Gene expression changes in ducklings exposed in ovo to emerging and legacy per-/poly-fluoroalkyl substances.

This study investigated the effects of two emerging PFAS compounds, perfluorododecane sulfonic acid (PFDoDS) and perfluoro-4-ethylcyclohexane sulfonic acid (PFECHS), alongside legacy perfluorooctanesulfonic acid (PFOS), on gene expression in the liver, heart, and bursa of Fabricius from mallard ducklings (Anas platyrhynchos) exposed in ovo, simulating maternal transfer to the egg. These PFAS compounds were selected based on their detection in a declining sea duck species and concerns over their endocrine disruption potential. Farmed mallard eggs were injected with 80 ng/g of PFDoDS, PFECHS, or PFOS, reflecting concentrations at the upper end of those reported in wild bird eggs.

Physiological mechanisms of rapid and long-term thermal acclimation in a fish.

To better cope with changing water temperatures, most aquatic ectotherms undergo physiological acclimation which often alters their thermal tolerance. The timeframe and relative contribution of various underlying mechanisms remain unclear, but are crucial to understand for predictions of climate change impacts. We investigated three candidate mechanisms involved in thermal acclimation in fish: heat shock protein expression (specifically HSP70), mitochondrial density (citrate synthase [CS] expression), and membrane fluidity (via spectroscopic fluorescence polarization).

A Comparison of the Mitochondrial Performance between Migratory and Sedentary Mimid Thrushes.

Birds exhibit a variety of migration strategies. Because sustained flapping flight requires the production of elevated levels of energy compared to typical daily activities, migratory birds are well-documented to have several physiological adaptations to support the energy demands of migration. However, even though mitochondria are the source of ATP that powers flight, the respiratory performance of the mitochondria is almost unstudied in the context of migration.

Subclinical thiamine deficiency results in failed reproduction in Arctic foxes.

Thiamine deficiency can result in life-threatening physiological and neurological complications. While a thiamine-deficient diet may result in the onset of such symptoms, the presence of thiaminase - an enzyme that breaks down thiamine - is very often the cause. In such instances, thiaminase counteracts the bioavailability and uptake of thiamine, even when food-thiamine levels are adequate.

The persistent effects of corticosterone administration during lactation on the physiology of maternal and offspring mitochondria.

Reproduction and environmental stressors are generally thought to be associated with a cost to the individual experiencing them, but the physiological mechanisms mediating costs of reproduction and maternal effects remain poorly understood. Studies examining the effects of environmental stressors on a female's physiological state and body condition during reproduction, as well as the physiological condition of offspring, have yielded equivocal results. Mitochondrial physiology and oxidative stress have been implicated as important mediators of life-history trade-offs.

Naked mole-rat and Damaraland mole-rat exhibit lower respiration in mitochondria, cellular and organismal levels.

Naked mole-rats (NMR) and Damaraland mole-rats (DMR) exhibit extraordinary longevity for their body size, high tolerance to hypoxia and oxidative stress and high reproductive output; these collectively defy the concept that life-history traits should be negatively correlated. However, when life-history traits share similar underlying physiological mechanisms, these may be positively associated with each other. We propose that one such potential common mechanism might be the bioenergetic properties of mole-rats.

Reduced Mitochondrial Respiration in Hybrid Asexual Lizards.

AbstractThe scarcity of asexual reproduction in vertebrates alludes to an inherent cost. Several groups of asexual vertebrates exhibit lower endurance capacity (a trait predominantly sourced by mitochondrial respiration) compared with congeneric sexual species. Here we measure endurance capacity in five species of lizards and examine mitochondrial respiration between sexual and asexual species using mitochondrial respirometry.

Mitochondrial Bioenergetics of Extramammary Tissues in Lactating Dairy Cattle.

Lactation is physiologically demanding, requiring increased nutrient and energy use. Mammary and extramammary tissues undergo metabolic changes for lactation. Although it has long been recognized that mitochondria play a critical role in lactation, the mitochondrial adaptations for milk synthesis in supporting tissues, such as liver and skeletal muscle are relatively understudied.

Development of a Mobile Mitochondrial Physiology Laboratory for Measuring Mitochondrial Energetics in the Field.

Mitochondrial energetics is a central theme in animal biochemistry and physiology, with researchers using mitochondrial respiration as a metric to investigate metabolic capability. To obtain the measures of mitochondrial respiration, fresh biological samples must be used, and the entire laboratory procedure must be completed within approximately 2 h. Furthermore, multiple pieces of specialized equipment are required to perform these laboratory assays.

Revisiting the question of nucleated versus enucleated erythrocytes in birds and mammals.

Erythrocyte enucleation is thought to have evolved in mammals to support their energetic cost of high metabolic activities. However, birds face similar selection pressure yet possess nucleated erythrocytes. Current hypotheses on the mammalian erythrocyte enucleation claim that the absence of cell organelles allows erythrocytes to ) pack more hemoglobin into the cells to increase oxygen carrying capacity and ) decrease erythrocyte size for increased surface area-to-volume ratio, and improved ability to traverse small capillaries.

Sex-specific energy management strategies in response to training for increased foraging effort prior to reproduction in captive zebra finches.

Free-living animals often engage in behaviour that involves high rates of workload and results in high daily energy expenditure (DEE), such as reproduction. However, the evidence for elevated DEE accompanying reproduction remains equivocal. In fact, many studies have found no difference in DEE between reproducing and non-reproducing females.

Physiological adjustments to high foraging effort negatively affect fecundity but not final reproductive output in captive zebra finches.

