Explore the vast range of titles available.

Animals native to the hypoxic and cold environment at high altitude provide an excellent opportunity to elucidate the integrative mechanisms underlying the adaptive evolution and plasticity of complex traits. The capacity for aerobic thermogenesis can be a critical determinant of survival for small mammals at high altitude, but the physiological mechanisms underlying the evolution of this performance trait remain unresolved. We examined this issue by comparing high-altitude deer mice (Peromyscus maniculatus) with low-altitude deer mice and white-footed mice (P. leucopus). Mice were bred in captivity and adults were acclimated to each of four treatments: warm (25°C) normoxia, warm hypoxia (12 kPa O₂), cold (5°C) normoxia or cold hypoxia. Acclimation to hypoxia and/or cold increased thermogenic capacity in deer mice, but hypoxia acclimation led to much greater increases in thermogenic capacity in highlanders than in lowlanders. The high thermogenic capacity of highlanders was associated with increases in pulmonary O₂ extraction, arterial O₂ saturation, cardiac output and arterial–venous O₂ difference. Mechanisms underlying the evolution of enhanced thermogenic capacity in highlanders were partially distinct from those underlying the ancestral acclimation responses of lowlanders. Environmental adaptation has thus enhanced phenotypic plasticity and expanded the physiological toolkit for coping with the challenges at high altitude.

Animals native to the hypoxic and cold environment at high altitude provide an excellent opportunity to elucidate the integrative mechanisms underlying the adaptive evolution and plasticity of complex traits. The capacity for aerobic thermogenesis can be a critical determinant of survival for small mammals at high altitude, but the physiological mechanisms underlying the evolution of this performance trait remain unresolved. We examined this issue by comparing high-altitude deer mice ( Peromyscus maniculatus ) with low-altitude deer mice and white-footed mice ( P. leucopus ). Mice were bred in captivity and adults were acclimated to each of four treatments: warm (25°C) normoxia, warm hypoxia (12 kPa O 2 ), cold (5°C) normoxia or cold hypoxia. Acclimation to hypoxia and/or cold increased thermogenic capacity in deer mice, but hypoxia acclimation led to much greater increases in thermogenic capacity in highlanders than in lowlanders. The high thermogenic capacity of highlanders was associated with increases in pulmonary O 2 extraction, arterial O 2 saturation, cardiac output and arterial–venous O 2 difference. Mechanisms underlying the evolution of enhanced thermogenic capacity in highlanders were partially distinct from those underlying the ancestral acclimation responses of lowlanders. Environmental adaptation has thus enhanced phenotypic plasticity and expanded the physiological toolkit for coping with the challenges at high altitude.

Environmental conditions fluctuate dramatically in some reptilian nests. However, critical windows of environmental sensitivity for cardiovascular development have not been identified. Continuous developmental hypoxia has been shown to alter cardiovascular form and function in embryonic snapping turtles (Chelydra serpentina), and we used this species to identify critical periods during which hypoxia modifies the cardiovascular phenotype. We hypothesized that incubation in 10% O2during specific developmental periods would have differential effects on the cardiovascular system versus overall somatic growth. Two critical windows were identified with 10% O2from 50% to 70% of incubation, resulting in relative heart enlargement, either via preservation of or preferential growth of this tissue, while exposure to 10% O2from 20% to 70% of incubation resulted in a reduction in arterial pressure. The deleterious or advantageous aspects of these embryonic phenotypes in posthatching snapping turtles have yet to be explored. However, identification of these critical windows has provided insight into how the developmental environment alters the phenotype of reptiles and will also be pivotal in understanding its impact on the fitness of egg-laying reptiles.

