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Formerly bile-farmed bears show the same sort of lifestyle-related pathologies that are also responsible for accelerated, premature ageing in humans. This is the main finding of an international study led by researchers from the University of Veterinary Medicine Vienna. According to the study, bile-farmed bears show clear parallels to a number of diseases in humans caused in both cases by the harmful effects of their respective lifestyles.

For their study, the researchers investigated the long-term effects of chronic inflammation in 42 Asiatic black bears (Ursus thibetanus) rescued from Vietnamese bile farms. The bears were examined under anaesthesia and treated at least twice as part of essential medical interventions. All bears were diagnosed with chronic low-grade sterile or bacterial hepatobiliary inflammation along with other pathologies.

Findings from studies of rescued bile-farmed bears as a model of lifestyle-related diseases in humans

“Chronic inflammation, in conjunction with poor living conditions and chronic stress, appears to increase the risk of developing degenerative diseases such as obese sarcopenia (low muscle mass and strength), chronic kidney disease and impaired cardiovascular function. These disorders are a sign of accelerated ageing. The phenotype (appearance) of bile-farmed bears contrasts markedly with the healthy phenotype of wild hibernating bears,” says first author Szilvia K. Kalogeropoulu from the Research Institute of Wildlife Ecology at Vetmeduni.

The insights gained extend far beyond the animals studied, as last author and project supervisor Johanna Painer-Gigler from the Research Institute of Wildlife Ecology explains: “The pathological parallels with inflammageing and immunosenescence – the gradual decline in immune function – in humans suggests that the insights gained from bile-farmed bears could serve as a model to investigate the pathophysiology and harmful effects of lifestyle-related diseases. This would allow us to look at these pathologies from a broader perspective and hopefully gain a better understanding of them.”

Biomimetics – inspired by nature, of benefit for animals and humans

The researchers identified these similarities using a biomimetic approach, i.e. by drawing inspiration from nature. In the medical context, biomimetic studies of wild animals are useful for identifying mechanisms that protect against the age-related burden of lifestyle diseases or, as shown in this study, to increase susceptibility to them. The bioinspired approach could offer novel opportunities for the development of medical treatments and drugs for both humans and animals. Biomimetics allows researchers to learn from nature, compare different findings between animals and humans, and create knowledge that is not based on animal experiments but on comparative medicine. For the present study, hibernating free-ranging bears, as a healthy control group, served as bioinspiration due to their mechanisms that protect them from the burden of lifestyle diseases that accumulate in humans with age. These include muscle wasting, osteoporosis, vascular disease and chronic kidney disease. Hibernation, as an evolutionary adaptation, has generally made bears more resilient against organ damage and metabolic disorders. Bile-farmed bears, on the other hand, which are kept in suboptimal and unnatural living conditions, do not exhibit the same level of resilience and therefore show similar pathologies as seen in humans living an unhealthy lifestyle.

The article “Formerly bile-farmed bears as a model of accelerated ageing” by Szilvia K. Kalogeropoulu, Hanna Rauch-Schmücking, Emily J. Lloyd, Peter Stenvinkel, Paul G. Shiels, Richard J. Johnson, Ole Fröbert, Irene Redtenbacher, Iwan A. Burgener and Johanna Painer-Gigler was published in Scientific reports.

Scientific article

2023-07-06

How does climate change impact animals that hibernate? A team of researchers from the University of Veterinary Medicine Vienna looked into this question using an experimental set-up. The study revealed that garden dormice (Eliomys quercinus) are quite capable of adapting to warmer climatic conditions – provided that enough food is available.

Torpor, including hibernation, is an energy-saving strategy used by many animals during the cold season. Climate change impacts this period of reduced metabolic rate and body temperature by increasing the frequency of periodic rewarming, which is characterised by high levels of oxidative stress and is associated with a shortening of the telomeres – the protective caps at the ends of the chromosomes that become shorter with each cell division and are essentially responsible for ageing.

