bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cyanide‐Resistant Root Respiration and Tap Root Formation in Two Subspecies of Hypochaeris radicata
Authors: LAMBERS HANS , VAN DE DIJK SIEBREN J. 
Published: April 2006

AbstractRoot respiration of the tap root forming species Hypochaeris radicata L. was measured during tap root formation. A comparison was made of two subspecies: H. radicata L. ssp. radicata L., a subspecies from relatively rich soils, and H. radicata L. ssp. ericetorum Van Soest, a subspecies from poor acidic soils. Root respiration was high and to a large extent inhibited by hydroxamic acid (SHAM) before the start of the tap root formation, indicating a high activity of an alternative non‐phosphorylative electron transport chain. The rate of root respiration was much lower and less sensitive to SHAM when a considerable tap root was present. However, root respiration was also cyanide‐resistant when a tap root was present, indicating that the alternative pathway was still present. A decreased rate of root respiration coincided with an increase of the content of storage carbohydrates, mainly in the tap root. The level of reducing sugars was constant throughout the experimental period, and it was concluded that the activity of the alternative oxidative pathway was significant in oxidation of sugars that could not be utilized for purposes like energy production, the formation of intermediates for growth or for storage. Root respiration decreased after the formation of a tap root. This decrease could neither be attributed to a gradual disappearance of the alternative chain, nor to a decreased level of reducing sugars. No differences in respiratory metabolism between the two subspecies have been observed, suggesting that a high activity of the alternative oxidative pathway is not significant in adaptation of the present two subspecies to relatively nutrient‐rich or poor soils.
Fatty Acid Composition of Polar Lipids in Ceratodon purpureus and Pleurozium schreberi
Authors: KARUNEN PIRJO , ARO EVA‐MARI 
Published: April 2006

AbstractThe total amount of fatty acids in the mono‐ (MGDG) and diglycosyl diglyceride (DGDG) and more polar lipid fractions of frozen Ceratodon purpureus shoots was 4.6, 3.4 and 4.0 mg/g dry weight, respectively. The respective values for the tops of frozen Pleurozium schreberi were 2.6, 3.3 and 3.8 mg/g dry weight. The molar ratios MGDG/DGDG and MGDG + DGDG/chlorophyll were 1.3 and 3.7, respectively, for C. purpureus and 0.8 and 3.5 for P. schreberi.In C. purpureus the main fatty acids in the MGDG fraction were C 18:3ω3 (44% of the total fatty acids) and C 16:3ω3 (26%); in the DGDG fraction C 18:3ω3 (70%); and in the more polar lipid fraction C 18: 3ω3 (26%) and C 16:0 (25%). The proportion of C 20 polyunsaturated fatty acids was 15, 12 and 19% of the total fatty acids found in the MGDG, DGDG and more polar lipid fractions, respectively.In P. schreberi the proportion of C 20 polyunsaturated fatty acids was high in all polar lipid fractions (47, 42 and 25% in MGDG, DGDG and more polar lipid fractions, respectively). In addition, MGDG and DGDG fractions contained abundantly C 18:3ω3 (32 and 45%, respectively), and the more polar lipid fraction both C 18: 3ω3 (24%) and C 16:0 (27%).
Effect of Ammonium, Sucrose and Light on the Regulation of Nitrate Reductase Level in Pisum sativum
Authors: SIHAG R. K. , GUHA‐MUKHERJEE SIPRA , SOPORY SUDHIR K. 
Published: April 2006

