bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracellular Organic Carbon from Some Green Algae
Authors: Forsberg Curt , Taube ÖRn
Published: April 2006

A preliminary study of the extracellular organic carbon in cultures of Ankistro desmus falcatus, Scenedesmus quadricauda, Chlorella pyrenotdosa and Crucigenia tetrapedia have been performed. Carbon analyses, parallel to the increase in cell numbers, were made with an infrared analyzer after oxidation of the organic carbon to CO2. During the phase of declining relative growth rate and the stationary phase of growth the species excreted organic carbon. For Scenedesmus and Ankistrodesmus an uptake period took place before the excretion period. Approximately 500 · 106 cells/1 were required until excretion started for the former species. The highest figures for the organic carbon liberated by the four species ranged between 3 and 9 mg/l (approx. 8–23 mg organic matter/I). When distributed per cell the extracellular carbon corresponded to 1–3 μg · 10−6 with a mean for the average excretion for the species tested of 6 · 10−8μg/cell · day. For Scenedesmus the extracellular carbon was calculated to be 2–5 per cent of the cell‐bound carbon.
Cytokinin‐like Activities of 4‐Benzylaminobenzimidazole
Authors: Kuraishi Susumu , Yamaki Tosmo
Published: April 2006

A new compound, 4‐benzylaminobenzimidazole was synthesized. The only difference between benzylaminobenzimidazole and benzylaminopurine is the presence in the former of carbon atoms instead of the nitrogen at positions 1 and 3 of the purine ring. Although the new compound has no purine ring in the molecule, it has several cytokinin activities such as stimulation of leaf growth in Raphanus and retention of chlorophyll in Brassica leaves. Benzylaminobenzimidazole has no effect on germination of tobacco seeds kept in the dark.
Studies of the Cultural Physiology of the Lichen Alga Trebouxia
Authors: Fox Cecil H.
Published: April 2006

The pholosynthetic growth of three species of Trebouxia was so slow as to preclude the usual inorganic methods of algal cultivation. Heterotrophic growth was much stronger — as many as 0.4 doublings per day were obtained in Bold's solution with glucose and amino acid hydrolysates. Ammonium salts of inorganic acids could not be used in the culture medium because they caused excessive reductions in pH. Although the organisms showed variations in their growth response to amino acids, no specific requirement was found. T. erici produced significantly lower quantities of photosynthetic pigments in the dark. Of the nineteen carbohydrates tested, only glucose, mannitol, and galactosc stimulated growth of the algae. Preliminary studies showed that Trebouxia incorporated 14CO2 more slowly than Chlorella pyrenoidosa. However, the carbon fixed by Trebouxia remained soluble in 80% ethanol longer than Chlorella. The carbon incorporated as CO2 in short term experiments was greater than would be expected from the growth rates of the organisms studied.
Nucleic Acid Metabolism Involved in Auxin‐induced Elongation of Yeast Cells
Authors: Shimoda Chikashi , Masuda Yoshio , Yanagishima Naohiko
Published: April 2006

The following results were obtained using a variant yeast strain, N55, which can respond to the cell‐elongating action of auxin.

Base analogs of nucleic acids (2‐thiouracil, 8‐azaguanine, and 5‐fluorouracil) inhibited the auxin‐induced elongation of yeast cells only when they were added to the preculture prior to auxin treatment. The inhibitory effect of 2‐thiouracil and 5‐fluorouracil was reversed by uracil and that of 8‐azaguanine by guanine. Actino‐mycin D inhibited the auxin‐induced elongation when given to the culture containing auxin, but not when given to the preculture. The similarity in these respects between yeast and tissues of higher plants is discussed.
Carotenoid Synthesis in Leaves of Etiolated Wheat Seedlings after Varying Light and Dark Treatments
Authors: Virgin Hemming I.
Published: April 2006

A short impulse of red light has a varying effect on carotenoid synthesis in dark‐grown wheat seedlings. Except for β‐carotene, which remains unchanged in the dark (it increases in continuous light), the carotenoid synthesis shows the same tendency as during constant irradiation. Thus, lutein and neoxanthin slowly increases, while violaxanthin decreases. During a period of constant light following various periods of darkness after the short impulse of light, the pigment changes correspond to those occurring in the dark, but are much more pronounced. The changes are discussed on the basis of phytochrome action.
The Changes of The Level of Triterpenoids in Calendula officinalis during Vegetation
Authors: Kasprzyk Zofia , Fonberg‐Broczek Monika
Published: April 2006

Using thin‐layer chromatography for separation and colorimetric test with CoClj for determination, qualitative and quantitative composition of triterpenoids was estimated in Calendula officinalis dining vegetation. It was found that sterols and oleanolic acid as well as trace amounts of triterpenic monols occur in all organs of the plant during the whole vegetative period. Triterpenic diols and greater quantities of triterpenic monols appear in flowers. The biosynthesis rate of triterpcnoids is highest in young organs of the plant that is in seedlings, young leaves and flower buds. During flowering the content of sterols and oleanolic acid increases in all plant organs except of old leaves. A high level of oleanolic acid in the root during the flowering period implies that oleanolic acid glycosides can be transported from older leaves to underground parts of the plant. Biosynthesis of triterpenic monols, Ψ‐taraxasterol and taraxasterol, precedes the formation of the diols faradiol and arnidiol. It can be inferred from the course of accumulation of these compounds that monols are the precursors of diols and that hydroxylation occurs in flowers.
Scopoletin and Polyphenol‐Induced Lag in Peroxidase Catalyzed Oxidation of Indole‐3‐acetic Acid
Authors: Schaeffer G. W. , Buta J. G. , Sharpe F.
Published: April 2006

