Exposure of Enchytraeus albidus to Cd and Zn - changes in cellular energy allocation (CEA) and linkage to transcriptional, enzymatic and reproductive effects.

Cellular energy allocation (CEA) is a measure of the energy status of an organism. The effects of Cd and Zn (reproduction EC(50)s and EC(90)s) on the total energy budget of Enchytraeus albidus (Oligochaeta) were assessed through CEA determination, over periods of time from 0 to 8 d. Results showed reduction on the energy reserves for both metals after 2 d exposure. Lipids were the first reserves to be used and carbohydrates were reduced exclusively after Cd exposure. Electron transport system (ETS) activities were enhanced, suggesting increased metabolism and higher energy requirements for metal detoxification. This was supported by previous results at transcription level, where an up-regulation of genes involved in the mitochondrial oxidative phosphorylation was verified. Additionally, the reduction of CEA may be related with the decrease on the reproductive output. These results showed the relevance of integrating various endpoints, which enabled an overview of various processes and to unravel mechanisms of action of chemicals.