bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the Crayfish Plague Fungus Aphanomyces astaci
Authors: Unestam Torgny 
Published: April 2006

AbstractA mycelial suspension of the crayfish plague fungus, Aphanomyces astaci, was able to produce large numbers of zoospores, when transferred to redistilled water, at 20°C, even after storage for months at 2°C. Spore production was greater in redistilled water than in tap water and heavier under shake conditions than under stationary ones. In buffered redistilled water sporulation occurred between pH 5 and 8 and the optimal range was about pH 5 to 7.Of the tested aliphatic alcohols, aldehydes, and carboxylic acids, the long analogues were more toxic to spore formation than the shorter ones. Ethylenediamine‐tetraacetic acid (EDTA) prevented sporulation probably by removing some essential metal (s) with an affinity for EDTA near that of calcium. Calcium protected against the toxic effect of lithium, sodium, and potassium. Magnesium, only tested against lithium, had no such protecting effect.Cu2+, Ni2+, Zn2+, Co2+, K+ Mn2+, NH4+, Li+, Na+, Ca2+, Mg2+ was the approximate order among tested cations in their ability to stop the swimming stage of the zoospores, the first mentioned being the most effective ones. Nitrate and acetate were more active in the same respect than sulphate, chloride, phosphate, or bicarbonate. The optimal pH range for swimming seemed to be pH 6–7.5, and the maximal range 4.5–9.0.The zoospores showed no chemotactic response to tested substances. The germination ability was as high in horse blood as in crayfish blood. A spore suspension stored for 2 months at 2°C still contained viable spores.
Chitinolytic, Cellulolytic, and Pectinolytic Activity in vitro of Some Parasitic and Saprophytic Oomycctes
Authors: Unestam Torgny 
Published: April 2006

SummarySeven lower phycomycetes, Afhanomyees astaci, A. euteiches, A. cladogamus, A. cochlioides, A. laevis. Pythium sp and Saprolegnia sp., have been investigated in respect of chitinolytic and cellulolytic activity. The five Aphanomyces species were also tested for pectinolytic activity. Different ages of stationary and shaken cultures, 2 or 3 different substrates, and 2 test pH were used for each enzyme to be tested. Chitinase and cellulase were assayed with 2 different methods.All the fungi showed chitinase activity, although in varying degree. In liquid cultures the strains of A. astaci gave the by far highest ac tivity. Differenl results were obtained with different growth media aud lest methods.Chitinase of some of the fungi was readily adsorbed on chilin. Adsorbed chitinase seemed to withstand heating more than unadsorbed enzyme.Only the three plant parasites, A. euteiches, A. cladogamus and A. codilioides, showed appreciable cellulase and pectinase activities which in some cases were stimulated by the presence in the medium of the enzyme substrate.Different assay methods and growth conditions showed difterent pattern regarding the difference in activity between the tested fungi and between used media.The conceivable roles in vivo of found activities were discussed.
Mangan‐Einfluss auf Volumen und osmotischen Wert des Exsudats junger Sonnenblumen
Authors: Höfner W. , Herwig K. 
Published: April 2006

Zusammenfassung

In Versuchen mit jungen Sonnenblumen wurde der Einfluβ von mangan auf Volumen und osmotischen Wert des Exsudats innerhalb zweier Tage nach dem Abschneiden untersucht.
Zwischen Volumen und osmotischem Wert des Exsudats konnte keine direkte Korrelation ermittelt weden.
Die osmotischen Werte des Exsudats lagen zwischen 0.18 und .12 alm and verringerten sich im laufe des 1. Tages kontinuierlich. Am 2. Tag blieben sie annachernd konstant. Eine Ausnahme bildete nur die Versuchsreihe mit der hochsten Mn‐Steigerun, die den zu Angang gemessenen hohen Wer nach geringfugiger Abnahme wahrend des 1. Tages bis zur zweiten Abanahme des 2. Tages fast wider erreichte, dann aber wegen des Absterbens der Pflanzen nicht weiter verfolgt werden konnte.
Die Volumina des Exsudats verringerten sich zwar ebenfalls int Laufe des 1. Tages doch erfolgte am 2. Tag mittags ein vermutlich durch die Tagesrhy thmik der Pflanzen bedingler Anstie der Exsudatproduktion, ohne dass die osmotischen Werte starkere Zunahmen erfubren.
Von der letzten Abnahme des 1. Tages an fuhrte die Mn‐Steigerung zu einem gesicherten Anstieg des osmotischen Wertes, ohne jedoch einen Einfluss aut die Exsudatproduktion nach sich zu zichcn.
Der fordernde Einfluβ von Manan auf die Exsudatproduktion konnte crnent bestatigt werden.
Carotenoid Synthesis in Leaves of Wheat after Irradiation by Red Light
Authors: Virgin Hemming I. 
Published: April 2006

