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Oxidative Medicine and Cellular Longevity
Volume 2019, Article ID 6840540, 14 pages
https://doi.org/10.1155/2019/6840540
Research Article

Mitochondrial Oxidative Stress Impairs Energy Metabolism and Reduces Stress Resistance and Longevity of C. elegans

1Institute of Nutritional Sciences, Laboratory for Nutrition in Prevention and Therapy, Biomedical Research Center Seltersberg (BFS), Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
2Molecular Nutrition Research, Interdisciplinary Research Center, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany
3Imaging Unit, Biomedical Research Center Seltersberg (BFS), Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany

Correspondence should be addressed to Gunter P. Eckert; ed.nesseig-inu@trekce

Received 6 August 2019; Revised 8 October 2019; Accepted 22 October 2019; Published 15 November 2019

Academic Editor: Ravirajsinh Jadeja

Copyright © 2019 Benjamin Dilberger et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Introduction. Mitochondria supply cellular energy and are key regulators of intrinsic cell death and consequently affect longevity. The nematode Caenorhabditis elegans is frequently used for lifespan assays. Using paraquat (PQ) as a generator of reactive oxygen species, we here describe its effects on the acceleration of aging and the associated dysfunctions at the level of mitochondria. Methods. Nematodes were incubated with various concentrations of paraquat in a heat-stress resistance assay (37°C) using nucleic staining. The most effective concentration was validated under physiological conditions, and chemotaxis was assayed. Mitochondrial membrane potential (ΔΨm) was measured using rhodamine 123, and activity of respiratory chain complexes determined using a Clark-type electrode in isolated mitochondria. Energetic metabolites in the form of pyruvate, lactate, and ATP were determined using commercial kits. Mitochondrial integrity and structure was investigated using transmission electron microscopy. Live imaging after staining with fluorescent dyes was used to measure mitochondrial and cytosolic ROS. Expression of longevity- and mitogenesis-related genes were evaluated using qRT-PCR. Results. PQ (5 mM) significantly increased ROS formation in nematodes and reduced the chemotaxis, the physiological lifespan, and the survival in assays for heat-stress resistance. The number of fragmented mitochondria significantly increased. The ∆Ψm, the activities of complexes I-IV of the mitochondrial respiratory chain, and the levels of pyruvate and lactate were significantly reduced, whereas ATP production was not affected. Transcript levels of genetic marker genes, atfs-1, atp-2, skn-1, and sir-2.1, were significantly upregulated after PQ incubation, which implicates a close connection between mitochondrial dysfunction and oxidative stress response. Expression levels of aak-2 and daf-16 were unchanged. Conclusion. Using paraquat as a stressor, we here describe the association of oxidative stress, restricted energy metabolism, and reduced stress resistance and longevity in the nematode Caenorhabditis elegans making it a readily accessible in vivo model for mitochondrial dysfunction.