Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| p nmr observations on the effect of the external ph on the intracellular ph values in plant cell suspension cultures. | (31)p nuclear magnetic resonance (nmr) spectroscopy was used to monitor the response of oil palm (elaeis guineensis) and carrot (daucus carota) cell suspensions to changes in the external ph. an airlift system was used to oxygenate the cells during the nmr measurements and a protocol was developed to enable a constant external ph to be maintained in the suspension when required. phosphonoacetic acid was used as an external ph marker and the intracellular ph values were measured from the chemical ... | 1990 | 16667496 |
| purification and characterization of aspartate aminotransferase isoenzymes from carrot suspension cultures. | three aspartate aminotransferase isoenzymes were identified from extracts of carrot (daucus carota l.) cell suspension cultures. these isoenzymes were separated by deae chromatography and were analyzed on native gradient polyacrylamide gels. the relative molecular weights of the isoenzymes were 111,000 +/- 5000, 105,000 +/- 5000, and 94,000 +/- 4000 daltons; they were designated forms i, ii, and iii, respectively. form i, the predominant form, has been purified to apparent homogeneity (>300-fold ... | 1990 | 16667320 |
| immunological characterization of in vitro forms of homoserine dehydrogenase from carrot suspension cultures. | multiple forms of homoserine dehydrogenase (hsdh) from carrot (daucus carota l.) have been identified. one form of hsdh (t-form) has a relative molecular weight of 240,000 and is strongly inhibited by threonine. another form (k-form) has a relative molecular weight of 180,000 and is insensitive to inhibition by threonine. the interconversion of these two forms is dependent upon the presence or absence of threonine and potassium. polyacrylamide electrophoretic gels stained for hsdh activity and p ... | 1990 | 16667288 |
| purification and interconversion of homoserine dehydrogenase from daucus carota cell suspension cultures. | homoserine dehydrogenase from cell suspension cultures of carrot (daucus carota l.) has been purified to apparent homogeneity by a combination of selective heat denaturation, ion exchange and gel filtration chromatographies, and preparative gel electrophoresis. carrot homoserine dehydrogenase is composed of subunits of equal molecular weight (85,000 +/- 5,000). during purification, the enzyme exists predominantly in two molecular weight forms, 180,000 and 240,000. the enzyme can be reversibly co ... | 1989 | 16667218 |
| coregulation of dihydrofolate reductase and thymidylate synthase in overproducer cell lines of wild carrot. | dihydrofolate reductase (dhfr) and thymidylate synthase (ts) activities are associated with a 285,000 molecular weight enzyme complex in carrot (daucus carota l.). selection for methotrexate (mtx) resistance by stepwise increase of the concentration of mtx results in a high frequency adaptation to mtx with little or no significant increase in dhfr activity. however, when as a second step following mtx selection a specific inhibitor of ts, 5-fluoro-2-deoxyuridine was used, dhfr overproducer lines ... | 1989 | 16667128 |
| ethylene-like activity of isocyanides. | benzyl isocyanide, cyclohexyl isocyanide, benzyl isocyanate, methyl isocyanate, benzyl isothiocyanate, and methyl isothiocyanate were each tested for ethylene-like activity in a pea (pisum sativum) growth assay. only the isocyanides gave an ethylene-like response; the concentration that gave a half-maximal response was approximately 10 to 15 microliters per liter for each isocyanide, and this activity was inhibited by norbornadiene, a competitive inhibitor of ethylene action. since the isocyanid ... | 1989 | 16667085 |
| the heat shock response of carrot : protein variations between cultured cell lines. | we have defined several parameters surrounding the heat shock response of cultured cells of carrot (daucus carota l.) and have found that these cells exhibit a typical "higher plant" heat shock response. in particular, the resolution of the heat shock proteins (hsps) by two-dimensional polyacrylamide gel electrophoresis (page) has revealed a pattern of proteins very similar to the hsps from soybean; specifically, the low molecular weight class is composed of approximately 15 to 20 different poly ... | 1989 | 16667068 |
| inositol trisphosphate metabolism in carrot (daucus carota l.) cells. | the metabolism of exogenously added d-myo-[1-(3)h]inositol 1,4,5-trisphosphate (ip(3)) has been examined in microsomal membrane and soluble fractions of carrot (daucus carota l.) cells grown in suspension culture. when [(3)h]ip(3) was added to a microsomal membrane fraction, [(3)h]ip(2) was the primary metabolite consisting of approximately 83% of the total recovered [(3)h] by paper electrophoresis. [(3)h]ip was only 6% of the [(3)h] recovered, and 10% of the [(3)h]ip(3) was not further metaboli ... | 1989 | 16667056 |
| interruption of somatic embryogenesis in daucus carota l. by 5-bromodeoxyuridine. | embryogenic daucus carota l. cells grown in 9 micromolar 2.4-dichlorophenoxyacetic acid are resistant to greater than 5 micromolar 5-bromodeoxyuridine (brdu). in contrast, 5 micromolar brdu strongly inhibits somatic embryogenesis within 24 hours after transfer of cells to an auxin-free medium. dna synthesis rates in control and brdu-treated cultures are rapid and similar; however, the dna content does not reach levels as great in the presence of brdu as in control cultures. brdu substitutes for ... | 1989 | 16666898 |
| characterization of a xylose-specific antiserum that reacts with the complex asparagine-linked glycans of extracellular and vacuolar glycoproteins. | antibodies were raised against carrot (daucus carota) cell wall beta-fructosidase that was either in a native configuration (this serum is called anti-betaf(1)) or chemically deglycosylated (anti-betaf(2)). the two antisera had completely different specificities when tested by immunoblotting. the anti-betaf(1) serum reacted with beta-fructosidase and many other carrot cell wall proteins as well as with many proteins in extracts of bean (phaseolus vulgaris) cotyledons and tobacco (nicotiana tabac ... | 1989 | 16666870 |
| a comparison between quin-2 and aequorin as indicators of cytoplasmic calcium levels in higher plant cell protoplasts. | assessment of the regulation of plant metabolism by the calcium ion requires a knowledge of its intracellular levels and dynamics. technical problems have prevented direct measurement of the concentration of intracellular ca(2+) in plant cells in all but a few cases. in this study we show that electropermeabilized protoplasts of daucus carota and hordeum vulgare took up the ca(2+) indicating fluorescent dye methoxyquinoline(o-aminophenoxy)ethane-n,n,n',n'-tetraacetic acid (quin-2) and the ca(2+) ... | 1989 | 16666797 |
| synthesis of methylated ethanolamine moieties: regulation by choline in soybean and carrot. | cultured cell suspensions of both carrot (daucus carota l.) and soybean (glycine max) take up exogenous choline efficiently from their respective growth media. during sustained growth at a concentration near 50 micromolar choline, this compound was taken up at rates which exceeded those at which phosphatidylcholine, is synthesized by cells growing in standard (i.e. choline-free) media. in 50 micromolar choline, both types of cells metabolized this compound to phosphocholine and phosphatidylcholi ... | 1989 | 16666754 |
