Adaptations to Feast and Famine

How is energy and water balance maintained in gorge feeding ectothermic animals and how does energetic status and digestion interact with behavioural responses such as spontaneous activity and preferred body temperature?

Metabolic and functional transitions during feast and famine

(Funded by FNU and in collaboration with Tobias Wang and Hans Malte)

All animals exhibit dynamic changes in the size and functional capacities of the visceral organs that allows the animal to continuously match the energetic maintenance costs to their physiological demands. It is also clear that the transition between feeding and fasting shifts the balance between catabolic and anabolic processes and therefore affect the flow and storage of energy in animals. Our research group focus mainly on ectothermic species that experience large fluctuations in food availability and some of these species are therefore able to rapidly shift “physiological gear” when undergoing the transition from prolonged fasting to gorge feeding. Examples of such animals are large constrictor snakes, tarantulas and fish species such as pikes.

The gastrointestinal organs have high tissue specific metabolism and the phenotypic flexibility of these organs are therefore particularly important for animals rate of energy-absorption (feeding) as well as energy-conservations (Stavation). Thus, the reduction in size and functional capacity of the intestine serves to reduce energy expenditure and prolong survival during food deprivation, but this adaptive strategy obviously relies on the animal being able to swiftly restore the functional capacity of the digestive organs immediately after ingestion of food. The up-regulation of digestive functions, in combination with the various digestive processes and increased protein synthesis result in a considerable rise in metabolism during digestion – Specific Dynamic Action of Food (SDA).

Current areas of research involve:

Determination of energy flow and storage during long term fasting in snakes, spiders and rats. How is metabolic depression linked to organ atrophy and function.

Determination of the SDA response in snakes, spiders and pike and investigations of which central processes that constitute this response (i.e. intestinal growth, acid secretion or protein synthesis)

How does digestive state affect exercise, hypoxia-tolerance and thermal preference? The SDA response in some our study animals constitute the largest increase in oxygen consumption rate that they will experience in their natural settings. It is therefore a possibility that feeding will compromise other capacities such as hypoxia tolerance, activity and thermal preference. It is our aim to understand these interactions better´.