cut surface or in the agar but is present in the tissues of the coleoptile tip.
Seasonal Changes in Auxin Effects on Rooting of Stem Cuttings of Populus nigra and its Relationship with Mobilization of Starch
Authors: Nanda K. K. , Anand V. K. 
Published: April 2006

AbstractStem cuttings of Populus nigra were treated with 10 and 100 mg/1 each of IAA., IBA, 2,4‐D and NAA at one month intervals and observations were recorded for the morphophysiological status of the branches, their starch content and their rooting response. — The first phase characterized by delayed, short and scarce roots and the high starch content of cuttings coincided with the onset of winter dormancy in November lasting through February. It was followed by a phase of vigorous rooting and low starch content of cuttings coinciding with the renovation of growth activity in February lasting through October, except in April and May when rooting was more or less completely nullified. — The poor rooting in winter was caused by low activity of hydrolyzing enzymes not mobilizing starch into soluble sugars; and profuse rooting during active growth period by high activity of hydrolyzing enzymes caused by endogenous auxin, resulting in mobilization of reserved food materials necessary for the initiation and development of roots. The low rooting in April and May is ascribed to the fact that bulk of the mobilized food was used up in the growth of sprouted branches leaving very little for rooting when these cuttings were planted. — The seasonal changes in the effectiveness of exogenously applied auxins also appear to be related with the level of endogenous auxin. In June endogenous auxin was high due to high meristematic activity, the exogenously applied auxins raising it to supra‐optimal levels that were inhibitory. On the other hand, in October exogenously applied auxins enhanced rooting by raising it to an optimal level as the production of endogenous auxin had been decreasing gradually due to lowering temperatures. — The results demonstrate that auxin effect on differential rooting with season in this plant is determined by the physio‐morphological status of the branches that govern the production of endogenous auxin and is mediated primarily through its effect on mobilization of reserve food materials caused by enhanced activity of hydrolytic enzymes.
The Mechanism of Boron Immobility in Plants
Authors: Oertli J. J. , Richardson W. F. 
Published: April 2006

AbstractA mechanism is postulated to explain the immobility of boron in plants, i.e., the absence of any significant retranslocation of this element from one leaf to another. It is shown that boron readily enters the bark and is translocated within the bark. Since it has also been shown that boron remains water‐soluble in plants, the immobility cannot be explained through a chemical fixation, lack of entry into phloem, or absence of phloem transport. Rather, boron enters the phloem in leaf margins where concentrations are high, is transported in these conduits, is lost therefrom where the xylem concentration is low, i.e. in basal areas of the leaf and in petiole, is transported back in the xylem and accumulates in terminal place of the transpiration stream. A high local mobility of boron, together with the essentially unidirectional flow of the transpiration stream, thus cause a cyclic movement of B and prevent the efflux of this nutrient; this explains the immobility over long distances.
Effect of 2,4‐D on Cell Wall Metabolism of Peroxyacetyl Nitrate Pretreated Avena Coleoptile Sections
Authors: Ordin Lawrence , Garber Morris J. , Kindinger Juanita I. 
Published: April 2006

AbstractAvena coleoptile sections were exposed to nonlethal concentrations of peroxyacetyl nitrate (PAN). The sections were then incubated in solutions of 50 mM glucose plus 2.5 mM poassium phosphate with various concentrations of 2,4‐dichlorophenoxycetic acid (2,4‐D). Growth after 4 hours was measured. A corresponding series of experiments was carried out with glucose‐14C (U) in the subsequent incubation medium and the effect of the 2,4‐D treatments on 14C incorporation into various cell wall components was determined. Growth in the PAN‐treated sections, although still partially inhibited, was greater at auxin levels normally superoptimal for growth than at the former optimum. Incorporation into all cell wall fractions was similar to growth in the case of control treated tissue. Most of the cell wall constituents, but particularly cellulose and less soluble noncellulosic polysaccharides, tended to show higher incorporation at the levels where PAN‐treated growth was also higher. It was concluded that effects by PAN on cell wall metabolism in growing tissue are similar to the effects on growth and that the mechanism of alleviation of growth inhibition is probably through decreased inhibition of wall metabolism.
Differentiation ex ovulo of Embryos and Plantlets in Stem Tissue Cultures of Tylophora indica
Authors: Rao P. S. , Narayanaswamy S. , Benjamin Bathsion D. 
Published: April 2006

