bluuebunny/crossref_metadata_2025_split huggingface dataset:
Balance between Cyanide‐Sensitive and ‐Insensitive Respiration in Wheat Root Mitochondria, as Influenced by Salt Concentration in the Plant Growth Medium
Authors: MØLLER I. MAX 
Published: April 2006

AbstractMitochondria were isolated from 7‐day‐old wheat roots (Triticum vulgare Vill. cv. Svenno Spring Wheat) grown in either a full‐strength culture medium (100%) or in the same medium diluted 100 times (1%). Outer membrane integrity was assayed using the cytochrome c reduction assay. This indicated about 20% damage. Using an oxygen electrode the respiration of the mitochondria was measured with either malate or succinate as the substrate (both 40 mM). KCN (3 mM) and salicylhydroxamic acid (SHAM, 1 mM) were used as inhibitors. The properties of the isolated mitochondria (STATE 3 rate, ADP/O ratio, and KCN‐sensitivity) depend upon the ionic concentration of the growth medium of the roots. In the mitochondria isolated from roots grown in the 1% medium (1% mitochondria) there is a synergistic effect of KCN and SHAM. This means that electrons can be shifted from one pathway to the other when only one of the inhibitors is added. This flexibility between the electron pathways is almost nil in the mitochondria isolated from roots grown in the 100% medium (100% mitochondria). The maximal capacity of the alternative electron pathway (= rate in the presence of KCN) is higher in 1% (40 nmol O2 min−1 (mg protein)−1) than in 100% mitochondria (20 nmol O2 min−1 (mg protein)−1. In 100% mitochondria the alternative pathway seems to be operating at maximal capacity in the absence of KCN with both substrates and in both STATES 3 and 4. In 1% mitochondria the alternative pathway functions at >50% of its capacity in the absence of KCN.
Respiration of the Roots of Flood‐Tolerant and Flood‐Intolerant Senecio Species: Affinity for Oxygen and Resistance to Cyanide
Authors: LAMBERS HANS , SMAKMAN GERARD 
Published: April 2006

AbstractThe affinity of respiration for oxygen in the roots of six Senecio species studied was low compared with the affinity of cytochrome oxidase for oxygen. Half saturation values of approximately 22 μM oxygen were measured. Root respiration was to a large extent insensitive to cyanide in flood‐tolerant as well as in flood‐sensitive species. The evidence presented suggests that high activity of salicylhydroxamic acid (SHAM)‐sensitive oxidase in Senecio roots was the basis for the low oxygen affinity and for the high cyanide‐insensitivity of root respiration in the Senecio species. Methods are described to determine the in vivo activity of the SHAM‐sensitive oxidase. It was estimated that it contributed 70% to the total root respiration.The presence of SHAM‐sensitive oxidase activity could explain a higher efficiency of root growth respiration under a low oxygen tension if this alternate oxidase was inhibited at a low oxygen concentration in the root medium. However, the SHAM‐sensitive oxidase was not specifically involved in either growth respiration or maintenance respiration. Its significance in regulation of the redox state of the cells is discussed.
Efficiency of Root Respiration of a Flood‐Tolerant and a Flood‐Intolerant Senecio Species as Affected by Low Oxygen Tension
Authors: LAMBERS HANS , STEINGRÖVER EVELIENE 
Published: April 2006

AbstractA method was described to determine root growth respiration and root maintenance respiration rate of plants, grown in culture solutions of high and low oxygen concentrations, during linear growth. Root growth respiration of aerobically grown plants was three to four times lower in the flood‐intolerant Senecio jacobaea L. than in the flood‐tolerant species. Senecio aquaticus Hill. Root growth respiration of Senecio aquaticus Hill decreased by a factor two to three upon transplantation to a culture solution of low oxygen tension. The difference in root growth respiration between aerobically and anaerobically grown Senecio aquaticus Hill was ascribed to the presence of a highly active non‐phosphorylating oxidase.
Nitrogen Nutrition and Cytokinin Activity in Solanum tuberosum
Authors: SATTELMACHER B. , MARSCHNER H. 
Published: April 2006