The rate of initial indole‐3‐acetic acid (IAA) oxidation with horseradish peroxidase is modified with scopoletin, scopolin and other phenolic derivatives. In the presence of phenolics there is an initial lag phase in the oxidation. The early lag is dissipated enzymatically after which the rale of IAA oxidation again returns to normal. Chlorogenic and sinapic acids produce the longest lag periods of the compounds reported here, whereas the glucoside, scopolin, produced the least inhibition. Scopoletin is more than 10× as inhibitory as scopolin.
Metabolism of DL‐Tryptophan‐3‐14C by the Fruitlets of Citrus aurantifolia
Authors: Khalifah Rashad A.
Published: April 2006

Developing lime fruit [Citrus aurantifolia (Christm.) Swingle] was supplied with dl‐tryptophan‐3‐14C in a special medium. An incubation period of six hours was sufficient for the radioactivity to reach an equilibrium between the fruit tissue and the incubation medium. Analyses of the fruit tissue and the medium for acidic and neutral metabolites of tryptophan indicated the existence of indolic products. The auxin indole‐3‐acetic acid (IAA) was identified among the products by dry column chromatography and biological assay. Other acidic metabolites included indolepyruvic acid and an unidentified material. Neutral metabolites included indolealdehyde, indoleacetaldehyde, and two unidentified compounds. Biological activity in the Avena curvature test was obtained from extracted compounds which corresponded to IAA and indolepyruvic acid in the acidic fraction and indoleacetaldehyde in the neutral fraction. Radioactive tryptophan was also found in both the acidic and the neutral fractions due to its amphoteric nature. The experiment demonstrated the conversion of tryptophan to its indolic metabolites, including indole‐3‐acetic acid, in this Citrus tissue.
The Distribution of Acidic and Neutral Peptidases in Barley and Wheat Kernels
Authors: Prentice Neville , Burger W. C. , Kastenschmidt Jeannine , Huddle John David
Published: April 2006

The activity of barley and wheat peptidases which hydrolyze alpha‐N‐benzoyl‐dl‐arginine‐p‐nitronnilide (BAPA) and alpha‐N‐benzoyl‐l‐arginine ethyl ester (BAEE) has been measured in proximal and distal portions of ungerminated grain and in these tissues during 6 and 7 day incubations.

The proximal portion of ungerminated barleys contained the major part of both the acidic (BAPA‐ase and acidic BAEE‐ase) and neutral (neutral BAEE‐ase) peptidases. In ungcrminated wheat these acidic and neutral peptidases were nearly evenly distributed between the proximal and dislal portions. Commercial wheat embryo was very high in acidic peptidase but contained no neutral peptidase.

During the germination of both wheat and barleys, acidic and neutral peptidase activity in the seedlings increased with time. No such consistent increase was observed for aleurone and starchy endosperm tissue for any of these grains.

Aleurone and starchy endosperm tissue incubated in the absence of the proximal portion of the kernel showed reduced peptidase activities.
Membrane Functions and Tolerance to Aromatic Hydrocarbon Fungitoxicants in Conidia of Fusarium solani
Authors: Georgopoulos S. G. , Zafiratos Catherine , Georgiadis Eugenia
Published: April 2006

With the use of 32P‐labeled phosphate and 42K2CO3 the effect of diphenyl on permeability and uptake properties of the cytoplasmic membrane in wild type and diphenyl‐tolerant mutant conidia of Fusarium solani f. cucurbitae was studied. No general damage to the membrane with unspecific leakage of cell constituents was demonstrated under conditions in which diphenyl prevents germination of wild type conidia.

The fresh conidia do not require exogenous supply of energy for the uptake of phosphate or of potassium. In the wild type the entry of 32P is inhibited but that of 42K strikingly stimulated by diphenyl. Independently of the tolerant mutant gene present, the mutant conidia are significantly less sensitive to the phosphate uptake inhibition and not affected at all by diphenyl with respect to the uptake of potassium. The latter difference from the wild type seems to indicate genetic control of some property of the potassium transport system in this fungus.
14C‐Studies on Apple Trees. I. The Effect of the Fruit on the Translocation and Distribution of Photosynthates
Authors: Hansen Poul
Published: April 2006

The presence of fruits affects the translocation and distribution of photosynthates from apple leaves to other organs of the tree. An attempt has been made to study the relationship in greater detail by following the distribution of 14C introduced in the form of 14CO2 on shoots with and without fruits, respectively. Determinations of the 14C‐content were made on different parts of the shoot sampled at varying intervals after the introduction of the tracer. The l4C‐labelling and the content of sorbitol and sugar in the leaves were determined by means of paper chromatography.

A total of nearly 90 per cent of the 14C taken up by the leaves can be transferred to a fruit close by, the majority during the first 4 to 5 days following the addition of the 14C. The content of 14C in the leaves is reduced more rapidly in shoots with fruits than in those without. Young leaves retain more of the added 14C than do fully developed ones.

