bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal variation in ribulose bisphosphate carboxylase activity in Pinus silvestris
Authors: GEZELIUS KERSTIN , HALLÉN MONICA 
Published: April 2006

AbstractRibulose bisphosphate carboxylase activity was examined in Pinus silvestris L. during successive seasons. The enzyme activities were studied both in seedlings, kept under controlled conditions in a climate chamber, and in needles from a 15‐year‐old tree in a natural stand. The enzyme activities were analysed in cell‐free extracts prepared with Tween 80 as protective agent.The carboxylase activity fluctuated periodically both in the seedlings and in the natural stand. In the seedlings, the weight‐related activity in the older needles increased 50–100% (in the cotyledons c. 200%) in the beginning of the “summer”. It decreased as the new shoot developed. The specific activity increased c. 100%. With chlorophyll as base, the activity usually decreased during “summer”. In the developing current needles the carboxylase activity increased when expressed on a weight or on a protein basis. The decrease in weight‐related carboxylase activity in the older needles was preceded by, or simultaneous with, loss of total protein. It is suggested that protein, including the carboxylase, is utilized as nitrogen reserve for the new shoot. During hardening by combined photoperiod and thermoperiod, the carboxylase activity decreased when expressed relative to dry weight and protein. Calculated on a chlorophyll basis, the activity was rather constant.In the natural stand the activity in the one‐ and two‐year‐old needles increased during spring and summer and decreased during autumn and winter. Even at severe winter stress substantial carboxylase activity remained in the needles. The activity of the enzyme in vivo is discussed with respect to electron transport and net photosynthesis.
Differentiation in Lilium bulbscales grown in vitro. Effects of activated charcoal, physiological age of bulbs and sucrose concentration on differentiation and scale leaf formation in vitro
Authors: TAKAYAMA SHINSAKU , MISAWA MASANARU 
Published: April 2006

AbstractOrgan differentiation and growth of tissue cultured bulbscales of Lilium auratum Lindl. was investigated. Benzyladenine stimulated bulb and bulbscale differentiation but inhibited root formation. Addition of activated charcoal to the medium negated the effect of BA on differentiation, while the growth of bulbs was markedly stimulated. Organ formation was also influenced by the physiological age of bulbs. From bulbscales of a 3‐week‐old bulb, a large number of bulbs and roots was formed but callus was not produced.A high sucrose concentration (90 g/1) reduced the subsequent sprouting after planting in soil. Scale leaf formation was also regulated. Sucrose (30 g/1) stimulated scale leaf formation but 90 g/1 were inhibitory.
Inhibitors of endogenous proteinases in the seeds of Scots pine, Pinus sylvestris
Authors: SALMIA M. AULIKKI , MIKOLA JUHANI J. 
Published: April 2006

AbstractExtracts of resting pine seeds inhibited the proteinase activities present in extracts of endosperms of germinating seeds (hydrolysis of haemoglobin at pH 3.7 and hydrolysis of casein at pH 5.4 and 7.0). Heating the extracts of resting seeds at 60°C destroyed their own proteinase activity but their proteinase inhibitor activity decreased by only 25 to 30%. Some properties of the inhibitor(s) were studied using extracts treated at 60°C. The inhibitor activities were non‐dialysable. the inhibition increased linearly with increasing inhibitor concentration up to 80% of total proteinase activity, and the maximal inhibition was 80% at pH 3.7. 90% at pH 5.4. and 97% at pH 7.0.The extracts of resting seeds did not inhibit the pepsin‐like acid pine proteinase that accounts for a minor part of the proteolytic activity of endosperm extracts at pH 3.7. Neither did they have any effect on the acid pine carboxypeptidase or trypsin and chymotrypsin.Fresh extracts of endosperms of germinating seeds contained relatively high proteinase activity (assayed directly) and moderate inhibitor activity (assayed after treatment at 60°C). When fresh extracts were dialysed at 50°C for 48 h their proteinase activities increased considerably while the corresponding inhibitor activities disappeared. It is concluded that the decrease of inhibitors during dialysis is due to enzymatic inactivation and that the corresponding increase of proteinase activities is at least partly due to the destruction of the inhibitors.
Water stress and root formation in pea cuttings
Authors: RAJAGOPAL VELAMOOR , ANDERSEN A. SKYTT 
Published: April 2006