Foraging at elevated rates to provision offspring is thought to be an energetically costly activity and it has been suggested that there are physiological costs associated with the high workload involved. However, for the most part, evidence for costs of increased foraging and/or reproductive effort is weak. Furthermore, despite some experimental evidence demonstrating negative effects of increased foraging and parental effort, the physiological mechanisms underlying costs associated with high workload remain poorly understood.

Evaluating endoplasmic reticulum stress and unfolded protein response through the lens of ecology and evolution.

Considerable progress has been made in understanding the physiological basis for variation in the life-history patterns of animals, particularly with regard to the roles of oxidative stress and hormonal regulation. However, an underappreciated and understudied area that could play a role in mediating inter- and intraspecific variation of life history is endoplasmic reticulum (ER) stress, and the resulting unfolded protein response (UPR ). ER stress response and the UPR maintain proteostasis in cells by reducing the intracellular load of secretory proteins and enhancing protein folding capacity or initiating apoptosis in cells that cannot recover.

Prior reproduction alters how mitochondria respond to an oxidative event.

An animal's pace of life is mediated by the physiological demands and stressors it experiences (e.g. reproduction) and one likely mechanism that underlies these effects is oxidative stress.

Haematological traits co-vary with migratory status, altitude and energy expenditure: a phylogenetic, comparative analysis.

Aerobic capacity is assumed to be a main predictor of workload ability and haematocrit (Hct) and haemoglobin (Hb) have been suggested as key determinants of aerobic performance. Intraspecific studies have reported increases in Hct and Hb in response to increased workload. Furthermore, Hct and Hb vary markedly among individuals and throughout the annual cycle in free-living birds and it has been suggested that this variation reflects adaptive modulation of these traits to meet seasonal changes in energy demands.

Effects of experimental manipulation of hematocrit on avian flight performance in high- and low-altitude conditions.

Despite widely held assumptions that hematocrit (Hct) is a key determinant of aerobic capacity and exercise performance, this relationship has not often been tested rigorously in birds and results to date are mixed. Migration in birds involves high-intensity exercise for long durations at various altitudes. Therefore, it provides a good model system to examine the effect of Hct on flight performance and physiological responses of exercise at high altitude.

Experimental Increases in Foraging Costs Affect Pectoralis Muscle Mass and Myostatin Expression in Female, but Not Male, Zebra Finches (Taeniopygia guttata).

Skeletal muscle remodeling is an important component of phenotypic flexibility in birds and impacts organismal metabolism and performance, which could potentially influence fitness. One regulator of skeletal muscle remodeling is myostatin, an autocrine/paracrine muscle growth inhibitor that may be down-regulated under conditions promoting heavier muscle masses. In this study, we employed protocols requiring hovering while foraging to increase foraging costs and modify phenotypes of zebra finches (Taeniopygia guttata).

Physiological effects of increased foraging effort in a small passerine.

Foraging to obtain food, either for self-maintenance or at presumably elevated rates to provide for offspring, is thought to be an energetically demanding activity but one that is essential for fitness (higher reproductive success and survival). Nevertheless, the physiological mechanisms that allow some individuals to support higher foraging performance, and the mechanisms underlying costs of high workload, remain poorly understood. We experimentally manipulated foraging behaviour in zebra finches () using the technique described by Koetsier and Verhulst (2011) Birds in the 'high foraging effort' (HF) group had to obtain food either while flying/hovering or by making repeated hops or jumps from the ground up to the feeder, behaviour typical of the extremely energetically expensive foraging mode observed in many free-living small passerines.

The Physiology of Exercise in Free-Living Vertebrates: What Can We Learn from Current Model Systems?

Many behaviors crucial for survival and reproductive success in free-living animals, including migration, foraging, and escaping from predators, involve elevated levels of physical activity. However, although there has been considerable interest in the physiological and biomechanical mechanisms that underpin individual variation in exercise performance, to date, much work on the physiology of exercise has been conducted in laboratory settings that are often quite removed from the animal's ecology. Here we review current, laboratory-based model systems for exercise (wind or swim tunnels for migration studies in birds and fishes, manipulation of exercise associated with non-migratory activity in birds, locomotion in lizards, and wheel running in rodents) to identify common physiological markers of individual variation in exercise capacity and/or costs of increased activity.

Sex steroid profiles in zebra finches: Effects of reproductive state and domestication.

The zebra finch is a common model organism in neuroscience, endocrinology, and ethology. Zebra finches are generally considered opportunistic breeders, but the extent of their opportunism depends on the predictability of their habitat. This plasticity in the timing of breeding raises the question of how domestication, a process that increases environmental predictability, has affected their reproductive physiology.

Sex steroid profiles and pair-maintenance behavior of captive wild-caught zebra finches (Taeniopygia guttata).

Here, we studied the life-long monogamous zebra finch, to examine the relationship between circulating sex steroid profiles and pair-maintenance behavior in pairs of wild-caught zebra finches (paired in the laboratory for >1 month). We used liquid chromatography-tandem mass spectrometry to examine a total of eight androgens and progestins [pregnenolone, progesterone, dehydroepiandrosterone (DHEA), androstenediol, pregnan-3,17-diol-20-one, androsterone, androstanediol, and testosterone]. In the plasma, only pregnenolone, progesterone, DHEA, and testosterone were above the limit of quantification.

Acute and chronic effects of an aromatase inhibitor on pair-maintenance behavior of water-restricted zebra finch pairs.

Zebra finches are highly social songbirds that maintain life-long monogamous pair-bonds. They rely heavily upon these pair-bonds to survive their ever-changing and unpredictable habitat in the Australian desert. These pair-bonds are maintained via a large repertoire of affiliative behaviors that for most of an individual's life are predominately associated with pair maintenance.