bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Physiology of Zoospore Production in Aphanomyces astaci
Authors: Unestam Torgny 
Published: April 2006

Abstract Aphunomgces astaci, Saprolegniaceae, the crayfish plague parasite, grows well in a buffered peptone ‐ glucose ‐ mineral salt medium but does not normally produce spores during growth in this medium. Sporulation is, however, easily induced by transfer to pond water. None of the components of the complete medium inhibited sporulation more than partly when tested solely or in combinations. Neither lack of oxygen, high carbon dioxide concentrations, nor osmotic phenomena could satisfactority exlpain the absence of spore formation in the complete medium. In a peptone ‐ glucose growth medium low in phosphate and metal salts a sporulation inhibiting factor was formed by the mycelium. In this medium both good growth and good spore production could, however, occur simultaneously and spore production was here stimulated by a reduction in the oxygen tension. Liberation of formed spores into the medium was inhibited by mineral salts. It was less sensitive to lack of oxygen, respiratory inhibitors, and a factor formed during growth than was sporangial development. Development and maintenance of spore motility occurred even at very low oxygen tensions but was probably dependent upon an intact respiratory system.
The Mode of Action of Maleic Hydrazide: Inhibition of Growth
Authors: Noodén Larry D. 
Published: April 2006

AbstractMaleic hydrazide (MH) inhibits corn root elongation through an effect on cell division apparently without inhibiting cell enlargement. The decrease in the rate of elongation was apparent only after a considerable lag, over 14 hours, even with a concentration as high as 5 mM. MH (1 mM) did not inhibit His growth of roots from corn seeds given very large doses of γ‐irradiation or excised corn root segments including the elongation Zone or the cell enlargement induced by IAA in corn coleoptile sections. Many compounds including purines, pyrimidines, nucleosides. cysteine, pyridoxal, pyruvate. kinetin and CoCl2, many of which had previously been reported to alleviate MH inhibition in other tissues, were tested for their ability to prevent the inhibition of corn root elongation by MH, but none were effective. These data do not support the theory that MH acts by inhibiting the synthesis of or competing with some simple metabolite or hormone. Whatever its mechanism of action the failure of MH to inhibit cell enlargement in most systems indicates that it is fairly selective.
Effects of Intermittent and Continuous Light on the Chlorophyll Formation in Etiolated Plants at Various Ages
Authors: Akoyunoglou G. , Argyroudi‐Akoyunoglou J. H. 
Published: April 2006

AbstractThe effect of the tissue age of dark‐grown bean plants on the chlorphyll formation under continuous illumination or short impulses of white light has been studied. It was found that the protochlorophyllide present in the tissue is age‐dependent and reaches a plateau at about 10 days of age, as judged by the chlorophyll formed in etiolated plants of various ages after 5 min illumination.The amount of chlorophyll a and chlorophyll b formed under short impulses of while light increases up to about 9 days of age and thereafter decreases. However, the decrease in chlorophyll a is sharper than that of chlorophyll b, the amount of which remains almost constant.The ratio of chlorophyll a lo chlorophyll b under the short impulses of white light is higher in the younger plant. Similar results are obtained after transfer of the plants from the flashing light to continuous illumination In the young plant there is no lag phase in the chlorophyll biosynthesis while as the age is increased the lag phase is evident and its duration increases as the plant ages.After protochlorophyllide phototransformation under continuous illumination the lag phase in chlorophyll biosynthesis is also age‐dependent. Leaves up to 5 days old show no lag phase in chlorophyll synthesis; after this point, however, the lag phase's duration increases continuously with age.
An Asymmetric Respiratory Response Occurring when Fluoride and Copper Ions are Applied Jointly to Chlorella vulgaris
Authors: Hassall Kenneth 
Published: April 2006