AbstractEleven day old pea plants (Pisum sativum L. cv. Alaska), grown at 16 W m−2 or 38 W m−2 were stressed with different concentrations of polyethyleneglycol (PEG): –3.0 (mild), –6.4 (moderate) or –13.9 bar (severe) for 2, 4 or 6 h. The leaf osmotic potential, ψπ, and the endogenous abscisic acid (ABA) level and ethylene production were determined at the end of the stress treatment.The ψπ decreased with stress treatments. The reduction was greater at 38 W m−2 than at 16 W m−2; severely‐stressed plants had less ABA content than those under moderate or mild stress. Ethylene production was higher with the 2 h stress treatment than the non‐stressed only at 38 W m−2. Prolongation of stress to 6 h decreased the ABA level and also ethylene production under both levels of irradiance.The relationship between the changes in ABA and ethylene and the adventitious root formation in pea cuttings is discussed.
The effects of temperature and inhibitors of protein biosynthesis on the recovery from gas‐shock of Acer pseudoplatanus cell cultures
Authors: THOIRON BERNARD , THOIRON ARLETTE , ESPEJO JOSÉ , GUIEL JEANNE LE , LÜTTGE ULRICH , THELLIER MICHEL 
Published: April 2006

AbstractThe resumption of solute uptake capacity lost after gas‐shock of Acer pseudoplatanus L. cell suspension cultures is severely inhibited by low temperatures (1°C) and by inhibitors of transcription and translation of protein synthesis such as 2‐mercapto‐1 (β‐4‐pyridethyl) benzimidazole (MPB, 40 μg ml−1), puromycin (around 100 μg ml−1) and actinomycin (100 μg ml−1). Cells that have already attained maximum uptake capacity loose it again after less than 1 h in 40 μg ml−1 MPB. Gel‐electrophoresis of the external media of the cells shows that the release of proteins into the solution is affected by shock. The results demonstrate that proteins are involved in the mechanism of solute uptake by the cells, so that these proteins are among the factors altered during shock and recovery, and are important for the understanding of the after‐effects of shock.
Fractionation by centrifugation of leaf proteins in press juices from Brassica and other species as a function of pH
Authors: LUNDBORG TOMAS 
Published: April 2006

AbstractNon‐green leaf protein concentrates can be produced after separation of chlorophyll‐associated proteins from chlorophyll‐free proteins by sedimenting the chlorophyll‐containing membranes suspended in press juice. To make the use of low speed centrifugation possible, the influence of pH on protein sedimentation rate was investigated, especially for Brassica Oleracea (17 cultivars). Press juices produced on a laboratory scale from greenhouse grown plant material were adjusted to the desired pH and centrifuges briefly at 5000 g or 15,000 g. The chlorophyll‐associated protein from B. Oleraces sedimented rapidly at pH values both below and above 6.0(original pH of the press juice). When the pH of the press juice was adjusted to 7.5, all the chlorophyll‐associated protein sedimented at 15,000 g, whereas about 45%of the original protein remained in the supernatant. An increase in sedimented chlorophyll‐associated protein at higher pH was also observed for Brassica napus, Helianthus annuus and Vicia faba, but not for Beta vulgaris and Dactylis glomerata.Theoretically, the protein sedimentation pattern typical for B. oleracea might depend primarily on protein aggregation, but shrinking of thylakoids at pH values higher than 6 could contribute. The deviation from this pattern observed for B. vulgaris and D. glomerata might be caused by differences in composition of proteins or low molecular species. In practice, a pH above 7.0 seems to be useful for separation of chlorophyll‐associated proteins from chlorophyll‐free proteins by centrifugation of press juice from Brassica species without heat treatment.
Multiphasic uptake of potassium by barley roots of low and high potassium content: Separate sites for uptake and transitions
Authors: NISSEN PER 
Published: April 2006

AbstractIn the range 10−6M ‐ 5 × 10−2M uptake of K+ in excised roots of barley (Hordeum vulgare L. cv. Herta) with low and high K content could in both cases be represented by an isotherm with four phases. Uptake, especially in the range of the lower phases, was reduced in high K roots through decreases in Vmax and increases in Km. Similar data for other plants are also shown to be consistent with multiphasic kinetics. The concentrations at which transitions occurred were not affected by the K status, indicating the existence of separate uptake and transition sites. Uptake was markedly reduced in the presence of 10−5M 2,4‐dinitrophenol, especially at low K+ concentrations, but the isotherms remained multiphasic. This contraindicates major contributions from a non‐carrier‐mediated, passive flux. A tentative hypothesis for multiphasic ion uptake envisions a structure which changes conformation as a result of all‐or‐none changes in a separate transition site. The structure is “tight” at low external ion concentrations (low Vmax. low Km. active uptake, allosteric regulation) and “loose” at high concentrations (high Vmax‐ high Km‐ facilitated diffusion, no regulation).
Photosynthetic CO2 fixation in spinach chloroplasts inhibited by pine chloroplasts or extracts of pine chloroplasts
Authors: MARTIN BJÖRN , BASSHAM JAMES A. 
Published: April 2006

