Detoxification and sensing mechanisms are of similar importance for Cd resistance in .

The present study employed mass spectrometry (ICP-MS) to measure the internal cadmium concentrations (Cd) in to determine Cd uptake from a Cd-containing environment as well as Cd release under Cd-free conditions. To analyze the functional role of several ATP binding cassette (ABC) transporters (e.g., HMT-1 and MRP-1) and phytochelatin synthase (PCS), we compared wild-type (WT) and different mutant strains of . As a pre-test on selected mutant strains, several time-resolved experiments were performed to determine the survival rate and avoidance behavior of under Cd stress, which confirmed the already known Cd sensitivity of the deletion mutants Δ, Δ, and Δ. In addition, these experiments revealed flight reactions under Cd stress to be almost completely absent in Δ mutants. The ICP-MS studies showed Cd uptake to be significantly higher in Δ and WT than in Δ. As Cd is ingested with food, food refusal due to very early Cd stress and its perception was likely the reason for the reduced Cd uptake of Δ. Cd release (detoxification) was found to be maximal in Δ, minimal in Δ, and intermediate in WT. High mortality under Cd stress, food refusal, and minimal Cd release in the case of Δ suggest a vital importance of the HMT-1/PCS-1 detoxification system for the survival of under Cd stress. High mortality under Cd stress, absence of an avoidance behavior, missing food refusal, and maximal Cd release in the case of Δ indicate that MRP-1 is less important for Cd detoxification under severe stress, but is probably important for Cd perception. Accordingly, our results suggest that the survival of WT under Cd stress (or possibly other forms of metal stress) primarily depends on the function of the HMT-1/PCS-1 detoxification system and the presence of a sensing mechanism to control the uptake of Cd (or other metals), which keeps internal Cd (or metal) concentrations under control, to some extent, for the timely mobilization of protection and repair systems.