| inhibition of elongation growth by two sesquiterpene lactones isolated from helianthus annuus l. : possible molecular mechanism. | two sesquiterpene lactones belonging to the germacranolides were isolated from the leaves and stems of helianthus annuus l. their formation in the plant is light-dependent. both sesquiterpene lactones (sl) strongly inhibit indole-3-acetic acid (iaa)-induced elongation growth of avena sativa l. coleoptile segments and helianthus annuus l. hypocotyl segments. both sl do not, however, inhibit acid-induced growth nor growth triggered by fusicoccin at all. in the presence of dithiothreitol (dtt), the ... | 1982 | 24272656 |
| incorporation of [4-(14)c] cholesterol into steryl derivatives and saponins of oat (avena sativa l.) plants. | sterols from both green and etiolated oat plants (avena sativa) contain sitosterol, stigmasterol, cholesterol, δ(7)-stigmastenol, δ(7)-cholestenol and campesterol. in the saponin fraction avenacosides a and b and 26-desgluco-avenacosides a and b were detected. etiolated plants incorporated [4-(14)c] cholesterol into steryl derivatives (esters, glycosides and acylated glycosides) and also into all of the 4 saponins. [4-(14)c] sitosterol, however, is incorporated only into steryl derivatives, but ... | 1982 | 24257768 |
| synthesis of oat globulin precursors : analogy to legume 11s storage protein synthesisa. | the oat (avena sativa l.) seed globulin was found to be synthesized in vitro as 60,000 to 64,000 dalton precursors. in vivo protein labeling yielded polypeptides of 58,000 to 62,000 daltons, suggesting cleavage of signal sequences from the precursors. further cleavage is apparently required to separate the alpha and beta polypeptide sequences which are known to form disulfide-linked 53,000 to 58,000 dalton species in the (alphabeta)(6) holoprotein. the data are discussed with respect to analogou ... | 1982 | 16662760 |
| effects of exogenous 1,3-diaminopropane and spermidine on senescence of oat leaves : ii. inhibition of ethylene biosynthesis and possible mode of action. | the effects of the polyamines spermidine and 1,3-diaminopropane on ethylene biosynthesis and chlorophyll (chl) loss were studied in peeled leaves of oat (avena sativa l., var. victory) incubated in the dark. peeling off the epidermal cells induces an increase in 1-aminocyclopropane-1-carboxylate (acc) synthase activity, resulting in an enhanced acc and ethylene formation. both polyamines inhibit ethylene biosynthesis from methionine by inhibiting acc synthase activity and, more effectively, the ... | 1982 | 16662726 |
| effects of exogenous 1,3-diaminopropane and spermidine on senescence of oat leaves : i. inhibition of protease activity, ethylene production, and chlorophyll loss as related to polyamine content. | excision and dark incubation of oat (avena sativa l., var. victory) leaves cause a sharp increase in protease activity, which precedes chl loss. both these senescence processes are inhibited by exogenously applied 1,3-diaminopropane (dap), which occurs naturally in leaf segments. the inhibition of protease activity is much greater in vivo than in vitro, suggesting inhibition of protease synthesis as well as protease action by dap. chl breakdown in leaves of radish and broccoli, which also senesc ... | 1982 | 16662725 |
| proteolysis alters the spectral properties of 124 kdalton phytochrome from avena. | native phytochrome from avena sativa l. is homogeneous with a monomeric molecular weight of 124 kdalton; 6-10 kdalton larger than the heterogeneous "120" kdalton preparations previously considered to be undegraded (vierstra and quail, 1982, proc. natl. acad. sci. usa, 79: 5272-5276). the phototransformation difference spectrum (pr-pfr) of 124 kdalton phytochrome measured in crude extracts has a minimum in the farred region at 730 nm, the same as that observed in vivo. these spectral properties c ... | 1982 | 24272311 |
| correlation between the lipid composition and the responsiveness of avena sativa stem segments to gibberellic acid. | the lipid composition of avena sativa stem segments was manipulated using basf 13-338 (formerly sandoz 9785) and growth temperature, in order to establish whether there were correlations between responsiveness of the tissue to gibberellic acid (ga(3)) and the presence, before hormone treatment, of specific lipid components. high correlations were obtained between ga(3)-induced growth and total phospholipid, individual phospholipids, and fatty acids (except for linolenic acid), total saturated fa ... | 1982 | 16662703 |
| plasma membranes from oats prepared by partition in an aqueous polymer two-phase system : on the use of light-induced cytochrome b reduction as a marker for the plasma membrane. | presumptive plasma membrane fractions have been prepared from oat (avena sativa l. cv. brighton) roots and shoots, respectively, by partition of microsomal fractions in a dextran-polyethylene glycol two-phase system. the plasma membranes had a high affinity for the polyethylene glycol-rich upper phase, whereas membranes from mitochondria and other organelles partitioned in the dextran-rich lower phase or at the interface. thus, relatively pure plasma membranes were obtained by only two partition ... | 1982 | 16662693 |
| effect of vanadate, molybdate, and azide on membrane-associated atpase and soluble phosphatase activities of corn roots. | the effects of vanadate, molybdate, and azide on atp phosphohydrolase (atpase) and acid phosphatase activities of plasma membrane, mitochondrial, and soluble supernatant fractions from corn (zea mays l. wf9 x mo17) roots were investigated. azide (0.1-10 millimolar) was a selective inhibitor of ph 9.0-atpase activity of the mitochondrial fraction, while molybdate (0.01-1.0 millimolar) was a relatively selective inhibitor of acid phosphatase activity in the supernatant fraction. the ph 6.4-atpase ... | 1982 | 16662676 |
| localization of phytochrome in oats by electron microscopy. | phytochrome was localized by immunoelectron microscopy in cells of the coleoptile tip of etiolated and irradiated oat (avena sativa l., cv. konata) seedlings. by using ultrathin frozen sections and immunopurified, monospecific antibodies, both the sensitivity and resolution of the immunocytochemical assay were increased. the results with etiolated plants agree with and extend previously published data. a brief red light illumination caused the redistribution of phytochrome from a diffuse to a mo ... | 1982 | 16662762 |
| light-induced h secretion and the relation to senescence of oat leaves. | when abraded oat (avena sativa l. cv victory) leaf segments are floated on kcl solution, white light causes acidification of the solution external to leaf tissue. the presence of mannitol amplifies the light-induced proton secretion. mature leaves as well as young ones acidify the medium in light, while senescing leaves (after 3 to 4 days incubated in water in the dark) lose the ability to produce this response to light. the decrease in h(+) secretion is already measureable after as little as 30 ... | 1982 | 16662624 |
| pigment-protein complexes of illuminated etiolated leaves. | photoconversion of protochlorophyllide in etiolated leaves of avena sativa l., var. pennal or peniarth and phaseolus vulgare l., var. ;the prince' results in the sequential appearance of spectrally distinct chlorophyllide complexes (chlide 678, 684, and 672). this paper reports on the generation of similar forms in vitro, under controlled conditions, using well characterized etioplast membranes enriched in the enzyme protochlorophyllide reductase. excess nadp(+) and nadph stabilize complexes rel ... | 1982 | 16662606 |