| influence of boron on the membrane potential in elodea densa and helianthus annuus roots and h extrusion of suspension cultured daucus carota cells. | when following the membrane potential of elodea densa leaf cells during a dark-light regime and analysing the different phases of the cycle, the pattern under boron deficiency resembled the one reported to occur after 3-(3,4-dichlorophenyl)-1,1-dimethylurea application. the potential in the dark slowly decreased when transferring elodea densa leaflets and helianthus annuus roots to a b-free medium and increased in the same way after b was added again. addition of vanadate to inhibit plasmalemma ... | 1989 | 16666749 |
| udp-glucose: (1,3)-beta-glucan synthase from daucus carota l. : characterization, photoaffinity labeling, and solubilization. | the membrane-bound udp-glucose-beta-(1,3)-glucan synthase from daucus carota l. was characterized and a solubilization procedure was developed. the enzyme exhibited maximal activity in the presence of 0.75 millimolar ca(2+), 0.5 millimolar egta, and 5 millimolar cellobiose at ph 7.5 and 30 degrees c at 1 millimolar udpg. reaction products were confirmed to be (1,3)-linked glucan. polypeptides of 150, 57, and 43 kilodaltons were labeled with the photoactivatible affinity label 5-azido-uridine 5'- ... | 1989 | 16666718 |
| apparent inhibition of beta-fructosidase secretion by tunicamycin may be explained by breakdown of the unglycosylated protein during secretion. | suspension-cultured carrot (daucus carota) cells synthesize and secrete beta-fructosidase, a glycoprotein with asparagine-linked glycans. treatment of the cells with tunicamycin completely inhibits the apparent secretion of beta-fructosidase as measured by the accumulation of the radioactive protein in the cell wall or the culture medium. in the past, such a result has been interpreted as an inhibition of secretion by tunicamycin, but we suggest another explanation based on the following results ... | 1989 | 16666631 |
| characterization of inositol phosphates in carrot (daucus carota l.) cells. | we have shown previously that inositol-1,4,5-trisphosphate (ip(3)) stimulates an efflux of (45)ca(2+) from fusogenic carrot protoplasts (m rincón, wf boss [1987] plant physiol 83: 395-398). in light of these results, we suggested that ip(3) might serve as a second messenger for the mobilization of intracellular ca(2+) in higher plant cells. to determine whether or not ip(3) and other inositol phosphates were present in the carrot cells, the cells were labeled with myo-[2-(3)h]inositol for 18 hou ... | 1989 | 16666502 |
| enzymes of phosphatidylcholine synthesis in lemna, soybean, and carrot. | cell-free extracts from lemna and suspension cultured carrot (daucus carota l.) catalyze s-adenosylmethionine-dependent n-methylations of phosphoethanolamine, phosphomethylethanolamine, and phosphodimethylethanolamine; extracts of suspension cultured soybean (glycine max), of phosphoethanolamine only. material pelleted from each tissue between 15,000 and 100,000g catalyzes s-adenosylmethionine-dependent n-methylations of phosphatidylmethylethanolamine and phosphatidyl-dimethylethanolamine, but n ... | 1988 | 16666464 |
| substrate utilization by suspension cultures and somatic embryos of daucus carota l. measured by c nmr. | the uptake and utilization of sucrose by embryogenic suspension cultures of carrot (daucus carota l.) growing in the presence of 2,4-d and by somatic embryos derived from these cultures was monitored using (13)c nuclear magnetic resonance. the exogeneously supplied sucrose was completely hydrolyzed before cell entry; glucose was taken up preferentially when the cells were cultured in the presence of 2,4-d, while glucose and fructose were utilized at similar rates by somatic embryos in the absenc ... | 1988 | 16666463 |
| promoter strength comparisons of maize shrunken 1 and alcohol dehydrogenase 1 and 2 promoters in mono- and dicotyledonous species. | promoter strengths of two maize alcohol dehydrogenase genes, adh1 and adh2, and the maize shrunken-1 gene, sh1, were evaluated by transient expression in cultured protoplasts of panicum maximum, triticum monococcum, and daucus carota. promoter elements were ligated in correct and opposite orientations as transcriptional gene fusions to the chloramphenicol acetyl transferase gene containing the nopaline synthase 3' polyadenylation signal. the relative levels of gene expression were compared to th ... | 1988 | 16666422 |
| phosphatidylcholine synthesis: differing patterns in soybean and carrot. | the methylation steps in the biosynthesis of phosphatidylcholine by tissue culture preparations of carrot (daucus carota l.) and soybean (glycine max), and by soybean leaf discs, have been studied. preparations were incubated with tracer concentrations of l-[(3)h(3)c]methionine and the kinetics of appearance of radioactivity in phosphomethylethanolamine, phosphodimethylethanolamine, phosphocholine, phosphatidylmethylethanolamine, phosphatidyldimethylethanolamine, phosphatidylcholine, methylethan ... | 1988 | 16666397 |
| plant plasma membrane proteins : ii. biotinylation of daucus carota protoplasts and detection of plasma membrane polypeptides after sds-page. | the ability of two biotinylating reagents, sulfosuccinimidobiotin and sulfosuccinimidyl 2-(biotinamido)ethyl-1,3'-dithiopropionate, to label plasma membrane proteins was examined. these compounds form covalent bonds with the free amino groups of proteins and label the proteins with biotin. biotinylated proteins can be detected with avidin-peroxidase staining. protoplasts isolated from embryogenic daucus carota suspension cells were labeled with biotin and the membranes were separated on linear s ... | 1988 | 16666324 |
| polyamines in relation to growth in carrot cell cultures. | changes in polyamine metabolism were investigated in relation to growth of cell suspension cultures of carrot (daucus carota, cv chantenay). changes in levels of the major amines putrescine and spermidine throughout the culture period correlated poorly with changes in fresh weight, but a closer correlation with the minor component spermine was observed. the arginine decarboxylase (adc) inhibitor difluoromethylarginine (dfma) strongly and specifically inhibited adc activity in the supernatant, re ... | 1988 | 16666271 |
| transport and subcellular localization of polyamines in carrot protoplasts and vacuoles. | putrescine and spermidine uptake in carrot (daucus carota l., cv "tip top") protoplasts and isolated vacuoles was studied. protoplasts and vacuoles accumulated polyamines very quickly, with maximum absorption within 1 to 2 minutes. the insertion of a washing layer containing 100 millimolar unlabeled putrescine or spermidine did not change this pattern, but strongly reduced the uptake of putrescine and spermidine in protoplasts and in vacuoles. the dependence of spermidine uptake on the external ... | 1988 | 16666174 |
| comparison of starch and adp-glucose pyrophosphorylase levels in nonembryogenic cells and developing embryos from induced carrot cultures. | cultures of carrot (daucus carota l.) in a medium without added 2,4-dichlorophenoxyacetic acid were separated into fractions of embryos at different stages of development (large globular and heart, torpedo, and germinating) and nonembryogenic cells. the average starch content per cell in these fractions was similar. however, due to the smaller sizes of the cells of the embryos relative to the nonembryogenic cells, starch content per weight of tissue was higher in the embryos. the adp-glucose pyr ... | 1988 | 16665929 |
| binding of glycolytic enzymes to a particulate fraction in carrot and sugar beet storage roots : dependence on metabolic state. | numerous studies have demonstrated a rapid increase in the respiration rate during aging of slices of tuber and storage roots. to determine the molecular mechanisms of this phenomenon, the role of enzyme binding to the subcellular particulate fraction has been assessed in carrot (daucus carota l.) and sugar beet (beta vulgaris l.). soluble versus particulate fractions were separated by centrifugation at 16,000g and both fractions assayed for the activities of six glycolytic enzymes. preparations ... | 1988 | 16665910 |