AbstractWhen a cell suspension of Chlorella vulgaris is treated with a mixture of copper and fluoride ions, the respiration almost ceases even though the two ions individually have lit t le inhibitory effect. If instead of adding the ions simultaneously, the cells are subjected to a period of pretreatment with copper sulphate before sodium fluoride the inhibition of respiration becomes more severe as the pretreatment time is lengthened, except at copper levels so high that inhibition is almost complete at all lengths of pretreatment. When, however, pretreatment is with fluoride ions, the inhibition becomes less as the pretreatment time is lengthened, eventually disappearing when the time interval is 90 min or more. Measurements of the amount of copper in the cells indicate that this asymmetry of response cannot be ascribed to differences in the rate at which copper is taken up. It is suggested that fluoride blocks the main respiratory pathway and that copper probably blocks the hexose monophosphate shunt.
Further Studies on Factors Affecting the Efflux of Betacyanin from Beet Root: A Note on Thermal Effects
Authors: Siegel S. M. 
Published: April 2006

AbstractAs judged by betacyanin efflux, beet root tissue differs in stability toward O2 at low and high temperatures (45–60°C and 60–100°C respectively). The effect of temperature itself can he divided into a high activation energy (93 Kcal mol−1) process in the lower temperature range and a low activation energy process (19 Kcal mor−1) in the higher range (> 60°C). From these data it is suggested that initially, elevating temperatures bring about reversible conformational changes in the membrane. With continuing increase in temperature in the presence of O2, membrane chemical groups susceptible to oxidation are exposed and, upon oxidation, render conformational changes irreversible.
Studies on the Germination of Pine Pollen (Pinus mugo) in vitro. I. Growth Conditions and Effects of pH and Temperature on Germination, Tube Growth and Respiration
Authors: Nygaard Per 
Published: April 2006

AbstractThe ability of pine pollen to grow in vitro is discussed in relation to its in situ. Optimal conditions of growth in vitro were investigated. All the experiments were made with pollen of Pinus mugo Turra.A satisfactory medium is described as that which at pH 5.2 and at 29 °C can lead to a tube growth bigger than in vivo. The initial growth (0–30) hours) in terms of tube growth and respiration is described in detail. It is shown that a correlation exists between tube growth and respiration. A method for estimating the metabolism and growth of the pollen tube, based on the uptake of 32p‐labelled phosphate, is described. Addition of known stimulators of plant growth and extension does not stimulate tube growth. Temperature studies show that under 20°C germination does not take place.
Differential Inhibition of Cell Division in Euglena gracilis by Cysteamine and Cystamine
Authors: Nissen Per , Eldjarn L. 
Published: April 2006

AbstractCysteamine (2‐aminoethanethiol) inhibited cell division in synchronously dividing cultures of Euglena gracilis at relatively low concentrations (0.005 M), Cystamine (2,2′‐dithiobis(ethylamine). however, was only partially inhibitory at high concentrations (0.1 M). This differential inhibition may reflect certain unique features of nuclear division in euglenoid flagellates.
Effects of Daylength and Time of Application of Phosphorus on Growth and Grain Yield of Wheat
Authors: Smith A. N. 
Published: April 2006

AbstractThree varieties of wheat. Thatcher, Falcon and Sunset. were grown under 20. 12 or 8 hour days until the initiation of spikelet primordia on the shoot apex began, and then in natural light until maturity. Phosphorus (100 mg/l P) was applied at 7, 33 or 54 days after sowing, other plants were left without phosphorus. The response of the plants to phosphorus in terms of final leaf number, grain production and number of fertile spikelets was related to time of initiation.When the time of initiation was 52 or more days after sowing there were some responses in grain yield to phosphorus, but they were independent of time of application; for initiation times of 32 days or less the earlier applications of phosphorus tended to give a greater response.
Isoenzyme Changes during Seed Germination of Saguaro Cactus (Carnegiea gigantea)
Authors: Keswani C. L. , Upadhya Mahesh D. 
Published: April 2006

AbstractEsterases, acid phosphatases, leucine aminopeptidases, peroxidases and glutamic‐oxalacetic transaminases from extracts made from seeds of Saguaro cactus at different stages of germination were studied using starch gelelectrophoretic techniques. In general, four of the five enzyme systems showed significant increase in the number of isoenzymes and their activity after 72 hours of germination. It is suggested that Saguaro cactus seeds reach their enzymatically most active state between 48 to 72 hours after being placed at optimum moisture conditions at 30°C in continuous light.
Fertilization‐induced Chemotaxis in the Zygotes of the Watermold Allomyces
Authors: Machlis Leonard 
Published: April 2006