AbstractChloroplasts isolated from pine needles were found to be inactive with respect to CO2 fixation. Since it was suspected that pine needles may contain substances inhibitory to photosynthesis, studies were carried out using photosynthetically active isolated spinach chloroplasts and chloroplasts isolated from pine needles. When isolated pine chloroplasts were suspended in buffer and were added to isolated spinach chloroplasts they inhibited photosynthetic CO2 fixation. When the pine chloroplasts were separated from the medium by centrifugation, the separated pine chloroplasts severely inhibited CO2 fixation by isolated spinach chloroplasts, but the supernatant solution from the pine chloroplasts was not inhibitory. As little as 5% pine chloroplasts (based on chlorophyll content) produced 50% inhibition of CO2 fixation by the spinach chloroplasts. Studies of fixation of 14C‐labelled CO2 by spinach chloroplasts were carried out in which after 5 min photosynthesis the pine chloroplasts were added. It was found that the subsequent inhibition of spinach CO2 fixation was neither due to any effect on the rate of export of photosynthetic metabolites from the chloroplasts to the medium, nor to a direct effect on the RUBP carboxylase reaction. The principal effect was found to be an inhibition of the conversion of fructose‐1,6‐bisphosphate and sedoheptulose‐1,7‐bisphosphate to the respective monophosphates and inorganic phosphate. From this finding it was concluded that a principal effect of the inhibition by pine chloroplasts is probably an inhibition either directly or indirectly of the bisphosphatase enzymes in the spinach chloroplasts. Based on its distribution between organic and aqueous acidic or neutral solutions, the inhibitory factor of the pine chloroplasts must be lipophilic. Most of the factor could be transferred to an aqueous phase in a strongly alkaline solution. Following subsequent acidification of the aqueous phase the activity could be completely transferred back into the organic phase. This procedure allowed for separation of the inhibitory factor from most of the pigments and other lipophilic substances present in the pine chloroplasts and yielded a preparation which could be subsequently fractionated by thin layer chromatography. UV absorption was found in two fast moving spots and at the origin. The fastest running spot from the thin layer chromatography plate was found to be the one containing most of the inhibitory activity.
Inhibitors of endogenous proteinases in Scots pine seeds: Fractionation and activity changes during germination
Authors: SALMIA M. AULIKKI 
Published: April 2006

AbstractResting seeds of Scots pine (Pinus sylvestris L.) contain inhibitors which inhibit the proteinase activity present in germinating seeds but have no effect on trypsin or chymotrypsin. When a crude inhibitor preparation was chromatographed on Sephadex G‐75, the inhibitor activity separated into four peaks with elution volumes corresponding to the molecular weights 24,000, 14,600, 14,000, and 9000. Each of the inhibitors affected both the hydrolysis of haemoglobin at pH 3.7 and the hydrolysis of casein at pH 5.4 and 7.0 by proteinase extracts prepared from “germinating” endosperms. These results suggest that one major proteinase was possibly acting in all the assays.In resting seeds inhibitor activity was present in both the embryo and the endosperm, the activity (per mg dry weight) in the embryo being about 2‐fold that in the endosperm. In the endosperms of germinating seeds the inhibitor activity per seed decreased at about the same rate as total N and dry weight. In the seedlings the activity per seedling remained approximately constant. The patterns of the activity changes suggest that the inhibitors do not control the breakdown of storage proteins; a more probable function is the protection of other cellular components from the high proteinase activities required for the rapid proteolysis during germination.
Turnover of cell wall polysaccharides of a Vinca rosea suspension culture
Authors: TAKEUCHI YUICHI , KOMAMINE ATSUSHI 
Published: April 2006