AbstractIn water culture experiments with potato plants (Solanum tuberosum L. cv. Ostara), the influence of continuous nitrogen nutrition (constant supply of NO3−) and discontinuous nitrogen nutrition (interruption of NO3− supply, i. e., nitrogen withdrawal for 6 days) on the endogeneous cytokinin level in the roots, shoots and exudate of decapitated plants was studied. Harvests took place at intervals of 3 days. The chlorophyll formation test (cucumber cotyledons) and soya callus test were used to determine the cytokinin activity.With continuous nitrogen, the cytokinin activity decreased slightly with time in both roots and shoots but rose in the exudate. With discontinuous nitrogen, the nitrogen withdrawal led to a temporary, pronounced increase in cytokinin activity in the roots; at the same time, the cytokinin activity in the exudate decreased sharply. It is assumed that this temporary increase in cytokinin activity in the roots is a reflection of increased meristem activity in the roots. In the shoots, the cytokinin activity decreased during the nitrogen withdrawal period. These nitrogen‐induced changes in cytokinin activity in the roots and shoots of potato should presumably have an important influence on the physiological age of the shoot, with all its consequences in the further development of the plant. Zeatin riboside was likely the main cytokinin component involved.
Characteristics of Zinc Uptake by Barley Roots
Authors: VELTRUP WERNER 
Published: April 2006

AbstractThe linear uptake of zinc by excised barley roots (Hordeum distichon L.) in the time range from 20–120 min is not continued over periods of 20–28 h. In concentration dependent uptake experiments with intact barley roots three phases in the range up to 1.38 mM zinc could be detected independent of the tested uptake period. The kinetic constants increased with higher phases and the transition points were lowered with increasing time. The presence of copper did not inhibit the uptake of zinc competitively. On the contrary a slight stimulation in the uptake rates was observed indicating an interaction with the transition site. It is concluded that zinc and copper are taken up by separate mechanisms.
Influence of Ammonium on the Growth and Development of Suspension Cultures of Pauľs Scarlet Rose
Authors: MOHANTY BIBEKANANDA , FLETCHER JOHN S. 
Published: April 2006

AbstractIn this work as in previous studies from this laboratory it was demonstrated that the presence of a trace amount of NH4+ (72.8 μmol) stimulated the growth of Pauľs Scarlet Rose on a defined medium containing NO3− (1920 μmol) as the only other source of nitrogen. A kinetic analysis of several growth parameters showed that the rate of increase of dry weight, fresh weight, cell number, and cell volume were greater during early stages of growth (days 0–8) when NH4+ was provided. During later stages (days 8–14) this relationship between the two cultures did not hold. The cells provided NH4+ continued to increase in fresh weight and cell volume, but the cells which were not provided NH4+ had a greater rate of dry weight and cell number increase. These differences led to 14‐day‐old cultures which were approximately equal in dry weight and cell number but differed by a factor of 2 in fresh weight. The presence of NH4+ speeded up the development and growth of the cells.
Rhythmic Production of CO2 by Tropical Orchid Flowers
Authors: HEW C. S. , THIO Y. C. , WONG S. Y. , CHIN T. Y. 
Published: April 2006

AbstractCircadian rhythm of CO2 production was observed in some tropical orchid flowers. The tight bud showed relatively low respiration and no rhythmic changes. As soon as the flower opened, respiration increased and rhythmicity became apparent. The period for the rhythm was about 24 hours. Dark treatment and detachment dampened the amplitude of the rhythm without affecting the rhythmicity. In depollinated and pollinated flowers, the rhythmicity was less pronounced. Pollination and depollination appeared to stimulate respiration at the trough of the cycle. However, there was no significant difference in respiration per day between the untreated and treated flower. Both pollination and depollination hasten the senescence of orchid flowers.
Influence de la benzylaminopurine sur ľabsorption du phosphate par des disques de tubercules de pomme de terre
Authors: PENOT ANNICK HOURMANT et MICHEL 
Published: April 2006

Abstract The Influence of Benzylaminopurine on the Absorption of Phosphate by Potato Tubers Aging of disks of potato tuber in an aerated liquid medium induces a large increase of the rate of phosphate absorption. Experiments were performed with benzylaminopurine added to the aging solution at various times after slicing, and the rate of absorption was determined 24 h after slicing. The opposite experiment was also performed, with benzylaminopurine added at the beginning and withdrawn after different times. The addition of benzylaminopurine to the aging medium partially prevents the development of the phosphate uptake. The uptake mechanism is a metabolic phenomenon as shown by its sensitivity to temperature. The degree of inhibition depends on the benzylaminopurine concentration as well as on the time of aging. The results suggest that the cytokinin acts on a process which occurs all along the aging and underline the importance of the presence of benzylaminopurine during the first hours of aging.
A Method for the Isolation of Stable Mesophyll Protoplasts from Tomato Leaves throughout the Year under Standard Conditions
Authors: CASSELLS ALAN C. , BARLASS MARTIN 
Published: April 2006

