bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Intermittent and Continuous Light on Chlorophyll Formation in Etiolated Plants
Authors: Akoyunoglou G. , Argyroudi‐Akoyunoglou J. H. , Michel‐Wolwertz M. R. , Sironval C. 
Published: April 2006

AbstractShort impulses of white light induce continuous synthesis of chlorophyll a and b in etiolated barley leaves. No lag phase is observed, and the rate of chlorophyll a accumulation is much higher than that of chlorophyll b, so that the a/b ratio is very high (12 to 20). The chlorophyll accumulation reaches a plateau at about 70 flashes after which the rate of their formation decreases appreciably.When the etiolated plants, after exposure to about 80 to 100 flashes, are transferred to continuous light, one can observe that the rate of formation of chlorophyll a and b increases during the first hour, and after that becomes still more rapid. At the same time the a/b ratio falls and it reaches a value of about 3 normally found in green leaves.
Sterile Germination Requirements of Seeds of Some Water Plants
Authors: Forsberg Curt 
Published: April 2006

AbstractA sterile germination study with seeds of some common phanerogamic water plants showed almost 100 per cent germination for seeds of Alisma plantago–aquatica, Baldellia ranunculoides and Nymphaea alba. Seeds of Potamogeton lucens could be germinated to about 40 per cent, seeds of Polygonum amphibium germinated sporadically while those of Cladium mariscus could not be germinated at all.Freshly harvested seeds of Alisma and Baldellia showed an ability to germinate at both 20°C and 35°C. A stratification period of one month at +4°C gave germination of all species tested, with the exception of Cladium. Potamogeton germinated in light only, the other species both in light and darkness. Treatment times for surface sterilization in disinfectants are given.
A Comparison between Geotropism and Geoelectric Effect in Pisum sativum and Its Mutant ageotropum
Authors: Ekelund Rolf , Hemberg Torsten 
Published: April 2006

AbstractThe auxin concentration in roots of Pisum sativum ageotropum was examined by three indirect methods:

Supply of auxin before geotropic stimulation;
Lateral placing of the root tip;
Inhibiting the auxin transport in half of the root.

All the results indicated supraoptimal auxin concentration.When decapitated ageotropum roots were supplied with 1.5 mm long tips from normal Pisum roots their geotropic reactivity was almost restored.The geoelectric potential of stems of Pisum sativum and its mutant ageotropum was measured. In ageotropum stems the geoelectric potential was less and the geotropic reaction appeared later than in the normal stems.
The Nature of the pH EfFect on the Uptake of Rubidium by Excised Barley Roots
Authors: Waisel Yoav , Neumann Ruth , Eshel Yael 
Published: April 2006

AbstractThe specific effects of pH on the accumulation mechanism of Rb+ by excised barley roots were investigated.Exposure of roots to solutions of a wide range of pH values did not result in any noticeable damage. It is therefore suggested that even pH 3.5 is within the physiological range of pH for barley roots.It is assumed that the inhibitory effect of pH on Rb+ accumulation is due to competition of H ions on binding sites of the temperature dependent metabolic accumulation mechanism. When this mechanism is saturated with Rb ions, no inhibition of H ions occurs, even at pH 3.5.Temperature coefficients provide hints that the inhibitory effects of Na and H ions on Rb+ accumulation are similar.
Light Dependence of Chloroplast Replication and Starch Metabolism in the Moss Polytrichum commune
Authors: Hahn Lamont W. , Miller John H. 
Published: April 2006

AbstractSpores of Polytrichum conwtuine were grown on a mineral salt solution with or without sucrose and exposed to continuous white light, continuous darkness, red light and/or far‐red light. With sucrose, germination and filament growth occurred in all conditions, Without sucrose, germination and filament growth occurred only in light. Two phytochrome mediated responses of the chloroplasts were demonstrated. Chloroplast replication occurred in continuous white light and red light of 15 min/6 hours. In continuous darkness and in far red light of 15 min/6 hours, the size of the chloroplasts increased; but no replication occurred. Both the chloroplast replication and chloroplast size were red, far‐red light reversible. When changed from one continuous light environment to another, a lag period occurred before the chloroplasts responded to the new environment. Electron micrographs of sections and in vivo staining of the chloroplasts with iodine solution demonstrated that the change in size of the chloroplasts was at least partially due to the synthesis and degradation of starch.
Microscopical Investigation of the Efifect of Helminthosporol on Rice Seedlings
Authors: Okuda Mitsuro , Kato Juro , Tamura Saburo 
Published: April 2006

