bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stock‐Scion Interactions of Normal and Fruit Ripening Mutants rin and nor in Tomato
Authors: MIZRAHI Y. , DOSTAL H. C. , McGLASSION W. B. , CHERRY J. H. 
Published: April 2006

AbstractScions of the non‐ripening rin and nor tomato strains (Lycopersicum esculentum Mill.) were grafted on normal understock plants (cv. Rutgers) in an effort to study the influence of roots and vegetative tissue on the ripening behavior of the tomato fruit. Receiprocal grafts of ‘Rutgers’ scions on rin and nor understocks as well as grafted and ungrafted controls were also established. No alteration in the ethylene, and CO2 evolution and color development of either mutant fruits on normal understock or of normal fruits on mutant understock occurred. We suggest that the inability of rin and nor mutant fruits to ripen normally stems either from the presence in mutant fruit of a non‐translocatable ripening inhibitor, or from the absence of a non‐translocatable ripening factor.
Water Stress Induced Alterations of the Stomatal Response to Decreases in Leaf Water Potential
Authors: BROWN K. W. , JORDAN W. R. , THOMAS J. C. 
Published: April 2006

AbstractYoung growth‐chamber‐grown cotton plants were subjected to a series of eight periods of soil water stress, which served as a preconditioning treatment. After preconditioning, water was withheld and changes in the stomatal resistance and leaf water potential were determined and compared with similar well watered control plants.The stomatal response of stress preconditioned plants adjusted such that the diffusion resistance of the lower surface of the leaf did not reach a value greater than 20 s cm−1 until the leaf water potential dropped 14 bars below that required to reach the same resistance on previously unstressed plants. The resistance—leaf water potential relation for the adaxial surface was unaltered by the preconditioning treatment. Adjustment of the osmotic potential of the guard cells on the abaxial surface provides at least a partial explanation of this change in response. The lack of adjustment of stomatal response on the adaxial surface of the leaves was correlated with a lack of adjustment in osmotic potential of guard cells on that surface.
A Brominating and Hydroxylating Peroxidase from the Red Alga Cystoclonium purpureum
Authors: PEDERSÉN MARIANNE 
Published: April 2006

AbstractA particulate enzyme displaying peroxidase activity has been extracted from the red alga Cystoclonium purpureum (Huds.) Batt. The enzyme preparation was shown to contain ferri‐protoporphyrin IX through its formation of formic acid hemochromogen with absorption maxima at 399, 402, 555 and 600 nm. The preparation catalyses the formation of 3‐bromo‐p‐hydroxybenzyl alcohol from p‐hydroxybenzyl alcohol in the presence of H2O2 and NaBr at pH = 5.4. The formation of 3‐bromo‐p‐hydroxybenzyl alcohol was measured by gas chromato‐graphy‐mass spectrometry. At pH = 6.7, 4,5‐di‐hydroxybenzyl alcohol was formed. Addition of homogentisic acid stimulated the formation of dihydroxybenzyl alcohol and suppressed the brominating reaction. Iodide inhibits the enzyme. The results are consistent with a two‐site model of the enzyme.
Influence of Different Cytokinins on the Germination of Lettuce (Lactuca sativa) and Celery (Apium graveolens) Seeds
Authors: BIDDINGTON N. L. , THOMAS T. H. 
Published: April 2006

AbstractThe naturally occurring cytokinins, zeatin, zeatin riboside and dihydrozeatin did not promote the germination of celery (Apium graveolens L.) seeds and 6‐Δ2‐isopentenyladenine (2iPA) and its riboside were only moderately active. Of the synthetic cytokinins, kinetin, kinetin riboside, and the disubstituted urea, N‐phenyl‐N′‐pyridyl urea (NC5392) were moderately active, and 6‐benzyl‐aminopurine (BA) and its derivatives BA riboside and 6‐benzyl‐amino‐9(tetrahydropyran‐2yl)purine (SD8339) were the most active cytokinins tested. 6‐(o‐hydroxybenzyl)aminopurine (hyd‐BA) and its naturally occurring riboside inhibited germination under normally inductive conditions.All the cytokinins examined were more active in promoting germination of lettuce (Lactuca sativa L.) than celery seeds. BA, BA riboside and SD8339 were again the most active cytokinins. In contrast to the results with celery, zeatin and zeatin riboside were highly active. The other cytokinins also showed high activity with the exception of dihydrozeatin, hyd‐BA and hyd‐BA riboside which were less active. Cytokinin ribosides were less active than the corresponding free bases during the early period of the lettuce seed incubation but total germination after 90 h was similar.
Effect of Salinity on the Photosynthesis of the Halophyte Salicornia rubra and Distichlis stricta
Authors: TIKU B. L. 
Published: April 2006