The greatest changes with time are found in the methanol‐soluble 14C‐compounds. Immediately following application, the leaves contain 58 to 80 per cent of the 14C added in sorbitol, 7 to 9 per cent in sucrose, and 1 to 4 per cent in the form of glucose. Within 5 days after the introduction of 14C the amount of 14C‐sorbitol is reduced very considerably, while in certain cases the amount of 14C‐glucose increases. The 14C‐sorbitol content was higher in leaves from shoots without fruits than in those from fruit‐bearing shoots, and this applied also to the total contents of sorbitol and of glucose.
Effect of Variation of Sporulation Time and Temperature on Thermostability of Bacillus cereus Spores
Authors: Lundgren Lillian
Published: April 2006

The optimum temperature for sporulation of a strain of Bacillus cereus was estimated at 30°–35°C, where the maximum yield of spores was obtained between 18 and 24 hours’ incubation. Sporulation was more rapid, but less extensive at 40°C and did not occur at all at 45°C.

The heat resistance of the spores increased with the sporulation temperature from 20° to 40°C. The spores appear to be more susceptible to heat destruction in the early stage of spore production than after further incubation.
The Influence of Temperature on Floral Initiation in the Olive
Authors: Hackett Wesley P. , Hartmann Hudson T.
Published: April 2006

Floral initiation is completely inhibited when the olive is grown in a glasshouse at a minimum temperature of 16°C and a maximum temperature of 27°–30°C but occurs when it is grown at natural winter conditions in California. This study was undertaken to determine more specifically the temperature requirements for flowering and to show the relation of temperature treatment to hud development and floral initiation. Results of experiments performed with trees in containers grown at constant temperatures in controlled environment growth rooms show that the optimum temperature for flowering is 10°–13°C. Either higher (18°C) or lower (4°C) temperatures inhibit flowering completely. Morphological studies show that axis elongation and floral initiation occur in buds during temperature treatment at 10°C and 13°C but fail to occur during 4°C or 18°C treatments, or following these treatments when the temperature is raised to 21°C. When plants were exposed to 13°C for varying durations, it was found that no inflorescences formed after a 7.5 week exposure but that many formed after an 11‐week exposure. A subsequent experiment showed that many more inflorescences formed after a 10‐week exposure at 13°C than after 9 weeks exposure. Morphological changes in the bud seem to be associated with this increase in flowering affected by duration of treatment.
Direct and Synergistic Influence of Tweens on Avena Coleoptile Section Elongation
Authors: Méndez J. , Vázquez A. , Mato M. C. , Vieitez E.
Published: April 2006

The Avena cylinder test was used with Tweens at 3 different concentrations with and without the addition of varying concentrations of IAA.

Tween 20 was a toxic substance for oat coleoptile sections at such concentration as 0.1 %. Tween 40 gave erratic results and Tween 80 has practically no direct effect on cell elongation. An inhibitory effect continues to increase with increasing HLB values.

The second object of this experiment was to ascertain whether cell elongation promoted by IAA would be enhanced by osmotic substances such as Tweens, as consequence of a specific modification in the permeability when the membranes are lipid in nature. The hypothesis was supported by the experimental work when 0.05 % Tweens were assayed although the inverse was also true, with concentrations of Tweens as low as 0.01 %. Accordingly, evidence must be verified by further investigation.
Arsenite‐BAL as an Inhibitor of Germination
Authors: McDonough Walter T.
Published: April 2006

Imbibition of light‐sensitive lettuce seeds in mixed solutions of sodium arsenite and 2,3‐dimercaptopropanol (BAL) inhibits light‐induced germination more potently than does arsenite alone, particularly at higher temperatures. There is limited reversal of the enhanced inhibition at high BAL/arsenite ratios. The complex is also more inhibitory than arsenite after shorter periods of imbibition. Monothiol compounds do not give the increased inhibition, nor do combinations of BAL with other thiol group reagents. Greater penetrability, possibly into some internal compartment of the cell, is suggested as the cause of the enhancement. Induction of germination by gibberellic acid or low temperature is equally sensitive to arsenite‐BAL. The extent of the inhibition of germination of 9 other species by arsenite‐BAL is not clearly related to their light‐sensitivity.
Nitrate Reductase in the Citrus Plant: Properties, Assay Conditions and Distribution within the Plant
Authors: Bar‐Akiva A. , Sagiv J.
Published: April 2006

A nitrate reductase enzyme preparation has been obtained from citrus plant tissue extract and the optimal assay conditions have been established. The enzyme has been found to be similar or even identical to those of many other annual plants, i.e., cysteine is required for its extraction in the active state, it is DPNH‐specific, and in some cases FAD‐dependent.

Comparisons were made between the activity measured in fragments with that of the extracted preparation of the same plant tissues.

The occurrence of the enzymes was demonstrated in germinating seeds, cotyledons, rootlets, shoots, leaves and fruit of citrus plants.
The Effect of Blue and Red Light on NADP‐linked Glyceraldehydephosphate Dehydrogenases in Excised Roots
Authors: Björn L. O.
Published: April 2006

d‐Glyceraldehyde 3‐phosphate: NADP oxidoreductasc (phosphorylating), EC 1.2. 1.13, is formed in excised roots of wheat and pea grown in blue light, but not in red light or darkness. The nonphosphorylating d‐glyceraldehyde 3‐phosphate: NADP oxidoreductase, EC 1.2.1.9, if present at all, constitutes only a minor fraction of the total activity. In wheat roots the time‐course for increase in enzyme activity agrees completely with the time course for increase in chlorophyll content, with a lag phase of 3 days for both. The results for pea roots are similar, but less clear‐cut due to interfering enzymes. The results are discussed with reference to a previously published scheme for chloroplast development.
The Use of Polarography in the Assay of Oxygen Diffusing from Roots in Anaerobic Media
Authors: Armstrong W.
Published: April 2006

A “polarographic” technique by which the rate of outward diffusion of oxygen from plant roots may be measured, is described in detail.

