Publications

selection of daucus carota somatic hybrids using drug resistance markers and characterization of their mitochondrial genomes.	protoplasts from different daucus carota l. cell strains carrying resistance to glyphosate, 5-methyltryptophan, sodium selenate or selenocystine were fused in three combinations using dextran. clones were selected for both of the resistances carried by the individual parental strains in medium with both inhibitors. no doubly resistant colonies formed from unfused controls or from protoplasts from each individual parental strain alone. suspension cultures from the selected clones contained predom ...	1986	24248022
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
in vitro inhibition of carrot chalcone synthase by 3'-nucleotidase: the role of the 3'-phosphate group of malonyl-coenzyme a in flavonoid biosynthesis.	in mixing experiments with extracts derived from two cell lines of daucus carota tissue cultures with and without chalcone synthase activity, strong inhibition of chalcone synthase (chs) became obvious. this inhibition was due to the presence of a heatlabile protein in extracts from cells devoid of chs activity. this protein was partially purified and identified as 3'-nucleotidase (ec 3.1.3.6). inhibition was also observed in the presence of purified 3'-nucleotidase from lolium multiflorum. the ...	1986	3008651
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
factors affecting protoplast electrofusion efficiency.	the electrofusion efficiency of protoplasts isolated from a carrot (daucus carota) suspension culture was increased by treatment with 0.1 mg/ml lysolecithin, 2.5% dimethylsulfoxide (dmso), or 0.5 mm ca(2+). the lysolecithin and dmso treatments substantially increased protoplast lysis, whereas calcium treatment did not. the enzymes used for protoplast isolation were also found to have a dramatic effect on the efficiency of fusion. a mixture of cellulysin and driselase led to a two-fold enhancemen ...	1987	24248839
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
chlorogenic acid biosynthesis: characterization of a light-induced microsomal 5-o-(4-coumaroyl)-d-quinate/shikimate 3'-hydroxylase from carrot (daucus carota l.) cell suspension cultures.	microsomal preparations from carrot (daucus carota l.) cell suspension cultures catalyze the formation of trans-5-o-caffeoyl-d-quinate (chlorogenate) from trans-5-o-(4-coumaroyl)-d-quinate. trans-5-o-(4-coumaroyl)shikimate is converted to about the same extent to trans-5-o-caffeoylshikimate. trans-4-o-(4-coumaroyl)-d-quinate, trans-3-o-(4-coumaroyl)-d-quinate, trans-4-coumarate, and cis-5-o-(4-coumaroyl)-d-quinate do not act as substrates. the reaction is strictly dependent on molecular oxygen a ...	1987	2821918
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
purification of an autocatalytic protein-glycosylating enzyme from cell suspensions of daucus carota l.	a glycosyltransferase was identified in the 174 000 · g membrane pellet and the supernatant from extracts of cell suspensions of daucus carota l. the enzyme from the supernatant was enriched 475-fold, and sodium dodecyl sulfate-gel electrophoresis and fluorography of this purified sample showed that the only enriched protein band (40 000 da) was simultaneously an enzyme and a glucose-acceptor. gel filtration and electrophoresis under non-denaturing conditions proved that in vivo this protein pro ...	1987	24225709
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
effects of methyl mercury on arrays of microtubules and macromolecular synthesis in daucus carota cultures.	cell suspension cultures of daucus carota were exposed to methyl mercury at concentrations between 0 and 6 micrograms/ml for 1, 3, or 24 hr. microtubule arrays exhibited no detectable disruption (as compared with controls) when treated with 1, 2, and 3 micrograms/ml methyl mercury. disorganization of microtubules did occur at higher concentrations (4-6 micrograms/ml) in a concentration/time-dependent manner. no recovery of microtubule arrays was evident when cells were placed in methyl mercury-f ...	1987	3428207
transient expression of electroporated dna in monocotyledonous and dicotyledonous species.	transient expression of electroporated dna was monitored in protoplasts of several monocot and dicot species by assaying for expression of chimeric chloramphenicol acetyltransferase (cat) gene constructions. expression was obtained in the dicot species of daucus carota, glycine max and petunia hybrida and the monocot species of triticum monococcum, pennisetum purpureum, panicum maximum, saccharum officinarum, and a double cross, trispecific hybrid between pennisetum purpureum, p. americanum, and ...	1987	24248756
developmental modulation of tubulin protein and mrna levels during somatic embryogenesis in cultured carrot cells.	the number of cortical microtubules (mts) increases considerably as cultured carrot (daucus carota l.) cells initiate and progress through somatic embryogenesis. the basis for this increase in mt number was investigated. a radioimmune assay was used to show that tubulin-protein per cell first decreased as the undifferentiated cells initiated embryonic development, but subsequently increased approximately fivefold between the globular and torpedo/plantlet stages. the increase during the torpedo/p ...	1987	24227436
