exposure
Definition
In chain of causality frameworks, exposure refers to the initial factor, condition, or intervention that potentially triggers a cascade of biological events leading to an outcome. Exposures can be environmental (toxins, diet, pathogens), genetic (mutations, polymorphisms), pharmacological (drugs, therapies), or behavioral (smoking, exercise). Understanding exposure is critical for establishing causal relationships in biological systems, as it represents the starting point in mechanistic pathways. In network biology, exposures serve as perturbation nodes that initiate signal propagation through molecular networks, affecting downstream genes, proteins, and phenotypes. Proper characterization of exposures enables researchers to map causal chains, identify mediators, and distinguish direct effects from indirect consequences.
Visualize exposure in Nodes Bio
Researchers can visualize exposure effects by mapping how initial perturbations propagate through biological networks. Create network graphs showing exposure nodes connected to immediate molecular targets, intermediate mediators, and ultimate phenotypic outcomes. Layer temporal data to reveal sequential activation patterns, and use pathway enrichment to identify which biological processes are affected by specific exposures, enabling causal inference and mechanism discovery.
Visualization Ideas:
- Exposure-to-outcome causal networks showing direct and indirect pathways
- Time-series networks displaying temporal propagation of exposure effects through molecular layers
- Multi-exposure comparison networks identifying shared and unique downstream targets
Example Use Case
A toxicology team investigating bisphenol A (BPA) exposure maps how this endocrine disruptor affects cellular networks. They model BPA as the exposure node, connecting it to estrogen receptors (immediate targets), then to downstream gene expression changes in hormone-responsive pathways, followed by altered cell proliferation markers. The network reveals both direct receptor binding and indirect effects through epigenetic modifications, helping distinguish primary mechanisms from secondary consequences and identifying potential biomarkers for exposure assessment.