| osmotically induced proton extrusion from carrot cells in suspension culture. | addition of 200 mm of a polyol to anthocyanin containing carrot (daucus carota l.) cells in suspension culture decreased turgor pressure to zero and induced hyperpolarization of the membrane potential and acidification of the medium due to h(+) extrusion. these changes were shown to be slightly affected by vanadate. in parallel, a decrease in intracellular atp and total adenylate concentrations were observed. however, when the osmoticum was nacl acidification of the medium occurred in the absenc ... | 1987 | 16665707 |
| control of wild carrot somatic embryo development by antioxidants : a probable mode of action of 2,4-dichlorophenoxyacetic acid. | as we previously reported for glutathione (gsh), both ascorbic acid (aa) and vitamin e were observed to suppress wild carrot (daucus carota l.) somatic embryogenesis with little concomitant effect on biomass. endogenous concentrations of aa were lower during embryo development than during cell proliferation, exhibiting a temporal pattern nearly identical to that of gsh. gssg (oxidized gsh) reductase was found to be considerably more active in proliferating than in developing cultures, whereas no ... | 1987 | 16665669 |
| isolation and characterization of aba-insensitive cell lines of carrot. | while abscisic acid (aba) exerts multiple effects on somatic embryogenesis, the most pronounced of these effects is the arrestment of torpedo-stage embryos, preventing them from developing into plantlets. in order to understand the mechanism of aba inhibition of plantlet formation, we have isolated seven aba-insensitive cell lines capable of developing into plantlets in the presence of aba. these aba-insensitive cell lines, whose frequency of appearance is 7 x 10(-6), have been isolated from a h ... | 1987 | 16665552 |
| polyamine uptake in carrot cell cultures. | putrescine and spermidine uptake into carrot (daucus carota l.) cells in culture was studied. the time course of uptake showed that the two polyamines were very quickly transported into the cells, reaching a maximum absorption within 1 minute. increasing external polyamine concentrations up to 100 millimolar showed the existence of a biphasic system with different affinities at low and high polyamine concentrations. the cellular localization of absorbed polyamines was such that a greater amount ... | 1987 | 16665446 |
| purification of a trypsin inhibitor secreted by embryogenic carrot cells. | a protease inhibitor with a molecular weight of about 12,800 was purified to electrophoretic homogeneity from daucus carota cells. the protease inhibitor was heat stable and inhibited trypsin but had no activity toward chymotrypsin or subtilisin. nonembryogenic as well as embryogenic strains contained the inhibitor in similar amounts, but in the embryogenic strains the trypsin inhibitor was released from the cells and as a result accumulated in high concentrations in the culture medium, whereas ... | 1987 | 16665398 |
| myo-inositol trisphosphate mobilizes calcium from fusogenic carrot (daucus carota l.) protoplasts. | to determine whether or not inositol trisphosphate (ip(3)) mobilizes calcium in higher plant cells, we investigated the effect of ip(3) on ca(2+) fluxes in fusogenic carrot (daucus carota l.) protoplasts. the protoplasts were incubated in (45)ca(2+)-containing medium and the (45)ca(2+) associated with the protoplasts was monitored with time. addition of ip(3) (20 micromolar) caused a 17% net loss of the accumulated (45)ca(2+) within 4 minutes. there was a reuptake of (45)ca(2+) and the protoplas ... | 1987 | 16665256 |
| 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase from potato tuber (solanum tuberosum l.). | 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase, the first enzyme of the shikimate pathway, was purified to electrophoretic homogeneity from tubers of solanum tuberosum l. cv superior. the enzyme is a dimer with a native molecular weight of 110,000. the enzyme appears to be hysteretic. the enzyme activity is stimulated by mn(2+) and l-tryptophan. chromatofocusing resolved two forms of the enzyme with isoelectric points of 7.8 and 8.4, respectively. the enzyme closely resembles an analogous ... | 1986 | 16665132 |
| carbon assimilation in carrot cells in liquid culture. | assimilation of carbohydrates by carrot (daucus carota l. cv danvers) cells in liquid culture was studied to delineate the major metabolic pathways used in transformation of external carbohydrates to udp-glucose. the cells grown on either sucrose or glucose for several years proved equally capable of utilizing each of these sugars. sucrose was rapidly hydrolyzed extracellularly to glucose and fructose, and glucose was preferentially taken up. uptake of fructose was slower and delayed until gluco ... | 1986 | 16665036 |
| potassium transport in suspension culture cells and protoplasts of carrot. | the properties of potassium transport in carrot (daucus carota l.) suspension culture cells and their isolated protoplasts were examined. cells cultured in murashige and skoog (ms) medium (plant physiol 15: 473-497) were potassium saturated and, consequently, they exhibited little net potassium accumulation. cells that transport and accumulate potassium were derived from the ms-grown cells by culturing them in a potassium-free modified medium. the transport properties of the modified medium cell ... | 1986 | 16664937 |
| cross-linking patterns in salt-extractable extensin from carrot cell walls. | extensins are hydroxyproline-rich glycoproteins (hrgps) found in the primary cell walls of dicots. extensin monomers are secreted into the wall and covalently bound to each other, presumably by isodityrosine (idt) cross-links, to form a rigid matrix. expression of the extensin matrix is correlated with inhibition of cell elongation during normal development and with increased resistance to virulent pathogens. we have isolated extensin from carrot root tissue (daucus carota l.) by published techn ... | 1986 | 16664781 |
| calcium transport in tonoplast and endoplasmic reticulum vesicles isolated from cultured carrot cells. | two active calcium (ca(2+)) transport systems have been identified and partially characterized in membrane vesicles isolated from cultured carrot cells (daucus carota danvers). both transport systems required mgatp for activity and were enhanced by 10 millimolar oxalate. ca(2+) transport in membrane vesicles derived from isolated vacuoles equilibrated at 1.10 grams per cubic centimeter and comigrated with cl(-)-stimulated, no(3) (-)-inhibited atpase activity on sucrose density gradients. ca(2+) ... | 1986 | 16664660 |
| identification and isolation of single cells that produce somatic embryos at a high frequency in a carrot suspension culture. | a system was established in which single cells differentiated to embryos at a high frequency. small spherical single cells from a carrot (daucus carota l. cv "kurodagosun") cell suspension culture were obtained by fractionation through sieving, using nylon screens and then density gradient centrifugation in percoll solutions. eighty-five to 90% of these small single cells differentiated to embryos when they were cultured in a medium containing 2,4-dichlorophenoxyacetic acid (5 x 10(-8) molar), z ... | 1985 | 16664558 |