Oxygen has been found to diffuse from the roots of all of the ten species of bog‐plants so far tested, and the oxygen diffusion rates (ODR) of eight of these species show the existence of interspecific differences. Model roots made from silicone rubber tubing give “polarographs” identical with those obtained around the living roots.

Suberization accompanying root maturation is thought to account for a. the association of oxygen diffusion with the apical regions of roots, and b. the lowered diffusion rates associated with winter dormancy. This localisation of root oxygen diffusion may be of survival value in reduced soils.

Experiments suggest that aerenchyma can function as an oxygen reservoir in the plant if the stomata were closed for long periods.

Calculations of expected ODR based on the internal gas concentrations of a model system give readings very similar to the ODR obtained experimentally using the silicone rubber tubing models.

Further calculations, based on reported internal gas concentrations for Menyanthes, rice, Spartina, and Schoenus, also show a close similarity between real and expected values. It is concluded that in these species at least, there is negligible resistance in certain regions of the root to the passage of oxygen from the root intercellular spaces to the surrounding medium.

Results have shown that root bases are relatively impermeable to oxygen, and it is suggested that oxygen intake into roots in the basal regions reported by other workers, probably occurs through basally‐borne laterals.

One important function of diffusing oxygen from the root is probably the supply of an external source of oxygen to the root meristem.
The Influence of Dormancy‐Inducing Desiccation Treatments on the Respiration and Germination of Sorghum
Authors: Nutile G. E. , Woodstock L W.
Published: April 2006

Seeds of sorghum (Sorghum vulgare Pers.) dried in a forced‐air dryer from an initial moisture content of 12 percent to either 10 percent or 7 percent exhibited physiological dormancy. Dormancy was more marked in seeds dried to 7 percent than to 10 percent moisture, and was more pronounced in germination at 15° or 20° than at 25°C. Expression of dormancy at the lower temperatures was influenced decidedly by the four germination media (paper towels, blotters, sand, and soil). Percent dormancy was lowest in towels and highest in soil. Osmotic tension is suggested to be a factor influencing dormancy in these media. Dormancy was relieved by cutting the integumentary membrane or by rehydration of dried seeds. Respiration rates were lower and respiratory quotients higher in dormant seeds than in the controls. Differences in respiration rates were detected within 2 hours after the start of imbibition.

Dormancy and differences in respiration rates appear to be associated with changes induced in the seeds by drying.
Relationships between Photo‐induced and Gravity‐induced Electrical Potentials in Zea Mays
Authors: Johnsson Anders
Published: April 2006

A comparison is made between gravity‐induced and light‐induced transversal electrical potentials in excised coleoptiles of Zea Mays. The potentials are measured with a vibrating condensor method, thus the plants are not touched at the measuring point. It is found that all experimental evidence supports the assumption that the reaction chains leading to the potentials are identical in the two cases, apart of course from the perception stages. This theory is based on the following points which have been experimentally verified:

The stimulus‐response functions are quite similar. In both cases the voltage is a logarithmic function of the stimulation time (at least for shorter stimulation times). When continuous stimulation is used, the stimulation time must exceed a threshold value to cause a transversal potential.

Some inhibitors (DNP and NaN3) diminish both types of potential.

A latency time is found in photo‐induced potentials as well as in gravity‐induced ones. The Q10 for the latency period of the photo‐induced potentials is found to be 2.8, which is the same as for the chemical part of the latency period of the gravity‐induced potentials.

In both cases the potential‐generating process is controlled by a Q10 of 1.6–1.8, thus indicating this process as separate from the one mentioned above.

The temperature dependence of the maximum voltage follows in both cases the same pattern with a maximum at about 25–30°C.

Some measurements on potential oscillations are described and discussed. The origin of the potentials is discussed.
Effect of 2‐deoxy‐D‐glucose on the Respiration of Tropical Anthracnose Fungi
Authors: Greene G. L.
Published: April 2006

This study begins an investigation of the chemical activities of one of the most destructive groups of spoilage organisms of tropical foods, the anthracnose fungi. The present paper treats of an introductory investigation on carbohydrate metabolism.

Two fungi isolated from rotted banana tissue, Gloeosporium musarum and Colletotrichum gloeosporioides, were grown in the presence of 2‐deoxy‐D‐glucose, a metabolic blocking agent, in shake culture. The mycelia produced were studied in the Warburg respirometer in the presence of glucose, 2‐deoxyglucose, and 2,4‐dinitrophenol.

Gloeosporium musarum was found to be incapable of growth in the presence of 2‐deoxyglucose as the sole carbon source, but did grow when glucose was added.