Experiments addressing the role of plant species diversity for ecosystem functioning have recently proliferated. Most studies have focused on plant biomass responses. However, microbial processes involved in the production of N2O and the oxidation of atmospheric CH4 could potentially be affected via effects on N cycling, on soil diffusive properties (due to changes in water relations and root architecture) and by more direct interactions of plants with soil microbes. We studied ecosystem-level CH4 and N2O fluxes in experimental communities assembled from two pasture soils and from combinations of 1, 3, 6, 8 or 9 species typical for these pastures. The soils contrasted with respect to texture and fertility. N2O emissions decreased with diversity and increased in the presence of legumes. Soils were sinks for CH4 at all times; legume monocultures were a smaller sink for atmospheric CH4 than non-legume monocultures, but no effect of species richness per se was detected. However, both the exchange of CH4 and N2O strongly depended on plant community composition, and on the interaction of composition with soil type, indicating that the functional role of species and their interactions differed between soils. N2O fluxes were mainly driven by effects on soil nitrate and on nitrification while soil moisture had less of an effect. Soil microbial C and N and N mineralisation rates were not altered. The driver of the interactive soil type × plant community composition-effects was less clear. Because soil methanotrophs may take longer to respond to alterations of N cycling than the 1/2 year treatment in this study, we also tested species richness-effects in two separate 5-year field studies, but results were ambiguous, indicating complex interactions with soil disturbance. In conclusion, our study demonstrates that plant community composition can affect the soil trace gas balance, whereas plant species richness per se was less important; it also indicates a potential link between the botanical composition of plant communities and global warming.

Angiotensin II (ANG II) is a powerful vasoconstrictor of the renin–angiotensin system (RAS) that plays an important role in cardiovascular regulation in adult and developing vertebrates. Knowledge of ANG II’s contribution to developmental cardiovascular function comes from studies in fetal mammals and embryonic chickens. This is the first study to examine the role of ANG II in cardiovascular control in an embryonic reptile, the American alligator (Alligator mississippiensis). Using chronic low (~ 5-mg kg embryo−1), or high doses (~ 450-mg kg embryo−1) of captopril, an angiotensin-converting enzyme (ACE) inhibitor, we disrupted the RAS and examined the influence of ANG II in cardiovascular function at 90% of embryonic development. Compared to embryos injected with saline, mean arterial pressure (MAP) was significantly reduced by 41 and 72% under low- and high-dose captopril treatments, respectively, a greater decrease in MAP than observed in other developing vertebrates following ACE inhibition. Acute exogenous ANG II injection produced a stronger hypertensive response in low-dose captopril-treated embryos compared to saline injection embryos. However, ACE inhibition with the low dose of captopril did not change adrenergic tone, and the ANG II response did not include an α-adrenergic component. Despite decreased MAP that caused a left shifted baroreflex curve for low-dose captopril embryos, ANG II did not influence baroreflex sensitivity. This study demonstrates that ANG II contributes to cardiovascular function in a developing reptile, and that the RAS contributes to arterial blood pressure maintenance during development across multiple vertebrate groups.

American alligators (Alligator mississippiensis) deposit eggs in a mound nest, potentially subjecting embryos to daily variations in temperature. Whilst adult crocodilian cardiovascular responses to changes in temperature have been investigated, similar studies in alligator embryos are limited. We investigated cardiovascular function of embryonic alligators during heating and cooling as well as at different temperatures. We measured arterial blood pressure (Pm) and heart rate (fH) in response to cooling (30–26 °C), heating (26–36 °C), followed by a reciprocal cooling event (36–26 °C) and assessed the cardiac baroreflex at 30 and 36 °C. Embryonic fH increased during heating events and decreased during cooling events, while embryos were hypotensive at 26 and 36 °C, although Pm did not differ between heating or cooling events. There was a clear temperature-dependent heart rate hysteresis at a given embryo’s temperature, depending on whether embryos were cooling or heating. Cardiovascular regulation through the cardiac limb of the baroreflex was not affected by temperature, despite previous studies suggesting that vagal tone is present at both low and high temperatures.