AbstractZygotes obtained by self‐fertilization of Allomyces macrogynus, strain Burma 3 and of A. arbuscula, strain Ceylon 1, behave chemotactically as do their respective zoospores. All the swarmers respond to an equimolar mixture of L‐leucine and L‐lysine with the response enhanced by the addition of L‐Proline. The A. arbuscula swarmers also respond moderately to a mixture of L‐proline with certain amino acids other than leucine and lysine whereas those of A. macrogynus do not.The gametes are not chemotactically responsive to the amino acids. Within no more than five minutes subsequent to fertilization, the zygotes become chemotactically active.The genetically‐derived, approximately 95 % male or female isolates do not appear to form zygotes when crossed. The few zygotes observed in a series of attempted crosses appear to be the result of selfing by the contaminating opposite sex in each of the highly unisexual strains.
Auxin Physiology of Dwarfism in Pisum sativum
Authors: Lantican Beatriz P. , Muir Robert M. 
Published: April 2006

AbstractSimilar levels of diffusible auxin are measured for the apices of both Little Marvel (dwarf) and Alaska (normal) cultivars of the pea when grown in sunlight and darkness. In sunlight, however, diffusible auxin disappears in the subtending internode of the Little Marvel plant but remains at 50 per cent of the level of the apex in the subtending internode of the Alaska plant. The enzyme preparation from the apex of the dwarf plant converts tryptophan and tryptamine to IAA more readily than that from the normal plant. Indoleacetyl aspartate synthetase activity is also higher in the dwarf plant than in the normal plant and the dwarf plant contains four times as much conjugate as the normal plant with or without treatment with gibberellic acid. Gibberellic acid (GA) does not affect the induction of the synthetase enzyme nor the enzymatic formation of indoleacetyl aspartate. The growth induced by GA is the result of an increased synthesis of auxin.
Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism VI. The Influence of the Epiphytic Bacteria on the Content of Extractable Auxin in the Plant
Authors: Libbert Eike , Kaiser Wolfgang , Kunert Reinhard 
Published: April 2006

AbstractSterile plants of maize, pea, and cucumber contain less auxin (extracted with methanol or ether) than nonsterile ones. The auxin content is restored within one day by reinfecting sterile plants (or only the shoots, with roots and culture medium remaining sterile) with epiphytic bacteria strains able to produce IAA or with soaking water of nonsterile seeds. Reinfection with bacteria, strains unable to produce IAA is ineffective. — The possibility of a bacterial auxin production during methanol extraction was excluded.
Studies on Sugars and Starch in Light‐ and Dark‐Germinated Seeds of Scots Pine (Pinus silvestris)
Authors: Nyman Bengt 
Published: April 2006

AbstractStachyose, raffinose and sucrose have been tentatively identified in ungerminated Scots pine seeds with paper chromatography and TLC. After the onset of the germination process even glucose and fructose were detected. No free galactose has been found. The occurrence and distribution of starch has been investigated with histochemical technique. The same substances have been quantitatively studied during the first 24 hours of the germination in light and darkness. This was done with an enzymatic technique alone or in combination with TLC. The evidence of a light influence on the transformations of starch, glucose and fructose has been discussed in relation to the phytochrome mechanism.
Cytokinins and Transfer Ribonucleic Acids. II. Presence of Cytokinins in Different Amino‐acid Specific Transfer Ribonucleic Acids of Brewer's Yeast as Revealed by the Growth Response of Tobacco‐pith Callus Tissue and Scorzonera Crown‐gall Tissue
Authors: Giannattasio M. , Jeannin G. , Kovoor A. 
Published: April 2006

AbstractSoluble ribonucleic acid of brewer's yeast was fractionated by countercurrent distribution and assayed for certain amino‐acid acceptor activities, as well as for cytokinin activity, using both tobacco pith callus tissue and Scorzonera crown‐gall tissue.An undetermined fraction of ribonucleic acid, rich in cytokinin and similar to one previously reported for baker's yeast, was observed. Two species of cytokinins, probably different from isopentenyl adenine, were detected in other ribonucleic acid fractions by comparing their activities on the two tissues used in growth tests. They do not seem to be located in any of the specific amino‐acid accepting transfer ribonucleic acids determined in this study.
Photomorphogenic and Chlorophyll Studies in the Bryophyte Marchantia polymorpha
Authors: De Greef J. , Fredericq H. 
Published: April 2006

AbstractBesides the standard rod (R) and far‐red (FK) irradiations, a graded series of different R/FR ratios were tested as 10 min terminal exposures at the end of the daily 8‐hour photoperiod of white fluorescent light. Water filtered incandescent light of 3780 lux during 10 min caused A rather weak hut reproducible effect. A superposition to the water layer of different filter combinations shifting the initial transmittance more towards the FR region, and thus gradually lowering the R/FB ratio, resulted in a parallel increase in orthotropic growth and a decrease in chlorophyll content. Our data show growth similarities with the results of other authors on light grown seedlings of higher plants. Rather high levels of the PFR form of phytochrome seem to he required to maintain horizontal growth and optimal chlorophyll content in Marchantia thalli.
The Optimum Angle of Geotropic Stimulation and its Relation to the Starch Statolith Hypothesis
Authors: Larsen Poul 
Published: April 2006

AbstractRoots which are turned from their normal direction to directions at various angles with the plumb line develop the largest geotropic curvatures during a subsequent klinostat rotation period when the stimulation angle is well above the horizontal. In experiments with roots of Lepidium sativum L., the optimum is located at 120 to 140° when the stimulation time is between 2 and 15 min. If this fact is to be explained by the movements of amyloplasts in the root cap cells, one would expect roots which bad been kept inverted before the stimulation (so that the moveable amyloplasts are accumulated in the opposite end of the cells) to show an optimum angle well below 90°. — Pre‐inversion of the roots did suppress the curvatures produced by stimulation at angles larger than 90° when measured after 10 to 30 min of klinostat rotation. This suppression may be taken as a support for the starch statolith hypothesis, since the amyloplasts in pre‐inverted roots placed at angles exceeding 90° have a restricted opportunity to slide along the cell walls compared to non‐inverted roots placed at the same angles. In pre‐inverted roots measured after a period of klinostat rotation, however, no optimum was found at angles below 90°. When the stimulation time was 3.75 min, the response curves were nearly symmetrical about 90°. Stimulation for 15 min, on the other hand, resulted in curvatures which were much larger (although suppressed in comparison with non‐inverted roots) when the stimulation angle was 165° than when it was 15°. During the 15 min stimulation period itself, however, pre‐inverted roots curved 0.3° when stimulated at 15, but only 3.4° at 165°. This small difference was very highly significant and is in agreement with the starch statolith hypothesis insofar as the amyloplasts in pre‐inverted roots placed at 15° have the greatest opportunity to slide along the cell walls. The lack of further development (and the actual decrease) of their curvatures during the subsequent klinostat rotation must then be due to other, depressing, factors, summarily designated as tonic. At angles above 90°, the tonic factors are either absent or even enhancing. Tbe tonic effects cannot be explained by amyloplast movements.
Untersuchungen zur Wirknngsweise der Aminosäure‐konjugate der Auxine in waehsenden Geweben
Authors: Kazemie Mirabotalib , Klämbt Dieter 
Published: April 2006

Abstract Growth effect of auxin‐amino acid‐conjugates in some test tissues.— Three different amino acid conjugates of the auxin naphthalene‐1‐acetic acid (NAA)‐naphthaleue‐1‐acetyl‐L‐aspartic acid, naphlhalene‐1‐acetyl‐D‐aspartic acid, and naphthalene‐1‐acetyl‐L‐glutamic acid — have been prepared and tested for growth stimulation in tobacco callus tissues, sunflower hypocotyls, and wheat coleoptiles. All conjugates show less auxin activities than NAA. The ratios of concentrations for more or less the same growth stimulation are 1:25 to 1:100 and less. Each test tissue grows the least on the D‐aspartic acid conjugate. These results lend to the conclusion that growth stimulation by these conjugates has lo be an indirect one, probably due to their hydrolysis generating free auxins. It is unknown whether the hydrolysis takes place inside or outside the cells.
Translocation of the Herbicide Dicamba in Purple Nutsedge, Cyperus rotundus
Authors: Ray Bibhas , Wilcox Merrill 
Published: April 2006

