The Effects Of Copper On Physiological Toxicity And The Expressions Of Immune-Related Genes In Gift Tilapia

Tilapia is one of the most popular aquaculture fish in the world. It is widely farmed in many countries. The Food and Agriculture Organization of the United Nations recommends tilapia to the world for its wide farming.This study determined the accumulation of copper in tissues after exposure by ICP-MS mass spectrometry analysis method. Enzyme linked immunsorbent assay(ELISA) was used to determine the antioxidant enzyme activity. Realtime fluorescence quantitative PCR was used to determine the expressions of immune related genes There are some studies on dietary the effects of copper on the physiology of fish. This study focused on the effects of dissolved copper in GIFT Tilapia. This is similar to what occurs in the copper polluted ecosystem by industrial wastewater and agricultural activity. Study on the tissue distribution of copper help better understand the healthy of cultured tilapia in the polluted environment. Meanwhile, Study on the alterations of the expressions of immue-related genes by copper provided evidence for the effects of copper on the immune system in tilapia.. The main results are as follows:1.Accumulation of copper in the tissues of GIFT TilapiaCuSO4 is widely used in aquaculture. The concentration can reach up to 1mg/L when it is used to prevent and treat parasitic diseases in fish. The experiment had five copper concentrations content of 0(control), 1 2, 4 and 6 mg/L.. Fish were exposed to these concentrations for forty days. The growth of different groups have no significant difference. After the exposure, the gill, liver, kidney, muscle and intestine were obtained and copper levels in the tissues were measured.. The levels of copper in the tissues(from high to low) ranked liver > intestine > kidney > gill and muscle. There was very limited copper in the muscle of tilapia, implying that tilapia cultured under copper polluted environment may be consumed with the visceral tissue discarded. The hepatosomatic index(HSI) of treatment groups was significantly increased compared to that of the control, implying that copper might cause damage to the liver of GIFT tilapia.2.Effects of copper on the antioxidant enzymes in GIFT TilapiaELISA was used to determine the activities of antioxidant enzymes in different tissues(gill, liver, kidney and intestine).of GIFT tilapia. The SOD activity was decreased significantly in the 2 mg/L group in the liver, while it was increased in the kidney of fish in the 2 mg/L group. The CAT activity was the highest in the kidney of fish from the 2 mg/L group.. MDA activity was decreased in the livers of the fish from the 4 mg/L group. There was no significant difference in GSH and GSSG among all tissues between the control and treatment groups. The enzyme activity was altered after exposure to dissolved copper..3. The effects of copper on the expressions of immue-related genes in GIFT TilapiaGene expressions were conducted in the liver and the kidney tissues. RNA was extracted RNA from the liver and the kidney. The expressions of the genes were determined by realtime fluorescence quantitative PCR. The immue-related genes included in this study were IL-1β(interleukin-1 beta), IFN-γ(interferon-gamma), CCL3(Chemokine(C-C motif) ligand 3), TNF-α(tumor necrosis factor-alpha), Hsp70(heat shock protein 70) and MT(metallothionein). The expressions of IL-1β and CCL3(inflammatory reaction related genes) were decreased in the kidney, implying that exposure to copper might cause inflammation in tilapia. The expression of IFN-γ( a pathogen-related gene) was increased, implying that the ability to resist pathogenic microorganisms could be enhanced by copper exposure. Copper exposure did not affect the expression of TNF-α(a tumor factor gene).. The expressions of IL-1β in the liver were increased. The expression of CCL3 and IFN-γ in the liver was inhibited by copper. The expression of MT in the liver was significantly higher than that in the kidney, MT was up-regulated in the liver by copper but down-regulated in the kidney. The expression of Hsp70 was suppressed by copper exposure in the liver.