AbstractA short inipulse of red light induces a Carotenoid synthesis in dark‐grown wheat leaves. This effect is particularly evident if the leaves, having received a short light impulse, are kept in darkness for six hours prior to a period of continuous irradiation for six hours. During this second period of irradiation much more carotenoids are formed than during an irradiation period of the same length, but not preceded by a pre‐irradiation. The main increase in pigment contents can be brought back to β‐carotene. For this pigment the short light impulse nearly doubles the pigment synthesis during a subsequent dark and light period of six + six hours as compared to the amount formed during six hours of light without pre‐irradiation.
Growth Rates of Marine Phytoplankton: Correlation with Light Absorption by Cell Chlorophyll a
Authors: Eppley Richard W. , Sloan Phillip R. 
Published: April 2006

AbstractTo better predict plant production in the sea, it would be desirable to be able to calculate, from easily obtainable measurements at one sampling, the growth rate of the prevailing stock of phytoplankton. To this end growth rates, pigment composition, cell volume and cell surface area data were collected for several species of marine phytoplankton in logarithmic growth at 20–21°C and 0.07 cal/cm2. min light intensity. Similar data for one species, Dunaliella tertiolecta, are given for several combinations of light intensity and temperature, and for another species, Ditylum brightwellii, grown in nitrogen deficiency.The problem of estimating growth rates of phytoplankton was divided into three parts: 1) variation of growth rate among diverse species and its relationship to light absorption by cell chlorophyll a: 2) variation in growth rate with light intensity; 3) variation in growth rate with temperature. An equation has been formulated for calculating growth rate which provides a more precise fit of the data than do equations for growth rate based upon cell surface/volume ratios or cell volume. The formulation is based upon light absorption by chlorophyll a. It allows for variations in the efficiency of utilization of light absorbed by chlorophyll a and the changes in chlorophyll a content resulting from light intensity and temperature differences. We do not attempt to predict variations in growth rate with photoperiod or spectral distribution, nor do we allow for light effects upon growth rate not mediated by photosynthesis, so the model is, at best, a rough approximation of reality.
Chlorophyll Formation in Excised Roots of Cucumber and Pea
Authors: Björn L. O. , Odhelius Ingegerd 
Published: April 2006

AbstractThe effects of red and blue light on the formation of chlorophyll in excised roots of cucumber and pea was investigated and compared with previously reported experiments on wheat roots. All three kinds of roots are similar in that in continuous red light no or very little chlorophyll is formed. and in blue light a considerable amount of chlorophyll is produced. Roots of cucumber and pea differ from those of wheat, in that red light is ineffective (or nearly so) even when combined with blue.
Studies on the Fat Metabolism of Light‐ and Dark‐Germinated Seeds of Scots Pine (Pinus silvestris L.)
Authors: Nyman Bengt 
Published: April 2006

AbstractThe aim of the present investigation has been to study whether the light factor influences the fat metabolism in the scots pine seeds in any way which could be correlated with its effect on the germination. The studies have been made on petroleum ether extracts. Gravimetric determinations showed small increases of extractable material during the first 24 hours of the germination process. After a longer time there was a small but insignificant consumption (72 hours). No effects of the light factor could be found. Investigations with gas‐liquid chromatography on the corresponding extracts did not reveal any influence on the fatty acid composition, either of the light factor or of the germination period. The main identified fatty acids were linoleic, oleic, palmitic and stearic acid. One of the unidentified components (“c”) was also present in a large amount. Principally the same acids were found as free fatty acids but in different proportions: oleic, palmitic, linoleic and stearic acid. After the onset of the imbibition the linoleic acid appeared in the largest proportion. The total content of free fatty acids increased with increasing germination period. This was found both in titration experiments and in gas‐liquid chromatography with an internal standard. The latter method permitted studies on the content of the individual acids. During the period 0–21 hours there were no evident differences between the content in light‐ and dark‐germinated seeds, during the period up till 48 hours there was lower content in the light‐germinated seeds concomitant with the onset of the mitotic activity in these seeds and after 48 hours there was a rapid increase in the same ones corresponding to the opening of the seed coats and the incipient protrusion of the rootlets. Thus changes of free fatty acid content were found only after the start of the light‐induced growth but not under the preliminary phase, which earlier has been shown to be the determinative one in the light control of the germination.
Light‐controlled Cycocel Reversal of Coumarin Inhibition of Lettuce Seed Germination and Root Growth
Authors: Khan A. A. , Tolbert N. E. 
Published: April 2006

