The Individual and Combined Effects of the Cyanotoxins, Anatoxin-a and Microcystin-LR, on the Growth, Toxin Production, and Nitrogen Fixation of Prokaryotic and Eukaryotic Algae

Autor(es)

Chia, Mathias Ahii ^{[1, 2, 3]} ; Kramer, Benjamin J. ^[2] ; Jankowiak, Jennifer G. ^[2] ; Bittencourt-Oliveira, Maria do Carmo ^[3] ; Gobler, Christopher J. ^[2]

Afiliação do(s) autor(es)

^[1] Ahmadu Bello Univ, Dept Bot, Zaria 810001 - Nigeria

^[2] SUNY Stony Brook, Sch Marine & Atmospher Sci, Southampton, NY 11968 - USA

^[3] Univ Sao Paulo, Luiz de Queiroz Coll Agr, Dept Biol Sci, Ave Padua Dias 11, BR-13418900 Piracicaba, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: TOXINS; v. 11, n. 1 JAN 2019.
• Citações Web of Science: 2

Resumo

Globally, eutrophication and warming of aquatic ecosystems has increased the frequency and intensity of cyanobacterial blooms and their associated toxins, with the simultaneous detection of multiple cyanotoxins often occurring. Despite the co-occurrence of cyanotoxins such as microcystins and anatoxin-a (ATX) in water bodies, their effects on phytoplankton communities are poorly understood. The individual and combined effects of microcystin-LR (MC-LR) and ATX on the cyanobacteria Microcystis spp., and Anabaena variabilis (a.k.a. Trichormus variabilis), and the chlorophyte, Selenastrum capricornutum were investigated in the present study. Cell density, chlorophyll-a content, and the maximum quantum efficiency of photosystem II (Fv/Fm) of Microcystis cells were generally lowered after exposure to ATX or MC-LR, while the combined treatment with MC-LR and ATX synergistically reduced the chlorophyll-a concentration of Microcystis strain LE-3. Intracellular levels of microcystin in Microcystis LE-3 significantly increased following exposure to MC-LR + ATX. The maximum quantum efficiency of photosystem II of Anabaena strain UTEX B377 declined during exposure to the cyanotoxins. Nitrogen fixation by Anabaena UTEX B377 was significantly inhibited by exposure to ATX, but was unaffected by MC-LR. In contrast, the combination of both cyanotoxins (MC-LR + ATX) caused a synergistic increase in the growth of S. capricornutum. While the toxins caused an increase in the activity of enzymes that scavenge reactive oxygen species in cyanobacteria, enzyme activity was unchanged or decreased in S. capricornutum. Collectively this study demonstrates that MC-LR and ATX can selectively promote and inhibit the growth and performance of green algae and cyanobacteria, respectively, and that the combined effect of these cyanotoxins was often more intense than their individual effects on some strains. This suggests that the release of multiple cyanotoxins in aquatic ecosystems, following the collapse of blooms, may influence the succession of plankton communities. (AU)

• Processo FAPESP: 13/11306-3 - Efeitos de anatoxina-a e cilindrospermopsina em diferentes concentrações de nitrogênio e irradiância na fisiologia de Microcystis aeruginosa (Cyanobacteria)e Scenedesmus acuminatus (Chlorophyta)
• Beneficiário: Mathias Ahii Chia
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 14/26898-6 - Revelando alguns processos fisiológicos e moleculares envolvidos nas interações alelopáticas entre fitoplâncton tóxico e não-tóxicos
• Beneficiário: Mathias Ahii Chia
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado