Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| molecular diversity at the major cluster of disease resistance genes in cultivated and wild lactuca spp. | diversity was analyzed in wild and cultivated lactuca germplasm using molecular markers derived from resistance genes of the nbs-lrr type. three molecular markers, one microsatellite marker and two scar markers that amplified lrr-encoding regions, were developed from sequences of resistance gene homologs at the main resistance gene cluster in lettuce. variation for these markers were assessed in germplasm including accessions of cultivated lettuce, lactuca sativa l. and three wild lactuca spp., ... | 1999 | 22665172 |
| retention of microcystis aeruginosa and microcystin by salad lettuce (lactuca sativa) after spray irrigation with water containing cyanobacteria. | colonies and single cells of microcystis aeruginosa and the hepatotoxin microcystin were retained by salad lettuce after growth with spray irrigation water containing the microcystin-producing cyanobacteria. these findings are discussed in terms of crop spray irrigation with water containing cyanobacteria and potential human exposure to cyanobacterial toxins via plant foods grown in such circumstances. | 1999 | 10400301 |
| [the enteroparasitic contamination of commercial vegetables in the cities of niterói and rio de janeiro, brazil]. | the aim of this study was to evaluate the parasitological contamination of vegetables to be consumed raw and commercialized in niterói and rio de janeiro cities. we studied 128 samples of vegetables--lettuce (lactuca sativa) and watercress (nasturtium officinale)--from supermarkets, greengrocer shops and self-service restaurants. only 6.2% of the samples were positive for parasitic structures with morphological aspects similar to those of animal parasites. we detected acarids, acarid eggs, insec ... | 1999 | 10495664 |
| a plant-derived edible vaccine against hepatitis b virus. | the infectious hepatitis b virus represents 42 nm spherical double-shelled particles. however, analysis of blood from hepatitis b virus carriers revealed the presence of smaller 22 nm particles consisting of a viral envelope surface protein. these particles are highly immunogenic and have been used in the design of hepatitis b virus vaccine produced in yeast. upon expression in yeast, these proteins form virus-like particles that are used for parenteral immunization. therefore, the dna fragment ... | 1999 | 10506582 |
| increased stable inheritance of herbicide resistance in transgenic lettuce carrying a pete promoter-bar gene compared with a camv 35s-bar gene. | inheritance of resistance to herbicide (300 mg/l glufosinate ammonium) up to the third (t3) seed generation was compared in two populations of transgenic lettuce (lactuca sativa l. cv 'evola') harbouring a t-dna containing the bar gene, linked to either the cauliflower mosaic virus (camv) 35s promoter, or a -784-bp plastocyanin promoter from pea (pete). only 2.5% (4/163) of camv 35s-bar plants, selected by their kanamycin resistance(t0 generation), transmitted herbicide resistance at high freque ... | 1999 | 22665193 |
| survey of crop losses in response to phytoparasitic nematodes in the united states for 1994. | previous reports of crop losses to plant-parasitic nematodes have relied on published results of survey data based on certain commodities, including tobacco, peanuts, cotton, and soybean. reports on crop-loss assessment by land-grant universities and many commodity groups generally are no longer available, with the exception of the university of georgia, the beltwide cotton conference, and selected groups concerned with soybean. the society of nematologists extension committee contacted extensio ... | 1999 | 19270925 |
| suppression of meloidogyne hapla and its damage to lettuce grown in a mineral soil amended with chitin and biocontrol organisms. | chitin was used as soil amendment in fiberglass field microplots, alone or with one or a combination of two to three species of hirsutella rhossiliensis, paecilomyces marquandii, verticillium chlamydosporium, bacillus thuringiensis, and streptomyces costaricanus. sudangrass and rapeseed were planted as cover crops and incorporated into soil as green manure amendments. chitin amendment alone increased the marketable yield of lettuce in 1995 and reduced root-galling ratings and the reproduction of ... | 1999 | 19270942 |
| microsatellite retrieval in lettuce (lactuca sativa l.). | by using enriched genomic libraries, microsatellite-containing sequences were isolated from lettuce (lactuca sativa) with high efficiency. with this approach, a sizeable fraction (up to 55%) of the clones contained a microsatellite. in about half of these clones, primers could be designed for pcr amplification of the microsatellite. this yielded 28 primer sets amplifying unambiguously scorable products, of which 26 showed polymorphisms in a test set of six lettuce varieties. practically all micr ... | 1999 | 10208007 |
| efficacy of bacillus thuringiensis, paecilomyces marquandii,and streptomyces costaricanus with and without organic amendments against meloidogyne hapla infecting lettuce. | chitin, wheat mash, or brewery compost were incorporated into unfumigated and methyl bromide-fumigated organic soils placed in microplots formed from cylindrical drainage tiles (0.25 m-diam. clay tile). after 3 weeks, meloidogyne hapla and cell or spore suspensions of bacillus thuringiensis, paecilomyces marquandii, and streptomyces costaricanus were individually added to the soils of designated microplots. a b. thuringiensis + s. costaricanus combination was also tested. lettuce seedlings, cv. ... | 2000 | 19270951 |
| hirsutella rhossiliensisand verticillium chlamydosporium as biocontrol agents of the root-knot nematode meloidogyne hapla on lettuce. | hirsutella rhossiliensis and verticillium chlamydosporium infected second-stage juveniles (j2) and eggs of meloidogyne hapla, respectively, in petri dishes and in organic soil in pots planted to lettuce in the greenhouse. in vitro, h. rhossiliensis produced 78 to 124 spores/infected j2 of m. hapla. the number of j2 in roots of lettuce seedlings decreased exponentially with increasing numbers of vegetative colonies of h. rhossiliensis in the soil. at an infestation of 8 m. hapla eggs/cm(3) soil, ... | 2000 | 19270953 |
| identification of multi-gene families encoding isopentenyl diphosphate isomerase in plants by heterologous complementation in escherichia coli. | two cdnas encoding isopentenyl diphosphate isomerase (ipi) in adonis aestivalis, arabidopsis thaliana, and lactuca sativa, and single examples from oryza sativa and tagetes erecta were identified. an analysis of these and other ipi leads us to suggest a separate origin for green algal and plant genes and propose that a single gene encodes plastid and cytosolic ipi in plants. | 2000 | 10750717 |
| impact of insecticides and surfactant on lettuce physiology and yield. | insecticides are used extensively on lettuce, lactuca sativa l., grown in southwestern arizona because of heavy insect pressure that can potentially reduce lettuce productivity. multiple sprays are made per season to manage these insects in lettuce. one of the major concerns related to extensive insecticide applications in lettuce is the potential subtle impact of insecticides that may reduce lettuce photosynthesis and yield. we conducted field and greenhouse experiments to examine the impact of ... | 2000 | 10902331 |
