Chronic cold exposure causes left ventricular hypertrophy that appears to be physiological.

Exposure to winter cold causes an increase in energy demands to meet the challenge of thermoregulation. In small rodents, this increase in cardiac output leads to a profound cardiac hypertrophy, 2-3 times that typically seen with exercise training. The nature of this hypertrophy and its relevance to winter mortality remains unclear.

Early life exposure to high temperature enhances locomotor performance without alteration in thermal ecology in different populations of Thoropa taophora tadpoles (Anura, Cycloramphidae).

Understanding the intricate relationship between temperature and physiological processes in ectotherm vertebrates is crucial for predicting how these animals respond to environmental changes, including those associated with climate change. This is particularly relevant for the anurans, given their limited capacity for thermoregulation, particularly in larval stages. Herein, we investigated the capacity for thermal acclimatization in Thoropa taophora tadpoles, an endemic species in the Atlantic rainforest of Southeast Brazil, inhabiting distinct thermal environments.

Manipulation of photoperiod induces fat storage, but not fat mobilization in the migratory songbird, Dumetella carolinensis (Gray Catbird).

The annual cycle of migratory birds requires significant phenotypic remodeling. We sought to induce the migratory phenotype in Gray Catbirds by exposing them to a short-day light cycle. While adipose storage was stimulated, exceeding that typically seen in wild birds, other aspects of the migratory phenotype were unchanged.

Contrasting Torpor Use by Reproductive Male Common Noctule Bats in the Laboratory and in the Field.

Metabolic processes of animals are often studied in controlled laboratory settings. However, these laboratory settings often do not reflect the animals' natural environment. Thus, results of metabolic measurements from laboratory studies must be cautiously applied to free-ranging animals.

Flexible energy-saving strategies in female temperate-zone bats.

Torpor is characterized by an extreme reduction in metabolism and a common energy-saving strategy of heterothermic animals. Torpor is often associated with cold temperatures, but in the last decades, more diverse and flexible forms of torpor have been described. For example, tropical bat species maintain a low metabolism and heart rate at high ambient and body temperatures.

Cardiovascular contributions and energetic costs of thermoregulation in ectothermic vertebrates.

Ectothermic vertebrates use a suite of physiological and behavioral mechanisms to thermoregulate, which result in various thermoregulatory strategies from thermoconformity to thermoregulation. Here, we present a novel synthesis of theoretical and empirical methods to determine cardiovascular contributions to heat transfer in free-living ectothermic vertebrates. We start by identifying the fundamental components of heat transfer and the cardiovascular mechanisms for physiological modulation of heat exchange, and then integrate these components into a single, integrative framework: the cardiovascular heat exchange framework (CHEF).

Metabolic rate in common shrews is unaffected by temperature, leading to lower energetic costs through seasonal size reduction.

Small endothermic mammals have high metabolisms, particularly at cold temperatures. In the light of this, some species have evolved a seemingly illogical strategy: they reduce the size of the brain and several organs to become even smaller in winter. To test how this morphological strategy affects energy consumption across seasonally shifting ambient temperatures, we measured oxygen consumption and behaviour in the three seasonal phenotypes of the common shrew (), which differ in size by about 20%.

Daily energy expenditure in white storks is lower after fledging than in the nest.

Many juvenile birds turn into long-distance migrants within weeks of fledging. This transition involves upheavals in their energy management as major changes in growth and activity occur. Understanding such ontogenetic transitions in energy allocation has been difficult because collecting continuous data on energy costs in wild developing birds was previously largely impossible.

Differential plasticity of membrane fatty acids in northern and southern populations of the eastern newt (Notophthalmus viridescens).

Seasonal changes in membrane composition and metabolic activity allow many temperate ectotherms to contend with changes in body temperature, but few studies have investigated whether the plasticity of these traits has diverged within a single species. Therefore, we studied the effects of thermal acclimation on the membrane fatty acid composition and the activities of cytochrome c oxidase (CCO) and citrate synthase (CS) in the skeletal muscle and liver of eastern newts from Maine and Florida. Newts were acclimated to either 6 °C or 28 °C for 12 weeks prior to experiments.

