Metabolic Transition in Caenorhabditis elegans Dauer Larva

• Main Author: Kaptan, Damla
• Other Authors: Technische Universität Dresden, Fakultät Mathematik und Naturwissenschaften
• Format: Doctoral Thesis
• Language: English
• Published: Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden 2017
• Subjects: Caenorhabditis elegans; dauer; metabolism; aging; lithium; ddc:570; rvk:WG 8701
• Online Access: http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-223034; http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-223034; http://www.qucosa.de/fileadmin/data/qucosa/documents/22303/Thesis_Damla_Kaptan_20170319.pdf

Under unfavorable environmental conditions Caenorhabditis elegans larvae enter a dauer stage which is a specialized non-feeding larval stage. In the dauer stage, worms display astonishingly low metabolism, which allows them to adapt themselves to environmental stress and to dwell without food for several months. Dauer larvae can enter into the reproductive larval stage, when environmental conditions become favorable. In this study, the metabolic transition of dauers into the reproductive larval stage is analyzed in detail: a. During the exit of dauers, several metabolic traits were examined. Primarily, dauer larva initiates the metabolic transition by activating feeding, which is followed by upregulated oxygen consumption and mitochondrial remodeling, as well as enhanced protein synthesis. b. To better understand the metabolic transition, inhibitors of the dauer exit were introduced. Lithium ions were shown to inhibit the transition of dauers to reproductive larvae and prevent the upregulation of metabolic activities required for this process. c. In liquid culture, the transition from the dauer to the reproductive larva is also inhibited, presumably because of the hypoxic character of the liquid culture. Thus, hypoxia has a negative effect on the metabolic transition. d. In the course of our investigation we discovered that the dauer larva is not a closed system but indeed, it can dwell on the externally available ethanol as a carbon source by incorporating it into the energy metabolism. This allows dauers to survive for longer periods in the absence of bacteria, the preferred food of worms. These findings clarify the nature of dauers, how they utilize distinct pathways during the metabolic transition and how they take advantage of the externally available carbon source. These results may in the future enable us to elucidate the complex pathways of metabolism, as well as the ways in which it can be regulated.