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PubMed2002

Regeneration of flowering plants from difficile lily protoplasts by means of a nurse culture.

The regeneration of difficile lily protoplasts isolated from suspension cells of the Oriental hybrid lily ( Lilium L.) cultivars Casablanca, Siberia and Acapulco was achieved by using the nurse-culture method. The divided protoplasts grew into colonies with nurse cells that have no regeneration ability, and developed to visible calli on a medium containing picloram. Many plantlets were formed on the calli after transfer of the proliferated calli to hormone-free medium. We were able to transplant the plantlets to soil in pots without acclimatization, and the plantlets grew in a greenhouse until flowering 2 years later.

Cells, Cultured↗

PubMed2003

Selection of hapten-specific single-domain antibodies from a non-immunized llama ribosome display library.

Picloram-specific variable fragments (V(HH)s) of heavy chain antibodies (HCAbs) were selected from a nai;ve-llama library using ribosome display technology. A cDNA library of V(HH)s was constructed from lymphocytes of a non-immunized llama and engineered to allow in vitro transcription and translation. With no stop codons present on the transcripts, trimeric complexes of ribosomes, mRNAs and nascent peptides were produced for affinity selection, i.e. panning. After three cycles of panning, seven different V(HH)s all belonging to the V(HH) subfamily 1 were isolated. Following another three cycles of selection, only two of the seven V(HH)s persisted. A comparison of these two sequences with known sequences in the literature suggests that point mutations may have been introduced into the DNA pool during PCR amplification steps of library construction, panning and/or cloning. Three separate point mutations causing three independent amino acid changes (nonsynonomous mutations) accumulated in the same sequence and enriched throughout the selection protocol, suggesting that these changes confer binding advantages. Surface plasmon resonance (SPR) analysis was used to determine binding kinetics of the two clones (3-1D2 and 3-1F6) representing the two different sets of isolated complementarity determining region (CDR)3s. Measured K(D)s were 3 and 254 muM, respectively. The results indicate that ribosome display technology can be used to efficiently isolate hapten-specific antibody (Ab) fragments from a nai;ve library and concurrently introduce diversity to the selected pool thereby facilitating molecular evolution. Ribosome display technology can compensate for the limited diversity of a V(HH) nai;ve library and provide an unlimited source of affinity-matured immunoactive reagents in vitro.

Amino Acid Sequence↗

PubMed2004

Proteome-level differences between auxinic-herbicide-susceptible and -resistant wild mustard (Sinapis arvensis L.).

To identify proteins that may be involved in mediating auxinic herbicide resistance (i.e., resistance to dicamba, picloram, 2,4-D), we compared the proteomes of an auxinic-herbicide-susceptible (S) and -resistant (R) wild mustard (Sinapis arvensis L.) biotype at different developmental stages. Using two-dimensional electrophoresis and mass spectrometry, we identified 11 seedling and leaf proteins that showed reproducible differences in expression between the S and the R wild mustard biotype following application of dicamba. Our proteome-level studies revealed the increased expression of the enzyme peptidylprolyl cis-trans isomerase (PPIase), which has recently been implicated in auxin signal transduction. Juglone, an inhibitor of PPIase, interfered with the normal ability of R seeds to germinate in the presence of dicamba, whereas S seeds did not germinate in the presence of dicamba or dicamba plus juglone. When R and S plants (3-4 leaf stage) were treated with dicamba, S showed typical auxinic herbicide effects (e.g., epinasty) whereas R did not. However, the concomitant application of dicamba and juglone to greenhouse-grown R plants produced morphological changes that were consistent with known auxinic-herbicide-induced symptoms. This is the first report suggesting the potential involvement of differential expression of PPIase in mediating auxinic herbicide resistance.