AbstractTurnover of cell wall components was examined in two growth phases of a batch suspension culture of Vinca rosea L. Three‐day‐cultured cells (cell division phase) and 5‐day‐cultured cells (cell expansion phase) were incubated with d‐[U‐14C]glucose. After various periods of incubation, extra‐cellular polysaccharides (ECP) and cell walls were isolated, and then the cell walls were fractionated to pectic substance, hemicellulose, and cellulose fractions. The results of the measurement of radioactivities and amounts of total carbohydrate in the ECP and cell wall fractions indicated that synthesis of pectic substance was more active in the cell division phase than in the cell expansion phase. From the results of the pulse‐chase experiments, in which cells prelabelled by incubation with d‐[U‐14C]glucose for 3 h were incubated in a medium containing unlabelled glucose for various periods, the gross degradation, net synthesis, and gross synthesis of cell wall components were estimated. Active degradation and synthesis were observed in the hemicellulose fraction, indicating that active turnover occurred in the hemicellulose fraction, while little degradation was found in the pectic substance and cellulose fractions.
Polyribosomes and protein synthesis in after‐ripening pear seeds
Authors: ALSCHER‐HERMAN RUTH , KHAN A. A. 
Published: April 2006

AbstractPolyribosomes have been isolated from pear seeds which show a capacity for in vitro protein synthesis. Translational capacity increased during stratification with a peak after 13 days of stratification. This increase was greatly diminished in seeds which were incubated at 25°C (“warm stratification”). The peak in protein synthetic activity coincides with the period of stratification required for normal development of excised embryos.
Fate of nitrate during initial nitrate utilization by nitrogen‐depleted dwarf bean
Authors: BRETELER HANS , CATE CHARLOTTE H. HÄNISCH TEN 
Published: April 2006

AbstractThe fate of nitrate and nitrogen‐15 was followed during the apparent induction phase (6h) for nitrate uptake by N‐depleted dwarf bean (Phaseolus vulgaris L. ev. Witte Krombek). Experiments were done with intact plants and with detached root systems. Qualitatively and quantitatively, xylem exudation from detached roots was a bad estimate of the export of NO−3 or NO−3‐15N from roots of intact plants. In vivo nitrate reductase activity (NRA) agreed well with in situ reduction, calculated as the difference between uptake and accumulation in whole plants, provided NRA was assayed with merely endogenous nitrate as substrate (‘actual’ NRA). The majority (75%) of the entering nitrate remained unmetabolized. Both nitrate reduction and nitrate accumulation occurred predominantly in the root system. Some (< 25%) of the root‐reduced nitrate‐N was translocated to the shoot. Nitrate uptake occurred against the concentration gradient between medium and root cells, and probably against the gradient of the electro‐chemical potential of nitrate. Part of the energy expended for NO−3 absorption came from the tops, since decapitation and ringing at the stem base restricted nitrate uptake.
Physiology of the tomato mutant alcobaca
Authors: KOPELIOVITCH E. , MIZRAHI Y. , RABINOWITCH H. D. , KEDAR N. 
Published: April 2006

Abstract Alcobaca is commonly regarded as an abnormally ripening mutant of the tomato (Lycopersicon esculentum Mill.). Alcobaca fruits were found to be similar to cv. Rutgers fruits in the following characteristics: time between full anthesis and the onset of ripening, response to ethephon, flavor, pH and concentrations of titratable acids, total soluble solids and reducing sugars. The pattern of CO2 and ethylene climacteric are similar in the two plant types, but the peak levels were lower and occurred later in alcobaca than in ‘Rutgers’. The mutant fruits differed from fruits of normal varieties in their greatly prolonged shelf life, their relatively low activity of polygalacturonase (PG) and polymethylgalacturonase (PMG), and their low level of endogenous ethylene. Fruits of the mutant harvested before the onset of ripening failed to reach normal pigmentation and remained yellow. Fruits harvested at the onset of ripening reached an orange color, while fruits ripened while attached to the plant reached almost normal pigmentation. These results suggest that alcobaca is a slow ripening mutant and does not belong to the category of non‐ripening mutants.
Biochemical studies on blossom end rot of tomatoes
Authors: DEKOCK P. C. , VAUGHAN D. , HALL A. , ORD B. G. 
Published: April 2006

AbstractThe causes of cell wall necrosis in Blossom End Rot (BER) of tomatoes have been investigated by comparing enzyme activities in healthy and affected tissues in the cultivars Grenadier and Moneymaker. Changes in the mineral contents of the tomatoes were in accordance with those of calcium deficient tissues. The phenolic contents of the affected tissues were increased as also were caffeic and chlorogenic acids. Phenolase and peroxidase activities were higher in affected fruits white catalase activities were higher in healthy fruits. 14C‐labelled leucine was incorporated into the proteins of the healthy fruits to the greatest extent but cell wall proteinbound hydroxyproline was greatest in affected fruits.
Radiation‐induced improvement of the freeze‐resistance of a cold‐sensitive wheat variety: Freeze‐tolerance and fatty acid patterns
Authors: TÓTH ECATERINA T. , VIGH LÁSZLÓ , KARVALY BÉLA , FARKAS TIBOR 
Published: April 2006

