Search

The isoflavones genistein and daidzein are flavonoid compounds mainly found in legumes, especially in soybeans and their derived products. These flavonoids can be present in agricultural, domestic and industrial wastewater effluents as a result of anthropogenic activities and may be discharged in the environment. Due to the large growth of the aquaculture sector in recent decades, new and cost-effective fish feeds are being sought, but there is also a particular need to determine the effects of exposed flavonoids on fish in the aquatic environment, as this is the main route of exposure of organisms to endocrine disruptors. This study evaluated the possible effects of these isoflavones on juveniles of Solea senegalensis and Solea solea. After 48–96 h of exposure, the acetylcholinesterase activity in the sole head tissues was measured, and the cholinesterase activity in juveniles of common sole (S. solea) was determined. Experiments were carried out to determine the optimal pH, investigate the specificity of three substrates (acetylthiocholine, butyrylthiocholine, propionylthiocholine) on cholinesterase activity and determine the kinetic parameters (Vmax and Km). The results obtained showed that neither genistein nor daidzein exposure to S. senegalensis and S. solea inhibited the activity of acetylcholinesterase at the tested concentrations (genistein: 1.25, 2.5, 5, 10 and 20 mg/L; daidzein: 0.625, 1.25, 2.5, 5 and 10 mg/L).

The characterization of cholinesterase activity in brain and muscle of gilthead seabream was carried out using four specific substrates and three selective inhibitors. In addition, K m and V max were calculated from the Michaelis–Menten equation for ASCh and BSCh substrates. Finally, the in vitro sensitivity of brain and muscle cholinesterases to three organophosphates (OPs) was also investigated by estimating inhibition kinetics. The results indicate that AChE is the enzyme present in the brain, whereas in muscle, a typical AChE form is present along with an atypical form of BChE. Very low ChE activity was found in plasma with all substrates used. The inhibitory potency of the studied OPs on brain and muscle AChEs based on bimolecular inhibition constants (k i ) was: omethoate < dichlorvos < azinphosmethyl-oxon. Furthermore, muscle BChE was found to be several orders of magnitude (from 2 to 4) more sensitive than brain and muscle AChE inhibition by dichlorvos and omethoate.

Se realiza una revisión de biomarcadores de estrés o específicos de diferentes contaminantes orgánicos (plaguicidas, hidrocarburos aromáticos policíclicos, dioxinas) e inorgánicos (metales) en diferentes especies de peces (larvas y adultos) de hábitos sedentarios y bentónicos, a nivel bioquímico, celular y molecular. Los resultados que se discuten proceden de experimentos en distintas condiciones experimentales (agua- sedimento-vía trófica). La toxicidad de los contaminantes (mortalidad, histopatología) es progresiva con la concentración del tóxico, siendo las larvas de peces en diferentes fases de su desarrollo (fase endo-exotrófica) más resistente a los contaminantes, en general, que los ejemplares adultos. Los órganos diana frente a contaminantes orgánicos e inorgánicos son preferentemente las branquias y el hígado (vía aguasedimento) y el tracto digestivo cuando la exposición es vía trófica, siendo el sistema nervioso el órgano diana para plaguicidas organofosforados. Existe una correlación significativa (positiva o negativa) entre la inducción de EROD y CYP1A en peces expuestos a benzo(a)pireno y dioxinas. Las respuestas tóxicas de los metales permiten corroborar sus efectos a nivel fisiológico y patológico subcelular: osmoregulación (células de cloruro); respiración (células pilares), y mecanismos protectores (células mucosas). La peroxidación lipídica es evidenciada en ejemplares expuestos tanto a contaminantes inorgánicos y orgánicos.

This study was conducted to examine the acute toxicity of the organophosphorus pesticide (OP) parathion on embryos and yolk-sac larvae of gilthead seabream (Sparus aurata), and to investigate the effects of this compound on cholinesterase and carboxylesterase activity of seabream larvae in the phase of endogenous feeding. The 72-h LC50 for yolk-sac larvae (0.523 mg L-1) was about two-fold lower than the 48-h LC50 for embryos (1.005 mg L-1). Parathion significantly inhibited the activity of ChE and CaE activity in yolk sac larvae but there were not significant differences in the sensitivity of both esterases to parathion as inferred by their 72-h IC50 values. Larvae exposed to parathion for 72 h showed a 70% inhibition of the whole body acetylcholinesterase at approximately the LC50. © 2009 Wiley Periodicals, Inc.