thioredoxin and nadp-thioredoxin reductase from cultured carrot cells.	dark-grown carrot (daucus carota l.) tissue cultures were found to contain both protein components of the nadp/thioredoxin system-nadp-thioredoxin reductase and the thioredoxin characteristic of heterotrophic systems, thioredoxin h. thioredoxin h was purified to apparent homogeneity and, like typical bacterial counterparts, was a 12-kdalton (kda) acidic protein capable of activating chloroplast nadp-malate dehydrogenase (ec 1.1.1.82) more effectively than fructose-1,6-bisphosphatase (ec 3.1.3.11 ...	1987	24227431
an actin network is present in the cytoplasm throughout the cell cycle of carrot cells and associates with the dividing nucleus.	we have studied the f-actin network in cycling suspension culture cells of carrot (daucus carota l.) using rhodaminyl lysine phallotoxin (rlp). in addition to conventional fixation with formaldehyde, we have used two different nonfixation methods before adding rlp: extracting cells in a stabilizing buffer; inducing transient pores in the plasma membrane with pulses of direct current (electroporation). these alternative methods for introducing rlp revealed additional features of the actin network ...	1987	2440896
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
secretion and membrane recycling in plant cells: novel intermediary structures visualized in ultrarapidly frozen sycamore and carrot suspension-culture cells.	freeze-fracture electron microscopy of propane-jet-frozen samples has been employed to investigate vesicle-mediated secretion and membrane recycling events in carrot (daucus carota l.) and sycamore maple (acer pseudoplatanus l.) suspension-culture cells. stabilization of the cells by means of ultrarapid freezing has enabled us to preserve the cells in a turgid state and to visualize new intermediate membrane configurations related to these events. indeed, many of the observed membrane configurat ...	1987	24227269
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
methyl mercury toxicity in plant cultures: modification of resistance and demethylation by light and/or 2,4-dichlorophenoxyacetic acid.	cultures of daucus carota, ca-68-10, and lactuca sativa, le-67, were grown at increasing methyl mercury (mehg) concentrations ranging from initial doses of 0.05 to 5.0 micrograms/ml per day for 4 days with or without 0.15 microgram/ml 2,4-dichlorophenoxyacetic acid (2,4-d) in the presence or absence of light. the presence of 2,4-d interacted with light synergistically in the expression of mehg toxicity within the whole range of concentrations. demethylation patterns increased or decreased depend ...	1987	3595486
methotrexate and aminopterin effects on growth and regeneration in daucus carota.	daucus carota l., callus was cultured on various levels of the folate analogs, methotrexate (4-amino-10-methylfolic acid, amethopterin) and aminopter in (4-aminofolic acid). callus growth was inhibited as analog concentrations were increased from 0.01 μm to 10 μm. methotrexate concentrations in excess of 10 μm were lethal. in contrast, concentrations of aminopterin in the range of 10 to 100 μm resulted in renewed growth and somatic embryogenesis leading to plant regeneration. this plant regenera ...	1987	24248451
marker proteins for embryogenic differentiation patterns in pea callus.	polypeptide pattern alterations during somatic embryogenesis were investigated using callus cultures of two pisum sativum genotypes. both genotypes show the formation of two different callus lines from the same explant after six to eight weeks in culture: a nodular yellowish callus line, which forms somatic embryoids in suspension cultures (e(+)) and a white compact callus line with no regenerative capacity (e(-)). the cytosol proteins of the two different callus lines were separated in a semi-p ...	1987	24248449
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
the uptake of acylated anthocyanin into isolated vacuoles from a cell suspension culture of daucus carota.	anthocyanin-containing vacuoles were isolated from protoplasts of a cell suspension culture of daucus carota. the vacuoles were stable for at least 2 h as demonstrated by the fact that they showed no efflux of anthocyanin. the uptake of radioactively labelled anthocyanin was time-dependent with a ph optimum at 7.5, and could be inhibited by the protonophore carbonylcyanide m-chlorophenylhydrazone. furthermore, the transport was specific, since vacuoles from other plant species showed no uptake o ...	1987	24232844
thioredoxin and nadp-thioredoxin reductase from cultured carrot cells.	dark-grown carrot (daucus carota l.) tissue cultures were found to contain both protein components of the nadp/thioredoxin system--nadp-thioredoxin reductase and the thioredoxin characteristic of heterotrophic systems, thioredoxin h. thioredoxin h was purified to apparent homogeneity and, like typical bacterial counterparts, was a 12-kdalton (kda) acidic protein capable of activating chloroplast nadp-malate dehydrogenase (ec 1.1.1.82) more effectively than fructose-1,6-bisphosphatase (ec 3.1.3.1 ...	1987	11539727