| growth promoting effect of two sinorhizobium meliloti strains (a wild type and its genetically modified derivative) on a non-legume plant species in specific interaction with two arbuscular mycorrhizal fungi. | in the present study, we have investigated whether the ubiquitous rhizosphere soil organism sinorhizobium meliloti has a plant growth promoting (pgp) effect on non-leguminous plant species. such pgp activity was investigated for both a wild type strain and its genetically modified (gm) derivative, which had an enhanced biofertilizer capability. the pgp effect of these rhizobial strains was tested in interaction with two arbuscular-mycorrhizal (am) fungi: g. mosseae or g. intraradices on lettuce ... | 2000 | 11011093 |
| a comparison of peronospora parasitica (downy mildew) isolates from arabidopsis thaliana and brassica oleracea using amplified fragment length polymorphism and internal transcribed spacer 1 sequence analyses. | amplified fragment length polymorphism (aflp) fingerprints and internal transcribed spacer 1 (its1) sequences from 27 peronospora parasitica isolates (collected from arabidopsis thaliana or brassica oleracea), 5 albugo candida isolates (from the same hosts and from capsella bursa-pastoris), and 1 bremia lactucae isolate (from lactuca sativa) were compared. the aflp analysis divided the isolates into five groups that correlated with taxonomic species and, in most cases, with host origin. the only ... | 2000 | 11017765 |
| quantification of metal bioavailability for lettuce (lactuca sativa l.) in field soils. | understanding metal bioavailability of plants in soils requires, apart from physiological processes and symbiosis with arbuscular mycorrhizal fungi, the consideration of the chemical availability in the soil solution (the intensity of the toxic exposure) and the soil's capacity to supply the metal (capacity). in this contribution we report on the time-dependent accumulation of as, cd, cr, cu, ni, pb, and zn in lettuce (lactuca sativa l.). bioassays with 17 dutch field soils and two artificially ... | 2000 | 11031301 |
| cantaloupe melon peroxidase: characterization and effects of additives on activity. | peroxidase in cantaloupe melon (cucumis melo l. var. reticulatus naud.), a fruit commonly fresh cut processed, was characterized to determine reaction pathway, optimal conditions for activity and effect of some additives on enzymatic action. mn2+, cacl2, nano2 and kinetin had partial inhibitory effects on enzyme activity. activity was effectively inhibited by compounds capable of chelating peroxidase heme iron such as diethyldithiocarbamate and tiron, but unaffected by edta. free radical scaveng ... | 2000 | 10907237 |
| metabolite profiling of sesquiterpene lactones from lactuca species. major latex components are novel oxalate and sulfate conjugates of lactucin and its derivatives. | wounding leaves or stems of lactuca species releases a milky latex onto the plant surface. we have examined the constituents of latex from lactuca sativa (lettuce) cv. diana. the major components were shown to be novel 15-oxalyl and 8-sulfate conjugates of the guaianolide sesquiterpene lactones, lactucin, deoxylactucin, and lactucopicrin. the oxalates were unstable, reverting to the parent sesquiterpene lactone on hydrolysis. oxalyl derivatives have been reported rarely from natural sources. the ... | 2000 | 10858433 |
| classical and biochemical endpoints in the evaluation of phytotoxic effects caused by the herbicide trichloroacetate. | three terrestrial plant species, oat (avena sativa ), chinese cabbage (brassica campestris cv. chinensis) and lettuce (lactuca sativa), were exposed to different concentrations of herbicide tca (sodium trichloroacetate) in a growth test according to guideline oecd # 208. classical (i.e. germination and biomass) and biochemical (i.e., antioxydant enzyme activities) endpoints were investigated. germination rate decreased significantly at 3.9 mg tca kg dry soil(-1) (for oat and lettuce) and 62.5 mg ... | 2000 | 11064042 |
| natural and synthetic podolactones with potential use as natural herbicide models. | a collection of 11 natural and synthetic podolactones have been tested as allelochemicals in a range between 10(-4) and 10(-9) m, and their potential use as natural herbicide models is discussed. their effects on the germination and growth of the dicots lactuca sativa (cv. nigra and cv. roman), lepidium sativum, and lycopersicon esculentum and the monocots allium cepa, hordeum vulgare, and triticum aestivum as standard target species have been studied. an important inhibitory effect on the germi ... | 2000 | 10898656 |
| effect of sludge-processing mode, soil texture and soil ph on metal mobility in undisturbed soil columns under accelerated loading. | the effect of sludge processing (digested dewatered, pelletized, alkaline-stabilized, composted, and incinerated), soil type and initial soil ph on trace metal mobility was examined using undisturbed soil columns. soils tested were hudson silt loam (glossaquic hapludalf) and arkport fine sandy loam (lamellic hapludalf), at initial ph levels of 5 and 7. sludges were applied during four accelerated cropping cycles (215 tons/ha cumulative application for dewatered sludge; equivalent rates for other ... | 2000 | 15092904 |
| nitric oxide stimulates seed germination and de-etiolation, and inhibits hypocotyl elongation, three light-inducible responses in plants. | seed germination, greening of etiolated plants and inhibition of hypocotyl elongation are stimulated by light, which is sensed by various types of photoreceptor. nitric oxide (no) has proven to be a bioactive molecule, especially in mammalian cells and, most recently, in plants. like some phytochrome-dependent processes, many no-mediated ones are accomplished through increases in cgmp levels. given these similarities, we proposed that no could take part in light-mediated events in plants. here w ... | 2000 | 10664127 |
| abscisic acid and hypoxic induction of anoxia tolerance in roots of lettuce seedlings. | lettuce (lactuca sativa l.) seedlings were subjected to anoxic stress after aba-pretreatment (aba-pt) or hypoxic-pretreatment (h-pt). the h-pt increased the survivability of the anoxia in roots of the seedlings by 5.2-fold compared to that of non-pretreated (n-pt) seedlings. aba-pt also increased the survivability at concentrations greater than 1 microm, and the survivability increased with increasing aba doses. at 100 microm aba, the survivability was 4.5-fold greater than that of n-pt seedling ... | 2000 | 11113172 |
| the action spectrum for maximal photosensitivity of germination. | fruits of garden lettuce, imbibed in 0.01 m kno3, were depleted of maternal active phytochrome b by saturating deep-red exposure and photosensitized by chilling for 1 week at 4 degrees c. twenty saturated fluence-response curves for photoinduced germination were elaborated between 300 and 800 nm, using exposure periods from 6 to 600 s at 22.5 degrees c; there is linear and closely parallel regression in the logarithmic probability net. the reciprocals of the half-response fluences obtained gave ... | 2000 | 11091963 |
| inactivation of dna replication origins by the cell cycle regulator, trigonelline, in root meristems of lactuca sativa. | the effects of trigonelline (trg) on the cell cycle in root meristems of lactuca sativa l. were examined in the knowledge that trg is a cell cycle regulator that causes cell arrest in g2, and prevents ligation of replicons in s-phase. the hypothesis was tested that continuous exposure to trg would perturb dna replication which, in turn, would lengthen the cell cycle and impair root elongation. using dna fibre autoradiography, mean replicon size was 31 and 13 microm in the trg (3 mm) and control ... | 2000 | 10923713 |
| inhibition of plant asparagine synthetase by monoterpene cineoles. | asparagine (asn) synthetase (as) is the key enzyme in asn biosynthesis and plays an important role in nitrogen mobilization. despite its important physiological function, little research has been done documenting inhibitors of plant as. plant growth inhibition caused by the natural monoterpene 1,4-cineole and its structurally related herbicide cinmethylin was reversed 65% and 55%, respectively, by providing 100 microm asn exogenously. reversion of the phytotoxic effect was dependent on the conce ... | 2000 | 10859202 |
