bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanism of Antifungal Action of 2,4,5,6‐Tetrachloroisophthalonitrile
Authors: Vincent Phillip G. , Sisler H. D.
Published: April 2006

Studies of the toxicity of 2,4,5,6‐tetrachloroisophthalonitrile (TCIN) to cells of Saccharomyces pastorianus and Neurospora crassa showed that 2 to 4 μg/ml of the toxicant were required to inhibit growth. Several thiol compounds reversed toxicity to growth.

Glucose oxidation was severely impaired in treated cells of both test organisms. The toxicant at 2 or 4 μg/ml markedly reduced soluble thiol content of these cells. Bound thiol content was less affected in S. pastorianus cells than soluble thiol content.

Uptake of toxicant by yeast cells was accompanied by formation of derivatives, some of which resembled those formed by reaction of glutathione with TCIN in vitro. Coenzyme A, glutathione, and 2‐mercaptoethanol readily formed derivatives with TCIN in vitro. The nature of these derivatives was studied using 2‐mercaptoethanol products as model substituents. Four derivatives were formed with 2‐mercaptoethanol each with similar functional groups but showing dissimilar degrees of mobility during silica gel chromatography. Evidence indicated that these are derivatives of TCIN in which 1 to 4 of the halogens has been substituted by 2‐mercaptoethanol.

The mechanism of fungicidal action of TCIN is attributed to thiol inactivation.
Effect of Ethylene on Peroxidase Activity
Authors: Gahagan H. E. , Holm R. E. , Abeles F. B.
Published: April 2006

Ethylene increased the peroxidase activity of nine out of ten varieties of sweet potato (Ipomoea batatas (L.) Lam.) root disks tested. The increase which was observed four hours after ethylene treatment was partially overcome by carbon dioxide. The increase was inhibited by actinomycin D and cycloheximide, indicating de novo protein synthesis. Electrophoretic separation on polyacrylamide gels indicated the appearance of two new peroxidase bands. Peroxidase activity in bean petiole explants was localized around the separation layer. Ethylene caused a small increase in peroxidase activity in the petiolar portion of the explant. Phenolic substances had no effect on abscission consistent with their proposed roles as cofactors for auxinoxidase, indicating that auxin‐oxidase does not play a role in abscission of Coleus blumei Benth. abscission zone explants.
Dynamic Modifications in Alfalfa Leaves Growing in Subtropical Conditions
Authors: Gindel I.
Published: April 2006

In upper Galilee a field of alfalfa was sown in April 1965 in order to study the influence of the quantity of irrigation on leaf structure and on yield. Three treatments were given, each on five experimental plots: 1) Irrigation, with 5000 m3 per ha; 2) Irrigation with 10,000 m3 per ha; and 3) non‐irrigated. Leaves were picked four times during 1965/66, each time after the field had been cut and after the regrowth had developed. The following conclusion can be drawn from the results. Each regrowth shows changes in the number of stomata and epidermis cells, in the length of stomata, and in leaf area as a result of the three treatments and of the changing environmental factors during the period of development of the four regrowth leafages.

The greatest modification was noted in the non‐irrigated experimental plots of highest stomata density; the least modification in plots with 1000 m3 per ha irrigation.

The results show that there is a relationship between modification of stomata and changes in edaphic and climatic factors.
Changes in Individual Nucleotides of Developing Soybean Seeds
Authors: Galitz Donald S. , Howell Robert W.
Published: April 2006

Perchloric acid extracts of soybean seeds were separated by column chromatography into 17 peaks. Thirteen nucleotides were identified in 11 of these peaks (NAD, CMP, CDP, CTP, AMP, ADP, ATP, GMP, GDP, GTP, UMP, UDP, and UTP). Two of the peaks were identified as ascorbic acid and dehydroascorhic acid. Four peaks remain unidentified although one of these appears to be protein.

Monophosphates decreased and triphosphates increased as development proceeded. Diphosphates were initially low and showed no statistically significant difference with maturity.

