The Effects of anatoxin-a and cylindrospermopsin at different nitrogen concentrations and photon irradiances on the physiology of Microcystis aeruginosa (Cyanobacteria) and Scenedesmus acuminatus (Chlolrophyta)
Interactions between cyanobacteria and their environment result in the production of secondary metabolites that are classified as being allelochemicals and toxins. These are geared towards ensuring their cell proliferation in the aquatic system and out competing neighboring micro- and macro-plants and cyanobacteria for available nutrients and space. Among the cyanotoxins produced by species of cyanobacteria, cylindrospermopsin (CYN) and anatoxin-a (ATX) have been the least studied with regards to their effects on other algae under different biotic and abiotic environmental conditions. This study will investigate the effects of CYN and ATX on the growth, biomass production and antioxidant enzyme activities of Microcystis aeruginosa (BCCUSP232) and Scenedesmus acuminatus (UFSCar036), and microcystins (MCs) production by M. aeruginosa under different nitrogen (0.04 to 9 mM NaNO3) concentrations and photon irradiances (10 and 40 µmol photons m-2 s-1). Four different experiments will be carried out. In the first and second experiments, the effects of pure ATX at environmentally relevant concentrations on M. aeruginosa and S. acuminatus under varying nitrogen concentrations and photon irradiances will be studied. The third and fourth experiments will determine how CYN influences the growth and physiology of M. aeruginosa and S. acuminatus under different N concentrations and photon irradiances. The results of this project will enhance our current understanding of how cyanotoxins influence cyanobacterial and microalgal physiology under varying environmental conditions using realistic and environmentally relevant concentrations of the toxins, as well as the establishment of the possible influence of ATX and CYN on MCs production by M. aeruginosa.
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