| halogenated auxins affect microtubules and root elongation in lactuca sativa. | we studied the effect of 4,4,4-trifluoro-3-(indole-3-)butyric acid (tfiba), a recently described root growth stimulator, and 5,6-dichloro-indole-3-acetic acid (dciaa) on growth and microtubule (mt) organization in roots of lactuca sativa l. dciaa and indole-3-butyric acid (iba) inhibited root elongation and depolymerized mts in the cortex of the elongation zone, inhibited the elongation of stele cells, and promoted xylem maturation. both auxins caused the plane of cell division to shift from ant ... | 2000 | 11762379 |
| calcium localization and tipburn development in lettuce leaves during early enlargement. | tissue concentrations of ca, mg, and k were determined across immature leaves of lettuce (lactuca sativa l. 'buttercrunch') at different stages of enlargement using electron microprobe x-ray analysis. the analysis was with a wavelength dispersive spectrometer to permit detection of low concentrations of ca. patterns of mineral accumulation in immature leaves that were exposed were compared to patterns of accumulation in leaves that were enclosed within a developing head. the leaves developing wi ... | 2000 | 11543566 |
| improving spinach, radish, and lettuce growth under red light-emitting diodes (leds) with blue light supplementation. | radish (raphanus sativus l. cv. cherriette), lettuce (lactuca sativa l. cv. waldmann's green), and spinach (spinacea oleracea l. cv. nordic iv) plants were grown under 660-nm red light-emitting diodes (leds) and were compared at equal photosynthetic photon flux (ppf) with either plants grown under cool-white fluorescent lamps (cwf) or red leds supplemented with 10% (30 micromoles m-2 s-1) blue light (400-500 nm) from blue fluorescent (bf) lamps. at 21 days after planting (dap), leaf photosynthet ... | 2001 | 12542027 |
| hysteresis and positive cooperativity of iceberg lettuce polyphenol oxidase. | a kinetic study of the diphenolase activity of latent polyphenol oxidase (ppo), purified from iceberg lettuce (lactuca sativa l), revealed a sigmoid relationship between the reaction rate and the substrate concentration with a high hill coefficient (n(h) = 3.8). this positive cooperativity had not been previously described for any ppo. furthermore, the enzyme showed a lag phase in the expression of this activity, suggesting a hysteretic nature of the enzyme. the kinetic behavior, the latency and ... | 2001 | 11726215 |
| lyc1, a transgenic mutant of lactuca sativa (lettuce) tightly linked to chloroplast biogenesis. | a t-dna tagging mutant of lettuce was studied. the transgenic lettuce mutant, designated light yellowish cotyledon1 (lyc1), exhibited a chloroplast mutant phenotype in which the chloroplast development was arrested at the cotyledon stage and the cotyledon became a light yellowish due to the reduced level of chlorophyll content. a microscopic observation of the mutant showed that the chloroplasts failed to position along the cell wall, but were scattered in the cytoplasm. the number of chloroplas ... | 2001 | 11710531 |
| prediction of uptake of copper from solution by lettuce (lactuca sativa romance). | we studied effects of free copper ion activity and total copper concentration on copper uptake by lettuce from nutrient solution and a model was developed. in ethylenediaminetetraacetic acid and dissolved organic matter treatments, when ph and free copper ion activity were the same, root copper concentration did not change with the total copper concentration. however, at fixed ph and total copper concentration, root copper concentration increased with, and was log-log linearly related to free co ... | 2001 | 11699781 |
| evidence for a tetrameric form of iceberg lettuce (lactuca sativa l.) polyphenol oxidase: purification and characterization. | polyphenol oxidase from iceberg lettuce (lactuca sativa l.) chloroplasts was released from the thylakoid-membrane by sonication, and it was extensively purified to homogeneity as judged by sds-page. purification was achieved by ammonium sulfate fractionation, gel-filtration chromatography, and ion-exchange chromatography. two molecular forms were separated by gel-filtration chromatography with apparent molecular masses of 188 and 49 kda. both forms were characterized by sedimentation analysis wi ... | 2001 | 11600037 |
| four polyoxygenated cyclohexenes from the chinese tree, uvaria purpurea. | two novel polyoxygenated cyclohexenes, 6-methoxyzeylenol (3) and 2-acetoxyzeylenone (4), together with two known compounds, zeylenol (1) and zeylenone (2), were isolated from the heartwood of the chinese tree, uvaria purpurea. zeylenol (1) and zeylenone (2) both showed inhibitory activity toward the root growth of lactuca sativa. their structures were established by spectroscopic and chemical methods. | 2001 | 11471741 |
| allelopathy, dimboa production and genetic variability in accessions of triticum speltoides. | a screening was conducted to study the allelopathic potential of australian-held accessions of triticum speltoides. of 26 accessions, four were found to inhibit root growth in the indicator species, lettuce (lactuca sativa). the methanol leaf extracts of these accessions significantly reduced the root length of wild oat (avena spp.). in all but one case, alellopathic accessions contained higher amounts of dimboa than did nonallelopathic accessions. since some variation in allelopathic response w ... | 2001 | 11446298 |
| responses of plant growth rate to nitrogen supply: a comparison of relative addition and n interruption treatments. | this paper investigates the effects of uptake of nitrate and the availability of internal n reserves on growth rate in times of restricted supply, and examines the extent to which the response is mediated by the different pools of n (nitrate n, organic n and total n) in the plant. hydroponic experiments were carried out with young lettuce plants (lactuca sativa l.) to compare responses to either an interruption in external n supply or the imposition of different relative n addition rate (rar) tr ... | 2001 | 11283176 |
| preparation and biological activity of four epiprogoitrin myrosinase-derived products. | (5r)-5-vinyl-1,3-oxazolidine-2-thione, (2s)-1-cyano-2-hydroxy-3-butene, and two diastereoisomeric erythro-(2s)- and threo-(2s)-1-cyano-2-hydroxy-3,4-epithiobutanes were prepared in pure form starting from (2s)-2-hydroxybut-3-enyl glucosinolate (epiprogoitrin). this glucosinolate was isolated in almost pure form using ripe seeds of crambe abyssinica and then hydrolyzed under different conditions. the hydrolysis was carried out using either myrosinase immobilized on nylon, to produce (5r)-5-vinyl- ... | 2001 | 11170613 |
| effect of wounding on phenolic enzymes in six minimally processed lettuce cultivars upon storage. | the effect of wounding on polyphenol oxidase (ppo), peroxidase (pod), and phenylalanine ammonia-lyase (pal) was studied in six minimally processed lettuce (lactuca sativa l.) cultivars upon storage for 7 days at 5 degrees c (iceberg mikonos (im), i. green queen (igq), i. asdrúbal (ia), little gem sandra (lgs), romaine cazorla (rc), and r. modelo (rm)). wounding of lettuce tissue midribs (because of minimal processing) caused an exponential increase in ppo activity due to the activation process f ... | 2001 | 11170594 |