AbstractEffects of 3–15 krad 60Co gamma radiation on cereal seeds were investigated with regard to the frost hardiness of leaves of 5–7‐day‐old seedlings. Comparative studies were carried out on the gas‐chromatographically determined distribution patterns of fatty acids in different pools (total fatty acid, total lipid, polar lipids) of a cold‐resistant (cv. Mironowskaya 808) and a cold‐sensitive (cv. Penjamo 62) cultivar of wheat (Triticum aestivum L.). Parallelism between fatty acid distribution pattern, empirical parameters suggested for quantitative measures of cold tolerance (the ratio unsat/sat and double‐bond index), and the low‐temperature behaviour of shoots grown from radiation treated seeds of ‘Penjamo 62’, was also examined. To monitor differences in the fatty acid syntheses of ‘Mironowskaya 808’and ‘Penjamo 62’, and to demonstrate radiation‐induced changes in fatty acid turnover a [1–14C]‐acetate incorporation technique was employed.The results of practical importance are:1. A significant improvement in the frost‐resistance of the cold‐sensitive ‘Penjamo 62’variety could be achieved with 6–9 krad irradiation, the half‐freeze‐killing temperature dropping from −6 to about −18°C.2. Freeze‐hardiness, no matter whether inherited or gained, could be abolished by gamma irradiation with higher dose.The following conclusions of theoretical interest can be drawn:1. Low‐temperature behaviour of plant tissues is a dynamic property rather than a static one, not only the formation but also the breakdown of certain hydrocarbon chains may be of paramount relevance in cold‐tolerance.2. Not the linolenic (18:3) component, but rather the overall distribution pattern of the C18 family seems to correlate with low‐temperature‐responses of shoots.3. Empirical parameters investigated do not provide reliable quantitative measures of the susceptibility to freeze (and cold‐) injuries.4. Changes in the syntheses of some key proteins (e.g. peroxidase, water‐soluble proteins, etc.) may also be important in adaptation to low‐temperature conditions.
Photosynthetic activities of cadmium‐treated tomato plants
Authors: BASZYŃKI TADEUSZ , WAJDA LUCYNA , KRÓL MARIA , WOLIŃSKA DANUTA , KRUPA ZBIGNIEW , TUKENDORF ANNA 
Published: April 2006

AbstractTomato plants (Lycopersicum esculentum Mill. cv. Moneymaker) grown on nutrient medium containing cadmium exhibit reduced net photosynthesis and reduced contents of chlorophyll and accessory pigments. In chloroplasts isolated from cadmiumtreated plants photosystem II activity, as measured by 2,6‐dichlorophenolindophenol photoreduction, and photosystem II + I activity (H2O → methyl viologen) were both inhibited to about 60%. When 1,5‐diphenylcarbazide was used as artificial electron donor, no significant cadmium effect was observed. Photosystem I activity was not affected by cadmium. The fine structure of chloroplasts in cadmium‐treated plants was degenerated, similarly to senescence response. The principal symptom of cadmium action was the occurrence of large plastoglobules and a disorganization of the lamellar structure, mainly grana stacks. Transfer of cadmium‐treated plants into a medium with increased manganese level caused grana stacking and restoration of photosystem II activity.
Pattern of sulfate uptake during root elongation in maize: its correlation with productivity
Authors: CACCO G. , FERRARI G. , SACCOMANI M. 
Published: April 2006

AbstractThe efficiency of sulfate uptake was evaluated in excised roots of 22 maize genotypes, 12 inbreds and 10 hybrids, in order to study the relationship between the kinetic characteristics of the uptake and the grain productivity. During root elongation, the uptake capacity showed a pulse which appeared when the root reached 1/3 to 1/2 of its final length. The size of the accumulated pool of sulfate was significantly correlated with the productivity. The kinetic parameters of the uptake, Vmax and Km, followed the same trend, showing pulses, whoxe maximum had the same position for Vmax and Km in each genotype. The variability with the genotype of the size and duration of the Vmax pulse was not strictly connected with that of Km. The main correlation between Vmax and Km patterns was the following; inbreds were generally characterized by low Vmax and low Km; hybrids by high Vmax and high Km. As a consequence, in most cases, the benefit of the heterotic stimulation of Vmax was contrasted by the loss of affinity of the transport system or the nutrients.