bluuebunny/crossref_metadata_2025 huggingface dataset:
Partial Synchronization of Cell Division in Suspension Cultures of Haplopappus gracilis
Authors: Eriksson Tage
Published: April 2006

Four different chemicals were tested in their ability to synchronize cell division in asynchronous cell cultures of Haplopappus gracilis.

Twentyfour‐hour treatments with 5‐amino uracil resulted in a peak in the mitotic index about 14–16 hours after the end of the treatment. The increase in the frequency of mitoses was about three times that of the control.

Hydroxyurea, at a concentration of 3 mM, gave after a treatment period of 12–24 hours an increase in the frequency of mitoses which appeared about 10 hours after the treatment. The mitotic index was about 35 per cent, which is 4 times that of the control.

5‐Fluorodeoxyuridine (FUdR) at a concentration of 2 × 10−7M gave a mitotic burst about 16 hours after treatment. At that time about 15 per cent of the cells were dividing which was about twice that of the control. The block was reversed with 4 × 10−5M thymidine.

Thymidine at a high concentration caused a reduction in the frequency of mitoses during the treatment. After 15 to 16 hours in a thymidine free medium a mitotic peak appeared with a doubling of the frequency of mitoses in treated cells.

Cytological studies showed that parlicularly hydroxyurea but also 5‐aminouracil and 5‐fluorodeoxyuridine produced gaps and fragments at the concentrations which gave cell synchronization.
Role of Auxin in Growth of Inhibitor‐treated Oat Coleoptile Tissue
Authors: Ordin L. , Garber M. J. , Skoe B. P. , Rollé G.
Published: April 2006

The role of auxin in the recovery of plant tissue from oxidant treatment was investigated. Treatment of oat coleoptile sections with concentrations of indoleacetic acid (IAA) or 2,4‐dichlorophenoxyacetic acid (2,4‐D) optimal for normal growth, following pretreatment with moderately inhibiting levels of peroxyacetyl nitrate (PAN) immediately accelerated recovery of growth rate. In some cases inhibition was also less at supraoptimal values of auxin. Treatment of ozonepretreated tissue with IAA or 2,4‐D enhanced inhibition at high levels of auxin and produced an optimal growth concentration level which was lower than for sections not given ozone pretreatment. Auxin treatment also reduced the degree of inhibition in fluoride and iodoacetamide‐pretreated sections. Mechanisms by which auxin‐induced recovery from inhibition may occur are discussed.
Acid Phosphatase in Dictyostelium discoideum
Authors: Gezelius Kerstin
Published: April 2006

An acid phosphatase has been studied at various stages of development of Dictyostelium discoideum. This enzyme has a pH optimum of 3.6 and catalyses the hydrolysis of both hexose phosphates and mononucleotides as well as that of p‐nitrophenyl phosphate. The enzyme specific activity increases 2–4 fold in vitro during differentiation, but the activity in vivo may be controlled through endproduct inhibition by orthophosphate, which accumulates in the cells during sorocarp formation. The predicted activity in vivo is highest in the middle of development, especially at the pre‐culmination stage.
Fe and Ca Uptake as Related to Root‐Sap and Stem‐Exudate Citrate in Soybeans
Authors: Brown J. C.
Published: April 2006

Two soybean varieties that differentially absorb and translocate iron were used to compare root‐sap citrate with stem‐exudate citrate as they are involved in the uptake of Fe and Ca. The status of Fe and PO4 in the prenutrient solution determined the citrate concentration in the root sap and the citrate translocated in the stem exudate. There was a parallel between the iron and the citrate translocated in the stem exudate, but this relationship did not appear to exist for the citrate and Fe concentrations in the root sap.

Iron stress (deficiency) promoted the accumulation of citrate in the root‐sap, but there was not a concomitant increase of citrate in the stem exudate. In iron‐deficient soybeans, phosphate stress also promoted the accumulation of citrate in the root sap, and here, stem‐exudate citrate and root‐sap citrate more nearly followed the same trends. The citrate pool in the root appears to result from a deficiency of iron and may not be directly involved in the absorption and translocation of iron from the growth medium. Increasing amounts of phosphate in the prenutrient decreased both the citrate and Fe in the root sap and stem exudate.