effect of combining soil solarization with certain nematicides on target and nontarget organisms and plant growth.	field experiments compared pesticidal and plant growth effects of soil solarization, alone and in combination, with overall applications of several nematicides. nematodes, including meloidogyne incognita j2, that were targeted for control were significantly reduced (p < 0.05) by solarization, 1,3-dichloropropene (44 and 132 liter/ha), ethoprop (13.5 kg/ha), metham sodium (64 liter/ha), formaldehyde (111 liter/ha), and by solarization-nematicide combinations. control of pythium ultimum also was o ...	1987	19290287
transfer of resistance traits from carrot into tobacco by asymmetric somatic hybridization: regeneration of fertile plants.	transfer of methotrexate and 5-methyltryptophan resistance from carrot (daucus carota) to tobacco (nicotiana tabacum) was achieved by fusion between leaf mesophyll protoplasts of tobacco and irradiated cell culture protoplasts of carrot. some of the regenerated somatic hybrids exhibited normal tobacco morphology with coexpression and independent segregation of the transferred resistance markers. chromosomal instability resulted in aneuploid somatic hybrids with significantly lower chromosome num ...	1987	16593902
studies on the introduction and mobility of the maize activator element in arabidopsis thaliana and daucus carota.	we have co-transformed carrot (daucus carota) and arabidopsis thaliana with an agrobacterium tumefaciens non-tumorigenic t-dna carrying the maize transposable element activator (ac) and an agrobacterium rhizogenes ri t-dna. we present evidence that the ac element transposes in transformed root or root-derived callus cultures of both species. we show that fertile plants can be regenerated from transformed, root-derived callus cultures of arabidopsis, demonstrating the utility of the ri plasmid fo ...	1987	2832144
a parenchymatic medium solidifier for plant in vitro culture.	a new material for the solidification of liquid culture media was prepared from plant parenchyma tissues by mechanical subdivision, solute extration and dessication from ethanol. it is suitable for in vitro culture and propagation of callus as well as shoot tip cultures. the following plant materials have been grown by means of the new medium solidifier: shoot cultures of betula pendula roth, gerbera jamesonii h. bolus ex hook and floribunda rose "triumph", callus tissues of daucus carota l. and ...	1987	24248936
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
a rapid method for purification of organelles for dna isolation: self-generated percoll gradients.	self-generated percoll gradients have been used for rapid purification of crude chloroplasts and mitochondria, obtained by common differential centrifugation techniques. such purified organelles were used for isolating dna from safflower (carthamus tinctorius l.), carrot (daucus carota l.), various solanaceae, and numerous somatic hybrids. the method is simple, has the advantage of not requiring dnase, and is particularly well suited when only limited amounts of aseptically grown shoots are avai ...	1988	24241541
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
t-dna length variability in mannopine hairy root: more than 50 kilobasepairs of pri t-dna can integrate in plant cells.	independent carrot (daucus carota) hairy root lines were established by inoculation of discs taken from the same carrot with agrobacterium rhizogenes 8196 and a. tumefaciens c58c1(pri8196) carrying pri8196. several lines were compared with respect to t-dna length. one of them was found to have integrated sequences covering more than 50 kbp of the ri plasmid.	1988	24241540
effect of biologically active plants used as netst material and the derived benefit to starling nestlings.	the european starling sturnus vulgaris preferentially incorporates fresh sprigs of particular plant species for use as nesting material. chemicals found in these plants may act to reduce pathogen and ectoparasite populations normally found in nest environments. the present experiments were performed to test this nest protection hypothesis. in the fild, we experimentally determined that wild carrot daucus carota, a plant species preferred as nest material, effectively reduced the number of hemato ...	1988	28310369
a nuclear protein associated with cell divisions in plants.	a nuclear protein, present in carrot meristems and rapidly proliferating cultured cells of carrot (daucus carota l.) has been identified by the use of a monoclonal antibody (mab 21d7). by combining the techniques of two-dimensional polyacrylamide gel analysis and blotting separated proteins onto nitrocellulose sheets, it was shown that the antibody detected a single polypeptide of apparent molecular mass (m r) of 45000 and an isoelectric focusing point (pi) of 6.7. this protein was found by subc ...	1988	24221561
transfer of the cms trait in daucus carota l. by donor-recipient protoplast fusion.	x-irradiated protoplasts of daucus carota l., 28a1, carrying cytoplasmic male sterile (cms) cytoplasm and iodoacetamide-treated protoplasts of a fertile carrot cultivar, 'k5', were fused with polyethylene glycol (peg), and 73 plants were regenerated. twenty-six randomly chosen regenerated plants had non-parental mitochondrial dna (mtdna) as revealed by xbai restriction fragment patterns, and all of the plants investigated had diploid chromosome numbers. of the 11 cybrid plants that showed mtdna ...	1988	24232395
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