| comparative phytochrome immunochemistry as assayed by antisera against both monocotyledonous and dicotyledonous phytochrome. | preparation and characterization of antisera against lettuce (lactuca sativa l., cv. grand rapids) and pea (pisum sativum l., cv. alaska) phytochrome is described. these antisera, together with previously obtained antisera against zucchini (cucurbita pepo l., cv. black beauty) and oat (avena sativa l., cv. garry) phytochrome, were used to compare by ouchterlony double immunodiffusion phytochrome isolated from etiolated lettuce, pea, bean (phaseolus vulgaris l., cv. taylor horticultural bush), zu ... | 1982 | 16662599 |
| evidence from studies with acifluorfen for participation of a flavin-cytochrome complex in blue light photoreception for phototropism of oat coleoptiles. | the diphenyl ether acifluorfen enhances the blue light-induced absorbance change in triton x100-solubilized crude membrane preparations from etiolated oat (avena sativa l. cv. lodi) coleoptiles. enhancement of the spectral change is correlated with a change in rate of dark reoxidation of a b-type cytochrome. similar, although smaller, enhancement was obtained with oxyfluorfen, nitrofen, and bifenox. light-minus-dark difference spectra in the presence and absence of acifluorfen, and the dithionit ... | 1982 | 16662593 |
| localization of phytochrome in oats by electron microscopy. | phytochrome was localized by immunoelectron microscopy in cells of the coleoptile tip of etiolated and irradiated oat (avena sativa l., cv. konata) seedlings. by using ultrathin frozen sections and immunopurified, monospecific antibodies, both the sensitivity and resolution of the immunocytochemical assay were increased. the results with etiolated plants agree with and extend previously published data. a brief red light illumination caused the redistribution of phytochrome from a diffuse to a mo ... | 1982 | 16662591 |
| does ethylene play a role in the release of lateral buds (tillers) from apical dominance in oats? | the growth of lateral buds (tillers), which are undergoing release from apical dominance, was measured in upright and gravistimulated intact avena sativa l. cv. ;victory' (oat) shoots as well as in isolated avena stem segments treated with kinetin and sucrose. during release, the tiller bud initially shows a slow rate of elongation accompanied by swelling. it is followed by a more rapid rate of elongation. ethylene (c(2)h(4)) production in shoot segments containing a tiller bud was found to occu ... | 1982 | 16662580 |
| ethylene as an effector of wound-induced resistance to cellulase in oat leaves. | peeling the abaxial epidermis from oat leaves (avena sativa var. victory) induces the formation of wound ethylene and the development of resistance to cellulolytic digestion of mesophyll cell walls. ethylene release begins between 1 and 2 hours after peeling in the light or dark. aminoethoxyvinylglycine (avg, 0.1 millimolar), cocl(2) (1.0 millimolar), propyl gallate (pg, 1.0 millimolar) or aminooxyacetic acid (aoa, 1.0 millimolar) inhibits, whereas agno(3) stimulates wound ethylene formation. in ... | 1982 | 16662576 |
| wound-induced resistance to cellulase in oat leaves. | peeling the epidermis induces the development of resistance to cellulolytic digestion in the mesophyll cell wals of the first leaf of 1- to 3-week-old oat seedlings (avena sativa var. victory). development of resistance occurs between 3 and 11 hours after the abaxial epidermis is peeled from the blade, and is inhibited by actinomycin d (20 micrograms per milliliter) or cycloheximide (1 microgram per milliliter). other methods of wounding (cutting with a razor blade, stabbing with a dissection ne ... | 1982 | 16662575 |
| interaction of nitroxide spin labels with chloroplasts. | chloroplasts isolated from oats eliminated the electron spin resonance (esr) signals from spin labels in white light and partially restored them in far-red light. only the white light-mediated reaction was blocked by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (dcmu). in contrast, oat (avena sativa l. cv. garry and park) leaf mesophyll protoplasts oxidized the spin labels in both white and far-red light, with and without dcmu. light had no obvious effect on spin label motion within chloroplast membr ... | 1982 | 16662554 |
| localization of spin labels in oat leaf protoplasts. | an assay based on light-mediated oxidation was used to determine whether specific spin labels were partitioned throughout the protoplast or retained in the plasmalemma of avena sativa l. cv. garry and park. many classes of spin label were tested, including phospholipids, fatty acid, fatty acid methyl ester, maleimide, iodoacetamide, short chain hydrocarbon, androstane, 2,2,6,6-tetramethyl-4-aminopiperidinooxyl (tempamine) and 2,2,6,6-tetramethylpiperidinooxyl (tempo). all except the phosphotidyl ... | 1982 | 16662553 |
| cell-free synthesis of phytochrome apoprotein. | a single polypeptide is immunospecifically precipitated by monospecific antiphytochrome from the total translation products of both wheat-germ and rabbit-reticulocyte cell-free protein synthesizing systems programmed with oat (avena sativa l.) poly(a) rna. the mobility of this polypeptide is slightly lower on sodium dodecyl sulfate (sds) polyacrylamide gel electrophoresis than that of immunoaffinity-purified, 118 kdalton phytochrome and corresponds to an apparent molecular weight of 124 kdalton. ... | 1982 | 24271769 |
| the influence of gibberellic acid and temperature on the growth rate of avena sativa stem segments. | a micro-growth measuring technique was used to determine the growth response of stem segments of avena sativa cv. avon to a variety of gibberellic acid (ga(3)) concentrations over a range of incubation temperatures. growth rate varied with ga(3) concentration, the temperature at which the rate was measured, and the growth temperature of the plants prior to excision of the segments. the curves relating segment extension rates to temperature were affected by ga(3) such that the linear portion of t ... | 1982 | 16662529 |
| biological properties of d-amino acid conjugates of 2,4-d. | some d-amino acid (glutamic acid, valine, or leucine) conjugates of 2,4-dichlorophenoxyacetic acid (2,4-d) at 10(-5) molar, stimulated elongation of avena sativa l. var mariner coleoptile sections and growth of soybean (glycine max. l. var amsoy) tissue as much as did the l-amino acid conjugates at 10(-6) molar. the d-methionine conjugate did not stimulate growth of soybean root callus tissue but did stimulate avena elongation. the d-aspartic acid conjugate did not stimulate elongation of avena ... | 1982 | 16662495 |
| the hydraulic conductivity as a criterion for the membrane integrity of protoplasts fused by an electric field pulse. | the hydraulic conductivity of the membrane, lp, of fused plant protoplasts was measured and compared to that for unfused cells, in order to identify possible changes in membrane properties resulting from the fusion process. fusion was achieved by an electric field pulse which induced breakdown in the membranes of protoplasts in close contact. close membrane contact was established by dielectrophoresis. in some experiments pronase was added during field application; pronase stabilizes protoplasts ... | 1982 | 24271667 |
| phytochrome-controlled extension growth of avena sativa l. seedlings : ii. fluence rate response relationships and action spectra of mesocotyl and coleoptile responses. | fluence rate response curves for light-induced inhibition of mesocotyl growth and promotion of coleoptile growth in etiolated avena sativa l. (cv. victory) were developed. the irradiation time was 24 h. fluence rates between 10(-6) and 10(5) nmol m(-2)s(-1) and 30 wavelengths between 563 and 1,093 nm were used. the main conclusions are as follows: 1. both organs exhibit a low fluence rate response as well as a high fluence rate response. 2. the mesocotyl response is more sensitive to light than ... | 1982 | 24276066 |
