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Developmental significance of cyanide‐resistant respiration under stressed conditions: Experiments in Dictyostelium cells
Author(s) -
Kimura Kei,
Kuwayama Hidekazu,
Amagai Aiko,
Maeda Yasuo
Publication year - 2010
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.2010.01200.x
Subject(s) - incubation , respiration , dictyostelium , biology , null cell , vacuole , cellular respiration , biochemistry , alternative oxidase , metabolism , microbiology and biotechnology , botany , gene , cytoplasm
We have previously reported that benzohydroxamic acid (BHAM), a potent inhibitor of cyanide (CN)‐resistant respiration mediated by alternative oxidase (AOX), induces formation of unique cell masses (i.e., stalk‐like cells with a large vacuole and thick cell wall) in starved Dictyostelium cells. Unexpectedly, however, aox ‐null cells prepared by homologous recombination exhibited normal development under normal culture conditions on agar, indicating that BHAM‐induced stalk formation is not solely attributable to inhibition of CN‐resistant respiration. This also suggests that a series of pharmacological approaches in the field of life science has serious limitations. Under stress (e.g., in submerged culture), starved aox ‐null cells exhibited slightly delayed aggregation compared with parental Ax‐2 cells; most cells remained as loose aggregates even after prolonged incubation. Also, the developmental defects of aox ‐null cells became more marked upon incubation for 30 min just after starvation in the presence of ≥1.75 mmol/L H 2 O 2 . This seems to indicate that CN‐resistant respiration could mitigate cellular damage through reactive oxygen species (ROS), because AOX has a potential role in reduction of ROS production. Starved aox ‐null cells did not develop in the presence of 5 mmol/L KCN (which completely inhibited the conventional cytochrome‐mediated respiration) and remained as non‐aggregated single cells on agar even after prolonged incubation. Somewhat surprisingly, however, parental Ax‐2 cells were found to develop normally, forming fruiting bodies even in the presence of 10 mmol/L KCN. Taken together, these results suggest that CN‐resistant respiration might compensate for the production of adenosine tri‐phosphate via oxidative phosphorylation.