gene-expression programs in embryogenic and non-embryogenic carrot cultures.	somatic embryogenesis can be synchronized by enriching carrot (daucus carota l.) suspension cultures for small, dense clusters of cells termed proembryogenic masses (pems). gene-expression programs of pems were compared with those of embryonic and mature tissues by in-vitro translation of representative mrna populations and by nucleic-acid hybridization. analysis of invitro-translated polypeptides by two-dimensional polyacrylamide gel electrophoresis revealed striking similarities between the mr ...	1988	24220774
acquisition of embryogenic potential in carrot cell-suspension cultures.	embryogenic suspension cultures of domesticated carrot (daucus carota l.) are characterized by the presence of proembryogenic masses (pems) from which somatic embryos develop under conditions of low cell density in the absence of phytohormones. a culture system, referred to as starting cultures, was developed that allowed analysis of the emergence of pems in newly initiated hypocotyl-derived suspension cultures. embryogenic potential, reflected by the number of fems present, slowly increased in ...	1988	24220773
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
characterization of beta-fructosidase, an extracellular glycoprotein of carrot cells.	seedlings and suspension-cultured cells of carrot (daucus carota) contain a cell wall associated as well as a soluble form of beta-fructosidase (beta f). these two forms have different ph optima: 4.6 for cell wall beta f and 5.6 for soluble beta f. soluble beta f is relatively more abundant in the seedlings and cell wall beta f is relatively much more abundant in the cultured cells. protoplasts of cultured cells have only the soluble form (ph optimum 5.6) indicating that the cell wall associated ...	1988	3149517
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
purification of gp57, and auxin-regulated extracellular glycoprotein of carrots, and its immunocytochemical localization in dermal tissues.	a glycoprotein (gp57) was purified by ion-exchange and hydroxylapatite column chromatography from the 70%-ethanol precipitate of culture medium of non-embryogenic carrot cells (daucus carota l.) grown with 2,4-dichlorophen-oxyacetic acid (2,4-d). its apparent molecular mass (m r) was estimated to be 57000 by sodium dodecylsulfate-polyacrylamide gel electrophoresis and 50000 by gel filtration. gp57 contained 14% (w/w) carbohydrate; the m r of the peptide portion was estimated to be 55000 after de ...	1988	24221874
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
measurement of endogenous aba levels in chilled somatic embryos of carrot by immunoassay.	somatic embryos of carrot, daucus carota l. 'royal chantenay', were chilled at 4°c for the last 3 days of development in order to harden torpedo stage embryos to increase embryo survival during desiccation. aba levels in chilled and non-chilled embryos were measured using a polyclonal radioimmunoassay and a monoclonal enzyme-linked immunosorbent assay (elisa). the monoclonal elisa is the preferred technique due to superior sensitivity and specificity. aba levels, measured by either technique, we ...	1988	24241882
ionic basis of currents in somatic embryos of daucus carota.	a vibrating probe was used to measure extracellular electrical currents around developing somatic embryos in two lines (rcc27, rcc48) of cultured cells of daucus carota l. at the heart and torpedo stages. at ph 5.5, an inward current of 1.2±0.1 μa·cm(-2) (n=23) was detected at the cotyledon, and an outward current of 1.0±0.1 μa·cm(-2) (n=22) was found at the radicle in torpedostage embryos from the rcc27 line. at a ph of 5.75 the currents increased by 0.2-0.3 μa·cm(-2) (n=60-62). in a few cases ...	1988	24221723
daucus carota cells contain a dihydrofolate reductase: thymidylate synthase bifunctional polypeptide.	dihydrofolate reductase (dhfr) and thymidylate synthase (ts) activities from cell suspension cultures of daucus carota were shown to copurify on (nh4)2so4 fractionation, deae sephadex and methotrexate-sepharose affinity chromatography and to share approximately the same mr(183 kda and 185 kda respectively) as judged by gel filtration on sephacryl s-200.the copurified protein migrated as a single band on polyacrylamide gel electrophoresis under denaturing conditions.both activities could be elute ...	1988	24277564
antibody localization of extensin in cell walls of carrot storage roots.	the accumulation and cross-linking of hydroxyproline-rich glycoproteins (hrgps) in cell walls of dicotyledonous plants has been correlated with a number of wall-strengthening phenomena. polyclonal antibodies raised against glycosylated extensin-1, the most abundant hrgp in carrot (daucus carota l.) cell walls, recognize this antigen on gel and dot blots and on thin sections of epoxy-embedded carrot-root cell walls. since wall labeling can be largely reduced by preincubating the antibodies with p ...	1988	24221513
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
variation in endoplasmic-reticulum-associated glycoproteins of carrot cells cultured in vitro.	glycoproteins extracted from microsomes of in-vitro-cultured cells of daucus carota l. cv. us-harumakigosun were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and detected by peroxidase-conjugated concanavalin a. the appearance of a glycoprotein with mr 31 000 (gp 31) was correlated with the ability of cells to form somatic embryos. gp 31 appeared in embryogenic cells cultured in 2,4-dichlorophenoxyacetic acid (2,4-d)-containing medium, but not in somatic embryos and non- ...	1988	24226550