| 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase from carrot root (daucus carota) is a hysteretic enzyme. | roots of carrots (daucus carota) contain three activities of 3-deoxy-d-arabino-heptulosonate 7-phosphate (dahp) synthase, the enzyme that catalyzes the first step of the shikimate pathway. the three activities, enzymes i, ii, and iii, are separated by chromatography on phosphocellulose. enzyme iii, purified to electrophoretic homogeneity, has a native molecular weight of 103,000 and consists of two identical subunits of 53,000 daltons each. double reciprocal plots of reaction velocity versus sub ... | 1985 | 16664489 |
| intracellular calcium and calmodulin involvement in protoplast fusion. | (45)ca(2+) uptake was compared between fusogenic and nonfusogenic daucus carota l. protoplasts. fusogenic protoplasts took 10 minutes to reach calcium equilibrium compared to 5 minutes in the nonfusogenic protoplasts. intracellular stores of calcium were manipulated by isolating protoplasts in different calcium regimes. lowering of intracellular calcium lowered fusion potential, while raising intracellular stores of calcium enhanced fusion potential. regardless of the amount of calcium sequester ... | 1985 | 16664381 |
| isolation and partial purification of prophenoloxidase from daucus carota l. cell cultures. | the enzyme, phenoloxidase, was isolated and partially purified as an inactive enzyme, a proenzyme, from plant cell cultures of daucus carota, nicotiana tabacum, and haplopappus gracilis. the prophenoloxidase was found to be specifically activated by ca(2+) or mn(2+) ions in concentrations above 1 millimolar. calmodulin was not involved in this activation. concentrations of ca(2+) or mn(2+) below 1 millimolar could not induce activation of the prophenoloxidase, but if trypsin was added simultaneo ... | 1985 | 16664316 |
| localization of cytokinin biosynthetic sites in pea plants and carrot roots. | the biosynthesis of cytokinins was examined in pea (pisum sativum l.) plant organs and carrot (daucus carota l.) root tissues. when pea roots, stems, and leaves were grown separately for three weeks on a culture medium containing [8-(14)c]adenine without an exogenous supply of cytokinin and auxin, radioactive cytokinins were synthesized by each of these organs. incubation of carrot root cambium and noncambium tissues for three days in a liquid culture medium containing [8-(14)c]adenine without c ... | 1985 | 16664274 |
| trehalose as cryoprotectant for the freeze preservation of carrot and tobacco cells. | suspension cultures of carrot (daucus carota, line c1), tobacco (nicotiana tabacum, line tx1), and nicotiana plumbaginifolia (line np) were frozen under controlled conditions with trehalose as the sole cryoprotectant. maximal post-thaw viability (71-74%), measured by phenosafranin dye exclusion, was obtained with the c1 cells following a 24hour pretreatment with 5 or 10% trehalose and with 40% trehalose as the cryoprotectant during freezing. tx1 cells pretreated for 24 hours with 10% trehalose a ... | 1985 | 16664260 |
| sensitivity of carrot cell cultures and rna polymerase ii to amatoxins : evidence for the inactivation of 6'-hydroxyamatoxins. | protoplast and cell suspension cultures of daucus carota l. were evaluated for their sensitivity toward the three amatoxin derivatives, alpha-amanitin, 6'-deoxy-alpha-amanitin, and 6'-o-methyl-alpha-amanitin using inhibition of dna synthesis to measure cell viability. protoplasts appeared approximately 10-fold more refractory than suspension cells and alpha-amanitin was much less effective than the other two amatoxins, even though k(i) values for isolated rna polymerase ii were similar (4-5 nano ... | 1985 | 16664072 |
| virulence properties of strains of agrobacterium on the apical and basal surfaces of carrot root discs. | most pathogenic strains of agrobacterium are able to induce crown gall or hairy root on both the apical surface (facing the root tip) and the basal surface (facing the shoot) of carrot (daucus carota l.) root discs. tumorigenic strains carrying mutations in the shoot inhibition region of the t-dna (tl-dna genes 1 and 2) are markedly attenuated on the basal surface but remain virulent on the apical surface. coinoculation of two attenuated tumorigenic strains, with mutations in gene 1 and gene 2, ... | 1985 | 16664012 |
| selection and characterization of a carrot cell line tolerant to glyphosate. | cultured carrot (daucus carota l.) cells were adapted to growing in 25 millimolar glyphosate by transfer into progressively higher concentrations of the herbicide. tolerance was increased 52-fold, and the adaptation was stable in the absence of glyphosate. the uptake of glyphosate was similar for adapted and nonadapted cells. activity of the enzyme 5-enolpyruvylshikimic acid-3-phosphate synthase was 12-fold higher in the adapted line compared to nonadapted cells, while activities of shikimate de ... | 1984 | 16663884 |
| cross-linking of soluble extensin in isolated cell walls. | the extensin component of primary cell walls has generally been considered to be an intrinsically insoluble cell wall glycoprotein. recent data have established that cell wall extensin is in fact secreted in a soluble monomeric form which slowly becomes insolubilized in the cell wall probably through the oxidative formation of isodityrosine cross-links. we now show that isolated cell walls from aerated root slices of daucus carota have the capacity to insolubilize extensin through the formation ... | 1984 | 16663856 |
| regulation of the shikimate pathway of carrot cells in suspension culture. | the activity of the first enzyme of the shikimate pathway, 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase, is demonstrated in extracts of daucus carota cells grown in suspension culture. maximum specific enzyme activity is found midway through the logarithmic growth of the culture; cells in lag and stationary phases of growth have lower enzyme levels. the enzyme is activated by tyrosine and tryptophan. the extent of activation varies during cell growth. | 1984 | 16663628 |
| comparative effects of ethylene and cyanide on respiration, polysome prevalence, and gene expression in carrot roots. | treatment of carrot roots (daucus carota l.) with 10 microliters per liter ethylene in o(2) evokes a three- to four-fold increase in polysome prevalence and associated poly(a)(+) rna. the increase in polysome prevalence is attended by a similar change in co(2) evolution. the increase in polysomal poly(a)(+) mrna constitutes primarily a generic increase in constitutive mrnas as assayed by in vitro translation. however, changes in the relative abundance of several in vitro translatable ethylene sp ... | 1984 | 16663623 |
| reinforced polyproline ii conformation in a hydroxyproline-rich cell wall glycoprotein from carrot root. | the salt-extractable hydroxyproline-rich cell wall glycoprotein from carrot (daucus carota l.) roots is composed of 35% (w/w) protein, 3% (w/w) galactose, and 62% (w/w) arabinose. the arabinose is attached to hydroxyproline as tetra- and trisaccharides. the circular dichroism of the glycoprotein shows that it is completely in the polyproline ii conformation. after deglycosylation of the glycoprotein, the polyproline ii conformation of the peptide backbone was lost. this indicates that the carboh ... | 1984 | 16663405 |
| orientation and integrity of plasma membrane vesicles obtained from carrot protoplasts. | two fractions enriched in plasma membrane derived from suspension-cultured carrot (daucus carota l.) cells were examined to determine if they differed from each other either in physical nature or in orientation. parameters studied included the protein composition of purified membranes derived from trypsinized and nontrypsinized protoplasts as well as from trypsinized purified plasma membranes, the effect of inhibitors and membrane perturbants on atpase activity, the binding of [acetyl-(14)c]conc ... | 1983 | 16663225 |
