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dissecting the diphenylene iodonium-sensitive nad(p)h:quinone oxidoreductase of zucchini plasma membrane.quinone oxidoreductase activities dependent on pyridine nucleotides are associated with the plasma membrane (pm) in zucchini (cucurbita pepo l.) hypocotyls. in the presence of nadph, lipophilic ubiquinone homologs with up to three isoprenoid units were reduced by intact pm vesicles with a km of 2 to 7 [mu]m. affinities for both nadph and nadh were similar (km of 62 and 51 [mu]m, respectively). two nad(p)h:quinone oxidoreductase forms were identified. the first, labeled as peak i in gel-filtratio ...199712223742
protein transport into higher plant peroxisomes. in vitro import assay provides evidence for receptor involvement.peroxisome biogenesis requires that proteins be transported from their site of synthesis in the cytoplasm to their final location in the peroxisome matrix or membrane. glyoxysomes are a class of peroxisomes found primarily in germinating seedlings and are involved in mobilizing fatty acids via the glyoxylate cycle and the beta-oxidation pathway. we have used an in vitro assay to study the mechanism(s) of import of proteins into glyoxysomes. results from this assay indicate that the transport pro ...19979112774
root growth inhibition in boron-deficient or aluminum-stressed squash may be a result of impaired ascorbate metabolism.although cessation of growth is the most apparent symptom of boron deficiency, the biochemical function of boron in growth processes is not well understood. we propose that the action of boron in root meristems is associated with ascorbate metabolism. total inhibition of root growth in squash (cucurbita pepo l.) plants transferred to boron-free medium coincided with a major decrease (up to 98%) in the ascorbate concentration of root apices. under low-boron conditions, in which root growth was pa ...199612226437
cytoplasmic orientation of the naphthylphthalamic acid-binding protein in zucchini plasma membrane vesicles.polar transport of the plant hormone auxin is blocked by substances such as n-1-naphthylphthalamic acid (npa), which inhibit auxin efflux and block polar auxin transport. to understand how auxin transport is regulated in vivo, it is necessary to discern whether auxin transport inhibitors act at the intra- or extracellular side of the plasma membrane. populations of predominantly in-side-in plasma membrane vesicles were subjected to treatments that reverse the orientation. these treatments, which ...199612226399
variability of fatty acid content in pumpkin seeds (cucurbita pepo l.).pumpkin (cucurbita pepo l.) seed oil is a common salad oil which is produced in slovenia, hungary and the southern parts of austria. it is dark green and has a high content of free fatty acids. the seed itself can be eaten. due to its colour and the foam formation, the oil cannot be used for cooking. the content of vitamin e, especially gamma-tocopherol, is very high. the oil content of the pumpkin seed is about 50%. the variability in the oil content is very high resulting from a broad genetic ...19968873459
degradation pattern of photosystem ii reaction center protein d1 in intact leaves. the major photoinhibition-induced cleavage site in d1 polypeptide is located amino terminally of the de loop.photoinhibition-induced degradation of the d1 protein of the photosystem ii reaction center was studied in intact pumpkin (cucurbita pepo l.) leaves. photoinhibition was observed to cause the cleavage of the d1 protein at two distinct sites. the main cleavage generated an 18-kd n-terminal and a 20-kd c-terminal degradation fragment of the d1 protein. this cleavage site was mapped to be located clearly n terminally of the de loop. the other, less-frequent cleavage occurred at the de loop and prod ...19968756500
the n-1-naphthylphthalamic acid-binding protein is an integral membrane protein.n-1-naphthylphthalmic acid (npa)-binding protein is a plasmalemma (pm) protein involved in the control of cellular auxin efflux. we re-evaluated the spatial relationship of this protein with the pm of zucchini (cucurbita pepo l.) hypocotyls. first, triton x-114 partitioning indicated that the npa-binding protein was more hydrophobic than most pm proteins. second, the npa-binding activity was found to be resistant to proteolytic digestion in membranes. maximum concentrations of binding sites for ...199612226298
effects of pollen selection on progeny vigor in a cucurbita pepo x c. texana hybrid.we examined the effects of pollen selection for rapid pollen-tube growth on progeny vigor. first, we crossed a wild gourd (cucurbita texana) to a cultivated zucchini (cucurbita pepo cv 'black beauty') to produce an f1 and then an f2 generation. half of the f1 seeds were produced by depositing small loads of c. texana pollen onto the stigmas of c. pepo. these small pollen loads were insufficient to produce a full complement of seeds and, consequently, both the fast- and the slow-growing pollen tu ...199624166555
variability of vitamin e content in pumpkin seeds (cucurbita pepo l.).pumpkin (cucurbita pepo l.) seed oil is a common salad oil which is produced in the southern parts of austria, slovenia and hungary. it is dark green and has a high content of free fatty acids. due to its colour, the oil cannot be used for cooking. the content of vitamin e, especially gamma-tocopherol, is very high. the oil content of the pumpkin seed is about 50%. the seed itself can be eaten. therefore a pumpkin variety with high vitamin e content is desirable. the aim of this work was to find ...19968638429
polyamine binding to plasma membrane vesicles isolated from zucchini hypocotyls.the general features of [14c]spermidine binding to plasmalemma vesicles isolated from zucchini (cucurbita pepo l.) etiolated hypocotyls are reported in the present paper. the specific interaction of the polyamine with the plasma membranes was reversible and thermolabile, since it decreased by about 50% in the assay performed at 40[deg]c compared to that carried out on ice. on the contrary, nonspecific binding was unaffected by temperature. specific spermidine binding showed a ph dependence with ...199612226221
transcriptional regulation of hydroxypyruvate reductase gene expression by cytokinin in etiolated pumpkin cotyledons.to understand the mechanisms by which the expression of a specific gene is modulated by cytokinin, the regulation of hydroxypyruvate reductase (hpr) transcript levels by n6-benzyladenine (ba) in etiolated pumpkin (cucurbita pepo l. cv. halloween) cotyledons was investigated. a pumpkin hpr cdna was generated by reverse transcriptase-polymerase chain reaction and its nucleotide sequence was determined. an antisense hpr rna was prepared for rnase protection analysis of hpr-mrna expression patterns ...19968580766
galactinol synthase from kidney bean cotyledon and zucchini leaf. purification and n-terminal sequences.galactinol synthase (gs) was purified 1591-fold with a 3.9% recovery from the cotyledon of kidney bean (phaseolus vulgaris) by a novel scheme consisting of ammonium sulfate fractionation followed by diethylaminoethyl, affi-gel blue, and udp-hexanolamine affinity chromatography. the purified enzyme had a specific activity of 8.75 mumol mg-1 min-1, a ph optimum of 7.0, and requirements for manganese ion and dtt. the enzyme exhibited a km = 0.4 mm for udp-galactose and a km = 4.5 mm for myo-inosito ...19957480343
