bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Occurrence of Phytylpyrophosphate and Acyl Esters of Phytol in Irradiated Dark‐Grown Barley Seedlings and Their Possible Role in Biosynthesis of Chlorophyll
Authors: LILJENBERG CONNY 
Published: April 2006

AbstractDark‐grown barley seedlings which had been irradiated for 6 to 8 h have been shown to contain fatty acid esters of phytol. No such esters could be found in non‐irradiated seedlings. The fatty acids were saturated or had only one double bond. The most prominent acid was palmitic acid.Isolated etio‐chloroplasts from non‐irradiated and irradiated barley seedlings also contained phytylpyrophosphate. The ratio of free phytol to phytylpyrophosphate is only little changed when the seedlings are irradiated for 6 to 8 h. The chemical identifications of free phytol and the phytol derivatives are based upon combined gas chromatography/mass spectrometry.
Patterns of Hormones, Respiration and Ripening Enzymes during Development, Maturation and Ripening of Cherry Tomato Fruits
Authors: ABDEL‐RAHMAN M. 
Published: April 2006

AbstractChanges in growth, endogenous levels of hormones, ethylene evolution and cellulytic and pectolytic enzyme activities of cherry tomato fruits (Lycopersicon esculentum Mill. cv. Small Fry) were assayed from anthesis through ripening. After anthesis, growth of cherry tomato fruit follows a three‐dimensional and sigmoid growth pattern which consits of cell division, cell enlargement, mature green, pink and red stages. Cytokinins and auxins were abundant and reached their peak during early development (cell division). Gibberellin levels were more prominent during the period of cell enlargement and reached a peak before the green mature stage. Levels of abscisic acid increased gradually during maturation and reached a maximum in the advanced green mature stage. Respiration pattern was characterized by a climacteric peak at the pink stage. Ethylene production remained less than 2 μl/kg fresh weight an hour until shortly before mature green stage, then rose rapidly to a maximum at pink stage. Activities of cellulytic and pectolytic enzymes were first detected at the green mature stage and increased rapidly during fruit ripening.
Inhibitory Effect of Gibberellins on Archegonial Differentiation in Lygodium japonicum
Authors: TAKENO KIYOTOSHI , FURUYA MASAKI 
Published: April 2006

AbstractArchegonial differentiation in light‐grown gametophytes of Lygodium japonicum was partially inhibited by exogenously applied gibberellin A3 (GA3) at a concentration of 10−6M, and fully prevented at 10−5M. The inhibitory effect was nullified by transferring the GA3‐treated samples onto fresh media omitting GA3, so that the archegonial formation became discernible 6 days after the transplantation. The application of 10−4M GA3 to younger gametophytes brought about a complete inhibition of archegonial differentiation, whereas the same concentration applied to older gametophytes did not influence the process at all, indicating the timing of archegonial differentiation during the ontogeny. Activity spectrum of authentic gibberellins on the basis of concentrations inducing 50% inhibition of archegonial formation was obtained as follows: GA4= GA9 > GA7 > GA3 > GA1= GA5= GA8.
Stimulation of Growth and Nucleic Acid Biosynthesis at Low Concentration of Abscisic Acid in Tissue Culture of Spinacia oleracea
Authors: NEŠKOVIĆ M. , PETROVIĆ J. , RADOJEVIĆ LJ. , VUJIČIĆ R. 
Published: April 2006

AbstractThe effect of abscisic acid on growth, ultrastructure and nucleic acid biosynthesis was studied in tissue culture of spinach (Spinacia oleracea L.). Low concentration (0.01 mg l−1) of abscisic acid increased fresh and dry weight of calluses, whereas 1.0 mg l−1 was inhibitory. The stimulating effect was observed only in the presence of a relatively high concentration of kinetin (1 mg l−1). The inhibitory effect was partly overcome by the same kinetin concentration. The low concentration of abscisic acid probably accelerated the induction of callus growth after subculture and stimulated cell division in the exponential phase of growth.Electron microscopy showed the presence of numerous polysomes and rough endoplasmic reticulum in callus cells grown at the stimulating abscisic acid concentration. Control cells and cells at the inhibitory concentration had slightly hyaline cytoplasm and were more vacuolated.Incubation of callus tissue with 32P in the presence of stimulating concentration of abscisic acid showed a significant increase in the rate of biosynthesis of all nucleic acid classes after 8 h, whereas inhibitory concentration produced a decrease in 32P incorporation. However, when the tissue was grown in the presence of abscisic acid for 20 days, both concentrations decreased the rate of nucleic acid biosynthesis, as compared to the controls.
Growth and Maintenance Respiration in Whole Plants, Tops, and Roots of Lolium multiflorum
Authors: HANSEN G. K. , JENSEN C. R. 
Published: April 2006