Aim of the study: to investigate feeding behaviour and telomere dynamics during hibernation

Against this background, the researchers investigated the impact of ambient temperature on feeding behaviour and telomere dynamics in garden dormice. This small nocturnal mammal prepares for hibernation by accumulating fat reserves but also eats during hibernation. Food intake, torpor pattern, changes in telomere length, and body mass change were measured in animals kept at experimentally controlled temperatures of either 14 °C (a mild winter) or 3 °C (a cold winter) over a period of six months.

Higher temperatures interfere with hibernation; animals compensate through increased food intake

When hibernating at 14 °C, garden dormice experienced 1.7-fold more frequent and 2.4-fold longer periods of arousal compared to animals hibernating at 3 °C. “Higher food intake enabled individuals to compensate for increased energetic costs when hibernating at milder temperatures, to buffer body mass loss and so increase winter survival,” explains co-first author Marie-Therese Ragger from the Research Institute of Wildlife Ecology at Vetmeduni.

Telomeres significantly elongated regardless of temperature

Interestingly, the researchers observed a significant increase in telomere length over the entire hibernation period, regardless of temperature. According to study co-first author Sylvain Giroud (Research Institute of Wildlife Ecology at Vetmeduni), the research team therefore concludes that “even higher temperatures during winter, if associated with sufficient food availability, can have a positive effect on the individual’s energy balance and somatic maintenance. These results suggest that winter food availability might be a crucial determinant for the survival of the garden dormouse in the context of ever-increasing environmental temperatures.”

The article “Food availability positively affects the survival and somatic maintenance of hibernating garden dormice (Eliomys quercinus)” by Sylvain Giroud, Marie-Therese Ragger, Amélie Baille, Franz Hölzl, Steve Smith, Julia Nowack and Thomas Ruf was published in Frontiers in Zoology.

Scientific article

2023-07-03

Winters in northern latitudes are harsh. To survive food shortages and cold, many birds and mammals reduce their energy requirements in winter by lowering their metabolism (hypometabolism) and body temperature. This phenomenon is especially known from hibernators. It is controlled by photoperiod - that is, by changes in day and night length. However, the extent of hypometabolism and the decrease in body temperature in hibernators is also influenced by diet, namely by the intake of essential polyunsaturated fatty acids. A team from the University of Veterinary Medicine Vienna has now investigated whether similar effects can also be found in non-hibernating large mammals, using red deer. The study was published as a cover story in the renowned journal "Animals".

With their experimental study, the research team confirms for the first time that seasonal changes in body temperature and the resulting low energy consumption are controlled by the same mechanism in non-hibernating mammals as in hibernators - namely by changes in the photoperiod.

Melatonin and food as experimental triggers

To test this, the researchers fed adult female red deer (Cervus elaphus) pellets enriched with linoleic or linolenic acid and simulated periods of abundant and restricted food supply. The key experiment on the role of photoperiod in physiological and behavioural seasonal changes was the artificial supply of melatonin in summer, a hormone that is naturally secreted during the daily dark phase and that translates day length into a physiological signal. The deer were equipped with data loggers that recorded heart rate, body temperature and locomotor activity. In addition, the animals were regularly weighed and their daily intake of feed pellets was measured.

Short days are essential for physiological changes

"By experimentally increasing the amount of melatonin already in early summer to levels about three times higher than the winter peak, we induced a winter phenotype in all measured traits weeks in advance. We conclude that red deer reduce their energy expenditure for thermoregulation during short day lengths, a reaction that is enhanced by a restricted food supply," explains study leader Walter Arnold of the Research Institute of Wildlife Ecology (FIWI) at the Vetmeduni. In contrast, the supply of essential fatty acids in the diet only marginally influenced the seasonal adaptation of red deer.

Comprehensive mechanism operating in many animal species

Scientifically, it is known that numerous species inhabiting regions with severe winters exhibit seasonal cycles of physiological and behavioural traits, with low points in winter. "It appears that these cycles are ubiquitously controlled by an ancient endogenous rhythm that is seasonally synchronized by photoperiod. This mechanism is responsible for the timely preparation for the profound change in living conditions caused by the seasons, not only in hibernators but also in many other species," said Walter Arnold.