AbstractLettuce seed germination or lettuce root elongation after germination in water was inhibited by coumarin and these inhibitions were reversed by Cycocel. 2.53 × 103 M Cycocel reversed the inhibition of seed germination by 6.8 × 104 M coumarin. and 6.32 × lO−4 M Cycocel reversed the inhibition of root elongation by 3.4 × 103 M coumarin. No other analogs of Cycocel reversed these coumarin induced inhibitions of growth. Cycocel reversal of coumarin inhibition of lettuce seed germination occurred in red light but not in far‐red light or darkness. The red‐far‐red system was photoreversible. Cycocel and kinetin appear to act similarly in reversing coumarin inhibition of germination. Gibberellin A3 and IAA were unable to reverse these coumarin induced inhibitions. A common mechanism is suggested for Cycocel reversal of coumarin and lAA inhibition of growth.
Inhibition of Lettuce Seed Germination and Root Elongation by Derivatives of Auxin and Reversal by Derivatives of Cycocel
Authors: Khan A. A. , Tolbert N. E. 
Published: April 2006

AbstractLettuce seed germination or lettuce root elongation after germination in water was inhibited by 5.7 × 10‐6M indoleacetic acid (IAA) and designated other IAA derivatives. These IAA‐inhibited growth responses were reversed by 10‐5 to 10‐6M Cycocel, (2‐chloroethyl) trimethylammonium chloride, which alone was without effect. Only those Cycocel analogs, which have previously been shown to be active as plant growth retardants, were effective in reversing IAA inhibition of germination or root elongation. These results are consistent with the concept that Cycocel at low concentrations acts as an auxin antagonist. However. Cycocel did not reverse the inhibitory effects from indole‐3‐propionic acid or indole‐3‐butyric acid.
On the Reversal of the Inhibition of Photosynthesis Induced by Sodium Dimethyldithiocarbamate and Tetramethylthiuram disulphide
Authors: Lindahl P. E. Börn 
Published: April 2006

AbstractThe reversal of 80–100 per cent inhibition of photosynthesis in the green alga Enteromorpha linza (L.) J. Ag., obtained with tetramethylthiuram disulphide (TMTD) and the corresponding sodium dithiocarhamate (Na‐DMDT), was investigated. The inhibition obtained by the two compounds proves to be almost completely reversible by simply washing away the inhibitors. Copper(II) sulphate partially reversed the inhibition obtained with Na‐DMDT while reduced glutathione (GSH) partially reversed inhibition obtained with both Na‐DMDT and TMTD. The time to complete the reversal varied between 12 and 33 min. Almost no reversal of the TMTD induced inhibition was achieved with CuSO4.Na‐DMDT and CuSO4 reacted instantaneously with each other. GSH most probably reduced TMTD stoichiometrically to DMDT. This reaction was complete‐ within 6 seconds. No reaction took place between GSH and Na‐DMDT.The interpretation of The results eliminates the most conventional explanation of the mechanism of the inhibition of photosynthesis in E. linza with Na‐DMDT, viz. complex formation with functional metals. The reaction between TMTD and functional thiol groups in the alga is the most plausible inhibition mechanism. It is inferred from the results that Na‐DMDT is most probably oxidized by E. linza to TMTD and effects inhibition in this form. (PDF DAMAGE)
Excised Tobacco Pith Bioassays for Root‐knot Nematode‐produced Plant Growth Substances
Authors: Sandstedt Robert , Schuster Max L. 
Published: April 2006