AbstractThe elongation of the second leaf sheaths of rice seedlings was promoted strongly by helminthosporol as well as by gibberellic acid. A greater dosage of helminthosporol was required in order to induce the same amount of elongation.Cells of treated plants were somewhat longer than those of controls. The elongation of the second leaf sheath was caused mainly by an increase in cell number.Both helminthosporol and gibberellic acid promoted the elongation of cells in the basal portion of the second leaf sheath.
Enhancement of Oxidation and Phosphorylation of Maize Scutellum Mitochondria by Physiological Concentration of Indoleacetic Acid
Authors: Mcdaniel Robert G. , Sarkissian Igor 
Published: April 2006

AbstractMitochondria isolated from inbred and hybrid maize scutella were found to exhibil enhancd oxidative and phosphorylative activity in many cases when treated with physiological concentrations of IAA. It was found that the genotype being tested the substrate utilized, and the concentration of IAA applied had significant effects on the degree of enhancement or inhibition observed in each case. These results suggest that IAA is related in some manner to theactivity of the respiratory enzymes of the mitochondria.
Aging and the Development of Enhanced Respiration in Potato Tuber Tissue
Authors: Lee S. G. , Chasson R. M. 
Published: April 2006

AbstractDisks of potato tissue were aged by two separate methods. The resulting enhaiicetl respirations differed both qualitatively and quantitativety. It is suggested that the diverse results previously reported indicating changes in the terminal oxidative steps and/or in the relative contributions by competing metabolic pathways to the total respiration reflect variations in the methods employed to age the tissues. The nature of the stimulated respiration is discussed in terms of removal or retention of metabolites within the tissue during aging.
Light‐Dark Transients in Levels of Intermediate Compounds during Photosynthesis in Air‐Adapted Chlorella
Authors: Pedersen T. A. , Kirk Martha , Bassham J. A. 
Published: April 2006

AbstractThe labeling of intermediate compounds and photosynthetic cofactors during photosynthesis and periods of darkness by Chlorella pyrenoidosa in the presence of 32P‐labeled phosphate and 14CO2 have heen investigated. Algae adapted to photosynthesis in air were used, and the level of carbon dioxide was maintained at approximately 0.04 % and at constant specific radioactivity during the course of the experiments.The transient changes which occur in the levels of labeled fructose‐1,6‐diphosphate and in sedoheptulose‐1,7‐diphosphate, and in the corresponding monophosphates when the light is turned off suggest a light activation of the diphosphatase enzymes which decays after about 2 minutes of darkness. It is suggested that a light‐dark switch in enzymic activities permits photosynthesis and glycolysis to occur in light and dark respectively with the same enzymic apparatus.The greatly diminished rate of disappearanec of the carboxylation substrate, ribulose‐1,5‐diphosphate, after about 2 minutes suggests that there is also a light activation of the carboxylation reaction in vivo. Large transient changes in the level of pyrophosphate between light and dark indicate that there may be an unstable cofactor which decomposes to give pyrophosphate during or alter killing of the algal cells. The possibility that this cofactor is involved in an activation of Carbon dioxide for the carboxylation reaction in vivo is suggested.Light‐dark transient changes in labeling of other compounds of the photosynthetic carbon reduction cycle and related compounds were determined, and possible significance of these changes is discussed.(PDF DAMAGED)
The Uptake of Free CO2 and HCO3‐ during Photosynthesis of Plankton Algae with Special Reference to the Coccolithophorid Coccolithus huxleyi
Authors: Nielsen E. Steemann 
Published: April 2006

AbstractFrom a re‐evaluation of experiments with the coccolithophorid Coccolithus hurleyi made by Paasche (1964), curves are presented showing the rate of photosynthesis as a function of the concentration of both free CO2 and bicarbonate CO2. It is shown that photosynthesis in a naked clone is due only to the uptake of free CO2.The problem concerning the high concentration of free CO2 necessary for photosynthesis in Coccolithus huxleyi is discussed. It is shown that it is not due to lack of the enzyme carbonic anhydrase.Hence it is probable that the formation of coccoliths is the mechanism by which, in Coccolithus, the utilization of HCO3‐ ions in photosynthesis becomes possible. The OH‐ ions produced during photosynthesis (+Ca2+ taken up together with the HCO3‐ ions) are thus neutralized. This situation is different from other aquatics utilizing HCO3‐ in photosynthesis. Here the OH‐ ions are neutralized via an ion exchange of Ca2+ with H+ in the surrounding medium.
The Effects of Gibberellic Acid and Scarification on the Seed Dormancy and Germination in Luzula spicata
Authors: Amen Ralph D. 
Published: April 2006

