bluuebunny/crossref_metadata_2025_split huggingface dataset:
DMPA and Avena Coleoptiles RNA Turn‐over
Authors: Briquet Michel V. , Decallonne Jacques R. , Lambert Raymond R. , Wiaux A. L. 
Published: April 2006

AbstractAddition 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

AbstractThe 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

AbstractStudying 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

AbstractThe 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

AbstractThe 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

AbstractAbscission 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

AbstractEsterases, 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

AbstractFor 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

RésuméLa 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

AbstractApplication 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

AbstractThe 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

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

AbstractThe effect of growth retarding compounds, (2‐chloroethyl)trimethylammonium chloride (CCC), 2‐isopropyl‐4‐dimethylamino‐5‐methylphenyl‐1‐piperidinecarboxylate methyl chloride (AMU‐1618), tributyl‐2,4‐dichlorobenzylphosphonium chloride (Phosfon D) and N‐dimethylamino succinamic acid (B‐995) on α‐amylase production in germinating barley seed was studied. Seeds were germinated in growth retardants in presence and absence of gibberellic acid (GA3). CCC, AMO‐1618 and Phosfon D inhibitedα‐amylase production in germinating seed and the effect was reversed by GA3 Phosfon D and AMO‐1618 were stronger inhibitors of α‐amylase production than CCC. CCC was by far the strongest inhibitor of all the other analogs tested. B‐995 was comparatively only slightly inhibitory.The results reported here, when viewed in light of the results of other workers, provide good evidence that CCC, AMO‐1618 and Phosfon D inhibit α‐amylase production by inhibiting the synthesis of gibberellin or gibberellin‐like hormone(s) during germination of barley seed. Consistent with other reports, B‐995 possibly acts by other mechanism (s).
Influence of the Embryonic Axis on Protein Hydrolysis in Cotyledons of Cucurbita maxima
Authors: Wiley Lorraine , Ashton Floyd M. 
Published: April 2006

AbstractFour‐day time course studies of the hydrolysis of cotyledonal storage protein were conducted on intact seeds, seed cotyledons detached from their embryonic axes and on detached cotyledon pairs germinated in the presence of three excised embryonic axes of Cucurbita maxima Duch., cv. Chicago Worted Hubbard. Detached cotyledons germinated alone showed little hydrolysis of the storage protein. However, the amount of protein hydrolysis of the detached cotyledon pairs germinated in the presence of three excised embryonic axes was comparable to the amount hydrolyzed in the cotyledons of intact germinating seeds. Visual growth differences among these treatments were also evident. The size and yellow color intensity of the fourth day treatments were shown to increase in the following order: detached cotyledon pairs alone, intact seedlings, detached cotyledon pairs in the presence of three excised axes. The growth of the hypocotyl and radical was also modified by removal of the cotyledons. These findings suggest that storage protein degradation and cotyledonal growth are controled by the axis. They also indicate that the cotyledons have some influence on the growth of the axes.Time‐course studies were made on the hydrolysis of storage protein in the cotyledons of squash and on the distribution of the hydrolytic products during the germination of light‐ and dark‐grown plants. The storage protein was not hydrolyzed during the first 24 hours. It was hydrolyzed at a uniform rate from 1 to 5 days and at a slightly decreased rate from 5 to 7 days. Most of the hydrolytic products were transported to the axial tissue.Proteinase activity in the cotyledons rapidly increased during germination to a maximum level at 2 to 3 days. This was followed by a decline to about the initial value after 7 days.
Effects of Supraoptimal Temperatures on Merulius lacrymans
Authors: Langvad Finn , Goksøyr Jostein 
Published: April 2006

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

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

AbstractThe photosynthates from leaves from extension shoots may be used either for new growth of the shoot itself, or for growth in other parts of the tree. An attempt has been made to elucidate this problem by determining the content of 14C in long shoots to which 14CO2 was applied either through fully developed leaves at the base, or through very young leaves at the apex.In the case of 14C application at the base, 80 per cent or more of the 14C initially taken up disappears from the shoot, and only a very minor part is translocated upwards in the shoot. When the leaves at the apex are exposed, on the other hand, 80 per cent of the 14C absorbed is retained in the leaves and shoot components treated as long as there is still considerable terminal growth taking place, although a small percentage is deposited in the lower parts of the shoot. At the same time, a much higher proportion is incorporated into methanol‐insoluble components. As terminal growth decreases, a larger proportion of the 14C activity of the apex leaves also disappears from the shoot.The distribution of activity between the sorbitol, sucrose, glucose and fructose fractions was not significantly different in young and in fully developed leaves. The 14C labelling in the sugar fraction was highest for sorbitol, then sucrose, but decreases with time compared to glucose and fructose.
Environmental and Genetic Control of Dormancy in Picea abies
Authors: Worrall John , Mergen François 
Published: April 2006

AbstractThe effects of temperature, photoperiod and chilling on the leafing‐out of Norway spruce, Picea abies (L.) Karst. were studied. High temperature promotes breakage of post‐dormancy, long photoperiods having no such effect. Photoperiod and chilling cause the breakage of true dormancy. However, under field conditions, photoperiod will have no effect on leafing‐out date in the spring.By use of clonal material it was possible to show substantial genetic differences between individuals in response to temperature and photoperiod. When the effect of clones was accounted for, treatments could be compared more precisely. Differences between clones were apparent in heat‐sum required for leafing‐out, in rapidity of response to favorable post chilling conditions, and in chilling requirement This latter quantity was given a new definition, applicable when both chilling and post chilling temperatures are controlled and specified. This is that period beyond which a further 10 days of chilling accelerates leafing‐out by less than one day, i.e. the point at which the slope of the line relating days till leafing‐out to chilling period, is equal to minus 0.10.Differences in leafing‐out date were shown between provenances taken from throughout the range of Picea abies. These differences were related to latitude with provenances of high latitude leafing‐out first.