Colletotrichum gloeosporioides grew normally, but at a slower rate on 2‐deoxyglucose than on glucose. Glucose grown G. musarum and C. gloeosporioides both exhibited respiratory inhibition in the presence of 2‐deoxyglucose, whereas 2‐deoxyglucose adapted C. gloeosporioides did not. The uncoupling agent 2, 4‐dinitrophenol induced respiratory stimulation except in the presence of 2‐deoxyglucose in glucose grown C. gloeosporioides where it caused a drop in oxygen uptake.
The Metabolism of Carbon‐14 Specifically Labelled Glucose in Leaves Showing Tobacco Mosaic Virus Induced Local Necrotic Lesions
Authors: Merrett M. J. , Sunderland D. W.
Published: April 2006

Glucose metabolism of healthy and tobacco mosaic virus‐infected leaf‐discs of Nicotiana tabocum L. var. Xanthi showing local‐necrotic lesions was investigated using glucose‐14C. Local lesion formation following inoculation with tobacco mosaic virus resulted in enhanced glucose metabolism reflected by an increased rate of release of 14CO2 from glucose‐U‐14C and greater incorporation of 14C into all cell fractions. When specifically labelled glucose was fed to healthy and tobacco mosaic virus infected leaves, the C6/C1 ratio (rate of release of 14CO2 from glucose‐6‐14C/rate of release of 14CO2 from glucose‐l‐14C) was similar for healthy and virus‐infected leaves. The C6/C1 ratios recorded from 0.30 to 0.50 indicate that both the glycolytic and pentose phosphate pathways participate in glucose catobolism in healthy and virus‐infected leaves. Although the C6/C1 ratio was the same as that of the healthy leaf the rate of release of 14CO2 from glucose‐6‐14C and glucose‐1‐14C was greatly increased in the virus‐infected leaf. The increased glucose catabolism occurs by both glycolytic and pentose phosphate pathways in the virus‐infected leaf.
The Cultivation of Tissues of Cupressus lusitanica in vitro
Authors: Borchert Rolf
Published: April 2006

Conditions for In vitro culture of initial explants of Cupressus lusitanica were determined as the first step of an investigation of physiological differences between tissues obtained from plants, or plant parts, of different ages. Explants proliferated well on a basal agar medium containing only Heller's mineral salts and sucrose. Addition of several vitamins, phytohormones, and coconut water to this basal medium stimulated callus growth only slightly or not at all, and transplanted callus soon died. Proliferation of initial explants was considerably stimulated by increasing the concentration of mineral salts in the medium, and the growth habit changed from compact to friable. Callus could be transplanted to, and maintained on, a high‐salt medium enriched by vitamins. Whereas added auxins still stimulated proliferation of initial explants and transplanted callus only slightly, added coconut water was considerably more effective than on basal medium. Thus results confirm observations by others with tobacco tissues: Additions of phytohormones and other organic substances may not exert their potential effects if growth is limited by sub‐optimal mineral nutrition.
The Effect of ATP (Disodium Salt) upon Rotational Streaming
Authors: Pop Emil , Soran Viorel , Lazǎr Georgeta
Published: April 2006

Through the continuous treatment with various solutions of ATP disodium salt the rotational streaming of the cytoplasma in barley root hairs has been stimulated about 1.2–1.7 times. With the concentrations employed the stimulation of the streaming did not depend on the external ATP supply, but on the initial rate of streaming. It is assumed that the main source of energy supporting the protoplasmic streaming is ATP. Therefore, the results obtained may be interpreted on the basis of variations in ATP content and its degradation products. The differences between initial rates of streaming are supposed to be due to variations of the endogenous ATP level. The ATP taken up probably stimulates the rotational streaming both through the supply of delivered energy and by lowering the cytoplasm viscosity. On the contrary, products of ATP hydrolysis increase the cytoplasm viscosity and induce a lowering or even cessation of the streaming.
Subcellular Location of Phosphoglucomutase and UDP Glucose Pyrophosphorylase in Avena Coleoptiles
Authors: Hall M. A. , Ordin L.
Published: April 2006

Extraction of phosphoglucomutuse and UDP glucose pyrophosphorylase from oat coleoptiles using both aqueous and non‐aqueous systems showed that both enzymes are largely soluble. Phosphoglucomutase was completely absent from the cell wall fraction. The inhibition of phosphoglucomutase by peroxyacetyl nitrate was confirmed and the enzyme in the subcellular participate fractions was shown to be more inhibited than that in the soluble fraction. UDP glucose pyrophosphorylase was not inhibited by peroxyacetyl nitrate or ozone in vivo but was inhibited by peroxyacetyl nitrate in vitro. The SH reagents, iodoacetamide and p‐chloromercuribenzoate, inhibited phosphoglucomutase severely but UDP glucose pyrophosphorylase moderately or not at all.
The Components of the CO2‐Indluced Stomatal Movements
Authors: Stålfelt M. G.
Published: April 2006

Leaf discs of Vicia Faba were allowed to float on water in glass dishes placed in vessels containing KOH. The vessels were kept in darkness at constant temperature. The stomatal width and osmotic values of the guard cells and epidermal cells were measured, generally at one‐hour intervals.

When the CO2 content of the air surrounding the leaf specimen falls, it causes a disturbance in the osmotic equilibrium between guard cells and epidermal cells. Sometimes the changes start in the form of falling osmotic values in both kinds of cell. In other cases the values rise, and in still others the changes may be confined chiefly to one of these kinds of cell. Since the changes are not the same in guard cells and epidermal cells, the osmotic difference between them rises or falls. The difference rises during the time immediately after removal of CO2 from the surrounding air. This causes an osmotic surplus to arise or increase in the guard cells. Later, this change may take place in the opposite direction. The stomatal movements occurring simultaneously follow, on broad lines, the osmotic surplus of the guard cells.