AbstractA method is described, based on growing tomato plants under low light intensities and feeding with calcium nitrate, whereby stable protoplasts can be isolated throughout the year under standard conditions. Plants are grown in the equivalent of spring and winter light intensities (i. e. incoming solar radiation 2.52 to 10.8 MJ m−2 day−1 15 h day) in the glasshouse on peat compost supplied with a balanced fertilizer containing nitrate and urea as nitrogen sources and given a supplementary feed of calcium nitrate. Under these conditions, high yields of protoplasts can be isolated on incubation in the dark using low enzyme concentrations at 25°C for 2 h. Protoplasts isolated in this way can support tobacco mosaic virus replication and are capable of cell division.
Characterization of the Proteinases Present in Germinating Seeds of Scots Pine, Pinus sylvestris
Authors: SALMIA M. Aulikki , NYMAN SEIJA A. , MIKOLA JUHANI J. 
Published: April 2006

AbstractMethods were developed to determine proteinase activity in germinating seeds of Scots pine. The assays were based on the liberation of TCA‐soluble peptides from haemoglobin at pH 3.7 and from casein at pH 5.4 and pH 7.0; the reaction products were determined by the Lowry method. — Endosperms separated from seeds at the time of rapid storage protein mobilization (seedling length between 20 and 50 mm) showed high proteinase activities in all three assays. Experiments with different inhibitors suggested that at least four enzymes were involved. One of the enzymes resembled mammalian and microbial pepsin‐like acid proteinases: the pH optimum was 3.7 and the enzyme was inhibited by pepstatin.—The proteinase activities in the endosperms were high enough to account for the mobilization of the reserve proteins during germination. Moreover the activities at pH 3.7.5.4. and 7.0 in the endosperms were 10‐, 25‐, and 50‐fold the corresponding activities in the growing seedlings (a “reference” tissue). Consequently, it seems that both the acid and neutral proteinases take part in the mobilization of storage proteins in the germinating seed.
Non‐histone Proteins Associated with Chromatin of Spirogyra during the Conjugation Process
Authors: SASAKI KIMIKO 
Published: April 2006

AbstractNon‐histone proteins were isolated from purified chromatin of Spirogyra sp. at different stages of the life cycle. Conjugation‐ specific acidic proteins were separated by DEAE‐Sephadex A50 column chromatography. The protein fraction includes an inhibitor of chromatin‐directed RNA synthesis.
Effects of Water Stress and Hardening on the Internal Water Relations and Osmotic Constituents of Cotton Leaves
Authors: CUTLER J. M. , RAINS D. W. 
Published: April 2006

AbstractExperiments were designed to test the hypothesis that the internal water relations of leaves are altered when cotton plants (Gossypium hirsutum L.‘Acala SJ‐2′) are conditioned by several cycles of water stress. Preliminary experiments suggested that plants so conditioned are less sensitive to water deficits and that the change might be partly explained by an accumulation of solutes or by structural alterations attendant on development under conditions of water stress.Leaves of preconditioned plants maintained turgor to lower values of water potential than did leaves of well‐watered plants. Accompanying this change was a lower osmotic potential at any given leaf water content in preconditioned plants. Tissue analysis of several osmotically active solutes indicated that soluble sugars and malate accumulate to about the same levels (dry‐weight basis) in both conditioned and unconditioned plants exposed to stress. These accumulations could not account for the turgor change. Analysis of the data on relative water content indicated that the leaves of conditioned plants had less water per unit dry weight than did leaves of controls. This change accounts for a substantial fraction of the difference between the osmotic potential of conditioned and control plants. The results of a simple model suggest that structural changes may play a significant role in explaining differences in the responses of conditioned and control plants to water stress.
The Capacity of Various Detergents to Solubilize and Stabilize Protochlorophyll(ide) Holochrome
Authors: STUMMANN B. M. 
Published: April 2006

