RESUMEN
Cylindrospermopsin (CYN) is a cyanobacterial toxin known as a eukaryotic protein synthesis inhibitor. We aimed to study its effects on growth, stress responses and mitosis of a eukaryotic model, Vicia faba (broad bean). Growth responses depended on exposure time (3 or 6d), cyanotoxin concentration, culture conditions (dark or continuous light) and V. faba cultivar ("Standard" or "ARC Egypt Cross"). At 6d of exposure, CYN had a transient stimulatory effect on root system growth, roots being possibly capable of detoxification. The toxin induced nucleus fragmentation, blebbing and chromosomal breaks indicating double stranded DNA breaks and programmed cell death. Root necrotic tissue was observed at 0.1-20 µg mL(-1) CYN that probably impeded toxin uptake into vascular tissue. Growth and cell death processes observed were general stress responses. In lateral root tip meristems, lower CYN concentrations (0.01-0.1 µg mL(-1)) induced the stimulation of mitosis and distinct mitotic phases, irrespective of culture conditions or the cultivar used. Higher cyanotoxin concentrations inhibited mitosis. Short-term exposure of hydroxylurea-synchronized roots to 5 µg mL(-1) CYN induced delay of mitosis that might have been related to a delay of de novo protein synthesis. CYN induced the formation of double, split and asymmetric preprophase bands (PPBs), in parallel with the alteration of cell division planes, related to the interference of cyanotoxin with protein synthesis, thus it was a plant- and CYN specific alteration.
Asunto(s)
Toxinas Bacterianas/toxicidad , Toxinas Marinas/toxicidad , Microcistinas/toxicidad , Mitosis/efectos de los fármacos , Uracilo/análogos & derivados , Vicia faba/efectos de los fármacos , Alcaloides , Muerte Celular/efectos de los fármacos , Cromosomas de las Plantas/efectos de los fármacos , Cromosomas de las Plantas/ultraestructura , Toxinas de Cianobacterias , Citoesqueleto/efectos de los fármacos , Citoesqueleto/metabolismo , Egipto , Meristema/citología , Meristema/efectos de los fármacos , Meristema/metabolismo , Índice Mitótico , Proteínas de Plantas/biosíntesis , Raíces de Plantas/citología , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Uracilo/toxicidad , Vicia faba/citología , Vicia faba/metabolismoRESUMEN
Waterbloom samples of Microcystis aeruginosa and Planktothrix agardhii were collected from a variety of ponds, lakes and reservoirs in Hungary. Samples were tested with matrix-assisted laser desorption/ionization - time-of-flight mass spectrometry (MALDI-TOF MS) to identify the microcystin forms. The concentration of the microcystins was measured with capillary electrophoresis and the toxicity was tested by sinapis test. DNA was extracted from the samples and tested using a range of primers linked to the biosynthesis of microcystin. All of the fourteen collected samples gave positive results for the presence of the mcy genes with PCR products with sizes between of 425 and 955 bp, respectively, indicating the presence of the genes implicated in the production of microcystins. The results showed that a wide range of microcystin (MC) forms were detected in the Microcystis containing samples, among which MC-LR, -RR, and -YR were the most common. The highest MC concentration was 15,701 mg g-1, which was detected in an angling pond. The samples containing Planktothrix agardhii were less toxic, and the most common form in this species was the Asp3-MC-LR.