| phytochrome-controlled extension growth of avena sativa l. seedlings : i. kinetic characterization of mesocotyl, coleoptile, and leaf responses. | the effects of continuous red and far-red light and of brief light pulses on the growth kinetics of the mesocotyl, coleoptile, and primary leaf of intact oat (avena sativa l.) seedlings were investigated. mesocotyl lengthening is strongly inhibited, even by very small amounts of pfr, the far-red light absorbing form of phytochrome (e.g., by [pfr]≈0.1% of total phytochrome, established by a 756-nm light pulse). coleoptile growth is at first promoted by pfr, but apparently inhibited later. this in ... | 1982 | 24276065 |
| regulation of h excretion : role of protein released by osmotic shock. | when the protoplasts of peeled oat leaf segments (avena sativa l.) expand after a brief plasmolysis (osmotic shock), fusicoccin-enhanced h(+) excretion is reduced and protein is released to the rehydration medium. this shock protein seems to arise from the cell surface, not from the interior of leaky cells or from broken cells, because (a) the protein differs quantitatively and qualitatively from protein of cell homogenates as determined by sodium dodecyl sulfate-polyacrylamide gel electrophores ... | 1982 | 16662324 |
| regulation of h excretion : effects of osmotic shock. | osmotic shock, a 15-minute plasmolysis followed by a 15-minute rehydration in the cold, is a nondestructive technique which inhibits fusicoccin-stimulated h(+) excretion from oat mesophyll cells (avena sativa l.). osmotic shock also causes a loss of intracellular solutes and stimulates h(+) uptake, but osmoregulation can still occur, and enhanced h(+) uptake is observed only at low external ph. it is concluded that osmotic shock interferes directly with the excretion of h(+) rather than affectin ... | 1982 | 16662323 |
| evidence for a cl-stimulated mgatpase proton pump in oat root membranes. | the possibility that plant membrane-bound mgatpases may act as electrogenic proton pumps has been investigated. using an oat (avena sativa l. cv. victory) root membrane preparation which is partially enriched in tightly sealed vesicles, we have shown that mgatp stimulates the uptake of the membrane-permeable anion [(14)c]scn(-) by the vesicles; this indicates that an electrical potential (interior positive) is generated across the membrane. both cl(-) ions and the proton ionophore trifluorometho ... | 1982 | 16662299 |
| energy coupling in h-amino acid cotransport : atp dependence of the spontaneous electrical repolarization of the cell membranes in oat coleoptiles. | experiments were undertaken in order to test the mechanism of energy coupling for amino acid uptake proposed in the cotransport hypothesis. according to the hypothesis an electrochemical potential difference in h(+) is established by active h(+) extrusion. that potential difference then drives the cotransport of h(+) and amino acids into the cells. application of amino acids to oat (avena sativa var. victory) coleoptiles induced transient depolarizations of the cell membrane electrical potential ... | 1982 | 16662266 |
| adenylate levels, energy charge, and phosphorylation potential during dark-light and light-dark transition in chloroplasts, mitochondria, and cytosol of mesophyll protoplasts from avena sativa l. | the compartmentation of cellular energy relations during dark-light and light-dark transitions was studied by means of a newly developed technique to fractionate oat (avena sativa l., var. arnold) mesophyll protoplasts. using an improved microgradient system with hydrophobic and hydrophilic layers of increasing density, a pure plastid pellet (up to 90% of total chloroplasts) could be separated from an interphase of only slightly contaminated mitochondria (70 to 80% of total mitochondria), and a ... | 1982 | 16662227 |
| relation of polyamine synthesis and titer to aging and senescence in oat leaves. | polyamine biosynthesis in senescing leaves of avena sativa l. was measured by determining the activities of arginine decarboxylase (ec 4.1.1.19), ornithine decarboxylase (ec 4.1.1.17) and s-adenosyl-l-methionine decarboxylase (ec 4.1.1.50). polyamine content was also estimated by thin layer chromatography and high performance liquid chromatography. arginine decarboxylase activity decreases progressively in aging attached first leaves and in senescing excised leaves in the dark. conversely, it in ... | 1982 | 16662218 |
| sources of ammonium in oat leaves treated with tabtoxin or methionine sulfoximine. | excised 7-day-old oat (avena sativa l. cv. jaycee) leaves were incubated in media containing 7.1 millimolar kno(3) and 0.15 millimolar tabtoxin or 1 millimolar methionine sulfoximine (mso) to investigate the sources of the observed ammonium accumulated. tabtoxin and mso are known inhibitors of glutamine synthetase, the first enzyme in the primary pathway of ammonium assimilation. during a 4- to 6-hour incubation, there was little net change in protein or total amino acid concentration. alanine, ... | 1982 | 16662206 |
| osmoregulation in the avena coleoptile : control of solute uptake in peeled sections. | peeled avena sativa coleoptile sections (i.e. sections from which the epidermis has been removed) have been used to study the control of solute uptake under conditions where the uptake is not limited by the cuticular barrier. in the presence of 2% sucrose, auxin enhances the rate at which the total osmotic solutes increase, but this appears to be a response to the increased growth rate, inasmuch as the auxin effect is eliminated when growth is inhibited osmotically. when sections are incubated i ... | 1982 | 16662195 |
| pyruvate orthophosphate dikinase from the immature grains of cereal grasses. | pyruvate orthophosphate dikinase has been identified in the green grains of eight cereal grasses, most of which are classified as c(3) plants. the wheat (triticum aestivum l. cv. lerma rojo) grain enzyme was further investigated: activity was low in very young grains, increased to a maximum at about 25 days after anthesis, then returned to a low level as the grain matured. it appeared to be located in the aleurone layer. a procedure was developed for obtaining partially purified preparations of ... | 1982 | 16662187 |
| rotation of cells in an alternating electric field: theory and experimental proof. | protoplasts of avena sativa rotate in an alternating electric field provided that at least two cells are located close to each other. an optimum frequency range (20 to 30 khz) exists where rotation of all cells exposed to the field is observed. below and above this frequency range, rotation of some cells is only occasionally observed. the angular velocity of rotation depends on the square of the electric field strength. at field strengths above the value leading to electrical breakdown of the ce ... | 1982 | 7097755 |
| characterization of the inhibition of k absorption in oat roots by salicylic acid. | the phenolic compounds salicylic acid (o-hydroxybenzoic acid) and ferulic acid (4-hydroxy-3-methoxycinnamic acid) inhibited k(+) ((86)rb(+)) absorption in excised oat (avena sativa l. cv. goodfield) root tissue. salicylic acid was the most inhibitory. the degree of inhibition was both concentration- and ph-dependent. with decreasing ph, the inhibitory effect of the phenolic increased. during the early stages of incubation, the time required to inhibit k(+) absorption was also ph- and concentrati ... | 1981 | 16662106 |