AbstractContinuous measurements of CO2‐exchange were separately carried out on tops and roots of small swards of Lolium multiflorum grown in nutrient solution in growth chamber during 3–4 weeks. From these measurements, a daily carbon balance and accumulated dry matter could be established. The data were used to distinguish between two components of respiration, one proportional to growth or photosynthesis (growth respiration), the other proportional to plant dry weight (maintenance respiration).The separation of respiration in the two components was made by multiple regression analyses with daily photosynthesis or growth rate and accumulated dry matter as the independent variables. To ensure independency between the independent variables during the growth period, photosynthesis was varied by application of alternate three‐day periods of high and low irradiance. From the two regression coefficients, the efficiency of converting assimilates into constructive growth (YG) and the maintenance coefficient (M) could be derived.Three experiments with varying length of photoperiod and dark period were carried out. The analyses were carried out for whole‐plant respiration, respiration of tops and respiration of roots separately. Growth respiration for whole plants as well as for tops and for roots was lower — and hence the efficiencies higher — the longer the photoperiods were. Growth respiration and maintenance respiration were higher for roots than for tops. The high rate of root respiration may originate from release of HCO3− in exchange for NO3−. The parameters found can be utilized quantitatively in computer models of crop photosynthesis and respiration.
Levels and Aggregation of Ribosomes during Dormancy and Dormancy Break of Peach Flower Buds
Authors: BAGNI N. , MARINO G. , TORRIGIANI P. , AUDISIO S. 
Published: April 2006

AbstractThe level of ribosomes and their aggregation state (monosomes‐polysomes) have been investigated in relation to dormancy in peach flower buds (Prunus persica). The ribosomes were analysed by a linear sucrose gradient. The ribosomal content hardly changes in the bud before dormancy and until dormancy breaks; on the other hand after this period there is a remarkable increase in the ribosomal level strictly related to the increase in bud weight. The ribosomal content reaches the highest value at flowering. During dormancy break the largest portion of ribosomes is localized in flower primordia, not in scales. Polysomes, which are always present in buds, remain constant during dormancy (35%), increase at dormancy breaking, reaching the highest level at flowering.
Freeze Preservation of Cultured Plant Cells. III. The Pregrowth Phase
Authors: WITHERS LYNDSEY A. , STREET H. E. 
Published: April 2006

AbstractThere is an inverse relationship between cell size and capacity to survive the freeze‐preservation protocol. Pregrowth of cell suspensions in media rendered more negative in water potential by addition of mannitol enhances the survival capacity of Acer pseudoplatanus and Capsicum annuum cells but this effect can only partially be explained in terms of the associated reduction in mean cell size. Studies with cell suspensions of Daucus carota indicate the importance for successful freeze‐preservation of the stage in the growth cycle of suspensions propagated in batch culture; highest survival was recorded for cells taken at lag phase or early exponential phase. Regrowth of recovered cells depends upon the establishment of an appropriate inoculum density of cells which have retained the capacity to divide. The dividing cells only achieve a growth rate equal to that of untreated cells after a number of cell generations. A proportion of the recovered cells giving an initial positive fluorescein diacetate reaction lose this capacity rapidly (within 24 h), others lose the capacity more slowly and others, in which the positive reaction persists, are incapable of division. These observations indicate that different levels of injury are inflicted by the freeze‐preservation protocol and that only in a proportion of the cells is the injury reparable or compatible with growth by cell division.
NADH and NADPH Dependent Malate Dehydrogenases of Phaseolus vulgaris
Authors: VIDAL JEAN , GADAL PIERRE , CAVALIE GERARD , CAILLIAU‐COMMANAY LUCIENNE 
Published: April 2006

