Elani Laili, Juhari (2014) Metallothionein gene expression and genotoxic effects of heavy metals on Oreochromis sp. / Elani Laili Juhari. Masters thesis, University of Malaya.
Abstract
Metallothionein is a small, cysteine rich protein that aids in ion homeostasis in a cell. It binds naturally to zinc and also has the tendency to bind to other metals as well if present in the cell. This study was conducted in order to determine the effects of heavy metals exposure on metallothionein expression and other genotoxic effects on the tilapia fish as test subjects. Oreochromis sp. was chosen as the test subject because of the many advantages of its characteristics and it can be easily found in Malaysian rivers. Test subjects were exposed to two types of metals which were copper and lead. The concentrations of exposure were 0, 0.5, 1.0 and 1.5mg/L. Three approaches were selected to assess the effects of metal exposure which were gene expression analysis, micronucleus test and RAPD. For the gene expression analysis, lead at the highest concentration was able to induce the highest fold induction of metallothionein relative to the control sample at a 7.64-fold increase. Copper at 1.5mg/L and lead at 1.0mg/L were also able to significantly induce an increase in fold induction of 5.05 and 3.42-fold respectively. 1.5mg/L lead was able to induce the highest frequencies of micronucleus and nuclear abnormalities compared to the other samples. The banding patterns of RAPD bands were used to calculate the Jaccard distance of the exposed samples to the control sample. It was found that 1.5mg/L lead has the furthest Genetic Distance at 0.297. The sample that had the closest Genetic Distance to the control sample was copper at 0.5mg/L. The results of the micronucles test and RAPD were able to support the results of the gene expression study whereby lead created a bigger impact on the samples compared to copper at the same concentration.
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