bluuebunny/crossref_metadata_2025_split huggingface dataset:
K+ uptake in the early phases of germination of the photoblastic and thermosensitive seed of Phacelia tanacetifolia
Authors: PARDI D. , MORGUTTI S. , COCUCCI S. 
Published: April 2006

AbstractGermination of Phacelia tanacetifolia Benth. (cv. Bleu Clair) seeds is accompanied in its early phases by the development of the K+ uptake capacity. Dormancy due to light and high temperatures and the negative effect on seed germination of a medium with low water potential inhibit the development of potassium uptake. Fusicoccin, which promotes seed germination under all examined conditions, accelerates also the appearance of the K+ uptake capacity. The relationship between the development of K+ uptake and seed germination in Phacelia tanacetifolia is discussed.
The nitrate reductase stabilizing factor in cotton seeds
Authors: PURVIS ALBERT C. , TISCHLER CHARLES R. , FUNKHOUSER EDWARD A. 
Published: April 2006

AbstractA heat‐stable factor present in dry cotton (Gossypium hirsutum L.) seed, or in cotyledons until day 4 of germination, is capable of stabilizing labile nitrate reductase from other species. The stabilizing factor has no effect on stability of glyceralde‐hyde‐3‐phosphate dehydrogenase, but slightly improves the stability of glucose‐6‐phosphate dehydrogenase. Treatment with protease III, and to a lesser extent, trypsin, reduces the effectiveness of the stabilizer. The stabilizer is not a trypsin inhibitor. Dialysis demonstrates that the stabilizing factor has a molecular weight greater than 12,000 daltons. The factor precipitates between 25 and 75% (NH4) 2 SO4 saturation, and is effective at protein concentrations much lower than those required when casein is employed. – From the results of this study, we conclude that the factor which stabilizes labile nitrate reductase from cotton seed is proteinaceous.
Electrical resistance and ion movement through excised discs of sugar beet root tissue
Authors: AIKMAN D. P. , HARMER R. , RUST T. S. O. 
Published: April 2006

AbstractElectrical and tracer techniques were used to investigate the movement of Na+, K+ and Cl− through discs of a range of thicknesses cut from the root tissue of sugar beet, Beta vulgaris L. cv. Amono. At low external concentration the electrical resistance across a discs is less than that of an equivalent volume of solution. This does not appear to be due to a low resistance symplastic pathway but rather, to an enhanced concentration of cation in the apoplast. The resistance is proportional to the thickness of tissue. Although measurement of diffusion potential gives about 25 mV difference across the disc for a ten‐fold change in cation concentration, there is little discrimination between K+ and Na+.The observed tracer kinetics of 86Rb through the disc are consistent with those of diffusion, with a coefficient of diffusion, D, of 0.19 × 10−9 m2 s−1 and a tissue partition coefficient, k, of 0.27 (or of 2.7 if referred to the cell wall phase only). 36Cl gives a similar value for D, but has a k reduced by a factor of 3.3, a result that is consistent with the diffusion potential observation. However, a much larger discrimination would have been expected from the chemically measured cation exchange capacity.
Interactions of chlorophyll a and terpenoid alcohols with chloroplast acyl lipids in monomolecular films
Authors: LILJENBERG CONNY , SELSTAM EVA 
Published: April 2006

AbstractSurface pressure‐area measurements of purified chlorophyll a and monogalactosyl diacylglycerol in mixed monolayers were performed at 20°C with an automatic recording surface film balance at a constant compression rate. In addition structural parts of the chlorophyll and the monogalactosyl diacylglycerol as phytol and geranylgeraniol on one hand and different fatty acids on the other were studied pure and in mixed films. All components studied formed stable monomolecular films. Chlorophyll a and monogalactosyl diacylglycerol showed miscibility. Phytol was immiscible with synthetized monogalactosyl diacylglycerol containing only stearic acid. Mixed monolayers of phytol and monogalactosyl diacylglycerol isolated from barley containing 83 mol % a‐linolenic acid showed a strong interaction. An increased miscibility and association were found between phytol and fatty acids with increasing unsaturation. The results are discussed as a model for the localization of part of chlorophyll a in the thylakoid membrane.
Simple identification of the neutral chlorinated auxin in pea by thin layer chromatography
Authors: ENGVILD KJELD C. 
Published: April 2006