The accumulation of triphosphates in late stages of development is discussed in relation to synthetic activities of the developing seeds.
Dark‐Germination of Reciprocal Hybrid Seed from Light‐Requiring and ‐Indifferent Nicotiana tabacum
Authors: Kasperbauer M. J.
Published: April 2006

Seed resulting from self‐fertilization of Nicotiana tabacum plants was tested for germination in uninterrupted darkness at monthly intervals beginning at time of harvest. All seed lots were light‐requiring immediately after harvest. Some lots continued to be light‐requiring, but others gradually became light‐indifferent during storage under laboratory conditions. One light‐requiring and one light‐indifferent selection were self‐pollinated, and reciprocally crossed. The seed resulting from self‐fertilization was light‐requiring or light‐indifferent, respectively, according to the parentage. Seed resulting from the reciprocal crosses differed in dark‐germinability. Further, dark‐germination of seed from each of the reciprocal crosses differed from that of either parent. Both parents contributed toward light sensitivity of the seed; however, contribution of the maternal parent was greater than that of the pollen parent.
On the Physiology of Zoospore Production in Aphanomyces astaci
Authors: Unestam Torgny
Published: April 2006

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

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

The effect of the tissue age of dark‐grown bean plants on the chlorphyll formation under continuous illumination or short impulses of white light has been studied. It was found that the protochlorophyllide present in the tissue is age‐dependent and reaches a plateau at about 10 days of age, as judged by the chlorophyll formed in etiolated plants of various ages after 5 min illumination.

The amount of chlorophyll a and chlorophyll b formed under short impulses of while light increases up to about 9 days of age and thereafter decreases. However, the decrease in chlorophyll a is sharper than that of chlorophyll b, the amount of which remains almost constant.

The ratio of chlorophyll a lo chlorophyll b under the short impulses of white light is higher in the younger plant. Similar results are obtained after transfer of the plants from the flashing light to continuous illumination In the young plant there is no lag phase in the chlorophyll biosynthesis while as the age is increased the lag phase is evident and its duration increases as the plant ages.

After protochlorophyllide phototransformation under continuous illumination the lag phase in chlorophyll biosynthesis is also age‐dependent. Leaves up to 5 days old show no lag phase in chlorophyll synthesis; after this point, however, the lag phase's duration increases continuously with age.
An Asymmetric Respiratory Response Occurring when Fluoride and Copper Ions are Applied Jointly to Chlorella vulgaris
Authors: Hassall Kenneth
Published: April 2006

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

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

The ability of pine pollen to grow in vitro is discussed in relation to its in situ. Optimal conditions of growth in vitro were investigated. All the experiments were made with pollen of Pinus mugo Turra.

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

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

Three varieties of wheat. Thatcher, Falcon and Sunset. were grown under 20. 12 or 8 hour days until the initiation of spikelet primordia on the shoot apex began, and then in natural light until maturity. Phosphorus (100 mg/l P) was applied at 7, 33 or 54 days after sowing, other plants were left without phosphorus. The response of the plants to phosphorus in terms of final leaf number, grain production and number of fertile spikelets was related to time of initiation.

When the time of initiation was 52 or more days after sowing there were some responses in grain yield to phosphorus, but they were independent of time of application; for initiation times of 32 days or less the earlier applications of phosphorus tended to give a greater response.
Isoenzyme Changes during Seed Germination of Saguaro Cactus (Carnegiea gigantea)
Authors: Keswani C. L. , Upadhya Mahesh D.
Published: April 2006

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

Zygotes obtained by self‐fertilization of Allomyces macrogynus, strain Burma 3 and of A. arbuscula, strain Ceylon 1, behave chemotactically as do their respective zoospores. All the swarmers respond to an equimolar mixture of L‐leucine and L‐lysine with the response enhanced by the addition of L‐Proline. The A. arbuscula swarmers also respond moderately to a mixture of L‐proline with certain amino acids other than leucine and lysine whereas those of A. macrogynus do not.

The gametes are not chemotactically responsive to the amino acids. Within no more than five minutes subsequent to fertilization, the zygotes become chemotactically active.

The genetically‐derived, approximately 95 % male or female isolates do not appear to form zygotes when crossed. The few zygotes observed in a series of attempted crosses appear to be the result of selfing by the contaminating opposite sex in each of the highly unisexual strains.
Auxin Physiology of Dwarfism in Pisum sativum
Authors: Lantican Beatriz P. , Muir Robert M.
Published: April 2006

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

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

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

Soluble ribonucleic acid of brewer's yeast was fractionated by countercurrent distribution and assayed for certain amino‐acid acceptor activities, as well as for cytokinin activity, using both tobacco pith callus tissue and Scorzonera crown‐gall tissue.