Methanotrophs use methane (CH 4 ) as a carbon source. They are particularly active in temperate forest soils. However, the rate of change of CH 4 oxidation in soil with afforestation or reforestation is poorly understood. Here, soil CH 4 oxidation was examined in New Zealand volcanic soils under regenerating native forests following burning, and in a mature native forest. Results were compared with data for pasture to pine land-use change at nearby sites. We show that following soil disturbance, as little as 47 years may be needed for development of a stable methanotrophic community similar to that in the undisturbed native forest soil. Corresponding soil CH 4 -oxidation rates in the regenerating forest soil have the potential to reach those of the mature forest, but climo-edaphic fators appear limiting. The observed changes in CH 4 -oxidation rate were directly linked to a prior shift in methanotrophic communities, which suggests microbial control of the terrestrial CH 4 flux and identifies the need to account for this response to afforestation and reforestation in global prediction of CH 4 emission.

Research on calling has examined the presence of and search for career calling. This cross‐sectional study investigated the relationship between family influence and career calling (presence and search) in a sample of 400 women of color (mean age = 31.2 years) in the United States. The authors also examined whether this relationship was partially or fully explained by critical consciousness. Participants were recruited using Amazon Mechanical Turk, where they completed an online questionnaire. Structural equation modeling was used to test 2 models, with calling presence and calling search as disparate outcomes. Analyses revealed that most of the significant pathways in the model involved family influence, critical consciousness, and calling search. In addition, findings suggested that critical consciousness did not explain the relationship between family influence and career calling (presence or search); however, given the significant pathways, it may still be an important consideration for counselors when working with women of color on their career development.

Rosacea is a chronic cutaneous condition with a prevalence rate ranging from 9.6% to 22% in recent studies. Facial erythema (transient and permanent) is considered a common denominator that is frequently observed in all subtypes of rosacea and is estimated to affect more than 40 million people worldwide. Brimonidine tartrate is a selective α2-adrenergic receptor agonist and is the first topical treatment approved for facial erythema of rosacea. Clinical trials have demonstrated that brimonidine tartrate provided significantly greater efficacy, compared to vehicle, for the treatment of moderate to severe erythema of rosacea. In addition, brimonidine tartrate has demonstrated a rapid onset of effect, duration of action throughout the day, and good safety profile in studies of up to 1 year. This review critically discusses the role of brimonidine tartrate for the treatment of facial erythema of rosacea by examining both clinical study data and real-world dermatologist experiences across a wide spectrum of treated patients, and concludes that it is a significant therapeutic option in the management of an unmet need of this chronic condition.

Soil methane (CH4) biofilters, containing CH4–oxidizing bacteria (methanotrophs), are a promising technology for mitigating greenhouse gas emissions. However, little is known about long‐term biofilter performance. In this study, volcanic pumice topsoils (0–10 cm) and subsoils (10–50 cm) were tested for their ability to oxidize a range of CH4 fluxes over 1 yr. The soils were sampled from an 8‐yr‐old and a 2‐yr‐old grassed landfill cover and from a nearby undisturbed pasture away from the influence of CH4 generated by the decomposing refuse. Methane was passed through the soils in laboratory chambers with fluxes ranging from 0.5 g to 24 g CH4 m−3 h−1. All topsoils efficiently oxidized CH4. The undisturbed pasture topsoil exhibited the highest removal efficiency (24 g CH4 m−3 h−1), indicating rapid activation of the methanotroph population to the high CH4 fluxes. The subsoils were less efficient at oxidizing CH4 than the topsoils, achieving a maximum rate oxidation rate of 7 g CH4 m−3 h−1. The topsoils exhibited higher porosities; moisture contents; surface areas; and total C, N, and available‐P concentrations than the subsoils, suggesting that these characteristics strongly influence growth and activity of the CH4–oxidizing bacteria. Soil pH values and available‐P levels gradually declined during the trial, indicating a need to monitor chemical parameters closely so that adjustments can be made when necessary. However, other key soil physicochemical parameters (moisture, total C, total N) increased over the course of the trial. This study showed that the selected topsoils were capable of continually sustaining high CH4 removal rates over 1 yr, which is encouraging for the development of biofilters as a low‐maintenance greenhouse gas mitigation technology.