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At least 253 records · Page 14Linked to original sources
PubMed1992

Effects of nitrite, chlorate, and chlorite on nitrate uptake and nitrate reductase activity.

Effects of NO(2) (-), ClO(3) (-), and ClO(2) (-) on the induction of nitrate transport and nitrate reductase activity (NRA) as well as their effects on NO(3) (-) influx into roots of intact barley (Hordeum vulgare cv Klondike) seedlings were investigated. A 24-h pretreatment with 0.1 mol m(-3) NO(2) (-) fully induced NO(3) (-) transport but failed to induce NRA. Similar pretreatments with ClO(3) (-) and ClO(2) (-) induced neither NO(3) (-) transport nor NRA. Net ClO(3) (-) uptake was induced by NO(3) (-) but not by ClO(3) (-) itself, indicating that NO(3) (-) and ClO(3) (-) transport occur via the NO(3) (-) carrier. At the uptake step, NO(2) (-) and ClO(2) (-) strongly inhibited NO(3) (-) influx; the former exhibited classical competitive kinetics, whereas the latter exhibited complex mixed-type kinetics. ClO(3) (-) proved to be a weak inhibitor of NO(3) (-) influx (K(i) = 16 mol m(-3)) in a noncompetitive manner. The implications of these findings are discussed in the context of the suitability of these NO(3) (-) analogs as screening agents for the isolation of mutants defective in NO(3) (-) transport.

Journal Article↗
PubMed1983

Soybean Mutants Lacking Constitutive Nitrate Reductase Activity : II. Nitrogen Assimilation, Chlorate Resistance, and Inheritance.

Nitrogen assimilation in three nitrate reductase (NR) mutants of soybean (Glycine max L. Merr. cv Williams) was studied in the growth chamber and in the field. These mutants, LNR-2, LNR-3, and LNR-4, lack the non-NO(3) (-)-inducible or constitutive fraction of leaf NR activity found in wild-type plants, but this had no effect on the concentration of nitrogen accumulated when grown on NO(3) (-) in the growth chamber. Dry weight accumulation of two of the mutants (LNR-3 and LNR-4) was decreased relative to LNR-2 and wild type. In the field, LNR-2 had dry weights and nitrogen concentrations similar to the wild type at 34 and 61 days after planting, and at maturity. Acetylene reduction activities were also similar at 61 days.Urea-grown LNR-2 seedlings lack both inducible and constitutive NR activity, and were resistant to four days of treatment with 0.5 mm ClO(3) (-). Urea-grown wild-type seedlings, having only constitutive NR activity, developed ClO(3) (-) toxicity symptoms and suffered decreases in unifoliolate leaf NR activity and chlorophyll concentration. This suggests that (a) the reduction of ClO(3) (-) to ClO(2) (-) by NR is the major cause of ClO(3) (-) toxicity in soybeans and (b) the constitutive NR is active in situ.Segregation of the F(2) of reciprocal crosses between the wild type and the mutants indicated that absence of constitutive NR activity was controlled by a single recessive nuclear gene. Evolution of NO((x)) gas was also absent in these mutants, and this was found to be inherited jointly with constitutive NR activity: in 346 segregants, no recombinants were found. Allelism tests between LNR-2 and LNR-3, and LNR-2 and LNR-4, indicated that the constitutive NR mutation was at the same locus in each mutant.

Journal Article↗
PubMed1982

Toxicological effects of chlorine dioxide, chlorite and chlorate.

Review of the available literature obtained from both acute and chronic experiments utilizing rats, mice and chickens treated with ClO2, ClO2- and ClO3-in drinking water has demonstrated alterations in hematologic parameters in all species tested. The effects were usually dose related and marked changes occurred only at the higher dosages (up to 1000 mg/l.). In chronic studies, rats have been given ClO2 at doses of up to 1000 mg/l., and NaClO2 or NaClO3 at up to 100 mg/l., in their drinking water for one year. Treatment groups receiving ClO2, ClO2- or ClO3- showed alterations in erythrocyte morphology and osmotic fragility; at higher dosages mild hemolytic anemia occurred. An examination of blood glutathione content and RBC enzymes involving glutathione formation showed a dose-related diminution of glutathione in chlorine compound treated groups. The higher oxidative capacity of the chlorine compounds resulting in the decreased erythrocytic glutathione might well be the principal biochemical event leading to the other hematological alterations. More recent data show that ClO2, ClO2- and ClO3- alter the incorporation of 3H-thymidine into the nuclei of various organs of the rat. These data suggest the possibility of increased turnover cells of the gastrointestinal mucosa and inhibited DNA synthesis in several organs. In the latter category, most concern revolves around whether or not the apparent depression of DNA synthesis in the testes is associated with depressed spermatogenesis and reproductive toxicity in the male rat.

Animals↗
PubMedDate not supplied

[Preliminary research on the chlorate insecticides and phosphoric esters content in some italian boneys. (author's transl)].

The author shows the results of a research on chlorine-organic pesticides and phosphoric esters content of some Italian honeys. Of 12 insecticides investigated, only 7 are resulted present in measurable quantities and their concentration has been revealed always modest; therefore the risk of pollution is very small. In any case the main object of this research was to set up a method of identification and dosage of the pesticides and to show its validity.

Honey↗