重金屬鋅或鎘誘發海葵(Aiptasia pulchella)體內金屬硫蛋白之研究

Abstract

Metallothioneins (MTs) are cysteine rich, heat stable and low molecular weight proteins. They have been widely used as biomarkers to reflect the level of heavy metal pollution. Sea anemones (Aiptasia pulchella) should reflect the real condition of its surroundings due to its sedentary. Normally, they are asexually reproduced by pedal laceration in laboratory cultural system. After exposure to different concentrations of cadmium (0, 0.05, 0.25 or 0.5 mg/L for 24, 48 or 72 hours) or zinc (0, 0.25, 0.5 or 1.0 mg/L for 24, 48 or 96 hours), obvious morphological alterations in A. pulchella were recorded. Their tentacles turned dark and their body shrank. By using atomic absorption to measure Zn or Cd concentration in A. pulchella, those metal-exposed sea anemones showed a time-dependent and a dose-dependent both zinc and cadmium accumulation. From the results of immunoblotting, the amount of metallothioneins in those metal-exposed A. pulchella increased following by a time-and dose-course. The molecular weight of the detected MTs was between 11 and 17 kDa. There were at least three bands appeared. One is assumed to be constitutive MT and the others are assumed to be induced metallothioneins. Immunofluorecent antibody detection of the distribution of metallothionein in A. pulchella under zinc or cadmium treatment demonstrated that the fluorescent particles in the body column significantly increased and the fluorescence of tentacles also intensified. The induction of metallothioneins in A. pulchella was shown being responsive to different concentrations of metals.