AbstractEarlier work has shown that protochlorophyll(ide) holochrome is associated with the prolamellar body membranes in etioplasts of barley (Hordeum vulgare L.), and that this pigment‐protein complex can be extracted in a stable, photoactive form by the use of saponin. For future work it would be advantageous if saponin, a detergent mixture, could be replaced by a single, well‐characterized substance. The spectral characteristics of holochrome extracted with 10 ionic and nonionic detergents were compared to those of the holochrome extracted with saponin. Mulgofen BC‐840 and digitonin extracted significant amounts of photoactive protochlorophyll(ide) holochrome, but this activity was highly labile, and no adequate substitute for saponin was found. Thus the stabilizing and solubilizing function of saponin is not simply related to the general properties of detergents.
Multiphasic Uptake of Amino Acids by Barley Roots
Authors: SOLDAL TROND , NISSEN PER 
Published: April 2006

AbstractConcentration‐dependence and other characteristics of uptake of 3H‐labeled l‐lysine, l‐methionine and l‐proline by excised roots of barley (Hordeum vulgare L.) were studied. Use of relatively short uptake and wash periods and low solute concentrations ensured good estimates of influx across the plasmalemma.Uptake in the range of 10−7M– 6.3 × 10−3M can be precisely represented by four or five phases of single, multiphasic mechanisms. The mechanisms appear to be relatively specific as judged from the competition by unlabeled analogues. Structural requirements for interaction of a compound with the uptake site for methionine are given, as are the effects of analogues on the phase pattern for this amino acid. There is no indication of separate uptake and transition sites for methionine or lysine. i.e. phase transitions seem in this case to be caused by binding of molecule(s) to the uptake site.Uptake, but not phase patterns, was highly pH‐dependent. The optima were pH 5 for lysine, pH 3–5 (a broad peak) for methionine and about pH 5.5 for proline. Uptake of the three amino acids was strongly inhibited by 2,4‐dinitrophenol. sulfhydryl reagents and deoxycholate.
The Effect of Potassium on Cotyledon Expansion Induced by Cytokinins
Authors: GREEN JEROME F. , MUIR ROBERT M. 
Published: April 2006

AbstractPotassium has been found to enhance greatly the expansion response of cucumber cotyledons to cytokinins. A reduction of the response to kinetin is obtained with increasing age of the cotyledons. The lesser response is associated with lower levels of potassium remaining in the cotyledon. A high level of KCI in the incubation medium offsets the lower potassium content of the tissue and enables a much larger response to the cytokinins. At 40 mM KCI the response to kinetin is 4.2 times greater than in the absence of KCI. Calcium increases the effect of potassium on the response to kinetin. When incubated in 40 mM KCI and 10 mM CaCI2 with 10 mg/I 6‐benzylamino‐purine, the final weight of the cotyledons is 6.8 times the initial weight after just 4 days. This KCI‐CaCI2 combination is also found to promote chlorophyll synthesis in the usual cucumber cotyledon bioassay.
Growth Respiration of a Flood‐Tolerant and a Flood‐Intolerant Senecio Species: Correlation between Calculated and Experimental Values
Authors: LAMBERS HANS , STEINGRÖVER EVELIENE 
Published: April 2006

AbstractRoot growth respiration of Senecio aquaticus Hill (flood‐tolerant) and Senecio jacobaea L. (flood‐sensitive) was calculated, assuming different P: O ratios. The growth respiration values were calculated on the basis of the chemical composition of root and shoot dry matter, in combination with published data on the energy costs of biosynthetic and transport processes. The comparison between calculated and experimental values suggests a relatively low efficiency of ATP utilization in the roots of the flood‐tolerant species.Root growth respiration of S. congestus (R.Br.)DC., which is also flood‐tolerant, and Plantago lanceolata L. were also determined. The data showed that not all the flood‐tolerant species investigated had high root growth respiration values.An “overflow model’ is proposed to explain observed differences in root growth respiration between species.
The Effect of Cadmium on Net Photosynthesis, Transpiration, and Dark Respiration of Excised Silver Maple Leaves
Authors: LAMOREAUX ROBERT J. , CHANEY WILLIAM R. 
Published: April 2006