AbstractFrench bean (Phaseolus vulgaris L. cv. Contender) leaf extracts catalyse the reduction of oxaloacetate to malate in the presence of NADH and NADPH. Under the experimental conditions used, the optimum pH values are 8 and 6 respectively. After chromatography on diethylaminoethyl cellulose, two principal forms of NADH‐MDH (L‐malate: NAD+ oxidoreductase, E.C. 1.1.1.37) upon which NADPH activities are superposed, can be characterized. This result is confirmed by electrophoresis on polyacrylamide gel. On the other hand, after filtration on Ultrogel 34, NADH‐MDH is eluted as a single peak; once again, NADPH activity is associated with it. When PtCl2−4, a powerful inhibitor of MDH, is added to the reaction medium, the degree of inhibition is the same irrespective of the cofactor employed. When root extracts are submitted to chromatography on diethylaminoethyl cellulose, activity profiles are identical to those obtained with leaves. These results suggest that the NAD dependent enzymes can also utilize NADP to reduce oxaloacetate. After addition of dithiothreitol, another NADPH‐MDH activity manifests itself in the leaf extracts; it differs from the foregoing ones in its optimum pH, its chromatographic properties and its response to PtCl2−4 action. Root extracts do not exhibit this activity thus showing a specific localization of this enzyme in the green part of the plant.
Reduction of Mercury Chloride by Chlorella: Evidence for a Reducing Factor
Authors: BEN‐BASSAT D. , MAYER A. M. 
Published: April 2006

AbstractEvidence is brought for the presence of low molecular weight, heat stable, mercury reducing factors in Chlorella cells. Some of the properties of these factors, which appears to be normal metabolities, are described. These factors are also present in the medium in which the cells grow. The reduced mercury, Hg0, is volatilized from the culture medium more rapidly than Hg+2. The resultant decrease in the Hg concentration appears to be the main reason for the recovery of the cells from Hg stress. No resistance to Hg developed in cells emerging from the stress.
Hypoxic Quiescence in Alligatorweed
Authors: QUIMBY P. C. , KAY S. H. 
Published: April 2006

AbstractPropagules (stem cuttings) of alligatorweed [Alternanthera philoxeroides (Mart.) Griseb.] were subjected to various treatments of submergence, emergence, light, dark, and oxygen to relate hypoxia to the suppression of alligatorweed growth by dark submergence. In the dark, submergence completely inhibited alligatorweed growth. A nitrogen atmosphere inhibited growth from emersed propagules in the dark. The suspension of growth by dark submergence was relieved by light (40 μ einsteins/m2× s photo‐synthetically active radiation), emergence (whereby air is transported to underwater nodes via the aerenchyma), or exposure to 100 mg · l‐1 of hydrogen peroxide solution renewed at 48‐h intervals. Suspension of growth by a nitrogen atmosphere was relieved by inclusion of 16% oxygen in the ambient atmosphere. Dark to light transfers showed that the suspension of growth was immediately relieved if the requisite conditions were restored; this phenomenon, as described, thus appears to be hypoxic quiescence. The suppression of growth of two other amphibious species, mild smartweed (Polygonum hydropiperoides Michx.) and creeping water‐primrose (Jussiaea repens L. var. glabrescens Ktze.), by dark submergence suggests that hypoxic quiescence may be a factor in the life history of amphibious species other than alligatorweed.
Tryptophansynthase in Phycomyces blakesleeanus Teil I: Eigenschaften des Enzyms
Authors: HILGENBERG WILLY , HOFMANN FRIEDER 
Published: April 2006

Abstract Tryptophan synthase in Phycomyces blakesleeanus. Part I: Characterization of the enzyme.Tryptophan synthase was tested in light grown 5 days old cultures of Phycomyces blakesleeanus.The test was carried out only by reaction 3 (indole + serine → tryptophan + water) of the tryptophan synthase. The Km values for the substrates indole and serine were found to be 1.3 × 10‐4M and 1.0 × 10‐2M. Two Km values (1.5 × 10‐8M and 1.0 × 10‐6M) for pyridoxal 5′‐phosphate could be calculated from a Lineweaver‐Burk plot. The transformation of the Lineweaver‐Burk plot into the Hill plot resulted in a straight line with a rise of 0.35 for pyridoxal 5′‐phosphate. At higher concentrations the end product tryptophan and indole‐3‐acetic acid inhibit the tryptophan synthase in vitro.
Ion Uptake in Higher Plants and KCl Stimulation of Plasmalemma Adenosine Triphosphatase: Comparison of Models
Authors: NISSEN PER 
Published: April 2006

