bluuebunny/crossref_metadata_2025 huggingface dataset:
Protochlorophyll/Chlorophyll Conversion by Single Flash Illumination
Authors: Madsen Axel
Published: April 2006

Previous studies (Smith and Benitez 1954) have shown the rate of the photochemical conversion of protochlorophyll to chlorophyil‐a in etiolated leaves to be proportional to the product of the light intensity used and the duration of the illumination.

This relation, however, is considered to be valid only in the case of moderate light intensities and relatively short periods of illumination. Thus Koski (1950) found a reduction of the total content of pigments in etiolated corn leaves following 180 sec illumination of 150 fc (approximately 1600 lux); she considered this to be a destructive effect of the light. Virgin (1955) found a considerable destruction of chlorophyll to take place in etiolated barley leaves during illumination with 600 fc (about 6500 lux).

In the present paper it is shown that by using very high light intensities and very short periods of illumination it is possible to transform approximately 40 percent of the protochlorophyll of etiolated wheat leaves to chlorophyll‐a without effecting any light induced loss of the total content of pigments.
p‐Hydroxybenzoic Acid, a Growth Regulator, Isolated from Woody Cuttings of Ribes rubrum
Authors: Vieitez E. , Seoame E. , Gesto D. V. , Mato C. , Vazquez A. , Carnicer A.
Published: April 2006

Woody cuttings of Ribes rubrum, an easy plant to root, were extracted with methanol. One fraction of this extract was both water and ether soluble; a part of it was only water soluble. From the water and ether soluble fraction a crystalline compound was isolated which was fully identified with p‐hydroxybenzoic acid (PHB) by m.p., mixed m.p., infrared spectrum, ultraviolet absorption in neutral and alkaline methanol and chemical analyses.

For Avena coleoptiles straight growth test, p‐hydroxyhenzoic acid was found to have a significant growth promoting activity in the range 20–100 μg/ml. and it showed strong growth inhibition at concentrations higher than 200 μg/ml.

From the same extract fraction a phenolic ester was isolated by paper chromatography which showed a weak growth inhibiting activity. This compound was identified as an ester of p‐hydroxybenzoic acid by micro‐scale reactions.

From the extract soluble only in water further amounts of crystalline p‐hydroxybenzoic acid were obtained by alkaline hydrolysis. This PHB may have arisen from the breakdown of pelargonidin glucosides.
Stomatal Opening as a Practical Indicator of Moisture Stress in Cotton
Authors: Alvim Paulo de T.
Published: April 2006

The response of stomata to varying soil moisture content was studied in cotton by means of a new type of porometer suitable for field work. The results showed that maximum stomatal aperture was only attained when soil moisture was near the upper limit of the so called “available range”. These results indicate the possibility of making practical use of the new type of porometer for the purpose of determining soil moisture deficiency under field conditions, thus aiding in irrigation practices.
The in vitro Germination of Pollen of Setaria sphacelata 2. Relationships between Boron and Certain Cations
Authors: De Bruyn J. A.
Published: April 2006

The effects of different calcium levels upon germination and tube growth of the pollen of Setaria sphacelata (Schum.) Stapf and Hubbard were studied at low, optimal and high levels of boron. Calcium (10 and 100 mg/1) stimulated germination at all levels of boron and enhanced tube growth to an even greater degree. The inhibitory effects of high boron levels (50 mg/1) were largely overcome by addition of 10 to 100 mg/1 calcium. Magnesium (1 and 10 mg/1) stimulated germination and tube growth at optimal and high boron levels, but 100 mg/1 magnesium were highly inhibitory. Potassium and sodium had little effect upon pollen germination or tube growth at any level of boron supply. It was concluded that calcium, together with sucrose and borate, might be required for optimal germination and growth of the pollen tubes. Nevertheless, the tubes obtained were much shorter than required for fertilisation in vivo, indicating either that some essential factor was still missing or that the pollen is inherently incapable of producing tubes of adequate length.I wish to thank dr. Donald T. Krizek for critically reading the manuscript.
Enhancement of Enzymatic Synthesis of Citrate in vitro by Indole‐3‐Acetic Acid
Authors: Sarkissian Igor V.
Published: April 2006