Consequently, the CO2‐induced stomatal movement is the result of an interaction between an active component—i.e., the intrinsic osmotic changes in the guard cells—and an osmopassive component, by which is meant here the osmotic changes in the epidermal cells.
Effect of Gibberellic Acid and Cycocel on Tryptophan Metabolism and Auxin Destruction in the Sunflower Seedling
Authors: Valdovinos Jack G. , Ernest Leland C.
Published: April 2006

A comparative study of tryptophan conversion in different regions of the sunflower seedling indicates that the regions most active in converting tryptophan on a pathway to auxin are the root apical segments and young leaves; next highest in activity is the cotyledonary tissue. The stem apex proper with leaf primordia is less active than the above regions in converting the auxin precursor. Hypocotyl tissue was observed to be least active. Pre‐treatment of the apical bud region of the stem with gibberellic acid (GA) gives rise to tryptophan conversion rates which are 2.1 times those in untreated seedlings. The enhanced tryptophan conversion in the apical bud is followed by an increased elongation rate of the 1st internode which is 2.2 times that in the 1st internode of untreated seedlings. Treatment of the seedlings with Cycocel [(2‐chloroethyl)trimethylamnionium chloride] does not reduce tryptophan conversion in the apical bud region of the seedling although elongation of the stem is greatly retarded.

Indoleacetic acid (IAA) destruction in cell free preparations as well as in whole sections of the elongating region of the seedling stem was studied. IAA‐1‐14C destruction rates with the release of 14CO2 in whole sections of 1st internode tissue were approximately 3 times those in cell free preparations of the same region. No significant changes in IAA destruction rates in seedlings pre‐treated with GA or Cycocel were observed.
Effect of Some Dithiocarbamates on Respiration Activity of a Myxomycete
Authors: de Meester C. , Lambert R. , Wiaux A.
Published: April 2006

The presenl article aims at giving some information concerning the mode of action of three dithiocarbamates: ferric dimethyldithiocarbamate (Ferbam), zinc dimethyl‐dithiocarbomate (Ziram) and tetramethylthiuram disulfide (Thiram). These inhibitors were tested on the respiratory activity of the Myxomycete: Physarum polycephalum. Its development is strongly inhibited at 285 mg/l. With such concentration, respiration measurements confirmed total inhibition of O2 uptake. After isolation of the mitochondria, the tests showed that there may be an inhibition of the succinic oxidase activity of this particulate fraction, at 28.5 mg/l of Thiram.

Heavy concentration of reduced glutathione (1.4 %) reversed partially this Inhibition. This seems to prove that succinic dehydrogenase is a typical SH‐type enzyme.
Oxidative Enzymes of Ceratocystis fimbriata Isolates Differing in Host Specificity
Authors: Meagher R. B. , DeVay J. E. , Kosuge T.
Published: April 2006

Eight isolates of Ceratocystis fimbriata differing in pathogenicity on sweet potato roots were compared in vitro for peroxidase, catalase and polyphenol oxidase activities.

Pathogenic isolates were generally lower in specific activities of peroxidase and catalase than the nonpathogenic isolates.

Cultures of pathogenic isolates were distinguished by black culture liquid compared to the yellow color of nonpathogenic isolates.

No consistent differences among the isolates were apparent when the specific activity of polyphenol oxidase preparations were compared on various phenolic substrates.

The peroxidase of C. fimbriata had an approximate molecular weight of 81,000 when compared with known protein standards on a column of Sephadex G‐100 dextran gel. Its substrate specificity differed from horseradish peroxidase in that it was nonreactive with guaiacol.
The Effects of Sucrose and Light on the Level of Soluble and Particle‐bound Ribonuclease Activities in Excised Avena Leaves
Authors: Udvardy J. , Farkas G. L. , Marré E. , Forth G.
Published: April 2006

Incubation of excised Avena leaves in a wet chamber in darkness resulted in an increase in both soluble and particle‐bound Rnase activities. Illumination promoted the increase in the total RNase which occurred upon leaf excision. The light‐induced increase in total RNase was due to an increase in soluble RNase. The increase in RNase activity in the particulate fraction was inhibited by illumination. Feeding 2 per cent sucrose to the tissues in the dark increased the level of soluble RNase and decreased the activity found in the particulate fraction. Treatment of the illuminated tissues with 10−4M dichlorophenyldimethylurea (DCMU) inhibited the effects of light on the RNase level. It is concluded that the light‐effect is explained at least in part by the photosynthetic production of sugars.

In excised leaves kept in darkness the RNA content rapidly decreased. Feeding sugars to or illumination of the tissues lowered the rate of RNA breakdown due to leaf excision. DCMU counteracted the light effect. In general, the decrease of RNA was repressed by all treatments leading to an inhibition of the increase of particulate RNase. On the other hand, the observed changes of the soluble RNase were not related with the variations of RNA.

Treatment with 3 M urea increased the RNase activity both in the particulate and the soluble fractions. The RNase activity of soluble preparations, partially purified on a Sephadex G‐50 column or by (NH4)2SO4 fractionation, was also stimulated by 3 M urea.

