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Optimization of calcium chloride concentration for removal of polysaccharide contamination during plant DNA isolation
Frnčová, Ekaterina ; Šlosárová, Katarína (referee) ; Fialová, Lenka (advisor)
The greatest difficulty in isolating DNA is the presence of contaminants that cause side effects. Polysaccharides are the most common contaminants in fruits. They can distort the results in spectrophotometric determination of purity or act as inhibitors in PCR analysis together with other substances (for example, proteins or phenolic substances). The aim of this work was to investigate the influence of different concentrations of calcium chloride on the process of DNA isolation. In the experimental part, DNA from the apple was isolated using different concentrations of calcium chloride. The isolation was carried out four times, and each time the sample was adjusted in different ways. It was found that the isolation method used works only with a sample that has been lyophilized. Isolation of DNA from fresh fruit provided very low yields. Probably, this was due to the large water content in the sample, and the proportion of the solid component was smaller. Subsequently, PCR analysis and electrophoresis were performed to determine the amplifiability of the isolated DNA. Two sets of primers with different specificity were used for this analysis. Amplifiability was confirmed only when using primers specific to apple DNA when using 100 mM solution of CaCl2. Other samples have been amplifiable using both types of primers. Probably, samples isolated using a 100 mM solution of CaCl2 had a larger amount of inhibitors that do not affect all PCR reactions equally, which may also indicate a small effectiveness of this amount of CaCl2.
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The influence of polysaccharide contamination on molecular-biology analysis
Žylková, Kateřina ; Strečanská, Paulína (referee) ; Fialová, Lenka (advisor)
The presence of polysaccharides in DNA isolation and its subsequent analysis often leads to undesirable effects. Polysaccharides together with other metabolites (phenolics, proteins) can act as inhibitors of PCR. In this work, the effect of polysaccharide contamination on the analyzed DNA was investigated. In the experimental part, DNA samples were isolated from two exotic fruits (mango, banana), from which the concentration of polysaccharides was then determined. The analysis showed that by adding CaCl2, the polysaccharide content of the samples was significantly lower. After checking the amplification of the DNA samples with added CaCl2, it was found that CaCl2 itself inhibited PCR and therefore had to be removed from the samples. After purification, the amplification of the DNA was reverified and it was found that the DNA with CaCl2 after purification gave the best results. These results were further verified by agarose gel electrophoresis, which confirmed that a reduction in the polysaccharide content of the samples helped DNA amplification. It was also observed that it depends on the type of polysaccharides present in the source plant material. Banana DNA showed better amplification results than mango DNA. This is due to the different chemical composition of these fruits. Banana, unlike mango, does not contain polysaccharides that would significantly contaminate the isolated DNA.
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