| [disinfection treatment for lettuces (lactuca sativa) and strawberries (fragatia chiloensis)]. | the disinfection of vegetables and fruits is a treatment applied in order to reduce their natural contamination or processes to the product along the different steps of the food chain until its consumption. in the present work the effect of two disinfectants products was studied: grapefruit seed extract (400 ppm) for 10 min and peracetic acid (2000 ppm) for 1 min (action times assayed according to the manufacturer recommendations) and other additional times. the germicidal action was carried out ... | 2001 | 12012564 |
| a comparison of sole carbon source utilization patterns and phospholipid fatty acid profiles to detect changes in the root microflora of hydroponically grown crops. | sole carbon source utilization (scsu) patterns and phospholipid fatty acid (plfa) profiles were compared with respect to their potential to characterize root-inhabiting microbial communities of hydroponically grown crops. sweet pepper (capsicum annum cv. evident), lettuce (lactuca sativa cv. grand rapids), and four different cultivars of tomato (lycopersicon esculentum cvs. gitana, armada, aromata, and elin) were grown in 1-l black plastic beakers placed in a cultivation chamber with artificial ... | 2001 | 11358169 |
| potential allelochemicals from sambucus nigra. | twenty-four aromatic metabolites belonging to cyanogenins, lignans, flavonoids, and phenolic glycosides were obtained from sambucus nigra. structures were determined on the basis of their spectroscopic features. two compounds have been isolated and identified as (2s)-2-o-beta-d-glucopyranosyl-2-hydroxyphenylacetic acid and benzyl 2-o-beta-d-glucopyranosyl-2,6-dihydroxybenzoate. all the compounds have been assayed on dicotyledons lactuca sativa (lettuce) and raphanus sativus (radish) and monocoty ... | 2001 | 11730871 |
| recombination and spontaneous mutation at the major cluster of resistance genes in lettuce (lactuca sativa). | two sets of overlapping experiments were conducted to examine recombination and spontaneous mutation events within clusters of resistance genes in lettuce. multiple generations were screened for recombinants using pcr-based markers flanking dm3. the dm3 region is not highly recombinagenic, exhibiting a recombination frequency 18-fold lower than the genome average. recombinants were identified only rarely within the cluster of dm3 homologs and no crossovers within genes were detected. three popul ... | 2001 | 11157000 |
| one ring or two? determination of ring number in carotenoids by lycopene epsilon-cyclases. | carotenoids in the photosynthetic membranes of plants typically contain two beta-rings (e.g., beta-carotene and zeaxanthin) or one epsilon- and one beta-ring (e.g., lutein). carotenoids with two epsilon-rings are uncommon. we reported earlier that the arabidopsis thaliana lycopene epsilon-cyclase (lcye) adds one epsilon-ring to the symmetrical linear substrate lycopene, whereas the structurally related lycopene beta-cyclase (lcyb) adds two beta-rings. here we describe a cdna encoding lcye in rom ... | 2001 | 11226339 |
| assessment of toxicity reduction after metal removal in bioleached sewage sludge. | sewage sludge can be applied to land to supply and recycle organic matter and nutrients. trace elements in sludge, however, may accumulate in the soil with repeated sludge applications. reducing metal content may therefore reduce the adverse effects of sludge application. the objective of this study was to evaluate the efficiency of bioleaching technology in reducing metal content and toxicity as measured by a battery of terrestrial and liquid-phase bioassays. sludge-soil mixtures simulating the ... | 2001 | 11317888 |
| interlaboratory study for the validation of an ecotoxicological procedure to monitor the quality of septic sludge received at a wastewater treatment plant. | septic tank sludge is regularly hauled to the montreal urban community (muc) wastewater treatment plant. it is then discharged and mixed with the wastewater inflow before entering the primary chemical treatment process. an ecotoxicological procedure integrating chemical and toxicological analyses has been recently developed and applied to screen for the illicit discharge of toxic substances in septic sludge. the toxicity tests used were the microtox, the bacterial-respiration, and the lettuce (l ... | 2001 | 11339716 |
| the use of acute and chronic bioassays to determine the ecological risk and bioremediation efficiency of oil-polluted soils. | to compare the effectiveness of acute and chronic bioassays for the ecological risk assessment of polluted soils, soil samples from a site with an historical mineral oil contamination (< 50-3,300 mg oil/kg dry soil) at the petroleum harbour in amsterdam, the netherlands, were screened for ecological effects using acute and chronic bioassays. a two-step 0.001 m ca(no3)2 extraction at a final solution-to-soil ratio of 1:1 was used to prepare extracts for the acute bioassays. acute bioassays (< or ... | 2001 | 11434283 |
| production of dwarf lettuce by overexpressing a pumpkin gibberellin 20-oxidase gene. | we investigated the effect of overexpressing a pumpkin gibberellin (ga) 20-oxidase gene encoding an enzyme that forms predominantly biologically inactive products on ga biosynthesis and plant morphology in transgenic lettuce (lactuca sativa cv vanguard) plants. lettuce was transformed with the pumpkin ga 20-oxidase gene downstream of a strong constitutive promoter cassette (el2-35s-omega). the transgenic plants in which the pumpkin gene was detected by polymerase chain reaction were dwarfed in t ... | 2001 | 11457947 |
| chemical immobilization of lead, zinc, and cadmium in smelter-contaminated soils using biosolids and rock phosphate. | chemical immobilization, an in situ remediation method where inexpensive chemicals are used to reduce contaminant solubility in contaminated soil, has gained attention. we investigated the effectiveness of lime-stabilized biosolid (lsb), n-viro soil (nv), rock phosphate (rp), and anaerobic biosolid (ab) to reduce extractability and plant and gastrointestinal (gi) bioavailability in three cd-, pb-, and zn-contaminated soils from smelter sites. treated (100 g kg(-1) soil) and control soils were in ... | 2001 | 11476499 |
| effects of p(sag12)-ipt gene expression on development and senescence in transgenic lettuce. | an ipt gene under control of the senescence-specific sag12 promoter from arabidopsis (p(sag12)-ipt) significantly delayed developmental and postharvest leaf senescence in mature heads of transgenic lettuce (lactuca sativa l. cv evola) homozygous for the transgene. apart from retardation of leaf senescence, mature, 60-d-old plants exhibited normal morphology with no significant differences in head diameter or fresh weight of leaves and roots. induction of senescence by nitrogen starvation rapidly ... | 2001 | 11598225 |
| overexpression of knat1 in lettuce shifts leaf determinate growth to a shoot-like indeterminate growth associated with an accumulation of isopentenyl-type cytokinins. | leaves are specialized organs characterized by defined developmental destiny and determinate growth. the overexpression of knotted1-like homeobox genes in different species has been shown to alter leaf shape and development, but a definite role for this class of genes remains to be established. transgenics that overexpress knotted1-like genes present some traits that are characteristic of altered cytokinin physiology. here we show that lettuce (lactuca sativa) leaves that overexpress knat1, an a ... | 2001 | 11500537 |
| [the effect of postradiation storage on the mutation process and germination of lettuce seeds (lactuca sativa) irradiated with co 60 gamma-rays]. | 2001 | 5052700 | |
