Basal metabolic rate shapes the development and progression of hepatocellular carcinoma.

Background: Among several cancer risk factors, the variation in basal metabolism rate (BMR), which constitutes up to 70% of total energy expenditures in humans, may be causally linked with neoplasm development. As BMR reflects the mass of metabolically active organs, being the function of cell size and/or cell number, it may serve as a critical metabolic proxy of cancer susceptibility in the context of cell growth and cell size.

Methods: We examined the progression and rate of development of chemically induced hepatocellular carcinoma, using lines of mice divergently selected for high or low BMR and differing with respect to both the size of metabolically active organs and their cellular architecture.

Lactation at hot temperature: a test of heat dissipation limitation in mice divergently selected for basal metabolic rate.

The HDL (heat dissipation limitation) hypothesis posits that mammalian energy budgets (SuSMR, sustained metabolic rate) are limited by the ability to dissipate metabolic heat. The HDL hypothesis has been tested in lactating mice but rarely systematically differs in SuSMR. Here, we used lines of laboratory mice divergently selected for basal metabolic rate (BMR) and effectively co-selected for SuSMR.

Evolution of cellular architecture and function of the hippocampus: insights from the artificial selection experiment.

Inter-specifically, mammalian species with larger brains built of numerous neurons have higher cognitive abilities (CA) but at the expense of higher metabolic costs. It is unclear, however, how this pattern emerged since evolutionary mechanisms act intra-specifically, not inter-specifically. Here, we tested the existence of the above pattern at the species level in the hippocampus-the brain structure underlying CA.

Divergent selection for basal metabolic rate in mice affects the abundance of UCP1 protein: implications for translational studies.

Low basal metabolic rate (BMR) is a risk factor for obesity, whereas elevation of non-shivering thermogenesis (NST) is a promising means to combat obesity. Because heat generated by NST covers thermogenic needs not fulfilled by BMR, one can expect the presence of a negative relationship between both parameters. Understanding of the mechanisms underlying this relationship is therefore important for interpretation of the results of translational experiments and the development of anti-obesity treatments.

Reproduction results in parallel changes of oxidative stress and immunocompetence in a wild long-living mammal-edible dormouse .

Oxidative stress (OS) and impaired immune function (IF) have been proposed as key physiological costs of reproduction. The relationship between OS and IF remains unresolved, particularly in long-living iteroparous species. We studied physiological markers of maintenance (OS, IF markers) in lactating, post-lactating and non-lactating females of edible dormice-a long-living rodent.

Local variation in brain temperature explains gender-specificity of working memory performance.

Introduction: Exploring gender differences in cognitive abilities offers vital insights into human brain functioning.

Methods: Our study utilized advanced techniques like magnetic resonance thermometry, standard working memory n-back tasks, and functional MRI to investigate if gender-based variations in brain temperature correlate with distinct neuronal responses and working memory capabilities.

Results: We observed a significant decrease in average brain temperature in males during working memory tasks, a phenomenon not seen in females.

Differences in the range of thermoneutral zone between mouse strains: potential effects on translational research.

Laboratory mice are commonly used for studies emulating human metabolism. To render human energetics, their ratio of daily (DEE) to basal (BMR) energy expenditure of 1.7-1.

Decay rates of arboreal and terrestrial nests of Eastern chimpanzees (Pan troglodytes schweinfurthii) in the Bugoma Central Forest Reserve, Uganda: Implications for population size estimates.

Chimpanzees were once thought to sleep primarily in the trees, but recent studies indicate that some populations also construct terrestrial night nests. This behavior has relevance not only to understanding the behavioral diversity of Pan troglodytes, but also to the conservation of the species, given that nest encounter rates are often used to estimate great ape population densities. A proper estimate of decay rates for ground nests is necessary for converting the encounter rate of nests to the density of weaned chimpanzees.

Factors affecting nest height and ground nesting behaviour in Eastern chimpanzees (Pan troglodytes schweinfurthii) of the northern Democratic Republic of the Congo.