Conserved transcriptional activity and ligand responsiveness of avian PPARs: Potential role in regulating lipid metabolism in mirgratory birds.

Migratory birds undergo metabolic remodeling in tissues, including increased lipid storage in white adipose and fatty acid uptake and oxidation in skeletal muscle, to optimize energy substrate availability and utilization in preparation for long-distance flight. Different tissues undergo gene expression changes in keeping with their specialized functions and driven by tissue specific transcriptional pathways. Peroxisome proliferator-activated receptors (PPARs) are lipid-activated nuclear receptors that regulate metabolic pathways involved in lipid and glucose utilization or storage in mammals.

Activity and movement of free-living box turtles are largely independent of ambient and thermal conditions.

Background: Ectotherms are assumed to be strongly influenced by the surrounding ambient and environmental conditions for daily activity and movement. As such, ecological and physiological factors contribute to stimuli influencing navigation, extent of movement, and therefore habitat use. Our study focused on the intensity of activity (from acceleration data) and extent of movement (from GPS and thread trailing data) of Eastern box turtles () in a fragmented landscape near their northern population limit.

Thermoregulatory performance and habitat selection of the eastern box turtle ().

Environmental conditions may affect individual physiological processes that influence short-term performance and ultimately growth, survival and reproduction. As such, habitats selected by animals must provide suitable and adequate resources. Ectothermic species are highly dependent on climatic conditions and ambient temperatures that dictate body temperature regulation and in turn physiological processes.

Intramuscular triglyceride content precedes impaired glucose metabolism without evidence for mitochondrial dysfunction during early development of a diabetic phenotype.

The incidence of type 2 diabetes is highly correlated with obesity; however, there is a lack of research elucidating the temporal progression. Transgenic FVB/N UCP-dta mice, which develop a diabetic phenotype, and their nontransgenic littermates were fed either a high-fat or normal-chow diet and were studied at 6, 9, 12, 15, 18, 21, and 24 weeks of age to test the hypothesis that increased lipid accumulation in skeletal muscle causes mitochondrial dysfunction, leading to the development of insulin resistance. Body composition, intramuscular triglyceride (IMTG) content, glucose metabolism, and mitochondrial function were measured to determine if IMTG drove mitochondrial dysfunction, leading to the development of type 2 diabetes.

Annual life-stage regulation of lipid metabolism and storage and association with PPARs in a migrant species: the gray catbird (Dumetella carolinensis).

The annual cycle of a migrating bird involves metabolically distinct stages of substantial fatty acid storage and periods of increased fatty acid mobilization and utilization, and thus requires a great deal of phenotypic flexibility. Specific mechanisms directing stage transitions of lipid metabolism in migrants are largely unknown. This study characterized the role of the PPARs (peroxisome proliferator-activated receptors) in regulating migratory adiposity of the gray catbird (Dumetella carolinensis).

Thermal Acclimatization in Overwintering Tadpoles of the Green Frog, Lithobates clamitans (Latreille, 1801).

Seasonal acclimatization permits organisms to maintain function in the face of environmental change. Tadpoles of the green frog (Lithobates clamitans) overwinter as tadpoles in much of their range. Because they are active in winter, we hypothesized that green frog tadpoles would display acclimatization of metabolic and locomotor function.

Compensatory responses of the insulin signaling pathway restore muscle glucose uptake following long-term denervation.

We investigated the role of muscle activity in maintaining normal glucose homeostasis via transection of the sciatic nerve, an extreme model of disuse atrophy. Mice were killed 3, 10, 28, or 56 days after transection or sham surgery. There was no difference in muscle weight between sham and transected limbs at 3 days post surgery, but it was significantly lower following transection at the other three time points.

The thermal plasticity of locomotor performance has diverged between northern and southern populations of the eastern newt (Notophthalmus viridescens).