Indoleacetic acid in physiological concentrations was shown to enhance the synthesis of citiate by purified citrate condensing enzyme from castor beans and pig heart. Michaelis constants reveal that with indoleacetic acid in the reaction mixture a higher concentration of acetyl‐CoA was necessary to give maximal velocity. V values with indoleacetic acid in the reaction (physiological concentrations) exceeded V without indoleacetic acid in reaction. Citric acid synthesized from 14C acetyl CoA was highly radioactive when indoleacetie acid was present in the reaction, indicating that indoleacetic acid did in fact enhance the synthesis. The data were discussed from the point of view that these studies may provide the basis for studies directed at ultimate understanding of the mechanism of action of indoleacetic acid.
The Deciduous Behavior of a Tropical Plant, Plumeria acuminata
Authors: Murashige Toshio
Published: April 2006

The deciduous behavior of the tropical perennial Plumeria acuminata Ait., cultivar Sherman White, was investigated. The temperature during the period of experiment varied only 3°C, the mean maxima and minima, respectively, being; 28.5° and 23.5°C for summer months and 25.5° and 20.6°C for winter months. The length of the day‐light period ranged from 14¼ hours on the longest day in June to 11¾ hours on the shortest day in December.

Under naturally prevailing conditions of temperature and day‐lengths, cessation of leaf formation and shedding of foliage occurred during the longer‐night, autumn‐winter months. The shedding was manifested in two stages: from mid‐October to mid‐January there was a slow but steady decrease in the number of leaves per plant, and in late January there occurred an abrupt abscission of all remaining leaves. Light interruptions during the middle of each night prevented a net loss in foliage as well as the en masse shedding in late January.

Stem elongation was retarded during the autumn‐winter months, but its rate was fully restored when the long nights were interrupted with artificial light. Flowering was unaffected by day‐length.

On the basis of these observations it is concluded that the deciduous behavior of Plumeria and perhaps other tropicals, alike temperate climate species, is governed by photoperiod. Cessation of leaf formation and en masse shedding of foliage are induced by long nights. However, in contrast to temperate zone plants, in which deciduousness is an adaptation against the winter cold and freeze, deciduousness provides tropical plants a survival advantage, perhaps, against seasonally recurring droughts.
The Effect of Nouaual on Dipodascus aggregatus
Authors: Nyman Brita
Published: April 2006

The growth of a strain of Dipodascus aggrrgatus Francke‐Grosmann was strongly promoted by the aliphatic aldehyde nonanal. The highest effect was found with 80–160 μmol of nonanal per 1.

The growth‐promoting activity of nonanal is principally the result of an ability to shorten the lag phase. Neither the maximum value for growth nor the growth rate seem to be increased.

The growth‐promoting activity of nonanal could be observed only if the cells used for inoculation were taken from a culture in the phase of accelerated growth.

The highest growth‐promoting activity was observed when the nonanal was added before inoculation, a large effect was still observed when it was added 24 hours after inoculation, but there was no effect when it was added 33 hours after inoculation.

The growth‐promoting activity of nonanal remained unchanged when a mixture of 15 vitamins and growth factors was given to the medium.

Nonanol and nonanoic acid stimulated growth, although to a lower degree than nonanal.

There was a gradual increase in the growth‐promoting effect of nonanal as the pH of the medium was increased between 3.0 and 8.0, showing that this effect is most pronounced at the higher pH values.
The Effect of Nutritional Factors and Certain Growth Substances on the Growth of Disks Cut from Young Leaves of Phaseolus
Authors: Dale J. E.
Published: April 2006

The roles of some chemical factors influencing leaf expansion were investigated using disks cut from the primary leaves of young plants of Phaseolus grown in subdued light. Mineral nutrients, cobalt, sucrose, GA and IAA or NAA at suitable concentrations all caused increases in fresh and dry weights of such disks. When all these substances were applied together the increases in diameter and in fresh and dry weight and cell number were very large and comparable with the rates found in intact leaf tissue. The response of disks to sucrose was found to be light dependent, and a number of other significant interactions were noted. Disks cut from older leaves, in which cell division had ceased, did not show large increases in fresh weight in response to treatment with sucrose, and in this such disks differ from those cut from leaves in which cell divisions are continuing. The possible significance of this is discussed and the roles of light and the other chemical factors investigated are assessed in terms of influence on cell division and expansion in disk tissue.
The Interaction of (2‐Chloroethyl) trimethylammonium Chloride and Gibberellic Acid in Strawberry
Authors: Guttridge G. G.
Published: April 2006