AbstractIn shoot apices of 7‐day‐old dark‐grown peas the addition of ammonium along with the inducer nitrate resulted in a more than two‐fold increase in nitrate reductase activity. Individual amino acids, amides and amino‐acid mixture could not replace the ammonium effect. Ammonium also stimulated NADH‐glutamate dehydrogenase but not glucose‐6‐phosphate dehydrogenase. Sucrose caused a marked stimulation of nitrate reductase induction and showed synergistic effect with light. In presence of cordycepin and cycloheximide, induction of nitrate reductase was inhibited more if ammonium or sucrose was supplied along with the inducer. With actinomycin D, α‐amanitin or chloramphenicol, no differential inhibition took place in presence of ammonium. The inhibition of enzyme activity by chloramphenicol and 3‐(3,4‐dichlorophenyl)‐l,dimethyl urea was completely relieved by sucrose. Incorporation of 14C‐lysine was markedly stimulated by sucrose, but was not affected by ammonium. The effect of sucrose and light on 14C‐lysine incorporation was additive. Cordycepin and cycloheximide did not have any differential effect on 14C‐lysine incorporation in the presence of ammonium as well as sucrose. The inhibition of 14C‐lysine incorporation caused by chloramphenicol was relieved by sucrose. Sucrose also caused a marked increase in 3H‐uridine incorporation but ammonium had no effect. Actinomycin D and cordycepin blocked the sucrose dependent increase in 3H‐uridine incorporation.The results suggest that ammonium mediated stimulation may depend on a regulatory protein(s) synthesized in response to ammonium, whereas sucrose acts mainly by an overall increase in RNA and protein synthesis. The effect of light does not seem to be dependent on photosynthetic light reactions.
Stem Nodules in Aeschynomene indica and Their Capacity of Nitrogen Fixation
Authors: YATAZAWA MICHIHIKO , YOSHIDA SHIGEKATA 
Published: April 2006

AbstractThere has been no report on stem nodules with nitrogen fixing activity. Aeschynomene indica produce nodules on the aerial parts, and the stem nodules proved to be capable of considerable nitrogen fixation [C2H4 produced c. 4 μmol (g fresh weight)‐1 h‐1]. The stem nodules embed reddish tissues, and a rod‐shaped bacterium was isolated from the tissues. The bacterium was ascertained to form root and stem nodules on seedlings of A. indica.
Content of Adenosine Phosphate Compounds in a Long‐Day Duckweed, Lemna gibba G3, under Different Light and Nutritional Conditions
Authors: KONDO TAKAO , NAKASHIMA HIDEAKI 
Published: April 2006

AbstractThe levels of ATP ADP and AMP as well as the energy charge were examined in the long‐day duckweed. Lemna gibba G3, under different light and nutritional conditions. ATP and ADP content, but not AMP, decreased slightly when the plant was cultured with a medium depleted of sucrose or was exposed to continuous darkness. The energy charge was not affected either by changes in the light conditions or by the depletion of sucrose from the medium, although increase of fresh weight changed drastically under these conditions. The levels of ADP and AMP and the value of the energy charge remained nearly constant throughout a 1‐day period when the plant was exposed to short‐day, continuous light and continuous dark. ATP content decreased gradually during the light period of the short day and thereafter remained constant during the dark period. When the plant was exposed to continuous light. ATP content decreased until the 8th hour after beginning of the continuous light, only to recover rapidly to its original level during the phase coinciding with the preceding dark period of the short day. Under continuous dark conditions the ATP content remained constant throughout the day. It was concluded that the diurnal rhythm of physiological activities previously reported cannot be related to the energy charge.
Chlorophyllase and Photsystem
Authors: TERPSTRA WILLEMKE , GOEDHEER J. C. 
Published: April 2006

