Uptake and translocation

Biorational approaches have proven useful in the development of classes of herbicides which inhibit essential metaboHc pathways common to all plants and thus are specific to plants and have low toxicity to mammalian species. Biorational herbicide development remains a high risk endeavor since promising high activities observed in the laboratory may be nullified by factors such as limitations in plant uptake and translocation, and the instabiHty or inactivity of biochemical en2yme inhibitors under the harsher environmental conditions in the field. Despite these recogni2ed drawbacks, biorational design of herbicides has shown sufficient potential to make the study of herbicide modes of action an important and growing research area. 

Plant uptake is one of several routes by which an organic contaminant can enter man s food chain. The amount of uptake depends on plant species, concentration, depth of placement, soil type, temperature, moisture, and many other parameters. Translocation of the absorbed material into various plant parts will determine the degree of man s exposure—i.e., whether the material moves to an edible portion of the plant. Past experience with nonpolar chlorinated pesticides suggested optimal uptake conditions are achieved when the chemical is placed in a soil with low adsorptive capacity e.g., a sand), evenly distributed throughout the soil profile, and with oil producing plants. Plant experiments were conducted with one set of parameters that would be optimal for uptake and translocation. The uptake of two dioxins and one phenol (2,4-dichlorophenol (DCP)) from one soil was measured in soybean and oats (7). The application rates were DCP = 0.07 ppm, DCDD 0.10 ppm, and TCDD = 0.06 ppm. The specific activity of the com-... 

Mahon DC. 1982. Uptake and translocation of naturally-occurring radionuclides of the uranium series. Bull Environ Contain Toxicol 29(6) 697-703. 

Briggs, G.G., Bromilow, R.H. and Evans, A.A., Relationships between lipophilicity and root uptake and translocation of non-ionized chemicals by barley, Pestic. Sci., 13, 495-504, 1982. 

Lead may be taken up in edible plants from the soil via the root system, by direct foliar uptake and translocation within the plant, and by surface deposition of particulate matter. The amount of lead in soil that is bioavailable to a vegetable plant depends on factors such as cation exchange capacity, pH, amount of organic matter present, soil moisture content, and the type of amendments added to the soil. Back-... 

Huang J.W., Cunningham S.D. Lead phytoextraction Species variation in lead uptake and translocation. NewPhytol 1996 134 75-84. 

Jani, P. et al., The Uptake and Translocation of Latex Nanospheres and Microspheres after Oral-Administration to Rats, Journal of Pharmacy and Pharmacology. 41, 809, 1989. 

The size of the nanomaterial greatly influences its toxicity particularly as the nanomaterial s size decreases, certain of its parameters changed [3, 11, 118, 119]. Many studies have shown that variations in the size of nanomaterials account for the different toxicity levels between nanosized and micrometer-sized materials [97, 99,100,103], It is known that a reduction in size can increase the rate of uptake and translocation of silica nanomaterials in vitro and in vivo, thereby inducing a more severe and transient toxicity [56]. 

Uptake and translocation of radionuclides under hydroponic and in vitro conditions... 

Autoradiography allows the localization of radionuclide within plant tissue, which is important for an understanding of the uptake and translocation mechanisms. It also represents a selection method for the efficiency... 

Chou SF, Jacobs LW, Penner, D, et al. 1978. Absence of plant uptake and translocation of polybrominated biphenyls (PBBs). Environ Health Perspec 23 9-12. 

Jani, P., Halbert, G. W., Langridge, J.,and Florence, T. The uptake and translocation of latex nanospheres and microspheres after oral administration to rats. J. Pharm. Pharmacol. 41 809-812, 1989. 

Figure 8. Uptake and translocation of radioactivity in spring barley after treating the upper side of the lower third of the leaf, including the leaf sheath, with [ 4C]triadimefon (macroautoradiographic radioactivity detection). (Reproduced with permission from Ref. 19. Copyright 1978 Pflanzenschutz-Nachrichten Bayer.)...

Staub, T., Dahmen, H. and Schwinn, F.J. 1978. Biological characterization of uptake and translocation of fungicidal acylalanines in grape and tomato plants. Z. Pflanzenkr. Pflan-zenschutz 85, 162-168. 