The factors controlling the uptake of Fe are rather specific and are not related to the uptake of radioactive Ca 45 in soybeans regardless of soybean variety, degree of iron stress, or citrate concentration in the root.
Protein Synthesis as a Requirement for Wound Xylem Differentiation
Authors: Fosket D. E. , Miksche J. P.
Published: April 2006

An increasing rate of protein synthesis was observed during the first 2 days after the isolation of 2 mm thick internodal stem slices of Coleus on a sucrose‐agar medium. This rise in the rate of protein synthesis preceeded the first visible signs of wound‐vessel member differentiation in the cultured stem slices. Irradiation of tissue slices with 4000 R of x‐rays at isolation reduced the numbers of wound‐vessel members differentiated after 7 days in culture by 51 per cent, and this level of x‐irradiation was observed to inhibit protein synthesis by the cultured stem slices. Treatment of the tissue slices with exogenous auxin (0.05 mg/1) after irradiation did not alter the degree of inhibition of xylem differentiation. Actinomycin D inhibited wound‐vessel member differentiation, but it had no effect on the endogenous growth of the cultured stem slices. Similarly, auxin at 0.05 mg/1 was without effect on the endogenous growth rate of the stem slices. Actinomycin D treatment was highly effective in inhibiting xylem differentiation if it was supplied to the tissues within the first 48 hours after isolation; actinomycin D treatment had no significant effect on xylem differentiation when it was given after the first 2 days of culture. Chloramphenicol (10−3M) inhibited both xylem differentiation and the endogenous growth of the cultured stem slices.
Action de la kinétine sur la croissance et la teneur en chlorophylles des racines
Authors: Pilet P. E. , Hofer R. M.
Published: April 2006

Lens roots form chlorophylls in well‐developed chloroplasts when they are cultivated in continuous light.

Chlorophyll accumulation was increased when kinetin (10−4M) was added for a short time (24 h) of treatment. For a long time (72 h), the increase of chlorophyll content was reduced when roots were cultivated in light and with kinetin.

When the roots were transferred from light to dark, chlorophyll content was decreased. This reduction was inhibited when roots were treated with kintin.

From these present result it was supposed that kinetin acts on the catabolism and the anabolism of chlorophyll. The necessity of kinetin for chloroplast from amyloplast maturation and differentiation was discussed.
Requirement of RNA for the Auxin‐induced Elongation of Oat Coleoptile
Authors: Masuda Yoshio , Wada Shunji
Published: April 2006

Using etiolated oat coleoptile segments the following results were obtained.

Actinomycin D pretreatment for one hour produced about 50 per cent inhibition of RNA synthesis (labeled uracil incorporation), but the elongation caused by IAA was not inhibited in the following 5 hours at least. Actinomycin D pretreatment for three hours produced about 75 per cent inhibition of RNA synthesis and almost complete inhibition of subsequent IAA‐induced elongation, which is accompanied by the inhibition of IAA‐induced increase in cell wall extensibility. The inhibiting effect of actinomycin D seemed to be reduced when IAA was given within a certain period.
Regeneration after Wilting, Growth and Yield of Wheat Plants, as Affected by Two Growth–Retarding Compounds
Authors: Plaut Z. , Halevy A. H.
Published: April 2006

The effect of spraying with 2–chloroethyltrimethylammonium chloride (CCC) and N‐dimethylaminosuccinamic acid (B‐995) on wheat plants exposed to various durations of wilting, was studied. The chemicals had little or no effect on dry matter production, grain yield, or water requirement of plants watered regularly or exposed to a short drought period causing one day of wilting. In plants exposed to two drought cycles of 5–6 wilting days each, a very pronounced increase in dry weight and grain production was found in plants treated with the two growth retardants. This effect was due to the increased ability of the treated plants to regenerate new shoots on rewatering after wilting. Longer drought periods of 10–12 wilting days, caused complete desiccation of both treated and untreated plants. The mode of action of the chemicals in increasing the drought tolerance of plants is discussed in relation to their effect on delaying the senescence of detached leaves.
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

Short 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

A 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

The 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

The 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

Spores 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

The 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

Mitochondria 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

Disks 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

The 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

From 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

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

A 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

Studies 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

Red 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

Effect 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

Gibberellic 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

Differences 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

A 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

In 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

A 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

The 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

Gibberellic 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

Plant 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.
DMPA and Avena Coleoptiles RNA Turn‐over
Authors: Briquet Michel V. , Decallonne Jacques R. , Lambert Raymond R. , Wiaux A. L.
Published: April 2006

Addition of α‐methoxy‐(3, 4‐dichlorophenyl) acetic acid (DMPA) at different concentrations in the culture medium of sub‐apical sections of Avena coleoptile results in an increased growth rate, which correspond to the quantitative measure of the increasing of ribosomal and soluble RNA turn‐over. The relative decrease in total RNA synthesis observed for the supraoptimal DMPA concentration of 1000 μg/ml appears to be due to the specifical retardation in the 4 S RNA turn‐over.
Duration of the Mitotic Cycle in Cell Cultures of Haplopappus gracilis
Authors: Eriksson Tage
Published: April 2006

The duration of the cell cycle and its component phases in cell cultures of Haplopappus gracilis was estimated by means of pulse labelling with tritiated thymidine and subsequent autoradiographic techniques.

