Small mammals actively decrease metabolism during daily torpor and hibernation to save energy. Recently, depression of mitochondrial substrate oxidation in isolated liver mitochondria was observed and associated to hypothermic/hypometabolic states in Djungarian hamsters, mice and hibernators. We aimed to clarify whether hypothermia or hypometabolism causes mitochondrial depression during torpor by studying the Golden spiny mouse (Acomys russatus), a desert rodent which performs daily torpor at high ambient temperatures of 32°C. Notably, metabolic rate but not body temperature is significantly decreased under these conditions. In isolated liver, heart, skeletal muscle or kidney mitochondria we found no depression of respiration. Moderate cold exposure lowered torpor body temperature but had minor effects on minimal metabolic rate in torpor. Neither decreased body temperature nor metabolic rate impacted mitochondrial respiration. Measurements of mitochondrial proton leak kinetics and determination of P/O ratio revealed no differences in mitochondrial efficiency. Hydrogen peroxide release from mitochondria was not affected. We conclude that interspecies differences of mitochondrial depression during torpor do not support a general relationship between mitochondrial respiration, body temperature and metabolic rate. In Golden spiny mice, reduction of metabolic rate at mild temperatures is not triggered by depression of substrate oxidation as found in liver mitochondria from other cold-exposed rodents.

Endothermy has facilitated mammalian species radiation, but the sequence of events leading to sustained thermogenesis is debated in multiple evolutionary models. Here we study the Lesser hedgehog tenrec (Echinops telfairi), a phylogenetically ancient, 'protoendothermic' eutherian mammal, in which constantly high body temperatures are reported only during reproduction. Evidence for nonshivering thermogenesis is found in vivo during periodic ectothermic-endothermic transitions. Anatomical studies reveal large brown fat-like structures in the proximity of the reproductive organs, suggesting physiological significance for parental care. Biochemical analysis demonstrates high mitochondrial proton leak catalysed by an uncoupling protein 1 ortholog. Strikingly, bioenergetic profiling of tenrec uncoupling protein 1 reveals similar thermogenic potency as modern mouse uncoupling protein 1, despite the large phylogenetic distance. The discovery of functional brown adipose tissue in this 'protoendothermic' mammal links nonshivering thermogenesis directly to the roots of eutherian evolution, suggesting physiological importance prior to sustained body temperatures and migration to the cold.

Small mammals actively decrease metabolism during daily torpor and hibernation to save energy. Increasing evidence suggests depression of mitochondrial respiration during daily torpor of the Djungarian hamster but tissue-specificity and relation to torpor depth is unknown. We first confirmed a previous study by Brown and colleagues reporting on the depressed substrate oxidation in isolated liver mitochondria of the Djungarian hamster (Phodopus sungorus) during daily torpor. Next, we show that mitochondrial respiration is not depressed in kidneys, skeletal muscle and heart. In liver mitochondria, we found that state 3 and state 4 respirations correlate with body temperature, suggesting inhibition related to torpor depth and to metabolic rate. We conclude that molecular events leading to depression of mitochondrial respiration during daily torpor are specific to liver and linked to a decrease in body temperature. Different tissue-specificity of mitochondrial depression may assist to compare and identify the molecular nature of mitochondrial alterations during torpor.

Golden spiny mice (Acomys russatus) living in the Judean desert are exposed to extended periods of food and water shortage. We investigated their thermal and metabolic response to three weeks of 50% food reduction at ambient temperatures of 23, 27, 32 and 35 °C by long term records of metabolic rate and body temperature in the laboratory. At all ambient temperatures, A. russatus responded to starvation by a reduction of daily energy expenditure. At 32 and 35 °C, this metabolic adjustment fully compensated the reduced food availability and they maintained their energy balance at a slightly reduced body mass. At lower ambient temperatures, they could not fully compensate for the reduced food availability and kept a negative energy balance. The reduction of daily energy expenditure was largely achieved by the occurrence of daily torpor. Torpor even occurred at high ambient temperatures of 32 and 35 °C during which metabolic depression was not associated with a marked decrease of body temperature. The results show that the occurrence of daily torpor is not necessarily linked to cold exposure and the development of a pronounced hypothermia, but may even occur as depression of metabolic rate in a hot environment.

In the wild, Alpine marmots (Marmota marmota) spend most of their time in underground burrows. Thus the observation of reproduction biology during mating season, gestation, and the early juvenile development is extremely challenging. An ultrasonographic follow-up of pregnancies in captive alpine marmots illustrates the characteristic findings of different gestational phases. The first ultrasonographic proof for a pregnancy was detected on day -25 (day 0 defined as partus). At day -18, first heartbeats were visualized, followed by spontaneous fetal movements on day -14. At day -7, the mineralization of the skeletal system was demonstrated. It was possible to evaluate and monitor the integrity of pregnancy. Ultrasonography is a noninvasive, alternative tool to the classical verification of pregnancy in marmots by progesterone measurement from serum samples.

Life science disciplines may necessitate the use of animals in research and education. The most important requisite in animal experimentation is that scientists and their personnel are well trained, cautious and sensitive to the needs of the animals. Currently there are no obligatory training guidelines and available training differs greatly between institutions. The aim of this project is to develop an e-learning program which will be adaptable to different aspects and study focuses to assist in the progress of harmonising specialist education, currently with emphasis on German guidelines and regulations. A future perspective will be to assist in international harmonisation of the humane treatment of experimental animals. Content and complexity will be in accordance with the FELASA guidelines. Video and picture material will serve to communicate theoretical and practical considerations of experimental animal work and will help to sensitise young scientists for humane handling of animals in research. Thus computer assisted learning (CAL) will be a valuable tool to mediate knowledge through animation and simulation; and to open new ways of communicating important questions in laboratory animal sciences. The future focus of the e-learning program will be on the application of the 3Rs in experimental protocols.