Rates Of Herbicide Metabolism Research Articles

JoVE - Year in Review: 2015

In January 2015, JoVE Developmental Biology became the newest addition to the JoVE family, and featured a live-imaging protocol for visualizing the developing Drosophila eye. In February, JoVE Medicine showed state-of-the-art cranial ultrasound imaging in neonates. Advances in this technique have improved its diagnostic value, allowing timely therapeutic intervention. In March, JoVE Environment featured dendroecology, the science of using tree rings to study ecological effects of specific environmental factors. In April, JoVE Biology examined a mode of bacterial motility called swarming with a two-phase swarm assay. that can be used to study various aspects of bacterial growth. In May, JoVE Chemistry described the self-assembly of single-stranded DNA tiles into complex 2D shapes. This demonstrated the principles of DNA tiling as an approach for making programmable nanostructures. June 2015 marked the release of JoVE's 100th issue, and in JoVE Behavior, we featured protocols for assessing cognition, including a method of quantifying learning in young infants by tracking leg movements. In July, JoVE Medicine presented a method for measuring halitosis in dogs by taking breath samples, and performing gas chromatography. This assay could be used in trials of dog food formulated to fight bad breath in our canine companions. In August, JoVE Bioengineering contained a protocol for bioengineering kidney tissues. Kidneys are decellularized by perfusion, and repopulated with human renal cells, This promising technology can lead to kidney grafts made from a patient's own cells. In September, JoVE Environment examined herbicide resistance, which threatens commercial crop production. An excised leaf assay determines the rates of herbicide metabolism, which is useful for studying the metabolic basis of resistance. In October, JoVE Neuroscience featured a method for interfacing 3D neuronal cultures to micro-electrode arrays. The complex 3D assemblies closely approximate in vivo neural networks. November's edition of JoVE Behavior showcased the natural human ability to acquire new motor skills, which is central in a structured rehabilitation program for amputees as they learn how to use multifunctional prosthetics. In December, JoVE Immunology & Infection prepared us for the impending flu season with an easy protocol for sampling influenza in pigs. Because swine are important hosts for flu viruses, this method helps to monitor virus evolution and currently circulating strains. This Year in Review was just a sampling of more than 900 video-articles that JoVE published in 2015. Browse the JoVE archives for thousands of other videos, and come back each week to see brand-new material in JoVE: The Journal of Visualized Experiments.

September 2015 - This Month in JoVE: Measuring Greenhouse Gases and Herbicide Resistance, Bioengineering Bone, and Analyzing Neuromuscular Control with Virtual Reality

Here's a look at what's coming up in the September 2015 issue of JoVE: The Journal of Visualized Experiments. In JoVE Environment, we've had a pretty warm summer in the northern hemisphere, so we can't help but think about all the greenhouse gases in our atmosphere that keep our planet nice and warm. These days, livestock are a major source of greenhouse gas emissions, especially methane. Livestock contribute anywhere from 7 to 18% of global emissions-depending on who you ask. Naturally, climate scientists are interested in controlling enteric methane from livestock. This requires accurate and precise measurement techniques, so Hristov et al. present a method using the Automated Head-Chamber System (AHCS), which monitors methane (CH4) and carbon dioxide (CO2) mass fluxes from the breath of ruminant animals (e.g., cattle). This system produces repeatable and accurate emission results, and can help efforts to curb greenhouse gas emissions. In JoVE Environment, we're also concerned about herbicide resistance in weeds, which poses a serious threat to food and fiber production. Plants can gain resistance to herbicides through genetic mutations or through enhanced activity of enzymes that metabolize and detoxify chemicals. In order to determine rates of herbicide metabolism in certain weeds, Ma et al. developed an excised leaf assay, which allows them to take experiments from the greenhouse into the lab so they can perform radiolabeled herbicide experiments more efficiently. As more and more plants become resistant to herbicides, this method will be useful for investigating the metabolic basis of herbicide resistance. In JoVE Bioengineering, one of the ultimate goals of tissue engineering is to regenerate large bone defects using synthetic scaffolds or templates. Most available scaffolds don't allow appreciable cell infiltration or distribution to achieve significant bone regeneration, so Oh et al. have developed a highly porous bone-like template with micro-channels and nanopores. Cells can be seeded into the biogenic templates through capillary action, and grow to confluence within days. This concept can help advance the repair of large bone defects. In JoVE Behavior, the human neuromuscular junction can be studied using a variety of noninvasive techniques, including electromyography (EMG), 3D motion capture, and transcranial magnetic stimulation. This month, Talkington et al. add the unique aspect of virtual reality to this test battery, and describe a customizable circuit that synchronizes data sampled from all of these techniques. You've just had a sneak peek of the September 2015 issue of JoVE. Visit the website to see the full-length articles, plus many more, in JoVE: The Journal of Visualized Experiments.

Late Watergrass (Echinochloa phyllopogon): Mechanisms Involved in the Resistance to Fenoxaprop-p-ethyl

Fenoxaprop-p-ethyl (FE), 2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy] propanoate, ethyl ester (R), is an aryloxyphenoxypropionate herbicide for postemergence control of annual and perennial grasses in paddy fields; its site of action is acetyl-coenzyme A carboxylase (ACCase), an enzyme in fatty acids biosynthesis. The possible mechanism(s) of resistance to FE in a resistant biotype of Echinochloa phyllopogon was examined, namely, absorption, translocation, and metabolism of FE and ACCase susceptibility to fenoxaprop acid (FA). Studies of the in vitro inhibition of ACCase discounted any differential active site sensitivity as the basis of resistance to FE. There were differences in absorption rates between biotypes from 3 to 48 h after application (HAA). Biotypes did not differ in either the amounts or the rates of FE translocated; 98% of applied [14C]FE remaining in the treated leaf. However, there was a good correlation between the rate of herbicide metabolism and the plant resistance. The R biotype produced 5-fold less FA and approximately 2-fold more nontoxic (polar) metabolites 48 HAA than the S biotype. Moreover, the higher rate of GSH conjugation in the resistant biotype as compared to the susceptible one indicates that GSH and cysteine conjugation is the major mechanism of resistance of the R biotype against FE toxicity.