An undetermined fraction of ribonucleic acid, rich in cytokinin and similar to one previously reported for baker's yeast, was observed. Two species of cytokinins, probably different from isopentenyl adenine, were detected in other ribonucleic acid fractions by comparing their activities on the two tissues used in growth tests. They do not seem to be located in any of the specific amino‐acid accepting transfer ribonucleic acids determined in this study.
Photomorphogenic and Chlorophyll Studies in the Bryophyte Marchantia polymorpha
Authors: De Greef J. , Fredericq H.
Published: April 2006

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

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

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

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

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

The contents of some forms of phosphorus (lipid, soluble, phytin, nucleic) were investigated in grain of wheat, variety “Mara”.

The plants were grown in water culture using a Reid‐York nutritive solution. After 15 or 30 days one of the following elements was eliminated: nitrogen, phosphorus, sulphur, calcium or magnesium.

The results show that the phosphorus contents of the different forms were lower in grain from the field than in that from the water cultures. The deficiency of the individual elements during vegetation affected the grain weight and the contents of the investigated forms of phosphorus, which fact indicates that different mineral nutrients have different effects on the metabolism of phosphorus.
The Suppression of Stareh Synthesis and the Accumulation of Uridine Diphosphoglucose in Cucumber Leaves due to Ammonium Toxicity
Authors: Matsumoto H. , Wakiuchi N. , Takahashi E.
Published: April 2006

This work is a study of the metabolic disorder due to ammonium toxicity in cucumber (Cucumis sativus L. cv. suisei No. 2) leaves. The cucumber was cultured with 20 and 200 mg/l NH3‐N for 5 days. In the first half of this experiment, the plant leaves were photosynthesized for 3 hours to study the distribution of 14C in starch and other fractions. The incorporation of photosynthesized 14C into not only starch but also other higher polymers was suppressed by ammonium toxicity. On the other band, the rate of 14C incorporation in 80 % ethanol soluble fraction was higher in the treatment of 200 mg/l NH3‐N. In the latter half of experiment, phosphate esters in the loaves were analyzed by column chromatography. The opposing contents of uridine diphosphoglucose (UDPG) and the uridine compound containing sugar or sugar derivative (UDPX) were determined by different ammonia levels. Toxicity of ammonia resulted in an increase of UDPG and a decrease of UDPX. The level of ATP was not changed so much. The content of glucose‐6‐phosphate (G‐6‐P) in injured plants was lower than that of normal plants, while ghicose‐1‐phosphate (G‐1‐P) and fructose‐6–phosphate (F‐6‐P) were higher in injured plants. These results further suggested the disorder of carbohydrate metabolism due to ammonium toxicity which was reported previously.
A Model of the Photosynthesizing Leaf
Authors: Brown K. W.
Published: April 2006

A model is proposed for the relationship between net photosynthetic rate (N) and light Intensity at a given concentration of CO2 in the air ([CO2]a). The model provides a prediction of the sum of the diffusion resistances (Σr), the capacity (K) of the leaf to fix CO2, the concentration of CO2 at the point of photosynthesis ([CO2]g), and the respiration rate (R). The model fits the available data well and provides a frame work by which future research may be guided.

The calculated values of [CO2]g decreased from [CO2]g at the compensation point to a nearly constant value at high tight intensities. [CO2]g high light infensitit‐s range from 32 to 144 μ/l (volume) depending on the species. When these values of [CO2]g, are used in the diffusion equation, the resulting levels of the mesophyll resistance (rm) are lower than those calculated by using the assumptions that [CO2]g equals zero. The plants which had (he higher photosynthetic rates at a given light intensity and [CO2]a had grealer values of [CO2]g than those with lower photo‐synthetic rates.

The calculated rates of respiration of wheat leaves were twice as high as those measured in the dark. This suggests that the light respiration rate may be twice as great as the dark respiration rate at the same temperature.

The calculated values of K demonstrate variability within and between species. The maximum N was independent of K. A relationship between K and the maximum quantum efficiency, at constant levels of [CO2]g, was demonstrated in several species.