| selective inhibition of proline hydroxylation by 3,4-dehydroproline. | the effect of proline analogs on peptidyl proline hydroxylation has been studied in vivo using aerated root slices of daucus carota. one analog, 3,4-dehydroproline, acted at micromolar concentrations to rapidly and selectively inhibit peptidyl proline hydroxylation. a structurally altered hydroxyproline-rich cell wall glycoprotein was synthesized and secreted by dehydroproline-treated tissue. the capacity to hydroxylate proline recovered slowly following a short pulse treatment with the analog, ... | 1983 | 16663215 |
| ozone degrades into hydroxyl radical under physiological conditions : a spin trapping study. | defining the reactants is a critical step towards elucidating the mechanism of ozone toxicity to biomembranes. to document ozone-induced ho.radicals, the spin trap 5,5-dimethyl-1-pyrroline-n-oxide was used and the resulting spin adduct was monitored with electron spin resonance spectroscopy. chelexed potassium phosphate buffer (10 millimolar and 0.2 molar) at ph 7.2 and 7.8 was exposed to ozone (1-40 microliters per liter) by directing a stream of ozone over the surface for 60 seconds. under the ... | 1983 | 16663113 |
| characteristics of sulfate transport across plasmalemma and tonoplast of carrot root cells. | compartmental analysis of (35)so(4) (2-) exchange kinetics is used to obtain so(4) (2-) fluxes and compartment contents in carrot (daucus carota l.) storage root cells, where 2 to 5% of the so(4) (2-) taken up is reduced to organic form. the necessary curve fitting is verified by (a) consistency between ;content versus time' and ;rate versus time' plots of washout data; (b) agreement between loading and washout kinetics; and (c) correct identification of the fastest exchange phase as being from ... | 1983 | 16662961 |
| effects of aspartate and other compounds on glyphosate uptake and growth inhibition in cultured carrot cells. | the strong correlation between glyphosate uptake and growth inhibition of cultured carrot (daucus carota l. cv danvers) cells incubated in the presence of aspartate suggests that aspartate reverses glyphosate inhibition of growth primarily by reducing intracellular glyphosate concentration. other compounds which reverse glyphosate inhibition of cell growth gave a range of effects on glyphosate uptake: succinate, alpha-ketoglutarate, glutamate, pyruvate, and malate at 10 millimolar and phenylalan ... | 1983 | 16662877 |
| characterization of a selenocystine-resistant carrot cell line : alterations in cystine and sulfate uptake. | a selenocystine-resistant carrot cell line, c-1, was isolated from a haploid carrot (daucus carota) cell culture, ha. the c-1 variant takes up cystine, but not cysteine, more slowly than does ha. the selenocystine resistance is maintained in culture in the absence of selection and is expressed in regenerated plants. results based on chromatographic separation of sulfur metabolites from cells fed with [(35)s]cystine suggest a block either in the uptake or reduction of cystine in the variant. both ... | 1983 | 16662864 |
| cryostorage of cloned amino acid analog-resistant carrot and tobacco suspension cultures. | five clones were isolated from five different amino acid analog-resistant daucus carota l. var. sativa and nicotiana tabacum l. cv. xanthi cell lines. the individual clones were similar in their resistance to dl-5-methyltryptophan, s-(2-aminoethyl)-l-cysteine, or azetidine-2-carboxylic acid, and in their corresponding free amino acid levels.the cell suspensions were stored using a controlled freezing rate at -196 degrees c with concentrations up to 40% of the four cryoprotectants: mannitol, prol ... | 1982 | 16662465 |
| potentiating effect of pure oxygen on the enhancement of respiration by ethylene in plant storage organs: a comparative study. | a number of fruits and bulky storage organs were studied with respect to the effect of pure o(2) on the extent and time-course of the respiratory rise induced by ethylene. in one group, of which potato (solanum tuberosum var. russet) and carrot (daucus carota) are examples, the response to ethylene in o(2) is much greater than in air. in a second group, of which avocado (persea americana mill. var. hass) and banana (musa cavendishii lambert var. valery) are examples, air and o(2) are equally eff ... | 1982 | 16662339 |
| studies on the pectic substances of plant cell walls: iii. degradation of carrot root cell walls by endopectate lyase purified from erwinia aroideae. | pectate lyase was isolated from the cell extract of erwinia aroideae. the enzyme was further purified to a high degree by a procedure involving ammonium sulfate fractionation and chromatography on cm-sephadex c-50 and on sephadex g-200. the enzyme attacked its substrate in an endo fashion and was more active on the sodium salt of acid-insoluble polygalacturonate or pectic acid than it was on the methoxylated pectin. the enzyme had an optimum ph at 9.3, was stimulated by calcium ions, and was com ... | 1982 | 16662310 |
| homology of plant peroxidases: an immunochemical approach. | antisera specific for the basic peroxidase from horseradish (amoracea rusticana) were used to examine homology among horseradish peroxidase isoenzymes and among basic peroxidases from root plants. the antisera cross-reacted with all tested isoperoxidases when measured by both agar diffusion and quantitative precipitin reactions. precipitin analyses provided quantitative measurements of homology among these plant peroxidases. the basic radish (raphanus sativus l. cv. cherry belle) peroxidase had ... | 1982 | 16662176 |
| reversal of glyphosate inhibition of carrot cell culture growth by glycolytic intermediates and organic and amino acids. | various cytokinins and purines were ineffective in reversing glyphosate (0.25 millimolar)-induced growth inhibition of carrot (daucus carota l.) cell suspension cultures. aspartate was particularly effective in reversing glyphosate inhibition, but asparagine and various combinations of lysine, methionine, threonine, and homoserine (eventual products of aspartate metabolism) were not effective. when organic acids of the tricarboxylic acid cycle were added to the medium, particularly good reversal ... | 1981 | 16662096 |
| transfer of liposome-sequestering plasmid dna into daucus carota protoplasts. | reverse-phase evaporation lipid vesicles (rev) liposomes, consisting of phosphatidyl choline and stearylamine in 1:3 molar ratio, encapsulated approximately 30% of exogenously supplied recombinant dna vector, pbr322. the dna sequestered in rev liposomes was highly tolerant to dnase.a two-step procedure was developed, which involves encapsulation of dna with liposomes using one-tenth phosphate-buffered saline-0.5 molar mannitol, followed by incubation of liposome-dna with protoplasts in phosphate ... | 1981 | 16662045 |
| characterization of carrot cell wall protein : ii. immunological study of cell wall protein. | antiserum was raised against a synthetic nona-peptide which was predicted to have considerable homology with the unhydroxylated, unglycosylated precursor of cell wall proteins from several plants. the antiserum is able to recognize the major cell wall protein of incubated carrot (daucus carota) root discs which is produced when the discs are treated with a proline hydroxylase inhibitor and then labeled with radioactive proline. this technique has potential applications in studying cell wall bios ... | 1981 | 16662034 |