AbstractThe photosynthesis and biomass production of two contrasting species, Salicornia rubra and Distichlis stricta from the same habitat, were studied under different light intensities and osmotic conditions. Application of NaCl increased the biomass and succulence of Salicornia and decreased that of Distichlis. Ethylene glycol, EG mol. wt. 62.07, and 1:1 NaCl‐EG killed Salicornia and affected Distichlis adversely. The CO2 uptake of both the species increased with increasing light intensity and was strongly influenced by the application of NaCl. All concentrations of NaCl stimulated the CO2 uptake of Salicornia, but decreased that of Distichlis. NaCl significantly decreased the light compensation point of Salicornia but had no effect on that of Distichlis. The CO2 efflux of the two species at 4.52 klx was not significantly different. The rate of CO2 uptake of both the species declined with time at all levels of treatment. Salicornia had a more rapid decline in CO2 uptake in absence of NaCl, whereas that of Distichlis was relatively unaffected by it.Although the tissue Na concentration of the two species increased with increasing NaCl concentration in the medium, the increase in Salicornia was 3.0 to 5.5 times greater than that of Distichlis. Increasing NaCl concentration decreased the chlorophyll concentration of Salicornia and increased that of Distichlis. This resulted in higher ratios of photosynthesis/chlorophyll concentration in Salicornia as against lower ratios in Distichlis. The tissue OP (osmotic potential) of both the species decreased with decreasing OP of the medium. In Salicornia the tissue OP decrease was concurrent with an increase in the CO2 uptake, whereas the CO2 uptake of Distichlis declined with decreasing OP of the medium despite a decrease in its tissue OP. It is concluded that Salicornia requires NaCl for its normal development, whereas Distichlis is adversely affected by it. Both species however, are better adapted to osmotic stress due to natural osmotic agents like NaCl, than to the osmotic stress due to artificial osmotic agents like ethylene glycol.
Effect of Time of Nitrogen Application on Amino‐Nitrogen Composition of Roots and Xylem Sap of Apple
Authors: TROMP J. , OVAA J. C. 
Published: April 2006

AbstractApple rootstocks M.7 were given a nitrogen application either in the spring or in the preceding autumn. At the time of the spring application some rootstocks were ringed. During the 50‐day experimental period from bud‐break, shoot growth and the amount of nitrogen incorporated into the new shoots were slightly reduced in the spring‐treated trees and strongly reduced in the ringed trees of both treatments. Roots of unringed autumn‐fertilized trees showed higher levels of total and amino nitrogen than those of similar trees in the spring treatment; to a lesser degree, the reverse held for xylem sap from the stem. Ringing increased the amino‐nitrogen level in the roots, which suggests a reduced translocation rate.The nitrogen treatments led to marked differences in the percentage composition of the amino‐nitrogen fraction of roots and xylem sap. The distribution of amino acids and amides in the roots and that in xylem sap of the same trees was divergent, but arginine and asparagine often were the most important constituents. Aspartic acid was rather abundant in xylem sap. Ringing did not affect the composition of the amino‐nitrogen fraction in the roots quantitatively but increased the proportion of arginine in the sap.The possible relationship between the composition of xylem sap and soluble nitrogen in the roots is discussed. It is argued that especially in spring‐fertilized trees appreciable amounts of nitrogen must be translocated via the phloem in addition to the transport in the xylem.
La perception géotropique dans la coiffe des racines de Lentille
Authors: PERBAL GÉRALD , PERBAL PATRICK 
Published: April 2006

