bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phenylmereuric Acetate and Phosphate Control of Light‐Dependent Shrinkage and Reactions in Chloroplasts
Authors: Siegenthaler Paul André 
Published: April 2006

AbstractAn investigation of the action of phenylmereuric acetate (PMA) and phosphate on light‐induced shrinkage (measured by light scattering and Coulter Counter techniques) and on photosynthetic reactions in spinach chloroplasts led to the following conclusions:

PMA stimulated light‐induced shrinkage (under conditions of cyclic and non‐cyclic electron flow) at concentrations which completely inhibited cyclic and non‐cyclic photophosphorylation and nicotinamide adenine dinucleotide phosphate (NADP) reduction, though ferricyanide reduction was activated. Although PMA inhibited NADP reduction (probably because this sulfhydryl reagent interfered with the ferredoxin‐NADP rednetase) it ean also be considered an uncoiipler (when ferricyanide is the electron acceptor).
Phosphate maximized light‐induced shrinkage (under conditions of cyclic and non cyclic electron flow) at concentrations which did not affect ferricyanide reduction but caused a 40 to 50 per cent inhibition of NADP reduction.
The pattern of the light scattering response to these two compounds was quite different. In the presence of PMA, the forward (light on) and hack (light off) reactions went to completion rapidly. In the presence of phosphate, the back reaction was rapid but, in the light‐induced reaction, three phases were discernible.
Compared with uncouplers such as NH4Cl, carbonyl cyanide m‐chlorophenyl‐hydrazone, pentachlorophenol, and dicoumarol, all of which inhibited both photophosphorylation and conformational changes in chloroplasts, PMA (like quinacrine) had a specific action since it inhibited photophosphorylation while shrinkage was stimulated.
It appeared that PMA acted at a site beyond the formation of high energy inter‐mediates and that, in the absence of photophosphorylation, more energy was diverted to mechanical work (shrinkage). It would seem that, in a cyclic electron flow system, in which ATP synthesis is blocked at a late step (e.g. by PMA), shrinkage may be an indirect method for measuring electron flow.
Growth Substances Separated from the Fruits of Cassia fistula
Authors: Mukherjee R. K. , Bhanja Arati , Sircar S. M. 
Published: April 2006

AbstractThe growth substances of the seeds of Cassia fistula were studied and the changes in the relative levels in the endosperm and embryo (plus cotyledons) with development of the seed were noted.Indoleacetic acid was found to be the major auxin component of the seed almost throughout its growth and development, while acidic inhibitors possibly belonging to β‐complex were also noted in bioassay tests.The main source of the IAA in the seed is the endosperm, although measurable amounts are also present in the embryo. While this IAA activity in the endosperm is detectable till maturity of the fruit, it decreases relatively in the embryo to fall to insignificance at maturity of the seed. However, there is indication of the binding of such IAA in the embryo or the cotyledon, which can be released by alkaline hydrolysis but not before the seeds are matured. No such bound auxin could be detected in the endosperm. The inhibitors, on the other hand, are more prominent in the embryo than in the endosperm, particularly with ageing of the fruit. The possible significance of these changes in the growth factors has been discussed in relation to the age of the seed and the development of the embryo inside it.
Quantitative Determinations of the Effect of Excision on Transpiration
Authors: Falk Stig Olof 
Published: April 2006

AbstractThe temporary transpiration increase which normally occurs when a shoot or a part of a shoot is cut off in the air was studied qnantitatively in young wheat plants by the aid of the corona‐hygrometer.The temporary transpiration increase can be characterized by the maximum increase in transpiration rate after the cutting, or by the total time of the temporary transpiration increase, or by the quantity of water given off by the shoot due to the temporary transpiration increase.The influences of the water vapour pressure, the speed of the air stream, and the light intensity on the temporary transpiration increase were determined. It is important to pay attention to the climate in the chamber where the shoot transpires.The maximum temporary transpiration increase was reduced more or less lineary with increasing water vaponr pressure of the air surrounding the shoot and increased with increasing speed of the air stream through the transpiration chamber. The reduction of the maximum temporary transpiration increase at higher light intensities was mainly due to the higher water vapour pressure in the chamber.The total time of the temporary transpiration increase was very little influenced by the water vapour pressure but was reduced more or less lineary with the logarithm of increasing light intensity.When the shoot was cut off in the water, there was normally no temporary transpiration increase. Only at low light intensities there could occur temporary transpiration increases similar to those found when the shoot was cut off in the air.Some hypotheses which could explain the temporary transpiration increase are discussed. The results in this investigation seem to favour the hypothesis that the temporary transpiration increase is due to a sudden reduced water transport up into the leaf, which can bring about a passive opening of the stomata.
Action Spectra of Photosynthetic Activities of Chlorella ellipsoidea
Authors: Lundegådh H. 
Published: April 2006