AbstractOne of the neutral chlorinated auxins of immature pea seeds was readily identified by thin layer procedures simple enough to serve in student's laboratory courses.4‐Chloroindole‐3‐acetic acid methyl ester was extracted from 50 g of commercial, frozen peas by either water or acetone, concentrated to small volumes and chromatographed in CHCl3 or CCl4 solvent systems separating the chlorinated auxin from indoleacetonitrile and the methyl or ethyl esters of indoleacetic acid.Colour reaction was carried out with some of the Salkowski FeCl3 sprays of which Ehmann's FeCl3/dimethylaminobenzaldehyde modification gave the most stable blue colour.
Changes in cold hardiness of introduced and native interior Alaskan evergreens in relation to water and lipid content during spring dehardening
Authors: KEDROWSKI RICHARD A. 
Published: April 2006

AbstractNeedle hardiness of introduced yellow pine, Pinus banksiana Lamb., lodgepole pine, P. contorta Dougl, and native white spruce, Picea glauca (Moench) Voss, were assessed by the effective prefreezing temperature method. Yellow pine needles were less hardy than lodgepole pine or white spruce needles in Alaska on each date measured. Although hardiness decreased in springtime in all species, decreases in hardiness in yellow pine began before temperatures were above −20°C, apparently in response to day length, while decreases in hardiness in lodgepole pine and white spruce began only when mean temperatures were above 0°C. Hardiness was increased by decreasing the water content of yellow pine and spruce needles. However, only the latter increased its field hardiness by decreased water contents, and only to a small degree. Large decreases in phospholipid occurred during the dehardening period, indicating the presence of major membrane‐associated changes. However, changes in hardiness did not closely parallel those in phospholipid; hardiness decreased before phospholipid did in spruce and after phospholipid did in lodgepole pine. In yellow pine, changes in hardiness were more closely related to changes in phospholipid content. Decreases in phospholipid appeared to be correlated with the day length in all species.
Seasonal abscisic acid accumulation in stem cambial region of Pinus silvestris, and its contribution to the hypothesis of a late‐wood control system in conifers
Authors: WODZICKI TOMASZ J. , WODZICKI ALINA B. 
Published: April 2006

AbstractGradual accumulation of natural inhibitor in tissues comprising the cambial zone and about 1 mm of the youngest phloem of the basal region of the Pinus silvestris stem during the season was detected by both extraction and diffusion methods followed by bioassays. The purified inhibitor was chromatographically identified as similar to abscisic acid. Taking into account earlier numerous results, the hypothesis is formulated that the seasonal accumulation of abscisic acid affects phenomena associated with auxin polar transport, so that autolytic breakdown of protoplasts, which terminates differentiation of tracheids in stem secondary xylem is delayed. This effect extends the maturation phase and results in formation of thick‐walled tracheids, characteristic for the late‐wood in conifers.
Leaf age and salinity influence water relations of pepper leaves
Authors: HOFFMAN G. J. , SHALHEVET J. , MEIRI A. 
Published: April 2006

AbstractPlant growth is reduced under saline conditions even when turgor in mature leaves is maintained by osmotic adjustment. The objective of this study was to determine if young leaves from salt‐affected plants were also osmotically adjusted. Pepper plants (Capsicum annuum L. cv. California Wonder) were grown in several levels of solution osmotic potential and various components of the plants' water relations were measured to determine if young, rapidly growing leaves could accumulate solutes rapidly enough to maintain turgor for normal cell enlargement.Psychrometric measurements indicated that osmotic adjustment is similar for both young and mature leaves although osmotic potential is slightly lower for young leaves. Total water potential is also lower for young leaves, particularly at dawn for the saline treatments. The result is reduced turgor under saline conditions at dawn for young but not mature leaves. This reduced turgor at dawn, and presumably low night value, is possibly a cause of reduced growth under saline conditions. No differences in leaf turgor occur at midday.Porometer measurements indicated that young leaves at a given salinity level have a higher stomatal conductance than mature leaves, regardless of the time of day. The result of stomatal closure is a linear reduction of transpiration.
Phycochromes b and d: their occurrence in some phycoerythrocyanin‐containing blue‐green algae (cyanobacteria)
Authors: BJÖRN G. S. 
Published: April 2006