Applications of (2‐chloroethyl) trimethylammonium chloride (CCC), by foliar spray or to the soil, shortened petioles and decreased top and root growth of strawberry plants. Application of gibberellic acid increased petiole length and fresh weights of tops but not of roots. Applied together gibberellic acid overcame the depression of growth in weight of tops induced by CCC and countered the depression in petiole lengths. Gibberellic acid induced elongation of internodes of the vegetative stem and the elongation was increased substantially by concurrent application of CCC.

This synergism in stem growth indicates a lack of antagonism between CCC and exogenous gibberellic acid in strawberry. The implications are discussed.
Effect of Temperature on Germination of Spores from Some Bacillus and Clostridium Species
Authors: Lundgren Lillian
Published: April 2006

The effect of temperature on germination of spores of Bacillus subyilis, B. megaterium. B. cereus, Clostridium sporogenes, Cl. butyricum and Cl. bifermentans was studied.

At lower temperatures (+5°C to +10°C) the three Glostridium species germinated to a less extent than the three Bacillus. species.

The optimum temperature for germination of the six species varied between +35°C and +45°C.

The Clostridium species were more tolerant to heat than the Bacillus species.
The Effect of Simulated Caterpillar Damage on CO2 Fixation and Translocation in Banana Leaves
Authors: Johnson Barbara E. , Brun W. A.
Published: April 2006

A study was undertaken to see how a small hole in a leaf such as caused by a feeding caterpillar will influence photosynthesis and translocation in the remaining leaf tissue. Banana leaves were exposed to C14O2 at various intervals before and after holes were made in the leaves with a cork borer. Radioautographs were taken to study the extent of CO2 fixation and translocation.

Results show that photosynthesis is impaired for only 24 hours. Downward translocation is affected for 48 hours. Caterpillar damage of small areas does not seem to affect normal leaf functions beyond these time limits.
Non‐Enzymatic Reduction of Nitrite by Means of Ascorbic Acid in Citrus and Other Higher Plant Tissues
Authors: Bar‐Akiva A. , Sternbaum J.
Published: April 2006

It has been proved that the nitrite reduction in the leaves and other plant tissues of citrus and other green plants is partly or mainly a non‐enzymatic chemical process, and a heat‐stable factor present in these tissues is responsible for this reduction.

It is suggested that ascorbic acid plays a major role in this chemical reaction since the reduction is inhibited by ascorbic acid oxidase. A significant association was also found between the ascorbic acid content and the nitrite reduction capacity of citrus leaves.

Evidence has been presented that this non‐enzymatic chemical reduction of nitrite occurs also in vivo as undetached citrus leaves on branches placed in NaNO2 solution have shown diminution of their ascorbic acid content along with the absorption of nitrite. Stronger accumulation of nitrite in these leaf tissues was observed under dark conditions, apparently due to the inhibition of the biosynthesis of the ascorbic acid.
The Effect of Temperature and Light on the Germination of Lettuce Seeds
Authors: Berrie Alex. M. M.
Published: April 2006

‘Grand Rapids’ lettuce. seed will not germinate in darkness at 30°. An exposure in temperatures between 5°C and 25°C for a short period after the initiation of germination can effectively overcome the high temperature imposed dormancy. If the exposure to low temperature is from the beginning of germination it is less effective.

The low temperature induced germination is not reversed by far red light of 725 nm and seed not responding to the low temperature do respond in a classical fashion to red and far red irradiations.

