Uptake Of Paraquat Research Articles

A New Species of Torrubiella on a Spider from the Falkland Islands

1. Brown, C. L., and L. E. Nix. 1975. Uptake and transport of paraquat in slash Ipine. Forest Sci. 21: 359-364. 2. Caulderbank, A. 1968. The bipyridylium herbicides. Advances Pest Control Res. 8: 127-236. 3. Lawlor, D. W. 1970. Absorption of polyethylene glycols by plants and their effects on plant growth. New Phytol. 69: 501-513. 4. Lindgren, R. M. 1942. Temperature, moisture, and penetration studies of wood-staining Ceratostomellae in relation to their control. USDA Techn. Bull. 807: 1-35. 5. Marx, D. H. 1969. The influence of ectotrophic mycorrhizal fungi on the resistance of pine roots to pathogenic infections. I. Antagonism of mycorrhizal fungi to root pathogenic fungi and soil bacteria. Phytopathology 59: 153-163. 6. Mexal, J., and C. P. P. Reid. 1973. The growth of selected mycorrhizal fungi in response to induced water stress. Canad. J. Bot. 51: 1579-1588. 7. Zak, B. 1972. Flotation of excised root and fungal cultures on liquid media. Canad. J. Microbiol. 18: 536-538.

The relationship between 5-hydroxytryptamine and paraquat accumulation into rat lung

The uptake of 5-hydroxytryptamine (5HT) into rat lung slices has been shown to obey saturation kinetics and to be inhibited by imipramine, metabolic inhibitors and a sodium-free medium. The apparent Km for the uptake process was found to be 3.3 μMwith a Vmax of 6 nmoles/g wet wt/min. Lung slices taken from rats given a dose of paraquat known to damage type I and type II lung epithelial cells showed inhibition of paraquat uptake but no inhibition of 5HT uptake. This together with the stimulation of paraquat accumulation into rat lung slices in a sodium-free medium leads to the conclusion that the uptake of paraquat and 5HT into the lung does not occur in the same cell type.

High uptake in the erythrocytes and the spleen of the quaternary dipyridylium salt paraquat injected intravenously in hypotonic solutions.

Intravenous injections of the quaternary dipyridlium salt paraquat (14C-labelled) dissolved in solutions of low tonicity result in a high uptake in the erythrocytes and concomitantly also in the spleen (red pulp), the latter being probably due to phagocytosis of paraquat-containing erythrocytes by the reticuloendothelial system. Higher tonicities of the injected solutions result in a low uptake and the same applies to oral, intraperitoneal and subcutaneous injections. Paraquat was present in the erythrocytes in a non-metabolized form without being bound to membranes or proteins. The uptake in the erythrocytes was not influenced by alterations of the pH or by the preparation of a charge-transfer complex with serotonin in the injection solutions. Chemical alterations of the paraquat in the injection solutions could not be detected. In vitro the uptake of paraquat in the erythrocytes was higher in the haemolysed (and then reconstituted by adding sodium chloride) erythrocyte-ghosts than in the non-haemolysed erythrocytes, as shown by incubations at various tonicities. It is proposed that the intravenous injections of paraquat in hypotonic solutions temporarily alter the membranes of the erythrocytes in the blood-stream and make them permeable to paraquat, possibly, as judged from the in vitro experiments, only during a short period of partial haemolysis. The distribution studies also showed a retention of paraquat in the lungs. In addition paraquat was accumulated in the melanin of the tissues.

Inhibition of paraquat accumulation in rat lung slices by a component of rat plasma and a variety of drugs and endogenous amines

The accumulation of paraquat by slices of rat lung has been shown to be inhibited in vitro by the addition of rat plasma. For a given concentration of plasma, inhibition was constant with time and the amount of inhibition increased with increasing concentration of plasma. This suggests that there are components of rat plasma which inhibit paraquat accumulation by rat lung slices in a concentration-dependent manner. An ultrafiltrate of plasma also inhibited paraquat uptake, indicating that the inhibitor is a small molecular weight compound. A number of endogenous amines including noradrenaline, 5-hydroxytryptamine and histamine have been shown to reduce the concentration of paraquat accumulated into lung slices, as have several other drugs including imipramine, propranalol, burimamide and betazole. The relevance of these findings to the prevention of paraquat accumulation by lung is discussed.

Uptake and Transport of Paraquat in Slash Pine

Uptake and Transport of Paraquat in Slash Pine

Fetal toxicity and distribution of paraquat and diquat in mice and rats

Administration of paraquat to mice, 1.67 and 3.35 mg/kg ip or 20 mg/kg po, daily on Days 8–16 of gestation induced no significant teratogenic effects, although a slight increase in nonossification of sternabrae was observed. Radioactivity reaching the mouse embryo after ip or po administration of [ 14C]paraquat on Day 11 of gestation was low. The fetal toxicity of diquat in rats, as measured by the number of dead and resorbing fetuses, was greater than that caused by paraquat after 15 mg/kg iv doses on various days of gestation, which correlated with higher fetal concentrations of [14C]diquat compared to [ 14C]paraquat. In perinatal organ distribution studies, more radioactivity from [ 14C]paraquat was retained in lung tissue of postnatal mice and rats than that in liver and kidney tissue. In prenatal studies, however, [ 14C]paraquat was retained in lung tissue of fetal rats after maternal administration of paraquat on Day 21 of gestation but not in lung tissue of fetal mice after maternal paraquat on Day 16 of gestation. This may be indicative of prenatal development of binding sites or of an active transport process for the uptake of paraquat into the lung or that elevated oxygen tensions in postnatal lungs contributes to paraquat retention in lung tissue.

