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The long-term (postponed) consequences of the separate and combined effects of Cu2+ ions (0.001, 0.01, and 0.1 mg/L) and a low-frequency electromagnetic field (50 Hz, 10 μT) on roach Rutilus rutilus (L.) embryos have been studied, bringing to light the exposure to these factors to changes in the size and weight parameters, the activity of glycosidases (sucrase, maltase, and amylolytic activity), and the kinetic characteristics of maltose hydrolysis in the intestines of underyearlings exposed at a stage of embryos. Increased body weight, body length, and intestine length are revealed in fish exposed to the electromagnetic field and the combined treatment of an electromagnetic field and Cu2+ ions. Compared with the control, the activities of sucrase and maltase are higher, while the amylolytic activity is lower in roach exposed to different combinations of the factors. The electromagnetic field compensates the inhibitory influence of Cu2+ on amylolytic and maltase activity. The values ​​of the Michaelis constant (Km) of maltose hydrolysis in the intestines of underyearlings exposed to these impacts exceed those in the control. This result indicates a decrease in the enzyme affinity for the substrate, probably caused by the separate and combined influence of Cu2+ and the electromagnetic field on the roach during early development. These results are important for assessing environmental risks in industrial areas. [ABSTRACT FROM AUTHOR]

The activity of glycosidases (maltase activity and amylolytic activity) in the intestinal mucosa of juvenile common carp Cyprinus carpio (L.) under a sharp increase in water temperature depends on its physiological state (satiety or starvation). The fish are acclimated to a temperature of 22°С during the summer (young-of-the-year) and winter (yearling) seasons. An increase in water temperature at a rate of 8.0°C/h leads to an increase in amylolytic activity in well-nourished fish, but the maltase activity does not change. Starving for 3 or 10 days changes the response of glycosidase to temperature stress: the maltase activity increases, but amylolytic activity does not change. Short-term starvation does not affect the thermal tolerance of juvenile common carp; i.e., the values of the critical thermal maximum in hungry and well-nourished specimens do not differ. [ABSTRACT FROM AUTHOR]

The effects of 30-day exposure to Roundup at concentration of 2 μg/L and of thermal stress on the intestinal glycosidase activities (maltase and amylolytic activities (AA)), brain acetylcholinesterase (AChE) activity and water-soluble protein (WSP) content in juvenile specimens of Amur sleeper Perccottus glenii Dybowski have been studied. Additionally, critical thermal maximum (CTM) and final selected temperature (FST) are determined in fish of control (exposure to 0 μg/L Roundup) and Roundup-exposed groups. After Roundup exposure AA and WSP content were 27 and 31% lower respectively, maltase and AChE activities did not change. An increase in water temperature at a rate of 8°C/h decreased AA by 60%, maltase activity by 18% and WSP content by 28% in fish of the control group; but decreased AA by 76%, AChE activity by 29%, WSP content by 40%, and increased maltase activity by 11% in fish of the Roundup-exposed group. The recovery treatment during 12 days in a thermal gradient with herbicide-free water (temperature range between 14 and 31°C) reduced the inhibitory effect of heating on AA, but increased it the on AChE and WSP content in fish from both control and Roundup-exposed groups (on maltase activity only in the fish of exposed group). No significant differences were noticed in CTM and FST values in fish of control and Roundup-exposed groups. [ABSTRACT FROM AUTHOR]