Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

The determination of microcystin producing gene in Microcystis spp.

Microcystins are biotoxins, also called seconder metobolites, produced by cyanobacteria and caused various problems in human health and other living organisms. The main producers of microcystin are Microcystis, Planktothrix, Anabaenopsis, Anabaena, Oscillatoria. Countries with Mediterranean climate have intensive blooms of Microcystis spp., and therefore microcystin accumulation, particularly in summer to mid autumn. As a result, ecologic and economic value reduction, habitat losses and deaths of several organisms can be seen in aquatic ecosystems.

The investigation of mechanisms of cyanotoxin production in the cell in molecular and genetic grade will help us to develop early warning systems and take precautions for blooms which are especially present in drinking water reservoirs, lakes and lagunar sites.

In this study, not only the determination of toxin genes but also the investigation of variations in mcyB genes, as a molecular indicator, are aimed. Because, variations in mcyB genes can alter microcystin structure and increase toxicity.

mcyB gene amplified by PCR-base methods. Then enzyme cutting, SSCP (Single-Strand Conformation Polymorphism) and sequence analysis studied. As a result, it was found that many parts of the mcyB gene has many variations. These variations especially are single nucleotid mutations and they caused silent mutations. At the same time amino acid changes were seen, however, not in conserved sequence motifs. Therefore, it has been thought that they have no effect on microcystin toxicity. However, to understand roles of amino acid changes and single nucleotid mutations, which are excepting of conserved sequence motifs, more detailed investigations should be done.