RESEARCH ARTICLE SUMMARY
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This review presents evidence that ultra-low doses of biologically active agents—at concentrations approaching or even below one molecule per cell—can trigger measurable and reproducible biological effects across a wide range of organisms, from unicellular life to humans.
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The authors describe how biological systems possess highly sensitive receptor and signaling mechanisms capable of amplifying extremely small signals, allowing one or very few molecules to activate thousands of neighboring cells through cascade and bystander-broadcast effects.
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Across multiple biological models, these ultra-low dose effects consistently follow hormetic, biphasic dose-response patterns, with low doses stimulating protective or adaptive responses and higher doses producing inhibition or toxicity.
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Examples reviewed include immune activation (macrophage phagocytosis), unicellular signaling, pheromone communication, GPCR activation, and neuroprotective mechanisms, demonstrating that ultra-low dose sensitivity is widespread and evolutionarily conserved.
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The authors conclude that ultra-low dose biology challenges conventional assumptions about dose thresholds and has important implications for toxicology, radiobiology, systems biology, evolutionary theory, and potential clinical applications, warranting greater scientific attention and paradigm reassessment.
SOURCE ARTICLE:
https://doi.org/10.1016/j.phrs.2021.105738