in search of a reversible stage of photoinhibition in a higher plant: no changes in the amount of functional photosystem ii accompany relaxation of variable fluorescence after exposure of lincomycin-treated cucurbita pepo leaves to high light.pumpkin (cucurbita pepo l.) leaves in which chloroplast protein synthesis was inhibited with lincomycin were exposed to strong photoinhibitory light, and changes in fo, fm, fv/fm and in the amount of functional photosystem ii (o2 evolution induced by saturating single-turnover flashes) were monitored during the high-light exposure and subsequent dark or low-light incubation. in the course of the photoinhibitory illumination, fm, fv/fm and the amount of functional ps ii declined continuously wher ...199524301535
determination of the quantum efficiency of photosystem ii and of non-photochemical quenching of chlorophyll fluorescence in the field.a newly developed portable chlorophyll fluorometer in combination with a special leaf clip holder was used for assessing photosynthetic activity of attached sun leaves of fagus sylvatica and cucurbita pepo under field conditions. during diurnal time courses, fluorescence yield, photosynthetic photon flux density (ppfd) incident on the leaf plane, and leaf temperature were measured and quantum efficiency of photosystem ii (ps ii), apparent relative electron transport rates, and non-photochemical ...199528306885
stability of japanese-lacquer-tree (rhus vernicifera) laccase to thermal and chemical denaturation: comparison with ascorbate oxidase.the thermal denaturation of laccase from the japanese lacquer tree (rhus vernicifera) was studied by differential scanning calorimetry. the endotherms of holo-laccase, type 2-cu-depleted laccase and apo-laccase were deconvoluted into two independent two-state transitions, providing evidence for a domain structure of the protein. the correlation of the two transitions with the bleaching of copper optical bands and the decrease of the transitions' enthalpy on cu removal show that the process invol ...19957702562
immunoglobulins anti-endonuclease 32 kda from cucurbita pepo var patissonina affect process of dna synthesis.immunoglobulins anti-endonuclease 32 kda inhibit dna synthesis. we observed that low concentrations of iggs (about 50 micrograms igg per 1 x 10(6) cell nuclei) temporary inhibit dna synthesis. this inhibition concerns only the synthesis of dna bound to the nuclear matrix (associated with isolated nuclear matrix). preincubation of cell nuclei of white bush with igg generates longer dna fragments than in controls. involvement of the 32 kda endonuclease or an endonuclease-65 kda protein complex fro ...19958588460
pattern and degree of methylation in ribosomal rna genes of cucurbita pepo l.methylation with respect to its degree and distribution throughout the 18s, 5.8s and 25s rrna gene clusters (rdna) and within single rdna repeats in seedlings of the higher plant cucurbita pepo l. (zucchini) was investigated. in this plant, which is characterized by several thousand repeats, at least 70% are completely or nearly completely methylated in cpgs and to a lower degree in cpnpgs. detailed methylation analysis revealed that a fraction of about 3-4% of all repeats is hypomethylated near ...19947811974
squash leaf glandular trichome volatiles: identification and influence on behavior of female pickleworm moth [diaphania nitidalis (stoll.)] (lepidoptera: pyralidae).fourteen volatile compounds occurring in leaf trichomes of yellow squash (cucurbita pepo l. cv. early prolific straightneck) were identified. these compounds accounted for 83.5% of the volatile matrix. ubiquitous constituents of the epidermis (myristic, palmitic, and stearic acids,n-tricosane, andn-pentacosane) accounted for 73.7%; these compounds were not bioassayed. the volatileso-,m-, andp-xylene, toluene, 2-heptanone, (r)-(+)- and (s)-(-)-limonene, and germacrene d were tested for their infl ...199424242732
effects of mixed cropping on a soil nematode community in honduras.nematode-resistant tropical legumes are effective in reducing populations of plant-parasitic nematodes when used in rotation systems. mixed cropping is a common practice of many small farmers in central america, but little is known about the effects of tropical legumes on nematode communities under these systems. to examine the effects of intercropping on the nematode fauna associated with squash (cucurbita pepo) and cucumber (cucumis sativa) in honduras, two field experiments were conducted to ...199319279824
sphingolipid long-chain base synthesis in plants (characterization of serine palmitoyltransferase activity in squash fruit microsomes).the activity of serine palmitoyltransferase (palmitoyl-coenzyme a [coa]:l-serine [ser]-c-palmitoyltransferase [decarboxylating], ec 2.3.1.50), the enzyme catalyzing the first step in the synthesis of the long-chain base required for sphingolipid assembly, has been characterized in a plant system. enzyme activity in a microsomal membrane fraction from summer squash fruit (cucurbita pepo l. cv early prolific straightneck) was assayed by monitoring the incorporation of l-[3h]ser into the chloroform ...199312232036
exhaustive removal of n-glycans from ascorbate oxidase: effect on the enzymatic activity and immunoreactivity.purified ascorbate oxidase from cucurbita pepo medullosa has been subjected to enzymatic deglycosylation using peptide n-glycosidase f. experimental conditions were chosen to obtain efficiently deglycosylated and active ascorbate oxidase: in particular, three different detergent solutions were added separately to the incubation mixtures prior to the peptide n-glycosidase f. the detergent solution made of 0.1% (w/v) sodium dodecyl sulphate + 0.5% (v/v) nonidet p-40 proved to be the only one effec ...19938130388
evidence for a single naphthylphthalamic acid binding site on the zucchini plasma membrane.the binding of [2,3,4,5,(n)-3h]n-1-napthylphthalamicacid ([3h]-npa) to zucchini (cucurbita pepo l.) plasma membranes was examined in detail using two different filtration assays and the results were rigorously analyzed by saturation curves, double-reciprocal plots, scatchard plots, hill plots, and the computer program ligand (p.j. munson, d. rodbard [1980] anal biochem 107: 220-239). to facilitate these analyses, a new assay that allows rapid and quantitative analysis of [3h]npa binding with hig ...199312231953
protein kinases in zucchini (characterization of calcium-requiring plasma membrane kinases).using an in situ phosphorylation assay with zucchini (cucurbita pepo l. cv dark green) seedling tissue, we have identified numerous polypeptides that are capable of acting as protein kinases. total protein preparations from different organs contain different kinase profiles, but all are within the range of 55 to 70 kd. at least four kinases are associated with highly purified plasma membranes from etiolated zucchini hypocotyls. the major phosphorylated polypeptides from plasma membranes range in ...199312231949
[main carotenoids in pressed seeds (cucurbitae semen) of oil pumpkin (cucurbita pepo convar. pepo var. styriaca)].various use of the oil-pumpkin offers reason for the phytochemical analysis of seed-meal's carotene pigments. column chromatography was performed on the adsorbents mgo, celite and caco3 with hexane and benzene as eluents. hplc separation of different pigments was carried out on a 6 microns reverse phase packing with a ternary gradient elution method using a diode-array detector. the main components of the press-residue were lutein [3,3'-dihydroxy-alpha-carotene = (3r,3'r,6'r)-beta,epsilon-carote ...19938249609
