bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Adaptation of Plankton Algae
Authors: Nielsen E. Steemann , Jørgensen Erik G. 
Published: April 2006

AbstractThe various aspects of the adaptation of plankton algae lo light and temperature are discussed. The shape of a light intensity‐photosynthesis curve is shown to be an important means of describing the physiological adjustment of an algal population.If the algae are not exposed to adverse influences such as poisons, pronounced nutrient deficiency or light shocks, the rate of real photosynthesis per mg chlorophyll a at 1 Klux (incandescent light) should be about 0.4–0.6 mg C/hour. Hence this rate presents an excellent means of judging the quality of experiments.Experiments are presented where Chlorella pyrenoidosa was adapted to light intensities between 0.32 klux and 21 Klux. This alga adapts to different light intensities by varying the amount of pigments per cell. Algae grown at 1 Klux have about 10 times more chlorophyll per cell than those grown at 21 klux. Other species of algae—but by no means all—are shown to behave in the same way.The problem of algal resistance to photo‐oxidation at high light intensities is discussed. Adaplation is shown to he one of the mechanisms which make the algae resistent. “Chlorophyll inactivation” is another.Experiments with the diatom Skeletonema costatum concerning adaptation to different temperatures have been performed. The fact that the alga has essentially the same rate of photosynthesis per cell at all light intensities at 20°C and 7°C, may be attributed to an increase of all the enzymes at the low temperature. The amount of protein per cell was twice as high at 7°C as at 20°C.
Water and Sulphate Uptake at Root Reduction in Ricinus communis
Authors: Christersson Lars , Pettersson Sune 
Published: April 2006

AbstractThe aim of the investigation was to study the influence of the rate of water uptake on the uptake of sulphate at supernormal rates of water flow. This was achieved by reducing the size of the root system of 42 days old Ricinus plants. The rate of water flow through the root increased 3 times by reducing the root system to 20 percent. This did not change the retention of sulphate in the roots. The uptake of sulphate was proportional to the size of the root system and thus independent of the rate of water flow while the water uptake (transpiration) was a function of the size of the shoot and the resistance of the root. This was contrary to the conditions at a moderate rate of water flow, when water and sulphate uptake followed each other. The results are discussed in terms of the salt uptake as a series of active and passive processes.
The Adaptation of Plankton Algae
Authors: Jørgensen Erik G. 
Published: April 2006

AbstractThe theory that Skeletonema cells adapt to lower temperatures by increasing their enzyme concentration, is supported by various facts. While the rates of photosynthesis are identical in cells adapted to different temperatures (7–20°C) the growth rate decreases with decreasing temperature and the production of organic matter increases with decreasing temperature. Further, the concentration of protein per cell and the height of the cells increase with decreasing temperature.
Nucleic Acid Metabolism of Vicia faba during Germination and Growth
Authors: Olsson R. , Boulter D. 
Published: April 2006

AbstractDuring the growth of Vicia faba seedlings in the absence of an external nitrogen supply, the cotyledons decreased rapidly in dry weight and nucleic acid content. In the developing shoot the dry weight increased rapidly for four weeks and then very slowly over the next two weeks growth; the nucleic acid content of the shoot increased to a maximum after 4 weeks growth and decreased in amount during the next 2 weeks. On the other hand the roots increased in both dry weight and nucleic acid content throughout the growth period, although they only accounted for a small proportion of the total dry weight and nucleic acid content of the plant. These changes during germination and growth are discussed in relation to those occurring during these developmental stages in other plants.
Energy Sources for the Absorption of Rubidium by Chlorella
Authors: Sprimier‐Lederer Helmuth , Rosenfeld David L. 
Published: April 2006