The total duration of the mitotic cycle was found to be 22.0 hours. The average durations of the following component phases were: the synthetic period (S) 6.4 hours, the postsynthetic period (G2) 4.86 hours, prophase (P) 0.64 hours, metaphase (M) 0.40 hours, anaphase + early telophase (AT) 0.36 hours, the presynthetic period (G1) 9.34 hours.

The results indicate that G1 and G2 are the phases, which are most prolonged in populations of cultivated cells when compared to the same phases in root lip cells from the same species.
Effect of Preloading on Alanine Absorption by Wheat Roots
Authors: Fekete Maria , Cseh Edith , Böszörményi Z.
Published: April 2006

Studying the amino acid absorption by higher plants we observed a stimulation of 14C‐alanine absorption by wheat roots preloaded with inactive alanine. Within the limits of concentration examined the increase of stimulation is more likely to depend on the free alanine content of the roots than on the alanine concentration of the solutions used for pretreatment. The stimulation is retained even after incubating the pretreated roots in diluted CaSO4 solution before the uptake period. Besides the alanine only the glycine gave stimulation, while pretreatment with valine, arginine or aspartic acid gave an inhibition. (The aspartic acid is likely to cause a general rise in the permeability of cells.)

We suppose that the phenomenon of flow driven by counterflow is likely to serve as an explanation to the stimulatory preloading effect observed in the alanine absorption by wheat roots.
Changes in the Water Balance and Photosynthesis of Onion, Bean and Cotton Plants under Saline Conditions
Authors: Gale J. , Kohl H. C. , Hagan Robert M.
Published: April 2006

The osmotic concentration (osmotic potential) of onion leaf sap did not adjust to chloride salinity, and consequently water potential, turgor, stomatal aperture and transpiration were reduced. Although osmotic concentration of bean and cotton leaf sap did adjust to a saline root medium and turgor was no less in the salinized plants than in the controls, stomata of the salinized plants remained only partly open and transpiration was reduced.

Net photosynthesis of onion plants was reduced by salinity (this effect being much enhanced in a hot dry atmosphere) but it could be rapidly raised to the level of the controls by inducing elevated leaf turgor.

Stomatal closure was initially responsible for most of the ∼30 % reduction in photosynthesis of salinized beans. This was due to interference with CO2 diffusion and could be overcome by raising the CO2 concentration in the air. At a later stage of growth, salinity affected the light reaction of bean photosynthesis, and elevation of the air CO2 had little effect.

Closure of stomata of salinized cotton plants had only a relatively small effect on net photosynthesis. Light intensity and CO2 concentration experiments showed that salinity was reducing the photosynthesis of cotton leaves mainly by affecting the light reaction of photosynthesis.

It is concluded that chloride salinity does affect the water balance and rate of photosynthesis of plants and that the nature and degree of the effects will depend upon climatic conditions and may be very different between plant species and in the same species at different periods of growth.
Physiological Gradients in the Potato Tuber
Authors: Macklon A. E. S. , DeKock P. C.
Published: April 2006

The distribution of the major cations and anions, together with citric acid, malic acid and iron, has been studied in tubers of Solanum tuberosum cv. Golden Wonder, by analysis of longitudinal cores divided into 16 equal cylindrical sections.

In immature daughter tubers the constituents studied were evenly distributed along the tuber, but in mature tubers a considerable polarity had developed. The concentrations of potassium, phosphorus and citric acid each rose from the heel to the rose end of the tuber. Iron showed a gradient in the opposite direction. These gradients were maintained in sprouting tubers, and although after 25 days the levels of these constituents were reduced, the patterns of distribution were unchanged. In the exhausted mother tubers all these constituents were much depleted and only potassium exhibited any pattern of polar distribution. Malic acid was barely detectable at any stage, and calcium, sodium, magnesium, chloride, sulphate and nitrate were always at low levels and showed no polarity of distribution.