Abstract

Preliminary experiments showed that Triton X‐100 at low concentrations (appr. 0.01%) induces reversible changes in some photosynthetic reactions in Phaeodactylum cells without influencing their absorption spectrum; presumably membrane permeability is effects. Although DC PIP can pass through the cell membrane in the presence of 0.01% Triton X‐100, only a very low PS I activity, measured as MV photoreduction by DCPIP‐ascorbate, is observed with whole cells.
MV photoreduction sensitized by membrane fragments isolated from Phaetdactylum, Euglena, Porphyridium and Synechococcus after French Press treatment is much higher with Phaeodactylum than with the other organisms. Spinach shroma membrane fragments show higher photosensitizing activity than grana fragments.
MV photoreduction in the above mentioned experiments is not influenced by DCMU (2 × 10−6M) or sodium azide (0.01–0.05 M); KCN (4 × 10−3M) has an inhibiting effect only with the blue‐green alga Synechococcus. The reaction mechanism of chlorophyll‐sensitized MV photoreduction is discussed.
Chlorophyll in an aqueous medium containing Triton X‐100 (JsO.01%) sensitizes the photoreduction of MV by DCPIP ascorbate. A similar reaction is observed with chlorophyll combined with solubilized Phaeocdactylum chlorophyllase: in the latter case the presence of both MgCl2 and DTT is required.
MV‐photoreduction is concluded to be a very unreliable procedure for determining PS I activity in membranes if these membranes have been prepared in (the presence of detergents.
The results support the hypothesis that (prochlorophyllase is a PS I protein.
The capacity of PS I to reduce MV in vivo is discussed.
Association of Plastoquinone‐9 and Phylloquinone K1 with Photoconvertible Protochlorophyllide Holochrome
Authors: LICHTENTHALER H. K. , SUNDQVIST C. 
Published: April 2006

AbstractProtochlorophyllide holochrome was prepared from dark grown wheat seedlings in a saponin containing medium by precipitation with ammonium sulfale and differential centrifugaiion. During the different steps of purification the spectral properties and the photoconvertibility of prolochlorophyllide holochrome were measured concomitantly with its quinone and carotenoid content. Photoconvertible protochlorophyllide holochrome was enriched in quinones hut depleted of carolenoids compared with the whole etiolated leaf. The fractions containing long wavelength forms of photoconvcrtible protochlorophyllidc had a constant molar ratio of plastoquinonc. phylloquinone and protochlorophyllide of 1:1:2. The possibility of the prenylquinones to function as electron or hydrogen carriers between a hydrogen donor and protochlorophvliide is discussed.
Isolation and Mobilization of Storage Proteins from Apple Shoot Bark
Authors: O'KENNEDY BRENDAN T. , TITUS J. S. 
Published: April 2006

AbstractSeparation of the bark storage protein into three groups was achieved with minimal contamination from interfering cbromophores, using diethylaminoethyl cellulose column chromatography. Two of these groups were shown 10 contain neutral sugars in close association with the proteins. All three groups disappeared rapidly after the onset of growth. Polyacrylamide gel electrophoresis of the storage proteins showed the presence of eight prominent proteins. Ammo acid analysis of hydrolyzates of the proteins indicated that a large percentage of the protein nitrogen was in the form of basic amino acids.
Differentiation in Callus Cultures of Leaf of Two Species of Trigonella
Authors: SEN BASANTAK , GUPTA SUKUMAR 
Published: April 2006

AbstractCallusing of leaf segment of Trigonella corniculata L. and Trigonelta foenum graecum L. was observed on Murashige and Skoog's (MS) medium and White's (W) medium supplemented with naphthalene acetic acid (NAA; 0.5 mg/1) and coconut milk (15% v/v). Root, shoot and development of isolated leaf occurred in the calli of both the species on MS medium containing NAA amd coconut milk. Omission of coconut milk with subsequent addition of casein hydrolysale (CH) increased the number of differentiated organs per callus. In both the materials higher differentiation rate was observed at low irradiance than at high irradiance or in complete darkness. Initially the cells were diploid but at the 5th passage the calli became mixoploid wilh predominantly diploid cell populations. The differentiated organs were diploid.
Interactions of Divalent Cations in Their Action on ATPases from Cucumber Roots
Authors: KAWASAKI T. , KÄHR M. , KYLIN A. 
Published: April 2006

