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The aim of this study was to investigate whether the actively wintering Palearctic sable Martes zibellina has evolved physiological adaptations to tolerate nutritional scarcity. Sixteen farm-bred male sables were divided into a fed control group and an experimental group fasted for 4 days. The rate of weight loss in the sable was similar to other medium-sized mustelids. Fasting led to hypoglycaemia and to a decreased lymphocyte percentage. The sable derived metabolic energy from both subcutaneous and intraabdominal white adipose tissues and the relative decrease in fat mass was the largest for the retroperitoneal and subcutaneous depots. Metabolic energy derived partly from body proteins indicated by the increased plasma levels of urea, uric acid and total essential amino acids. Triacylglycerols accumulated in the livers of the fasted sables and the increased plasma aminotransferase activities suggested hepatic dysfunction. The decreased plasma insulin concentrations and the elevated cortisol levels probably contributed to stimulated lipolysis and protein catabolism. Moreover, fasting increased the plasma ghrelin concentrations of the sables and down-regulated the thyroid activity.
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... It is necessary to determine how environmental conditions affect sables. Previous studies demonstrated that sable population in different climatic habitats differed in various characteristics [9], and much effort has been paid to sable morphology [4,10,11], behavior [12][13][14][15], geographic distribution [16][17][18], and habitat ecology [19,20]. Characteristics of intestinal microflora, such as energy metabolism, are essential for adapting to harsh environmental conditions [21]. ...
... An explanation for this situation is that Lactobacillus mainly process sugar type compounds rather than proteins and lipid [61], but there is less vegetarian resources in elevated habitat where wild sables tend to consume less carbohydrates. Mustonen [15] demonstrated that wild sables may suffer symptoms of hypoglycemia in cold and high-altitude regions where vegetative food sources are scarce, which to a certain extent provides support for our conclusions. Contrary to Lactobacillus, another dominant genus Pseudomonas, whose relative abundance increased with altitude, has been considered a crucial genus in sable gut with the ability to produce lipase [62]. ...
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In recent decades, wild sable (Carnivora Mustelidae Martes zibellina) habitats, which are often natural forests, have been squeezed by anthropogenic disturbances such as clear-cutting, tilling and grazing. Sables tend to live in sloped areas with relatively harsh conditions. Here, we determine effects of environmental factors on wild sable gut microbial communities between high and low altitude habitats using Illumina Miseq sequencing of bacterial 16S rRNA genes. Our results showed that despite wild sable gut microbial community diversity being resilient to many environmental factors, community composition was sensitive to altitude. Wild sable gut microbial communities were dominated by Firmicutes (relative abundance 38.23%), followed by Actinobacteria (30.29%), and Proteobacteria (28.15%). Altitude was negatively correlated with the abundance of Firmicutes, suggesting sable likely consume more vegetarian food in lower habitats where plant diversity, temperature and vegetation coverage were greater. In addition, our functional genes prediction and qPCR results demonstrated that energy/fat processing microorganisms and functional genes are enriched with increasing altitude, which likely enhanced metabolic functions and supported wild sables to survive in elevated habitats. Overall, our results improve the knowledge of the ecological impact of habitat change, providing insights into wild animal protection at the mountain area with hash climate conditions.
... Similarly, the polar bear is the largest extant bear to adapt to the cold Arctic regions, weighing 372 kg on average [32]. Interestingly, polar bears and seals have relatively thick subcutaneous fat, which accounts for more than 30 % of their body weights, much more than that of other wild carnivores [33][34][35]. It has been suggested that the thick layer of fat covering pinnipeds and polar bears is an adaptation to the cold. ...
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Background The range of body sizes in Carnivora is unparalleled in any other mammalian order—the heaviest species is 130,000 times heavier than the lightest and the longest species is 50 times longer than the shortest. However, the molecular mechanisms underlying these huge differences in body size have not been explored. Results Herein, we performed a comparative genomics analysis of 20 carnivores to explore the evolutionary basis of the order’s great variations in body size. Phylogenetic generalized least squares (PGLS) revealed that 337 genes were significantly related to both head body length and body mass; these genes were defined as body size associated genes (BSAGs). Fourteen positively-related BSAGs were found to be associated with obesity, and three of these were under rapid evolution in the extremely large carnivores, suggesting that these obesity-related BSAGs might have driven the body size expansion in carnivores. Interestingly, 100 BSAGs were statistically significantly enriched in cancer control in carnivores, and 15 of which were found to be under rapid evolution in extremely large carnivores. These results suggested that large carnivores might have evolved an effective mechanism to resist cancer, which could be regarded as molecular evidence to support Peto’s paradox. For small carnivores, we identified 15 rapidly evolving genes and found six genes with fixed amino acid changes that were reported to reduce body size. Conclusions This study brings new insights into the molecular mechanisms that drove the diversifying evolution of body size in carnivores, and provides new target genes for exploring the mysteries of body size evolution in mammals.
... Similarly, the polar bear is the largest extant bear to adapt to the cold Arctic regions, which are averagely weighed 372 kg [26]. Interestingly, polar bears and seals have relatively thick subcutaneous fat, which accounted for more than 30% of their body weight and were much higher than that of other wild carnivores [27][28][29]. It has been suggested that pinnipeds and polar bears are covered with a thick layer of fat to protect them from cold environment. ...
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