chemistry and cyanobacteria

Direct measurements from reservoir water (temperature, oxygen concentration, pH and conductivity) in the reservoir were performed at 14 stations located along 10 parallel transects established for hydroacoustic surveys.
A YSI ProODO Digital Professional Series (Ohio, USA) meter with an optical oxygen sensor and a WTW Multi 3420 (Weilheim, Germany) meter were used for in-situ measurements of the basic physico-chemical parameters (temperature, oxygen concentration, pH). Temperature and oxygen concentration were measured once per meter, from the surface to the bottom. The results are presented as the mean values calculated separately for each sampling station. pH was measured once at every sampling station in unified water samples.
Genetic analyzes of cyanobacteria
The samples of water for DNA assays (always 100 mL of water was collected) were prepared according to Mankiewicz-Boczek et al. (2006). Filters with cyanobacterial material (pore diameter 0.45 ?m, Millipore, USA) were put into the lysis buffer containing 40 mM EDTA, 400 mM NaCl, 0.75 M sucrose, and 50 mM TRIS-HCl (pH 8.3) and frozen as soon as possible. Genetic material was extracted from the filters according to Giovannoni et al. (1990), with some modifications, which improved the extracted DNA quality and quantity, as described by Mankiewicz-Boczek et al. (2006).
?Extracted DNA was used as the template for quantitative (qRT-PCR, quantitative real-time PCR) determination of: the 16S rRNA (250 bp) gene fragment specific for the genus Microcystis

and the mcyA (395 bp) gene fragment specific for toxic Microcystis genotypes.
Chromatographic analyzes of microcystins
For high-performance liquid chromatography (HPLC) analyzes, 1-L water samples
containing cyanobacterial material were filtered through GF/C filters (Whatman, Kent, UK GF/C, 1.20 ?m) immediately after sampling. The preparation of cyanobacterial material and the determination of MCs concentration via HPLC-DAD were performed according to Jurczak et al. (2005).
Protein phosphatase inhibition assay
The protein phosphatase inhibition assay was performed with a MicroCystest screening immuno-bioassay (ZEU-Inmunotec, Zaragoza, Spain) to confirm the biological activity of MCs, i.e. their toxicity.