The article "The Influence of Photoperiod, Intake of Polyunsaturated Fatty Acids, and Food Availability on Seasonal Acclimatization in Red Deer (Cervus elaphus)" by Kristina Gasch, Manuela Habe, Julie Sophie Krauss, Johanna Painer-Gigler, Gabrielle Stalder, and Walter Arnold was published in Animals.

Wissenschaftlicher Artikel

2023-06-15

If one compares the torpor of different animal species, two different patterns emerge. A recently published Australian–Austrian study led by the University of Veterinary Medicine Vienna investigated how this difference affects the long-term survival of the animals. The researchers conclude that not all torpor is the same and that the ability to enter a state of decreased physiological activity probably evolved for different reasons in different species.

Torpor is a highly effective method in mammals and birds to reduce energy expenditure. The extent of energy savings achieved, however, and thus the long-term survival of the animals, appears to differ among species. Animals that remain in a state of torpor for several days at a time (hibernation) seem to have an advantage over daily heterotherms, which are species that remain torpid for only part of the day (daily torpor).

Tests at different temperatures

A joint study conducted by Vetmeduni and the University of New England (Armidale, New South Wales, Australia) recently investigated this concept. The researchers tested how long-term survival on stored body fat – crucial for overcoming adverse periods – is related to the pattern of torpor.

The researchers investigated the pattern of torpor expressed by the eastern pygmy possum (Cercartetus nanus), a small mouse-sized marsupial, under different ambient temperatures, with 7 °C being typical of hibernation and 15 °C and 22 °C typical of daily torpor.

Pronounced differences in torpor patterns and survival times …

The pygmy possums expressed torpor at all temperatures and survived without food for an average of 310 days at 7 °C, 195 days at 15 °C and 127 days at 22 °C. At 7 °C and 15 °C, the duration of reduced body temperature (torpor bout duration, TBD) increased from < 1–3 to 5–16 days over two months; at 22 °C, TBD remained at less than 1 to about 2 days. At all temperatures, daily energy use was substantially lower and TBD and survival times much longer (3 to 12 months) than in daily heterotherms (around 10 days).

… indicate different ecological purposes

The study’s final author, Thomas Ruf from the Research Institute of Wildlife Ecology at Vetmeduni, concludes: “Such pronounced differences in torpor patterns and survival times even under similar thermal conditions provide strong support for the concept that torpor in hibernators and daily heterotherms are physiologically distinct and have evolved for different ecological purposes.”

The article “Long‑term survival, temperature, and torpor patterns” by Fritz Geiser and Thomas Ruf was published in Scientific Reports.

Scientific Article

2023-05-31

Niacin, formerly also known as vitamin B3, is involved in metabolism in mammals, has an antioxidant effect and is important for the regeneration of skin, muscles, nerves and DNA. A recent study at the University of Veterinary Medicine in Vienna investigated how a deficiency of niacin in brown hares affects reproductive performance: Reproductive performance does not take a hit, but there are clear negative effects on the body weight of the young hares.

Large areas of maize in agricultural landscapes are associated with reduced reproductive performance of females and impaired population development of free-living brown hares (Lepus europaeus). As part of an experimental study, a research team from the Vetmeduni therefore investigated captive brown hares to determine whether these effects were due to an undersupply of niacin from a maize-heavy diet. 

Lower body weight with a low-niacin diet

In the study, adult female hares were repeatedly mated. They were fed either a low-niacin pellet consisting mainly of corn plant parts or the same pellet enriched with niacin to meet physiological requirements.

The researchers measured the effects of the experimental feeding on female weight, reproductive performance, growth and survival of the young bunnies. "The body weight of females fed a niacin-rich diet was significantly higher and their young gained weight significantly faster," said study first author Aldin Selimovic of the Vetmeduni's Research Institute of Wildlife Ecology (FIWI).