AbstractA microsomal fraction (10,000–30.000 g) was prepared from roots of Cucumis satirus L. (cv. Bestseller Fl) grown in solution culture. The ATPase activity was stimulated by Mg and Mn with optima between pH 6 and 7. Stimulation by Ca was obtained only above pH 7. Activations by Mg and Mn were inhibited by Ca, Mn and Mg interacted, so that Mn appeared strongly inhibitory for activation by Mg and Mg weakly inhibitory for activation by Mn: the simplest interpretation for this would be two separate enzymes. Cucumber accumulates and deposits Ca contrary to wheat and oat, which contain Ca‐activated ATPase in the pH region 6 to 7. The Ca data for cucumber are compared with earlier findings from wheat and oat and are tentatively related to known physiological differences.
The Effect of Abscisic Acid on the Uptake and Distribution of Ions in Intact Seedlings of Phaseolus vulgaris cv. Redland Pioneer
Authors: KARMOKER J. L. , VAN STEVENINCK R. F. M. 
Published: April 2006

AbstractAbscisic acid (ABA) was found to increase the accumulation of 36Cl, total Cl, 22Na and total Na+ in roots of intact bean seedlings. After an initial promotion. ABA inhibited longdistance transport of these ions from the root to the shoot. However, it consistently inhibited both uptake and transport of 42K and total K+ in intact bean seedlings. A promotion of net 36Cl influx (ψoc) and its accumulation in the root (Q*v) concomitant decrease in transport index (long‐distance transport as percentage of total influx) showed that ABA stimulates ‐36Cl transport at the tonoplast. It inhibited H4 extrusion and net 86Rb influx which agrees with a cation exchange theory K+/Rb+ transport.
Diurnal Fluctuations in the Activity of the Enzyme Nitrate Reductase in Lemna paucicostata
Authors: DEVI S. LAKSHMI , MAHESHWARI S. C. 
Published: April 2006

AbstractDiurnal fluctuations were observed in nitrate reducta.se activity in Lemna paucicostatu Hegelm, grown under 16‐h photoperiod. The enzyme activity showed a single peak in the middle of the photo period, i.e. 8 h after the onset of light. The activity decreased during the latter half of the photoperiod and reached a minimum level in the middle of the dark period. The peak in enzyme activity persists in continuous light as well as continuous dark, at least for a couple of days, suggesting the existence of endogenous rhythmicity
Effect of α‐Tocopherol, β‐Carotene, Monogalactosyldiglyceride and Phosphatidylcholine on Light‐Induced Degradation of Chlorophyll a in Acetone
Authors: VAN HASSELT PHILIP R. , DE KOK LUIT J. , KUIPER PIETER J. C. 
Published: April 2006

AbstractThe effect of α‐tocopherol, β‐carotene, monogalactosyldi‐glyceride and phosphatidylcholine on red light induced degradation of chlorophyll a was studied in acetone at 4°C. Monogalaclosyldi‐glyceride was ineffective up to a molar ratio of monogalactosyldi glyceride to chlorophyll of 1:10. α‐Tocopherol, β‐carotene and phosphatidylcholine inhibited chlorophyll degradation. Maximal protection by α tocopherol and β‐carotene was similar (76%) but on a molar basis a tocopherol was less effective. Protection by phosphatidylcholine was less than by a tocopherol and α‐carotene but the lipid was effective at a lower ratio of chlorophyll to protectant. Inhibition by phosphatidylcholine was independent of the degree of unsaturation of the fatty acids. Effects of β‐carotene and α‐tocopherol were additive at suboptimal concentrations, but addition did not increase the maximal protection of 76% by these substances alone. Phosphatidylcholine increased the effectiveness of α‐tocopherol and β‐carotene independent of their concentrations. It is suggested that interactions between lipids participate in the mechanism protecting chlorophyll a against photooxidation in the chloroplast membrane.
Analytical Procedures for the Sequential Extraction of 14C‐Labeled Constituents from Leaves, Bark and Wood of Cottonwood Plants
Authors: DICKSON RICHARD E. 
Published: April 2006

