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Effect of elevated temperature, darkness, and hydrogen peroxide treatment on oxidative stress and cell death in the bloom-forming toxic cyanobacterium Microcystis aeruginosa

Effect of elevated temperature, darkness, and hydrogen peroxide treatment on oxidative stress and cell death in the bloom-forming toxic cyanobacterium Microcystis aeruginosa
Effect of elevated temperature, darkness, and hydrogen peroxide treatment on oxidative stress and cell death in the bloom-forming toxic cyanobacterium Microcystis aeruginosa
This study assessed the implication of oxidative stress in the mortality of cells of Microcystis aeruginosa Kütz. Cultures grown at 25°C were exposed to 32°C, darkness, and hydrogen peroxide (0.5 mM) for 96 h. The cellular abundance, chl a concentration and content, maximum photochemical efficiency of PSII (Fv/Fm ratio), intracellular oxidative stress (determined with dihydrorhodamine 123 [DHR]), cell mortality (revealed by SYTOX-labeling of DNA), and activation of caspase 3–like proteins were assessed every 24 h. The presence of DNA degradation in cells of M. aeruginosa was also assessed using a terminal deoxynucletidyl transferase-mediated dUTP nick end labeling (TUNEL) assay at 96 h. Transferring cultures from 25°C to 32°C was generally beneficial to the cells. The cellular abundance and chl a concentration increased, and the mortality remained low (except for a transient burst at 72 h) as did the oxidative stress. In darkness, cells did not divide, and the Fv/Fm continuously decreased with time. The slow increase in intracellular oxidative stress coincided with the activation of caspase 3–like proteins and a 15% and 17% increase in mortality and TUNEL-positive cells, respectively. Exposure to hydrogen peroxide had the most detrimental effect on cells as growth ceased and the Fv/Fm declined to near zero in less than 24 h. The 2-fold increase in oxidative stress matched the activation of caspase 3–like proteins and a 40% and 37% increase in mortality and TUNEL-positive cells, respectively. These results demonstrate the implication of oxidative stress in the stress response and mortality of M. aeruginosa.
caspase 3–like activity, cell death, cyanobacteria, darkness, DNA degradation, hydrogen peroxide, Microcystis aeruginosa, oxidative stress, SYTOX-green, temperature, terminal deoxynucletidyl transferase-mediated dUTP nick end labeling
1529-8817
1316-1325
Bouchard, Josée N.
df8f1389-b311-4f1c-8743-ff2b43ff289e
Purdie, Duncan A.
18820b32-185a-467a-8019-01f245191cd8
Bouchard, Josée N.
df8f1389-b311-4f1c-8743-ff2b43ff289e
Purdie, Duncan A.
18820b32-185a-467a-8019-01f245191cd8

Bouchard, Josée N. and Purdie, Duncan A. (2011) Effect of elevated temperature, darkness, and hydrogen peroxide treatment on oxidative stress and cell death in the bloom-forming toxic cyanobacterium Microcystis aeruginosa. Journal of Phycology, 47 (6), 1316-1325. (doi:10.1111/j.1529-8817.2011.01074.x).

Record type: Article

Abstract

This study assessed the implication of oxidative stress in the mortality of cells of Microcystis aeruginosa Kütz. Cultures grown at 25°C were exposed to 32°C, darkness, and hydrogen peroxide (0.5 mM) for 96 h. The cellular abundance, chl a concentration and content, maximum photochemical efficiency of PSII (Fv/Fm ratio), intracellular oxidative stress (determined with dihydrorhodamine 123 [DHR]), cell mortality (revealed by SYTOX-labeling of DNA), and activation of caspase 3–like proteins were assessed every 24 h. The presence of DNA degradation in cells of M. aeruginosa was also assessed using a terminal deoxynucletidyl transferase-mediated dUTP nick end labeling (TUNEL) assay at 96 h. Transferring cultures from 25°C to 32°C was generally beneficial to the cells. The cellular abundance and chl a concentration increased, and the mortality remained low (except for a transient burst at 72 h) as did the oxidative stress. In darkness, cells did not divide, and the Fv/Fm continuously decreased with time. The slow increase in intracellular oxidative stress coincided with the activation of caspase 3–like proteins and a 15% and 17% increase in mortality and TUNEL-positive cells, respectively. Exposure to hydrogen peroxide had the most detrimental effect on cells as growth ceased and the Fv/Fm declined to near zero in less than 24 h. The 2-fold increase in oxidative stress matched the activation of caspase 3–like proteins and a 40% and 37% increase in mortality and TUNEL-positive cells, respectively. These results demonstrate the implication of oxidative stress in the stress response and mortality of M. aeruginosa.

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More information

Published date: 4 November 2011
Keywords: caspase 3–like activity, cell death, cyanobacteria, darkness, DNA degradation, hydrogen peroxide, Microcystis aeruginosa, oxidative stress, SYTOX-green, temperature, terminal deoxynucletidyl transferase-mediated dUTP nick end labeling
Organisations: Ocean Biochemistry & Ecosystems

Identifiers

Local EPrints ID: 207537
URI: https://eprints.soton.ac.uk/id/eprint/207537
ISSN: 1529-8817
PURE UUID: 5d70f006-4a60-4a83-bfc8-eda10a6d528f

Catalogue record

Date deposited: 10 Jan 2012 11:28
Last modified: 16 Jul 2019 23:15

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