Hinman, M.L., Klaine, S.J. (1992) Uptake and translocation of selected organic pesticides by the rooted aquatic plant Hydrilla verticillata royale. Environ. Sci. Technol. 26, 609-613. 

Takahashi, M., Kawamura, S., Miyakado, M., Sanemitsu, Y., Tanaka, S. (1993) Uptake and translocation of bleaching herbicidal compounds in radish seedlings. Pestic. Sci. 39, 159-177. 

Trapp, St., Pussemier, L. (1991) Model calculations and measurements of uptake and translocation of carbamates by bean plants. Chemosphere 22, 327-339. 

The Peyer s patches are found particularly in the distal ileum of the intestinal tract. The epithelium covering the Peyer s patches comprises specialized antigen-presenting epithelial cells, called M-cells (modified epithelial cells). This lymphoid tissue plays an important part in the body s immune system, as it samples antigenic material entering the GI tract and mounts an immune response as appropriate. The uptake and translocation of antigen by the M-cells of Peyer s patches can be exploited for oral drug and vaccine delivery, as described below (Section 6.7.7). 

There are two possible sources of PCDD/Fs to vegetation the atmosphere and soil. Initially it was thought that PCDD/Fs would not be present in the atmosphere in quantities sufficient to contaminate plants owing to their low volatility, and early research in this area focused on uptake from soil. There are three possible pathways of soil-bound PCDD/Fs to aerial plant parts root uptake and translocation, volatilization followed by adsorption to foliage, and transfer of soil particles (see Figure 1). The first of these pathways has received the most attention. 

Experiments were conducted to determine how quickly a low concentration (1.4 /zM) of an aryloxyphenoxypropanoate, haloxyfop (2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]-propanoic acid) (Fig.l) could affect lipid metabolism. We used leaf discs as experimental material because it would mitigate effects of herbicide uptake and translocation. Maize (Zea mays) leaf discs were prepared as previously described (15) and incubated in C-acetate. At various times, discs were removed and cell constituents were separated into organic and aqueous soluble fractions (16). Within 30 min of application, 1.4 /zM of either the free acid or the methyl ester of haloxyfop inhibited lipid... 

Arvy, M.P. 1993. Selenate and selenite uptake and translocation in bean plants (Phaseolus vulgaris). Journal of Experimental Botany, 44 1083-7. 

Fig. 3.3. Uptake and translocation patterns of Fe in the presence or absence of arbuscular mycorrhizas (AM), and with or without iron fertilization of soil, to peanut or sorghum plants, (a) Experimental...

Gray, S. N., Dighton, J., Olsson, S. Jennings, D. H. (1995). Real-time measurement of uptake and translocation of 137Cs within mycelium of Schizophyllum commune Fr by autoradiography followed by quantitative image-analysis. New Phytologist, 129, 449-65. 

Rufyikiri, G., Thiry, Y. Declerck, S. (2003). Contribution of hyphae and roots to uranium uptake and translocation by arbuscular mycorrhizal carrot roots under root-organ culture conditions. New Phytologist, 158, 391-9. 

Cord development is triggered not only by connection between resources, but also by the nutrient status of the mycelium. Developmental responses in saprotrophic cord formers may be caused by the changes in C/N balance in individual hyphae resulting from a local rise in nutrient levels due to uptake and translocation of nutrients within some hyphae but not others. Development and biomass production are differentially affected by carbon and nitrogen content and the C/N ratio in defined media (Watkinson, 1999 Fig. 7.4). Biomass increased with both sucrose and aspartate, while... 

Ma, J. F. Hiradate, S. (2000). Form of aluminium for uptake and translocation in buckwheat (Fagopyrum esculentum Moench). Planta, 211, 355-60. 

Figure 2. Three-phase-process of auxin herbicide action exemplified for the dicot weed Galium aparine after root-uptake and translocation in the plant (shown in autoradiographs using labelled compound).

The study of the efficacy and behaviour of different products and their formulations has evolved through purely empirical field trials, into various controlled environment or laboratory screening methods, to more detailed fundamental and mechanistic studies, leading to the development of models for the processes of deposition, retention, uptake and translocation [3]. This overview will consider these processes, their limitations, and their future potential. Due to the fact that most studies have been with herbicides into plants, with little or no information on uptake of pesticides by insects or padiogens, the main focus will be on the uptake of herbicides into plant foliage. 

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