Abstract Luzula spicata L. seeds are completely dormant at maturity. A germination inhibitor is present at the micropylar end. Normally, the only effective means of eliciting germination is a precise scarification of the micropylar end which inactivates the inhibitor. Exogenous application of gibberellic acid, kinetin, KNO3, and thiourea have no affect on the dormancy of unscarified seeds. Scarification of the hilar end of the seed does not elicit germination, but when gibberellic acid is applied to the hilar scarified seeds moderate germination results. Presumably, these seeds are dormant due to a deficit of endogenous gibberellin; a condition which can be overcome by the application of gibberellic acid to seeds scarified at a site in itself ineffective in producing germination. Apparently the gibberellic acid serves to initiate amylase activity in the endosperm, overcoming the inhibitor block. Luzula spicata seed dormancy is apparently unique in that a germination inhibitor is operative in conjunction with the commonly recognized gibberellin‐amylase mechanism.
Regulation of Mitosis in Living Cells. I. Mitosis under Controlled Conditions
Authors: Jackson Wm. T. 
Published: April 2006

AbstractA quantitative method has been devised to study mitosis in vitro by phase contrast and polarization microscopy. Mitosis in cell‐wall‐free endosperm cells of Haemanthus kathrinar Baker (the African blood lily) has been divided into 18 arbitrary stages or events. The time course for the various stapes, as well as the percentage of cells that proceed from one stage to another during a four hour observation period, are presented. Cells that were in prophase when selected for study proceeded from nuclear membrane breakdown to melaphase in 60 minutes and remained in melaphase for 30 minutes. Only 13 minutes was required to proceed from onset of anaphase to mid‐anaphasc. Mid‐anaphase provides a clear and precise baseline for determining the time required for succeeding stages to appear. The cell plate made its appearance 40 minutes after mid‐anaphase and was completely formed 20 minutes later. The nuclear membranes also became evident at this latter time and nucleoli were visible 30 minutes later. Thus, the average time for a cell observed initially in prophase to proceed from nuclear membrane breakdown to formation of two daughter cells was just over three hours. A high percentage of cells that were in late prophase or later stages of mitosis at the time of initial observation completed mitosis during the observation period. The effect of the length of time a cell is subjected to experimental conditions upon its subsequent behaviour is assessed. These results form the basis for future studies of the effects of chemicals, particularly herbicides, upon cells in mitosis as observed in vitro by phase contrast and polarization microscopy.
Effects of Calcium Ion and the Protective Action on Survival and Growth Inhihition of Pollen
Authors: Kwack Beyoung H. , Kim In‐Hwan 
Published: April 2006

AbstractStudies were conducted on the protective action of Ca against growth inhibition and death of pollen from Crinum asiaticum and Catharanthus roseus. Ca ions not only promoted pollen germination and pollen tube growth, but also were antagonistic to pollen injuries induced by various chemical and physical treatments. Most of the chemicals used seemed to act as osmotic inhibitors. Among the chemical agents tested, DNP inhibited pollen germination more strikingly with Ca than without it, whereas pollen tube growth was enhanced. Another metabolic inhibitor, low temperature, showed a similar effect on pollen germination. Insignificant or no protective action of Ca was observed when IAA, TIBA and coumarin, were applied.Large populations of pollen when grown in cultural media witbout Ca showed a partial protective action.The protective action of Ca in pollen growth against various inhibitors required other cations such as Mg and K ions. The promoting of pollen growth by Ca also required tbese otber cations.The protective action of Ca is considered to be based on its binding in tbe pollen cell walls, particularly in the pectic regions. This gives rise to a decreased permeability and increased structural rigidity against tbe chemical and physical inhibitors.
Enhancement of Drought Tolerance hy Applied Thiols
Authors: Paricha P. C. , Levitt J. 
Published: April 2006

AbstractRed cabbage sections treated with 0.5 M sucrose showed a slight increase in tolerance on exposure to drought. This was so small that it may simply represent a removal of injury due to excess turgor in distilled water. Drought tolerance was markedly increased by mercaptoethanol (ME), but not by glutathione. Sulfhydryl reagents (PCMB and NEM) were unable to enhance drought tolerance unless replaced by ME during rehydration.
Effect of Auxin and Gibberellin on Sporulation in Yeast
Authors: Kamisaka Seiichiro , Yanagishima Naohiko , Masuda Yoshio 
Published: April 2006