the effects of calcium deficiency on cucurbita pepo l. hypocotyl cells: a (31)p nuclear-magnetic-resonance study.calcium deficiency in zucchini (cucurbita pepo l.) is associated with reduced growth and a reduced ability to transport auxin (allan and rubery, 1991, planta 183, 604-612). an investigation of the effects of calcium-deficiency on zucchini hypocotyl cells was made using weak-acid uptake and (31)p-nuclear-magneticresonance ((31)p-nmr) spectroscopy in vivo and in tissue extracts. calcium-deficient tissue had the same cytoplasmic and vacuolar phs as normal tissue when extracellular ph was near neutr ...199324178486
vapor heat treatment for zucchini infested with bactrocera cucumis (diptera: tephritidae).zucchini, cucurbita pepo l., infested with 22-h-old eggs of bactrocera cucumis (french) were completely disinfested using a vapor heat treatment of 45 degrees c with > 94% rh for 30 min. an estimated total of 178,219 eggs (22 h old) was treated without survivors, thus achieving probit 9 mortality. twenty-two-h-old eggs were significantly more tolerant of heat than first, second, or third instars. all treatments were done in a sanshu model ehk-1000b vapor heat treatment system.19938432953
characterization of auxin-binding proteins from zucchini plasma membrane.we have previously identified two auxin-binding polypeptides in plasma membrane (pm) preparations from zucchini (cucurbita pepo l.) (hicks et al. 1989, proc. natl. acad. sci. usa 86, 4948-4952). these polypeptides have molecular weights of 40 kda and 42 kda and label specifically with the photoaffinity auxin analog 5-n3-7-3h-iaa (azido-iaa). azido-iaa permits both the covalent and radioactive tagging of auxin-binding proteins and has allowed us to characterize further the 40-kda and 42-kda polyp ...199311536546
slow degradation of the d1 protein is related to the susceptibility of low-light-grown pumpkin plants to photoinhibition.photoinhibition of photosystem ii (psii) electron transport and subsequent degradation of the d1 protein were studied in pumpkin (cucurbita pepo l.) leaves developed under high (1000 mumol m(-2) s(-1)) and low (80 mumol m(-2) s(-1)) photon flux densities. the low-light leaves were more susceptible to high light. this difference was greatly diminished when illumination was performed in the presence of chloramphenicol, indicating that a poor capacity to repair photodamaged psii centers is decisive ...199216653122
localization of galactinol, raffinose, and stachyose synthesis in cucurbita pepo leaves.the biochemical pathway of stachyose synthesis was localized by immunocytochemical and (14)c-labeling techniques in mature cucurbita pepo l. leaves. galactinol synthase (gas; ec 2.4.1.123), the first unique enzyme in this pathway, was immunolocalized within the intermediary cells of minor veins in conventionally fixed and cryo-fixed, resin-embedded sections using polyclonal anti-gas antibodies and protein a-gold. intermediary cells are specialized companion cells with extensive symplastic connec ...199224178325
phytotropin-binding sites and auxin transport in cucurbita pepo: evidence for two recognition sites.two properties of phytotropins, their ability to bind to 1-n-naphthylphthalamic acid (npa) receptors located on microsomal vesicles isolated from cucurbita pepo l. hypocotyls, and to stimulate auxin (indol-3-yl acetic acid, iaa) accumulation into such vesicles by blocking its efflux from them, were assessed in double labelling experiments using [2,3,4,5-(3)h]1-n-naphthylphthalamic acid and 3-indolyl-[2-(14)c]acetic acid. two sites of differing affinities and activities on iaa accumulation were f ...199224178053
flavonoids and flavonoid sulphates as probes of auxin-transport regulation in cucurbita pepo hypocotyl segments and vesicles.the accumulation of iaa by sealed microsomal vesicles prepared from hypocotyls of dark-grown cucurbita pepo l. (zucchini) seedlings was stimulated by n-1-naphthylphthalamic acid (npa: an inhibitor of carrier-mediated auxin efflux and hence of polar auxin transport) as well as by quercetin and certain other flavonoids with a specificity pattern similar to that previously shown for their npa-like effects on auxin transport and inhibition of npa binding to saturable sites. in contrast, putatively n ...199224186794
proton-transport activity, sidedness, and morphometry of tonoplast and plasma-membrane vesicles purified by free-flow electrophoresis from roots of lepidium sativum l. and hypocotyls of cucurbita pepo l.large-scale preparations of highly purified tonoplast and plasma-membrane vesicles were obtained from roots (garden cress, lepidium sativum l.) and shoots (etiolated zucchini hypocotyl, cucurbita pepo l.) of representative dicotyledonous seedlings. when tonoplast-enriched fractions of cress roots were prepared by centrifugation and then subjected to free-flow electrophoresis a highly purified tonoplast fraction was obtained. this fraction from cress roots was characterized by morphometry of fili ...199224186777
operation of the xanthophyll cycle in higher plants in response to diurnal changes in incident sunlight.changes in the carotenoid composition of leaves in response to diurnal changes in sunlight were determined in the crop species helianthus annuus l. (sunflower), cucurbita pepo l. (pumpkin), and cucumls sativus l. (cucumber), in the diaheliotropic mesophyte malva neglecta wallr., and in the perennial shrub euonymus kiautschovicus loesner. large daily changes were observed in the relative proportions of the components of the xanthophyll cycle, violaxanthin (v), antheraxanthin (a), and zeaxanthin ( ...199224186736
subthreshold changes in excitable membranes of cucurbits pepo l. stem cells during cooling-induced action-potential generation.the nature of subthreshold changes in excitable plasma membranes has been investigated in stem parenchyma cells of cucurbita pepo l. during action-potential generation induced by gradual cooling (from 23 to 10 ° c). the character of the subthreshold depolarization of excitable cells is shown to be mainly defined by a decrease in the activity of the plasma-membrane electrogenie pump (h(+)-atpase). in its turn, the pump activity is controlled by thermal changes in the structure of the membrane lip ...199224186654
small light-harvesting antenna does not protect from photoinhibition.high-light-induced decrease in photosystem ii (psii) electron transfer activity was studied in high- and low-light-grown pumpkin (cucurbita pepo l.) plants in vivo and in vitro. the psii light-harvesting antenna of the low-light leaves was estimated to be twice as big as that of the high-light leaves. the low-light leaves were more susceptible to photoinhibition in vivo. however, thylakoids isolated from these two plant materials were equally sensitive to photoinhibition when illuminated in the ...199116668423
stimulation by auxin of phospholipase a in membrane vesicles from an auxin-sensitive tissue is mediated by an auxin receptor.microsomal vesicles were prepared from zucchini (cucurbita pepo l.) hypocotyls containing radioactive phosphatidylethanolamine or phosphatidylcholine, and these lipids were used as substrates by phospholipase a which is activated by auxins. phospholipase d and phospholipase c hydrolysed the same substrates but were not influenced by auxin. phospholipase a was activated by the auxins indolyl-3-acetic acid, 2,4-dichlorophenoxyacetic acid and, to a lesser extent, by α-naphthaleneacetic acid whereas ...199124186343
two genes encoding 1-aminocyclopropane-1-carboxylate synthase in zucchini (cucurbita pepo) are clustered and similar but differentially regulated.a 17-kilobase (kb) region of the zucchini (cucurbita pepo) genome has been sequenced and contains two genes, cp-acc1a and cp-acc1b, encoding 1-aminocyclopropane-1-carboxylate synthase (acc synthase; s-adenosyl-l-methionine methylthioadenosine-lyase, ec 4.4.1.14). the genes are transcribed convergently and are separated by a 5.7-kb intergenic region. their coding regions are interrupted by four introns located in identical positions. while the dna identity in their coding regions is 97%, their 5' ...19911871117