Abstract

Suspensions of Chlorella show an even stronger light scattering than suspensions of chloroplasts of spinach. The bands of absorption are thus broadened and, at higher concentrations, moved to lower wave‐lengths. The intensity of the photosynthesis closely follows the curves of light scattering, a fact partly explaining the high efficiency of green light. Calculated per unit thermoelectrically measured incident energy the action spectrum shows bands at 660–670 nm and c. 500 nm and a comparatively high level of the whole region 500–560 nm.
Flash experiments show the existence of a steady state carotene/xanthophyll that is moved to reduction (c/x > 1) in blue and green light and to oxidation (c/x < 1) in red light. All experiments point to the existence of two light reactions, the first one involving excitation of carotenoids, with ferredoxin‐TPN as acceptor, the second one involving excitation of chlorophyll, with the cytochrome system of the chloroplasts acting as donors of electrons and thus completing an energy converting circulation between pigments and enzyme systems.
The operation of combined light reactions appears also from experiments with simultaneous or succedaneous illumination with monochromatic light of different wave‐lengths. Some effects may be explained from separate excitations of carotenoids and chlorophylls, others may depend on still unknown photic reactions.
The action spectrum in ultrared shows a positive band at c. 900 nm but no or only very small effects in the region 950–1400 nm. Ultrared radiation has on the other hand an enhancing effect on the light excitation in the visible spectrum. A combination of infrared and visible radiation shows a roughly linear relation between incident energy and photosynthetic effect.
All experiments were performed in the region of linear relation between intensity of incident light and O2‐production. Induced effects of combined monochromatic regions show a very rapid initial change in the steady states that in one or two minutes simmers down to a balanced state of continued photosynthesis. No change was observed in the total quantity of the pigments.
Absorption and Transport of Sulfate by Wheat at Varying Mannitol Concentration in the Medium
Authors: Ingelsten Birger 
Published: April 2006

AbstractUptake and transport of sulfate labelled with 35S have been determined in wheat at varying mannitol concentration in the medium.The magnitude of the apparent free space (AFS) of the roots from decapitated plants was constant up to incipient plasmolysis where the AFS values increased abruptly due to the entrance of the medium into the cell lumen.The sulfate retention of the roots from decapitated plants and from intact plants at a low water uptake increased at non‐plasmolysing mannitol concentrations but fell abruptly at plasmolysis. The retention including the increase at mannitol addition seemed to be effected by an active process.The sulfate transport to the shoot was also increased at a low, practically constant water uptake at the addition of non‐plasmolysing mannitol concentrations. At transpiration‐stimulating conditions the sulfate transport was almost constant while the water uptake was sinking. This apparent constancy depended on a composed effect of the mannitol addition. A non‐plasmolysing concentration in itself tended to increase the sulfate transport and the simultaneously lowered water uptake diminished it.The increase of the sulfate transport to the shoot before plasmolysis in the root seemed to involve stimulation of an active process. A passive mass flow directly from the medium to the shoot could be shown to occur only at a very limited extent or not at all. The concentration of such a flow as compared with unity concentration of the medium was calculated to be maximally 0.03.After plasmolysis in the root the transport seemed to be entirely a mass flow indicating that a diffusion barrier could now be passed by the sulfate. Endodermis is suggested to be this barrier. The concentration of the mass flow was lower than the medium concentration indicating that the endodermis was only partly broken.The effect of a non‐plasmolysing mannitol concentration increasing both the sulfate retention of the root and the sulfate transfer to the shoot cannot be explained but some possibilities are discussed. An explanation by a structural change of the free space is favoured.
Effect on Transpiration and Water Uptake by Rapid Changes in the Osmotic Potential of the Nutrient Solution
Authors: Falk Stig Olof 
Published: April 2006

