Mechanisms of Detoxification and Transport

The detoxification and excretion of xenobiotics (i.e., foreign compounds, including diet-derived allelochemicals) involve a suite of highly complex processes that allow an organism to respond to its internal and external chemical environments. Suchmetabolic resistance involves the biochemical transformation 

In order for allelochemicals to enter the body of a herbivore, absorption must occur across the gut lining. Curtailing the initial absorption of dietary allelochemicals may be a herbivore s first line of defense against plant toxins. Studies have citied the lack of absorption or metabolism of lipophilic plant secondary metabolites (i.e., terpenes), conducive to phase I or II detoxification, in the gut of terrestrial herbivores rather these compounds are excreted unchanged in the feces (Marsh et al. 2006b). While physical barriers or surfactants have been used to explain this limited adsorption in both marine and terrestrial herbivores (Lehane 1997 Barbehenn and Martin 1998 Barbehenn 2001 for review of marine herbivores, see Targett and Arnold 2001), active efflux of plant allelochemicals out of enterocytes into the gut lumen has received limited attention until now. 

A relatively small number of investigators have focused on the role of detoxification and transport enzymes in the feeding ecology of marine consumers. Here, we outline three examples of this small, but growing body of work. The first example 

Modified from Goldstone et al. (2006). Hayes et al. (2005) and Dean and Annilo 

CYP cytochrome P450 GST glutathione S-transferasc ABC ATP Binding Cassette 

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