Surfactants and the uptake and movement of paraquat in plants

AbstractSurfactants are still considered to be agents which either increase spray coverage of leaves with herbicidal solutions and/or increase herbicide penetration into the leaves. Experiments where the method of application largely eliminates leaf wetting as a factor in paraquat uptake show that this is an over‐simplification. Its efficiency in the plant is influenced by penetration and most of all by the degree of movement down the plant into untreated leaves. Results on the uptake, movement and biological activity of paraquat are reported using cocksfoot and wheat. A relation is found between paraquat movement and the hydrophilic nature of the surfactant. It moves most when the number of ethylene oxide residues is less than six and it is minimal when the number is 10 to 15. Leaf penetration, however, is at a maximum when movement under the influence of surfactant is least. Partition studies in which surfactants are distributed between leaf wax and water are described. There is a direct correlation between the degree of partition of the surfactant into the wax and the degree of movement of paraquat in cocksfoot and wheat. Surfactants are essential components of a paraquat formulation to wet the leaf surface and increase penetration but, when the surfactant also penetrates into the leaf, it reduces the mobility of paraquat and hence its efficiency.

The movement of paraquat as influenced by the partition coefficient of surfactants between water and leaf wax

Abstract“Lissapol” NX and “Lubrol” L, used to improve the uptake of paraquat into plants were found in earlier work to reduce its movement. Several series of surfactants with widely varying solubilities in water were partitioned between cabbage wax and water. A marked correlation was found between the effect of surfactants on the movement of paraquat and the amount of surfactant partitioning into the wax.It is concluded that although surfactants increase the uptake of paraquat into leaves, this increase is offset by reduced movement following penetration of surfactants into leaf tissue. Surfactant partition into wax reduces the degree of penetration, but there is no evidence how surfactants in leaf tissue reduce movement.

Uptake and movement of paraquat in cocksfoot and wheat as influenced by surfactants

AbstractSurfactants are used to increase the efficiency of herbicide formulations mainly because they wet out leaf surfaces, thereby stabilising and increasing the contact area of droplets on the surface. Herbicide penetration through the cuticle may also be facilitated.The work described eliminates effects on wetting and contact area in order to study the effect of surfactants on the penetration and movement of paraquat in cocksfoot. Surfactants were various types of alcohols and amine oxides condensed with 2 to 30 moles of ethylene oxide used at 0.1 to 0.5%. An adult leaf of cocksfoot (Dactylis glomerata) was immersed briefly to constant area in paraquat solutions containing surfactant and uptake and movement of paraquat is recorded.Uptake was little affected by differences in surfactant structure except where surface activity was low and solutions failed to wet out the leaf surface. Percentage movement with 0.5% surfactant was often less than that with 0.1% and a high ethylene oxide content also reduced percentage movement. Paraquat activity was influenced by both the degree of uptake and movement, but movement was the greater influence.Amine oxide surfactants reduced movement less than those based on alcohols. The action of surfactants is discussed in terms of a hydrophobic/hydrophilic balance in the surfactant molecule.

The influence of darkness on the uptake and movement of diquat and paraquat in tomatoes, sugar beet and potatoes

SUMMARYUptake of diquat and paraquat was doubled and occasionally quadrupled when tomatoes were darkened after treatment. The increase was not directly related to the duration of darkness because, after a time, uptake decreased. Three possible explanations for this decrease are considered, namely: diquat exudation from the leaves, downward movement into the roots and the complexing of diquat in plant tissue. Evidence was against exudation from leaves and downward movement into the roots.Diquat activity also depends on its degree of movement in the plant but the possible influence of other factors is discussed when treatments are made in the afternoon or in the morning after a period of reduced light intensity.In a CO2‐free atmosphere, uptake and activity increased in light and were comparable to those in darkness. Uptake is therefore not impeded by phyto‐toxic effects of diquat but possibly by the presence of a high concentration of solutes or by photosynthetic intermediates.

The uptake and adsorption of diquat and paraquat by tomato, sugar beet and cocksfoot

SUMMARYExperiments on leaves of tomato, sugar beet and cocksfoot show that uptake of diquat and paraquat, although rapid in the light, is increased by darkness and therefore takes place through the cuticle and not through stomata. Darkness for as little as 4 hr. increased uptake almost twofold.Diquat and paraquat are rapidly and strongly adsorbed both to leaf tissue and to extraneous matter on the leaf surface.Uptake in the field is so rapid that rain immediately after treatment has little adverse effect.