Dicamba↗

PubMed1996

Development of friable embryogenic callus and embryogenic suspension culture systems in cassava (Manihot esculenta Crantz)

Procedures for the production of a new and highly prolific embryogenic culture system have been developed in cassava. The importance of the basal salts and type of auxin in controlling the development of cassava embryogenic tissues has been demonstrated, with culture on Gresshoff and Doy basal medium in the presence of 4-amino-3,5,6,trichloro-picolinic acid (picloram) inducing the formation of friable embryogenic callus from which highly totipotent embryogenic suspension cultures could be established. Plants have been regenerated from these cultures. The availability of embryogenic suspension cultures is considered to have important implications for the application of genetic transformation and other biotechnologies in the agronomic improvement of cassava.

Culture Techniques↗

PubMed1989

Effects of gestational exposure to Tordon 202c on fetal growth and development in CD-1 mice.

The teratogenic effects of Tordon 202c, a picloram and 2,4-D combination formulation, are unknown. Pregnant CD-1 mice were exposed to Tordon 202c in the drinking water at concentrations of 0.10, 0.21, and 0.42% from d 6 to 15 of gestation. Fetal growth parameters, including body weight and crown-rump length, were reduced in a dose-dependent manner, as was placental weight. The incidence of dead fetuses/resorptions and malformed fetuses (especially cleft palate) was increased in the highest dosage group. A subtle indication of maternal toxicity was noted in the highest dosage group as evidenced by decreased water consumption and increased relative liver weight. The present study suggests that Tordon 202c is embryotoxic and teratogenic in CD-1 mice when administered during organogenesis.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1984

Occupational exposure of herbicide applicators to herbicides used along electric power transmission line right-of-way.

Occupational exposures to herbicides were measured among 12 applicators in 1979 and 24 applicators in 1980, who were applying the three herbicides, 2,4-D, dichloroprop and picloram to electric power transmission rights of ways. In 1979 only urine was analyzed but in 1980 both breathing-zone air samples and urine were analyzed for herbicide residues. Dermal absorption was found to be the major absorption route being up to 50 times greater than exposure by the inhalation route when using a hand gun sprayer. Even with the mist blower herbicide application method, dermal absorption was 4 and 11 times greater than exposure by the inhalation route. Worker education on hazards of skin contact and improved protective equipment significantly reduced the 1980 urine concentrations of herbicide residues. A model is presented to relate the urinary concentrations to equivalent daily exposure levels.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1992

Forest worker exposure to airborne herbicide residues in smoke from prescribed fires in the southern United States.

Occupational safety and health concerns have been raised in a number of southern states by workers conducting prescribed burns on forest lands treated with herbicides. Modeling assessments coupled with laboratory experiments have shown that the risk of airborne herbicide residues to workers is insignificant, even if the fire occurs immediately after herbicide application. However, no field studies had been conducted to confirm these findings. To bridge that gap, a field validation study was conducted in Georgia to measure breathing zone concentrations of smoke suspended particulate matter (SPM), herbicide residues, and carbon monoxide (CO) on 14 operational prescribed fires. Smoke was monitored on sites treated with labeled rates of forestry herbicides containing the active ingredients imazapyr, triclopyr, hexazinone, and picloram. The sites were burned within 30-169 days after herbicide application. Tract size ranged from 2.4 to 154 hectares. Personal monitors and area monitors employing glass fiber filters and polyurethane foam collection media were used. No herbicide residues were detected in the 140 smoke samples from the 14 fires conducted in this study. The sensitivity of the monitoring methods was in the 0.1 to 4.0 micrograms/m3 range, which is several hundred to several thousand times less than any established occupational exposure limit for herbicides. The SPM and CO monitored on these fires is the first time breathing zone concentrations of these smoke constituents have been measured in the South. As expected, concentrations were highly variable depending on fire conditions and the location of personnel. Worker respirable (2.3-microns particle cut point) SPM concentrations ranged between 0.2 and 3.7 mg/m3.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants, Occupational↗

PubMed2004

Hemoglobin promotes somatic embryogenesis in peanut cultures.

