Orientia, Rickettsia, and the microbiome in rodent attached chiggers in North Carolina, USA.

Chiggers are larval mites that pose a significant health risk globally via the spread of scrub typhus. However, fundamental studies into the bacterial microbiome in North America have never been considered. In this investigation, chiggers were collected in the wild from two locally common rodent host species (i.

Developmental programming of sarcoplasmic reticulum function improves cardiac anoxia tolerance in turtles.

Oxygen deprivation during embryonic development can permanently remodel the vertebrate heart, often causing cardiovascular abnormalities in adulthood. While this phenomenon is mostly damaging, recent evidence suggests developmental hypoxia produces stress-tolerant phenotypes in some ectothermic vertebrates. Embryonic common snapping turtles (Chelydra serpentina) subjected to chronic hypoxia display improved cardiac anoxia tolerance after hatching, which is associated with altered Ca2+ homeostasis in heart cells (cardiomyocytes).

The ontogeny of white leghorn chicken (Gallus domesticus) blood chemistry changes in response to acute exposure to 10 % O.

The embryonic chicken is a valuable model for studying the maturation of cardiovascular physiology and the responses of this organ system to environmental manipulations such as acute hypoxia. Hypoxia determines not only the general cardiovascular response but also is a tool to determine the system's maturation of reflexive control. Several studies suggest embryonic chicken's regulation of the cardiovascular response to hypoxia, but no studies have measured the blood chemistry changes that accompany these responses.

Temperature effects on blood gases in embryonic American alligators (Alligator mississippiensis).

Numerous studies report on the influence of temperature on blood gases in ectothermic vertebrates, but there is merely a cursory understanding of these effects in developing animals. Animals that develop in eggs are at the mercy of environmental temperature and are expected to lack the capacity to regulate gas exchange and may regulate blood gases by means of altered conductance for gas exchange. We, therefore, devised a series of studies to characterize the developmental changes in blood gases when embryonic alligators were exposed to 25, 30 and 35 °C.

Developmental plasticity of the cardiovascular system in oviparous vertebrates: effects of chronic hypoxia and interactive stressors in the context of climate change.

Animals at early life stages are generally more sensitive to environmental stress than adults. This is especially true of oviparous vertebrates that develop in variable environments with little or no parental care. These organisms regularly experience environmental fluctuations as part of their natural development, but climate change is increasing the frequency and intensity of these events.

Shell shape does not accurately predict self-righting ability in hatchling freshwater turtles.

Flat hydrodynamic shells likely represent an evolutionary trade-off between adaptation to an aquatic lifestyle and the instability of more rounded shells, thought beneficial for self-righting. Trade-offs often result in compromises, this is particularly true when freshwater turtles, with flatter shells, must self-right to avoid the negative effects of inverting. These turtles, theoretically, invest more biomechanical effort to achieve successful and timely self-righting when compared to turtles with rounded carapaces.

Short communication: Characterizing arterial and venous blood gases over the gas exchange surface, the chorioallantoic membrane, of embryonic American alligators (Alligator mississippiensis) at two points of development.

Assessments of arterial and venous blood gases are required to understand the function of respiratory organs in animals at different stages of development. We measured blood gases in the arteries entering and veins leaving the chorioallantoic membrane (CAM) in embryonic alligators (Alligator mississippiensis). The CAM accounts for virtually all gas exchange in these animals, and we hypothesized that the CAM vasculature would be larger in eggs incubated in hypoxia (10% O for 50% or 70% of incubation), which would be reflected in a lower partial pressure of CO (PCO).

Short communication: Baroreflex function in embryonic emus (Dromiceius novaehollandiae).

The baroreflex involves cardiovascular homeostatic mechanisms that buffer the system against acute deviations in arterial blood pressure. It is comprised of the cardiac limb which involves adjustments in heart rate and the peripheral limb which involves adjustments in vascular resistance. This negative feedback loop mechanism has been investigated in numerous species of adult vertebrates, however our understanding of the maturation and functional importance of the reflex in developing animals remains poorly understood.

Cardiovascular physiology of embryonic neotropic cormorants (Phalacrocorax brasilianus).

Cardiovascular maturation in avian species has primarily been studied in precocial species of birds, with few studies conducted on altricial species, which make up the majority of avian species. In the precocial species of birds studied to date, cardiovascular regulation is derived primarily from an adrenergic receptor stimulation that is present from approximately 50% to 60% of incubation until hatching. Conversely, the cholinergic modulation of heart rate differs in its timing of activation, as it is reported to be present in some studies at 60% of incubation to as late as after hatching in others.

Do air-breathing fish suffer branchial oxygen loss in hypoxic water?

In hypoxia, air-breathing fish obtain O from the air but continue to excrete CO into the water. Consequently, it is believed that some O obtained by air-breathing is lost at the gills in hypoxic water. is an air-breathing catfish with very large gills from the Mekong River basin where it is cultured in hypoxic ponds.

Hypoxic incubation at 50% of atmospheric levels shifts the cardiovascular response to acute hypoxia in American alligators, Alligator mississippiensis.

We designed a series of studies to investigate whether hypoxia (10% O) from 20% of incubation to hatching, or from 20 to 50% of incubation, affects cardiovascular function when juvenile American alligators reached an age of 4-5 years compared to juveniles that were incubated in 21% O. At this age, we measured blood flows in all the major arteries as well as heart rate, blood pressure, and blood gases in animals in normoxia and acute hypoxia (10% O and 5% O). In all three groups, exposure to acute hypoxia of 10% O caused a decrease in blood O concentration and an increase in heart rate in 4-5-year-old animals, with limited effects on blood flow in the major outflow vessels of the heart.

