Detoxification and sensing mechanisms are of similar importance for Cd resistance inCaenorhabditis elegans.
The present study employed mass spectrometry (ICP-MS) to measure the internal cadmium concentrations (Cdint) inCaenorhabditis elegansto 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 ofC. elegans. As a pre-test on selected mutant strains, several time-resolved experiments were performed to determine the survival rate and avoidance behavior ofC. elegansunder Cd stress, which confirmed the already known Cd sensitivity of the deletion mutantsmrp-1Δ,pcs-1Δ, andhmt-1Δ. In addition, these experiments revealed flight reactions under Cd stress to be almost completely absent inmrp-1Δ mutants. The ICP-MS studies showed Cd uptake to be significantly higher inmrp-1Δ and WT than inhmt-1Δ. 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 ofhmt-1Δ. Cd release (detoxification) was found to be maximal inmrp-1Δ, minimal inhmt-1Δ, and intermediate in WT. High mortality under Cd stress, food refusal, and minimal Cd release in the case ofhmt-1Δ suggest a vital importance of the HMT-1/PCS-1 detoxification system for the survival ofC. elegansunder Cd stress. High mortality under Cd stress, absence of an avoidance behavior, missing food refusal, and maximal Cd release in the case ofmrp-1Δ 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.
Institute of Zoophysiology, University of Münster (WWU), Münster 48143, Germany.
Sarah A
SA
Winter
Institute of Zoophysiology, University of Münster (WWU), Münster 48143, Germany.
Ramona
R
Dölling
Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Schmallenberg 57392, Germany.
Burkhard
B
Knopf
Institute of Zoophysiology, University of Münster (WWU), Münster 48143, Germany.
Martha N
MN
Mendelski
Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Schmallenberg 57392, Germany.
Christoph
C
Schäfers
Institute of Zoophysiology, University of Münster (WWU), Münster 48143, Germany.
Rüdiger J
RJ
Paul
Applied sciences; Food science