AbstractExcised leaves of silver maple (Acer saccharinum L.) exposed to 0, 0.045, 0.090, or 0.180 mM Cd24 exhibited reduced net photosynthesis and transpiration, and increased dark respiration. Rates of net photosynthesis and transpiration diminished with time and were strongly correlated with solution concentration and tissue content of Cd24, Net photosynthesis and transpiration were reduced to 18 and 21%, respectively, of the untreated controls after 64 h. Dark respiration increased as much as 193% of the untreated controls but was poorly correlated with solution concentration or tissue content of Cd24, Diffusive resistances of leaves to carbon dioxide and water vapor transfer increased with both increasing Cd24 concentration and time. These findings are discussed in relation to stomatal function.
In vitro Protein Synthesis by Polyribosomes of Peach Flower Buds at Different Physiological Stages
Authors: TORRIGIANI P. , MARINO G. , BAGNI N. 
Published: April 2006

AbstractThe in vitro phenylalanine incorporation by polyribosomes of peach flower buds (Prunus persica Stokes) during dormancy, dormancy break and flowering was investigated. Protein synthesis was measured using as catalyst either calf liver soluble factors or the ribosomal supernatant from the peach flower buds in the presence or the absence of the synthetic mRNA, polyuridylic acid. In the presence of polyuridylic acid, the activity of protein synthesis of dormant ribosomes is the same as that of ribosomes during dormancy break and flowering. The absence of synthetic messenger did not cause a change in activity. The ribosomal supernatant of dormant buds, but not of flowering buds, reduces the phenylalanine incorporation by polyribosomes from buds harvested at dormancy break.
The Effect of Mercaptoethanol on the Activity of Enzymes of Nitrogen Metabolism in Leaves from Urtica dioica and Spinacia oleracea
Authors: WELANDER MARGARETA 
Published: April 2006

AbstractThe effect of mercaptoethanol at different concentrations on enzyme activity was investigated in leaves from Urtica dioica and Spinacia oleracea. The interference of mercaptoethanol with enzyme activity is dependent on the type of plant, the configuration of the enzyme and the concentration of mercaptoethanol. A stimulation of GDH (glutamate‐dehydrogenase) was obtained in both species, while inhibition of GOT (glutamate‐oxaloacetate transaminase) and GPT (glutamate‐pyruvate transaminase) was demonstrated in Spinacia. The stimulation of GOT and GPT activity in Urtica was probably due to inhibition of phenol oxidase. Conclusions concerning the effect of mercaptoethanol on NR (nitrate reductase) activity were difficult to draw, since mercaptoethanol itself reduced nitrite and interfered with NR determination in tests in vitro. In Urtica. no activity could be obtained at all with the in vitro method, probably because an inhibitor of NR was liberated during the extraction procedure, Activity of NR could however be obtained in both species when using the in vivo method. Addition of protective agents to the extraction medium has been supposed to influence the protein extractability. In conformity with this increasing amount of fresh matter to the same volume of extraction medium resulted in decreased protein extractability. This led to differences in enzyme activity when expressed on a fresh weight basis but the specific activity remained constant.
Rhythmic Behavior in Germination of Cocklebur Seeds
Authors: SATOH SHIGERU , ESASHI YOHJI 
Published: April 2006

AbstractNon‐dormant, lower seeds of cocklebur (Xanthium pensylvanicum Wallr.) germinated with unimodal flush after 20 and 36 h from the start of water imbibition at 33 and 23°C, respectively. At 28°C, however, germination occurred bimodally, the time of each peak coinciding with that at 23 and 33°C. This type of germination behavior was induced even at 33°C, when the seeds were contacted with some osmotica. Further, the application of different osmotica at 28°C caused a rhythmic multimodal germination with a period of about 16 h. It was suggested that an endogenous rhythmicity may be involved in the control of cocklebur seed germination.
Control of Chlorophyll Degradation in Detached Leaves of Barley and Oat through Effect of Kinetin on Chlorophyllase Levels
Authors: SABATER B. , RODRGUEZ M.a T. 
Published: April 2006

AbstractChlorophyllase seems to be responsible for the degradation of chlorophyll during senescence of detached leaves of barley (Hordeum vulgare) and oat (Avena sativa). Treatment at temperatures higher than 40°C — which protects against chlorophyll loss — lowers the level of chlorophyllase. Kinetin treatment lowers the level of chlorophyllase in barley leaves and prevents its rise in oat leaves after their detachment. Synthesis of proteins in both cytoplasm and chloroplast seems to be required in order to maintain a high level of Chlorophyllase in barley leaves after detachment.