It is considered that the results justify acceptance of the hypothesis that an inhibitor of germination is produced during the initial stages of germination and that this formation is strongly temperature dependent so that there is much accumulation. At low temperatures an alternative metabolic pathway predominates leading to the production of an essential metabolite. At high temperatures this metabolite is produced from the inhibitor (or inert compound) by a mechanism under the control of the phytochrome system.
Phenylmereuric Acetate and Phosphate Control of Light‐Dependent Shrinkage and Reactions in Chloroplasts
Authors: Siegenthaler Paul André
Published: April 2006

An 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

The 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

The 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

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

Uptake 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

The 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

The 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

The 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

Hydroxyhenzoic 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

In 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

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

About 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

The 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

The 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

The 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.
Photosynthetic Activity during the Life Cycle of Synchronous Skeletonema Cells
Authors: Jørgensen Erik G.
Published: April 2006

A culture of Skeletonema costatum grown at a light intensity of 3 klux and at 20°C was synchronized in diurnally intermittent illumination of 12 hour light and 12 hour dark. The culture was hardly fully synchronous as the cell division period lasted about 9 hours. The cell division started in the middle of the light period. The concentration of the pigments: chlorophyll a, chlorophyll 6 and fucoxanthin and the rate of light‐saturated photosynthesis were followed every hour during the 24 hour period. Both the concentration of pigments and the photosynthetic activity showed a rhythmical variation. The concentration per cell of all three pigments examined increased during the development of the cells and decreased automatically during the period of cell division. An increase in the pigment concentration was found only in the light period. The rate of light‐saturated photosynthesis calculated per unit of cell number increased during the cell development and decreased during the division period. The increase in the photosynthetic activity at light‐saturation started about 4 hours after the end of cell division, which was 4 hours before the light was turned on while the increase in the concentration of chlorophyll a first started 1–2 hours after this moment.

The variation in photosynthetic activity was compared with that found by other workers. The results found with Chlorella ellipsoidea by Japanese scientists (Nihci et al.) was explained as an inhibition phenomenon because the cells were not adapted to the experimental conditions.
Influence of Iodine and Bromine on Growth of Some Red Algae in Axenic Culture
Authors: Fries Lisbeth
Published: April 2006

Some red algae in axenic culture have been cultivated with different additions of iodine and bromine. Polysiphonia urceolata appeared to have an absolute demand for iodine. Additions could be made either as organically bound iodine or as inorganic iodine. A linear correlation between amount of added iodide and growth was found for iodide concentrations from 1 μmol up to at least 8 μmμmumol per 1. Nemalion proved to be indifferent to iodide additions, while Goniotrichum elegans was inhibited by concentrations higher than 0.4 μumol per 1, which corresponds to that of natural seawater.

High additions of iodine generally inhibited growth of nonaxenic algae. Acrochaetium made an exception, being stimulated by 4 μumol per I.

Bromine in the same concentration as that of seawater, viz. 814.3 μmol pa 1 inhibited growth of most species, but amounts smaller than 50 μumol had in some experiments a slightly increasing effect. Bromine seems, however, not to play an essential part in the metabolism of Polysiphonia urceolata.
Nitrogen Fixation by the Blue‐green Alga Anabaena flos‐aquae A‐37
Authors: Davis Edith B. , Tischer R. G. , Brown Lewis R.
Published: April 2006

Nitrogen fixation has been demonstrated in a bacteria‐free culture of a semithermophilic blue‐green alga, Anabaena flos aquae A‐37, employing the criterion of an increase in cellular nitrogen as a basis for determining nitrogen fixation. This is apparently the first time that nitrogen fixation has been demonstrated in a pure culture of a blue‐green alga which grows at 40 C and which produces abundant quantities of an extracellular heteropolysaccharide.
Internal Control of Rate of Leaf Production in Sngar Beet
Authors: Humphries E. C.
Published: April 2006

The theory that the rate at which leaves appear is little affected by the current environment has been tested with sugar‐beet plants. Seedlings were raised vinder 4 different conditions, viz., 8 hour photoperiod 20°C, 16 hour photoperiod 20°, continuous light or in the glasshouse. After 2 weeks all were put in the glasshouse under the same growing conditions. The treatments wbich the seedlings received continued to affect the rate at which leaves were produced during the next 20 weeks.
Photosynthetic Adaptation to Light Intensity in Plants Native to Shaded and Exposed Habitats
Authors: Björkman Olle , Holmgren Paul
Published: April 2006

Photosynthetic adaptation to light intensity has been studied in clones of populations from shaded and exposed habitats of Rumex acetosa and Geum rivale. Clones of the shade species Lamium galeobdolon and the sun species Plantago lanceolata were also included for comparison. The plants were grown under controlled conditions at a high and a low light intensity. The capacity of photosynthetic carbon dioxide uptake at low as well as at saturating light intensities was determined on single attached leaves.