Treatment with 10−5M kinetin repressed the increase in RNase activity due to leaf excision both in the soluble and the particulate fractions.
Effect of Reciprocal Bud‐Graft Transfers Between Old Home and Bartlett Pears and Centrifugatiou on Trans‐location of Endogenous Growth Substances in Hardwood Cuttings
Authors: Fadl Mostafa S. , Hartmann Hudson T.
Published: April 2006

An investigation was made of the effect of bud‐graft exchanges between two pear varieties—the easily‐rooted Old Home and the hard‐to‐root Bartlett—on the root‐promoting activity of extracts obtained from basal segments of hardwood cuttings of each variety. The effect of a centrifugal force obtained from 2000 rpm for 30 minutes on the root‐promoting activity of diffusates and extracts from bases of centrifuged cuttings of these two varieties was also studied.

Bud exchange treatments showed no appreciable influence on the root‐promoting or inhibiting activity of basal extracts unless the transbudded shoots (used for making cuttings) were girdled one month prior to the sampling date; in such cases an influence did appear.

The centrifugation treatment increased the number of buds sprouting on cuttings. It also increased the root‐promoting activity of extracts from the basal parts of cuttings and of their growth‐active components (separated by paper chromalography) when bioassayed by the mung bean rooting test. Apparently some inhibitory materials from the buds were removed through the bases of the cuttings by centrifuging.
Metabolism of Maleic Hydrazide in Tea, Camellia sinensis
Authors: Biswas P. K. , Hall Oscar , Mayberry B. D.
Published: April 2006

The results obtained with tea plants treated with 14C‐maleic hydrazide indicate that tea plants can metabolize maleic hydrazide to some extent. According to autoradiographic studies, two radioactive spots were found on X‐ray films after exposure and development. Based on two‐dimensional paper chromatography, possible ring cleavage, and infrared spectroscopic techniques, the possible metabolic products are lactic acid, succinic acid, maleimide and hydrazine.

The biological activity of the metabolic products was tested by utilizing the Avena first internode test. Based on this investigation, it was noted that each radioactive area contained compound(s) that possess(es) some growth promoting properties. However, the results obtained with unknown number one (U1) indicate that it possesses greater growth‐promoting properties than unknown two (U2). finally, the approximate concentrations of U1 and U2 were determined by comparison with known concentrations of IAA and in relation to the amount of growth produced during the 19½‐hour period of incubation.
Studies on Cellular Site of Calcium Action in Promoting Pollen Growth
Authors: Kwack Beyoung H.
Published: April 2006

Studies were conducted to determine cellular site of Ca action in promoting pollen growth of Crinum asiaticum and a few other species.

The following experimental results have strongly indicated that Ca binding takes place in pectins of the pollen tube walls. This appeared to increase the wall rigidity and to regulate permeability of the pollen cells thereby enhancing pollen growth.

Radioactive Ca incorporation was observed exclusively in the pollen tube wall regions. The promoting action of Ca on pollen growth disappeared when pectinase was supplemented to the media. This was not the case with cellulase and other enzymes used. Methyl donors promoted pollen growth, and the promotion was more than doubled if Ca ions were present. Ethionine, on the other hand, inhibited tube elongation and exhibited no Ca effect.

Growth of pollen tubes in oscillaled liquid media during elongation was poorer than growth in standing media. The Ca effect was also reduced when pollen was oscillated. The observations made of the reduced rate of 45Ca incorporation when pollen was washed in water, and the hydroxylamineferric chloride test, have indicated that a considerable portion of these pectins are cold‐water soluble.
Effects of Auxin and Kinetin on the Development and Differentiation of Potato Tissue Cultured in vitro
Authors: Okazawa Yozo , Katsura Naoki , Tagawa Takashi
Published: April 2006

The present investigation deals with the influence of auxin and kinetin on cultures of potato tuber tissue, and the effect of the size of the explants on the organ formation.

Exogenous application of auxin is indispensable for initiating callus formation of the tissue, but kinetin is not necessarily required. Kinetin serves to maintain the callus development, indicating that the stimulation of callus growth due to exogenous auxin would presumably be mediated by the addition of kinetin to the medium.

A relatively low concentration of auxin in the medium is required for root formation on the culture. In this case, IAA is markedly superior to any other auxin in root forming activity. NAA is somewhat less effective than IAA, and 2,4‐D shows no stimulation on root formation.

The growth and organ formation of potato tissue are remarkably affected By the variation in sizes of the explants. Spontaneous formation of a sprout was observed on the large explant in the medium without auxin. Small explants form only callus or roots in the presence of auxin and kinetin irrespective of combination or concentration. It seems likely that a sufficient amount of stimulus for initiation of bud formation may be contained in the large sized explant itself.
The Auxin Level of Begonia Leaves in Relation to their Regeneration Ability
Authors: Heide O. M.
Published: April 2006

The level of endogenous growth substances in leaves of Begonia × cheimantha Everett plants grown under various temperature and day‐length regimes has been studied.

In the acidic fraction of ether extracts two main growth promoting factors were present. Evidence is presented indicating that one of these is indole‐3‐aeetic acid (IAA), the other a gibberellin‐like factor. The level of both these factors was always higher in extracts of long day grown plants than in those from short days. Similarly, high temperature (20 and 25°C) caused an increase in the level of the auxin, whereas the gibberellin activity was not much affected by temperature. Several growth promoting factors were present also in the non‐acidic fraction, but their identity is not known.