| use of lilium longiflorum, cv. ace pollen germination and tube elongation as a bioassay for the hepatocarcinogens, aflatoxins. | although various animal tissues are used for bioassay of aflatoxins (b1, b2, g1, g2), a rapid bioassay dependent upon a plant part's response does not exist. both pollen germination (g) and tube elongation (te) were enhanced in a 3.0 mm kh2po4 (k)-containing but afb1-lacking, modified dickinson's medium. the b1 did not affect g when k was withheld but k supplementation impaired g above 15 micrograms/ml b1. without k, 5-20 stimulated but 25 and 30 micrograms/ml b1 inhibited te which was suppresse ... | 1981 | 7274186 |
| chlorophyll biosynthesis by mesophyll protoplasts and plastids from etiolated oat (avena sativa l.) leaves. | the uptake of [1-(3)h]geranylgeranyl diphosphate (ggpp) into protoplasts and intact etioplasts and the metabolic interconversion therein was studied after a 2 min pulse of white light. the chlorophyll synthetase reaction, chlide+ggpp→chlgg, was taken as a natural probe for the etioplast compartment. this reaction yields labeled chlgg and, by hydrogenation, labeled chlp, when [1-(3)h]ggpp receives access to the etioplast stroma. it was found that penetration across the plastid envelope was rapid ... | 1981 | 24302319 |
| changes in endogenous gibberellins and the metabolism of [h]ga(4) after geostimulation in shoots of the oat plant (avena sativa). | the recovery from "lodging," or bending over, by shoots of 42-day-old avena sativa plants is controlled primarily by a negatively geotropic differential growth of the lower halves of the p-1 node-pulvinus and the base of the p-1 internode, relative to the upper halves. although geostimulation causes a significant reduction in p-1 internode length, dry matter accumulation in the p-1 node-pulvinus is increased, apparently at the expense of the sheath. recovery to an angle of 30 degrees is associat ... | 1981 | 16661788 |
| phytochrome control of two low-irradiance responses in etiolated oat seedlings. | light-induced coleoptile stimulation and mesocotyl suppression in etiolated avena sativa (cv. lodi) has been quantitated. etiolated seedlings showed the greatest response to light when they were illuminated 48 to 56 hours after imbibition. two low-irradiance photoresponses for each tissue have been described. red light was 10 times more effective than green and 1,000 times more effective than far red light in evoking these responses. the first response, which resulted in a 45% mesocotyl suppress ... | 1981 | 16661745 |
| covalent labelling of the nadph: protochlorophyllide oxidoreductase from etioplast membranes with [3h]n-phenylmaleimide. | [3h]n-phenylmaleimide has been used to covalently label in a specific manner the substrate-protected thiol groups of the enzyme protochlorophyllide reductase. in membrane preparations from oat (avena sativa) and runner-bean (phaseolus vulgaris) seedlings, two related peptides of mol.wts. 35000/37000 and 34000/35000 respectively and showing properties expected of the reductase have been identified, whereas the same technique with barley (hordeum vulgare) extracts resulted in labelling a single pe ... | 1981 | 7306063 |
| fusion of avena sativa mesophyll cell protoplasts by electrical breakdown. | studies with the light microscope were carried out on mesophyll cell protoplasts of avena sativa which had been made to undergo fusion by reversible electrical breakdown of the cell membrane. in order to establish close membrane contact between the cells, an important prerequisite for fusion, a method known as dielectrophoresis was used. in an inhomogeneous alternating electrical field the protoplasts adhere to the electrodes and to each other in the direction of the field lines. the cells which ... | 1981 | 7213711 |
| physicochemical differences between the red- and the far-red-absorbing forms of phytochrome. | we investigated some of the chemical and physical differences between the red-absorbing (pr) and far-red-absorbing (pfr) forms of immunoaffinity-purified, undegraded oat (avena sativa l., ev. garry) phytochrome. both pr and pfr had identical surface charges as measured by isoelectric focusing and identical secondary structure as judged from their circular dichroic spectra. modification of specific amino acid residues, however, revealed some chemical differences between pr and pfr. compared to pr ... | 1981 | 7213624 |
| glycerolipid synthesis in avena leaves during greening of etiolated seedlings ii. α-linolenic acid synthesis. | to determine the synthesis of α-linolenic acid esterified to galactolipids, etiolated leaves from avena sativa l. were fed with [1-(14)c]acetate for the first 3 hr of greening, and the redistribution of (14)c incorporated into the fatty acid moieties of lipid classes was examined during a 21-hr chase. phosphatidylcholine (pc) was most heavily labeled, but lost a large portion of its (14)c during the chase. galactolipids, such as monogalactosyl-diglyceride (mgdg) and digalactosyldiglyceride (dgdg ... | 1980 | 25385976 |
| glycerolipid synthesis in avena leaves during greening of etiolated seedlings i. lipid changes in leaves. | etiolated seedlings of avena sativa l. were illuminated under fluorescent light of 1,500 lux at 25°c and the lipid changes in their first leaves and isolated plastids were followed during 24 hr of greening. lipid changes were divided into a degradation phase [0 hr of illumination (hr-l) to 3 hr-l] and a synthetic phase (3 hr-l to 24 hr-l). in the degradation phase, which paralleled prolamellar body transformation in the plastids, both plastidic lipids, monogalactosyldiglyceride (mgdg), digalacto ... | 1980 | 25385975 |
| effects of peeling on the surface structure of the avena coleoptile: implications for hormone research. | coleoptiles of oats (avena sativa l.) are often peeled in order to observe hormone-enhanced acidification of the external medium. it is shown by means of the scanning electron microscope that peeling largely removes a single layer of cells, the epidermis with its cuticle. strips of intact and damaged epidermal cells remain, but most of the newly exposed surface is composed of cortical cells. the cortical face is relatively intact, except that some cells appear punctured and some are broken when ... | 1980 | 24306888 |
| rapid separation of the plastid, mitochondrial, and cytoplasmic fractions from intact leaf protoplasts of avena : determination of in vivo atp pool sizes during greening. | purified intact protoplasts were isolated from etiolated and greening leaves of avena sativa. they were ruptured by forcing them through a 20-μm aperture nylon net and immediately thereafter fractionated into a pure pellet of plastids (well above 70% of total plastids), a layer of mitochondria only slightly contaminated by other cellular constituents (about 50% of total mitochondria), and a cytoplasmic supernatant. this was achieved within 60 s by an integrated method of homogenation of protopla ... | 1980 | 24306801 |
| hormonal regulation of lateral bud (tiller) release in oats (avena sativa l.). | stem segments containing a single node and quiescent lateral bud (tiller) were excised from the bases of oat shoots (cv. ;victory') and used to study the effects of plant hormones on release of lateral buds and development of adventitious root primordia. kinetin (10(-5) and 10(-6) molar) stimulates development of tillers and inhibits development of root primordia, whereas indoleacetic acid (iaa) (10(-5) and 10(-6) molar) causes the reverse effects. abscisic acid strongly inhibits kinetin-induced ... | 1980 | 16661589 |