As was previously demonstrated in Solidago virgaurea, clones of populations native to shaded and to exposed environments show differences in the photosynthetic response to light intensity during growth. The data provide evidence that populations of the same species native to habitats with contrasting light intensities differ in their photosynthetic properties in an adaptive manner Ln a similar mode as sun and shade species.
Alteration in the Geotropic Response of Allium Seedlings by Growth Regulators
Authors: Guha Sipra , Maheshwari S. C. , Jouri B. M.
Published: April 2006

Indoleacetic acid (1AA) brings about a striking alteration in the normal geotropic response in the seedlings of onion and several other species of Allium. The seedlings which are normally positively geotropic, become ageotropic. Besides IAA several other auxins like IBA, NAA and 2,4‐D also showed a similar response. An anti‐auxin like triiodobenzoic acid (TIBA) enhanced the auxin‐effect instead of reversing it. A marked enhancement of the auxin‐effect was also brought about when sucrose (in the culture medium) was replaced by L‐arabinose which appeared to act synergistically with the auxin.
Effect of Chrysanthemum Plant Extract on Flower Initiation in Short‐Day Plants
Authors: Biswas P. K. , Paul K. B. , Henderson J. H. M.
Published: April 2006

An extract was prepared from Chrysanthemum plants in flower. It was separated into eight different fractions putting emphasis on the sterol components of the extracts. Fractions 5 and 6 were found to contain active substance (s), which to some extent, brought about floral bud initiation in both Chrysanthemum and Xanthium.

The active substance (s) present in the above two fractions might be a sterol (s), similar to those of sitosterol and stigmasterol or other related compounds.

Gibberellic acid brought about stem elongation as usual, but was found ineffective in causing any tissue differentiation in both Chrysanthemum and Xanthium.

Investigations are underway to separate and identify the different compounds present in fractions 5 and 6. The effects of these compounds on test plants, both individually and in combinations, might provide some valuable information as to the nature of the flowering hormone.
The Effect of Light, Carhon Dioxide, and Nitrogen Nutrition on the Incorporation of S from External Sulphate into Different S‐Containing Fractions in Scenedesmus, with Special Reference to Lipid S
Authors: Kylin Anders
Published: April 2006

The experiments showed that incorporation of S from the sulphate in the medium into normal cells of Scenedesmus was enhanced by light, relatively most in the case of lipid S and least in the inorganic sulphate fraction. The effects of light were, generally, increased by the presence of CO2 and nitrogen salts. CO2 did not significantly alter the proportions between the fractions, but the presence of nitrogen increased the formation of protein S more than the synthesis of S‐containing lipids.—It is suggested that lipid S is formed as a “sink”, when a step between sulpbite and ‐SH becomes increasingly rate‐limiting in the overall reduction of sulphate. Furthermore, incorporation as SO42− and as lipid S may be regulated by more or less independent processes.
Effect of Tobacco Mosaic Virus Infection on Amino Acid Incorporation into Isolated Mitochondria from Tobacco Leaves
Authors: Takahashi Tsuyoshi , Hirai Tokuzo
Published: April 2006

Mitochondria isolated from tobacco leaves incorporated 14C‐leucine into the protein and the rate was enhanced by tobacco mosaic virus (TMV) infection as compared with noninfected level. In vitro amino acid incorporation by mitochondria required adenosine triphosphate (ATP), Mg2+, and KC1 and the energy sources from oxidative phosphorylation as well as from ATP‐generating system. This incorporation was inhibited by ribonuclease (RNase), deoxyribonuclease (DNase), actinomycin D, mitomycin C, puromycin, and chloramphenicol added in the reaction medium. The pretreatment of the mitochondria with DNase and actinomycin D reduced the rate of incorporation. The mitochondria incorporated 3H‐guanosine triphosphate (GTP) and this activity was blocked by actinomycin D. The presence in this system of 15,000 g supernatant cell sap fraction or bacterial contamination was carefully checked obtaining a negative result. The reaction product into which l4C‐amino acids incorporated was solubilized by trypsin. The nature of the amino acid incorporating activity of isolated mitochondria obtained from TMV‐infected tobacco leaves is discussed.