ZusammcnfassungDie aktive (stoffwechselabängige) Aufnahme von Radiorubidium aus 8.10−5 molarer Lösung durch Chlorella pyrenoidosa wurde in Langzeitversuchen (1–2 Tage) untersucht. Die Annahinc ist, daβ die dafür notwendige Energie in Form von ATP bereitgestellt werden muβ. Es wurde gefunden, daβ Gegenwart von Na‐ Oder Cl‐Ionen für die aktive Rb‐Aufnahme nicht notwendig ist; die Rb‐Pumpe ist also nicht an eine Na‐ Oder Cl‐Pumpe gekoppelt. Vorbeladene Chlorella gibt Rb über längere Zeiten langsam an das Medium ab.Durch Experimente im Licht bzw. Dunkel und in Gegenwart bzw. Abwesenheit von Luft wurde gezeigt, daβ bei 9000 lux die Beleuchtung mehr Energie für die aktive Aufnahme erbringt als die Atmung. Der Ersatz von Luft durch Sauerstoff hat keine Auswirkung. Die Versorgung mit ATP durch Atmung—nicht aber durch (zyklische) Photophosphorylierung—wird durch 5.10−4 M DNP weitgehend unterdrückt. Die aktive Aufnahme ist klein, wenn sie sich nur auf Glykolyse stützt.Gleichzeitige Einwirkung von Licht, Luft (Sauerstoff) und DNP auf Chlorella führt zu irreversibler Schädigung und Ausbleichung der Algen. Sie hören auf, Rb aufzunehmen und verlieren vorher absorbiertes Rb wieder. Gründe für diesen Effekt werden diskutiert.Die aktive Aufnahme von Rb wird durch 5.10−2 M Glukose gefördert, u.z.w. im Licht und im Dunkel, in Luft‐ und in Stickstoffatmosphäre. In dieser Beziehung unterscheidet sich die aktive Rb‐ von der aktiven Bromid‐Aufnahme. Die Förderung durth Glukose wird durch DNP gehemmt, ausgenommen im Dunkel in Stickstoffatmosphäre. In Gegenwart von DNP wird die Rb‐Aufnahme durch 1% CO2 sowohl im Licht als auch im Dunkel stark herabgedrückt.
Some Observations on the Sodium and Potassium Interactions in the Blue‐green Alga Anabaena flos‐aquae A‐37
Authors: Bostwick C. D. , Brown L. R. , Tischer R. G. 
Published: April 2006

AbstractThe growth of Anabaena flos‐aquae A‐37 has been shown to be severely limited by the absence of either sodium or potassium from the culture medium. Neither element is capable of replacing the other. The addition of sodium to sodium‐starved cells restores growth while potassium‐starved cells are not affected by the addition of potassium.
Untersuchungen über Beziehungen zwischen Zellteilung und Morphogenese bei Gewebekulturen von Daucus carota
Authors: Linser Von H. , Neumann K. H. 
Published: April 2006

Abstract Relationship between cell division and morphogenesis of tissue cultures of Daucus carota. I. Observations on rhizogenesis and formation of whole plants.—By using a chemically defined medium the conditions for formation of roots and embryos in callus of various tap root parts of domestic Daucus carota forms were investigated and compared. Whole carrot plants capable of generative reproduction were produced from callus as well as from cell and tissue suspensions.The influence of various phytohormones on differentiation and cell division activity of explants was studied. A close relationship between cell division activity and differential stains was established and explained as a result of the phytohormone action on the cell division rate.
Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism
Authors: Wichner Siegfried , Libbert Eike 
Published: April 2006

AbstractHomogenates of epicotyls or roots of nonsterile pea plants incubated with tryptophan produce IAA within 1 to 4 hours, which was detected by means of the Avena curvature test and thin layer chromatography.Three results prove this short‐term IAA production to be mainly caused by epiphytic bacteria: 1) Homogenates of sterile plant parts catalyze a conversion of tryptophan to IAA, a hundredfold lower. 2) Chloramphenicol or streptomycin very actively reduce the IAA gain obtained with nonsterile homogenates. 3) Washing solutions of nonsterile plant parts which do not contain plant enzymes but only epiphytic bacteria, produce IAA from tryptophan, too.IAA synthesis from tryptophan in vitro by enzymes of the pea plant occurs with lower intensity than hitherto known; possibly it is physiologically unimportant. It is discussed to what extent the hitherto existing research work about the IAA biogenesis in higher plants might be incriminated by disregarding tbe rôle of epiphytic bacteria.
Untersuchungen über Beziehungen zwischen Zellteilung und Morphogenese bei Gewebekulturen von Daucus carota
Authors: Neumann K. H. 
Published: April 2006

Abstract Relationship between cell division and morphogenesis of tissue cultures of Daucus carota. II. Respiration of tissue cultures in relation to cell division.—The relationship between oxygen consumption and cell division activity has been studied in ex‐plants of the secondary phloem of the tap root of Daucus carota with respect to the influence of various phytohormones. An inverse correlation was found, i.e. explants with a high cell division activity had a low oxygen consumption and explants with a low cell division activity had a high oxygen consumption.
Biochemical Aspects of Parasitism by the Angiosperm Parasites: Starch Accumulation
Authors: Singh M. , Singh D. V. , Misra P. C. , Tewari K. K. , Krishnan P. S. 
Published: April 2006