AbstractRoot‐knot nematodes, Meloidogyne incognita, were grown in tobacco pith tissue cultured in vitro on modifired white's medium. The nematodes did not secrete detectable amounts of auxin or cytokinin, but did promote growth in the presence of both types of growth substance. When both IAA and kinetin were supplied, the nematode‐infected tissue was larger, more irregularly shaped than control tissue; nematodes induced syncytia and developed past the second larval stage. When either IAA or kinetin was omitted from the medium, nematodeinfected and control tissue failed to grow and the nematodes failed to induce syncytia or develop.
Temperature Fluctuation in Wintering Trees
Authors: Sakai A. 
Published: April 2006

AbstractTo investigate the mechanism of frost damage in trees, the temperature fluctualions in the stems and leaves of some wintering trees were recorded with copperconstantan thermocouples.In Sapporo, even the trunk of large elm trees with diameter of 86 cm are frozen during the winter. In a Kalopanax trunk with a diameter of 13.5 cm, the bark temperature on the south side which is exposed to direct sunshine reaches nearly 20°C about midday in midwinter; while, on the north side, the temperature remains nearly the same as the environmental temperature (0 to ‐5°C). The rise in the bark temperature in trees is considerably affected by factors such as the intensity of sunshine, the environmental temperature, the diameter of the trunk, the side of the trunk which the bark is on, the height above the ground, and the colour of the bark surface, etc. This rise is far less in small twigs, slender stems, and small leaves than in large ones. The south side of the bark 10 to 15 cm above the snow surface or above the ground in a slender stem is exposed to a remarkable fluctuation in temperature, especially when the ground is covered with snow.Even in northern trees, the cortical cells on the south side of trunks and twigs are less resistant to freezing than those on the north.
Light‐Inhibited Leaf Development in a White Mutant: Resemblance to Effeets of 2‐Thiouracil in Normally Pigmented Helianthus annuus
Authors: Habermann Helen M. 
Published: April 2006

AbstractWhen the white mutant of Helianthus animus is grown in full sunlight, leaf expansion and differentiation of the mesophyll are inhibited.More normal development results when incident wavelengths, shorter than 450nm, are removed by appropriate filters.A short wavelength photoreaction has been proposed which results in cessation of leaf development at a juvenile stage, and is analogous in its mechanism to the effects of 2‐thiouracil on leaf developmient.
Effects of Phenylethyl Alcohol on Chlorella pyrenoidosa
Authors: Knutsen Gjert 
Published: April 2006

AbstractAsynchronous as well as synchronous cultures were used to study the effect of phenylethyl alcohol on Chlorella pyrenoidosa. The following observations were made:

Autotrophic growth and the synthesis of DNA and chlorophyll were inhibited more than 80% by 8.4 mM phenylethyl alcohol when added to synchronous suspensions containing autospores.
Autospore formation did not occur when fully grown cells capable of division were transferred to 4.2 mM phenylethyl alcohol.
Photosynthetic oxygen evolution of asynchronous cultures was inhibited more than 70 % by 21 mM phenylethyl alcohol.
Endogenous respiration in the dark was stimulated by 8.4 mM, while higher concentrations were inhibitory.
Glucose respiration in the dark was inhibited by all concentrations in the range from 8.4 mM to 21 mM. Assimilation of glucose in darkness was retarded by phenylethyl alcohol at concentrations which gave maximal stimulation of endogenous respiration.

It is concluded that phenylethyl alcohol is not a specific inhibitor of DNA synthesis. The prime effect appears to be on respiration and photosynthesis.
Changes in Growth, Auxin‐ and Ribonucleic Acid Metabolism in Wheat Coleoptile Sections Following Pulse Treatment with Indole‐3‐Acetic Acid
Authors: Truelsen T. A. , Galston A. W. 
Published: April 2006

AbstractGrowth reactions of wbeat coleoptile sections following a brief pretreament in indole‐3‐acetic acid (LAA) were studied. The growth versus concentration curves 24 hours after the treatment showed a minimum value surrounded by bigber values. The minimum was never at concentrations lower than 10‐5M lAA but it could be found at higher concentrations after short pretreatment periods.The growth versus time curves reveated that the hormone treatment cansed the growth rate initially to increase but later on to decrease. The decrease was followed by a second increase for some treatments.Analysis of IAA content after the pretreatment showed that the attered growth patterns could be ascribed to declining auxin content with time, but not to thc actual concentration in the sections.The results indicate that the metabolic activation brought about by IAA leads to its own disappearance. Such a phenomenon was mirroretl in effects of IAA on hte net synthesis of ribonucleic acid.
Sources of Nitrogen for Spruce Tissue Cultures
Authors: White Philip R. , Gilbey Susan N. 
Published: April 2006