AbstractEffect of auxin and gibberellic acid on sporulation of a yeast, Saccharomyces ellipsoideus, was studied. When added to the sporulation media, gibberellic acid promoted sporulation. The sporulation rate was higher in the medium SGV with vitamins than in the vitamin‐free SG, but the effect of gibberellic acid was more pronounced in the latter. Auxin (IAA, 2,4‐D, and NAA) inhibited sporulation in SGV, but promoted it in SG. This sporulation‐promoting effect of IAA was reversed by an antiauxin, 2,4,6‐T.Preculturing in the presence of added IAA increased sporulation. Added to the preculture medium, gibberellic acid alone showed little effect on sporulation, but in combination with IAA it enhanced sporulation conspicuously.IAA and gibberellic acid were effective in sporulation promotion only when added before the nuclear enlargement occurred in sporulation culture.
Gibberellin‐induced Yeast Sporulation in Relation to RNA and Protein Metabolism
Authors: Kamisaka Seiichiro , Masuda Yoshio , Yanagishima Naohiko 
Published: April 2006

AbstractGibberellic acid (GA) promoted sporulation in yeast when added to the sporulation medium. When added together with GA, metabolic inhibitors of RNA synthesis such as 8‐azaguanine, 2‐thiouracil, and actinomycin D suppressed selectively the promoting effect of GA on sporulation. The effect of 8‐azaguanine and 2‐thiouracil was alleviated by simultaneous addition of guanine and uracil, respectively.The promoting effect of GA on sporulation was also suppressed by inhibitors of protein synthesis such as ethionine, chloramphenicol, and puromycin. Methionine eliminated the inhibitory effect of ethionine on the GA action.
Apparent Reassimilation of Respiratory Carbon Dioxide by Different Plant Species
Authors: El‐Sharkawy M. A. , Loomis R. S. , Williams W. A. 
Published: April 2006

AbstractDifferences among species in respiration rates in CO2‐free air, in light and dark, were studied using the standard leaf chamber technique and the infrared carbon dioxide analyzer. Photosynthesis, transpiration and respiration were measured. In all species studied, rates of respiration were considerably higher in dark than in light. This effect was assumed to be due to reassimilation of the respiratory CO2. A resistance analogy model was derived to account for the apparent differences in internal recycling of CO2 among species; the differences were correlated with differences in maximum photosynthetic rates in normal air and optimal conditions (P310) and with internal resistances to CO2 diffusion (rk). Species with high P310 and low rk appear to reassimilate all the endogenous CO2, whereas other species with lower P310 and higher rk appear to reassimilate only a part of their respiratory CO2.Experiments with the photosynthetic inhibitor, 3‐(3,4‐dichlorophcnyl)‐l,l‐dimethyl urea (DCMU), indicated that species with zero respiration in CO2‐free air and light release respiratory CO2 when photosynthesis is inhibited. It is concluded that the CO2 released in the presence of DCMU represents respiratory CO2 which recycles to photosynthesis under normal conditions.
Substances Isolated from Woody Cuttings of Salix atrocinerea and Their Growth Properties
Authors: Vieitez E. , Seoane E. , Gesto D. V. , Mato M. C. , Vazquez A. , Carnicer A. , Peña J. 
Published: April 2006

AbstractA study of the cuttings of Salix atrocinerea Brot. was made by extraction with methanol, paper chromatography and Avena coleoptile straight growth test. In the acidic fraction, indole‐3‐acetic acid (IAA; about 15 μg per kg fresh weight) and p‐hydroxybenzoic acid (PHB; about 850 μg per kg fresh weight) were isolated and identified. The growth activity of the different zones is explained by their content of these two compounds. The watersoluble residue, insoluble in ether, showed growth Stimulating activity, which probably is due to a bound auxin (IAA‐sugar); alkaline breakdown of this aqueous residue, giving PHB, vanillic and p‐coumaric acids, suggests the presence (in the cuttings of Salix atrocinerea) of glycosides with aglycones similar to rhamnacine and scutellareine.
Studies onOrobanche hederaePhysiology: Pigments and CO2Fixation
Authors: Baccarini A. , Melandri B. A. 
Published: April 2006