Abstract Geoperception in the Lentil Root Cap.— Previous analysis showed that, in its initial phase, the geotropic response of Lens culinaris L. roots cannot be explained by a simpleaction by sliding, pressure or contact of amyloplasts on a sensitive surface located along the longitudinal wall. In this study another mode of action is tested by considering the following parameters as functions of the roots inclination: (1) the distance (d) which the amyloplasts move; (2) their number of contacts (c̃) with parietal cytoplasm; (3) the variable (sin α) of the transversal component of the statolith weight (&#x004d;̄×g sin α). It is shown that the initial rate of curvature (V̄), at the various angles, is related to the sedimentation of the amyloplasts by the equation V̄=a log bd̄c̄ sin α (where a and b are constants). The results obtained prove that the geotropic stimulation is dependent upon the sine of the angle (α) of the root inclination and explain the sine rule deviation. The role of statoliths is discussed in the light of recent literature on growth inhibitors which are involved in the geotropic reaction.
Light Control of Anthocyanin Biosynthesis in Zea Seedlings
Authors: DUKE STEPHEN O. , NAYLOR AUBREY W. 
Published: April 2006

AbstractEvidence for involvement of two non‐photosynthetic pigments in photoinduction of anthocyanin biosynthesis in the roots and mesocotyls of Zea mays L. seedlings is presented. Short (5 min), low energy (4.5 × 103 J m−2) fluences of red light neither induced anthocyanin synthesis nor enhanced phenylalanine ammonia‐lyase activity in dark‐grown maize seedlings. Little anthocyanin synthesis and no enhancement of phenylalanine ammonia‐lyase activity was induced by continuous far‐red light. Continuous white or blue light induced both anthocyanin synthesis and enhanced phenylalanine ammonia‐lyase activity. These results show that phytochrome alone cannot induce anthocyanin synthesis in maize seedlings. However, a strong phytochrome mediation of white light induced pigment synthesis was demonstrated. This effect was not demonstrable with white light enhanced phenylalanine ammonia‐lyase activity, indicating that phytochrome controls another step in anthocyanin biosynthesis.
Differential Foliar Sensitivity of Soybean Cultivars to Ozone Associated with Differential Enzyme Activities
Authors: TINGEY DAVID T. , FITES ROGER C. , WICKLIFF CARLOS 
Published: April 2006

AbstractSoybean [Glycine max (L.) Merr.] cultivars Dare and Hood were exposed to ozone (980 μg/m3) for 2 h to determine if differences in cultivar sensitivity were associated with differential activation of selected enzymes. The first trifoliate leaves of the cultivars were in similar stages of development (14 days from sowing) when exposed. The ozone treatment increased the activities of glucose 6‐phosphate dehydrogenase, phenylalanine ammonia lyase, polyphenol oxidase and peroxidase above the control in both cultivars within 30 h after exposure. However, the activity of all these enzymes increased several hours sooner in Dare (sensitive) than in Hood (tolerant). Our data suggest that the differential sensitivity of these two cultivars to ozone could be based on the differential ozone induced activation of the enzymes involved in the lesion formation process.
The Growth Physiology of Coleoptiles in Continuous‐Record Vessels: Anomalous Kinetics of Cycloheximide Action on Auxin‐Controlled Growth
Authors: BLACK M. , DHEIDAH M. 
Published: April 2006

AbstractThe interacting effects of auxin and cycloheximide upon the growth of Triticum coleoptiles depends upon the incubation conditions. In the growth vessel developed by Evans and Ray (1969) the action of cycloheximide is severe and the growth kinetics show a rapid nullification of auxin action by the inhibitor; hormone action is also totally prevented by a relatively short period of pre‐treatment with cycloheximide. The kinetics of response to the two substances are quite different when coleoptiles are floating on the test solutions; here, cycloheximide is much less severe in its action. These differences are due to a heightened sensitivity to cycloheximide induced by exclusion of the air bubble from the coleoptile cylinder in the Evans and Ray chamber. The outer surface of the coleoptile wall is a less efficient respiratory surface than the inner one. When coleoptiles are filled with a stagnant solution insufficient oxygen can be taken up through the inner surface and the tissue therefore suffers oxygen deprivation. This exacerbates the action of cycloheximide as a potent respiratory inhibitor. The results raise questions concerning the use of conditions in which coleoptile sections are filled and submerged, which is a feature of recently introduced continuous‐record growth vessels. In particular, interpretation of the interactions between cycloheximide and auxin under such conditions must be made cautiously.
Effects of NaCl Salinity on Nitrogenous Compounds and Proteases during Germination of Vigna sinensis Seeds
Authors: PRISCO JOSÉ TARQUINIO , VIEIRA GUSTAVO HITZSCHKY FERNANDES 
Published: April 2006