AbstractA procedure for the extraction, separation, and measurement of photosynthetically fixed 14C in up to 8 chemical fractions (CHCl), amino acids, organic acids, sugars, protein, starch, hemicellulose, and residue) from small samples (1 to 100 mg) of cottonwood (Populus deltoides Bartr.) leaf material is described. The different chemical fractions are extracted in a sequence of chemical, ion exchange, and enzymatic steps. The 14C‐activity in these major fractions is then determined with liquid scintillation spectrometry. These major fractions (e.g., sugars, amino acids, organic acids) can be further separated into their individual chemical components by standard thin‐layer or gas‐ chromatographic methods for quantitative analysis if specific activities are desired. The major advantage of the procedure is that many chemical fractions can be sequentially separated with good reproducibility from a small amount of plant material without transfer of the material from the original homogenizer or centrifuge tube.
Comparison of Plantago Species from Nutrient‐rich and Nutrient‐poor Conditions: Growth Response, ATPases and Lipids of the Roots, as Affected by the Level of Mineral Nutrition
Authors: KUIPER DAAN , KUIPER PIETER J. C. 
Published: April 2006

AbstractTwo groups of Plantago species, one of relatively nutrient‐rich habitats (Plantago major L., P. major L. ssp. pleiosperma Pilger and P. martrima L.) and the other of relatively nutrient poor habitats (P. lanceolata L., P. media L. and P. coronopus L.), were compared with respect to the response of the plants to alterations of the level of mineral nutrition. The comparison deals with growth response and root cell membrane functions (Ca2+ and Mg2+ stimulated ATPases and lipids). As far as these parameters are concerned species from relatively nutrientpoor habitats are not much affected by bringing the plants to high‐salt conditions, while the reverse was true for species from relatively nutrient‐rich habitats when transferred to low salt medium.
Action Spectra for in vivo and in vitro Conversions of Phycochrome b, a Reversibly Photochromic Pigment in a Blue‐Green Alga, and Its Separation from Other Pigments
Authors: BJÖRN G. S. 
Published: April 2006

AbstractPhycochrome b, one of the reversibly photochromic pigments found in Tolypothrix distorta seems to exist in only two forms: Pb500 and Pb570. The pigment has been spectroscopically demonstrated in vivo. It has also been separated from other pigments. Two different methods for separation have been used: isoelectric focusing and gel filtration. Preparations of purified phycobilisomes contain phycochrome b.The in vivo and in vitro absorption difference spectra were determined as well as action spectra for the conversions in vitro and in vivo of Pb500 to Pb570 and vice versa.Transformation kinetics of phycochrome b show that the conversions in both directions are initially first‐order reactions.
Micromanipulation of Cyanelles and a Cyanobacterium into Higher Plant Cells
Authors: BRADLEY P. M. 
Published: April 2006

AbstractA cyanobacterium (WPI‐I) and cyanelles of Glaucocystis nostochinearum Itz, have been introduced into epidermal cells of Allium cepa L. cv. Downing Yellow Globe bulb scales by microinjection. Uptake of cyanelles into protoplasts of Allium cepa and Daucus carota L. cv. Imperator 58 has also been induced with polyethylene glycol. Protoplasts were cultured until new cell walls were synthesized.
Dependence of the Post‐Illumination Burst of CO2 on Temperature, Light, CO2, and O2 Concentration in Wheat (Triticum aestivum)
Authors: DOEHLERT DOUGLAS C. , KU MAURICE S. B. , EDWARDS GERALD E. 
Published: April 2006