purification and characterization of galactinol synthase from mature zucchini squash leaves.galactinol synthase catalyzes the first committed step in the biosynthesis of raffinose sugars. previous attempts to purify the enzyme have proven difficult and have resulted in low quantities of unpurified enzyme. galactinol synthase was purified 752-fold from mature zucchini (cucurbita pepo l. cv burpee hybrid) leaves using sequential liquid chromatography on de 52, octyl-sepharose cl-4b, and sephacryl s-200. this isolation scheme resulted in an 18.6% recovery of the initial activity. the puri ...199116668244
in vitro effects of monoterpenes on chloroplast membranes.a chloroplast preparation was extracted from squash (cucurbita pepo (l.) var. senator). enrichment of intact chloroplasts was achieved by continuous free-flow electrophoresis. the addition of monoterpenes, detergent and free fatty acids changed the elecrophoretic separation pattern characteristically. monoterpene-dependent degradation of envelope membranes could be prevented by addition of α-tocopherol prior to monoterpene incubation.photosynthetic electron transport of photosystem ii was comple ...199124414970
expression of ascorbic acid oxidase in zucchini squash (cucurbita pepo l.).the expression of ascorbic acid oxidase was studied in zucchini squash (cucurbita pepo l.), one of the most abundant natural sources of the enzyme. in the developing fruit, specific activity of ascorbic acid oxidase was highest between 4 and 6 days after anthesis. protein and mrna levels followed the same trend as enzyme activity. highest growth rate of the fruit occurred before 6 days after anthesis. within a given fruit, ascorbic acid oxidase activity and mrna level were highest in the epiderm ...199116668145
plant development in long-term embryogenic callus lines of cucurbita pepo.embryogenic callus derived from pumpkin hypocotyl segments was induced and maintained for 15 years on ms medium supplemented with the auxins iba (4.9 μm), 2, 4-d (4.5 μm) or iaa (5.7 μm). on induction media continued embryo maturation and development of adult plants typically failed. therefore, small embryogenic clumps and individually isolated embryos were subcultured two to four times on one of the conversion media: ms supplemented with 1.5% sucrose and (a) no hormone, (b) 2.9 μm iaa, (c) 5.7 ...199124213663
somatic embryogenesis and plant regeneration of squash cucurbita pepo l cv. yc 60.plant regeneration from tissue cultures of summer squash, cucurbita pepo l., cv. yc60, has been observed. somatic embryos organized from shoot apex derived callus cultured on murashige and skoog (ms) medium supplemented with 1.2 mg/l 2,4,5-trichlorophenoxyacetic acid, 0.8 mg/l benzylaminopurine, and 0.1 mg/l kinetin. embryos developed into plantlets by transfer of immature somatic embryos to ms medium with 0.05 mg/l naa and 0.05 mg/l kinetin. regenerated plants appeared morphologically normal an ...199124213662
calcium deficiency and auxin transport in cucurbita pepo l. seedlings.hypocotyls of cucurbita pepo l. (zucchini) seedlings grown at low calcium levels (0.1 mm) showed reduced basipetal polar transport of the auxins indole-3-acetic acid and 1-naphthylacetic acid in comparison with control plants grown at 5 mm ca(2+). the contribution to overall transmembrane auxin transport of the symport uptake carrier was unchanged by calcium deficiency, but the efflux carrier of the auxin-anion uniport was less active and the sensitivity of auxin transport to n-1-naphthylphthala ...199124193855
phytochrome-mediated detection of changes in reflected light.measurements of phytochrome photoequilibria and photoconversion rates in vivo, in seedlings of cucurbita pepo l. exposed to light in growth chambers, indicate that significant changes in the state of phytochrome can be brought about by changes in the quality and quantity of the light reflected from the walls of the growth chambers. the changes in reflected light, although large, were small in terms of the total radiation (direct light from the lamps plus wall-reflected light) to which the seedli ...199116667942
treatment of benign prostatic hyperplasia with phytosterols.in a randomised, double-blind study, the preparation curbicin, obtained from pumpkin seeds and dwarf palm plants (cucurbita pepo l. and sabal serrulata), was compared with a placebo in the treatment of symptoms caused by prostatic hyperplasia; 53 patients took part in the study, which was carried out over a 3-month period. urinary flow, micturition time, residual urine, frequency of micturition and a subjective assessment of the effect of treatment were all significantly improved in the treatmen ...19901702340
temperature-dependent changes in photosystem ii heterogeneity support a cycle of photosystem ii during photoinhibition.high light treatments were given to attached leaves of pumpkin (cucurbita pepo l.) at room temperature and at 1°c where the diffusion- and enzyme-dependent repair processes of photosystem ii are at a minimum. after treatments, electron transfer activities and fluorescence induction were measured from thylakoids isolated from the treated leaves. when the photoinhibition treatment was given at 1°c, the photosystem ii electron transfer assays that were designed to require electron transfer to the p ...199024420463
temperature-dependent changes in photosystem ii heterogeneity of attached leaves under high light.attached leaves of pumpkin (cucurbita pepo l. cv. jattiläismeloni) were exposed to high light intensity at room temperature (ca 23°c) and at 1°c. fluorescence parameters and electron transport activities measured from isolated thylakoids indicated faster photoinhibition of psii at low temperature. separation of the α and β components of the complementary area above the fluorescence induction curve of dichlorophenyl-dimethylurea-poisoned thylakoids revealed that at low temperature only the α-cent ...199021087264
distribution of chlorophyll-protein complexes during chilling in the light compared with heat-induced modifications.the effects of chilling in the light (4 days at 5 degrees c and 100-200 micromoles of photons per square meter per second) on the distribution of chlorophyll (chl) protein complexes between appressed and nonappressed thylakoid regions of pumpkin (cucurbita pepo l.) chloroplasts were studied and compared with the changes occurring during in vitro heat treatment (5 minutes at 40 degrees c) of isolated thylakoids. both treatments induced an increase (18 and 65%, respectively) in the relative amount ...199016667464
kinetic features of ascorbic acid oxidase after partial deglycation.by means of specific exoglycosidases, sugars have been removed under non-denaturing conditions from ascorbic acid oxidase (aao), different deglycation schedules being followed. our results indicate that deglycation clearly affects the kinetic features of aao, leading to an increase of 'affinity' and 'catalytic ability' of the enzymic forms so generated. a better exposure of the catalytic-site residues could be supposed to occur upon treatment with exoglycosidases. this is supported by the three- ...19892604732
the nature of light-induced inhibition of photosystem ii in pumpkin (cucurbita pepo l.) leaves depends on temperature.attached leaves of pumpkin (cucurbita pepo l.) were treated in high or moderate light at room temperature or a 1 degrees c. the symptoms of photoinhibition appearing during light treatments at room temperature could be attributed to a decrease in the primary activity of psii. however, when the light treatment was given at 1 degrees c, the quantum yield of photosynthetic oxygen evolution decreased much more than would be expected from the decrease in the ratio of variable to maximum fluorescence ...198916667113