ethanol production and toxicity in suspension-cultured carrot cells and embryos.	the process of carrot (daucus carota l.) somatic embryogenesis is highly sensitive to exogenously added ethanol, since 5 mm ethanol inhibits this process by 50%, whereas the growth of proliferating carrot cells is inhibited to the same extent by 20 mm ethanol. this is consistent with the fact that proliferating cultures produce ethanol and release it into the medium at concentrations up to 20 mm, whereas embryogenic culture medium contains less than 1 mm ethanol. data are presented showing the i ...	1988	24226539
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
effects of nitrogen fertilizer and weed control on nutritive quality of carrots (daucus carota l.).	the nutritive quality of carrots, obtained from different herbicide-treated plots and under different levels of nitrogen application ranging from zero to 80 kg nitrogen/ha, was compared. there were significant differences in carotene content, t.s.s. (total soluble solids) and organoleptic characteristics under the influence of different treatments. the maximum carotene content, t.s.s. and organoleptic characteristics were observed with the application of 80 kg. nitrogen/ha and fluchloralin herbi ...	1988	2852805
identification of a wound-induced inhibitor of a nuclear factor that binds the carrot extensin gene.	following wounding of carrot (daucus carota l.) roots, the activity of a nuclear factor (egbf-1) that binds a 5'-region of the carrot extensin gene declines to undetectable levels within 48 h. mixing of nuclear extracts from wounded roots with nuclear extracts from unwounded roots has demonstrated the existence of a wound-induced inhibitor of egbf-1. inhibition of egbf-1 dna-binding activity by nuclear extracts from wounded roots is shown to be specific for egbf-1, and to be destroyed by heat tr ...	1989	24201846
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
effect of exogenous amino acids on the intracellular content of proline and other amino acids in daucus carota cells.	the effect of tryptophan on the biosynthesis of proline has been investigated. cells of daucus carota grown in b5 medium supplemented with 5×10(-4)m tryptophan acquired the ability to grow in the presence of inhibitory concentrations of azetidine-2-carboxylic acid, an analog of proline. when trp was added to carrot cell cultures at sub-growth inhibiting concentrations, overproduction of intracellular free proline was observed. an increase was also observed for lys, his, ala, leu and phe. likewis ...	1989	24233368
induction of chalcone synthase in cell suspension cultures of carrot (daucus carota l. spp. sativus) by ultraviolet light: evidence for two different forms of chalcone synthase.	two cell lines of carrot (daucus carota l. spp. sativus), grown as cell-suspension cultures in the dark, were irradiated with ultraviolet light (315-420 nm) 10 d after the onset of cultivation. chalcone synthase (chs) enzyme activity was induced in both cell lines. anthocyanin synthesis was only stimulated in the anthocyanin-containing cell line dcb. parallel to the increase in chs activity there was an increase with time in the amount of one chs form with an isoelectric point of 6.5 and a molec ...	1989	24201661
structural analysis of the cell walls regenerated by carrot protoplasts.	a procedure was developed to isolate protoplasts rapidly from carrot (daucus carota l. cv. danvers) cells in liquid culture. high purity of cell-wall-degrading enzymes and ease of isolation each contributed to maintenance of viability and initiation of regeneration of the cell wall by a great majority of the protoplasts. we used this system to re-evaluate the chemical structure and physical properties of the incipient cell wall. contrary to other reports, callose, a (1 → 3)β-d-glucan whose synth ...	1989	24201658
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
site-specific binding of a nuclear factor to the carrot extensin gene is influenced by both ethylene and wounding.	experiments conducted in vitro using the electrophoretic mobility shift assay have shown that a single region of the extensin gene of carrot (daucus carota l.) interacts with a protein factor designated extensin gene binding factor-1 (egbf-1) present in nuclear extracts obtained from carrot roots. this interaction is sequence-specific as judged by the failure of other plant gene sequences to compete with the extensin gene for egbf-1 binding. the egbf-1 activity is organspecific, not being expres ...	1989	24201417
reconstitution of intermediate filaments from a higher plant.	immunological studies have shown that plants contain intermediate-filament antigens, but it is not known whether these proteins are capable in themselves of forming filaments. to address this problem, a detergent-resistant and high-salt-insoluble fraction from carrot (daucus carota l.) suspension cells was solubilized with 9 m-urea and then subjected to a two-step dialysis procedure, devised for the reconstitution of animal intermediate filaments. this induced the self-assembly of 10 nm filament ...	1989	2775240