| phytochrome pelletability induced by irradiation in vivo: mixing experiments. | samples of irradiated and control avena sativa shoot tissue were homogenized together to determine whether, during homogenization phytochrome from irradiated tissue can bind to the particulate material simultaneously extracted from the control tissue. the level of phytochrome pelletability for such mixed tissue homogenizations is equal to: (a) the values obtained when the extracts from separate homogenizations of the two batches of tissue are mixed and then centrifuged; and (b) the arithmetic me ... | 1980 | 16661550 |
| protein patterns in the oat coleoptile as influenced by auxin and by protein turnover. | synthesis of growth-limiting proteins (glp) is required for continued auxin-induced elongation of oat (avena sativa l.) coleoptiles. in order to determine whether glp synthesis is dependent or independent of auxin, a double-labeling ratio technique, coupled with disc-gel electrophoresis, has been used to assess the effect of auxin on the pattern of protein synthesis. sections were peeled to enhance amino-acid uptake; proteins were labeled with [(14)c]- or [(3)h] leucine in the presence or absenc ... | 1980 | 24310183 |
| influence of anaerobiosis on chlorophyll biosynthesis in greening oat seedlings (avena sativa l.). | the influence of anaerobiosis for 0.5 to 15 hours on the last steps of chlorophyll biosynthesis of etiolated oat seedlings was investigated. phototransformation of protochlorophyllide to chlorophyllide is only slightly reduced and esterification of chlorophyllide is slightly increased by pretreatment under anaerobic conditions. pretreated plants accumulate the geranylgeraniol ester of chlorophyllide rather than the phytol ester. enzymic hydrogenation of the esterifying alcohol geranylgeraniol to ... | 1980 | 16661480 |
| analysis of genetic changes in radiated and non-radiated bulk oat (avena sativa l.) populations. | in both radiated and non-radiated oat populations inbreeding coefficients increased more slowly than was expected on the assumption of full selfing and equal selective values for homozygotes and heterozygotes. assuming 1% outcrossing for oats and a selective value of 1.0 for the mean, the heterozygotes for two loci governing crown rust reaction have an advantage of 50% over the homozygotes. this study supports previous observations that the heterozygote often has a decided advantage in predomina ... | 1980 | 24305854 |
| isolation and identification of a senescence-promoting substance from wormwood (artemisia absinthium l.). | the senescence-promoting substance of wormwood (artemisia absinthium l.) as detected by the oat (avena sativa l. cv "victory") leaf assay has been identified as (-)-methyl jasmonate, methyl (1s, 2r)-3-oxo-2-(2'-cis-pentenyl)-cyclopentane-1-acetate, by gas-liquid chromatography-mass spectrometry and optical rotatory dispersion. its senescence-promoting effect was much stronger than that of abscisic acid, and even at such a low concentration as 1 to 2.5 micrograms per milliliter, it could complete ... | 1980 | 16661414 |
| detection and partial characterization of activity of chlorophyll synthetase in etioplast membranes. | the esterification of chlorophyllide a was investigated an irradiated etioplast-membrane fractions ('broken etioplasts') from oat seedlings (avena sativa l.). as a substrate, [1(-3)h]geranylgeraniol and its monophosphate and diphosphate derivatives were prepared by chemical synthesis. geranylgeraniol and its monphosphate derivative are incorporated into chlorophyll only in the presence of atp whereas the diphosphate derivative is incorporated also without atp. the yield of esterified chlorophyll ... | 1980 | 7408876 |
| the effect of light on the production of ethylene from 1-aminocyclopropane-1-carboxylic acid by leaves. | white light inhibits the conversion of 1-amino-cyclopropane-1-carboxylic acid (acc) in discs of green leaves of tobacco (nicotiana tabacum l.) and segments of oat (avena sativa l.) leaves by from 60 to 90%. etiolated oat leaves do not show this effect. the general nature of the effect is shown by its presence in both a mono- and a dicotyledon. since the leaves have been grown and pre-incubated in light, yet can produce from 2 to 9 times as much ethylene in the dark as in the light, it follows th ... | 1980 | 24306252 |
| metabolism of oat leaves during senescence: vi. changes in atp levels. | the atp content of 7-day-old avena sativa leaves during senescence in dark and in light, and after treatment with cytokinins and other reagents, has been determined by the luciferin-luciferase method. special care was taken to avoid decomposition of the atp, and a detailed procedure is presented for atp analysis at the picomole level. preliminary experiments with several inhibitors of photophosphorylation suggest, though not conclusively, that the delaying effect of light on senescence is mediat ... | 1980 | 16661296 |
| on the use of avena protoplasts to study chloroplast development. | different methods were tested to isolate protoplasts from etiolated, partially greened, and light-grown leaves of avena sativa. preparations with high yields and high photosynthetic capacities (time of illumination ≧4 h) were obtained when small transverse leaf segments were incubated for 2 h at 30°c in 2% cellulysin (calbiochem), 0.6 m mannitol, and 0.5% bovine serum albumin (bsa) at ph 5.6, without shaking. as measured by light-dependent o2 evolution or fixation of labeled bicarbonate, protopl ... | 1980 | 24311173 |
| electrical field effects induced in membranes of developing chloroplasts. | etioplasts, etiochloroplasts, and chloroplasts of avena sativa l. purified on a percoll gradient were subjected to increasing electric field strengths in the orifice of a hydrodynamically focussing coulter counter. the change in resistance of the orifice when an organelle is present correlates well with the size of the plastid for field strengths up to about 3.5 kv cm(-1). beyond this field strength, depending on the size of the organelle, the size is underestimated. the underestimation of the s ... | 1980 | 24311160 |
| partial characterization of undegraded oat phytochrome. | we characterized immunoaffinity-purified, undegraded oat (avena sativa l., cv. garry) phytochrome by several physicochemical techniques. phytochrome, of greater than 98% purity [hunt, r. e., & pratt, l. h. (1979) plant physiol. 64, 332-336], existed in solution as a dimer of its 118 000-dalton monomers and had a full complement of the typical amino acids with about 35% nonpolar residues, 115 carboxylic acid groups per monomer, and an average of one phosphate per monomer. although the dimer was n ... | 1980 | 7352993 |
| control of mitochondrial activities by phytochrome during greening. | mitochondria isolated from 7-day old darkgrown avena sativa l. (var. arnold) laminae given 5 min illumination of red light, followed by varying lengths of darkness up to 3 h, showed at least a twofold increase in the rates of both nadh-dependent oxygen consumption and respiratory chain phosphorylation over those of mitochondria isolated from unilluminated tissue. similar organelles, isolated from tissue given either far-red or red followed by far-red pretreatment, exhibited rates of both functio ... | 1979 | 24311037 |
| nonhormonal induction of h efflux from plant tissues and its correlation with growth. | when the esterase substrate alpha-naphthyl acetate is added to segments from coleoptiles of oat (avena sativa l., var. victory) or corn (zea mays l., bear hybrid wf 9 x 38) or to roots of lentil (lens culinaris med.), it is rapidly taken up and hydrolyzed to alpha-naphthol and acetic acid. this technique was used to generate intracellular acid and to study the effect of its efflux on growth. with corn coleoptile segments, treatment with alpha-naphthyl acetate induced more rapid and more prolonge ... | 1979 | 16592739 |