AbstractThe investigation dealt with starch accumulation in four species of Cuscuta (Cuscuta campestris, C. indecora, C. planiflora and C. reflexa), a leafy mistletoe (Dendrophthoe falcata) and a chlorophyll‐lacking root parasite (Orobanche aegyptiaca). The highest content of starch occurred In O. aegyptiaca, with a maximum of 45 per cent of dry weight Starch in Cuscuta filaments and mistletoe leaves showed a maximum of about 10 per cent of dry weight. The starch content varied along the length of the Cuscuta vine, with a maximum in the apical region. Orobanche had a higher starch content when it was still submerged than it was fully developed. Cuscuta vines did not show any marked diurnal alteration in the starch content. The content of ethanol‐soluble carbohydrate was only a tenth of the starch in Orobanche, but was relatively higher in the other parasites. the neutral sugars in Cuscuta filaments were sucrose and glucose, whereas fructose was also present in mistletoe and Orobanche. Raffinose and stachyose were absent or present only ill traces in parasite tissue. Starch granules from Cuscuta and Orobanche bad ADPG/UDPG‐starch synthetase activity and homogenates starch phosphorylase activity. The former enzyme appeared to be responsible for synthesis of starch and the latter for utilization. The four different species of Cuscnta, growing on alfalfa, had more or less the same activity of starch synthetase and also of phosphorylase activity. Hosts infected by Cuscuta had significantly less starch per plant than the controls. A characteristic feature of invasion by Cuscuta and Orobanche was increased phosphorylase activity in the host tissues. The protein content of the tissues of Cuscuta and Orobanche was of a lower level than that of the host shoot system or foliage, indicating that the parasite differed from the host in having a higher carbon (of starch) to nitrogen (of protein) ratio.
Comparative Physiology of Respiration in Aquatic Fungi II. The Saprolegniales, Especially Aphanomyces astaci
Authors: Unestam Torgny , Gleason Frank H. 
Published: April 2006

AbstractThe endogenous respiration of six members of Saprolegniaceae (Oomycetes), Saprotegnia sp., Thraustotheca sp., Achlya sp., Dichtyuchus sp., Aphanomyces euteiches, and A. astaci were studied in the presence and in the absence of exogenous substrate using conventional manometric techniques. Glucose stimulated the rate of oxygen uptake of unstarved mycelia to some extent in all the fungi. Attempts to increase the weak stimulation of respiration by glucose in A. astaci were not successful. The respiratory quotients of the fungi tested were usually in the range of 0.7 to 0.9 during endogenous respiration, and addition of glucose increased these values more than expected.L‐leucine and L‐glutamic acid stimulated respiration of A. astaci only when the fugus was starved, and acetic acid and butyric acid were inhibitory. Fructose and acetic acid increased respiration in starved mycelium of A. euteiches while L‐leucine and L‐glutamic acid had little effect. Antimycin A, HOQNO, HCN, and fluoroacetate strongly inhibited endogenous oxygen uptake by A. astaci. Amytal and azide were also markedly inhibitory while rotenone and CO had little effect. DNP and diphenylamine inhibited respiration at a high concentration but at a lower concentration DNP was stimulatory. In contrast the respiration of Saprolegnia sp. was resistant to cyanide, antimycin A, and HOQNO.Spectrophotometric observations on homogenized mycelia of Saprolegnia sp. and of A. astaci indicated the presence of cytochrome c (551 nm), two b‐type cytochromes (557 and 564 nm) and cytochrome a‐a3 (605 nm) all in approximately equimolar concentrations. In both strains CO combined with cytochrome a3 and an unidentified pigment. A remarkable similarity in the cytochrome system seems to exist between these two strains and some members of the Leptomitales.
Leaf Expansion in the Potato, Solanum tuberosum
Authors: Lovell Peter H. 
Published: April 2006

AbstractThe effects of a number of manipulative treatments together with the application of the growth hormones IAA and GA on leaf expansion in the potato, variety Majestic, were investigated. It was found that removal of the apex and its surrounding non‐expanded leaves resulted in an increase in both the rate and the extent of expansion of Ihe remaining upper leaves on the system. Application of IAA and GA to decapitated shoots showed that the rate of leaf expansion was decreased by IAA both alone and in combination with GA, whereas it was increased by GA treatment. Further investigations indicated that the response of a leaf to GA treatment was determined by the area and position of the leaf al the time of treatment and also by the number of expanding leaves on the system. It is postulated that this is due, at least in part, to competition for some factor or factors, which could be nutrients, within the system.
The Adaptation of Plankton Algae
Authors: Nielsen E. Steemann , Jørgensen Erik G. 
Published: April 2006