No significant difference in reproductive success

However, the researchers found no significant difference between a niacin-deficient and a niacin-enriched diet in terms of the reproductive performance of females and the survival rates of their offspring. "Our results show that even a niacin-deficient diet only slightly affects the reproductive success of female field hares, presumably due to sufficient conversion of tryptophan to niacin or an additional supply of niacin from microorganisms in the caecum," Selimovic says. "The effects we found on the weight development of young hares in our animal husbandry could be much stronger in the wild - where the young hares are exposed to wind, rain and cold - and could strongly influence the survival of the young hares," Selimovic adds.

Life-threatening niacin deficiency in humans

After the arrival of Christopher Columbus in America, corn was one of the first crops to be brought to Europe. Due to its high yields, it quickly spread around the world and became a staple food for many people. However, the form of nicotinic acid (niacytin) bound in it cannot be utilized by the human body. As a result of an unbalanced diet, the deficiency disease pellagra often occurred in the past, which can lead to death if left untreated.

The a rticle "The effect of dietary niacin deficiency on reproduction of European brown hares: An experimental study" by Aldin Selimovic, Mathilde L. Tissier, Gabrielle Stalder, Johanna Painer-Gigler, Anna Haw, Hanna Rauch, and Walter Arnold was publishe in „Frontiers in Ecology and Evolution“.

Scientific article

2023-05-25

Reference genomes are high-quality genome datasets that provide important information of value for the protection of endangered species. An international research team led by the University of Veterinary Medicine Vienna has now succeeded in sequencing an even higher quality genome for cheetahs. The newly acquired dataset represents a milestone that will significantly improve the knowledge and understanding of this threatened feline.

The cheetah is a vulnerable species at risk of extinction. To help make the right conservation decisions, genomic analyses are becoming an increasingly important tool. Several genomic analyses of the cheetah, based on so-called short-read sequences, have already been published. In-depth genomic analyses, however, such as analyses of mutational load and genetic health, require highly continuous reference genomes. These reference genomes can provide information about the fitness and inbreeding status of a threatened species and play a crucial role in the development of management measures in conservation.

Reference genomes answer key biological questions

As a reference genome was currently unavailable for the cheetah, the researchers sequenced and assembled a chromosome-level genome for this threatened species. “The new reference genome VMU_Ajub_asm_v1.0 reflects a major improvement compared to the previously available cheetah genomes. It is the first assembly based on so-called long reads of long sequences of DNA molecules, which enabled us to assign even difficult areas of the genome, especially repetitive regions, and to fill previously existing gaps. The improved continuity of the genome will enable a variety of genome analyses that were not previously possible,” explains the study’s first author, Sven Winter of the Research Institute of Wildlife Ecology (FIWI) at Vetmeduni.

According to the researchers, the new genome resource provides a solid foundation for answering key biological questions for understanding the process of natural selection and adaptation. The study’s final author, Pamela Burger from the Research Institute of Wildlife Ecology at Vetmeduni, explains: “Highly continuous annotated chromosome-scale genome assemblies are valuable references for evolutionary or conservation genome analyses and allow in-depth studies on structural variation or the diversity and function of certain genes such as immune response genes. Genome assemblies of non-model organisms of this quality are currently rare, however.”

Fastest land animal in the world threatened with extinction

The cheetah (Acinonyx jubatus) is a large cat known as the fastest land animal, capable of speeds of up to 105 km/h. Historically, the cheetah could be found in open grasslands across Africa, the Arabian Peninsula and southwestern Asia. At present, it inhabits only a fraction of its former range, resulting in small and fragmented populations. The cheetah as a species is currently considered “vulnerable” on the International Union for Conservation of Nature (IUCN) Red List of threatened species, with two subspecies, A. j. venaticus (Iran) and A. j. hecki (northwest Africa), listed as “critically endangered”.
 

The article “A chromosome-scale high-contiguity genome assembly of the cheetah (Acinonyx jubatus)” by Sven Winter, René Meißner, Carola Greve, Alexander Ben Hamadou, Petr Horin, Stefan Prost and Pamela A. Burger was published in Journal of Heredity.

Scientific article

2023-05-16