Critical parameters influencing somatic embryogenesis include growth regulators and oxygen supply. Consequently, the present investigation has focused on optimization of a somatic embryogenic system for peanut (Arachis hypogaea L.) through media supplementation with the auxin, picloram. The latter at 30 mg L(-1) was optimal for inducing regeneration of somatic embryos from cultured explants of zygotic embryos. In contrast, somatic embryogenesis did not occur in the absence of this growth regulator. An assessment has also been made of the beneficial effect on somatic embryogenesis and plant regeneration of the commercial hemoglobin (Hb) solution, Erythrogen. Hemoglobin at 1:50 and 1:100 (v:v) stimulated increases in mean fresh weight (up to a maximum of 57% over control), mean number of explants producing somatic embryos (15%) and mean number of somatic embryos per explant (29%).

Arachis↗

PubMed2006

Impact of data quality and model complexity on prediction of pesticide leaching.

Accurate input data for leaching models are expensive and difficult to obtain which may lead to the use of "general" non-site-specific input data. This study investigated the effect of using different quality data on model outputs. Three models of varying complexity, GLEAMS, LEACHM, and HYDRUS-2D, were used to simulate pesticide leaching at a field trial near Hamilton, New Zealand, on an allophanic silt loam using input data of varying quality. Each model was run for four different pesticides (hexazinone, procymidone, picloram and triclopyr); three different sets of pesticide sorption and degradation parameters (i.e., site optimized, laboratory derived, and sourced from the USDA Pesticide Properties Database); and three different sets of soil physical data of varying quality (i.e., site specific, regional database, and particle size distribution data). We found that the selection of site-optimized pesticide sorption (Koc) and degradation parameters (half-life), compared to the use of more general database derived values, had significantly more impact than the quality of the soil input data used, but interestingly also more impact than the choice of the models. Models run with pesticide sorption and degradation parameters derived from observed solute concentrations data provided simulation outputs with goodness-of-fit values closest to optimum, followed by laboratory-derived parameters, with the USDA parameters providing the least accurate simulations. In general, when using pesticide sorption and degradation parameters optimized from site solute concentrations, the more complex models (LEACHM and HYDRUS-2D) were more accurate. However, when using USDA database derived parameters, all models performed about equally.

Adsorption↗

PubMed1991

The effects of Tordon 202c exposure on urethan-induced lung adenoma formation in female CD-1 mice.

Female CD-1 mice were exposed to Tordon 202c, a herbicide containing 2,4-dichlorophenoxyacetic acid and picloram, in the drinking water for 15 w at concentrations ranging from 0 to 0.3% of the product formulation. After 3 w of the 15-w treatment period, the mice received 1.5 mg/g urethan ip. Pulmonary adenoma production was evaluated 12 w later. Tordon 202c exposure produced a dose-dependent increase in tumor number, but had no effect on tumor size. Urethan-induced sleeping times which reflected the rate of urethan metabolism or excretion were altered, but a specific dose-related effect which could be correlated with tumor production was not observed. This suggests that Tordon 202c exposure influences adenoma formation by immunological mechanisms rather than by causing indirect effects on urethan metabolism or excretion.

2,4-Dichlorophenoxyacetic Acid↗

PubMedDate not supplied

Gas chromatographic determination of N-nitrosodialkanolamines in herbicide Di- or trialkanolamine formulations.