| characterization of carrot cell wall protein : i. effect of alpha, alpha'-dipyridyl on cell wall protein synthesis and secretion in incubated carrot discs. | a single glycoprotein accounts for the majority of radioactivity secreted to the cell wall when incubated carrot (daucus carota) discs are labeled with radioactive proline or arabinose. the ferrous chelator alpha,alpha'-dipyridyl prevents the synthesis of this protein. a new proline-labeled protein is made in the presence of alpha,alpha'-dipyridyl and is secreted to the cell wall. the protein has little, if any, carbohydrate attached to it and has a molecular weight of 55,000 daltons. this prote ... | 1981 | 16662033 |
| parameters influencing the liposome-mediated insertion of fluorescein diacetate into plant protoplasts. | maximum uptake of liposome-encapsulated fluorescein diacetate by daucus carota protoplasts was observed when 6 x 10(6) protoplasts per milliliter were incubated with 2.4 x 10(7) liposomes per milliliter for 1 hour. in the case of nicotiana glutinosa protoplasts, optimum ratio of protoplasts to liposomes was 1:10, where 2.3 x 10(5) protoplasts per milliliter were provided. neutral and positive liposomes were found to be efficient vehicles to transfer their contents into plant protoplasts. when pr ... | 1981 | 16661727 |
| synchronization of somatic embryogenesis in a carrot cell suspension culture. | synchronization of somatic embryogenesis was achieved in a carrot (daucus carota l. cv. "kurodagosun") suspension culture by sieving the initial heterogeneous cell population, by density gradient centrifugation in ficoll solutions, and by subsequent repeated centrifugations at a low speed (50g) for a short time (5 seconds), followed by transferring the cell clusters obtained, which were composed of 3 to 10 cells, to a medium containing zeatin (0.1 micromolar) but no auxin. the frequency of embry ... | 1979 | 16660907 |
| temperature interactions with growth regulators and endogenous gibberellin-like activity during seedstalk elongation in carrots. | stecklings (roots) of three cultivars of carrots (daucus carota l.) were vernalized 10 weeks at 5 c and subsequently grown at each of three greenhouse night/day temperature regimes: high (27/32 c), medium (21/27 c), and low (15/21 c). floral differentiation occurred first in the easy bolting cv. scarlet nantes, intermediate in cv. danvers 126, and last in cv. royal chantenay. stem elongation arising from the subapical meristematic region always preceded floral differentiation. extractable gibber ... | 1979 | 16660856 |
| amino acid levels in carrot cell suspension culture: no correlation with aspartate kinase isoenzyme levels. | free and protein amino acids were analyzed during the growth cycle of a suspension culture of carrot (daucus carota l.) in which there is a 10-fold increase in a lysine-sensitive isoenzyme of aspartate kinase during the early part of the growth cycle. there is little change in either total amino acids or in the amino acids derived from aspartate between 3 and 24 days of culture. it is estimated that the demand for net synthesis of aspartate-derived amino acids is decreased as the growth rate dec ... | 1979 | 16660772 |
| derepression and repression of lysine-sensitive aspartokinase during in vitro culture of carrot root tissue. | the increment of lysine-sensitive aspartokinase (ec 2.7.2.4) activity during in vitro culture of carrot (daucus carota, cv. oogata sanzun) root tissue was explained in terms of derepression caused by an earlier decrease in the endogenous level of lysine, a possible end product repressor. tissue content of free lysine decreased to about one-third of the initial level after 1 day of culture and no lysine was detected in the 2nd day. inclusion of lysine (0.1 to 1.0 millimolar) in the culture medium ... | 1979 | 16660771 |
| freeze preservation of somatic embryos and clonal plantlets of carrot (daucus carota l). | cell suspensions of carrot (daucus carota l.) can be cryopreserved by slow freezing (about 2 c per minute) in medium containing dimethylsulfoxide as a cryoprotectant. after storage in liquid nitrogen and thawing they demonstrate a high viability and are able to resume growth. such a method entirely fails to preserve clonal plantlets; somatic embryos cease organized development at the time of freezing and recover growth only by secondary embryogenesis. modification of the procedure, involving the ... | 1979 | 16660748 |
| polyamine metabolism in embryogenic cells of daucus carota: ii. changes in arginine decarboxylase activity. | embryogenic cultured cells of daucus carota have been shown to synthesize putrescine from exogenously supplied [(14)c]arginine at twice the rate of control nonembryogenic cells. in the present paper, the activity of arginine decarboxylase (arginine carboxy-lyase, ec 4.1.1.19), an important enzyme in the synthesis of putrescine, was assayed and also found to be elevated by as much as 2-fold in embryogenic cells. this difference between embryogenic and nonembryogenic cells was observed as early as ... | 1979 | 16660725 |
| regulatory isoenzymes of aspartate kinase and the control of lysine and threonine biosynthesis in carrot cell suspension culture. | aspartate kinase (ec 2.7.2.4) from carrot (daucus carota l.) cell suspension culture has been partially resolved into lysine-sensitive and threonine-sensitive components by gel filtration chromatography. the yield of lysine-sensitive aspartate kinase changed independently of the yield of the threonine-sensitive activity during the 4-week growth cycle of the culture, and this provides additional evidence for the existence of two independently regulated isoenzymes. exogenously supplied lysine and ... | 1978 | 16660554 |
| polyamine metabolism in embryogenic cells of daucus carota: i. changes in intracellular content and rates of synthesis. | changes in the metabolism of polyamines, which seem to be involved in transcription and translation in animal systems, have been studied in cultured cells of daucus carota (carrot) undergoing embryogenesis. putrescine levels were elevated by as much as 2-fold over the control within 24 hours after transfer of the cells to embryogenic medium. spermidine levels were elevated also but spermine levels appeared to be lower in embryogenic cells. embryogenic cells incorporated [(14)c]arginine into putr ... | 1978 | 16660531 |
| bacitracin inhibits the synthesis of lipid-linked saccharides and glycoproteins in plants. | the particulate enzyme fraction from mung bean (phaseolus aureus) seedlings catalyzes the incorporation of mannose from gdp-[(14)c]mannose into mannosyl-phosphoryl-dolichol and of n-acetylglucosamine from udp-[(3)h]n-acetylglucosamine into n-acetylglucosamine-pyrophosphoryl-polyisoprenol. bacitracin inhibits the transfer of both of these sugars into the lipid-linked saccharides with 50% inhibition being observed at 5 mm bacitracin. this antibiotic did not inhibit the transfer of glucose from udp ... | 1978 | 16660520 |
| inhibition of deoxyribonuclease activity in the medium surrounding plant protoplasts. | after 1 hour, exogenous deoxyribonucleic acid was degraded within a culture medium at 25 c (ph 6) containing protoplasts of daucus carota l. var. sativa. low temperature incubation (1 c) or the addition of 45 millimolar sodium citrate to the medium eliminated dnase activity for at least 4.5 hours. this dnase activity was not reduced at ph 7 or 9, nor by addition of 200 millimolar adenosine 5'-triphosphate.techniques were developed to ensure high protoplast plating efficiencies and high regenerat ... | 1978 | 16660499 |