The Σr was inversely related to the maximum rate of photosynthesis for the species investigated. The values of rm calculated for cotton were inversely related to [CO2]a suggesting that the transfer of [CO2] in the cell may involve a concentration dependent chemical reaction in addition to or rather than a physical diffusion process.
Auxin Synergists in Rooting of Cuttings
Authors: Basu R. N. , Bose T. K. , Roy B. N. , Mukhopadhyay A.
Published: April 2006

Leafy cuttings of Eranthemum tricolor were treated with tannic acid, gallic acid, p‐hydroxybenzoic acid and salicylic acid at the concentrations of 1000, 100, 10 and 1 nig/1 for 24 hours, whereafter they were dipped quickly in a 1000 mg/l solution of IAA, IBA and NAA for ten seconds.

None of the phenolics showed any root promoting effect when used singly. In combination with NAA and IBA tannic acid promoted rooting, however, with IAA there was no effect to be seen. Gallic acid also markedly increased the number of roots of cuttings treated with NAA and IBA. Even in this case there was no effect with IAA.

Synergism was also recorded between p‐hydroxybenzoic acid and IAA or NAA but not with IBA.

Salicylic acid greatly promoted rooting in combination with both IAA, IBA and NAA.
Mechanism for the Uptake of Zinc by Fontinalis antipyretica
Authors: Pickering D. C. , Puia I. L.
Published: April 2006

The rate of uptake, the effects of carrier ions, temperature, light intensity and dinitrophenol (DNP) upon the uptake of zinc (using zinc‐65 as tracer) by Fontinalis antipyretica were investigated. The absorption medium contained 0.5 mW CaSO4 and the pH was kept constant using boric acid and sodium hydroxide as buffer.

About 50 per cent of the zinc absorbed at equilibrium was taken up in the first half hour, Analysis by semi‐log plot procedures showed that, at least, three sections may be distinguished in the uptake curve, suggesting that three successive processes (stages) were involved. The first stage was very short, and not influenced by temperature, light intensity and DNP. The second stage, lasting no more than 90 minutes, mi very slightly affected by the same three factors. In this stage freshly killed plants absorb more zinc than living material. The third stage, lasting several days, was very slow and was light, temperature and DNP dependent.

Based on these findings, a mechanism for zinc uptake is proposed.
Non‐Reversibility of Gibberellin‐Induced Inhibition of Regeneration in Begonia Leaves
Authors: Heide Ola M.
Published: April 2006

With applied to the petioles of detached Begonia x cheimantha leaves before planting, Gibberellic acid (GA3) inhibited the formation of adventitious buds and roots ill an apparently irreversible manner. Bud formation was entirely suppressed by 10−6M and higher concentrations and a significant inhibition was still present at 10−9M the lowest concentration tested. Root formation was not affected by GA3 below 10−7M and was possible even at 10−4 M GA3. Petiole elongation was stimulated by GA3 with an optimum at 10−5M.

GA3 also blocked the action of 6‐benzyiamino‐purine (BAP) and 1‐naphthaleneacetic acid (NAA), compounds which are potent stimulators of bud and root formation, respectively. When applied simultaneously with GA3 they were, at their optimal concentrations, devoid of any effect in counteracting or reversing the gibberellin‐induced inhibitions. Abscisic acid and the growth retardants CCC and Phosfon also were unable to restore bud and root formation.

In leaves initially treated with water or 10−5M BAP, endogenous bud and root formation as well as BAP‐induced bud formation were entirety suppressed when 10−5M GA3 was applied 8 days after the initial treatments. Even when delayed for 14 days GA3 treatment inhibited BAP‐induced bud formation, while treatment after 21 days bad little effect on bud and root formation. Development of pre‐existing, visible bud primordia was not inhibited by GA3.

BAP and NAA competitively inhibited the action of GA3 in petiole extension growth.