AbstractPhycochromes b and d, two types of photoreversibly photochromic pigments previously extracted from the blue‐green alga Tolypothrix distorta, which contains phycoerythrocyanin, have now been found in three Anabaena strains also containing phycoerythrocyanin. Tests for the presence of phycochromes b and d in a number of blue‐green algae lacking phycoerythrocyanin have been negative. The possibility that phycochrome b‐type absorbance changes are due to changes in the α‐subunit of phycoerythrocyanin is discussed.
Nicotiana tabacum callus studies. X. ABA increases resistance to cold damage
Authors: BORNMAN CHRIS H. , JANSSON EVA 
Published: April 2006

AbstractThe effects of cis. trans abscisic acid on response to chilling was investigated in callused Nicotiana tabacum L. pith explants. Explants pretreated with 10‐4M ABA underwent approximately 50% less cellular leakage when chilled at 2°C under short‐day conditions for 10 d than the comparable non‐treated tissue. Growth in terms of fresh and dry weights, although poor in comparison to non‐chilled (20°C, long days) treatments, was more than twice that of the non‐ABA‐treated material. On an absolute dry weight basis proline content increased on chilling from 0.7 to 3.4 mg g‐1 in non‐ABA‐treated explants, but rose to nearly 17 mg g‐1 in the tissue treated with ABA. Only in the case of cold‐hardened. ABA‐treated tissue could some cells survive subzero temperatures and regenerate callus again. It is suggested that at least part of the ameliorating effects of ABA result from an increase in the level of proline.
Mesophyll cell properties for some C3 and C4 species with high photosynthetic rates
Authors: LONGSTRETH DAVID J. , HARTSOCK TERRY L. , NOBEL PARK S. 
Published: April 2006

AbstractLeaves of twelve C3 species and six C4 species were examined to understand better the relationship between mesophyll cell properties and the generally high photosynthetic rates of these plants. The CO2 diffusion conductance expressed per unit mesophyll cell surface area (gCO2cell) cell was determined using measurements of the net rate of CO2 uptake, water vapor conductance, and the ratio of mesophyll cell surface area to leaf surface area (Ames/A). Ames/A averaged 31 for the C3 species and 16 for the C4 species. For the C3 species gCO2cell ranged from 0.12 to 0.32 mm s‐1, and for the C4 species it ranged from 0.55 to 1.5 mm s‐1, exceeding a previously predicted maximum of 0.5 mm s‐1. Although the C3 species Cammissonia claviformis did not have the highest gCO2cell, the combination of the highest Ames and highest stomatal conductance resulted in this species having the greatest maximum rate of CO2 uptake in low oxygen, 93 μmol m‐2 s‐1 (147 mg dm‐2 h‐1). The high gCO2cell of the C4 species Amaranthus retroflexus (1.5 mm s‐1) was in part attributable to its thin cell wall (72 nm thick).
Extracellular invertase of Rhizobium japonicum and its role in free sugar metabolism in the developing root nodules of Sesbania grandiflora
Authors: SINGH RANGIL , SIDHU P. S. , VADHERA SHYAMA , SITAL J. S. , BHATIA I. S. 
Published: April 2006

AbstractExtracellular invertase of Rhizobium japonicum and its role in free sugar metabolism in the developing root nodules of Sesbania grandiflora L. was studied. The enzyme hydrolysed sucrose extracellularly, and its release was substrate inducible. 0.1 Mβ‐mercaptoethanol released the cell‐bound form of this enzyme. The production of invertase was low when glucose, galactose, mannose, fructose and raffinose were used as carbon sources in the growth medium. In the developing nodules sucrose was the major sugar. The content of fructose was low in comparison with that of glucose – suggesting that in the nodules, fructose is converted to glucose prior to its entry into the bacterial cell. The content of glucose synchronised with the pattern of change in the activity of invertase in the nodules.
Ethylene loss from the gas phase of container‐seal systems
Authors: NELSON NEIL D. , ISEBRANDS J. G. , RIETVELD WILLIS J. 
Published: April 2006

