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

Abstract

The present study employed mass spectrometry (ICP-MS) to measure the internal cadmium concentrations (Cdint) in Caenorhabditis elegans 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 C. elegans. As a pre-test on selected mutant strains, several time-resolved experiments were performed to determine the survival rate and avoidance behavior of C. elegans under Cd stress, which confirmed the already known Cd sensitivity of the deletion mutants mrp-1Δ, pcs-1Δ, and hmt-1Δ. In addition, these experiments revealed flight reactions under Cd stress to be almost completely absent in mrp-1Δ mutants. The ICP-MS studies showed Cd uptake to be significantly higher in mrp-1Δ and WT than in hmt-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 of hmt-1Δ. Cd release (detoxification) was found to be maximal in mrp-1Δ, minimal in hmt-1Δ, and intermediate in WT. High mortality under Cd stress, food refusal, and minimal Cd release in the case of hmt-1Δ suggest a vital importance of the HMT-1/PCS-1 detoxification system for the survival of C. elegans under Cd stress. High mortality under Cd stress, absence of an avoidance behavior, missing food refusal, and maximal Cd release in the case of mrp-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.

PMK-1 p38 MAPK promotes cadmium stress resistance, the expression of SKN-1/Nrf and DAF-16 target genes, and protein biosynthesis in Caenorhabditis elegans

“…6 b). This mechanism might explain the elevated Cd resistance of daf - 16 Δ, as a Cd-induced increase in mrp - 1 expression could have improved the Cd resistance of daf - 16 Δ (cf., Winter et al 2016 ). The result of reduced mrp - 2 mRNA and MRP-2::DsRed fusion protein levels in daf - 2 Δ or daf - 2 RNAi-treated worms in comparison to control worms (R. J. Paul, unpublished data) shows that mrp - 2 expression is also negatively controlled by DAF-16.…”

Aerosol dilution for the introduction of complex matrix samples in plasma-based spectrometry techniques: a tutorial review

“…Iron, Ni, Cu, Zn, and Au were also analyzed in addition to Pd and Pt. The CRC technology was used to minimize the 65 Cu 40 Ar + interference on 105 Pd + determination, using He at 5.0 mL min À1 .…”

“…In this way, AD has been used by some authors as a sample introduction procedure to reduce matrix interferences in drug analysis by ICP-MS (Table 3). [25][26][27][64][65][66][67] Pinheiro et al published two papers focused on drug analysis 27,66 and one for dietary supplement, 26 using AD ICP-MS, setting nebulization and dilution gas ow rates at 0.62 L min À1 and 0.40 L min À1 , respectively. Microwave-assisted acid decomposition was employed in these three papers.…”

“…In this way, AD has been used by some authors as a sample introduction procedure to reduce matrix interferences in drug analysis by ICP-MS (Table 3). 25–27,64–67…”

“…Winter et al estimated the Cd intake and release by different strains of the worm Caenorhabditis elegans , by using AD in ICP-MS, with nebulizer and dilution gas flow rates of 0.92 L min −1 and 0.16 L min −1 , respectively. 65 Vižintin and collaborators studied electroporation on cell survival and membrane permeabilization, and they determined Al, Pt, Cr, Mn, Fe, and Ni in the electrode material release using ICP-MS or ICP-MS/MS equipped with AD, which conditions varied between 0.85–0.95 L min −1 for the nebulizer gas flow rate and 0.10–0.20 L min −1 for the dilution gas flow rate. 68 Zhang et al proposed a new sample preparation method for dry ashing of botanical samples, resulting in solutions containing 4% (v/v) of HNO 3 , which were analyzed for the determination of 28 elements using the AD system.…”