Bioindicators are molecular tools used in ecology, physiology, environmental microbiology and other disciplines, to detect stressors and other environmental conditions surrounding an organisms or cells. What exactly is a bioindicator and how does it work?
Bioindicators, also known as biomarkers, are traditionally defined as organisms used to monitor the health of, or changes in, their surroundings or ecosystem. These can be plants, animals or bacteria that regularly produce certain molecular signals in response to changes in their environmental conditions. In biomedicine and biotechnology, a bioindicator can refer to the molecular signal itself, as a tool to evaluate the physiological state of an organism. For examples, when a vector is used to create a transgenic organism, it often carries a "marker gene" for a measurable compound that provides an indication of the success of gene transfer. Bioindicators are increasingly more common in biomedicine to detect physiological changes within an organism that are indicative of injury or disease. It is useful if the response is proportional to changes in environmental conditions (i.e. chemicals, heat, fatigue or injury), but they must always be reliably induced and indicative of the particular state of the cells or organism.
The use of bioindicators in different fields of biology, depends upon the development of methods to detect/ sense the biochemical change that is induced whenever the stressor is present.
Natural bioindicators exist in the form of indigenous physiological responses to environmental conditions that have been documented to reliably exist whenever the stressor is present. GMOs can be constructed using gene cloning techniques, that express a specific bioindicator, as a programmed response to a particular stressor. Construction of such a bioindicator might involve linking the gene for a biomarker such as an antibody, fluorescent dye or enzyme, such as firefly luciferase, to a promoter that is turned on when the stressor is present.
The presence of bioindicators in biological media or samples is then detected using biosensors. An example of a biosensor is the tool developed by Axela Biosensors (Toronto, ON) that detects two proteins released by injured infant brains. In this case, the proteins are natural bioindicators of damaged brain tissue.