AbstractIn order to investigate some aspects ofOrobanche hederaephysiology in relation to its parasitism, the pigment composition and the14CO2incorporation, both in light and in dark, were studied.By means of various chromatographic techniques, it was shown that chlorophyll is probably quite absent and that the carotenoids are very largely distrihuted and consist almost exclusively of xanthophylls.Flavochrome, flavoxanthin, and a pigment resembling neoxanthin were found to be the major components; lutein‐5,6‐epoxide, taraxanthin, and traces of β‐carotene and α‐carotene‐5,6‐epoxide were also present.CO2incorporation is completely of heterotrophic type, being in no way stimulated by the light; the major radioactivity was detected in the fractions containing amino acids and organic acids.
Morphogenesis in Relation to Chromosomal Constitution in Long‐term Plant Tissue Cultures
Authors: Torrey John G. 
Published: April 2006

AbstractA number of strains of callus tissues derived from 1‐mm root tips of the garden pea, Pisum sativum L., cultivated on a complex medium containing yeast extract and 2, 4‐D for eight years, were tested periodically for their capacity to initiate roots. Chromosomal cytological analyses accompanied each test. It was found that during the prolonged period of subculture there was a progressive loss of organ‐forming Capacity in all tissue strains. At the outset all callus tissues could be stimulated to form normal diploid roots. After several years of continuous subculture, some callus tissues formed normal tetraploid roots. Still later, these callus tissues lost completely the capacity to initiate roots. This loss was paralleled by increasing abnormalities in the chromosomal constitution, including higher chromosome numbers and greater frequency of aneuploidy.Early in subculture normal diploid and tetraploid divisions were present in the callus tissues. Later, higher polyploids at 8n and 16n were more frequent, as well as aneuploids around these numbers. Some tissue strains after prolonged cultivation showed a wide range of chromosome numbers at the higher ploidy levels but completely lacked diploid divisions. It is suggested that the loss in organ‐forming capacity is correlated with the increase in abnormality of chromosomal constitution. Differentiation of certain characteristic cell types was unaffected by these changes.
Auxin Content and Auxin Catabolism in Relation to the Growth Polarity
Authors: Pilet P. E. 
Published: April 2006

AbstractThe auxin level in the root fragments of carrot cultivated in vitro is inversely related to the auxin‐oxidase activity. In the morphological basal region, auxin catabolism is low and, in consequence, auxin content is high. This accumulation of the endogenous auxin leads to the induction of callus. In such new tissues, IAA‐oxidase activity is also very low and, similarly, the auxin content is high: thus, cells can growth rapidly. Consequently the growth polarity is directly related to the auxin catabolism.
Effect of Gibberellic Acid on Dwarf and Normal Pea Plants
Authors: Tanimoto Eiichi , Yanagishima Naohiko , Masuda Yoshio 
Published: April 2006

AbstractGibberellic acid at concentrations between 10 and 100 mg/1 greatly stimulated the elongation growth of intact dwarf pea plant but showed little or no effect on that of Alaska pea. It showed no effect on the elongation growth of excised stem segments of either dwarf or normal pea when given alone. Indole‐3‐acetic acid stimulated the elongation of excised segments of both varieties. Gibberellic acid synergistically enhanced the indole‐3‐acetic acid‐induced elongation of excised segments. Tryptophan also stimulated the elongation of these segments. Gibberellic acid showed a synergistic effect on the tryptophan‐induced elongation, as on the indole‐3‐acetic acidinduced one. Gibberellic acid reduced the lag period of tryptophan‐induced elongation, suggesting that gibberellic acid promotes the conversion of tryptophan to auxin.
Physiology of Morphactins: Effect on Gravi‐ and Photo‐response
Authors: Khan A. A. 
Published: April 2006

AbstractPlant roots and shoots respond to gravity and light source in a definite way. Thus, there are typical geotropic and phototropic responses for roots and shoots. When seedlings were grown in presence of morphactins, IT 3233 or IT 3456, on a vertical or a horizontal plane, the roots and shoots lost the capacity to respond to gravity or to unilateral light source. This was true for both monocots and dicots. This suggests that basic mechanism (s) of the two tropic responses are the same in the roots and shoots of the two plant groups. The site(s) of action of morphactins is unknown. The reaction (s) controlling geotropism and phototropism may be closely related as morphactins affected both geotropic and phototropic response of the same organ. Indoleacetic acid and gibberellic acid per se did not modify the effect of morphaclins on geotropism. Growth retardation effect of morphactins appears to be controlled by another mechanism.