| change in the proportion of two aspartokinases in carrot root tissue in response to in vitro culture. | two isofunctional aspartokinases (ec 2.7.2.4) exist in fresh root tissue of carrot (daucus carota, cv. oogata sanzun). the threoninesensitive portion constitutes about 70% of the activity; the lysinesensitive, less than 20%. culture of slices of carrot tissue for 3 days reversed the ratio as the lysine-sensitive activity preferentially increased. inhibition by threonine and lysine was additive in both enzyme preparations from fresh and cultured tissues. the activities were resolved into two dist ... | 1978 | 16660222 |
| effects of ethephon, ethylene, and 2,4-dichlorophenoxyacetic acid on asexual embryogenesis in vitro. | asexual embryogenesis in daucus carota l. ;queen anne's lace' callus was suppressed by ethephon, ethylene, and 2,4-dichlorophenoxyacetic acid (2,4-d). the ethephon effect could be attributed to volatile and nonvolatile substances. the volatile component was probably entirely ethylene. ethylene was liberated in the cultures in direct proportion to ethephon added to the medium. autoclaving of ethephon caused a substantial decrease of measurable ethylene. continuous exposure of callus to 5 mul/l et ... | 1977 | 16660109 |
| effect of glyphosate on carrot and tobacco cells. | the growth of suspension-cultured carrot (daucus carota l.) and tobacco (nicotiana tabacum l. cv. xanthi) cells was inhibited by glyphosate (n-[phosphonomethyl]glycine). this inhibition was reversed by adding combinations of phenylalanine, tyrosine, and tryptophan or casein hydrolysate. casein hydrolysate and phenylalanine + tyrosine + tryptophan were the most effective treatments. reversal of glyphosate-induced inhibition occurred only if the aromatic amino acids were added during the first 8 d ... | 1977 | 16660038 |
| effects of ophiobolin a on ion leakage and hexose uptake by maize roots. | ophiobolin a, a sesterterpene metabolite of helminthosporium maydis, nisikado and miyake, stimulates net leakage of electrolytes and glucose from maize (zea mays l.) seedling roots. treatment of the roots with ophiobolin a at a concentration of 10 mug/ml (25 mum) inhibits uptake of 10 mm 2-deoxyglucose by 50% and of 0.5 mm 2-deoxyglucose by 85%. compartmental analysis of the efflux of 3-o-methylglucose failed to show a similar effect of ophiobolin a on the rate of efflux of hexose. the inhibitio ... | 1977 | 16659965 |
| correlation between phenylalanine ammonia lyase activity and phenolic biosynthesis in p-fluorophenylalanine-sensitive and -resistant tobacco and carrot tissue cultures. | phenylalanine ammonia lyase (pal) activity was measured in p-fluorophenylalanine (pfp)-sensitive and -resistant tobacco (nicotiana tabacum l.) and carrot (daucus carota l.) cell lines which are known to oversynthesize phenylalanine. a correlation between phenolic levels and pal activities was detected. the phenylalanine analog-resistant and -sensitive carrot cells showed no differences in the accumulation of phenolic compounds and pal activities. the pfp-resistant tobacco cells, however, had 10 ... | 1977 | 16659891 |
| influence of carbohydrates on quantitative aspects of growth and embryo formation in wild carrot suspension cultures. | wild carrot (daucus carota l.) cell suspensions were grown on a mineral salt medium supplemented with 10 mmmyoinositol in the presence and absence of 2.25 mum 2,4-dichlorophenoxyacetic acid (2,4-d), and a variety of carbon sources.the data obtained on growth and embryo number in the absence of 2,4-d show that wild carrot suspensions were able to utilize sucrose, glucose, fructose, galactose, mannose, maltose, raffinose, or stachyose as a carbon source. a highly significant correlation between dr ... | 1977 | 16659793 |
| variation in germination and amino acid leakage of seeds with temperature related to membrane phase change. | leakages of amino acids and/or fluorescent material as functions of temperature between 15 and 40 c are reported for imbibed seeds of avena fatua l., lactuca sativa l., barbarea vulgaris r. br., amaranthus albus l., abutilon theophrasti medic., lychnis alba mill., daucus carota l., setaria faberi herrm., setaria viridis (l.) beauv., and datura stramonium l. the leakage indicates prominent increase in permeability of the plasmalemma in the 30 to 35 c range for 8 of the 10 kinds of seeds studied. ... | 1976 | 16659623 |
| trypsin-induced atpase activity in potato mitochondria. | potato mitochondria (solanum tuberosum var. russet burbank), which readily phosphorylate adp in oxidative phosphorylation, show low levels of atpase activity which is stimulated neither by mg(2+), 2,4-dinitrophenol, incubation with respiratory substrates, nor disruption by sonication or treatment with triton x-100, individually or in concert. treatment of disrupted potato mitochondria with trypsin stimulates mg(2+)-dependent, oligomycin-sensitive atpase activity 10- to 15-fold, suggesting the pr ... | 1976 | 16659532 |
| a method for eliminating the contribution of agrobacterium tumefaciens to studies of nucleic acid biosynthesis in crown gall tumors. | a procedure is described that permits the use of radiotracer methods for examining crown gall tumors in the presence of the initiating agent agrobacterium tumefaciens. on the basis of sensitivity testing using the disc diffusion technique and the minimum inhibitory concentration procedure and incorporation of radioactive phosphorus into nucleic acids, it was determined that a. tumefaciens was most sensitive to tetracycline, oxytetracycline, and methacycline. it was further demonstrated that nucl ... | 1976 | 16659494 |
| nitrogen metabolism in plant cell suspension cultures: i. effect of amino acids on growth. | certain amino acids inhibit growth of tobacco (nicotiana tabacum l. var. xanthi), tomato (lycopersicon esculentum) carrot (daucus carota), and soybean (glycerine max l. co. mandarin) cell cultures when nitrate or urea are the nitrogen sources but not when ammonia is the nitrogen source. these amino acids also inhibit development of nitrate reductase activity (nadh:nitrate oxidoreductase ec 1.6.6.1) in tobacco and tomato cultures. threonine, the most inhibitory amino acid, also inhibits nitrate u ... | 1975 | 16659349 |
| characterization of carrot and tobacco cell cultures resistant to p-fluorophenylalanine. | this study describes the isolation and characterization of p-fluorophenylalanine-resistant diploid tobacco (nicotiana tabacum l.) and diploid carrot (daucus carota l.) cultured cell lines. the p-fluorophenylalanine-resistant tobacco and carrot lines can grow in medium containing p-fluorophenylalanine concentrations 10 to more than 100 times those which inhibit the growth of susceptible cells, respectively. the resistance trait was retained when the cells were grown in a medium lacking the phenyl ... | 1975 | 16659278 |
| determination of structure and composition of suberin from the roots of carrot, parsnip, rutabaga, turnip, red beet, and sweet potato by combined gas-liquid chromatography and mass spectrometry. | suberin from the roots of carrots (daucus carota), parsnip (pastinaca sativa), rutabaga (brassica napobrassica), turnip (brassica rapa), red beet (beta vulgaris), and sweet potato (ipomoea batatas) was isolated by a combination of chemical and enzymatic techniques. finely powdered suberin was depolymerized with 14% bf(3) in methanol, and soluble monomers (20-50% of suberin) were fractionated into phenolic (<10%) and aliphatic (13-35%) fractions. the aliphatic fractions consisted mainly of omega- ... | 1975 | 16659124 |
| involvement of the golgi apparatus in the synthesis and secretion of hydroxyproline-rich cell wall glycoproteins. | pulse labeling of carrot root phloem parenchyma (daucus carota l. cv. nantes) tissue with (14)c-proline followed by fractionation of the cytoplasmic organelles on sucrose gradients was used to determine the identity of the membranous organelles involved in the secretion of the hydroxyproline-rich glycoproteins of the cell wall. identification of the organelles was done through electron-microscopical observations and through the localization of marker enzymes on the sucrose gradients. enrichment ... | 1975 | 16659117 |