Abstract Tylophora indica callus tissue repeatedly subcultured every month on a series of different nutrient media in sequence regenerated roots, shoots and typical, bipolar embryos in vitro from unorganized callus parenchyma. The embryo‐like structures developed from somatic cells grew into normal plantlets when isolated and cultured on appropriate milieu of nutrients and hormones bypassing the normal sexual method of reproduction. Likewise, free cells in suspension also passed through embryonic stages reminiscent of development from fertilized egg.
Root‐promoting Substances in Salix alba
Authors: Kawase Makoto 
Published: April 2006

AbstractRoot‐promoting substances were extracted from softwood cuttings of Salix alba L. by centrifuging them with water or by shaking the ground freeze‐dried stems with water. Rooting substances were partitioned by paper chromatography or chemical fractionation and their rooting activity was tested by mung bean cuttings. Both extracts indicated three major root ‐promoting fractions at Rf 0‐0.1, 0.7‐0.8, and 0.3‐0.4 in a decreasing order of their activities when paper chromatographed with isopropanol:ammonia:water 8:1:1 v/v. The strongest one indicated an apparent synergistic rooting effect with indol‐3yl‐acetic acid (IAA) regardless of the extraction method. These results indicate that water can extract from freeze ‐dried sample the similar rooting substances found in the centrifugal diffusates. The Rf 0–0.1 fraction consisted of at least four fractions and the strongest one did not move from the starting line on the chromatogram when isopropanol:ammonia:water 8:1:1 was used. This starting line fraction was extremely strong in rooting activity and its highest concentration resulted in 8.7 times as many roots as controls. More thain additive rooting effect between IAA and the fraction was found only at the highest concentration. The fraction was very soluble in water but insoluble in chloroform or ethyl ether and only stimulated rooting of mung bean cuttings when it was applied within 3 days after cuttings were made. It had no effect in lengthening roots. The starting line fraction was further found to have four root‐promoting subfractions at Rf 0.05, 0.35, 0.65, and 0.85 when it was chromatographed in 60 % isopropanol. Among these four, the subfractions at Rf 0.65 and 0.35 were strongly root promotive and displayed more than additive root promotion with IAA at the highest concentrations studied.
La biosynthèse de l'acide indolyl‐3‐acétique en liaison avec le métabolisme du tryptophol et de l'indolyl‐3‐acétaldéhyde chez Rhizobium
Authors: Rigaud Par Jean 
Published: April 2006

AbstractSeveral indolic compounds are formed when tryptophan or tryptamine is metabolized by Rhizobium. Among these are indole‐3‐acetaldehyde (IAAld), tryptophol (Tr‐ol), and indole‐3‐acetic acid (IAA). The metabolic relationship among the three compounds was investigated. The experiments were carried out either in the culture medium of growing Rhizobium cultures or in suspensions of washed bacterial cells. In neither case Tr‐ol would function as a precursor of IAA, but tryptophan‐2‐14G gave rise to the formation of both IAA and Tr‐ol. The ratio of IAA to Tr‐ol depended on the experimental conditions, shaking favoring the formation of IAA. Also IAAld gave rise to the formation of IAA and Tr‐ol when incubated with suspensions of washed cells. The ratio of the two compounds depended on experimental conditions such as pH value and shaking, the latter reducing the formation of Tr‐ol. These results cannot be explained by the assumption of a dismutation mechanism catalyzed by a single enzymatic unit. The operation of two enzyme systems, responsible for the reduction and the oxidation, respectively, of IAAld is suggested and discussed.