Many temperate ectotherms undergo thermal acclimation to remain functional over a wide range of body temperatures, but few studies have investigated whether populations of a single species have evolved differences in the thermal plasticity of locomotor performance. Therefore, we asked whether the thermal plasticity of locomotor performance has diverged between northern and southern populations of eastern newts (Notophthalmus viridescens). We acclimated eastern newts from Florida and Maine to cold (6 °C) or warm (28 °C) conditions for 12 weeks.

Does the thermal plasticity of metabolic enzymes underlie thermal compensation of locomotor performance in the eastern newt (Notophthalmus viridescens)?

Eastern newts (Notophthalmus viridescens) upregulate the metabolic capacity of skeletal muscle in winter to compensate for thermodynamic effects on metabolism. However, whether this compensation facilitates locomotor performance at low temperature is unknown. Therefore, our aim was to determine if thermal acclimation of metabolic enzymes in muscle benefits locomotion.

Animal galloping and human hopping: an energetics and biomechanics laboratory exercise.

This laboratory exercise demonstrates fundamental principles of mammalian locomotion. It provides opportunities to interrogate aspects of locomotion from biomechanics to energetics to body size scaling. It has the added benefit of having results with robust signal to noise so that students will have success even if not "meticulous" in attention to detail.

How animals move: comparative lessons on animal locomotion.

Comparative physiology often provides unique insights in animal structure and function. It is specifically through this lens that we discuss the fundamental properties of skeletal muscle and animal locomotion, incorporating variation in body size and evolved difference among species. For example, muscle frequencies in vivo are highly constrained by body size, which apparently tunes muscle use to maximize recovery of elastic recoil potential energy.

Does low daily energy expenditure drive low metabolic capacity in the tropical robin, Turdus grayi?

Temperate and tropical birds possess divergent life history strategies. Physiological parameters including energy metabolism correlate with the life history such that tropical species with a slower 'pace of life' have lower resting and maximal metabolic rates than temperate congeners. To better understand the physiological mechanisms underlying these differences, we investigated the relationship of metabolic capacity, muscle oxidative capacity and activity patterns to variation in life history patterns in American robins (Turdus migratorius), while resident in central North America and Clay-colored robins (Turdus grayi) resident in Panama.

Acclimatization of seasonal energetics in northern cardinals (Cardinalis cardinalis) through plasticity of metabolic rates and ceilings.

Northern cardinals (Cardinalis cardinalis) are faced with energetically expensive seasonal challenges that must be met to ensure survival, including thermoregulation in winter and reproductive activities in summer. Contrary to predictions of life history theory that suggest breeding metabolic rate should be the apex of energetic effort, winter metabolism exceeds that during breeding in several temperate resident bird species. By examining whole-animal, tissue and cellular function, we ask whether seasonal acclimatization is accomplished by coordinated phenotypic plasticity of metabolic systems.

Impaired contractile function and calcium handling in hearts of cardiac-specific calcineurin b1-deficient mice.

To define the necessity of calcineurin (Cn) signaling for cardiac maturation and function, the postnatal phenotype of mice with cardiac-specific targeted ablation of the Cn B1 regulatory subunit (Ppp3r1) gene (csCnb1(-/-) mice) was characterized. csCnb1(-/-) mice develop a lethal cardiomyopathy, characterized by impaired postnatal growth of the heart and combined systolic and diastolic relaxation abnormalities, despite a lack of structural derangements. Notably, the csCnb1(-/-) hearts did not exhibit diastolic dilatation, despite the severe functional phenotype.

Transcriptional coactivators PGC-1alpha and PGC-lbeta control overlapping programs required for perinatal maturation of the heart.

Oxidative tissues such as heart undergo a dramatic perinatal mitochondrial biogenesis to meet the high-energy demands after birth. PPARgamma coactivator-1 (PGC-1) alpha and beta have been implicated in the transcriptional control of cellular energy metabolism. Mice with combined deficiency of PGC-1alpha and PGC-1beta (PGC-1alphabeta(-/-) mice) were generated to investigate the convergence of their functions in vivo.