| inheritance of resistance to the root-knot nematode meloidogyne javanica in lettuce. | resistance to the root-knot nematodes meloidogyne spp. would be a valuable attribute of lettuce lactuca sativa l. cultivars grown in tropical regions. the looseleaf lettuce 'grand rapids' is resistant to both m. incognita and m. javanica. resistance to m. incognita has a high heritability, under the control of a single gene locus, in which the 'grand rapids' allele, responsible for resistance (me), has predominantly additive gene action, and has incomplete penetrance and variable expressivity. w ... | 2002 | 14963814 |
| suspending lettuce type influences recoverability and radiation sensitivity of escherichia coli o157:h7. | an outbreak strain of escherichia coli o157:h7 was inoculated onto closely related but structurally distinct types of lettuce (lactuca sativa): boston (butterhead lettuce), iceberg (crisphead lettuce), and green leaf and red leaf (colored variants of looseleaf lettuce). the e. coli o157:h7 was inoculated either onto the surface of cut leaf pieces or into a homogenized leaf suspension. samples were gamma irradiated, and the radiation sensitivity of the inoculated bacteria was expressed as a d-val ... | 2002 | 12233847 |
| soil-to-root transfer and translocation of polycyclic aromatic hydrocarbons by vegetables grown on industrial contaminated soils. | polycyclic aromatic hydrocarbons (pahs) are possible contaminants in some former industrial sites, representing a potential risk to human health if these sites are converted to residential areas. this work was conducted to determine whether pahs present in contaminated soils are transferred to edible parts of selected vegetables. soils were sampled from a former gasworks and a private garden, exhibiting a range of pah concentrations (4 to 53 to 172 to 1263 and 2526 mg pahs kg-1 of dry soil), and ... | 2002 | 12371182 |
| [detection of enterococcus with high-level aminoglycoside and glycopeptide resistance in lactuca sativa (lettuce)]. | the aim of this study was to assess the presence of enterococci highly resistant to aminoglycosides and glycopeptides in foods eaten uncooked, in order to evaluate their role as reservoirs of antimicrobial resistance. | 2002 | 12372233 |
| phytol, ssadh inhibitory diterpenoid of lactuca sativa. | the succinic semialdehyde dehydrogenase (ssadh) inhibitory component was isolated from the etoac fraction of lactuca sativa through repeated column chromatography; then, it was identified as phytol, a diterpenoid, based on the interpretation of several spectral data. incubation of ssadh with the phytol results in a time-dependent loss of enzymatic activity, suggesting that enzyme modification is irreversible. the inactivation followed pseudo-first-order kinetics with the second-rate order consta ... | 2002 | 12433198 |
| effect of acute ingestion of fresh and stored lettuce (lactuca sativa) on plasma total antioxidant capacity and antioxidant levels in human subjects. | the present study investigated whether storage under modified-atmosphere packaging (map) affected the antioxidant properties of fresh lettuce (lactuca sativa). eleven healthy volunteers (six men, five women) consumed 250 g fresh lettuce, and blood was sampled before (0 h) and 2, 3 and 6 h after consumption. the protocol was repeated 3 d later with the same lettuce stored at 5 degrees c under map conditions (o2-n2 (5:95, v/v)). results showed that after ingestion of fresh lettuce, plasma total ra ... | 2002 | 12493083 |
| lactuca saligna, a non-host for lettuce downy mildew ( bremia lactucae), harbors a new race-specific dm gene and three qtls for resistance. | lactuca sativa (lettuce) is susceptible to bremia lactucae (downy mildew). in cultivated and wild lactuca species, dm genes have been identified that confer race-specific resistance. however, these genes were soon rendered ineffective by adaptation of the pathogen. lactuca saligna (wild lettuce) is resistant to all downy mildew races and can be considered as a non-host. therefore, l. saligna might be an alternative source for a more-durable resistance to downy mildew in lettuce. in order to anal ... | 2002 | 12582542 |
| an ecotoxic risk assessment of residue materials produced by the plasma pyrolysis/vitrification (pp/v) process. | plasma is the fourth state of matter, following the three states of solid, liquid and gas. experience has amply demonstrated that solids exposed to the oxygen-deficient plasma flame are converted to liquid, and liquid exposed to the same flame is converted to gas. a low amount of vitrified solid residue material usually remains at the end of this process. plasma pyrolysis/vitrification (pp/v) has been demonstrated as a safe, efficient, cost-effective technology for the treatment of wastes, inclu ... | 2002 | 11952180 |
| cloning, expression, and biological activity of recombinant alpha-cinnamomin: toxicity to cranberry and other plant species. | elicitins produced by the pathogenic fungi phytophthora are known to exhibit the elicitin cinnamomin is of nonspecific toxicity to different solanaceous plant species. particular interest for its potential role in the hypersensitive-like cell death and in the biological response of cranberry plants to the fungal pathogen phytophthora cinnamomi. in order to understand the biochemical steps of the phytophthora root rot disease in cranberry, we investigated the alpha-cinnamomin-induced plant respon ... | 2002 | 12009117 |
| cloning and expression of sesquiterpene synthase genes from lettuce (lactuca sativa l.). | sesquiterpenoid lactones (sls) from lettuce (lactuca sativa l.) include constitutive components of latex such as lactucin and the induced phytoalexin, lettucenin a. a redundant primer strategy was used to recover two full length cdna clones (ltc1 and ltc2) encoding sesquiterpene synthases from a cdna library derived from seedlings with the red spot disorder, which accumulate phytoalexins. recombinant enzymes produced from ltc1 and ltc2 in escherichia coli catalysed the cyclisation of farnesyl di ... | 2002 | 12031443 |
| overview of results from the watertox intercalibration and environmental testing phase ii program: part 1, statistical analysis of blind sample testing. | there is an urgent need to evaluate the presence of toxicants in waters used for human consumption and to develop strategies to reduce and prevent their contamination. the international development research centre undertook an intercalibration project to develop and validate a battery of bioassays for toxicity testing of water samples. the project was carried out in two phases by research institutions from eight countries that formed the watertox network. results for the first phase were reporte ... | 2002 | 12112631 |
| ecotoxicological assessment of leachates from mswi bottom ashes. | in this paper, chemical and ecotoxicological data of leachates from bottom ashes collected in different municipal solid waste incinerators (mswi) are shown. the bottom ashes were collected in belgium (three incinerators--samples b1 to b3), france, germany, italy and united kingdom (one incinerator in each country--samples f1, d1, i1 and uk1, respectively). both chemical and ecotoxicological characterizations of leachates were done on the framework of the european directive 91/689/eec and the eur ... | 2002 | 12214969 |
| microbiological determinations of some vegetables from the xochimilco zone in mexico city, mexico. | vegetables intake is widely recommended because of its high content of vitamins, minerals and fiber. however, the irrigation of these vegetables, using wastewaters that have received inadequate treatment often carries unseen microbial pollution that becomes a high risk potential for humans. in the present research, two of the most consumed fresh vegetables cultivated in mexico city were analyzed, lettuce (lactuca sativa) and mexican coriander (eryngium foetidum). these vegetables are commonly co ... | 2002 | 17061512 |