| cell wall and protoplast isoperoxidases in relation to injury, indoleacetic acid, and ethylene effects. | in tobacco (nicotiana tabacum) pith, sweet potato (ipomoea batatas), and carrot (daucus carota) storage roots, differences were found between cell wall and protoplast peroxidases in their isoenzyme patterns, activity, and reaction to tissue injury.in the pith of elongating tobacco internodes, 90% of total activity was associated with the walls, 80% of which was due to the ionically and covalently bound fractions. with senescence, the increase in activity occurred mainly in the protoplast and the ... | 1974 | 16658744 |
| fluxes of a nonelectrolyte and compartmentation in cells of carrot root tissue. | permeation of thiourea into cells of carrot (daucus carota l.) storage root discs was found to be governed by its concentration gradient only. the analysis of the course of thiourea efflux from preloaded discs shows two distinct exponential curves, apart from an initial very fast component. reasons are given for relating the first exponential part of the curve to efflux from the cytoplasm and the second exponential part to efflux from the vacuole.the rate constant for thiourea efflux through the ... | 1974 | 16658696 |
| ethylene-induced phenylalanine ammonia-lyase activity in carrot roots. | ethylene enhanced the activity of phenylalanine ammonialyase in carrot (daucus carota l., var. "nauty") root tissue. slight increase in enzyme activity was exhibited by root discs incubated in ethylene-free air. it was probably due to the ethylene formed within the sliced tissue. addition of ethylene to the air stream increased phenylalanine ammonia-lyase activity and the total protein content of the discs until maximum activity was reached after 36 to 48 hours of incubation. the continuous pres ... | 1973 | 16658459 |
| further studies on the photosynthesis of carrot tissue cultures. | the influence of kinetin and sucrose on the photosynthetic activity of carrot (daucus carota) tissue cultures in relation to growth was investigated. the results showed that light contributes heavily to the growth of tissue cultures measured in terms of fresh and dry weight and cell division activity. in light, the fresh weight, dry weight, and number of cells per explant were about or more than doubled. this indicated that after the development of chloroplasts, carrot tissue cultures can grow a ... | 1973 | 16658393 |
| isolation and properties of deoxyribonucleic acid from protoplasts of cell suspension cultures of ammi visnaga and carrot (daucus carota). | a procedure is described for the isolation of native dna from protoplasts of ammi (ammi visnaga) and carrot (daucus carota) cells. protoplasts were produced from 40 grams of fresh cells by enzyme hydrolysis and lysed with sodium dodecyl sulfate. the dna was purified by treatment with pronase and ribonuclease. final isolation was achieved by sucrose density gradient centrifugation.the melting temperature of ammi and carrot dna in 0.15 m nacl and 15 mm trisodium citrate buffer, ph 7.0, was 84.0 c ... | 1972 | 16658166 |
| induced changes in permeability of plant cell membranes to water. | the half-time for tho equilibration was three times longer for a living carrot (daucus carota l.) cylinder than for a dead one. furthermore, the energy of activation of tho flux was more than twice as high for the living cylinder. passage through living membranes thus constitutes a rate-limiting step for tho flux in carrot tissue.co(2) increased the half-time (t((1/2))) for tho equilibration. treatment with abscisic acid or with tertiary butanol decreased t((1/2)). in neither case was the select ... | 1972 | 16658009 |
| correlation between the suppression of glucose and phosphate uptake and the release of protein from viable carrot root cells treated with monovalent cations. | treating carrot (daucus carota l.) discs with ice-cold nacl solutions for 30 minutes caused three effects that appear to be functionally related: the exchange of tissue ca(2+) and mg(2+) for na(+), the release of protein, and the suppression of active uptake of glucose and orthophosphate. cyclosis continued apparently unabated after treatment with nacl at concentrations of up to 0.25 m, so the cells remained viable and energetically competent. the correlation between the release of ca(2+) and mg ... | 1971 | 16657783 |
| translocation of nickel in xylem exudate of plants. | topped plants of tomato (lycopersicon esculentum), cucumber (cucumis sativus), corn (zea mays), carrot (daucus carota), and peanut (arachis hypogaea) were treated with 0.5 to 50 micromolar ni (containing (63)ni) in nutrient solutions. xylem exudate was collected for 10 hours or, in the case of corn, for 20 hours at 5-hour intervals. electrophoresis of nutrient solution distributed all ni cathodically as inorganic ni(2+). low concentrations of ni in tomato exudate migrated anodically, presumably ... | 1971 | 16657780 |
| phytochrome in cultured wild carrot tissue: ii. dark transformations. | disappearance and transformation of phytochrome in light-treated, dark-grown cultured tissue of wild carrot (daucus carota l.) have been analyzed. evidence is presented for the existence of two populations of far red-absorbing phytochromes: one which is subject to reversion, and a second which undergoes loss of photoreversibility. phytochrome levels and transformation characteristics have been compared for several strains and developmental stages of cultured wild carrot tissue. | 1970 | 16657464 |
| synthesis and secretion of hydroxyproline containing macromolecules in carrots. i. kinetic analysis. | when disks of carrot (daucus carota) phloem parenchyma are incubated for 6 days there is a 10-fold increase in cell wall hydroxyproline due to the synthesis and secretion of hydroxyproline-containing macromolecules. the synthesis of these molecules and their secretion are demonstrated by measuring the kinetics of incorporation and of chase of (14)c-proline and hydroxyproline in different fractions of the cytoplasm and the cell wall. the hydroxyproline-containing molecules which are secreted are ... | 1969 | 16657187 |
| transport of 3-o-methylglucose into and out of storage cells of daucus carota. | the movement of labeled 3-o-methylglucose (meg) into and out of thin carrot discs has been followed in order to gain information on sugar entry and exit mechanisms. little or no metabolism of this derivative appears to occur in the tissue, since no products were detected either by chromatography or by analysis of respiratory co(2).the curve relating entry to external concentration deviated somewhat from a rectangular hyperbola but suggested a carrier mechanism. glucose and meg each competitively ... | 1968 | 16656877 |
| distribution of an indoleacetic acid-oxidase-inhibitor in the storage root of daucus carota. | indoleacetic acid (iaa)-oxidase from both secondary phloem and xylem was dependent on 2,4-dichlorophenol for activity, and was enhanced by addition of mn(2+). the ph optimum was 6.0 from both tissues. iaa-oxidase and its inhibitors were distributed differently in the secondary phloem and secondary xylem of carrot root. in the phloem a high iaa-oxidase activity was distributed uniformly along the radius but in the xylem a somewhat lower concentration decreased from the cambium. iaa-oxidase inhibi ... | 1967 | 16656541 |
| high phytochrome levels in cultured tissue of the wild carrot, daucus carota. | 1967 | 16656507 |