The quality of drinking water may be significantly reduced by the presence of cyanobacteria capable of producing toxins, taste, and odor. Several different genera of cyanobacteria are capable of producing microcystin toxins. Moreover, toxin-producing cyanobacteria share specific ribosomal RNA (rRNA) sequences not found in non-toxin-producing strains. Consequently, an rRNA gene probe can be a us...

Intensive growth of cyanobacteria in freshwater promoted by eutrophication can lead to release of toxic secondary metabolites that may harm aquatic organisms and humans. The serine protease inhibitor aeruginosin 828A was isolated from a microcystin-deficient Planktothrix strain. We assessed potential molecular effects of aeruginosin 828A in comparison to another cyanobacterial serine protease i...

Gravity-driven membrane (GDM) ultrafiltration systems require little maintenance: they operate without electricity at ultra-low pressure in dead-end mode and without control of the biofilm formation. These systems are already in use for water purification in some regions of the world where adequate treatment and distribution of drinking water is not readily available. However, many water bodies...

Under some conditions the growth of toxic cyanobacteria must be controlled by treatment with algicidal compounds. Hydrogen peroxide has been proposed as an efficient and relatively safe chemical which can remove cyanobacteria from the environment selectively, without affecting other microorganisms. However, the uncontrolled release of secondary metabolites, including toxins may occur after such...

The protein serine/threonine phosphatases constitute a unique class of enzymes that are critical regulatory enzymes as they must counteract the activities of thousands of protein kinases in human cells. Uncontrolled inhibition of phosphatase activity by toxic inhibitors can lead to widespread catastrophic effects. Over the past decade, a number of natural product toxins have been identified whi...

We postulated that microcystin-sensitive protein phosphatases are integral components of the Chlamydomonas flagellar axoneme, positioned to regulate inner arm dynein activity. To test this, we took a direct biochemical approach. Microcystin-Sepharose affinity purification revealed a prominent 35-kDa axonemal protein, predicted to be the catalytic subunit of type-1 protein phosphatase (PP1c). We...

We investigated the intestinal uptake and adverse effects of microcystins ingested with Microcystis on Daphnia galeata. The gut structure, blood microcystin concentration, appearance, and movements of Daphnia fed Microcystis PCC 7806 or a microcystin-deficient PCC 7806 mutant were monitored over time. Microcystins were rapidly taken up from the digestive cavity into the blood. This process appa...

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Elevated nitrite and microcystin concentrations co-occur during degradation of Microcystis blooms and are toxic to aquatic organisms. We studied the relative and combined effects of these on Daphnia obtusa life-history. Nitrite and microcystin-LR treatments were: 0, 1, 3 mg L(-1) and 0, 10, 100, 300 μg L(-1), respectively. Experiments were factorial with 12 treatment combinations. Incubations w...

Whole transcriptome shotgun sequencing (RNA-seq) was used to assess the transcriptomic response of the toxic cyanobacterium Microcystis aeruginosa during growth with low levels of dissolved inorganic nitrogen (low N), low levels of dissolved inorganic phosphorus (low P), and in the presence of high levels of high molecular weight dissolved organic matter (HMWDOM). Under low N, one third of the ...