phospholipid-stimulated protein kinase in plants.in membrane fractions from zucchini (cucurbita pepo l.) hypocotyls, catalytic properties of a platelet-activating factor (paf)-activated protein kinase were investigated. in the presence of [ethylenebis(oxyethylenenitrilo)]tetraacetic acid, phosphorylation of a 55-kda membrane polypeptide and, to a lesser extent, several others, including a 120-kda polypeptide, was stimulated by paf. the phosphorylation of the 55-kda polypeptide was used for quantification of the paf-stimulated protein kinase. s ...19892530218
viability of cururbita pepo pollen: biophysical and structural data.during ageing of the short-lived pollen grains of cucurbita pepo l., water loss was examined in relation to viability using biophysical ((1)h-nuclear magnetic resonance, nmr) and cytological methods (fluorochromatic reaction test, freezefracture and scanning electron microscopy). a semi-logarithmic representation of the pollen weight loss demonstrated the complexity of the dehydration process. a the study of proton loss using (1)h-nmr indicated that two major releases water of had taken place, e ...198924201515
a rapid response to a plant hormone: auxin stimulates phospholipase a2 in vivo and in vitro.addition of the active auxins indole-3-acetic acid, 2,4-dichlorophenoxyacetic acid or alpha-naphthylacetic acid to cultured soybean (glycine max l.) cells prelabeled with ethanolamine or choline increased the radioactivity in the lysophosphatidylethanolamine (lpe) or lysophosphatidylcholine (lpc) pool within 5 min. the inactive auxin analogue, beta-naphthylacetic acid, was inactive in this response. in membranes prelabeled in vivo, either with ethanolamine or choline, and subsequently isolated f ...19892775252
symplastic continuity between mesophyll and companion cells in minor veins of mature cucurbita pepo l. leaves.dye-coupling studies have been undertaken to determine whether plasmodesmata between intermediary cells (companion cells) and bundle-sheath cells in the minor veins of mature cucurbita pepo l. leaves are open to passage of low-molecular-weight compounds. the abaxial phloem of these veins was exposed by stripping the lower epidermis of the leaf and removing the spongy-mesophyll cells by abrasion. lucifer yellow, or 6-carboxyfluorescein, were microinjected into intermediary cells by iontophoresis, ...198924201418
specific photoaffinity labeling of two plasma membrane polypeptides with an azido auxin.plasma membrane vesicles were isolated from zucchini (cucurbita pepo) hypocotyl tissue by aqueous phase partitioning and assessed for homogeneity by the use of membrane-specific enzyme assays. the highly pure (ca. 95%) plasma membrane vesicles maintained a ph differential across the membrane and accumulated a tritiated azido analogue of 3-indoleacetic acid (iaa), 5-azido-[7-3h]iaa ([3h]n3iaa), in a manner similar to the accumulation of [3h]iaa. the association of the [3h]n3iaa with membrane vesi ...198911537412
red light-induced accumulation of ubiquitin-phytochrome conjugates in both monocots and dicots.phytochrome is rapidly degraded in vivo after photoconversion from the stable red-absorbing (pr) form to the far red-absorbing (pfr) form. previously, we have shown in etiolated oat seedlings that ubiquitin-phytochrome conjugates (ub-p) appear after pfr formation suggesting that oat phytochrome is rapidly degraded by a ubiquitin-dependent proteolytic pathway. here, we extend this observation to etiolated tissue from other monocotyledonous (corn [zea mays. (l.)] and rye [secale cereale (l.)] and ...198916666778
heterogeneity of auxin-accumulating membrane vesicles from cucurbita and zea: a possible reflection of cell polarity.when microsomes from hypocotyls of cucurbita pepo l. or coleoptiles of zea mays l. were centrifuged on dextran-sucrose gradients a heterogeneity of auxin-accumulating vesicles was observed. vesicles from the top part of the gradient showed saturable, specific accumulation of indole-3-acetic acid with only a small stimulation by phytotropins, and with very few binding sites for 1-n-naphthylphthalamic acid. in the vesicles from the lower part of the gradient, net accumulation of indole-3-acetic ac ...198924212422
gtp causes calcium release from a plant microsomal fraction.studies on a variety of animal cell types have revealed a gtp-specific calcium-releasing mechanism in a non-mitochondrial, microsomal fraction. here we report that gtp also induces rapid release of calcium from a zucchini (cucurbita pepo l.) hypocotyl microsomal fraction. maximal release occurs at 50 microm, and half-maximal release at 8 microm gtp. gtp is highly specific in its effect, and may not be replaced by utp, atp, ctp, ttp, gmp, or by non-hydrolysable analogues of gtp. reuptake of calci ...19892701802
bisulfite interacts with binding sites of the auxin-transport inhibitor n-1-naphthylphthalamic acid.the affinity of the auxin-transport inhibitor n-1-naphthylphthalamic acid (npa) for membrane particles as well as for solubilized binding sites from cucurbita pepo l. hypocotyls was reduced by low concentrations of bisulfite (half-maximal inhibition at 2·10(-3)-3·10(-3) m). two membrane fractions obtained by sedimentation aided with polyethylene glycol showed differential sensitivity to bisulfite. other oxidizing or reducing substances tested at 1 mm had no effect, except for n-ethylmaleimide (8 ...198824220862
import of peroxisomal hydroxypyruvate reductase into glyoxysomes.a new procedure was used to purify the peroxisomal matrix enzyme hydroxypyruvate reductase (hpr) from green leaves of pumpkin (cucurbita pepo l.) and spinach (spinacia oleracea l.). monospecific antibodies were prepared against this enzyme in rabbits. immunoprecipitation of hpr from watermelon (citrullus vulgaris schrad.) yielded a single protein with a subunit molecular weight of 45 kda. immunohistochemical labeling of hpr was found exclusively in watermelon microbodies. isolated polyadenylated ...198824220768
amino acid transport into membrane vesicles isolated from zucchini : evidence of a proton-amino acid symport in the plasmalemma.several lines of evidence with intact tissues suggest amino acid transport is mediated by a proton-amino acid symport (l rheinhold, a kaplan 1984 annu rev plant physiol 35: 45-83). however, biochemical studies of proton-coupled amino acid transport in isolated membrane vesicles have not been reported. in the experiments presented here, amino acid transport was studied in membrane vesicles isolated from zucchini (cucurbita pepo l. cv black beauty) hypocotyls. an imposed ph gradient (basic interio ...198816666332
rearrangement of the chloroplast thylakoid at chilling temperature in the light.the leaves of chilling-sensitive pumpkin (cucurbita pepo l.) showed symptoms reminiscent of photoinhibition when kept for 4 days at 5 degrees c in moderate light. a decrease was observed in the variable part of chlorophyll alpha fluorescence, apparent quantum yield, and maximum rate of o(2) evolution. chloroplast whole-chain electron transport activity measured from chloroplast thylakoids had decreased to 51% of the control value. photosystem ii (psii) activity decreased by only 9%, suggesting t ...198816666221