The results are discussed in relation to results obtained in other plant systems. It is suggested that GA3 acts by blocking of the organized cell divisions initiating the formation of bud and root primordia.
The Demand for Iodine and Bromine of three Marine Brown Algae grown in Bacteria‐free Cultures
Authors: Pedersen Marianne
Published: April 2006

Three marine brown algae have been cultivated with different additions of iodine and bromine in bacteria‐free cultures. Ectocarpus jasciculatus appeared to have an absolute demand for iodine and was inhibited by a concentration of 64 μmol of KJ per 1. Lithosiphon pusillus had the best growth in the highest concentration tested (64 μmol/1) but there was always some growth in the series without iodine. Additions could be made either as inorganic iodine or as organically bound iodine. Additions of KJ to a culture medium consisting of vitamin‐free Asp 6 F with B12 (1 μg/1) and kinetin (20 μmol/1) remarkably increased the growth of the zoospores of Pylaiella litoralis.

Lithosiphon pusilius proved to be indifferent to bromide additions in media containing KJ. In media lacking KJ addition of 1 μmol of KBr per 1 is stimulating but higher concentrations of KBr are inhibiting. The inhibiting effect is overcome by iodide addition.
Effect of Sucrose and Gibberellic Acid on Floral Induction of Xanthium
Authors: Mukherjee Ilabanta
Published: April 2006

Application of gibberellic acid (GA3) before and sucrose after the inductive dark period promotes flowering in Xanthium. The promotive effects of these two compounds are independent but additive. Sucrose application either before or utter the dark period has promotive effect on the flowering response. These effects are additive. The roles of pre‐ and post‐induction high‐intensity light period and of GA3 in the promotion of flowering have been discussed. It has been suggested that sucrose application promotes flowering by increasing translocation of the flowering stimulus and by promoting the rate of development of the terminal male inflorescence. It has also been suggested that GA3‐induced promotion of flowering is due to the increased synthesis as well as translocation of the flowering hormone.
Effect of Gibberellic Acid on the Elongation Rate of Agrostis alba Root Hairs
Authors: Devlin Robert M. , Brown Daniel P.
Published: April 2006

The influence of gibberellic acid over a wide range of concentrations on the rate of elongation of root hairs of redtop grass was investigated. The rate of root hair elongation was increased by GA over the concentration range of 10−7 to 10−12 M inclusive, with peak stimulation occurring at 10−6 M. Although root hair growth was slightly accelerated by 10−6 M GA, this concentration damaged many root hairs and caused some to stop growing altogether. Rate of root hair elongation was reduced to less than 84% of the control by 10−5 M GA.
Ribonuclease in Leaves of Phaseolus vulgaris during Maturation and Senescence
Authors: Phillips D. R. , Fletcher R. A.
Published: April 2006

The levels of the enzyme ribonuclease (RNase) were determined in primary leaves of Phaseolus vulgaris in an attempt to correlate changes in RNA with maturation and senescence. RNase, RNA and chlorophyll levels increased in expanding and maturing tissue and subsequently declined in senescing tissue. Senescence of the primary leaves started with the onset of flowering. A simultaneous increase of RNA and RNase in maturing tissue and a decrease during senescence suggests that the enzyme activity is correlated with the rate of‘turnover’of RNA rather than the absolute levels of RNA present in the tissue.
Phytochrome Control of Nyetinasty in Samanea as Modified by Oxgen, Submergence, and Chemicals
Authors: Sweet Haven C. , Hillman William S.
Published: April 2006

Samanea saman has rapid phytochrome‐regulated nyctinasty: red light preceding darkness causes pinnules to close while far‐rod light allows opening‐ Not only the initial angle of the pinnules, but the degree of control by phytochrome depends on the “subjective time of day” at which the tissue is exposed. Excised pairs of pinnules close rapidly when submerged in water; such closure is prevented by bubbling oxygen through the water. However, if submergence closure were due solely to low oxygen levels, then nonsubmerged pinnules in a pure nitrogen atmosphere should also close. Instead, they neither close nor respond to light, but they do respond when air is readmitted, indicating that oxygen is necessary for movement rather than for photoreception. The closure of submerged pinnules remains unexplained. Attempts to detect effects of red or far‐red on oxygen uptake by pulvinus tissue were unsuccessful.