At each developmental stage potassium was correlated with the difference in electrical potential measured between cells at points across the tuber. A close correlation was apparent between potassium and citric acid content in young, mature and sprouting tubers. In all stages a considerable discrepancy existed between total anions and total cations and this was attributed to the presence of organic acids other than citric acid.
Mechanism of Action of Abscission Accelerators
Authors: Abeles F. B.
Published: April 2006

Abscission zone explants of Gossypium hirsutum L., Cassia fistula L., and Coleus blumei Benth. were used to investigate correlations between endogenous rates of ethylene evolution and time of abscission. Additions of 0.1 nl/ml ethylene to the explants markedly accelerated abscission; continuous aeration of the explants, to prevent accumulation of small amounts of endogenously produced ethylene, inhibited abscission compared with that of sealed controls. Substances that stimulated abscission simultaneously accelerated ethylene evolution on all three species and at any position of application.

The positional effects of auxin are explained as being due to differences in transport in the explant. Thus, distally applied auxin inhibits abscission, regardless of the accelerated rate of ethylene evolution, by being rapidly transported to the abscission zone. Auxin applied proximally stimulates abscission because it is unable to move as rapidly to the abscission zone and the ethylene effect becomes dominant.

Ethylene was found to be most effective on aged tissues, and it is concluded that abscission rates are determined by an increase in sensitivity of the tissue to the ethylene that is already being produced.
Isoenzyme Polymorphism in Flowering Plants I. Diffusion of Enzymes Out of Intact Pollen Grains
Authors: Mäkinen Yrjö , Brewbaker James L.
Published: April 2006

Esterases, leucine aminopeptidases, catalases, amylases and acid phosphatases diffuse out of intact and ungerminated pollen grains of Oenothera organensis, whether suspended in 1 % sodium chloride or in pollen medium. A total of 15 esterase isozymes are recorded; 5 of them appear within 5 minutes, 8 within 30 minutes, 9 within 2 hours, and 13 within 19 hours. Pollen grains suspended for 19 hours gave much stronger isozyme bands than macerated pollen grains. However, one esterase hand was consistently missing from the 19 hour suspensions, although present in all others.

It is suggested as a working hypothesis that the early growth of pollen tubes and possibly even germination of pollen grains may be influenced by the metabolic products of pistillate tissues caused by the diffused pollen enzymes, and that inactivation of these enzymes by stigmatic or stylar components could lead to incompatibility reactions.
The Light Requirement for Different Steps in the Development of Chloroplasts in Excised Wheat Roots
Authors: Björn L. O.
Published: April 2006

For the formation of chloroplasts in excised wheat roots blue light is necessary, but red light enhances the blue light effect. Intensity‐response relationships and action spectra have been determined for the specific blue light effect as well as for the effect of red light when given before or after blue light.

The longest wave length giving a blue light effect is about 500 nm. The spectrum shows a peak at about 450 nm, and a considerable effect extends down to 368 nm, the shortest wave length tested. The photoreceptor mechanism for the “blue reaction” is thought to be related to that of certain phototropisms and chloroplast movements, and to that involved in carotenoid synthesis in certain fungi. The active pigment is thought to be either a carotenoid or a flavoprotein, probably the latter.

The effect of red light shows similar action spectra whether the red light is given before or after the blue, and they are consistent with protochlorophyll absorption. However, much less light is needed to produce a detectable response when the red light is given before the blue light than after. Because of the similarity of the spectra phytochrome may also be involved in the response to red light when given before blue. Far‐red reversal has not been tested. The results are discussed in relation to the development of chloroplasts in leaves.
Action inhibitrice de l'acide 3‐indolyl‐acétique sur la croissance de quelques Basidiomycètes mycorhizateurs
Authors: Fortin J. André
Published: April 2006

La croissance en milieu liquide de quelques champignons mycorhizateurs a étéétudiée en présence d'acide 3‐indlolyl‐acétique (AIA). Les champignons suivants ont été utilisés: Amanita muscaria (L. ex Fr.) Quél., A. rubscens (Pers. ex Fr.) Quél., Suillus granulatus (L. ex Fr.) O. Kuntze et S. variegatus (Sw. ex Fr.) O. Kuntze. Tous ont été inhibés, à des degrés divers, par l'AlA à la concentration do 1.75 mg/l.