AbstractCriteria for the acceptance or rejection of the dual, the cooperative, and the multiphasic model of ion uptake are given and are used to evaluate the models on the basis of previously published analyses. In addition, mathematical representations of the models are fitted to concentration‐dependence data for various ions and plant tissues by a general curve fitting program. The calculated parameters are evaluated for biological relevance, and the fit is compared by statistical analysis. The kinetics of ion uptake in higher plants are found to be consistent with the concept of multiphasic uptake mechanisms, while the dual and the cooperative model must be rejected. KCl stimulation of plasmalemma‐bound ATPases is also shown to obey multiphasic kinetics, thus strengthening the correlation between ion uptake and membrane‐bound ATPases.
Change in Molecular Size of Cellulose during Regeneration of Cell Wall on Carrot Protoplasts
Authors: ASAMIZU TETSUYA , TANAKA KEIICHI , TAKEBE ITARU , NISHI ARASUKE 
Published: April 2006

AbstractProtoplasts isolated from carrot cells were cultured in a chemically defined medium. The majority of them regenerated cell wall and underwent cell division. Cellulose synthesis started without a noticeable lag but the rate of deposition was very low during the initial stage. The degree of polymerization of cellulose was determined by viscosity measurement of the nitrated product. The cellulose formed in the early stage of the wall regeneration consisted mainly of low molecular weight glucan chains. Change in the average molecular weight of cellulose was found during the growth cycle of carrot cells in normal suspension culture.
Alterations in Activity of Phosphatases during the Peridinium Bloom in Lake Kinneret
Authors: WYNNE DAVID 
Published: April 2006

AbstractAcid and alkaline phosphatases have been isolated from Peridinium cinctum f. westii (Dinophyceae) during an algal bloom in Lake Kinneret. Acid phosphatase activity was fairly constant over the entire period of the bloom, although fluctuations in activity appeared to correlate with the chlorophyll content of the cells. Histochemical studies showed that the enzyme was localized inside the cell. Alkaline phosphatase activity was very low until May, a month after the peak of the bloom, when it increased sharply. Polyacrylamide gel electrophoresis revealed one or two bands of alkaline phosphatase that increased in intensity as the bloom progressed. However, the highest activity of the enzyme (in the last sample collected) corresponded to a new, very intense band on the gels. Similarly to acid phosphatase, alkaline phosphatase was also localized inside the cell. The appearance of alkaline phosphatase is probably related to the available phosphate concentration in the lake, although the influence of other factors that may contribute to the induction of the enzyme cannot be ruled out.
Abscisic Acid and Gibberellin‐in Three Ungrafted Apple (Malus sylvestris) Rootstock Clones
Authors: YADAVA U. L. , LOCKARD R. G. 
Published: April 2006

AbstractABA and gibberellin‐like substances were extracted from roots, shoots, and leaves of most dwarfing M9, semi‐dwarfing MM 106, and least dwarfing MM111 apple rootstock plants. Among tissues, the roots contained the largest and the shoots the smallest amounts of all the phytohormones studied. Plants of M9 contained the highest and MM111 the lowest ABA‐like substances in all tissues tested. Gibberellin4+7‐like compounds were at the highest levels in the roots of MM111 and lowest in the roots of M9, whereas GA3‐like substance was in the reverse order. All three gibberellin‐like compounds were highest in the shoots and leaves of MM111 and lowest in the respective tissues of M9 clone. Role of these phytohormones in the dwarfing mechanism is discussed.
Tryptophansynthase in Phycomyces blakesleeanus, Teil II: Tryptophansynthaseaktivität des Pilzes in Abhängigkeit von Lichtbedingungen und vom Zinkgehalt des Kulturmediums
Authors: HILGENBERG WILLY , HOFMANN FRIEDER 
Published: April 2006

Abstract Tryptophan synthase in Phycomyces blakesleeanus. Part II: Activity of tryptophan synthase in Phycomyces blakesleeanus depending on the light and the content of zinc ions in the culture medium Five‐day‐old cultures of Phycomyces blakesleeanus show notice‐able differences in the phenotype, depending on the culture conditions (permanent light, permanent dark, zinc deficiency, zinc sufficiency) and related to the distribution of tryptophan synthase activity between mycelium and sporangiophores. Permanent light and the presence of zinc ions in the medium during culturing have an antagonistic influence on the tryptophan synthase. The activity of the enzyme is being reduced in the sporangiophores and increased in the mycelium by the influence of light, while zinc ions in the culture medium increase the activity in the sporangiophores at simultaneous reduction in the mycelium.The importance of tryptophan synthase and tryptophan for the development of the fungus in relation to the metabolism of indole acetic acid is discussed.
Changes in Ribonuclease Activity and Content of RNA during Dormancy and Growth of Bird‐cherry Buds
Authors: EKELUND R. 
Published: April 2006