AbstractSerido bean (Vigna sinensis (L.) Savi) seeds were sown in water and in NaCl solution of —4.3 bars water potential. Total, insoluble and soluble proteins as well as soluble amino nitrogen and proteolytic activity of cotyledons were studied after 0, 1, 3, 5, 7, and 9 days of germination. Protein breakdown and turnover was delayed by the NaCl treatment as compared to the control. This was not due to the total amount of proteolytic activity, which was unchanged by salinity; even though the specific activity decreased due to the delayed breakdown of proteins under salt stress. The inhibitory effects of salinity on seed protein reserve mobilization may be due more to inhibition of translocation of hydrolysis products than to inhibition of protease activity.
Multiphasic Hexose Uptake in Chlorella
Authors: NISSEN PER 
Published: April 2006

AbstractThe model proposed by E. Komor and W. Tanner for hexose proton cotransport in Chlorella (Planta 123: 195–198. 1975) is shown to be incorrect. Their data cannot represent hexose uptake via a protonated and a deprotonated form of the carrier, but may be precisely represented by a single bi‐ or triphasic mechanism.
Further Characterization of Nitrate and Nitrite Reductases from Chlamydomonas reinhardii
Authors: BAREA J. L. , MALDONADO J. M. , CÁRDENAS J. 
Published: April 2006

AbstractThe enzymes responsible for nitrate reduction in Chlamydomonas reinhardii, namely NADH‐nitrate reductase and ferredoxin‐nitrite reductase, have been further characterized. The first activity of the nitrate reducing complex, NADH‐diaphorase, is protected by FAD against thermic inactivation. This fact suggests an important structural and functional role for this nucleotide in the first moiety of the nitrate reductase complex. The effect of p‐hydroxymercuribenzoate on the diaphorase activity and the protection by NADH against its inactivation indicate that some—SH groups participate in the electron transfer mediated by diaphorase.Radioactive labelling of nitrate reductase with 99Mo and 185W as well as competition experiments between Mo and W indicate that molybdenum is an essential component of terminal nitrate reductase activity. Iron seems to participate in the redox processes mediated by both nitrate and nitrite reductases as suggested by experiments performed at physiological level. Finally a tentative mechanism for the whole process of nitrate assimilation in Chlamydomonas is proposed.
The Effects of Increased Illumination and Shading on the Low‐Light‐Induced Decline in Photosynthesis in Cotton Leaves
Authors: NAGARAJAH S. 
Published: April 2006

AbstractAn experiment was carried out to study whether low‐light‐induced damage to the photosynthetic system in leaves of cotton (Gossypium hirsutum cv. Deltapine) which are below the compensation point in the canopy can be arrested and reversed by increased illumination. In addition it was intended to find out whether the photosynthetic system in leaves of shade plants show a greater resistance to low‐light‐induced damage than leaves of plants from more exposed habitats.The plants were grown at high density, and increased illumination to the shade leaves in the canopy was achieved by thinning the stand. Thinning was carried out at two stages and its effects on the decline in the photosynthetic capacity of the 4th leaf were followed. An early thinning was carried out shortly after the 4th leaf dropped below the compensation point and a late thinning 2 weeks later. Comparison was also made between the low‐light‐induced damage to the photosynthetic capacity of the 4th leaf in plants grown under two light regimes during the progressive increase in self‐shading of the 4th leaf within the canopy.It was observed that both types of thinning arrested the low‐light‐induced damage to the photosynthetic system in shade leaves. The decline in photosynthetic capacity of the 4th leaf was stopped after both early and late thinning. The dry weight of the shoot system in the early and late thinned plants was not significantly different. It was double that of the control plants. The plants thinned early did not have higher shoot weight than the late thinned plants since there was a rapid shedding of flowers and fruits after early thinning. The 4th leaf in the early thinned plants showed a 30% increase in chlorophyll content and dry weight per unit leaf area. It is suggested that shedding of flowers and fruits, and increases in chlorophyll and dry weight per unit leaf area in the early thinned plants were caused by a change in the hormonal balance of the plants.The photosynthetic system in leaves of shade plants showed a greater resistance to damage by low light intensity than the photosynthetic system in leaves of plants grown at higher light intensities.
The Effect of Zinc on the Formation of Ribulose Diphosphate Carboxylase in Phaseolus vulgaris
Authors: JYUNG WOON H. , CAMP MARY E. 
Published: April 2006