AbstractThe sudden changes in the rates of transpiration and water uptake which occurred when the osmotic potential of the nutrient solution surrounding the roots of young wheat plants was rapidly changed were studied. The transpiration was measured by the aid of the microwave hygrometer and the water uptake by a recording poto‐meter specially built for this investigation.When the osmotic potential of the nutrient solution was rapidly increased by adding mannitol, there was a temporary transpiration increase. The maximum increase was greater but the total time of the temporary increase shorter when a higher mannitol concentration was used. The quantity of water transpired by the shoots due to the temporary transpiration increase seemed to be fairly constant irrespectively of the mannitol concentration. The water transport to the shoots was immediately reduced when the osmotic potential was rapidly increased. The immediate reduction was greater when a higher mannitol concentration was used. After the immediate reduction the rate of water transport increased without delay.When the osmotic potential of the nutrient solution was rapidly decreased by withdrawing mannitol there was a temporary transpiration decrease, and the water transport to the shoots was immediately increased. After this increase the rate of water transport started to decrease at once. When, however, the mannitol concentration had been 0.30Mor higher, the transpiration rate increased progressively, and the change of the rate of water transport was small.The results indicate that the primary effect of the rapidly changed osmotic potential is localized to the root surface. The rapidly reduced water transport to the shoots after adding mannitol brings about the temporary transpiration increase. The course of events after withdrawing mannitol is just the reverse to that when adding mannitol.
The Effect of 2,4‐Dinitrophenol on Translocation in the Phloem
Authors: Harel Shulamith , Reinhold Leonora 
Published: April 2006

AbstractThe effect of 2,4‐dinitrophenol (DNP) on sucrose‐14C transport in Soya seedlings has been analysed. The aim was to distinguish between an effect of the inhibitor on sugar movement within the phloem sieve tubes themselves, and on the prior steps of uptake and secretion of sugar into the conducting cells.DNP drastically inhibited sucrose‐14C transport if it was applied to the 14C‐treated leaf immediately before, or during, 14C supply. Transport was also strongly inhibited if DNP was applied along the translocation path while the 14C‐treated leaflet was still in position on the plant. When, bowever, DNP was applied through the cut petioles of the primary leaves after removal of the 14C‐treated terminal leaflet of the first trifoliate leaf, no inbibition was observed. On the contrary, transport appeared to have been promoted: significantly more 14C disappeared from the upper regions of DNP‐treated plants as compared with controls, while in the lower plant parts more 14C accumulated. Different rates of synthesis of sucrose‐14C into non‐alcohol‐soluble compounds could not account for this result. A similar stimulatory effect was observed when DNP was applied to the cut petiole of a primary leaf opposite that treated with 14C.Several indications were obtained that 14C which has reached the lower parts of the plant may circulate upwards again through the phloem within about 15 minutes. When sucrose‐14C was introduced into the roots via the xylem, both DNP treatment and prior steam girdling resulted in the apparent accumulation of 14C in the lower plant parts. the results would be compatible with DNP inhibition of upwards movement in the phloem. DNP might also have affected sugar uptake processes in cells neighbouring the translocation path.It is concluded that the inhibitory effect of DNP on downwards phloem transport reported by earlier workers was probably due to an effect on uptake and/or secretion into the sieve tubes, not to an effect on the conducting cells themselves. Modern theories for phloem transport are discussed in the light of these findings.
The Role of Light in Leaf and Flower Bud Break of the Peach (Prunus persica)
Authors: Erez A. , Samish R. M. , Lavee S. 
Published: April 2006