Detection of Orientia spp. Bacteria in Field-Collected Free-Living Eutrombicula Chigger Mites, United States.

Scrub typhus, a rickettsial disease caused by Orientia spp., is transmitted by infected larval trombiculid mites (chiggers). We report the molecular detection of Orientia species in free-living Eutrombicula chiggers collected in an area in North Carolina, USA, to which spotted fever group rickettsiae infections are endemic.

Exposure to hypoxia during embryonic development affects blood flow patterns and heart rate in juvenile American alligators during digestion.

The developmental environment can alter an organism's phenotype through epigenetic mechanisms. We incubated eggs from American alligators in 10% O (hypoxia) to investigate the functional plasticity of blood flow patterns in response to feeding later in life. Digestion is associated with marked elevations of metabolism, and we therefore used the feeding-induced stimulation of tissue O demand to determine whether there are lasting effects of developmental hypoxia on the cardiovascular response to digestion later in life.

Effects of Developmental Hypoxia on the Vertebrate Cardiovascular System.

Developmental hypoxia has profound and persistent effects on the vertebrate cardiovascular system, but the nature, magnitude, and long-term outcome of the hypoxic consequences are species specific. Here we aim to identify common and novel cardiovascular responses among vertebrates that encounter developmental hypoxia, and we discuss the possible medical and ecological implications.

Developmental oxygen preadapts ventricular function of juvenile American alligators, .

Developmental oxygen is a powerful stressor that can induce morphological and functional changes in the cardiovascular systems of embryonic and juvenile vertebrates. This plasticity has been ascribed, at least in part, to the unique status of the developing cardiovascular system, which undergoes organogenesis while meeting the tissue oxygen demands of the embryo. We have previously reported an array of functional and morphological changes in embryonic American alligators that persist into juvenile life.

Mediterranean Spur-Thighed Tortoises () Have Optimal Speeds at Which They Can Minimise the Metabolic Cost of Transport, on a Treadmill.

Tortoises are famed for their slow locomotion, which is in part related to their herbivorous diet and the constraints imposed by their protective shells. For most animals, the metabolic cost of transport (CoT) is close to the value predicted for their body mass. Testudines appear to be an exception to this rule, as previous studies indicate that, for their body mass, they are economical walkers.

Acute CO tolerance in fishes is associated with air breathing but not the Root effect, red cell βNHE, or habitat.

High CO (hypercapnia) can impose significant physiological challenges associated with acid-base regulation in fishes, impairing whole animal performance and survival. Unlike other environmental conditions such as temperature and O, the acute CO tolerance thresholds of fishes are not understood. While some fish species are highly tolerant, the extent of acute CO tolerance and the associated physiological and ecological traits remain largely unknown.

and Other Species in Chigger Mites Collected from Wild Rodents in North Carolina, USA.

Chiggers are vectors of rickettsial pathogenic bacteria, spp., that cause the human disease, scrub typhus, in the Asian-Pacific area and northern Australia (known as the Tsutsugamushi Triangle). More recently, reports of scrub typhus in Africa, southern Chile, and the Middle East have reshaped our understanding of the epidemiology of this disease, indicating it has a broad geographical distribution.

No evidence for pericardial restraint in the snapping turtle () following pharmacologically induced bradycardia at rest or during exercise.

Most animals elevate cardiac output during exercise through a rise in heart rate (), whereas stroke volume (V) remains relatively unchanged. Cardiac pacing reveals that elevating alone does not alter cardiac output, which is instead largely regulated by the peripheral vasculature. In terms of myocardial oxygen demand, an increase in is more costly than that which would incur if V instead were to increase.

Adrenergic control of the cardiovascular system in deer mice native to high altitude.

Studies of animals native to high altitude can provide valuable insight into physiological mechanisms and evolution of performance in challenging environments. We investigated how mechanisms controlling cardiovascular function may have evolved in deer mice () native to high altitude. High-altitude deer mice and low-altitude white-footed mice () were bred in captivity at sea level, and first-generation lab progeny were raised to adulthood and acclimated to normoxia or hypoxia.

The metabolic cost of turning right side up in the Mediterranean spur-thighed tortoise (Testudo graeca).

Armoured, rigid bodied animals, such as Testudines, must self-right should they find themselves in an inverted position. The ability to self-right is an essential biomechanical and physiological process that influences survival and ultimately fitness. Traits that enhance righting ability may consequently offer an evolutionary advantage.

Changes in hemoglobin function and isoform expression during embryonic development in the American alligator, .

In the developing embryos of egg-laying vertebrates, O flux takes place across a fixed surface area of the eggshell and the chorioallantoic membrane. In the case of crocodilians, the developing embryo may experience a decrease in O flux when the nest becomes hypoxic, which may cause compensatory adjustments in blood O transport. However, whether the switch from embryonic to adult hemoglobin isoforms (isoHbs) plays some role in these adjustments is unknown.

Developmental programming of DNA methylation and gene expression patterns is associated with extreme cardiovascular tolerance to anoxia in the common snapping turtle.

Background: Environmental fluctuation during embryonic and fetal development can permanently alter an organism's morphology, physiology, and behaviour. This phenomenon, known as developmental plasticity, is particularly relevant to reptiles that develop in subterranean nests with variable oxygen tensions. Previous work has shown hypoxia permanently alters the cardiovascular system of snapping turtles and may improve cardiac anoxia tolerance later in life.