| quality of water types in ukraine evaluated by watertox bioassays. | the quality of river, ground-, and tap water was analyzed using the basic set of watertox bioassays [daphnia (daphnia magna), hydra (hydra attenuata), and lettuce (lactuca sativa)] as well as two additional bioassays, onion (allium cepa) and microalga (selenastrum gracile). samples of these waters were also concentrated fivefold using a solid-phase procedure. the results of the daphnia and hydra bioassays showed that the winter and spring concentrated and nonconcentrated samples from the dnieper ... | 2002 | 12112633 |
| a novel nucleolar biomarker in plant and animal cells for assessment of substance cytotoxicity. | the cytotoxicity of three substances (mercury(ii), metolachlor, and 4-nitroquinoline-n-oxide) was assessed with a set of nucleolar parameters: the average number of nucleoli, the average volume of a single nucleolus, and the proportion of cells with heteromorphic-paired nucleoli (pnhet). their toxic impact was studied on cells of animal and plant test organisms: onion (allium cepa), lettuce (lactuca sativa), and hydra (hydra attenuata). in general, at concentrations near ic/lc(50) the three chem ... | 2002 | 12112626 |
| toxicity of methyl tert-butyl ether to plants (avena sativa, zea mays, triticum aestivum, and lactuca sativa). | influence of methyl tert-butyl ether (mtbe) on the germination of seeds and growth of seedling plants were studied in laboratory experiments. test plants were wild oats (avena sativa), sweet corn (zea mays), wheat (triticum aestivum), and lettuce (lactuca sativa). seed germination, shoot growth, and root growth of plants exposed to different concentrations of mtbe in a moist soil were examined. seed germination and seedling growth in mtbe-contaminated soil were markedly reduced in all test plant ... | 2002 | 12152769 |
| overview of results from the watertox intercalibration and environmental testing phase ii program: part 2, ecotoxicological evaluation of drinking water supplies. | because of rapid population growth, industrial development, and intensified agricultural production increasing amounts of chemicals are being released into the environment, polluting receiving water bodies around the world. given the potential health risk associated with the presence of toxicants in water sources used for drinking yet the scarcity of available data, there is a need to evaluate these waters and develop strategies to reduce and prevent their contamination. the present study examin ... | 2002 | 12112632 |
| polyoxygenated cyclohexenes from the chinese tree, uvaria purpurea. | four new polyoxygenated cyclohexenes, 2-o-acetyl-6-o-methylzeylenol (2), 2-o-benzoyl-3-o-debenzoylzeylenone (5), 3-o-debenzoylzeylenone (6) and 3-o-debenzoylgrandiflorone (8), were isolated from the leaves of uvaria purpurea. 2-o-acetyl-6-o-benzoylzeylenol (3) was also isolated for the first time as a natural product. compounds 5-7 each showed inhibitory activity against the root growth of lactuca sativa. their structures were established by spectroscopic and chemical methods. | 2002 | 12005046 |
| involvement of putative chemical wound signals in the induction of phenolic metabolism in wounded lettuce. | cutting leaves of romaine lettuce (lactuca sativa l. cv. longifolia) produces a wound signal that induces the synthesis of phenylalanine ammonia lyase (pal, ec 4.3.1.5) and the accumulation of phenolic compounds in cells up to 2 cm from the site of injury, and tissue browning near the site of injury. the response of leaves within a head of romaine lettuce to putative chemical wound signals [abscisic acid (aba), jasmonate (ja) and methyl jasmonate (meja)] differed significantly with leaf age. exp ... | 2002 | 11982937 |
| characterization of "lettucine", a serine-like protease from lactuca sativa leaves, as a novel enzyme for milk clotting. | in this work we focused on the characterization of a novel plant rennet purified from lettuce leaves (lactuca sativa l. cv romana). the lettuce protease, lettucine, showed trypsin-like, sv8-like, and caseinolytic activities. although the enzyme did not recognize peptides having hydrophobic amino acid residues in the p(1) position of the target bond, it did show milk-clotting activity, suggesting that different bonds rather than the phe(105)-met(106) of the kappa-casein might be cleaved, still in ... | 2002 | 11929310 |
| isolation and identification of an allelopathic substance from peel of citrus junos. | the inhibitory effect of citrus junos peel on plant growth using lettuce (lactuca sativa l.) as a bioassay material was investigated, since the powder of the peel had been found to inhibit growth of weeds. basic, neutral and acidic fractions were separated from the aqueous fraction obtained from the methanol extract of c. junos peel. all fractions inhibited the growth of lettuce seedlings, but by far the greatest inhibition was observed with the neutral fraction. thus, the latter was further pur ... | 2002 | 12453578 |
| resistance to adult banded cucumber beetle (coleoptera: chrysomelidae) in romaine lettuce. | four cultivars of lettuce, lactuca sativa l., were evaluated for their resistance to the adult banded cucumber beetle, diabrotica balteata leconte, under laboratory conditions. when paired with each of the other three cultivars, leaf consumption in all possible combinations of short-term (48 h) two-choice tests among the cultivars was significantly reduced only for 'valmaine'. however, in a 48-h no-choice situation, beetles fed valmaine or 'short guzmaine' had similarly low leaf consumption, fol ... | 2002 | 12216830 |
| effect of wash water temperature and chlorination on phenolic metabolism and browning of stored iceberg lettuce photosynthetic and vascular tissues. | cut tissues from distinct anatomical locations in iceberg lettuce (lactuca sativa l.) were subjected to washing in cold (4 degrees c) and warm (47 degrees c) water with or without chlorine to assess their propensity to discoloration during storage. total protein (bradford method) and phenolic (tph; folin-ciocalteu method) contents and polyphenol oxidase (ppo; spectrophotometric method using catechol as a substrate), peroxidase (pod; guaiacol substrate), and phenylalanine ammonia-lyase (pal; phen ... | 2002 | 12137468 |
| transfer of the fungicide vinclozolin from treated to untreated plants via volatilization. | head lettuce plantlets (lactuca sativa l. var. capitata) were potted, treated with vinclozolin at the six-leaf stage according to application standards and allowed to dry for 24 h. the potted plantlets were then placed in either growth chambers with controlled temperature (20 and 25 degrees c, respectively) or in a greenhouse (approximately 12 degrees c), together with untreated spinach (spinacia oleracea l.) and standardized grass cultures (lolium multiflorum lam. ssp.) while the treated lettuc ... | 2002 | 12137060 |
| isolation and identification of a potent allelopathic substance in rice root exudates. | a search for growth inhibitors in rice root exudates was undertaken in order to clarify the allelopathic system in rice (oryza sativa l.). rice seedlings inhibited the growth of cress (lepidium sativum l.) and lettuce (lactuca sativa l.) seedlings when the cress and lettuce were grown with rice seedlings. the putative compound causing the inhibitory effect of rice seedlings was isolated from their culture solution, and the chemical structure of the inhibitor was determined by spectral data as mo ... | 2002 | 12081533 |
| [genetic ecology of rice allelopathy on receiver plant]. | in this study, 5 parental rice lines with different allelopathic potential were employed in partial diallel cross (4 x 5) to get 10 groups of f1 seeds. after testing the inhibitory effects of 5 parents and 10 f1s under different environment at different leaf stage on the shoot length of receiver plant lettuce(lactuca sativa l.), dynamic genetics of rice allelopathy and its genotype x environment effects were analyzed by using additive-dominant developmental genetic models. the results showed tha ... | 2002 | 12682960 |