The following method has been used to test the effects of various inhibitors and other substances: pinnules are excised at the first hour of the day, trimmed, submerged in a sealed chamber, given far‐red light, and left in darkness while oxygen is bubbled through the medium. Concentrated test solutions are injected either initially or when the red and far‐red exposures are given. Thus far, the substances tested have had little or no effect on the phytochrome response.
Malonate Metabolism, Stimulation of Conidiation and Succinate Dehydrogenase Activity in Neurospora crassa
Authors: Ojha M. N. , Velmelage R. , Turian G.
Published: April 2006

Malonate was studied for its effect on succinate dehydrogenase activity and conidiation. It Was found to stimulate the succinate dehydrogenase activity and also conidiation of Neurospora crassa.

The efficiency of sucrose metabolization for cellular synthesis was improved in malonate supplemented cultures. High Concentration (0.5 M) had a distinct toxic effect on conidiation and economic efficiency. Teratological structures were observed at 0.5 M malonate concentration.

A stimulation of the glyoxylate cycle is considered to be one of the factors responsible for the conidiogenic effect.
Der Einfluss verschiedener Salze und verschiedener Inhibitoren auf den Wurzeldruck von Zea mays
Authors: Mengel K. , Pflüger R.
Published: April 2006

The effect of different salts and inhibitors on the root pressure of Zea mays.— The influence of various salt solutions and inhibitors on the exudation rate has been investigated with young excised primary roots of Zea mays. The following results were obtained. — The effect of chlorides on the exudation rate was higher than the effect of sulphates K+ and Na+ effected higher flux rates than Ca2+ and Mg2+ The highest exudation rate was obtained with KCl. — In comparison to an isotonic Lutrol‐solution (a liquid condensed polyethylenoxid) a 0.5525 molar KCl‐solution, applicated on the root stump, increased the exudation rate considerably. — Metabolic inhibitors and anaerobic conditions decreased the exudation rate. — Experiments, concerning the influence of metabolic inhibitors on the exudation and on the Rb‐uptake showed a highly significant positive correlation (r =+0.72***) between the exudation rates and the Rb‐concentrations in the exudates. The Rb‐accumulation in the root tissue was not correlated to the exudation rate. — The experimental data agree with the concept of a transversal water transport in the root tissue, effected by osmotic forces. The root pressure is based on the osmotic gradient between the xylem sap and the outer solution. This gradient is built up by the metabolic secretion of ions into the xylem sap. It is supposed that the transversal water transport in the roots mainly goes through the free space of the cortex.
The Effect of Nonanal on Dipodascus aggregatus IV. Studies with Different Carbon Sources
Authors: Nyman Brita
Published: April 2006

Nonanal (80 μ) in ethanolic solution stimulated the growth of Dipodascus aggregatus with fructose (55.5 mM) as carbon source (inoculum grown with fructose or glucose). If the inoculum had been grown with galactose, neither growth with galactose nor growth with glucose was affected by nonanal. If the inoculum had been grown with glucose, growth with galactose was weakly. stimulated. —Growth with galactose (galactose‐grown inoculum) was strongly stimulated by nonanal if xylose at a low concentration (0.53 mM) was added. — The oxygen uptake of glucose grown cells with glucose as substrate was stimulated by 200 μM nonanal in the absence of ethanol. The respiratory activity of galactose‐grown cells was also stimulated with galactose as well as with glucose as substrate. In the absence of exogenous substrate the oxygen uptake of glucose‐grown cells was weakly stimulated by nonanal whereas that of galactose‐grown cells was strongly stimulated.
The Effects of Auxins, Amino Acids, and Catechols on the Formation of Red Pigment in Helianthus tuber slices
Authors: Suzuki Yonezo , Kanamori Tetsuo
Published: April 2006

The mechanism of red pigment formation in tuber slices of Helianthus tuberosus during incubation with auxins has been studied and the following results were obtained. 1. The degree of expansion of the tissue slices in the presence of indole‐acetic acid (IAA), 2,4‐dichloropbenoxyacetic acid (2,4‐D), or α‐naphthaleneacetic acid (NAA) was not parallel to the colour intensity which developed during incubation. 2. The pigment solutions which were extracted by pyridine. ethanol, or dioxane commonly showed a peak at around 515 nm in the absorption spectrum. 3. The o‐diphenol oxidase activity in the tissue slices was increased by incubation with 2.4‐D. 4. I.‐Proline or hydroxy‐L‐proline as reactants in the formation of red pigment by the o‐diphenol oxidase system could not be replaced by L‐arginine, L‐histidine and L‐tryptophan. 5. The red pigment may resemble 4‐(4′‐hydroxy‐2′‐carbethoxy ‐1′‐pyrrolidyl)‐5‐methyl‐o‐benzoquinone, formed by the o‐diphenol oxidase system in the presence of homocatechol and hydroxy‐L‐proline.
Studies in Physiological Analysis of Yield. IX, Effect of Light Intensity on the Development of the Wheat Grain
Authors: Asana R. D. , Parvatikar S. R. , Saxena N. P.
Published: April 2006