azide-binding studies reveal type 3 copper heterogeneity in ascorbate oxidase from the green zucchini squash (cucurbita pepo).titration of native ascorbate oxidase from green zucchini squash (cucurbita pepo) with azide in 0.1 m-phosphate buffer, ph 6.8, exhibits a biphasic spectral behaviour. binding of the anion with 'high affinity' (k greater than 5000 m-1) produces a broad increase of absorption in the 400-500 nm region (delta epsilon approximately 1000 m-1.cm-1) and c.d. activity in the 300-450 nm region, whereas azide binding with 'low affinity' (k approximately 100 m-1) is characterized by an intense absorption b ...19882840893
an endogenous rna-synthesis-promoting oligopeptide from cucurbita pepto var. patissonina.the effect of cppti (cucurbita pepo patissonina trypsin inhibitor) on the growth of cucurbita pepo var patissonina (white bush) was examined. plants treated with cppti grew faster than untreated plants and similarly to those treated with gibberellic acid. isolated cell nuclei from plants treated with cppti showed that of the three dna-dependent rna polymerases assayed, rna polymerase i (ec2.7.7.6) activity was preferentially elevated.198824226178
cloning of cdna for phytochrome from etiolated cucurbita and coordinate photoregulation of the abundance of two distinct phytochrome transcripts.we have isolated several cdna clones for phytochrome from a dicot, cucurbita pepo l. cv. black beauty (zucchini), and have used them to study the regulation of cucurbita phytochrome mrna levels. a cdna library was constructed from poly(a)(+) rna isolated from etiolated cucurbita hypocotyl hooks and enriched for phytochrome mrna by size fractionation. this library was screened with a (32)p-labeled fragment isolated from an avena phytochrome cdna clone. several putative phytochrome clones were iso ...198724301311
solubilization and purification of nad(p)h dehydrogenase of cucurbita microsomes.an nad(p)h dehydrogenase stimulated by quinone (p pupillo, v valenti, l de luca, r hertel 1986 plant physiol 80: 384-389) was solubilized from washed microsomes of zucchini squash hypocotyls (cucurbita pepo l.) by use of 1% triton x-100. the solubilized enzyme remained in solution in aqueous buffer and could be purified by a combination of sepharose 6b chromatography and blue ultrogel chromatography. of the three peaks of activity eluted from the latter column with a salt gradient, peak 3 had 50 ...198716665785
genetics of resistance to red pumpkin beetle (a ulacophora foveicollis) in summer squash (cucurbita pepo l.).resistance to red pumpkin beetle in summer squash was found to be controlled by polygenes. diallel and triple test cross analysis revealed the preponderance of non-additive and additive gene effects for resistance respectively. absence of epistasis for resistance was indicated by both tests.198724241196
a plant lipid and the platelet-activating factor stimulate atp-dependent h(+) transport in isolated plant membrane vesicles.a plant lipid was isolated from zucchini (cucurbita pepo l.) membranes and from soybean (glycine max [l.] merr) phospholipids by thinlayer chromatography and further purified by high-performance liquid chromatography. this plant lipid was chromatographically very similar to the platelet-activating factor, an ether phospho-lipid with hormone-like properties found in mammals. both the plant lipid and the platelet-activating factor stimulated atp-dependent h(+) transport in isolated membrane vesicl ...198724225797
5'-azido-n-1-napthylphthalamic acid, a photolabile analog of n-1-naphthylphthalamic acid : synthesis and binding properties in curcurbita pepo l.a photolabile analog of n-1-naphthylphthalamic acid (npa), 5'-azido-n-1-naphthylphthalamic acid (az-npa), has been synthesized and characterized. this potential photoaffinity label for the plasma membrane npa binding protein competes with [(3)h]npa for binding sites on curcurbita pepo l. (zucchini) hypocotyl cell membranes with k(0.5) = 2.8 x 10(-7) molar. the k(0.5) for npa under these conditions is 2 x 10(-8) molar, indicating that the affinity of az-npa for the membranes is only 14-fold lower ...198716665662
auxin carriers in cucurbita vesicles : iii. specificity, with particular reference to 1-naphthylacetic acid.carrier-mediated uptake of indole-3-acetic acid (iaa) by microsomal vesicles from cucurbita pepo l. hypocotyls was strongly inhibited by 2,4-dichlorophenoxyacetic acid (2,4-d; i 50= 0.3 μm) but only weakly by 1-naphthylacetic acid (naa). the fully ionised auxin indol-3-yl methanesulphonic acid also inhibited (i 50=3 μm). the same affinity ranking of these auxins for the uptake carrier, an electroimpelled auxin anion-h(+) symport, is demonstrable in hypocotyl segments. the specificity of the auxi ...198724225714
auxin carriers in cucurbita vesicles : ii. evidence that carrier-mediated routes of both indole-3-acetic acid influx and efflux are electroimpelled.the association at 0° c of [(3)h]indole-3-acetic acid (iaa) with membrane vesicles prepared from cucurbita pepo l. hypocotyls at ph 7.9 and resuspended at ph 6.0 was greatly diminished by osmotic shrinkage. nonradioactive iaa inhibited a large proportion of this association thus revealing a saturable component, also decreased by osmotic shrinkage, which mainly represents operation of an auxin uptake carrier, with saturable binding having only a minor role. the contribution of this carrier to the ...198724225713
auxin carriers in cucurbita vesicles : i. imposed perturbations of transmembrane ph and electrical potential gradients characterised by radioactive probes.the behaviour of radioactive probes of transmembrane ph gradients ([(14)c]butyric acid) and electrical potential gradients ((86)rb(+) and s(14)cn(-)) has been characterised in membrane vesicles from cucurbita pepo l. hypocotyls subjected to changing gradients and ionophore-mediated changes in the conductivity of k(+) and h(+) ions. the vesicles are sealed in the presence of 25 mm kcl. the k(+) ionophore valinomycin changes the distribution of (86)rb(+) and of s(14)cn(-) in opposite directions, w ...198724225712
quality of a stress-sensitive cucurbita pepo l. pollen.the quality of cucurbita pepo l. pollen was studied using field pollinations and the fluorochromatic-reaction test. the extreme sensitivity of this pollen to dehydration and ageing is demonstrated. controlled stress applied to mature pollen leads to the development of seedless fruits. molecular signals seem to be involved in the induction of this parthenocarpy. these results indicate the existence of distinct sequences involved in the completion of the fertilization program of pollen. with polle ...198724227273
effect of cytokinins on ribosomal rna gene expression in excised cotyledons of cucurbita pepo l.excised pumpkin (cucurbita pepo l.) cotyledons were used to investigate the effects of two different types of cytokinins: n(6)-benzyladenine and n1-(2-chloro-4-pyridyl)-n2-phenylurea on rna synthesis in isolated nuclei. treatment of cotyledons with both cytokinins resulted in a rapid enhancement of nuclear rna-polymerase-i activity (ec 2.7.7.6). maximum stimulation of rna polymerase i, responsible for rrna synthesis, was observed 4-6 h after the start of cytokinin action. the activity of rna pol ...198724232967
metabolic requirement of cucurbita pepo for boron.lateral roots of intact summer squash seedlings (cucurbita pepo l.) were used to quantify the effects of boron deficiency on dna synthesis, protein synthesis, and respiration. the temporal relationship between changes in these metabolic activities and the cessation of root elongation caused by boron deprivation was determined. transferring 5-day-old squash seedlings to a hydroponic culture medium without boron for 6 hours resulted in a 62% reduction in net root elongation and a 30% decrease in t ...198716665231