| germination and growth of lettuce (lactuca sativa) at low atmospheric pressure. | the response of lettuce (lactuca sativa l. cv. waldmann's green) to low atmospheric pressure was examined during the initial 5 days of germination and emergence, and also during subsequent growth to vegetative maturity at 30 days. growth took place inside a 66-l-volume low pressure chamber maintained at 70 kpa, and plant response was compared to that of plants in a second, matching chamber that was at ambient pressure (approximately 101 kpa) as a control. in other experiments, to determine short ... | 2002 | 12583399 |
| new type of dual-channel pam chlorophyll fluorometer for highly sensitive water toxicity biotests. | a new type of dual-channel pam chlorophyll fluorometer has been developed, which is specialised in the detection of extremely small differences in photosynthetic activity in algae or thylakoids suspensions. in conjunction with standardised algae cultures or isolated thylakoids, the new device provides an ultrasensitive biotest system for detection of toxic substances in water samples. in this report, major features of the new device are outlined and examples of its performance are presented usin ... | 2002 | 16245142 |
| 4,4,4-trifluoro-3-(indole-3-)butyric acid promotes root elongation in lactuca sativa independent of ethylene synthesis and ph. | we studied the mode of action of 4,4,4-trifluoro-3- (indole-3-) butyric acid (tfiba), a recently described root growth stimulator, on primary root growth of lactuca sativa l. seedlings. tfiba (100 micromoles) promoted elongation of primary roots by 40% in 72 h but inhibited hypocotyl growth by 35%. tfiba induced root growth was independent of ph. tfiba did not affect ethylene production, but reduced the inhibitory effect of ethylene on root elongation. tfiba promoted root growth even in the pres ... | 2002 | 12542053 |
| phytotoxicity of 2,4,6-trinitrotoluene (tnt) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (hmx) in spiked artificial and natural forest soils. | toxicity of 2,4,6-trinitrotoluene (tnt) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (hmx) using two terrestrial plant species, lettuce (lactuca sativa) and barley (hordeum vugare), was assessed in artificial soil (silica) and forest soil. lettuce emergence was significantly decreased after 5 days of exposure to tnt nominal spiked concentrations >/= 1,040 mg/kg dry soil in silica. barley emergence was significantly reduced after 14 days of exposure at initial (t = 0) tnt concentrations > ... | 2003 | 12520392 |
| isolation and characterization of the acc synthase genes from lettuce (lactuca sativa l.), and the involvement in low ph-induced root hair initiation. | root hair formation is induced when lettuce seedlings are transferred from ph 6.0 to ph 4.0. ethylene, auxin and light are essential to this process. to investigate the role of ethylene in root hair initiation, we isolated two 1-aminocyclopropane-1-carboxylic acid (acc) synthase genes (ls-acs1 and ls-acs2). seven motifs of known acs proteins were highly conserved in ls-acs1 and ls-acs2. the ls-acs1 and ls-acs2 mrna levels were constant at ph 6.0, which were lower than that in seedlings at ph 4.0 ... | 2003 | 12552148 |
| randomization of cortical microtubules in root epidermal cells induces root hair initiation in lettuce (lactuca sativa l.) seedlings. | root hair formation is induced when lettuce seedlings are transferred from liquid medium at ph 6.0 to fresh medium at ph 4.0. if seedlings are transferred to ph 6.0, no root hairs are formed. we investigated the role of microtubules in this low ph-induced root hair initiation in lettuce. at the hair-forming zone in root epidermal cells, microtubules were perpendicular to the longitudinal axis of the cell just after pre-culture. this arrangement became disordered as early as 5 min after transfer ... | 2003 | 12668782 |
| characterization and genetic analysis of a lettuce (lactuca sativa l.) mutant, weary, that exhibits reduced gravitropic response in hypocotyls and inflorescence stems. | a lettuce (lactuca sativa l.) mutant that exhibits a procumbent growth habit was identified and characterized. in two wild type (wt) genetic backgrounds, segregation patterns revealed that the mutant phenotype was controlled by a recessive allele at a single locus, which was designated weary. hypocotyls and inflorescence stems of plants homozygous for the weary allele exhibited reduced gravitropic responses compared with wt plants, but roots exhibited normal gravitropism. microscopic analysis re ... | 2003 | 12654877 |
| isolation and identification of an allelopathic substance in pisum sativum. | the residue of peas (pisum sativum l.) has allelopathic activity and the putative compound causing this inhibitory effect was isolated from a methanol extract of pea shoots. chemical structure of this compound was determined by high-resolution ms, ir and 1h nmr spectral data as pisatin. pisatin inhibited growth of cress (lepidium sativum l.) and lettuce (lactuca sativa l.) seedlings at concentrations greater than 10 and 30 microm, respectively. the doses required for 50% growth inhibition of roo ... | 2003 | 12591269 |
| determining toxicity of lead and zinc runoff in soils: salinity effects on metal partitioning and on phytotoxicity. | when assessing cationic metal toxicity in soils, metals are often added to soil as the chloride, nitrate, or sulfate salts. in many studies, the effects of these anions are ignored or discounted; rarely are appropriate controls included. this study used five soils varying in ph, clay content, and organic matter to determine whether salinity from counter-ions contributed to or confounded metal phytotoxicity. varying rates of pb and zn were applied to soils with or without a leaching treatment to ... | 2003 | 14713044 |
| isolation and structural characterization of a water-soluble germination inhibitor from scotch thistle (onopordum acanthium) cypselas. | cypsela dormancy in scotch thistle (onopordum acanthium) may be affected by the presence of chemical inhibitors. to investigate this phenomenon, a leachate from o. acanthium cypselas was tested for its ability to inhibit germination of the cypselas from which it was derived (i.e., autoinhibition). leachates varied in their degree of autoinhibition, depending on the cypsela population from which they were prepared. overall, removal of leachate from a group of o. acanthium cypselas increased their ... | 2003 | 14682524 |
| effects of monoterpenoids, acting alone or in pairs, on seed germination and subsequent seedling growth. | we compared the potential allelopathic activity of 47 monoterpenoids of different chemical groups, by estimating their effect on seed germination and subsequent growth of lactuca sativa seedlings. apart from individual compounds, eleven pairs at different proportions were also tested. as a group, the hydrocarbons, except for (+)-3-carene, were the least inhibitory. of the oxygenated compounds, the least inhibitory were the acetates; whenever the free hydroxyl group of an alcohol turned into a ca ... | 2003 | 14682512 |
| volatile allelopathy in velvet bean (mucuna pruriens [correction of pruiens] l.) and gravity. | allelopathy caused by volatile compounds was studied with velvet bean (mucuna pruriens [correction of prueiens] l.). preparatory experiment was conducted to identify the relationship between action of volatiles and gravity. the experimental protocol was defined and tested to study on volatile allelopathy of velvet bean. root growth of lettuce (lactuca sativa l.) seedlings was inhibited by volatile gas from velvet bean seedlings planted in agripot. in this study, it was shown that ten-day velvet ... | 2003 | 14676381 |