| cyanide inhibition of acid-induced growth in avena coleoptile segments. | the comparative effects of metabolic inhibitors on acid- and auxininduced growth in oat (avena sativa l. var. victory) coleoptile segments have been examined. acid (ph 4)-induced growth in both peeled and unpeeled segments is inhibited by 1 millimolar kcn when added at the time of acidification. kcn inhibits total acid-induced growth by 59 and 76%, respectively, in peeled and nonpeeled segments during the first 60 minutes. the growth rate of cyanide-treated tissue drops to zero or near zero in b ... | 1979 | 16661034 |
| phytochrome immunoaffinity purification. | we have developed a phytochrome immunoaffinity purification procedure that yields undegraded oat (avena sativa l., cv. garry) phytochrome of greater than 98% purity within 2 hours when starting with a brushite-purified preparation. immunoaffinity-purified phytochrome, except for its greater purity, is indistinguishable from conventionally purified phytochrome by gel exclusion chromatography, isoelectric focusing, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. we have also used th ... | 1979 | 16660959 |
| short term phytochrome control of oat coleoptile and pea epicotyl growth. | continuous recordings of the effect of light on oat (avena sativa l. cv. victory) coleoptile and pea (pisum sativum l. cv. alaska) epicotyl growth were made. using a single excised coleoptile 10 minutes of red light was found to promote growth after a latent period of 46 minutes. the stimulation was transient and was not far red-reversible. blue and far red light also promoted growth with similar kinetics. the action of continuous red or far red light was similar to that of 10-minute light. the ... | 1979 | 16660744 |
| kinetics of mitochondrial phosphate transport and rates of respiration and phosphorylation during greening of etiolated avena leaves. | using the technique of silicone oil filtration of organelles and the inhibitor stop method, the kinetics of transport of inorganic phosphate across the inner mitochondrial membrane were tested in relation to different stages of greening (0 to 24 h) of etiolated laminae of avena sativa l., and compared to the rates of oxygen consumption and atp formation. the results demonstrate that there is a pronounced increase in phosphate transport after 3 h of greening, reaching values for vmax (about 17 μm ... | 1979 | 24407321 |
| protein synthesis and auxin-induced growth: inhibitor studies. | we have compared the effects of cycloheximide (chi) and two other rapid and effective inhibitors of protein synthesis, pactamycin and 2-(4-methyl-2,6-dinitroanilino)-n-methyl proprionamide (mdmp), on protein synthesis, respiration, auxin-induced growth and h(+)-excreation of avena sativa l. coleoptiles. all three compounds inhibit protein synthesis without affecting respiration. the effectiveness of the inhibitors against h(+)-excretion and growth correlates with their ability to inhibit protein ... | 1979 | 24317859 |
| studies on lysine analogs, aspartate-derived amino acids, and attempted mutant selection on oat seedlings. | the lysine analogs s-2-aminoethyl-l-cysteine (aec) and dl-δ-hydroxylysine (dhl) caused severe growth inhibition in dark-grown oat seedlings (avena sativa l. and a. nuda l.) at similar concentrations while l-lysine methyl ester (lme) had little effect. lysine, arginine, and ornithine reversed the inhibition caused by aec and dhl, the order of effectiveness being lysine>arginine>ornithine. of aspartate-pathway amino acids, tested individually and in combinations for inhibitory effects on seedling ... | 1979 | 24317756 |
| effects of osmotic stress on polar auxin transport in avena mesocotyl sections. | segments of mesocotyls of avena sativa l. transported [1-(14)c]indol-3yl-acetic acid (iaa) with strictly basipetal polarity. treatment of the segments with solutions of sorbitol caused a striking increase in basipetal auxin transport, which was greatest at concentrations around 0.5 m. similar effects were observed with mannitol or quebrachitol as osmotica, but with glucose or sucrose the increases were smaller. polar transport was still detectable in segments treated with 1.2 m sorbitol. the eff ... | 1979 | 24317665 |
| comparison of reductions in adenosine triphosphate content, plasma membrane-associated adenosine triphosphatase activity, and potassium absorption in oat roots by diethylstilbestrol. | the possibility was investigated that diethylstilbestrol (des) inhibits potassium absorption in oat (avena sativa l. cv. goodfield) roots by inhibiting mitochondrial functions in addition to inhibiting the plasma membrane atpase. des at 10(-6) molar stimulated the mitochondrial atpase slightly, but higher concentrations had no effect. oxidative phosphorylation by isolated mitochondria was inhibited 50% by 2.6 x 10(-5) molar des; concentrations of 10(-4) molar or greater were completely inhibitor ... | 1979 | 16660692 |
| inhibition of adenosine triphosphatase activity of the plasma membrane fraction of oat roots by diethylstilbestrol. | diethylstibestrol (des) inhibited noncompetitively the atpase in the plasma membrane fraction from avena sativa l. cv. goodfield roots when assayed in the presence of mgso(4) or mgso(4) plus kcl. in the presence of mgso(4), 7.1x10(-5) molar des inhibited the enzyme 50%; whereas in the presence of mgso(4) and kcl, 1.3x10(-4) molar des was required for the same inhibition. dixon plots indicated that in the presence of mgso(4), one molecule of des bound to one molecule of atpase; however, in the pr ... | 1979 | 16660690 |
| effect of diethylstilbestrol on ion fluxes in oat roots. | effects of diethylstilbestrol (des) on ion fluxes in oat roots (avena sativa l.) were investigated by measuring k(+) and cl(-) absorption and k(+) efflux. des rapidly decreased the absorption of k(+) ((86)rb) and (36)cl(-) by excised roots; 10(-4) molar des inhibited cl(-) absorption in 1 minute and k(+) absorption in 1 to 2 minutes. with a 10-minute incubation period, k(+) and cl(-) absorption were inhibited 50% by 1.1x10(-5) molar and 8.4x10(-6) molar des, respectively. treatment for 3 minutes ... | 1979 | 16660689 |
| red light and auxin effects on rubidium uptake by oat coleoptile and pea epicotyl segments. | apical segments of etiolated oat (avena sativa l. cv. victory) coleoptiles showed enhanced uptake of [(86)rb(+)] when tested 30 minutes after a 5-minute red irradiation. the response was partly reversible by far red light. uptake was sensitive to carbonyl cyanide m-chlorophenyl hydrazone, but not to isotonic mannitol. indoleacetic acid (10(-7) molar) caused a very pronounced and rapid stimulation of uptake. basal coleoptile segments also exhibited a red light-enhanced uptake, but not an effect o ... | 1979 | 16660665 |
| use of lipophilic cations to measure the membrane potential of oat leaf protoplasts. | uptake of the lipophilic cation triphenylmethylphosphonium into mesophyll protoplasts of oat (avena sativa l. cv. "garry") approaches equilibrium at 3 to 4 hours. the resulting external and internal concentrations are then used with the nernst equation to obtain a membrane potential of -62 millivolts, inside negative. potentials calculated in this manner are depolarized by adding 2 mm sodium azide and 50 mum carbonyl cyanide m-chlorophenylhydrazone as well as by increasing the external proton an ... | 1978 | 16660641 |
| phytochrome destruction: apparent inhibition by ethylene. | phytochrome destruction begins immediately following actinic irradiation of 4-day-old, dark-grown oat (avena sativa l., cv. garry) shoots grown in open containers. when grown in closed containers, otherwise identical oat shoots exhibit a delay of about 40 minutes between irradiation and the onset of destruction. this delay can be attributed to accumulation of ethylene by several criteria, including elimination of the delay by mercuric perchlorate. these data provide an explanation for otherwise ... | 1978 | 16660639 |