AbstractPairs of nutsedge plants connected by rhizomes were planted, each in a separate pan, without cutting the rhizomes. One plant within each pair was treated with 5.7 kg of dicamba per hectare seven days later. Ten days after treatment, the treated plants and those plants attached to them by rhizomes were harvested separately and analyzed by gas chromatography. The attached plants were found to contain 6 per cent as much dicamba as did the directly treated plants. The suspected metabolites, 3,6‐dicblorosalicylic acid, 3,6‐dicblorogentisic acid and 5‐HO‐dicamba, were not detected.
Adaptations in Pigment Composition and Photosynthesis by Far Red Radiation in Chlorella pyrenoidosa
Authors: ÖQuist Gunnar 
Published: April 2006

Abstract Chlorella pyrenoidosa has been cultivated in radiation of wavelengths between 690–975 nm for several months. Absorption spectra and action spectra of photo‐synthesis have been determined for far red and “white” light brown cultures, In vivo spectrophotometric analyses and action spectra showed that fur red growth Chlorella adapted to the extreme light conditions by an increase both in absorption and photosynthesis above 700 nm. It is proposed that som of the in vivo normal chlorophyll a forms were converted to a far red absorbing chlorophyll a form, giving the far red exposed suspension an increased photosynthetic activity between 700–740 nm. The analyses of far red grown Chlorella have also shown an increased photosynthesis in the blue part of the spectrum, presumably due to a decrease in photosynthetically inactive carotenoid content. By culturing Chlorella in a “white” light gradient between 0.5 × 104 and 3.7 × 104 erg cm−2 s−1, it has been demonstrated that light intensity did not influence pigment ratios between 500–750 nm. In the blue part, however, high light levels caused increased absorption because of increased carotenoid content. Some ecological aspects of this far red effect have also been discussed.
Some Forms of Phosphorus in Wheat Grain and Their Dependence on Mineral Nutrition
Authors: Sarić M. , Grujić S. , Petrović M. , Adamov I. 
Published: April 2006

AbstractThe contents of some forms of phosphorus (lipid, soluble, phytin, nucleic) were investigated in grain of wheat, variety “Mara”.The plants were grown in water culture using a Reid‐York nutritive solution. After 15 or 30 days one of the following elements was eliminated: nitrogen, phosphorus, sulphur, calcium or magnesium.The results show that the phosphorus contents of the different forms were lower in grain from the field than in that from the water cultures. The deficiency of the individual elements during vegetation affected the grain weight and the contents of the investigated forms of phosphorus, which fact indicates that different mineral nutrients have different effects on the metabolism of phosphorus.
The Suppression of Stareh Synthesis and the Accumulation of Uridine Diphosphoglucose in Cucumber Leaves due to Ammonium Toxicity
Authors: Matsumoto H. , Wakiuchi N. , Takahashi E. 
Published: April 2006

AbstractThis work is a study of the metabolic disorder due to ammonium toxicity in cucumber (Cucumis sativus L. cv. suisei No. 2) leaves. The cucumber was cultured with 20 and 200 mg/l NH3‐N for 5 days. In the first half of this experiment, the plant leaves were photosynthesized for 3 hours to study the distribution of 14C in starch and other fractions. The incorporation of photosynthesized 14C into not only starch but also other higher polymers was suppressed by ammonium toxicity. On the other band, the rate of 14C incorporation in 80 % ethanol soluble fraction was higher in the treatment of 200 mg/l NH3‐N. In the latter half of experiment, phosphate esters in the loaves were analyzed by column chromatography. The opposing contents of uridine diphosphoglucose (UDPG) and the uridine compound containing sugar or sugar derivative (UDPX) were determined by different ammonia levels. Toxicity of ammonia resulted in an increase of UDPG and a decrease of UDPX. The level of ATP was not changed so much. The content of glucose‐6‐phosphate (G‐6‐P) in injured plants was lower than that of normal plants, while ghicose‐1‐phosphate (G‐1‐P) and fructose‐6–phosphate (F‐6‐P) were higher in injured plants. These results further suggested the disorder of carbohydrate metabolism due to ammonium toxicity which was reported previously.