Enzymatic and Biochemical Processes

Not only are enzyme activities inhibited, but they can also be induced by a toxicant agent. Quantitative measures exist for a broad variety of these enzymes. Mixed-function oxidases are perhaps the best studied, with approximately 100 now identified from a variety of organisms. Activity can be measured or the synthesis of new mixed-function oxidases may be identified using antibody techniques. DNA repair enzymes can also be measured and their induction is an indication of DNA damage and associated genotoxic effects. 

The stress-related proteins discussed above are induced by a variety of stressors. However, other groups of proteins are induced by specific materials. Metallothioneins are proteins that are crucial in reducing the effects of many heavy metals. Originally evolved as important players in metal regulation, these proteins sequester heavy metals and thereby reduce their toxic effects. Metallothioneins are induced and like many proteins can be identified using current immunological techniques. 

Birds and mammals have additional immunological mechanisms and can produce antibodies. Rates of antibody production, the existence of antibodies against specific challenges, and other measures of antibody-mediated immunological responses should prove useful in these organisms. 

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