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
molecular and genetic analysis of an embryonic gene, dc 8, from daucus carota l.	to understand the morphogenetic and physiological processes occurring during plant embryogenesis, we isolated cdna clones homologous to genes preferentially expressed during somatic embryogenesis. one of these cdna clones detected an embryo-specific mrna species with a corresponding protein of 66 kda. the expression pattern of the mrna is similar between somatic and zygotic embryos of carrots. to characterize the gene encoding this mrna, we isolated the corresponding genomic clones. molecular an ...	1989	2571069
evidence of an auxin-mediated phosphoinositide turnover and an inositol (1,4,5)trisphosphate effect on isolated membranes of daucus carota l.	microsomal membranes from carrot suspension cells were phosphorylated in vitro with [gamma-32p]atp. in the presence of submicromolar concentrations of the natural auxin indoleacetic acid (iaa), a rapid, but transient decrease of the [32p] label could be detected in the phospholipid extracts of the membranes. the phytohormone effect was not the result of an inhibition of the lipid phosphorylation reactions, but was caused by a simultaneous release of water-soluble compounds, which, according to t ...	1989	2550489
carrot (daucus carota) hypocotyl transformation usingagrobacterium tumefaciens.	daucus carota hypocotyl sections were transformed withagrobacterium tumefaciens lba4404 containing camv 35s promoter, β-glucuronidase coding sequence and the nopaline synthase (nos) poly adenylation sequences in bin 19. sliced sterile seedling hypocotyl segments were preincubated for 2 days, co-cultivated withagrobacterium for an additional 2 days, and then transferred to medium containing 100ug/ml of kanamycin and 400ug/ml carbenicillin. in 6 weeks kanamycin resistant calli were obtained in 5.8 ...	1989	24233274
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
analysis of chloroplast and mitochondrial dnas in asymmetric somatic hybrids between tobacco and carrot.	chloroplast and mitochondrial dnas have been examined by comparison of restriction enzyme patterns in asymmetric hybrid plants, resulting from the fusion between leaf mesophyll protoplasts of nicotiana tabacum (solanaceae), and irradiated cell culture protoplasts of daucus carota (umbellifereae). these somatic hybrids with normal tobacco morphology were selected as a consequence of the transfer of methotrexate and 5-methyltryptophan resistance from carrot to tobacco. the restriction patterns of ...	1989	24232795
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
a family of abundant plasma membrane-associated glycoproteins related to the arabinogalactan proteins is unique to flowering plants.	we have identified a family of abundant peripheral plasma membrane glycoproteins that is unique to flowering plants. they are identified by a monoclonal antibody, mac 207, that recognizes an epitope containing l-arabinose and d-glucuronic acid. immunofluorescence and immunogold labeling studies locate the mac 207 epitope to the outer surface of the plasma membrane both in protoplasts and in intact tissues. in some cells mac 207 also binds to the vacuolar membrane, probably reflecting the movemen ...	1989	2469683
stimulation ofdaucus carota somatic embryogenesis by inhibitors of ethylene synthesis: cobalt and nickel.	the effects of co(2+) and ni(2+) on ethylene production and somatic embryogenesis by carrot (daucus carota l.) cell cultures were studied. at concentrations of 10 μm to 50 μm, cocl2 effectively inhibited ethylene production by embryogenic cultures and significantly stimulated somatic embryogenesis. the observed increase of embryo number was proportional to the inhibition level of ethylene production. however, cocl2 had no effect when ethephon was supplied. nickel also reduced ethylene production ...	1989	24233099
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
microtubule-binding proteins from carrot : i. initial characterization and microtubule bundling.	microtubules (mts) participate in several processes of fundamental importance to growth and development in higher plants, yet little is known about the proteins with which they associate. information about these molecules is important because they probably play a role in mediating functional and structural differences between various mt arrays. as a first step in gaining insight into this problem, we have isolated, from suspension-cultured cells of carrot (daucus carota l.), non-tubulin proteins ...	1989	24212347
mitochondrial genome diversity among cultivars of daucus carota (ssp. sativus) and their wild relatives.	restriction fragment patterns of mitochondrial dnas (mtdnas) from 13 carrot cultivars (daucus carota ssp. sativus), wild carrot (ssp. carota), ssp. gummifer, and d. capillifolius were compared with each other using four restriction endonucleases. the mtdnas of the 13 carrot cultivars could be classified into three distinct types - i, ii and iii - and were also clearly distinguishable from the mtdnas of wild carrot (type iv), gummifer (v) and d. capillifolius (vi). the proportions of common restr ...	1989	24232471
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