A modified method is presented to determine trace quantities of N-nitrosodiethanolamine (NDElA) and N-nitrosodiisopropanolamine (NDiPlA) in the triisopropanolamine (TiPlA) formulation of a mixture of picloram and 2,4-D. Aqueous sample is extracted with dichloromethane to remove organic interferences, and then the aqueous layer is passed sequentially through chloride anion exchange column, hydrogen cation exchange column, and Clin-Elut extraction tube. The final eluate, 10% acetone in ethyl acetate, is concentrated. The isolated nitrosamines are converted to the corresponding trimethylsilyl (TMS) derivatives and determined by gas chromatography (GC) on a DB1 column coupled with a thermal energy analyzer (GC-TEA). Eight samples of commercial TiPlA formulations are analyzed. Maximum detected levels of NDElA and NDiPlA were 0.6 and 0.9 ppm, respectively, expressed relative to total weight of active ingredients. Analysis of 13 samples of herbicide DElA formulation using a previously established method and a DB225 column gave NDElA results of 0.7-6.0 ppm. NDiPlA was not detected in those samples. Results are confirmed by GC-mass spectrometry (GC/MS) with oxygen negative chemical ionization (ONCI) detection. Detection limits for both nitrosamines are 0.05 or 0.07 ng (0.1 or 0.17 ppm) for GC-TEA detection, depending on the analytical columns used, and 20 pg (0.04 ppm) for GC/MS detection. Recoveries of NDElA are 87-109% for DElA formulation spiked at 2.6 and 3.9 ppm and 90-115% for TiPlA formulation spiked at 0.2-0.3 ppm. Similarly, recoveries of NDiPlA are 95.7-100% for the DElA formulation spiked at 0.24 and 0.48 ppm, and 82-118% for the TiPlA formulation spiked at 0.2-0.3 ppm.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1997

Effect of roundup and tordon 202C herbicides on antibody production in mice.

Female CD-1 mice were exposed to Tordon 202C (2,4-dichlorophenoxyacetic acid [2,4-D] and picloram) or Roundup (glyphosate) in drinking water for 26 d at concentrations ranging from 0 to 0.42% or from 0 to 1.05%, respectively. The mice were inoculated with sheep red blood cells to produce a T-lymphocyte, macrophage dependent antibody response on day 21 of the herbicide exposure period. Tordon 202C dosing reduced weight gain and water consumption at the 0.42% level of exposure. Roundup exposure did not alter weight gain or water consumption. Antibody production was unaffected by Roundup dosing, suggesting that Roundup is unlikely to cause immune dysfunction under normal application conditions. In contrast, all levels of Tordon 202C exposure reduced antibody production by as much as 45%. The immunosuppressive activity of Tordon 202C was associated with levels more than 12 x the normal application level, although it was not determined which component of the formulation was responsible for the immunosuppression effect. The presence of immune alteration subsequent to exposure to Tordon 202C at levels marginally above the normal application levels suggests that chronic exposure to Tordon 202C in the environment has the potential to alter immune function.

2,4-Dichlorophenoxyacetic Acid↗

PubMedDate not supplied

Development of California Public Health Goals (PHGs) for chemicals in drinking water.

As part of a program for evaluation of environmental contaminants in drinking water, risk assessments are being conducted to develop Public Health Goals (PHGs) for chemicals in drinking water, based solely on public health considerations. California's Safe Drinking Water Act of 1996 mandated the development of PHGs for over 80 chemicals by 31 December 1999. The law allowed these levels to be set higher or lower than federal maximum contaminant levels (MCLs), including a level of zero if data are insufficient to determine a specific level. The estimated safe levels and toxicological rationale for the first 26 of these chemicals are described here. The chemicals include alachlor, antimony, benzo[a]pyrene, chlordane, copper, cyanide, dalapon, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 2,4-D, diethylhexylphthalate, dinoseb, endothall, ethylbenzene, fluoride, glyphosate, lead, nitrate, nitrite, oxamyl, pentachlorophenol, picloram, trichlorofluoromethane, trichlorotrifluoroethane, uranium and xylene(s). These risk assessments are to be considered by the State of California in revising and developing state MCLs for chemicals in drinking water (which must not exceed federal MCLs). The estimates are also notable for incorporation or consideration of newer guidelines and principles for risk assessment extrapolations.

Algorithms↗

PubMed1983

Pesticide-induced complete and partial chromosome loss in screens with repair-defective females of Drosophila melanogaster.