AbstractThe major heat‐labile organic ingredient of the nutrient previously developed in this laboratory for spruce cells is glutamine. This cannot be fully replaced by any single stable organic substance or group of substances tested. Its replacement by inorganic ammonium salts results in no significant reduction in growth rate in terms of wet weights but produces qualitative defects which make such sutistitutions undesirable. Of special interest is the production of reticulated xylem cells when cultures are grown in the light on NH4 supplements.
Aging and Mitochondrial Development in Potato Tuber Tissue
Authors: Lee S. G. , Chasson R. M. 
Published: April 2006

AbstractRespiratory activity of mitochondria isolated from fresh and aged potato tuber tissue has been determined. No significant change in activity of the particles (expressed per unit N) was observed as a result of aging. However, the yield of mitochondrial material increased with aging. It has been suggested that the commonly observed stimulation of respiration that accompanies aging of potato tissue can be attributed largely to an inerease in the mitochondrial population rather than to a stimulation of the particles per se, and that this increase results from a fission of pre‐existing mitochondria.The respiratory activity of mitochondria isolated from unaged tissue was found to decline following storage of the tubers in the cold for extended periods. This decline was attributed to a loss of cristae structure in the particles, as observed microscopically. The possibility that this reduction in structural organization might be associated with changes in the state of dormancy of the tissue was considered.
Root Nodule Symbiosis II
Authors: Silver W. S. , Bendana F. E. , Powell R. D. 
Published: April 2006

AbstractNodule‐roots of Myrica cerifera (Southern Wax Myrtle) and Casuarina cunning hamiana (Australian Pine) have a negative geotropic curvature. Studies of their endogenotts auxin content revealed a pattern of correlation: the absence of detectable auxin when the geotropisni was negative. Non‐nodulated roots of Myrica exhibited a normal positive geotropic curvature and possessed an auxin content within an anticipated range (10 mg/kg). Root nodules of Alnus species, whose roots exhibit a positive geotropic curvature, contained measurable endogenous auxin (20 mg IAA/kg).The presence of an indoleaectic acid oxidase system in Myrica and Casuarina root nodules has heen described and correlations are drawn between non‐detectable endogenous auxin concentrations and high enzymatic activities.It is suggested that the negative geotropic curvature of the nodule‐roots of Myrica and Casuarina is due to the presence of a sub‐optimal concentration of auxin which in turn results from the activity of an indoleacetic aeid destroying system.
Photosynthetic and Dark Fixation of 14CO2 in Detached Soybean Cotyledons
Authors: Abrahamsen Mary , Mayer A. M. 
Published: April 2006

AbstractDetached soybean cotyledons fixed CO2 both in the light and dark. Carbon dioxide fixed by the light and dark reactions replaced only a small portion of CO2 lost by respiration up to the 10th day. In the dark most of the 14C label was found in the acidic fraction, while in the light 65 per cent of the activity was found in the neutral and basic fractions.
Alterations in Amino Acid Content Caused by 3‐amino‐l,2,4‐triazole
Authors: McWhorter C. G. , Hilton J. L. 
Published: April 2006

AbstractChanges in the amino acid content of Zea mays and Sorghum hnlcpemr by treatments with amitrole (3‐amino‐l,2,4‐triazole) are reported. The evidence suggests that inhibition of histidine biosynthesis is probably not the mechanism of amitrole action in young seedling plants. Reductions in glycine and serine content of treated plants were observed. Results are discussed in relation to current theories on mechanisms of herbicide action.
Primary and Secondary Carotenoids of Spongiochloris typica
Authors: McLean Robert 
Published: April 2006

AbstractA qualitative and quantitative investigation was made of the pigments of Spongiochloris typica over an 8 week period. The pigments were chromatographed on thin layers of sucrose and measured spectrophotometrically. Pigments present after 1 week of growth were identified as chlorophylls a and b, β‐carotene, lutein, zeaxanthin, violaxanthin, trollein, and neoxanthin. In cultures 2 weeks or more old, secondary carotenoids appeared. These were echinenone, canthaxanthin, astacene, and an unidentified ketocarotenoid. Carotenoids comprised nearly 100 percent of the total pigment composition on the 8th week. About 75 percent of the carotenoid fraction on the 8th week consisted of secondary carotenoids.