The results are discussed in relation to the effect of environment on the regeneration ability of the Begonia leaves. The results of these and previous investigations strongly support the hypothesis that short days and low temperature increase the budding ability and reduce the rooting ability of Begonia leaves through a lowering of the ratio of endogenous auxins to endogenous cytokinins in the leaves. The author wishes to thank professor Poul Larsen for advice and criticism. He also gratefully acknowledges financial support from the Agricultural Research Council of Norway.
Absorption of Iron by Enzymically Isolated Leaf Cells
Authors: Kannan S. , Wittwer S. H.
Published: April 2006

Iron uptake was studied using cells enzymically isolated from green tobacco leaves. Absorption was increased both by light and succinate as probable energy sources. Bicarbonate in the incubation mixture was inhibitory, and citrate also reduced absorption presumably by chelation with the metal. Absorption of iron was temperature sensitive and optimal at 25°C. Temperature coefficients and activation energies suggested that absorption was energy mediated. NaN3 and DNP inhibited uptake at concentrations of 10‐3M and 10−4M, respectively. The inhibition caused by DNP was not negated by an external supply of ATP. The results suggest that iron absorption is an active metabolic process in cells enzymically isolated from green tobacco leaves.

Cells from Fe‐chlorotic leaves of PI 54619–5–1 soybean absorbed less iron than those derived from healthy leaves of the same variety, while leaf cells from the variety Hawkeye showed no such differences.
The Oxidising Activity of Roots in Waterlogged Soils
Authors: Armstrong W.
Published: April 2006

Root oxidising activity has been studied quantitatively in two species, Menyanthes trifoliata and Molinia coerulea, using a non‐specific dye technique, and an oxygen‐specific “polarographic” technique in conjunction with artificial roots constructed from silicone rubber tubing.

Oxidising activity in these two species has been found to be up to nine times greater than can be accounted for by oxygen diffusing from the roots. Enzymatic oxidation is thought to be the cause of such high oxidising activity.

The characteristic patterns of iron oxidation found on and around roots are discussed, and oxidation of iron at the rhizophere ‘boundary’ is illustrated.

Earlier work on root oxidising activity is briefly reviewed.
Some Characteristics of Rapidly Labeled RNA in Jack Beau Leaves
Authors: Matsumoto H. , Kobayashi M. , Takahashi E.
Published: April 2006

The characteristics of rapidly labeled RNA in jack bean leaves were investigated. The RNA was prepared by the phenol method and fractionated with methylated serum albumin column. The composition of DNA and ribosomal RNA were also determined. The labeled RNA which appeared after 90 minutes' incubation could be differentiated clearly from the ribosomal RNA by means of the elution pattern and the nucleotide composition. The RNA labeled for 90 minutes disappeared completely after 210 minutes' incubation and the other three peaks appeared at almost the same position as ribosomal RNA.
Marine Plankton Algae Grown with Light‐Dark Cycles. I. Coccolithus huxleyi
Authors: Paasche E.
Published: April 2006

A description is given of an apparatus for semi‐continuous cultivation of unicellular algae under various combinations of light intensity, temperature and daylength (photoperiod). In this apparatus growth of the coccolithophorid Coccolithus huxleyi was limited by light intensities below 0.05 cal/cm2 min regardless of daylength. Growth was retarded by daylengths shorter than 16 hours out of a total of 24 hours of light plus dark. The temperature optimum for growth was about 20 C and showed little variation with daylength. The content of chlorophyll a varied between 2 and 15 mg per ml cell volume and was greatest under low light intensities, short daylengths and high temperatures. Cultures were synchronised by four different combinations of light intensity and daylength. In all four cases, cell division was restricted to 6 out of 24 hours. Synchronised cell division took place in the dark but its timing bore no simple relationship to the onset or termination of illumination.
Metabolism of Indole‐3‐acetaldehyde.
Authors: Rajagopal R.
Published: April 2006

Aerobic infiltration of synthetic indoleacetaldehyde (IAAld) in buffered medium of pH 4.55, into living tissues of lower and higher plants, leads in the majority of cases to the formation of both indoleacetic acid and tryptophol. This activity is evinced by etiolated as well as green tissues. Besides, all parts of higher plants tested — roots, cotyledons, hypocotyls and leaves possess this activity. Abolishment of this activity by boiling indicates its enzymic nature. Coupled with the established occurrence of indoleacetaldehyde, the widespread distribution of such activity, strengthens the probability that indoleacetaldehyde may be the normal and natural precursor in the biosynthesis of indoleacetic acid.
The Salt Absorption Isotherm
Authors: Oertli J. J.
Published: April 2006

It is shown that the absorption isotherm of rubidium by excised barley roots can be explained either by two uptake mechanisms following Michaelis‐Menten kinetics or by two mechanisms, one actively transporting salts into the tissue (the pump), the other one being more passive in nature (the leak), operating in either direction, depending on external and internal substrate concentration. Kinetic data are thus consistent with more than one transport model.

It was further demonstrated for the pair K‐Na, that a competitor not only reduces salt uptake but can also reverse the direction of net flux. This observation cannot be explained by classical enzyme kinetics, it is, however, consistent with the pump and leak system.

Just as Michaelis‐Menten kinetics, the pump and leak system can explain ion competition, in addition it offers a possible explanation of the Viets' effect and it can explain the time curve of absorption.