| capping structures at the 5'-terminus of polyadenylated ribonucleic acid in avena coleoptiles. | evidence is presented for the occurrence of 5'-terminal capping structures in the polyadenylated rna of oat (avena sativa) coleoptiles. these structures are composed of an inverted terminal nucleoside containing the modified base 7-methylguanine which is joined 5' to 5' with a second (penultimate) nucleoside by means of three phosphate groups in two pyrophosphate linkages. the penultimate nucleoside is joined to the remainder of the rna molecule by a conventional 3',5' phosphodiester bond. a sig ... | 1978 | 16660619 |
| kinetics of membrane transport during chloroplast development. | in the course of plastid development there are changes in the permeability of the envelope membranes. an investigation of the kinetics of transport with largely uncontaminated and intact etioplast/etiochloroplast preparations from greening avena sativa laminae demonstrates: (a) that etioplasts already possess specific translocators for the transporation of orthophosphate, dihydroxyacetone phosphate, 3-phosphoglycerate ("phosphate translocator"), and dicarboxylic acids ("dicarboxylate translocato ... | 1978 | 16660596 |
| subunit structure and composition of oat seed globulin. | oat (avena sativa l.) seed globulin was extracted from ground caryopses with 1 m nacl, 0.05 m tris(hydroxymethyl)aminoethane (ph 8.5) at room temperature. the globulin had a sedimentation constant of 12.1, and a molecular weight of 322,000, as determined by analytical ultracentrifugation. the globulin could be separated into two major subunits by sodiumdodecyl sulfate polyacrylamide gel electrophoresis. molecular weights of the subunits were 21,700 (alpha) and 31,700 (beta), and they were presen ... | 1978 | 16660548 |
| effect of abscisic acid on the gain of the feedback loop involving carbon dioxide and stomata. | gains of the feedback loops involving intercellular co(2) concentration on one hand, and co(2) assimilation and stomata on the other (= assimilation loop with gain [g(a)] and conductance loop with gain [g(g)]) were determined in detached leaves of amaranthus powelli s. wats., avena sativa l., gossypium hirsutum l., xanthium strumarium l., and zea mays in the absence and presence of 10(-5)m (+/-) abscisic acid (aba) in the transpiration stream. determinations were made for an ambient co(2) concen ... | 1978 | 16660528 |
| regulation of glucose metabolism and cell wall synthesis in avena stem segments by gibberellic acid. | gibberellic acid (ga) stimulated both the elongation of avena sativa stem segments and increased synthesis of cell wall material. the effects of ga on glucose metabolism, as related to cell wall synthesis, have been investigated in order to find specific events regulated by ga. ga caused a decline in the levels of glucose, glucose 6-phosphate, and fructose 6-phosphate if exogenous sugar was not supplied to the segments, whereas the hormone caused no change in the levels of glucose 6-phosphate, f ... | 1978 | 16660524 |
| cadmium alteration of root physiology and potassium ion fluxes. | segments of oat (avena sativa l.) roots which had been exposed to 1 millimolar cdso(4) in quarter-strength hoagland no. 1 solution exhibited decreased respiratory rates, atp levels, membrane-bound atpase activity, and reduced k(+) fluxes. respiration and atp levels were decreased after a 2-hour treatment with 1 millimolar cdso(4) to 65 and 75%, respectively, of control rates. a membrane-bound, mg(2+)-dependent, k(+)-stimulated acid atpase was rapidly inhibited to 12% of control activity in the p ... | 1978 | 16660477 |
| dual mechanisms in polyamine-mediated control of ribonuclease activity in oat leaf protoplasts. | dibasic amino acids and polyamines added to oat (avena sativa l.) leaf protoplast isolation media decrease the rnase activity of extracted protoplasts relative to controls. this effect, which is manifested even when the added polyamine is removed by exhaustive dialysis prior to assay, is due to a prevention of the rise in rnase activity which usually follows protoplast isolation. polyamines, but not dibasic amino acids, also decrease rnase activity in vitro. this in vitro effect seems to result ... | 1978 | 16660458 |
| evidence for amino acid-h co-transport in oat coleoptiles. | microelectrode and tracer techniques were used to test for possible amino acid-h(+) co-transport in coleoptiles of avena sativa l. cv. "garry." the amino acid analogue alpha-aminoisobutyric acid (aib) caused transient depolarization of the membrane potential. the absolute magnitude of the maximum depolarization was affected by the same factors that affected aib transport. both increased with higher concentrations of aib, increased with higher acidities in the medium, and were enhanced by indolea ... | 1978 | 16660429 |
| alkylguanidine inhibition of ion absorption in oat roots. | the effect of various alkylguanidines on ion absorption and energy metabolism in oat (avena sativa cv. goodfield) roots has been investigated. of several alkylguanidines tested, octylguanidine was the most effective inhibitor of both k(+) and cl(-) absorption by excised roots. at 225 mum octylguanidine, the transport of both ions was inhibited within 60 seconds and to a similar extent. octylguanidine inhibited mitochondrial oxidative phosphorylation and mitochondrial adenosine 5'-triphosphatase ... | 1978 | 16660414 |
| proteases of senescing oat leaves: ii. reaction to substrates and inhibitors. | two proteases isolated from senescent oat (avena sativa) leaves have been subjected to further study. one of these, an acid protease active at ph 4.2, is inhibited by phenylmethylsulfonyl fluoride (pmsf) but not by iodoacetamide (iac). the other, active at ph 6.6, is inhibited by both pmsf and iac. these results, together with previously reported evidence that mercaptoethanol stimulates the activity of only the neutral protease, are taken to indicate that the acid protease is probably of the ser ... | 1978 | 16660324 |
| destruction and possible de novo synthesis of phytochrome in subcellular fractions of laminae from avena sativa l. | phytochrome was determined in etiolated laminae of avena satival. either without pretreatment or after 5 min of red irradiation followed by different periods of darkness (0-24 h). at given intervals laminae were homogenized and phytochrome was determined spectrophotometrically in the total homogenate and in purified etioplasts and mitochondria. enhanced specific activity of phytochrome was found in all fractions after the irradiation in comparison to dark controls. phytochrome destruction was ob ... | 1978 | 24414872 |
| phytochrome photoreversibility: empirical test of the hypothesis that it varies as a consequence of pigment compartmentation. | phytochrome of oat (avena sativa l., cv. garry) coleoptile cells in the red-light-absorbing form, pr, is diffusely distributed while after conversion to the far-red-light-absorbing form, pfr, it is observed only in very small areas within the cell. comparison of phytochrome photoversibility measurements to the distribution of the pigment within the cell indicates that the spectral assay is not influenced by the observed compartmentalization of the chromoprotein. however, the observed compartment ... | 1978 | 24414766 |