| snp-based codominant markers for a recessive gene conferring resistance to corky root rot (rhizomonas suberifaciens) in lettuce (lactuca sativa). | the analysis of f2 progeny and derived f3 families of lactuca sativa segregating for resistance to corky root rot caused by rhizomonas suberifaciens permitted the identification of restriction fragment length polymorphism (rflp) and single nucleotide polymorphism (snp) markers linked to the recessive resistance gene cor. pcr-based markers were identified by bulked segregant analysis (bsa). allele-specific primers were generally designed with the 3 terminal base coinciding with an snp, matching o ... | 2003 | 14663524 |
| effect of hypobaric conditions on ethylene evolution and growth of lettuce and wheat. | elevated levels of ethylene occur in enclosed crop production systems and in spaceflight environments, leading to adverse plant growth and sterility. there are engineering advantages in growing plants at hypobaric (reduced atmospheric pressure) conditions in biomass production for extraterrestrial base or spaceflight environments. objectives of this research were to characterize the influence of hypobaria on growth and ethylene evolution of lettuce (lactuca sativa) and wheat (triticum aestivum). ... | 2003 | 14658387 |
| ethylene promotes the induction by auxin of the cortical microtubule randomization required for low-ph-induced root hair initiation in lettuce (lactuca sativa l.) seedlings. | transverse cortical microtubule (cmt) arrays in lettuce root epidermal cells randomize soon after a shift from ph 6.0 to ph 4.0, and this randomization is essential for root hair initiation. we investigated the hormonal regulation of cmt randomization. at ph 4.0, 1 micro m of the auxin competitive inhibitor 2-(p-chlorophenoxy)-2-methylpropionic acid (pcib), 0.1 micro m of the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (avg) or 0.1 micro m of the ethylene action inhibitor ag(+) suppr ... | 2003 | 14519775 |
| deactivation of gibberellin by 2-oxidation during germination of photoblastic lettuce seeds. | gibberellin (ga) plays an important role in the induction of germination of photoblastic lettuce (lactuca sativa l. cv. grand rapids) seeds. we have previously shown that gene expression of a ga 3-oxidase (ls3h1) increased after a red light treatment, resulting in an increase in the endogenous content of ga1, bioactive ga. since the metabolism of gas is also important for determining the endogenous levels of bioactive gas, cdnas encoding ga 2-oxidases (lsga2ox1 and lsga2ox2, for l. sativa ga 2-o ... | 2003 | 12913300 |
| reduced allelopathic inhibition of lettuce (lactuca sativa) growth caused by velvet bean (mucuna pruriens) under 3d-clinorotation. | allelopathy between mucuna pruriens (velvet bean) and lactuca sativa (lettuce) was studied under 3d-clinorotation. growth of both roots and shoots of lettuce seedlings was suppressed by the presence of velvet bean. the degree of suppression was less on the clinostat compared to the normal static earth gravity. l-dopa (l-3, 4-dihydroxyphenylalanine) is known to be a major substance in allelopathy of velvet bean. amount of l-dopa diffused out from a sintered filter paper into agar medium was compa ... | 2003 | 12897456 |
| the nitrogen and nitrate economy of butterhead lettuce (lactuca sativa var capitata l). | quantifying and simulating the relationships between crop growth, total-nitrogen (total-n) and nitrate-n (no3--n) concentration can improve crop nutritional husbandry. in this study, the relationship between shoot relative growth rate (rgr) and shoot total-n, organic-n and no3--n concentration of hydroponically-grown lettuce (lactuca sativa var. capitata l. cv. kennedy) was described and simulated. plants were grown hydroponically for up to 74 d. nitrogen was supplied throughout (control; t1), o ... | 2003 | 12885858 |
| a new algorithm for computational image analysis of deformable motion at high spatial and temporal resolution applied to root growth. roughly uniform elongation in the meristem and also, after an abrupt acceleration, in the elongation zone. | a requirement for understanding morphogenesis is being able to quantify expansion at the cellular scale. here, we present new software (rootflowrt) for measuring the expansion profile of a growing root at high spatial and temporal resolution. the software implements an image processing algorithm using a novel combination of optical flow methods for deformable motion. the algorithm operates on a stack of nine images with a given time interval between each (usually 10 s) and quantifies velocity co ... | 2003 | 12857796 |
| role of manganese in low-ph-induced root hair formation in lactuca sativa cv. grand rapids seedlings. | root hair formation is induced by low ph in lettuce ( lactuca sativa l. cv. grand rapids) seedlings cultured in mineral medium. the role of mineral concentrations in this phenomenon was investigated, especially for manganese. when lettuce seedlings were cultured in media that were deficient in calcium (ca), manganese (mn), boron (b) or molybdenum (mo), morphological changes were induced in roots. deficiency of other nutrients had little effect on root hair formation. ca or b deficiency inhibited ... | 2003 | 12750946 |
| herbicidal, plant growth inhibitory, and cytotoxic activities of bismuthines containing aromatic heterocycles. | this work presents the herbicidal and plant growth regulatory activities of tertiary bismuthines containing heterocyclic aromatic rings of the general formula (2-c(4)h(3)x)(3)bi, where x = s (3), o (1), or nme (2). toxicity against artemia salina and herbicidal activity on lactuca sativa, trifolium pratense, and lolium multiflorum were tested. in addition to the effects on mitochondrial respiration obtained from roots of phaseolus vulgaris, these compounds also demonstrated partial radical scave ... | 2003 | 12720372 |
| phytotoxicity to and uptake of enrofloxacin in crop plants. | phytotoxicity of enrofloxacin on crop plants cucumis sativus, lactuca sativa, phaseolus vulgaris and raphanus sativus was determined in a laboratory model: the effect of 50, 100 and 5000 microgl(-1) were evaluated after 30 days exposure by measuring post-germinative growth of primary root, hypocotyl, cotyledons and leaves. concentrations between 50 and 5000 microgl(-1) induced both toxic effect and hormesis in plants, by significantly modifying both length of primary root, hypocotyl, cotyledons ... | 2003 | 12821004 |
| chemical stimulants of leaf-trenching by cabbage loopers: natural products, neurotransmitters, insecticides, and drugs. | larvae of the cabbage looper, trichoplusia ni (lepidoptera: noctuidae), often transect leaves with a narrow trench before eating the distal section. the trench reduces larval exposure to exudates, such as latex, during feeding. plant species that do not emit exudate, such as plantago lanceolata, are not trenched. however, if exudate is applied to a looper's mouth during feeding on p. lanceolata, the larva will often stop and cut a trench. dissolved chemicals can be similarly applied and tested f ... | 2003 | 14584674 |
| determination of vitamin c, b-carotene and riboflavin contents in five green vegetables organically and conventionally grown. | as consumer interest in organically grown vegetables is increasing in malaysia, there is a need to answer whether the vegetables are more nutritious than those conventionally grown. this study investigates commercially available vegetables grown organically and conventionally, purchased from retailers to analyse β-carotene, vitamin c and riboflavin contents. five types of green vegetables were selected, namely chinese mustard (sawi) (brassica juncea), chinese kale (kai-lan) (brassica alboglabra) ... | 2003 | 22692530 |