The multi-xenobiotic resistance phenotype as a tool to biomonitor the environment

Organisms use a variety of cellular mechanisms to avoid the effects of toxins. These strategies include de-toxification of putative toxins, sequestration of the toxins or the utilization of transport mechanisms to actually prevent the entry and accumulation of toxins in the cells. These toxin avoidance mechanisms, which presumably evolved in response to natural toxins, can also be used to counter the effects of anthropogenic compounds introduced into the environment by the activities of our modern society. In this article we discuss (1) the use of transport mechanism strategies to protect against toxins and (2) the possible use of these mechanisms as biomarkers indicative of exposure to man-made toxins. We will first review the characteristics of these transport mechanisms, including their biology, genetics and molecular properties and then discuss their use as biomarkers.