Response of Azospirillum brasilense Cd to sodium chloride stress.

Growth of Azospirillum brasilense Cd in the presence of different NaCl concentrations showed that it tolerates up to 200 mM NaCl in the medium, without appreciable decline in growth rate. At 300 mM NaCl, a decrease of 66% in growth was observed at 24 h of culture. At 48 h of culture, bacteria in the presence of 300 mM NaCl reached the maximum optical density value that was attained at 12 h by control cultures.

2,4-Dichlorophenoxyacetic acid affects the attachment of Azospirillum brasilense Cd to maize roots.

2.4-Dichlorophenoxyacetic acid (2,4-D) is a herbicide widely applied to forage, grain and cereals. We previously determined that 1 mM 2,4-D diminished cell growth and cellular activity of Azospirillum brasilense Cd.

Characterization of 2,4-dichlorophenoxyacetic acid transport and its relationship with polyamines in Azospirillum brasilense.

We have previously shown that 2,4-dichlorophenoxyacetic acid (2,4-D) inhibits Azospirillum brasilense growth, the synthesis of DNA, RNA and proteins. These toxic effects are prevented when polyamines are added to the culture medium. The purposes of our research were to determine the effects of the herbicide on the number of viable Azospirillum brasilense cells, characterize the 2,4-D transport system and to study the effects of polyamines upon the latter in this microorganism.

2,4-Dichlorophenoxyacetic acid influx is mediated by an active transport system in Chinese hamster ovary cells.

The influx of 2,4-dichlorophenoxyacetic acid (2,4-D) into Chinese hamster ovary (CHO) cells was studied. The cells mainly took up but did not metabolize the undissociated form of the herbicide. The uptake of 2,4-D was carried out against a concentration gradient and was inhibited by sodium azide and dinitrophenol.

Effects of 2,4-dichlorophenoxyacetic acid on polyamine transport and metabolism in Azospirillum brasilense Cd.

We had previously demonstrated that 1 mM 2,4-D inhibited cell growth, nucleic acid synthesis and protein synthesis (at the ribosomal level) of Azospirillum brasilense. These alterations were prevented by the presence of polyamines in the culture medium. On the other hand, polyamines did not affect the 2,4-D uptake.

The interaction of 2,4-dichlorophenoxyacetic acid, ribosomes and polyamines in Azospirillum brasilense.

2,4-Dichlorophenoxyacetic acid (2,4-D) is an herbicide used extensively in agriculture. We had previously determined that 1 mM 2,4-D could inhibit cell growth, DNA and protein synthesis of Azospirillum brasilense. The present work was designed to determine if these alterations are a consequence of 2,4-D action on polyamine biosynthesis and if the protein synthesis inhibition is a result of ribosomal impairment.

2,4-Dichlorophenoxyacetic acid action on in vitro protein synthesis and its relation to polyamines.

The effect of 2,4-dichlorophenoxyacetic acid (2,4-D) on the in vitro synthesis of proteins was studied in Chinese hamster ovary cells. A remarkable inhibition of the synthesis of proteins was observed when cells grew for 24 h in presence of 1 mM 2,4-D. This effect was reversed by adding 0.

In vitro protein synthesis is affected by the herbicide 2,4-dichlorophenoxyacetic acid in Azospirillum brasilense.

The effects of 2,4-dichlorophenoxyacetic acid (2,4-D) on growth and protein, DNA and RNA synthesis of Azospirillum brasilense Cd were studied. At a concentration of 1 mM, 2,4-D inhibited cell growth, an effect that was reversed either by transferring bacteria to a control (2,4-D-free) medium or to a 2,4-D-treated medium supplemented with polyamines. The herbicide also affected in vitro protein synthesis, either when Azospirillum brasilense Cd's own cellular mRNA or an artificial mRNA was used.

Effects of 2,4-dichlorophenoxyacetic acid on polyamine synthesis in Chinese hamster ovary cells.

It was found that 1 mM 2,4-dichlorophenoxyacetate (2,4-D) inhibited DNA and protein synthesis in Chinese hamster ovary (CHO) cells. When the possible relationship of this phenomenon to the presence of polyamines in the culture medium was investigated, it was found that: (a) the pesticide inhibited ornithine decarboxylase activity; (b) when the concentration of polyamines present in cells treated with the pesticide was determined, the putrescine concentration did not change, and the spermine and spermidine concentration decreased; (c) the addition of spermidine and spermine to CHO cells grown in the presence of 2,4-D normalized DNA and protein synthesis. Putrescine did not have any effect.

2,4-Dichlorophenoxyacetic acid effects on polyamine biosynthesis.

2,4-Dichlorophenoxyacetic acid (2,4-D) is a herbicide extensively used in agriculture. It was considered of interest to study its toxicity on animal cells. We had previously determined that 1 mM 2,4-D can inhibit cell growth, DNA and protein synthesis of cultured Chinese hamster ovary cells (CHO) with cell accumulation in the G1/S interphase of the cell cycle.

Changes in 2-aminoisobutyric acid and cycloleucine uptake produced by 2,4-dichlorophenoxyacetic acid in Chinese hamster ovary cells.

The effect of dichlorophenoxyacetic acid on the transport of two non-metabolizable amino acids, 2-aminoisobutyric acid (AIB) and cycloleucine (CL) was studied in chinese hamster ovary (CHO) cells. The herbicide did not exert any direct effect on the AIB transport. However, when the pesticide was in contact with the cells for 24 h an inhibition of the uptake was observed.

DNA and protein synthesis inhibition in Chinese hamster ovary cells by dichlorophenoxyacetic acid.

The effects of the herbicide dichlorophenoxyacetic acid (2,4-D) on DNA and protein synthesis were investigated in chinese hamster ovary cells (CHO) employing two different methods. The results showed that the herbicide affects DNA and protein synthesis depending on the stage of growth and method of treatment. 2,4-D action appears to concentrate the cells mainly in the G1/S boundary of the cell cycle.

Chloral hydrate inhibition in vitro of ATPase in membrane of rat erythrocytes and in microsomes of dog kidney external medulla.

The study of the general anesthetic chloral hydrate and its effects on rat erythrocyte membranes and dog kidney microsomes showed that ATPases were reversibly inhibited in every case. The inhibition was cooperative in the cases of (Mg2+ + Na+ + K+)-ATPase, Mg2+-ATPase and (Na+ + K+)-ATPase of rat erythrocyte membrane, while Ca2+-ATPase and (Mg2+ + Ca2+)-ATPase were non-cooperative. The chloral hydrate concentrations necessary to diminish the activity of the enzyme to half of the Vmax (I50) were 6 mM for Ca2+-ATPase from erythrocyte membranes and 82 mM for Mg2+-ATPase from intact external kidney medulla microsomes.

Ca2+-stimulated ATPase: inactivation by Ca2+ and mechanism.

The preincubation of the rat blood cell membranes in the presence of low Ca2+ levels causes an irreversible inhibition of the Ca2+-stimulated ATPase activity. The inactivation is dependent on the Ca2+ concentration and the apparent Ki is identical to the Ca2+ concentration needed to reach the half-maximal activity of the enzyme. This fact and the energy of activation (Ea = 13.

Kinetic studies and characteristics of a modifier of Ca2+-stimulated ATPase.

1. The thermostable modifier increases the Mg2+-stimulated ATPase with a parallel decrease of Ca2+-stimulated ATPase. 2.