Acute Toxicity of Nitrite to Rainbow Trout (Salmo gairdneri): Effects of pH, Nitrite Species, and Anion Species

1981 ◽  
Vol 38 (4) ◽  
pp. 387-393 ◽  
Author(s):  
Rosemarie C. Russo ◽  
Robert V. Thurston ◽  
Kenneth Emerson
Keyword(s):  
Rainbow Trout ◽  
Ph Dependence ◽  
Salmo Gairdneri ◽  
Aquatic Life ◽  
Nitrite Toxicity ◽  
Effects Of Ph ◽  
Chloride Sulfate ◽  
Ph Dependent ◽  
Nitrate Anions ◽  
Anion Species

The toxicity of nitrite to rainbow trout is pH-dependent within the range considered acceptable to most freshwater aquatic life (pH 6.5–9.0). Both of the nitrite species, NO2− and HNO2, are toxic. It is recommended that nitrite criteria to protect freshwater aquatic life be based on total nitrite, and that such criteria reflect the pH dependence of nitrite toxicity. Variation in the toxicity of nitrite in the presence of chloride, sulfate, phosphate, and nitrate anions has also been demonstrated. It is concluded that the toxicity of nitrite to fishes, in addition to being pH-dependent, is also dependent in varying degrees upon many of the anions that are commonly found in natural aquatic environments.Key words: nitrite, pH, chloride, phosphate, sulfate, toxicity, rainbow trout, Salmo gairdneri

The Influence of pH, Water Hardness, and Alkalinity on the Acute Lethality of Zinc to Rainbow Trout (Salmo gairdneri)

1985 ◽  
Vol 42 (4) ◽  
pp. 731-736 ◽  
Author(s):  
R. W. Bradley ◽  
J. B. Sprague
Keyword(s):  
Rainbow Trout ◽  
Water Hardness ◽  
Salmo Gairdneri ◽  
Total Hardness ◽  
Zinc Toxicity ◽  
Carbonate Alkalinity ◽  
Effects Of Ph ◽  
Order Of Magnitude ◽  
Low Toxicity ◽  
Influence Of Ph

The acute lethality of dissolved zinc to rainbow trout (Salmo gairdneri) was significantly increased at higher pH and lower hardness levels. Changes in pH from 5.5 to 7.0 increased zinc toxicity by factors of 2 to 5, depending on total hardness levels. A decrease in hardness from 386 to 31 mg CaCO3/L increased zinc toxicity by more than an order of magnitude at both pH levels. These effects of pH and hardness were not caused by changes in the chemical speciation of zinc. An increase in carbonate alkalinity from 8.4 to 24 mg CaCO3/L at pH 7.0 did not significantly alter zinc toxicity at either hardness level. Thus, carbonate alkalinity is not an important factor at or below pH 7.0. At low hardness, dissolved zinc was more than 10 times as toxic at pH 9.0 as at pH 5.5. Two competing mechanisms appear to operate: as the pH rises, dissolved zinc becomes increasingly toxic, but at higher pH levels it is increasingly replaced by zinc precipitate, which is of very low toxicity to fish.

Influence of Water Hardness, pH, and Alkalinity on the Mechanisms of Copper Toxicity in Juvenile Rainbow Trout, Salmo gairdneri

1986 ◽  
Vol 43 (8) ◽  
pp. 1488-1496 ◽  
Author(s):  
Darrel Jon Laurén ◽  
D. G. McDonald
Keyword(s):  
Rainbow Trout ◽  
Pure Copper ◽  
Copper Toxicity ◽  
Water Hardness ◽  
Salmo Gairdneri ◽  
Sodium Efflux ◽  
Juvenile Rainbow Trout ◽  
Influence Of Water ◽  
Effects Of Ph ◽  
High Alkalinity

Juvenile rainbow trout were exposed to 25–400 μg copper∙L−1 for 24 h. Water hardness, pH, and alkalinity were varied independently at a constant [Na+]. Net and unidirectional sodium fluxes were measured in hard and soft, low-alkalinity water and in hard, high-alkalinity water at neutral pH and pH 5.0. In low alkalinity water, Na+ uptake (Jin) was inhibited at copper concentrations as low as 25 μg∙L−1, and sodium efflux (Jout) was stimulated above 100 μg∙L−1. High-alkalinity water significantly reduced the effects of copper on Jin and Jout, but there was no significant effect of increasing water hardness. The effects of pH 5.0 and copper were additive from 25 to 100 μg∙L−1, but a pure copper effect was found from 200 to 400 μg∙L−1. Fish died when they had lost about 50–55% of their exchangeable Na+ pool. Water hardness and alkalinity had no effect on the apparent uptake of copper, but copper uptake was reduced by about 50% at pH 5.0.

Rationalizing the pH-Activity Response for Escherichia Coli’s Glycinamide Ribonucleotidetransformylase Through Computational Methods

2019 ◽  
Author(s):  
Adrian Roitberg ◽  
Pancham Lal Gupta
Keyword(s):  
Transfer Reaction ◽  
Catalytic Mechanism ◽  
Ph Dependence ◽  
Ph Effects ◽  
Dependent Manner ◽  
E Coli ◽  
Gar Tfase ◽  
Activity Curve ◽  
Ph Dependent ◽  
Formyl Transfer

<div>Human Glycinamide ribonucleotide transformylase (GAR Tfase), a regulatory enzyme in the de novo purine biosynthesis pathway, has been established as an anti-cancer target. GAR Tfase catalyzes the formyl transfer reaction from the folate cofactor to the GAR ligand. In the present work, we study E. coli GAR Tfase, which has high sequence similarity with the human GAR Tfase with most functional residues conserved. E. coli GAR Tfase exhibits structural changes and the binding of ligands that varies with pH which leads to change the rate of the formyl transfer reaction in a pH-dependent manner. Thus, the inclusion of pH becomes essential for the study of its catalytic mechanism. Experimentally, the pH-dependence of the kinetic parameter kcat is measured to evaluate the pH-range of enzymatic activity. However, insufficient information about residues governing the pH-effects on the catalytic activity leads to ambiguous assignments of the general acid and base catalysts and consequently its catalytic mechanism. In the present work, we use pH-replica exchange molecular dynamics (pH-REMD) simulations to study the effects of pH on E. coli GAR Tfase enzyme. We identify the titratable residues governing the pH-dependent conformational changes in the system. Furthermore, we filter out the protonation states which are essential in maintaining the structural integrity, keeping the ligands bound and assisting the catalysis. We reproduce the experimental pH-activity curve by computing the population of key protonation states. Moreover, we provide a detailed description of residues governing the acidic and basic limbs of the pH-activity curve.</div>

Temperature Selection of Rainbow Trout (Salmo gairdneri) Fingerlings in Vertical and Horizontal Gradients

1971 ◽  
Vol 28 (11) ◽  
pp. 1801-1804 ◽  
Author(s):  
R. W. McCauley ◽  
W. L. Pond
Keyword(s):  
Rainbow Trout ◽  
Salmo Gairdneri ◽  
Temperature Preference ◽  
Temperature Selection ◽  
Horizontal Gradients ◽  
Significant Difference ◽  
Preferred Temperatures ◽  
Laboratory Investigations ◽  
Horizontal Temperature Gradients ◽  
Selection Of

Preferred temperatures of underyearling rainbow trout (Salmo gairdneri) were determined in both vertical and horizontal temperature gradients. No statistically significant difference was found between the preferred temperatures by the two different methods. This suggests that the nature of the gradient plays a lesser role than generally believed in laboratory investigations of temperature preference.

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