pollen gene expression analysed by micro-isoelectric focusing of proteins from isolated pollen grains in cucurbita pepo l.isoelectric focusing of proteins from single pollen grains of cucurbita pepo l. has been developed for large scale study of pollen grain populations' heterogeneity. forty to forty-five protein bands from one pollen grain are revealed after silver staining. applications of this technique to pollen grain populations from different genotypes are described in this paper. possible applications and limits of this technique are discussed with respect to plant breeding especially for the measure of gene ...198624240746
evidence supporting a model of voltage-dependent uptake of auxin into cucurbita vesicles.the accumulation of [(14)c]indole-3-acetic acid (iaa), of [(3)h]tetra-phenyl phosphonium ion as a membrane potential probe, and of [(14)c]butyric acid as probe for ph gradients was studied with membrane vesicles from etiolated hypocotyls of cucurbita pepo. ion gradients (k(+), h(+)) were applied in the presence and absence of specific ionophores e.g. valinomycin or carbonylcyanide m-chlorophenylhydrazone. in all cases tested, the accumulation of [(14)c]iaa equals neither potential probe nor ph-p ...198624232555
calcium-binding and its effect on circular dichroism of plant calmodulin.the ca(2+)-binding properties of calmodulin purified from zucchini (cucurbita pepo l.) has been determined. a value of 3.3 mol ca(2+) per mol of zucchini calmodulin was measured at ph 7.5 by equilibrium chromatography. the far-and near-uv circular-dichroic spectra of the ca(2+)-and mg(2+)-saturated as well as from the metal-free forms of zucchini calmodulin reveal that upon ca(2+)-binding the α-helix content increases. a comparison with the spectra of vertebrate calmodulin indicates that both ca ...198524241435
active auxin uptake by zucchini membrane vesicles: quantitation using esr volume and delta ph determinations.closed and ph-tight membrane vesicles prepared from hypocotyls of 5-day-old dark-grown seedlings of cucurbita pepo accumulate the plant growth hormone indole-3-acetic acid along an imposed proton gradient (ph low outside, high inside). the use of electron paramagnetic spin probes permitted quantitation both of apparent vesicle volume and magnitude of the ph gradient. under the experimental conditions used, hormone accumulation was at minimum 20-fold, a value 4 times larger than what one would pr ...19852995970
release of ca2+ from plant hypocotyl microsomes by inositol-1,4,5-trisphosphate.the effect of inositol-1,4,5-trisphosphate on ca2+ release from microsomes isolated from dark-grown zucchini (cucurbita pepo l.) hypocotyls was studied. up to 30% of the ca2+ taken up by the microsomes in the presence of 2mm atp, was released by mumolar concentrations of inositol-1,4, 5-trisphosphate. this release was very rapid (less than 0.5 min) and was followed by a slower re-uptake of ca2+. the microsomal levels of ca2+ previously attained were not re-established within 5 min. external conc ...19853875346
cytokinin-modulated gene expression in excised pumpkin cotyledons.comparison of two-dimensional polyacrylamide gel electrophoretic maps of proteins isolated from benzyladenine-treated and untreated pumpkin (cucurbita pepo l. cv halloween) cotyledons showed that the expression of certain proteins is enhanced, induced, or suppressed by the cytokinin treatment. the amount of poly(a)(+) mrna isolated from cotyledons incubated with 10(-4) molar benzyladenine for five days was about four-fold over the water-incubated control. the activity of hydroxypyruvate reductas ...198516664037
genetic control of plastid carotenoids and transformation in the skin of cucurbita pepo l. fruit.the influence of allelic state of gene b on skin pigmentation in two cultivars of cucurbita pepo l. has been studied. total carotenoids were lower at early stages of fruit development in cultivar (cv.) 'early prolific' (ep) bb yy fruit skin, than in ep b (+) b (+) yy fruit skin, but no differences were observed in total skin carotenoids twenty days after anthesis. total carotenoids were lower in cv. 'fordhook zucchini' (fz) bb yy fruit skin, than in fz b (+) b (+) yy fruit skin at all developmen ...198424257820
a comparative study of carrier participation in the transport of 2,3,5-triiodobenzoic acid, indole-3-acetic acid, and 2,4-dichlorophenoxyacetic acid by cucurbita pepo l. hypocotyl segments.the transmembrane transport of indole-3-acetic acidd (iaa) and 2,4-dichlorophenoxyacetic acid (2,4-d) by 2 mm segments of dark-grown cucurbita pepo l. hypocotyls involves nonme-diated diffusion of the neutral protonated auxin species as well as carrier-mediated components for influx and efflux. the efflux carrier is blocked by 2,3,5-triiodobenzoic acid (tiba), a noncompetitive inhibitor of polar auxin transport which is itself transported in a polar fashion. the transmembrane transport of tiba i ...198423194793
aspartate carbamyltransferase : site of end-product inhibition of the orotate pathway in intact cells of cucurbita pepo.lovatt et al. (1979 plant physiol 64: 562-569) have previously demonstrated that end-product inhibition functions as a mechanism regulating the activity of the orotic acid pathway in intact cells of roots excised from 2-day-old squash plants (cucurbita pepo l. cv early prolific straightneck). uridine (0.5 millimolar final concentration) or one of its metabolites inhibited the incorporation of nah(14)co(3), but not [(14)c]carbamylaspartate or [(14)c]orotic acid, into uridine nucleotides (sigmaump ...198416663656
the involvement of endogenous cytokinin-like and gibberellin-like substances in germination and early seedling growth of cucurbita pepo l.mature dry seeds of cucurbita pepo contained measurable quantities of both gibberellin-like and cytokinin-like materials. during germination, levels of endogenous gibberellin-like substances initially fell, but subsequently increased again. at no time, however, was there more endogenous gibberellin activity present than in the dry seeds. in terms of the amounts of gibberellin reported in other tissues, the levels in these seeds were low. most of the cytokinin-like activity present was in the for ...198423195299
trypsin inhibitors in summer squash (cucurbita pepo) seeds. isolation, purification and partial characterization of three inhibitors.three trypsin inhibitors were isolated from summer squash (cucurbita pepo) seeds and purified to homogeneity by fractionation with ammonium sulphate and methanol, ion-exchange chromatography and gel filtration. all three inhibitors have lysine at their active site. two of them (ii, iv) show the same isoelectric point (at ph 5.6), amino acid composition and molecular mass (3259). the third inhibitor (iii) of molecular mass of 3654 and isoelectric point at 4.9 has additionally one histidine residu ...19846524213
de novo purine biosynthesis in intact cells of cucurbita pepo.the capacity of intact cells of roots excised from summer squash plants (cucurbita pepo l. cv early prolific straightneck) to synthesize purine nucleotides de novo was investigated. evidence that purine nucleotides are synthesized de novo included: (a) demonstration of the incorporation of [1-(14)c]glycine, [2-(14)c]glycine, nah(14)co(3), and h(14)coona into total adenine nucleotides; (b) observation that the addition of azaserine or aminopterin, known inhibitors of de novo purine synthesis in o ...198316663298
