Hand 2023 MiP2023

Hand 2023 MiP2023

Oxidative stress and repetitive metabolic transitions: Challenges due to lifestyle of invertebrate extremophiles.

Link: MiP2023 Obergurgl AT

Hand Steven C (2023)

Event: MiP2023 Obergurgl AT

Authors: Arabie D, Hand Steven C

Introduction: Invertebrate extremophiles experience metabolic transitions promoted by diapause, anoxia and extreme dehydration/rehydration [1-3]. For embryos of brine shrimp, Artemia franciscana, these reversible shifts are dramatic with respiration depressed below 1% of active states. Recovery from metabolic disruption in mammals is accompanied by generation of reactive oxygen species (ROS) that cause tissue damage during ischemia-reperfusion [4]. Yet embryos of A. franciscana survive frequent shifts in metabolism, which implies their mitochondria are poised to tolerate such reactivations without accumulation of damaging ROS.
Methods: Mitochondria were isolated [5] and subjected to anoxia for 30 min while controls received continuous normoxia [4]. Samples were pelleted and resuspended in oxygenated buffer containing fresh substrate, ADP and Amplex Red assay components [4]. Parallel samples included auranofin and dinitrochlorobenzene (DNCB) to inhibit thioredoxin reductase and glutathione peroxidase, respectively. Protein carbonyls, aconitase/citrate synthase activity ratios, and lipid hydroperoxides were quantified [4,6].
Results and Discussion: H₂O₂ accumulation did not increase significantly in mitochondria exposed to anoxia-reoxygenation compared to normoxic controls. By comparison, an 8-fold increase in H₂O₂ was reported for rat heart mitochondria given the same treatment [4]. As anticipated, inclusion of auranofin and DNCB statistically increased the H₂O₂ accumulation 2-3 fold in both control and experimental mitochondria. Consistent with the lack of elevated H₂O₂ after anoxia-reoxygenation, aconitase inactivation also was not detected compared to controls. Statistical increases were not observed in protein carbonyls or lipid hydroperoxides. Evidence suggests mitochondria from A. franciscana embryos are well protected against ROS accumulation and oxidative damage during severe metabolic transitions.

1. Hand SC, Denlinger DL, Podrabsky JE, Roy R (2016) Mechanisms of animal diapause: Recent developments from nematodes, crustaceans, insects and fish. https://doi.org/10.1152/ajpregu.00250.2015
2. Hand SC, Menze MA, Borcar A, Patil Y, Covi JA, Reynolds JA, Toner M (2011) Metabolic restructuring during energy-limited states: Insights from Artemia franciscana embryos and other animals. https://doi.org/10.1016/j.jinsphys.2011.02.010
3. Hand SC, Moore DS, Patil Y (2018) Challenges during diapause and anhydrobiosis: mitochondrial bioenergetics and desiccation tolerance. https://doi.org/10.1002/iub.1953
4. Chouchani et al. (2013) Cardioprotection by S-nitrosation of a cysteine switch on mitochondrial Complex I. https://doi.org/10.1038/nm.3212
5. Kwast K, Hand SC (1993) Regulatory features of protein synthesis in isolated mitochondria from Artemia embryos. https://doi.org/10.1152/ajpregu.1993.265.6.R1238
6. Chouchani et al. (2016) Mitochondrial ROS regulate thermogenic energy expenditure and sulfenylation of UCP1. https://doi.org/10.1038/nature17399

Affiliation and acknowledgements

Arabie D, Hand Steven C

Dept Biological Sciences, Louisiana State Univ, Baton Rouge, USA

Corresponding author: shand@lsu.edu.

Funding: NSF grant IOS-1457061/IOS-1456809

Labels:

Stress:Ischemia-reperfusion  Organism: Crustaceans 

Event: E2