AbstractThe effect of light on peach leaf and flower bud break was examined. It was found that leafless dormant shoots were light‐perceptive organs. Darkness, after light preconditioning during dormancy, reduced leaf bud opening; however, light was obligatory when the shoots were preconditioned in the dark. Relatively short exposures to light were sufficient to stimulate leaf bud break. Terminal buds were less inhibited by darkness than were laterals. Flower bud break was inhibited in light after dark preconditioning. The red region of the spectrum was found to be active; the phytochorome system seems to be involved in the light reactions, as the red light effect was reversible with subsequent far‐red illumination. Supplementary light, producing long‐day conditions, could partly compensate for insufficient chilling. A possible sequence of reactions in the plant is suggested.
Effects of Hydroxybenzoic Acids on Oxidation of Reduced Nicotinamide Adenine Dinucleotide by Enzymes from Tobacco Leaves
Authors: Lee T. T. 
Published: April 2006

AbstractHydroxyhenzoic acids were tested for their effects on oxidation of the reduced nicotinamide adenine dinucleotide (NADH) in the absence of added H2O2 and Mn2* by an enzyme preparation from tobacco leaves (Nicotiana tabacum, var. White Gold). For comparison, a commercial horseradish peroxidase was also used. The rate of NADH oxidation was followed spectruphotometrically at 340 nm.Mono‐ and dihydroxybenzoic acids exerted significant effect on the rate of NADU oxidation, yet their effectiveness was determined by the number and position of the hydroxyl group on the ring. 4‐Hydroxybenzoic acid was very effective in stimulating the reaction. Shifting the hydroxyl from the 4‐ to the 3‐position and from the 3‐ to the 2‐position decreased activity. 2,4‐ And 2,5‐dihydroxybenzoic aeids were more active than the other dihydroxy‐iscuners in stinulating oxidation of NADH. the dihydroxybenzoic acids with the hydroxyls in adjacent positions were less effective, and their activity was affected by other phenolic activators. In the presence of 4‐hydroxybenzoic acid which enhanced oxidation of NADH, 2,4‐ and 2,5‐dihydroxybenzoic acids further stimulated the reaction, but 3,4‐, 2,3‐ and 2,6‐dibydoxybenzoic acids were inhibitory. The inhibition by 3,4‐ and 2,3‐dihydroxybenzoic aciils was non‐competitive.The enzymes extracted by a L‐cysteine‐containing buffer showed lower NADH‐oxidase activity.The enzyme preparation possessed peroxidase activity. The activity of NADH‐oxidase inereased when H2O2 and Mi2* were present in addition to 4‐hydroxy‐benzoic acid. The effect of the position and number of hydroxyl substitution on the rate of NADH oxidation by borseradish peroxidase was also significant. This suggests the involvement of peroxidase in the NADH‐oxidase system of tobacco leaves. However, a combination of the inactivated enzyme solution and active horseradish peroxidase with peroxidase activity equivalent to that of the enzyme preparation from tobacco leaves did not reconstitute the NADH‐oxidase activity of tobacco leaves. This and other evidence suggests that the soluble NADH‐oxidizing zyme system of tobacco leaves is more complicated than peroxidase.
The Intercellular Spaces of the Avena Coleoptile
Authors: Sorokin Helen P. 
Published: April 2006

AbstractIn the transverse sections of fresh Avena coleoptile certain intercellular spaces are transparent, others are dark. The transparent spaces represent the result of water‐logging of the originally water‐lined air passages. The dark spaces are lined with a plastic lipid‐containing membrane which can be impregnated with melted paraffin. In the living tissue this membrane can be cut transversely and the cut sections presumably seal off the gas inside thus causing the dark interfacial refraction. Because of the high permeability of lipids to carbon dioxide and the virtual impermeability to oxygen and nitrogen, there is a reason to believe that the lipid‐lined spaces are filled with gas rich in carbon dioxide, and the lipid membrane may function as a regulator of the diffusion pressure of this gas.
Mannitol Production by Pyrenochaeta terrestris
Authors: Wright James R. , Le Tourneau Duane 
Published: April 2006