AbstractEthylene losses from the gas phase of various container‐seal systems were studied to develop acceptable methods for containing ethylene during experiments. Ethylene at an initial amount of 104 μI I‐1 was stored in glass vials at near atmospheric pressure for 20 h at 25–27°C and at 35% relative humidity external to the vials. Crimped serum vials sealed with saturated (NH4)2SO4 solution, neoprene rubber septa, nitrile rubber (Hycar) septa, butyl rubber septa, and brown translucent silicone rubber septa lost ethylene at the rate of 1.8, 10.2, 16.2, 16.5, and 40.2 nl m‐2s‐1, respectively, over the 20‐h period. Screw‐capped reaction vials sealed with white silicone rubber septa lost ethylene at the rate of 30.2 nl m‐2s‐1. The (NH4)2SO4 solution was utilized as a seal by inverting a vial so that the salt solution covered the internal surface of the vial septum. Saturated (NH4)2SO4 solution is an effective seal. Silicone rubber should be avoided as a seal in systems for containing ethylene. Ethylene production values in the literature may be underestimates where silicone rubber seals have been used.
Évolution horaire au cours d'une journée normale de la photosynthèse, de la transpiration, de la respiration foliaire et racinaire et de la nutrition N.P.K. chez Zea mays
Authors: MASSIMINO DANIEL , ANDRÉ MARCEL , RICHAUD CHRISTIANE , DAGUENET ALAIN , MASSIMINO JACQUELINE , VIVOLI JEAN 
Published: April 2006

Abstract Hourly development during a normal day of photosynthesis, transpiration, leaf and root respiration, and of N.P.K nutrition in Zea mays.Metabolism of Zea mays L. cv. INRA F7×F2 can be measured hourly with the “C23A system”, under favourable and constant growth conditions. The photosynthesis is especially stable and is submitted only to a development linked with the leaf surface growth. During the vegetative stage the leaf surface increases regularly both in the day and in the night. The water loss does not change during the diurnal period and remains important during the night if humidity is less than 100%. The leaf respiration is nearly stable. The root respiration, measured with O2 and CO2, fluctuates according to a typical rhythm with two maxima. Day and night mean rates were about the same. The respiratory quotient is about one during the vegetative stage. There is no decrease in the rate of phosphate absorption during the night, and a very small decrease in the rate of nitrate absorption. Ammonium is totally consumed in the first hours after renewal of the nutrient solution. At the same time the potassium consumption is decreased, and then presents a maximum followed by a night reduction. Under our conditions, all of the observations allowed us to assume the presence of an adequate reserve of assimilates and suggest the existence of a precise regulation process, which can ensure an even day night functioning of the plant metabolism, but which does not preclude the presence of internal rhythms, as indicated by the oscillation of the root respiration.
Low temperature, gibberellin and acid lipase activity in removal of apple seed dormancy
Authors: ŻARSKA‐MACIEJEWSKA BOŻENA , SIŃSKA IRENA , WITKOWSKA EWA , LEWAK STANISŁAW 
Published: April 2006

AbstractThe activity of acid lipase and the level of gibberellin A4 (GA4) were determined in apple embryos excised from seeds after different time periods of stratification and subsequently cultured in darkness at 4°C or at 25°C. Enzyme activity and GA4 content were higher at 4°C. Exogenous gibberellin stimulated lipase activity, while AMO‐1618, an inhibitor of gibberellin biosynthesis, inhibited, to the same degree, both the enzyme activity and the GA4 accumulation. The involvement of GA4 and lipolytic enzymes in cold‐mediated removal of embryonal dormancy has been discussed and compared with the role of these two factors in light‐stimulated germination of dormant apple embryos, described earlier (Smoleńska and Lewak 1974).
Turnover of cell wall polysaccharides of a Vinca rosea suspension culture
Authors: TAKEUCHI YUICHI , KOMAMINE ATSUSHI , SAITO TOMOO , WATANABE KAZUO , MORIKAWA NAOTAKE 
Published: April 2006

AbstractThree‐day‐cultured cells of Vinca rosea L. (in the cell division phase) and 5‐day‐cultured cells (in the cell expansion phase) prelabelled with d‐[U‐14C] glucose were incubated in a medium containing unlabelled glucose. After various periods of chase, extra‐cellular polysaccharides (ECP) and cell walls were isolated, and cell walls were fractionated into pectic substances, hemicellulose, and cellulose fractions. After acid hydrolysis, the radioactive constituents in the pectic substances and hemicellulose fractions were analyzed. Active turnover was observed in arabinose and galactose in the hemicellulose fraction of cell walls, while the constituents of the pectic substances, and xylose and glucose in the hemicellulose fraction did not undergo active turnover. The proportion of radioactivities of arabinose and galactose in total radioactivity of ECP increased markedly after chasing. These results indicate that arabinogalactan was synthesized, deposited in the cell wall, degraded rapidly, and made soluble in the medium as a part of ECP.
Occurrence of steryl and wax esters in Dicranum elongatum
Authors: KARUNEN PIRJO , MIKOLA HEIKKI , EKMAN RAINER 
Published: April 2006