| a comparison of regenerated cell walls in tobacco and cereal protoplasts. | four independent kinds of observations indicate that the cell wall regenerated by oat (avena sativa l.) and corn (zea mays l.) protoplasts in culture is less well developed than that regenerated by tobacco (nicotiana tabacum l.) protoplasts. following wall regeneration the cereal protoplasts remained susceptible to osmotic shock upon transfer to water, showed great enlargement, stained poorly with calcofluor white, and maintained a positive internal electrical potential. the development of a neg ... | 1978 | 24414155 |
| effects of fusicoccin on the activity of a key ph-stat enzyme, pep-carboxylase. | the phytotoxin fusicoccin (fc) causes rapid synthesis of malate in coleoptile tissues, presumably via phosphoenolpyruvate (pep) carboxylase coupled with malate dehydrogenase. the possibility that fc directly affects pep carboxylase in avena sativa l. and zea mays l. coleoptiles was studied and rejected. the activity of this enzyme is unaffected by fc whether fc is added in vitro or a pretreatment to the live material. fc does not change the sensitivity of the enzyme to bicarbonate or malate. the ... | 1978 | 24414104 |
| rapid auxin- and fusicoccin-enhanced rb(+) uptake and malate synthesis in avena coleoptile sections. | the short-term effects of auxin (indole-3-acetic acid) and fusicoccin (fc) on rb(+) uptake and malate accumulation in avena sativa l. coleoptile sections have been investigated. fc stimulates (86)rb(+) uptake within 1 min while auxin-enhanced uptake begins after a 15-20-min lag period. auxin has little or no effect on (86)rb(+) uptake at external phs of 6.0 or less, but substantial auxin effects can be observed in the range of ph 6.5 to 7.5. competition studies indicate that the uptake mechanism ... | 1978 | 24414103 |
| spectrophotometric phytochrome measurements in light-grown avena sativa l. | phytochrome was studied spectrophotometrically in avena sativa l. seedlings that had been grown for 6 d in continous white fluorescent light from lamps. greening was prevented through the use of the herbicide san 9789. when placed in the light, phytochrome (ptot) decreased with first order kinetics (τ1/2 ≈ 2 h) but reached a stable low level (≈2.5% of the dark level) after 36 h. this concentration of phytochrome remained constant in the light and during the initial hours of a subsequent dark per ... | 1978 | 24408470 |
| the contribution of tonoplast and plasma membrane to the electrical properties of a higher-plant cell. | the cytoplasm of subepidermal parenchyma cells of avena sativa l. coleoptiles was collected at one end of the cell by centrifugation. the electrical properties of both plasmalemma and tonoplast were then examined with microelectrodes inserted into both cytoplasm and vacuole of the same cell. the input resistance of the cytoplasm measured with either electrode was 7.5±0.8 mω while that of the vacuole measured with the single vacuolar electrode and a bridge circuit was 29.2±3.1 mω. the latter valu ... | 1978 | 24408463 |
| comparison of three methods for measuring electrical resistances of plant cell membranes. | the reliability of two different membrane resistance-measuring methods that use a single intracellular microelectrode was tested against a conventional method that uses two intracellular microelectrodes. the first single-electrode method used a single square current pulse and required a constant microelectrode resistance. this method was unreliable because the electrode resistance changed markedly on cell penetration and changed with time within the cell. the second method used a high frequency ... | 1977 | 16660164 |
| beta-d-glucan of avena coleoptile cell walls. | a specific glucanase was used to liberate a noncellulosic beta-d-glucan from isolated cell walls of avena sativa coleoptile tissue. cell walls of this tissue contain as much as 7 to 9 mg of glucan/100 mg of dry wall. because of the specific action pattern of the enzyme, a linkage sequence of.. 1 --> 4 glc 1 --> 3 glc 1 --> 4 glc.. is indicated and the predominance of trisaccharide and tetrasaccharide as hydrolytic products suggests a rather regular repeating pattern in the polysaccharide. the tr ... | 1977 | 16660149 |
| stabilization of oat leaf protoplasts through polyamine-mediated inhibition of senescence. | protoplasts isolated from avena sativa l. leaves undergo progressive senescence when incubated aseptically in 0.6 m mannitol with or without added nutrients. this senescence is manifested by morphological deterioration and ultimate lysis of protoplasts, by a decrease in incorporation of [(3)h]uridine and [(3)h]leucine into macromolecules, and by a sharp increase in ribonuclease activity.the presence in the incubation medium of l-arginine, l-lysine, certain polyamines related to these amino acids ... | 1977 | 16660139 |
| occurrence and properties of polygalacturonase in avena and other plants. | polygalacturonase activity has been detected in a number of plants including seedlings of phaseolus vulgaris, zea mays, avena sativa, and pisum sativum. particular emphasis was placed on characterizing the enzyme from oat seedlings. this enzyme is solubilized by 0.2 m nacl, and its activity is highest near the apical tips of oat coleoptiles. it has a ph optimum between 5 and 5.5 and is activated by ca(2+), with an optimal concentration of 0.4 mm. cd(2+) also activates the enzyme but less effecti ... | 1977 | 16660135 |
| isolation and purification of an alpha-mannosidase from coleoptiles of avena sativa. | an alpha-mannosidase has been purified from the coleoptiles of avena sativa l. var. segrehavre. the enzyme, which is tightly associated with the cell wall, was solubilized with 3 m licl. the purification involves precipitation with (nh(4))(2)so(4), gel filtration, ion exchange chromatography, and isoelectric focusing. the enzyme appears homogeneous when chromatographed on disc gels and on isoelectric focusing gels. the enzyme runs as a single protein of constant specific activity when chromatogr ... | 1977 | 16660119 |
| responses of enzymically isolated aleurone cells of oat to gibberellin a(3). | oat (avena sativa l.) aleurone layer cells (spheroplasts) were isolated by maceration of the aleurone layer with a mixture of commercially available cellulase and pectinase. about 20% of the cells present in intact layers were released as spheroplasts and 79 +/- 9% of the spheroplast population was viable as judged by methylene blue staining. the spheroplasts became disorganized in solutions containing less than 0.4 md-mannitol. when the spheroplasts were incubated for 48 hours, total activities ... | 1977 | 16660114 |
| effects of indoleacetic acid on the quantity of mitochondria, microbodies, and plastids in the apical and expanding cells of dark-grown oat coleoptiles. | we determined the number of mitochondria, microbodies, and plastids in dark-grown oat (avena sativa) coleoptiles following incubation in indoleacetic acid (iaa) for a period of 60 minutes at 6-minute intervals. in the apical outer epidermis of coleoptiles, the mitochondria increased from 31.4 to 35 per cell section with a 6-minute incubation in iaa, and this trend persisted over the 60-minute incubation. neither the microbodies, plastids, nor the dicytosomes (gawlik and miller 1974 plant physiol ... | 1977 | 16660086 |
| chloroplast phosphofructokinase: i. proof of phosphofructokinase activity in chloroplasts. | ammonium sulfate fractionation of an extract from the leaves of spinach (spinacia oleracea l.) produced two fractions of phosphofructokinase activity, the first stimulated by inorganic phosphate and the second inhibited by inorganic phosphate. only the second fraction was obtained from similar treatment of an extract of isolated spinach chloroplasts. the two fractions differed distinctly with respect to kinetics for the substrate fructose 6-phosphate. evidence for these two types of phosphofruct ... | 1977 | 16660078 |