AbstractThe effect of environmental factors on the post‐illumination burst of CO2 (PIB) and O2 inhibition of apparent photosynthesis (APS) in wheat (Triticum aestivum L.) was studied in an open gas exchange system utilizing the mathematics of non‐steady‐state systems. Two components of inhibition by O2 are suggested: one is caused by photorespiration as measured from the maximum rate of the PIB, and the second is direct inhibition as taken as APS2%O2— (APSx%O2+ PIBx%O2) where X is the oxygen concentration.A primary PIB which occurred from 16–28 s after the darkening of the foliage was attributed to photorespiration. No primary PIB was observed at 2% O2. At a CO2 concentration of 100 μ/1 in the atmosphere (about 2.5 μM based on leaf intercellular concentration) and at 30°C and 145 nE/cm2 nE/cm2·s, APS decreased curve‐linearly with increasing O2 and reached an O2 compensation point of 560 μM (48% by volume), above which there was a net loss of CO2 in the light. The PIB increased with increasing O2 and became saturated at about 500 μM O2 but decreased above 900 μM O2. Direct inhibition of photosynthesis by O2 increased with increasing O2 concentration.Decreasing CO2 concentration had an effect on the magnitude of the PIB similar to that of increasing O2. At 30°C and 21% O2, the PIB increased with decreasing CO2 down to the CO2 compensation point (I) of 1.4 μM (47 μM/l). Below Γ, both PIB and CO2 evolution into the air in the light (at 21% O2) increased and then decreased at CO2 below 0.8 μM.The ratio of the PIB to APS2% o O2 increased linearly with increasing O2/CO2 ratio where O2 was held constant at 21% and CO2 was varied from 1.4 to 8.5 μM, while direct inhibition of photosynthesis expressed as a proportion of APS2%O2 remained constant over this range. At low CO2 concentration photorespiration as estimated by the PIB is the major part of O2 photosynthesis, while at atmospheric CO2 levels, direct inhibition is the major component.The PIB and APS at 2% and 21% O2 increased hyperbolically with increasing irradiance and all became light‐saturated at about 65 nE/cm2 s. The percentage total O2 inhibition of photosynthesis remained constant with increasing irradiance as did the relative contribution of direct O2 inhibition or photorespiration (PIB) to total O2 inhibition.The PIB and APS at 21% O2 had similar temperature optima of 30°C when experimental conditions were adjusted to provide a constant internal O2/CO2 solubility ratio at varying temperatures. However, with a constant external CO2 concentration, the temperature optimum for the PIB shifted upward to 35°C while that for APS at 21% O2 remained at 30°C, which may be due to an increased O2/CO2 concentration in the leaf with increasing temperature.
Relationships between Motor Cell Ultrastructure and Leaf Movements in Samanea saman
Authors: MORSE MARY JANE , SATTER RUTH L. 
Published: April 2006

AbstractWe examined the fine structure of motor cells in the secondary pulvinus of Samanea saman (Jacq.) Merrill, to aid in analyzing the cellular basis for K+ and Cl− driven, turgor regulated circadian leaflet movements. Pulvini that were (a) open (horizontal) in the light, (b) closed (vertical) in the dark, or (c) at an intermediate angle after 96‐h incubation in H2O in darkness, were cut into cross sections, sub‐divided into quadrants, and prepared for electron microscopy by standard methods.The walls of many cells are ridged, appearing scalloped in cross section, the plasmalemma following the wall contours. Plasmodesmata localized in pit fields are most numerous in the inner cortex of the extensor (abaxial), and least numerous in the outer cortex of the flexor (adaxial) (3.9 and 0.7, respectively, per μm2 wall area). Vacuole size, number of vacuoles per cell, and the condition of the electron dense precipitate within the vacuole also vary with cell location, multivacuolation being most pronounced in the outer cortex of the extensor. Chloroplasts are dimorphic: those in cells close to the vascular tissue are very large, circular in cross section, and contain huge starch deposits at all times, while those in the remainder of the cortex are smaller, usually oblong, and contain large starch deposits at the beginning of the dark period, but are devoid of starch at the beginning of the light period. However, both types of chloroplasts in excised pulvini incubated in H2O in darkness for 96 h still contain starch deposits, indicating that (1) light may promote starch degradation, or (2) starch degradation and resynthesis may be rhythmic.