AbstractThe steryl and wax esters of the frozen subarctic moss Dicranum elongatum Schleich contained fatty acids 39.8 mg per gram dry green tissue. The content decreased with increasing age of the moss shoots, but no great changes were found in the fatty acid pattern of the esters. The major part of the steryl and wax ester fraction of the green shoots was made up of esterified sterols (85%), and the rest (15%) of esterified aliphatic alcohols. No great changes were found in their relative proportions with increased age of the shoots. Some changes were evident in the pattern of individual esterified sterols, however. The proportion of cycloartenol was lower in the older parts than in the green part, and the proportion of campesterol, stigmasterol, and β‐sitosterol were lower in the green part. The major esterified aliphatic alcohols were 1‐octadecanol, phytol and geranylgeraniol. The proportion of geranylgeraniol was highest in the green part and that of phytol in the older parts. The main alcohol of the surface lipids was 1‐octadecanol.
Induction of DNA synthesis by 2,4‐dichlorophenoxyacetic acid during callus induction in Jerusalem artichoke tuber tissues
Authors: YAJIMA YASUO , YASUDA TAKESHI , YAMADA YASUYUKI 
Published: April 2006

AbstractDuring the induction of DNA synthesis in Jerusalem artichoke (Helianthus tuberosus L.) tuber by 2,4‐D, the 2‐14C‐2, 4‐D from the agar medium rapidly incorporated into the ethanol soluble and insoluble fractions. Although the 2,4‐D level in the ethanol soluble fraction decreased on transplantation of the tissue from the 2‐14C‐2,4‐D medium to medium without the auxin, its level in the buffer‐soluble and ‐insoluble macromolecular fractions increased. The purified, buffer‐insoluble macromolecules were chromatin. The 2,4‐D binding to chromatin particularly increased during DNA synthesis. The histone contents of chromatin decreased as DNA synthesis progressed. The polyacrylamide gel electrophoretic patterns of the histones showed a decrease in the moderately lysine‐rich histone fraction as compared to other fractions. Thus, the decrease in the histone level caused by 2,4‐D and the presence of the 2,4‐D moderately lysine‐rich histone complex may be closely related to the induction of DNA synthesis by 2,4‐D in cells.
The effects of irradiance on growth, respiration and nitrate reductase activity of Terminalia ivorensis and Terminalia superba
Authors: FASEHUN F. E. 
Published: April 2006

AbstractControlled‐environment experiments were conducted to determine the effect of three irradiance levels obtained by artificial shading (40%, 65% and 100% light) on the growth, distribution of photosynthate, relative growth rate, net assimilation rate, respiration and nitrate reductase activities in the leaves of seedlings of Terminalia ivorensis and Terminalis superba, two important tropical tree species.Total dry weights of both species increased with increasing irradiance level during growth. Shading affected the percentage dry matter in the roots and number of leaves of both species. Relative growth rate, net assimilation rate, respiration and nitrate reductase in the leaves of both species increased with increases in irradiance level during growth. Significant differences between the species were observed in most of the parameters studied.
Effect of SO32‐ on the activity of ribulose bisphosphate carboxylase from seedlings of Pinus silvestris
Authors: GEZEILUS KERSTIN , HALLGREN JAN‐ERIK 
Published: April 2006

Abstract The effect of sulphite on ribulose bisphosphate carboxylase, extracted from needles of Pinus silvestris L., was studied in vitro at pH 8.15 and 25°C. 1 mM and higher concentrations of SO32‐ inhibited the enzyme.The enzyme was activated either in the assay medium (2.5 – 20 mM HCO3, 20 mM MgCl2) or in 10 or 20 mM HCO3‐ and 20–25 mM MgCl2. Linear reciprocal plots of the activity versus the substrate concentration were obtained, when the HCO3‐ concentration during activation was 4 mM or higher. When the enzyme was activated at high HCO3‐ and Mg2+ concentrations, the Km(CO2) was c. 27 μM. With respect to HCO3‐. SO32‐ inhibited the enzyme in a non‐competitive fashion. The inhibition was similar, whether SO32‐ was present during activation or not. Apparently. SO32‐ did not interfere with the binding of CO2 and Mg2+ at the activating site. The K1 was 11–13 mM SO32‐. With respect to ribulose bisphosphate the inhibition was also noncompetitive.Similar results with respect to HCO3‐ were obtained for spinach, Spinacia oleracea L., which is contrary to earlier reports.