Life evolved to take advantage of external environmental cues, especially those of a recurrent cyclical nature, in order to assimilate energy and nutrients for survival. Given the continuous light-dark cycles owing to the Earth’s rotation (circadian cycles), most life forms have adapted by synchronizing many of their physiological systems. These functions are governed and regulated at the biochemical, gene expression and post-transcriptional levels, which show wave-like behaviours. This review examines the role of biochemical oscillators in maintaining life processes and demonstrates how contaminants can influence these oscillations in the context of ecotoxicology. Circadian rhythms are one of the most important oscillatory mechanisms in organisms for optimal energy assimilation and metabolism. Circadian rhythms are synchronized with redox oscillators, such as peroxiredoxins (Prxs) and NADH/ATP, which regulate oxygen consumption (respiration), xenobiotic biotransformation and energy metabolism. Circadian rhythms are governed by clock genes (transcription factors) which in turn regulate many physiological functions that can determine the toxic outcomes of many contaminants. The toxicity of contaminants could be dramatically affected by the time of day of exposure to a given compound. Other oscillators show that cell activity could sustain oscillations at different frequency domains, and their potential to be disrupted by contaminants is explored. A case study is presented on the disruption of circadian rhythms in metallothioneins and peroxidases by cadmium exposure in freshwater mussels. Current evidence reveals that contaminants could disrupt the periodicity and intensity of rhythms in organisms. In conclusion, contaminants could influence the normal oscillatory pattern of biochemical functions and detoxification mechanisms in cells. Wave ecotoxicology or chronoecotoxicology consists in the study of the effects of xenobiotics on the cyclic or wave behaviour of biochemical systems of organisms and provides a more comprehensive view on the toxicity of xenobiotics.
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