In order to achieve a better understanding of the factors that might have led our hominin ancestors to transition to a more terrestrial niche, including sleeping on the ground, we have conducted a study on the ground nesting behavior of chimpanzees (Pan troglodytes). Chimpanzees, like all other species of great apes, build nests in which to sleep each night, but little is known about regional differences in their nesting habits. Previously, nesting on the ground was considered typical of gorillas, but rare in most populations of chimpanzees.

Mice selected for a high basal metabolic rate evolved larger guts but not more efficient mitochondria.

Intra-specific variation in both the basal metabolic rate (BMR) and mitochondrial efficiency (the amount of ATP produced per unit of oxygen consumed) has profound evolutionary and ecological consequences. However, the functional mechanisms responsible for this variation are not fully understood. Mitochondrial efficiency is negatively correlated with BMR at the interspecific level but it is positively correlated with performance capacity at the intra-specific level.

Brain size, gut size and cognitive abilities: the energy trade-offs tested in artificial selection experiment.

The enlarged brains of homeotherms bring behavioural advantages, but also incur high energy expenditures. The 'expensive brain' (EB) hypothesis posits that the energetic costs of the enlarged brain and the resulting increased cognitive abilities (CA) were met by either increased energy turnover or reduced allocation to other expensive organs, such as the gut. We tested the EB hypothesis by analysing correlated responses to selection in an experimental evolution model system, which comprises line types of laboratory mice selected for high or low basal metabolic rate (BMR), maximum (VO) metabolic rates and random-bred (unselected) lines.

Plant-herbivore interactions: Combined effect of groundwater level, root vole grazing, and sedge silicification.

Accumulation of silica (Si) by plants can be driven by (1) herbivory pressure (and therefore plant-herbivore interactions), (2) geohydrological cycles, or (3) a combination of (1) and (2), with (1-3) possibly affecting Si concentration with a 1-year delay.To identify the relative significance of (1-3), we analyzed the concentration of Si in fibrous tussock sedge (), the population density of the root vole (), and the groundwater level, over 11 years.The largest influence of autumn Si concentration in leaves (Si) was on the level of the current-year groundwater table, which was positive and accounted for 13.

Larger guts and faster growth in mice selected for high basal metabolic rate.

Postnatal growth in birds and mammals is the time of highest vulnerability and relatively high energy demands and therefore shapes the organisms' future outcomes. Several different factors might impose limitations on growth in juveniles, one of them being the efficiency of the digestive process and size of the gastrointestinal tract. We tested the gut size-growth rate relationship using a unique experimental model-mice from a selection experiment designed to produce two lines with divergent levels of basal metabolic rate (BMR): the high BMR (H-BMR) and low BMR (L-BMR) line types.

Significance of variation in basal metabolic rate in laboratory mice for translational experiments.

The basal metabolic rate (BMR) accounts for 60-70% of the daily energy expenditure (DEE) in sedentary humans and at least 50% of the DEE in laboratory mice in the thermoneutral zone. Surprisingly, however, the significance of the variation in the BMR is largely overlooked in translational research using such indices as physical activity level (PAL), i.e.

Low basal metabolic rate as a risk factor for development of insulin resistance and type 2 diabetes.

Introduction: Identification of physiological factors influencing susceptibility to insulin resistance and type 2 diabetes (T2D) remains an important challenge for biology and medicine. Numerous studies reported energy expenditures as one of those components directly linked to T2D, with noticeable increase of basal metabolic rate (BMR) associated with the progression of insulin resistance. Conversely, the putative link between genetic, rather than phenotypic, determination of BMR and predisposition to development of T2D remains little studied.

Coevolution of body size and metabolic rate in vertebrates: a life-history perspective.

Despite many decades of research, the allometric scaling of metabolic rates (MRs) remains poorly understood. Here, we argue that scaling exponents of these allometries do not themselves mirror one universal law of nature but instead statistically approximate the non-linearity of the relationship between MR and body mass. This 'statistical' view must be replaced with the life-history perspective that 'allows' organisms to evolve myriad different life strategies with distinct physiological features.