role of o-acetylserine in hydrogen sulfide emission from pumpkin leaves in response to sulfate.in the presence of excess sulfate, cysteine synthesis in pumpkin (cucurbita pepo) leaves is not limited by sulfate reduction, but by the availability of o-acetylserine. feeding of o-acetylserine or its metabolic precursors s-acetyl-coenzyme-a and coenzyme a to leaf discs enhanced the incorportion of [(35)s]sulfate into reduced sulfur compounds, mainly into cysteine, at the cost of lowered h(2)s emission; the uptake and reduction of sulfate is not affected by these treatments. beta-fluoropyruvate ...198316663258
protein phosphorylation and its regulation by calcium and calmodulin in membrane fractions from zucchini hypocotyls.protein-kinase activity has been found to be associated with a membrane fraction obtained from dark-grown zucchini (cucurbita pepo l., cv. senator) hypocotyl hooks. proteins of this membrane fraction were used as protein substrates. the effects of mg(2+), na(+) and k(+) on phosphorylation, measured as (32)p incorporation, was investigated. the kinetics of phosphorylation of the individual protein peptides indicate the presence of specific phosphatase activity. phosphorylation activity is strongl ...198324264929
heterogeneity of pumpkin ribosomal dna.the ribosomal dna (rdna) of cucurbita pepo l. has been found to consist of tandemly arrayed repeat units, most of which are 10 kilobases in length. thirty-six repeat units, cloned into the hindiii site of pacyc 177, fall into seven classes which differ from each other in length and/or nucleotide sequence. most of the heterogeneity occurs in noncoding portions of the repeat unit although there is some nucleotide sequence variation in the coding portion as well. heterogeneity of base modification ...198316662953
auxin transport in membrane vesicles from cucurbita pepo l.association of (14)c-labelled indole-3-acetic acid (iaa) with membrane particles from zucchini (cucurbita pepo l.) hypocotyls - previously described as "site iii binding" (m. jacobs and r. hertel, 1978, planta 142, 1-10) - is reinterpreted as a carrier-mediated uptake into closed and sealed vesicles driven by a ph gradient. accumulation of the radioactive auxin is saturable, sensitive to the protonophore, carbonyl cyanide p-trifluoromethoxyphenyl hydrazone (fccp), and to nigericin, and requires ...198324264147
partial purification and properties of an alkaline alpha-galactosidase from mature leaves of cucurbita pepo.a fourth molecular from of alpha-galactosidase, designated l(iv), an alkaline alpha-galactosidase, was isolated from leaves of cucurbita pepo and purified 165-fold. it was active over a narrow ph range with optimal hydrolysis of p-nitrophenyl-alpha-d-galactoside and stachyose at ph 7.5. the rate of stachyose hydrolysis was 10 times that of raffinose. k(m) determinations in mcilvaine buffer (200 millimolar na(2)-phosphate, 100 millimolar citric acid, ph 7.5) for p-nitrophenyl-alpha-d-galactoside, ...198316662884
a reinvestigation on the quaternary structure of ascorbate oxidase from cucurbita pepo medullosa.the optical properties, copper content, catalytic activity and quaternary structure of many preparations of ascorbate oxidase purified with two different methods were examined. fresh samples appeared identical and were characterized by optical ratios a280/a610 = 25 +/- 1 and a330/a610 = 0.8 +/- 0.05, by specific activity toward ascorbate of 3.48 +/- 0.05 mol g-1 min-1 and by a copper content of 8 +/- 0.3 mol/145 000 mr. the enzyme is composed of two non-covalently linked subunits of slightly dif ...19836646110
peptide hydrolase activities in seedlings and hormone-treated cotyledons of pumpkin (cucurbita pepo).enzymes hydrolyzing gly-ala-, met-met- and pro-4-phenylazo-phenylamides, and n-benzoyl-l-arginine-4-nitroanilide have been identified in germinating seeds and cotyledons of pumpkin (cucurbita pepo). the enzyme activities per cotyledon increase markedly during the germination process, but the proportion of enhancement depends on the type of enzyme species. the increase in enzyme activities is due to de novo synthesis as shown by cycloheximide treatment and is influenced by phytohormones (cytokini ...19836360167
kinetics of leaf nitrite reductase with methyl viologen and ferredoxin under controlled redox conditions.some factors that influence the activity of nitrite reductase (ec 1.7.7.1) were investigated, the enzyme from curcurbita pepo (vegetable marrow) being used. the activity with ferredoxin or methyl viologen as electron donor was inhibited by certain salts, including nacl. the steady-state kinetic parameters measured in a commonly used open-tube (aerobic) system were compared with a closed-cell (anaerobic) system in which the redox potential, and thus the concentrations of oxidized and reduced dono ...19827126179
superoxide, hydrogen peroxide, and the gelling of phloem sap from cucurbita pepo.the possible involvement of superoxide and hydrogen peroxide in the oxidative gelling of phloem exudate from cucurbita pepo. was investigated. neither superoxide dismutase (ec 1.15.1.1) nor catalase (ec 1.11.1.6) inhibited the reaction. although catalase could not be detected in exudate, both peroxidase (ec. 1.11.1.7) and superoxide dismutase were present in reasonable amounts. polyacrylamide gel electrophoresis revealed one major and one minor isozyme of superoxide dismutase, both of which were ...198224276155
stimulation of h(2)s emission from pumpkin leaves by inhibition of glutathione synthesis.the effect of inhibitors of glutathione (gsh) synthesis, namely gamma-methyl glutamic acid, d-glutamic acid, cystamine, methionine-s-sulfoximine (msx), buthionine-s-sulfoximine, and gsh itself, on the emission of h(2)s was investigated. all these compounds stimulated h(2)s emission from pumpkin (cucurbita pepo l. cv small sugar pumpkin) leaf discs in response to sulfate. msx and gsh were the most effective compounds, stimulating h(2)s emission from leaf discs of mature pumpkin leaves by about 80 ...198216662293
use of triton wr-1339 in cytochemical and biochemical characterization of phytolysosomes.a new cytochemical assay of acid phosphatase activity employing triton wr-1339, a non-ionic detergent, has been used to demonstrate the probable origin of the phytolysosome system and of the organization of the golgi complex in the root meristem, cucurbita pepo. the results were controlled biochemically by differential and linear density gradient ultracentrifugation of extracts from normal and triton-treated roots. the various fractions were characterized by electron microscopy or by assay of ma ...19826284682
partitioning yield loss on yellow squash into nematode and insect components.the effect of a contplex of several insect and nematode pests on yield of yellow squash (cucurbita pepo l.) was examined in two field tests in southern florida. applications of permethrin for insect control and oxamyl primarily for nematode control plus some insect control were made alone and in combination to achieve differential reduction of various insect and nematode components contributing to yield loss. the effect of these components on yield was further analyzed by multiple regression. yi ...198219295683
synthesis, salvage, and catabolism of uridine nucleotides in boron-deficient squash roots.previous work has provided evidence that plants may require boron to maintain adequate levels of pyrimidine nucleotides, suggesting that the state of boron deficiency may actually be one of pyrimidine starvation. since the availability of pyrimidine nucleotides is influenced by their rates of synthesis, salvage, and catabolism, we compared these activities in the terminal 3 centimeters of roots excised from boron-deficient and -sufficient squash plants (cucurbita pepo l.). transferring 5-day-old ...198116662114
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