Reduced rates of herbicide metabolism confer tri‐allate resistance in Avena fatua

Reduced rates of herbicide metabolism confer tri‐allate resistance in Avena fatua

Reduced rates of herbicide metabolism confer tri-allate resistance inAvena fatua

Reduced rates of herbicide metabolism confer tri-allate resistance in<i>Avena fatua</i>

Studies on the mechanism of selectivity of the auxin herbicide quinmerac

Investigations were conducted to elucidate the mechanism of selectivity of the auxin herbicide, quinmerac, in cleavers (Galium aparine) and the tolerant crops sugarbeet (Beta vulgaris), oilseed rape (Brassica napus) and wheat (Triticum aestivum). After root treatment with the herbicide, the selectivity has been quantified as approximately 400-fold between oilseed rape and Galium and 1000-fold between sugarbeet or wheat and the weed species. When 1 and 10 μM [ 14 C]quinmerac were applied for 4 h, no significant differences between root absorption and translocation of 14 C by Galium and the crop species were found. After 16 h, metabolism of [ 14 C]quinmerac to the biologically inactive hydroxymethyl and dicarboxylic acid derivatives was more rapid in wheat and sugarbeet than in Galium. In oilseed rape, a lower rate of herbicide metabolism was observed. In Galium, accumulations of abscisic acid (ABA), triggered by quinmerac-stimulated ethylene biosynthesis, were found to cause the herbicidal growth inhibition which develops during 24 h of application. Within 1 h of treatment, quinmerac stimulated 1-aminocyclopropane-1-carboxylic acid (ACC) synthase activity and ACC concentration specifically in Galium shoot tissue. During the next 4 h, ACC synthase activity was increased up to 50-fold, relative to the control. Within 3 h of exposure to quinmerac, increased ethylene formation followed by higher ABA levels was detected. In sugarbeet, oilseed rape and wheat, quinmerac did not stimulate ACC synthase activity and ACC and ABA levels. It is suggested that (i) the selectivity of quinmerac is primarily based upon the lower sensitivity to the herbicide of the tissue/target in the crop species, (ii) the induction process of the ACC synthase activity in the shoot tissue is the primary target of herbicidal interference. In wheat and sugarbeet, tolerance to quinmerac is additionally increased by a more rapid metabolism.

Herbicide-insecticide interaction in maize: Malathion inhibits cytochrome P450-dependent primisulfuron metabolism

Tolerance of maize to sulfonylurea herbicides such as primisulfuron has recently been reported to be impaired by the use of some organophosphorus insecticides. In an effort to elucidate the mechanism of this interaction, the effect of the insecticide, malathion, on the metabolism of primisulfuron was studied in whole plants, in excised leaves, and in a microsomal in vitro system from maize. Foliar application of malathion to 7-day-old plants had no influence on leaf uptake and translocation of primisulfuron, but caused a decrease in the rate of herbicide metabolism. In excised leaves, malathion increased the metabolic half-life of primisulfuron. In microsomal preparations, malathion inhibited cytochrome P450-dependent primisulfuron phenyl- and pyrimidinering hydroxylation. Loss of primisulfuron phenyl-ring hydroxylase activity was time-dependent, saturable with respect to malathion concentration, and attenuated in the absence of NADPH. The kinetic data suggest a mechanism-based cytochrome P450 inactivation by malathion. The oxoanalogue of malathion, malaoxon, did not influence the metabolic half-life of primisulfuron in excised leaves and was a poor inhibitor of microsomal primisulfuron hydroxylation. Neither insecticide had any effect in vitro on total microsomal cytochrome P450 content. From the present results it may be concluded that malathion affects primisulfuron tolerance of maize due to the inhibition of cytochrome P450 monooxygenases involved in herbicide metabolism.

The Effect of BAS 145138 Safener on Chlorimuron Ethyl Metabolism and Toxicity in Corn

Abstract BAS 145138 was moderately effective in protecting corn from injury due to chlorimuron ethyl. BAS 145138 increased the I50 of chlorimuron ethyl to corn, determined by root-growth in a sandy loam soil, from 6 g chlorimuron ethyl/ha to 25 g/ha. BAS 145138 caused an increase in the rate of chlorimuron ethyl metabolism , but it did not effect the rate of chlorimuron ethyl uptake or the nature of the metabolites produced. Major metabolites included chlorimuron ethyl hydroxylated in the pyrimidine ring (hydroxychlorimuron ethyl), the glucoside of hydroxychlorimuron ethyl, the glutathione conjugate formed by displacement of chlorine, a metabolite characterized as the glutathione conjugate sulfoxide or a hydroxylated glutathione conjugate, four unidentified polar metabolites, and 2-sulfonylamino benzoic acid ethyl ester. Metabolites were characterized by mass spectrometry and hydrolysis. It was concluded that BAS 145138 partially protects corn from chlorimuron ethyl by causing an increase in the rate of herbicide metabolism by hydroxylation, glucoside conjugation and by glutathione conjugation.