AbstractA survey of the adaptation of plankton algae in Nature to different light intensities and temperatures is given. The adaptation is always important for the plankton populations at all depths. However, the shade adaptation of the algae in the lower part of the photic zone is often of relatively little importance for the integral primary production per unit of surface, except on the by no means rare occasions when the bulk of the algae is found in this lower part. It is shown that the Ik of surface plankton during summer in the Arctic is high despite the low temperatures present. This is due to an increase of the enzyme quantities per cell. Daily fluctuations in Ik are due partly to photooxidation, partly to the fact that the periods for the production of chlorophyll and photosynthetic enzymes are mutually displaced. Despite the daily fluctuations in Ik the difference between “sun” pbytoplankton and “shade” pbytoplankton is distinct.
Blatt‐Atmung der höheren Bodenpflanzen im tropischen Regenurwald
Authors: Löhr Erika , Müller D. 
Published: April 2006

Abstract Respiratory Activity in Leaves from Herbs in the Tropical Rain Forest.—Plants of the undergrowth flora In the tropical lowland rain forest have typical shade‐leaves distinguished by low dry matter percent, large leaf area per gram fresh weight and very low respiratory intensity per unit area of leaf blade. When the respiratory intensity measured at 26°C is converted to 20°C, the values lie somewhat lower than those for extreme shade‐leaves of the temperate forests of Denmark. The leaf blades of Lomariopsis guineensis have on the whole the lowest respiratory intensity so far measured in leaf blades: 0.06 mg CO2 per 50 cm2 leaf blade (one side only) and hour at 20°C. The semisucculent shade‐leaves of Palisota hirsuta constitute an exception with regard to area per gram fresh weight, in which respect they resemble the semi‐succulent shade‐leaves of the fern Ophioglossum vulgatum in Denmark.Die Bodenflora von höheren Pflanzen in einem tropischen Regenurwald im Tiefland besteht teils aus Kräutern, teils aus kleinen Bäumen, die eventuell zu grossen heranzuwachsen vermögen; dagegen sind absolut keine Straucher vorhanden. Die Blatter von einigen Kräutern im Urwald bei Adiopodoumé, Elfenbeinsküste, (5°, 20’ nördl. Br, 4°, 10’ west. L) wurden untersucht und zwar folgende: Aframomum sceptrum Schum. (Zingiberaceae), Palisota hirsuta Schum. (Commelinaceae) und Lomariopsis guineensis Kuhn (Farn aus der Familie Polypodiaceae).
Activation of Enzymes during Germination: Amylopectin‐1,6‐glucosidase in Peas
Authors: Shain Y. , Mayer A. M. 
Published: April 2006

AbstractDevelopment of amylopectin‐1, 6‐glucosidase (amylopectin 6‐ glucanohydrolase) activity in germinating peas occurs under conditions in which protein synthesis is inhibited and α‐ and β‐amylase fail to increase in activity. An increase in activity of amylopectin 6‐glucanohydrolase can be obtained in cell free homogenates of imbibed pea seeds under autolytic conditions. Activation is shown to occur in a particulate fraction and to be due to the action of a proteolytic enzyme in the homogcnates. A system could be constituted consisting of a particulate fraction and trypsin which lead to a rapid activation of the amylopectin 6‐glucanohvdrolase. This is regarded as proof that enzymes in germinating seeds can be formed by liberation or activation of precursor forms. The implications of this are discussed.
Studies of the Growth in Culture of Excised Wheat Roots
Authors: Talbot Beryl , Street H. E. 
Published: April 2006

AbstractAeration of root culture medium with air containing 5 % or 10 % CO2 enhances growth, particularly lateral initiation and growth, compared with aeration wilh air or CO2‐free air. This beneficial effect of enhanced CO2 pressure on the growth of cultured roots of Atson Elite 56 wheat ean also be demonstrated in presence of a high (40 %) and inhibiting level of oxygen. 14C labelling from a carbonate–bicarbonate solution of pH 7.0 by cultured wheat roots is enhanced by light and this labelling is not inhibited by the presence of 1 % ethyl urethane.
Movement of Amyloplasts in the Root Cap Cells of Geotropically Sensitive Roots
Authors: Iversen Tor‐Henning , Pedersen Knut , Larsen Poul 
Published: April 2006

