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(T/EH053) Toxic effect of cadmium on growth and presence of class III metallothioneins as mechanism of tolerance in Tetraselmis suecica (Kylin) Butch cells. Torres, Enrique1, Pérez-Rama, Mónica1, Abalde, Julio1, Orosa, Miguel1, 1 ABSTRACT- In the last years metals has become one of the most important environmental problems. Metals stay largely in the aquatic environments, because, in contrast to herbicides, pesticides, and other potential pollutants, they cannot undergo breakdown and they persist in sediments from where they are slowly released into the water and become available to the organisms. Microalgae are one of the most important organisms of our ecosystems being seriously affected by metal pollution. Cadmium is recognized as one of the most toxic metals with no described biological function, that produces serious hazards to aquatic organisms. The biological effects of cadmium on aquatic organisms have been studied extensively, especially in microalgal cells, because they play a crucial role in most environments. Effect of cadmium on growth of marine microalgae Tetraselmis suecica (Kylin) Butch was studied. Its EC50 value was 5.8 mg l-1 of cadmium after 96 hours of exposure to this metal. Microalgae, as other organisms, have developed different mechanisms to protect themselves from metal poisoning. Class III metallothioneins were investigated for their involvement in a possible tolerance mechanism present in this microalga when exposed to cadmium. A set of these molecules was purified from these microalgal cells after exposition to the metal. These polypeptides were analyzed by capillary zone electrophoresis, a technique allowing the length of the metallothioneins synthesized by this microalga to be known. T. suecica cells were able to synthesize class III metallothioneins of three to six subunits of ( Key words: cadmium, microalga, toxicity, metallothioneins |
-Glu-Cys). The most abundant polypeptide possessed four subunits and (