Commercial preparation of fungicides (captan and maneb), herbicides (bromacil, paraquat, picloram, and 2,4-D), and insecticides (carbaryl, chlorpyrifos, dimethoate, DDT, diazinon, carbofuran, and permethrin) were tested for their ability to induce complete and partial chromosome losses in Drosophila melanogaster males. In an attempt to identify the mutagenic activity of pesticides that are toxic in low concentrations in Drosophila, these males were mated with mus-302 repair-defective females. The rationale for this mating scheme is based on the repair of genetic damage in Drosophila sperm by maternal enzymes in the zygote, and on the reports that there may be increases in the frequency of recovery of chemically induced chromosome losses in crosses of treated males with mus-302 females. Verification of the sensitivity of this screen in this study came from significant increases in the frequency of chromosome loss induced by low concentrations of the positive controls, N-nitrosodimethylamine and methyl methanesulfonate. Of the 13 pesticides, the insecticide chlorpyrifos induced a significant amount of ring-X chromosome loss. No pesticide induced a significant increase in partial chromosome loss. These results are discussed in relation to the usefulness of repair-defective mutants in screens for genetic damage in Drosophila and other higher eukaryotes by chemicals that are toxic or cause sterility at low concentrations.

Animals↗

PubMed2002

On the mechanism of selectivity of the corn herbicide BAS 662H: a combination of the novel auxin transport inhibitor diflufenzopyr and the auxin herbicide dicamba.

BAS 662H, a 1:2.5 combination of the semicarbazone-type auxin transport inhibitor diflufenzopyr and the auxin herbicide dicamba, is used as a post-emergence herbicide in corn. The combination has been observed to provide more effective broadleaf weed control and improved tolerance in corn than typical rates of dicamba used alone. In order to analyze this phenomenon, the uptake, translocation, metabolism and action of both compounds, applied alone and in combination, were investigated in Amaranthus retroflexus L, Galium aparine L and corn (Zea mays L). When plants at the third-leaf stage were foliarly treated with diflufenzopyr and dicamba equivalent to field rates of 100 and 250 gha-1, respectively, diflufenzopyr synergistically increased dicamba-induced 1-aminocyclopropane-1-carboxylic acid (ACC) synthase activity and ethylene formation in G aparine and even more in A retroflexus, followed by accumulations of (+)-abscisic acid (ABA) in the shoot tissue within 20 h. This correlated with subsequent growth inhibition, hydrogen peroxide overproduction and progressive tissue damage. Diflufenzopyr also enhanced the activity of other auxin herbicides, such as quinclorac and picloram, and of the synthetic auxin, 1-naphthaleneacetic acid. After foliar and root application of [14C]diflufenzopyr, alone or as BAS 662H, considerably lower tissue concentrations and systemic translocation of radioactivity beyond treated plant parts were found in corn, compared to G aparine and particularly A retroflexus. Furthermore, diflufenzopyr decreased foliar uptake of [14C]dicamba by c 50% selectively in corn, compared to the treatment alone. Metabolism of [14C]diflufenzopyr was more rapid in corn than in the weed species. In combination, the two compounds had no mutual effect on their metabolic degradation. In BAS 662H, diflufenzopyr synergizes the herbicidal activity of dicamba in sensitive weed species. In corn this effect is prevented by a more rapid metabolism of diflufenzopyr, coupled with lower uptake and translocation. Selectivity of BAS 662H is additionally favoured by a higher crop tolerance to dicamba because of reduced foliar uptake of this herbicide in corn under the influence of diflufenzopyr.

Abscisic Acid↗

PubMed1999

Effects of organic pollutants on soil microbial activity: the influence of sorption, solubility, and speciation.