release of somatic embryogenic potential from excised zygotic embryos of carrot and maintenance of proembryonic cultures in hormone-free medium.	excised zygotic embryos, mericarps ("seeds") and hypocotyls of seedlings of cultivated carrot daucus carota cv. scarlet nantes were evaluated for their ability to generate somatic embryos on a semisolid hormone-free nutrient medium. neither intact zygotic embryos nor hypocotyls ever produced somatic embryos. however, mericarps and broken zygotic embryos were excellent sources for somatic embryo production (response levels as high as 86%). somatic embryo formation was highest from cotyledons, but ...	1989	11540921
a qualitative and quantitative assay of dihydrofolate reductase in carrot cells resistant to methotrexate.	the cytochemical pattern and the quantitative assay of dhfr on daucus carota cell lines sensitive and resistant to methotrexate (mtx) are described. cytoplasmatic enzyme activity is evidenced as granules of formazan, final reaction product, in the majority of the cells. dhfr activity appears low in daucus carota cells used as control while in carrot cells resistant to mtx is very high, an observation which parallels previous biochemical studies. these results are supported by quantitative data o ...	1989	2757603
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
growth effects, uptake and metabolism of trifluralin in tissue cultures.	growth effects, uptake and metabolism of trifluralin (alpha, alpha, alpha-trifluoro-2,6-dinitro-n,n-dipropyl-p-toluidine) in carrot (daucus carota l.) and tobacco (nicotiana tabaccum l.) callus tissue were determined. carrot callus was initiated from tap root tissue on murashige and skoog medium with kinetin and 2,4-dichlorophenoxy acetic acid (2,4-d). tobacco callus was initiated from pith tissue on murashige and skoog medium with indole-3-acetic acid (iaa) and kinetin.	1989	2809078
structure and function of the promoter of the carrot v-type h(+)-atpase catalytic subunit gene.	we investigated the 5'-upstream region of the gene encoding the catalytic subunit of the v-type h(+)-atpase in daucus carota. a genomic sublibrary was screened with a cdna probe, and a 4-kilobase genomic clone was obtained covering the first two exons and about 3 kilobases of the 5'-upstream sequence. the intron/exon boundaries matched established consensus sequences. within 240 base pairs (bp) upstream of the initiation codon three putative tata boxes were found. ribonuclease protection and pri ...	1990	2139875
purification and characterization of cytosolic aldolase from carrot storage root.	a single fructose-1,6-bisphosphate (fbp) aldolase has been detected in extracts from carrot storage roots (daucus carota l.). the enzyme was purified 850-fold to electrophoretic homogeneity and a final specific activity of 26.3 mumols of fbp utilized/min per mg of protein. sds/page of the final preparation revealed a single protein-staining band of 40 kda. the native molecular mass was determined by analytical gel filtration to be 159 kda, indicating that the enzyme is a homotetramer. denaturing ...	1990	2198022
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 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
purification and some properties of a daucus carota lectin which enhances the activation of prophenoloxidase by cacl(2).	carrot (daucus carota) cell cultures were found to secrete a protein, with the molecular weight of 58,000, which could strongly enhance the activation of carrot prophenoloxidase by cacl(2). the protein was isolated from the culture filtrate and purified to electrophoretic homogeneity. the purified protein did also show hemagglutinating activity toward rat as well as rabbit erythrocytes and this activity was inhibitied by n-acetylglucosamine or fetuin.	1990	16667519
growth of carrot and tomato from oxamyl-coated seed and control of meloidogyne hapla.	oxamyl was coated on carrot (daucus carota l. cv. spartan fancy-80) and tomato (lycopersicon esculentum mill. cv. glamour) seeds with a polymer sticker for the control of meloidogyne hapla. the sticker diluted in water 1:1 delayed carrot seedling emergence. oxamyl at 40 mg/ml in a 1:5 dilution of sticker lowered the rate of carrot seedling emergence until day 13 and plant growth until day 28. oxamyl at 20 or 40 mg/ml in a 1:5 dilution of sticker on carrot seeds planted in m. hapla-infested muck ...	1990	19287706
pinwheel inclusions in morphogenesis: a possible alternative to induction by viruses.	pinwheel inclusions (pws) were found in cells of callus tissue derived from explants of secondary phloem parenchyma of carrot (daucus carota) storage root and grown on a basal medium containing zeatin and indoleacetic acid or coconut milk, naphthalene acetic acid, or combinations of these. preliminary attempts to demonstrate the presence of viruses in the callus tissue failed. the possibility that the tissles were infected by a low titer or unstable conventional virus or by a defective mutant ha ...	1990	184764
pectin esterification is spatially regulated both within cell walls and between developing tissues of root apices.	monoclonal antibodies recognizing un-esterified (jim5) and methyl-esterified (jim7) epitopes of pectin have been used to locate these epitopes by indirect immunofluorescence and immunogold electron microscopy in the root apex of carrot (daucus carota l.). both antibodies labelled the walls of cells in all tissues of the developing root apex. immunogold labelling observed at the level of the electron microscope indicated differential location of the pectin epitopes within the cell walls. the un-e ...	1990	24196931