Under average tight intensities, 57,800 (sunlight, L), 12,900 (l1), 3900 (12) and 3300 (13) lux, during the fortnight after anthesis, the increase in the average shoot weight (excluding roots) of wheat cultivars, NP 823 and NP 824, varied as 100, 43, 24 and 10, and of cultivars, Ph C 281 and NP720, as 100, 35, 15 and 9; the corresponding increase in weight of ear varied as 100, 59, 45 and 40, in the first group and as 100, 58, 53 and 33, in the second. The increase in ear weight was relatively less affected by low light intensity than increase in shoot weight, probably because the stem‐sugars were utilized in grain‐filling. The stem‐sugars increased only in L and decreased in 11, 12 and 13. The grain number and its weight were also reduced under l1, 12 and l3. Assuming that increase in shoot weight is a measure of photo‐synthetic activity, it is inferred that during the fortnight after anthesis, current photosynthesis determines largely, but not entirely, the rate of growth of grain. After transfer to full sunlight, the grain weights of l1, 12 and 13 plants amounted, at maturity, to 93, 78 and 77 % of the value of L. The actual increase in grain weight was the same in L and l1 and slightly lower in l2, and 13. It is inferred that the same amount of photosynthate was produced in all the four treatments hut was not fully utilized in 12 and 13 because of considerable reduction in grain number. Since the sugar content of the stem in l1, I2 and l3 plants, on the 15th day after anthesis, was half as much as, or even lower than, in L, whereas the increase in grain weight was much less affected, it follows that the level of stem‐sugars does not determine the rate of growth of grain. During the fortnight before maturity, light intensity as low as 2500 lux had little effect on grain development. It is concluded that light intensity equal to that of full sunlight may not be required during the entire course of grain development. Considering that sugars accumulate in the stem during the fortnight after anthesis, and their concentration does not control the subsequent rate of growth of the grain, it is suggested that a more efficient sink (ear) may be the means by which photosynthates can be more effectively utilized and the yield potential raised further.
Regulators of Cell Division in Plant Tissues VUI. The Cytokinins of the Apple Fruit
Authors: Letham D. S. , Williams M. W.
Published: April 2006

The cytokinin activities of extracts of organs developed from the apple fruit bud were compared using the carrot phloem bioassay, and the identity of the cytokinins in the apple fruitlet was investigated. The activity of apple fruitlet extracts was slightly greater than the activity of pedicel extracts, and considerably greater than the activities of extracts of other organs. Extracts of the developing seeds of fruitlets were much more active than extracts of fruitlet flesh. Apple fruitlet extracts contained three principal cytokinins. One was identified as a 6‐(substituted amino)purine and was either zeatin or some very closely related compound. The two other cytokinins exhibited the chromatographic behaviour of zeatin riboside and zeatin ribotide. A cytokinin extracted from vegetative apple shoots was chromatographically indistinguishable from zeatin.
Isoenzyme Polymorphism in Flowering Plants. IV. The Peroxidase Isoenzymes of Maize (Zea mays)
Authors: Hamill D. E. , Brewbaker J. L.
Published: April 2006

Twenty‐four peroxidase isoenzymes were identified by starch gel electrophoresis of 250 varieties of maize. Twelve of these bands corresponded in electrophoretic mobility to bands observed in commercial horseradish peroxidase. Maize tissues varied greatly in isoenzyme pattern, many tissues having a characteristic and distinguishing complement. Ontogenetic variations were observed for the leaf blade, leaf sheath, and internodes during maturation, and were related to the rates of tissue enlargement. Genetic studies of two isoenzymes, C10 and C20, indicated that they were conditioned by alleles of a single locus, here designated Px1.