AbstractThe root cap of Lepidium sativum under our culture conditions was found to contain 7 (or occasionally 8) storeys of starch‐containing cells. In the youngest one (or two) of these storeys the amyloplasts are small and the cells appear embryonic. In the 6 non‐embryonic storeys the amyloplasts are large. Upon inversion of the root, the amyloplasts in the 3 youngest of the 6 non‐emhryonic storeys start falling toward the opposite end of the cell at about 72 μ per h (at 21 C), hut they maintain this speed for only 6 to 12 min, after which they virtually come to a stop. As a result, it takes 10 to 12 min before any of the amyloplasts get approximately as close to the ceiling as they were to the floor before the inversion; and this is true only of the 2 youngest of the non‐embryonic storeys. When the root is placed horizontal, whether coming from the normal or the inverted position, the amyloplasts reach the lower, longitudinal wall in 15 min or less. The positions of the amyloplasts in the cells of the 3 oldest starch‐containing storeys are erratic and show little, if any, dependency on the preceding time of inversion.
Effect of Kinetin on Ribosomes of Excised Barley Leaves
Authors: Srivastava B. I. Sahai , Arglebe C. 
Published: April 2006

AbstractThe changes in the amount and the composition of ribosomes in excised barley leaves floated on water or on 10 mg/l kinetin solution in the dark were examined.The rapid loss of polyribosomes and ribosomes in leaves floated on water was greatly retarded by kinetin. The ribosomes‐polyribosomes which originally contained 49 per cent protein showed substantial decline in protein content in leaves floated on water but only slight decline in leaves floated on kinetin solution. It is suggested that kinetin by stimulating RNA synthesis and by suppressing the activities of rihonuclease and peplidase may preserve the ribosomes in excised leaves.
Accumulation and Disintegration of Starch in the Chloroplasts of Stellaria media Grown under Constant Illumination
Authors: Haapala Heikki 
Published: April 2006

AbstractThe persent paper contains a study un the starch content of the chloroplasts of the leaves of Stellaria media, performed by hsitochemical methods. Three leaves were collected at short intervals, fixed and cut in 10 μ sections, and stained according to the PAS‐procedure. The starch content of single chloroplasts was measured by a microscope photometer. The chemical composition of the stainable material was demonstrated by enzyme specific experiments.At the end of a 12 hours' dark period the chloroplasts contained only traces of starch. Light caused the starch accumulation to begin and after a time chloroplasts seemed to be filled with starch. Subsequently, however, a sudden decrease in the starch content of the chloroplasts took place, in spite of constant illumination. A rather high level of starch content was restored in a few hours.The author puts forward some ideas about the nature of the factors causing the transitory disintegration of starch in illuminated leaves. The induction or the activation of certain enzymes seems to be the most probable explanalion.
Inducible Formation of Urease in Canavalia ensiformis
Authors: Matsumoto H. , Hasegawa Y. , Kobayashi M. , Takahashi E. 
Published: April 2006

AbstractIncrease in urease activity in leaves of Canavdlia ensifomis has been demonstrated. The activity of excised leaves increased by about 100 percent when 1.5 × 10−1M urea was added externally as inducer. Glycine‐1‐14C was used to investigate whether the increase in activity was dependent on de novo protein synthesis. The Incorporation of labeled amino acid into urease was twofold higher in induced samples than in non‐induced ones. This indicates that the increase in activity is connected with de nova protein synthesis. The once increased activity was always followed by a rapid decrease. The urease activity was lost constantly with time after the external addition of ammonia in vivo. The inhibitory action of ammonia on urease fa vitro was eliminated by dialysis. Accordingly it may be concluded that the loss of activity was dependent on the product repression by ammonia.
Effect of Uracil and 5‐Nitrouracil on Growth and Flowering of Tomato
Authors: Mathur S. N. , Sharma R. A. 
Published: April 2006

AbstractThe effects of uracil and its analogue 5‐nitrouracil on growth and flowering of tomato have been studied. A few drops (0.3 ml) of solutions containing 15, 30, 60, 90 and 150 μg of each prepared from a stock of 500 mg/I in glass redistilled water were applied per plant on 3–4 top leaves and the apex of one month old seedlings with 6–7 leaves. A second application double in volume of the same chemicals was made on the same plants a week later. The controls were given a distilled water treatment.Treatments with uracil and 5‐nitrouracil significantly increased the plant height and the fresh and dry weights of the shoot. Higher concentrations (500 mg/I) had no promotive effect. Although there had been a significant promotion of the leaf and stem growth, the root growth and the nodes were unaffected.Flowering was significantly hastened by both bases. Treatments with uracil also resulted in the formation of more flowers. Uracil and 5‐nitrouracil also caused significant increases in the total‐N of the leaf and the stem, and the effect on protein metabolism seems to be localised where they act as RNA metabolites. The presence of the nitro‐group in 5‐nitrouracil does not act as an additional source of nitrogen for protein metabolism as it did not have more promotive effects than uracil.