Evaluation of metallothionein response in Lymnaea stagnalis pond snail to exposured to trace metals and thiocarbamate fungicide

Abstract

Pulmonate mollusks posses high uptake rates of dissolved metals and their bonding, mainly Cd, Zn and Cu by the metal-buffering protein, metallothionein (MT). However, most investigations are focused at the terrestrial species, whereas aquatic snails are studied scantly. Therefore, the main goal of our study was to evaluate a specificity of metal-binding function of the metallothionein in Lymnaea stagnalis pond snail. The mollusks were subjected to typical metallothionein inducers Cd2+, 15 g•L-1; Cu2+, 10 g•L-1; Zn2+, 130 g•L-1 and oxidative stress inducer thiocarbamate Tattoo fungicide, 91 g L−1 during 14 days. Applied concentrations corresponded to the ecologically rele­vant concentrations. Metal concentrations and metallothionein characteristics in a digestive gland were analyzed. In present study, all exposures to metals caused the elevation of the concentration of metals (Zn, Cu or Cd) in tissues and the total level of metallothionein detected from their thiols (MT-SH). Particularly, Zn level in tissues was increased by ~2−3 times in all cases of the exposure to metals. Cd increased the level of metal-contained form of the metallothionein (MT-Me). Tattoo affected the levels of metals and MT-SH in the tissue to low extent but caused the redistribution of metals between the metallothionein (increase) and other compounds. The distortion of the elution profile of metallothionein on the DEAE-cellulose was shown at each exposure. To summarize, snails demonstrated a wide spectrum of responses and juxtaposition of different characteristics depending on the exposure. The responses to metals and Tattoo were distinguished by the detection of metallothionein concentration. The primary reasons for the effect of thiocarbamate on the metal homeostasis needs further investigations.

Keywords

• pulmonate mollusk
• trace metals
• thiocarbamate fungicide