RESPUESTAS BIOQUÍMICAS EN LA LOMBRIZ DE TIERRA Eisenia andrei EXPUESTA A CADMIO | BIOCHEMICAL RESPONSES IN THE EARTHWORM Eisenia andrei EXPOSED TO CADMIUM

The cadmium (Cd) bioaccumulation on metallothioneins (MT), total proteins (TP), sulfhydryl groups (-SH) and tiobarbituric acid reaction substances (TBARS) levels were determined in medium-anterior (MA) and medium-posterior (MP) corporal regions of the earthworm Eisenia andrei. The organisms were exposed to concentrations of 0; 2.50 and 10.30 mg Cd/kg of substrate, during 7, 15 and 21 days. Cd levels increased in the exposed organisms proportionally to the concentrations and duration of exposure; this metal was mostly accumulated to the MP region. Cd-treatment caused increases in the MT, -SH and TP levels in both corporal regions, with the highest values in MA. TBARS concentrations increased in doses-days relationship, showed the highest levels in MA; this increment is probably associated to the Cd-bioacumulation that can affect the mechanisms of defenses against reactive oxygen species. MT concentrations in exposed organisms suggest their relevance as effective response of molecular defense against Cd toxicity. These corporal biochemical responses associated to Cd-uptake form part of the molecular defense system that avoids interferences on the reproductive tissue (clitellum), allowing to accumulate the highest quantity of Cd in the MP region. Eisenia andrei has a differential capacity along its body to modulate adjustments of molecular responses, which could allow the tolerance and effectiveness of survival in Cd-polluted soils