Abstract Pyrenochaeta terrestris (Hansen) Gorenz, J. C. Walker and Larson produces D‐mannitol in the mycelium but not in the cutture filtrates when grown in a sucrose salts liquid medium.In the present study, P. terrestris was grown in stilt culture on a synthetic salts medium containing 30 g of sucrose per liter. After inoculation with a myceliat suspension, the mycelial mats were harvested and the dry weight and the amount of mannitol were determined. Maximum mycelial mat production occurred at 15 days after inoculation while the amount of mannitol was greatest at about 7 days after inoculation. The percentage of mannitot on a dry weight basis was maximal (20–25 per cent) within a few days after inoculation and decreased rapidly to 3–4 per cent at the time mycelial mat production was greatest. The same percentage of mannitot was produced when the fungus was grown in shake culture or when the sucrose was replaced by equivalent amounts of D‐fructose, D‐glucose, D‐mannose, maltose, trehalose, and raffinose. Increasing the amount of sucrose or decreasing the amount of sodium nitrate increased the amount of mycelium produced but the percentage of mannitol in the mycelium remained about the same.Mannitot was reutilized when mycelial mats were transferred to a mineral medium without a carbon source. It was concluded that mannitot probably serves as a reserve carbohydrate in P. terrestris.
A Comparison between the Cellulolytic Activity of White and Brown Rot Fungi. I. The Activity on Insoluble Cellulose
Authors: Johansson Martin 
Published: April 2006

AbstractAbout 70 strains of white and brown rot fungi were cultivated on media, containing filter paper cellulose as the main carbon source. The cellulolytic activity of the culture filtrates was measured after different periods of growth by means of the turbidimetric method. The results obtained indicate a difference between the two types of wood decay fungi as to the capacity of attacking the cellulose used in the medium and in the cellulase test. No significant C1activity was found in any of the brown rot cultures whereas all white rot fungi tested exerted a measurable activity on the test substrate.The effect of various carbohydrates and some proteins as inducers of cellulase activity was studied. Especially cellobiose and lactose were active on white rot fungi in this respect, particularly in the presence of yeast extract. Also some brown rot fungi exerted C1‐activity after incubation on glucose or cellobiose.
Interaction of Kinetin and Various Inhibitors in the Growth of Soybean Tissue
Authors: Blaydes David F. 
Published: April 2006

AbstractThe growth of kinetin‐requiring soybean callus was inhibited by the purine analogs 2,6‐diaminopnrine, 8‐azaguanine and 8‐azaadenine. The purine analog 6‐mercaptopnrine and the antibiotic puromycin were not effective as inhibitors at the concentrations employed. Reversal of the inhibition was attempted by raising the kinetin concentration. Kinetin did not reverse the inhibition due to 2,6‐dianiinopurine but it did lessen to some extent the inhibition due to 8‐azagnanine. It is suggested the kinetin affects RNA metabolism.
Action Spectra and the Role of Carotenoids in Photosynthesis
Authors: Lundegårdh H. 
Published: April 2006

AbstractThe action spectrum of photosynthetic (Vprochtetion was determined with ehloro‐plast suspensions and whole leaves. Owing to a dominating influence of light scattering the action spectrum shows a much more uniform absorption of the incident light than would be expected from the absorption spectrum in direct light (0° deviation).The comparatively strong photosynthesis in green is probably further aided by the light reaction between cytochrome f and chlorophyll in which also the cyto‐chromes act as pigments.The whole region 400 to about 900 mn is photosynthetically active with an obvious tendency to linear relation between the intensity of incident radiation ami photosynthetic Co‐production, certain deviations hereby caused by specific absorption or activation.The results illustrate the participation of carotenoids in the primary energy conversion of photons to activated electrons and the role of at least two light reactions in the photosynthetic cycle.The reducing power of illuminated (3‐carotene was demonstrated in vitro in its effect on ferredoxin. The steady state situation of pigments and enzymes is discussed.
Action Spectrum of Coccolith Formation
Authors: Paasche E. 
Published: April 2006

AbstractThe action spectrum of coccolith formation in Coccolithus huxleyi was determined by measuring the uptake of carbon‐14 in coccoliths in four‐hour experiments as a function of light intensity at each of seven wavelengths. An action spectrum | of photosynthetic carbon assimilation was obtained at the same time. The coccolith action spectrum had peaks at wavelengths of about 440 nm and 670 nm. probably corresponding to the regions of maximum cellular absorption and carbon assimilation. However, blue light appeared to be relatively more efficient in coccolith formation than in carbon assimilation.The results suggest that light‐dependent coccolith formation may be catalyzed by two photochemical reactions, one mediated by chloroplast pigments and the other by some pigment absorbing specifically in the blue part of the spectrum.