The Mechanisms Of Yeast Respond To Cadmium And Screening Of Cadmium Antagonist

Cadmium is known as a kind of poison metal, which can be enriched in human body easily. Its biological half-life is 10-40 years, and it is very difficult to be eliminated from human body. Cadmium can damage our organs(such as lung, kidney, liver, pancreas, thyroid, heart and bone)and systems(such as nervous system, reproductive system, immune system) in a minute dosage, because of bioaccumulation and biomagnifications. Every year, cadmium emissions in our country is up to 680 tons. The soil and crops polluted by cadmium is increasing which is threatening our food safety and body health.In this paper, Sac charomyces cerevisiae was used as a study model. Four different concentrations of cadmium effects on the growth reproduction and metabolism of Saccharomyces cerevisiae was detected by plate counting method and Flow Cytometry. When cadmium concentration was 320μM, we analyse the expression of Saccharomyces cerevisiae genome with the expression profile sequencing test. Through preliminary screening, we obtain 3 calcium antagonists.1. The plate counting method was used to detect the growth of Saccharomyces cerevisiae effected by cadmium. Results showed that with the concentration of cadmium increased, the growth of Saccharomyces cerevisiae was obviously inhibited.When the concentration of cadmium was 320uM, the growth of Saccharomyces cerevisiae was completely inhibited. Measured by precision acidity meter, with the metal concentration rising, the pH of the culture medium increases. Detected by Flow Cytometry, the concentration of Reactive oxygen species(ROS) and the Mitochondrial membrane potential(△Ψm) are decreased with the increased of cadmium concentration. Detected by microplate reader, the concentration of glutathione (GSH) are increased with the increased of cadmium concentration.2. The Expression profile sequencing results analysis revealed that there are 912 differentially expressed genes. Of these unigenes,415was up-regulated(up to 8.25-fold) and 497was down-regulated(down to 5.37-fold). We identified these results in the National Center for Biotechnology Information database, as determined by BLAST search, with 79 metabolic pathways:Ribosome metabolic pathway, Sulfur metabolic pathway, Oxiditive pressure related metabolic pathway, Vitamin metabolism and aerobic respiration related pathway mostly affected; Biological process (394 avenues). Cellular Compotent (128 avenue) and Molecular Function (725 avenues) was assigned to GO database,25 categories such asTranslation, ribosomal structure and biogenesis pathway(156 DEG)、general function prediction only pathway(107 DEG)、Amino acid transport and metabolism pathway(76 DEG) was assigned to clusters of orthologous groups (COG).3. Saccharomyces cerevisiae as a model to study the antagonistic activity of zinc, iron, selenium. The results showed that when the cadmium concentration were 40μM and 160μM, the addition of zinc, iron, selenium had a significant effect on the yeast growth, respectively. When cadmium concentrations were 40μM and 160μM, the zinc, selenium, iron optimal concentrations were 120μM,15μM,5μM; 320μM,120μM,30μM, respectively. The addition of zinc, iron, selenium had no significant effect on the yeast growth when cadmium concentrations were 80μM and 320μM. The addition of magnesium had no effects on cadmium toxicity.The expression profile sequencing analysis revealed the mechanism of yeast response to cadmium in gene level, providing a reference for the selection of targets for the cadmium toxicity diseases; cadmium antagonist screening provide a drug reference for the treatment of cadmium toxicity diseases on clinical.