AbstractThe effect of Zn on the formation of ribulose diphosphate carboxylase (RuDPCase was investigated in the leaf discs from Zn‐deficient Sanilac navy bean plants (Phaseolus rulgaris L.). The incorporation of 14C‐leucine into the partially purified RuDPCase was found to be a quantitative equivalent of the level and activity of the enzyme. Zn as ZnSO4 at 10 uM stimulates the formation of RuDPCase by at least 2‐fold. Neither CuSO4 nor CdSO4 at the same concentration substitutes for ZnSO4. The enhancement of RuDPCase formation by added Zn is greater with increasing severity of Zn deficiency, suggesting that Zn is a limiting factor in this system. Suppression of the Zn‐stimulated formation of RuDPCase by actinomycin D and cycloheximide suggests that the Zn‐mediated formation of RuDPCase most likely represents de novo synthesis. Also, the possible site(s) of action of Zn is discussed.
Effect of Water Deficit on the Growth of Squash Fruit
Authors: COCUCCI S. , COCUCCI M. , TRECCANI C. POMA 
Published: April 2006

AbstractThe growth of squash fruit was followed in the field under normal and drought conditions. The following phenomena were observed: a) under drought conditions the fruit growth is normal in the night while it becomes more and more reduced with progress of time in the daylight period; b) the decrease of growth capacity in the daylight period does not correspond to a dehydration of the fruit tissues and it is accompanied by a conversion of polysomes to monosomes; c) the water deficit also causes a decrease of RNA and protein content in the fruit tissues, but this situation does not affect the rate of growth in the night. The data suggest that under conditions the fruit growth is controlled by water availability through protein synthesis; under ample water supply, water availability or some other factor, rather than RNA and protein level, is limiting the fruit growth.
An Electrical Analogue to Simulate the Oxygen Relations of Roots in Anaerobic Media
Authors: ARMSTRONG W. , WRIGHT E. J. 
Published: April 2006

AbstractThe paper describes the construction and the theory underlying a simple electrical analogue which may be used to simulate the internal oxygen relations of roots in the wetland condition. The model represents an unbranched root lying within an oxygen sink and consists of twenty circuit units linked in series. Each unit which can be programmed independently, represents the major oxygen diffusion paths, impedances and sinks recognizable in a centimetre‐long segment of root/wet soil system. Simplicity has been achieved by specifying constant radius for the root (0.05 cm), constant potential activity for the external sink, by expressing respiration and radial oxygen loss as a function of root surface area, and by the non‐inclusion of oxygen storage capacity.
Localization and Activity of a Carboxypeptidase in Germinating Seeds of Scots Pine, Pinus sylvestris
Authors: SALMIA M. AULIKKI , MIKOLA JUHANI J. 
Published: April 2006

AbstractExtracts prepared from the endosperm of germinating seeds of Scots pine, Pinus sylvestris L., hydrolysed two typical carboxypeptidase substrates, Z‐Phe‐Ala and Z‐Phe‐Phe, with pH optima at 4.2 and 5.0. The activities were completely destroyed by diisopropylfluorophosphate. Identical heat inactivation curves and elution patterns in gel chromatography on Sephadex G‐200 suggest that the two activities are due to a single enzyme.In resting seeds very low carboxypeptidase activity was present in both the endosperm and the embryo. During germination on agar gel at 20°C in the dark the activities, expressed as enzyme units per seed, increased in the seedling and particularly in the endosperm up to the stage when the reserves of the endosperm were completely depleted. The time of rapid increase of activity in the endosperm did not coincide with the onset of storage protein mobilization. On the contrary, the major part of the increase occurred after the bulk of endosperm nitrogen had already been transferred to the seedling.The results suggest that the carboxypeptidase does not play a major role in the mobilization of storage proteins in germinating pine seeds. On the other hand, it probably functions in the proteolytic reactions associated with the senescence of the reserve‐depleted endosperm.