The Fe(III) reduction test was used to measure the toxicity of 12 organic chemicals [dichlorophenoxyacetic acid (2,4-D), trichlorophenoxyacetic acid (2,4,5-T), atrazine, picloram, 4-chlorobenzeneamine, pentachlorophenol (PCP), hexachlorobenzene (HCB), 1,1-bis-4-chlorophenyl-2,2,2-trichloroethane (DDT), trichloroethene, benzene, phenol, linear alkylbenzenesulfonate (LAS)]. The different inherent toxicity of the pollutants is strongly modified by interactions with the soils. The total amounts that cause 10, 50, and 90% inhibitions (effective doses, ED10, ED50, ED90) can be statistically related to soil parameters that control the sorption and solubility of the chemicals. Sorption experiments with 2,4-D, 2,4,5-T, PCP, and LAS confirm that the degree of sorption and the concentration in the soil solution are important for potential toxic effects. However, toxic solution concentrations of a chemical (effective concentrations, EC10, EC50, EC90) also vary considerably. For some chemicals the influence of soil pH on their speciation in the soil solution is mainly responsible for this, e.g., the transformation from anionic to nonionic species with decreasing pH. The nonionic species of 2,4-D, 2,4,5-T, and PCP formed under acidic conditions are more toxic than the anionic species. Thus, depending on the chemical parameters of the soils that determine the degree of sorption and the speciation of toxicants in the liquid phase, soils either can "buffer" high loads of toxicants or can be very sensitive toward contamination.

Dose-Response Relationship, Drug↗

PubMed1976

Some patterns of herbicide and growth regulator intake, persistence, and distribution in sugarcane.

Absorption of 14C-labeled herbicides from nutrient culture solution through the roots of sugarcane plants (Saccharum spp. hybrids) resulted in three major types of distribution. Labeled residues from atrazine, ametryne, and metribuzine moved easily through the xylem to the green leaves and were deposited mainly at the leaf margins and tip. Senescence and leaf abscission removed most of the deposit from the plant. Picloram translocated rapidly into the leaves, but appeared to recycle from older to younger leaves with only small portions remaining in the senescent leaves. Asulam and pentachlorophenol (PCP) were absorbed by the roots; residues did not pass into the xylem and remained fixed in the roots. Foliar additions of labeled herbicides and growth regulators generally showed only minor absorption and translocation within the leaf. Weathering processes and volatility during a 6- to 12-week period left variable amounts of residue, characteristic of individual compounds, absorbed at the treated sites.

Absorption↗

PubMed2004

Agrobacterium-mediated transformation of the wetland monocot Typha latifolia L. (Broadleaf cattail).

An Agrobacterium-mediated model transformation system was standardized for the wetland monocot Typha latifolia L. to achieve the long-term objective of introducing candidate genes for phytoremediation. Two binary plasmid vectors, pCAMBIA1301/EHA105 and pTOK233/LBA4404, both containing the gus (beta-glucuronidase) and hptII (hygromycin phosphotransferase II) genes, were used for transformation. Fifty-day-old 5 mg/l picloram-derived calli were cocultivated and selected on medium containing 20 mg/l or 40 mg/l hygromycin. Resistant calli were regenerated on medium supplemented with 5 mg/l 6-benzylaminopurine, with or without 20 mg/l or 40 mg/l hygromycin and with or without charcoal (10 g/l). Transient GUS activity in explants ranged between 28% and 36%. Hygromycin-resistant calli, selected after 3 months, showed stable GUS expression. A total of 46 plants were regenerated and established in the greenhouse; 13 showed stable GUS expression. Cocultivation of dark culture-derived calli, directly selected on regeneration medium containing 20 mg/l hygromycin and rooted on medium with 20 mg/l hygromycin was the best protocol. The addition of charcoal did not have any effect on regeneration. PCR and Southern analyses of transgenic calli and transgenic plants confirmed the presence of the introduced genes. In conclusion, T. latifolia could be genetically transformed by Agrobacterium tumefaciens.

Blotting, Southern↗