AbstractRibonuclease has been extracted from buds of bird‐cherry (Prunus padus L.) by a three‐step method. In step 1 ribonuclease was extracted from the homogenized tissue at pH 6. In step 2 the tissue residue from (1) was extracted at pH 7. In step 3 the tissue residue from (2) was extracted with a buffer of pH 8.5 and containing 0.7 M KCl. The ribonuclease from step 1 and 2 is named soluble and that from step 3 bound ribonuclease. The activity of the soluble ribonuclease was very low in October and increased slowly until March. When the buds sprouted in April the activity of this fraction rose rapidly. The activity of the bound ribonuclease was rather high in October and increased continuously from autumn to spring. RNA accumulated slowly between autumn and spring. The change in activity of the two ribonuclease fractions is discussed in relation to development.
Genotypic Responses to Auxins in Tissue Cultures of Phaseolus
Authors: MOK MACHTELD C. , MOK DAVID W. S. 
Published: April 2006

AbstractResponses of seven Phaseolus genotypes to the four auxins picloram, 2,4‐D, NAA and 1AA, in tissue cultures, were examined. Callus growth was promoted by picloram and the range of effective concentrations for most genotypes was broad. The auxin 2,4‐D also enhanced callus growth, but the range of optimal concentrations was markedly narrower than that of picloram. NAA when supplied at relatively high concentrations gave good growth. IAA was ineffective in supporting callus growth. The differences in 2,4‐D concentrations required for optimal growth and the differential responses to low concentrations (0.04–1.25 μM) of picloram between several genotypes tested were large. These genotypic variations in auxin responses were repeatable and may thus reflect genetic differences.
ADP, AMP and Pi interactions with a (Na++ K++ Mg2+)‐dependent ATPase in sugar beet roots
Authors: LINDBERG SYLVIA , BJÖRKLUND GUN 
Published: April 2006

AbstractA dithiothreitol treated membrane fraction of sugar beet roots contains (Na++ K++ Mg2+)‐ATPase activity. Product inhibition of the ATPase activity was studied. This led to the following conclusions: 1) ADP is a competitive inhibitor to MgATP in presence or absence of Na+ and/or K+. 2) ADP does not interact with the Na or K site. 3) AMP has little influence on the velocity. 4) Little AMP is released, and the ratio between ADP and Pi release is approximately 1. 5) Pi is a weak noncompetitive inhibitor to MgATP. 6) Pi is probably released before ADP from the Enzyme–MgATP complex.
Photosynthesis of Conifers in Relation to Annual Growth Cycles and Dry Matter Production
Authors: FRY D. J. , PHILLIPS I. D. J. 
Published: April 2006

AbstractObservations that deciduous and evergreen conifers growing in Britain show similar annual growth increments, despite marked differences in short‐term growth rates, led to a comparative study of seasonal photosynthetic capacity in established trees of four coniferous species with contrasting growth habits. The photo‐synthetic data were compared with seasonal changes in environmental parameters and chloroplast ultrastructure. The maximum net photosynthetic rates (at 20°C) recorded for Larix leptolepis were higher than those for the evergreen conifers when expressed on a leaf weight basis but not when expressed per unit leaf area. The photosynthetic efficiency of new needles in the evergreen species showed an overall decline from just after needle maturity until just before budbreak in their second season, after which photosynthetic rates recovered temporarily, approaching previous maximum levels. There was no obvious correlation between seasonal photosynthetic efficiency (at 20°C) on the one hand, and daily air, and (30 cm) ground temperatures on the other, and there was no obvious winter suppression of evergreen photosynthetic rates. Evergreen needles showed starch loss and some membrane changes with the onset of winter, but there was no evidence for wintertime chloroplast clumping or membrane disruption.
Interactions of Abscisic Acid, Cytokinin and Gibberellin in the Control of Betacyanin Synthesis in Seedlings of Amaranthus caudatus
Authors: BIDDINGTON N. L. , THOMAS T. H. 
Published: April 2006

AbstractIn de‐rooted seedlings of Amaranthus caudatus L., betacyanin synthesis induced by white light or cytokinin was inhibited by abscisic acid (ABA) or a mixture of gibberellins A4 and A7 (GA4/7). The GA4/7 and ABA effects were additive. Thus ABA inhibited the cytokinin action but had no effect on the gibberellin response.