Functional and structural changes in aorta of mice divergently selected for basal metabolic rate.

Cardiovascular diseases (CVD) are one of the most common causes of mortality likely genetically linked to the variation in basal metabolic rate (BMR). A robust test of the significance of such association may be provided by artificial selection experiments on animals selected for diversification of BMR. Here we asked whether genetically determined differences in BMR correlate with anatomical shift in endothelium structure and if so, the relaxation and contraction responses of the aorta in mice from two lines of Swiss-Webster laboratory mice (Mus musculus) divergently selected for high or low BMR (HBMR and LBMR lines, respectively).

Not that hot after all: no limits to heat dissipation in lactating mice selected for high or low BMR.

Heat dissipation has been suggested as a limit to sustained metabolic effort, e.g. during lactation, when overheating is a possible risk.

Long-Term Trait Consistency in Mice Selected for Swim-Induced High Aerobic Capacity.

The majority of studies show that metabolic rates are usually repeatable at the individual level, although their repeatabilities tend to decline with time and to be strongly affected by physiological changes. Changes in individual repeatabilities may therefore affect putative differences between experimental groups or populations. This problem is particularly relevant to artificial selection experiments that apply the selection protocol at early life stages, running the risk of a poor correlation of the trait with itself throughout the life cycle of individuals.

The nexus of hair corticosterone level, immunocompetence, metabolic rates and overwinter survival in the root vole, Microtus oeconomus.

Although corticosterone (CORT) regulates many physiological mechanisms, the associations between CORT levels, immunocompetence, energy expenditures and overwinter survival have not been examined. Here, we studied individual variation in CORT level extracted from hair, immunocompetence quantified as the neutrophil-to-lymphocyte (N/L) ratio, total white blood cells (WBC) and natural antibody levels (NAbs), along with the resting (RMR) and peak metabolic rates (PMR) and mortality during three consecutive winter seasons in a natural population of the root vole, Microtus oeconomus. In early winter, hair CORT level was strongly positively associated with body mass and inversely related to voles' ability to survive.

Selection for high aerobic capacity has no protective effect against obesity in laboratory mice.

Aerobic capacity (VO measured during intensive physical exercise) both trained and intrinsic (i.e. genetically determined) has recently been deemed a good predictor of cardiometabolic risks.

Metabolic risk factors in mice divergently selected for BMR fed high fat and high carb diets.

Factors affecting contribution of spontaneous physical activity (SPA; activity associated with everyday tasks) to energy balance of humans are not well understood, as it is not clear whether low activity is related to dietary habits, precedes obesity or is a result of thereof. In particular, human studies on SPA and basal metabolic rates (BMR, accounting for >50% of human energy budget) and their associations with diet composition, metabolic thrift and obesity are equivocal. To clarify these ambiguities we used a unique animal model-mice selected for divergent BMR rates (the H-BMR and L-BMR line type) presenting a 50% between-line type difference in the primary selected trait.

Effect of calorie restriction on spontaneous physical activity and body mass in mice divergently selected for basal metabolic rate (BMR).

Spontaneous physical activity (SPA) represents an important component of daily energy expenditures in animals and humans. Intra-specific variation in SPA may be related to the susceptibility to metabolic disease or obesity. In particular, reduced SPA under conditions of limited food availability may conserve energy and prevent loss of body and fat mass ('thrifty genotype hypothesis').

Heat dissipation does not suppress an immune response in laboratory mice divergently selected for basal metabolic rate (BMR).

The capacity for heat dissipation is considered to be one of the most important constraints on rates of energy expenditure in mammals. To date, the significance of this constraint has been tested exclusively under peak metabolic demands, such as during lactation. Here, we used a different set of metabolic stressors, which do not induce maximum energy expenditures and yet are likely to expose the potential constraining effect of heat dissipation.