short-term treatment with cell wall degrading enzymes increases the activity of the inositol phospholipid kinases and the vanadate-sensitive atpase of carrot cells.	treating carrot (daucus carota l.) suspension culture cells with a mixture of cell wall degrading enzymes, driselase, resulted in an increase in the percentage of [(3)h]phosphatidylinositol bisphosphate. analysis of the lipid kinase activities in the isolated plasma membranes after whole cell treatment indicated that treatment with driselase (2% weight/volume; the equivalent of 340 units per milliliter of hemicellulase and 400 units per milliliter of cellulase activity) or treatment with hemicel ...	1990	16667922
somatic embryogenesis of carrot in hormone-free medium: external ph control over morphogenesis.	cultures of preglobular stage proembryos (pgsps) were initiated from mechanically wounded mature zygotic embryos of carrot, daucus carota, on a hormone-free, semisolid medium. these pgsps have been maintained and multiplied for extended periods without their progression into later embryo stages on the same hormone-free medium containing 1 mm nh4+ as the sole nitrogen source. sustained maintenance of cultures comprised exclusively of pgsps was dependent on medium ph throughout the culture period. ...	1990	11541515
abscisic acid regulation of dc8, a carrot embryonic gene.	dc8 encodes a hydrophylic 66 kilodalton protein located in the cytoplasm and cell walls of carrot (daucus carota) embryo and endosperm. during somatic embryogenesis, the levels of dc8 mrna and protein begin to increase 5 days after removal of auxin. to study the role of abscisic acid (aba) in the regulation of dc8 gene, fluridone, 1-methyl-3-phenyl,-5(3-trifluoro-methyl-phenyl)-4(1h)-pyridinone, was used to inhibit the endogenous aba content of the embryos. fluridone, 50 micrograms per millilite ...	1990	16667766
influence of a specific xyloglucan-nonasaccharide derived from cell walls of suspension-cultured cells of daucus carota l. on regenerating carrot protoplasts.	a xyloglucan oligosaccharide was isolated from cell walls of daucus carota l. suspension-cultured cells. from analytical data (gel-permeation chromatography, thin-layer chromatography, monosaccharide analysis, methylation analysis) it can be concluded that this oligosaccharide preparation consists mainly of a nonasaccharide known as xg9 (glc4xyl3galfuc). this nonasaccharide showed excellent "anti-auxin" properties in the pea-stem bioassay, with 80% inhibition of 2,4-dichlorophenoxyacetic acid (2 ...	1990	24197092
the s-methylmethionine cycle in lemna paucicostata.	the metabolism of s-methylmethionine has been studied in cultures of plants of lemna paucicostata and of cells of carrot (daucus carota) and soybean (glycine max). in each system, radiolabeled s-methylmethionine was rapidly formed from labeled l-methionine, consistent with the action of s-adenosyl-l-methionine:methionine s-methyltransferase, an enzyme which was demonstrated during these studies in lemna homogenates. in lemna plants and carrot cells radiolabel disappeared rapidly from s-methylmet ...	1990	16667513
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
embryogenic and non-embryogenic cell lines of daucus carota cloned from meristematic cell clusters: relation with cell ploidy determined by flow cytometry.	the presence of totipotent and non-totipotent cells in embryogenic carrot cell suspension cultures was examined by cloning of cell microclusters. forty clones were isolated and the distribution of their embryogenic potential was studied. nonembryogenic, weakly and highly embryogenic cell lines were selected. after one year of subculture a second cloning round showed that the highly embryogenic and the non-embryogenic cell lines were homogenous and stable. a measurement of ploidy levels of clones ...	1990	24232682
patterns of expression of the jim4 arabinogalactan-protein epitope in cell cultures and during somatic embryogenesis in daucus carota l.	spatiotemporal patterns of expression of the cell-surface arabinogalactan-protein epitope defined by monoclonal antibody jim4 (j.p. knox et al., 1989, development 106, 47-56) have been characterized by indirect immunofluorescence during the process of somatic embryogenesis in daucus carota l. the jim 4 epitope (j4e) occurred on cells established in culture from hypocotyl explants which appeared to derive, at least in part, from the epidermal cells of the hypocotyl. cultures maintained in the pre ...	1990	24201958
low external ph replaces 2,4-d in maintaining and multiplying 2,4-d-initiated embryogenic cells of carrot.	a mixed culture comprised of both embryonic globules and nonembryogenic callus was derived from seedling hypocotyls of daucus carota cv. scarlet nantes on 2,4-d- containing medium using well-established methods. then the mixed cultures were transferred to, and serially subcultured on, a hormone-free medium near ph 4. the medium contained 1 mm nh4+ as the sole nitrogen source. when cultured in this way, embryonic globules were able to multiply without development into later embryo stages. nonembr ...	1990	11537852