Soumis à diverses concentrations d'AIA, S. variegatus a montré une croissancc légèrement accrue au voisinage de 0.2 mg/l de cette substance. Cependant, pour des concentrations supérieures à celle‐ci, l'inhibition de la croissancc a été proportion‐nelle à la concentration en AIA; elle a été de 50 pour‐cent en présence de 2.0 mg/l d'AIA.
Gibberellin Effect on Tryptophan Metabolism, Auxin Destruction, and Abscission in Coleus
Authors: Valdovinos Jack G. , Ernest Leland C. , Perley James E.
Published: April 2006

Application of gibberellic acid (GA) to the apical region of the stem enhances 14CO2 release from tryptophan‐l‐14C in cell free preparations of the apical region. Although GA when applied to the apical region markedly accelerates abscission rates of debladed petioles at the 4th node, the enhancement effect on tryptophan metabolism appears to be restricted to the apical bud region. The increased levels of diffusible auxin in Coleus stems, observed earlier by Muir and Valdovinos (1965), appear to be due to the GA effect on auxin precursor conversion rather than to an altered rate of auxin destruction. GA pre‐treatment does not significantly alter destruction rates of auxin in the stem tissue. This is demonstrated by the release of 14CO2 from IAA‐1‐14C by sections of internode tissue.

While a multiple deblading pattern retards abscission of debladed petioles considerably, application of GA to debladed petioles at the basal region of the stem restores the normal rates of abscission at debladed distal nodes. No significant change in the abscission rates at treated nodes is observed. The GA effect on abscission at distal nodes is attributed to the effect of the growth substance on auxin precursor conversion in the apical region. In these experiments, as in the case of plants treated in the apical region with GA, auxin destruction rates in the stem are not altered significantly.
Distribution of Intercellular Material in the Apical Part of Pea Seedlings
Authors: Sorokin Helen P.
Published: April 2006

The sections from the upper part of the third internode, counted from the seed, in etiolated pea seedlings are studied for the distribution of two types of Intercellular spaces: the transparent and the dark. The transparent spaces represent the result of the water logging of passages originally water‐lined, while the dark spaces are lined with a lipid‐containing substance which may be impregnated with melted paraffin and which forms a ramifying network within the tissue. The intercellular material of the dark spaces has the appearance of a tube, since it concentrically lines the intercellular space, leaving a lumen for air or gas. It is a plastic, isotropic subslance which may be cut transversely and identified in successive sections of the inlernode as belonging to the same continuous material from the intercellular space. The dark and the transparent spaces have a distinct pattern of distribution in the growing internode, and the relative quantity of dark spaces present at different levels of the internode may be measured. The dark spaces predominate in those parts of the stem with a greater potential for growth, while the transparent spaces are located in the regions where growth has ceased or subsided. Since the paraffin is infiltrated instantaneously throughout the network of dark intercellular spaces, it is possible that these may represent a channel for the translocation of substances.
Nutritional Requirements for Polyploid Mitoses in Cultured Pea Root Segments
Authors: Matthysse Ann G. , Torrey John G.
Published: April 2006

Diploid and polyploid mitoses could be stimulated in excised segments of the mature region of pea roots grown on a sterile culture medium. Diploid mitoses were observed in segments cultured on water alone for 72 hours. Their frequency was increased by the presence of salts, sucrose, vitamins, and any two or all three of the following: an amino mixture, auxins, and kinetin.

Polyploid mitoses were observed 72 hours after the beginning of the culture period in segments cultured on salts, sucrose, vitamins, auxins, and kinetin. Polyploid mitoses required the presence of auxins and kinetin in the culture medium. Their frequency was not affected by the presence of a reduced nitrogen source. Light treatments had no effect on the frequency of diploid or polyploid mitoses.

Diploid mitoses were first observed about 24 hours after the beginning of the culture and their frequency increased thereafter. Experiments with colchicine showed that diploid cells were entering mitosis for the first time as late as 60 hours after the beginning of the culture.

Polyploid mitoses showed a long lag time when compared with diploid mitoses. They began at about 60 hours and their frequency increased thereafter. Experiments with colchicine showed that polyploid cells were entering mitosis for the first time as late as 84 hours after the beginning of the culture.

The presence of kinetin in the medium was not required during the first 24 hours in culture for the appearance of polyploid mitoses at 74 hours. However, the presence of kinetin was required after 24 hours. Auxin was required at some time during the first 24 hours of the culture and its continuous presence may be required for the stimulation of polyploid mitoses.