Metabolic regulation during seasonal adaptation

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Auditorium F101 of the Faculty of Biochemistry and Molecular Medicine (Aapistie 7)

Topic of the dissertation

Metabolic regulation during seasonal adaptation

Doctoral candidate

Master of Science Laura Niiranen

Faculty and unit

University of Oulu Graduate School, Faculty of Medicine, Research Unit of Biomedicine

Subject of study

Physiology

Opponent

Professor Jan Tuckermann, University of Ulm

Custos

Professor Karl-Heinz Herzig, University of Oulu

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Metabolic regulation during seasonal adaptation

Animal species that inhabit the higher latitudes utilize various mechanisms to survive the challenging seasons of cold and sparse food sources. This thesis work examines metabolic regulation in two animal models with seasonal adaptations.

The raccoon dog is a canid species originating from East Asia that has been introduced to several areas in Europe and is efficiently dispersing. Genetic changes that have enabled the adaptation to new environments were evaluated by comparing the transcriptome profiles of raccoon dogs from the original habitation areas in South Korea and Japan to the more recent introduction area in Finland. The results revealed novel aspects on the history of the raccoon dog and on the genes that might have aided in the diversification process.

During the cold winter season, the raccoon dog can enter a state of winter lethargy, characterized by reduced activity and modest body temperature reduction. The role of thermoregulation in the energy homeostasis was evaluated, and our results demonstrated a lack of BAT and UCP1-dependent thermogenesis in the adult raccoon dog, indicating resilience to cold weather.

The reindeer is a semi-domesticated ruminant species that spends the winter actively foraging for food sources. The transcriptome profiles were compared along with metabolic and thermoregulatory markers from reindeer populations in Finland and Siberia at different seasons. Our results identified candidate genes involved in the immune response, fat deposition, and energy metabolism as well as the potential for UCP1-dependent thermogenesis in the adipose tissue, which have potentially contributed to the adaptation to arctic environments.

Raccoon dogs prepare for winter by seasonal hyperphagia and can survive long periods of fasting relying on the accumulated adipose tissues. These opposite conditions were studied, and the results revealed that the studied key central and peripheral regulatory peptides and plasma metabolic profiles remained similar after autumnal fattening and winter fasting.

The adaptive changes in the physiology and metabolism make seasonally adaptive animal species promising targets for further studies on the mechanisms regulating metabolism and on the roles of adipose tissue.
Last updated: 19.5.2022