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There is great interspecific variation in the nutritional composition of natural diets, and the varied nutritional content is physiologically tolerated because of evolutionarily based balances between diet composition and processing ability. However, as a result of landscape change and human exposure, unnatural diets are becoming widespread among wildlife without the necessary time for evolutionary matching between the diet and its processing. We tested how a controlled, unnatural high glucose diet affects glucose tolerance using captive green iguanas, and we performed similar glucose tolerance tests on wild Northern Bahamian rock iguanas that are either frequently fed grapes by tourists or experience no such supplementation. We evaluated both short and longer-term blood glucose responses and corticosterone (CORT) concentrations as changes have been associated with altered diets. Experimental glucose supplementation in the laboratory and tourist feeding in the wild both significantly affected glucose metabolism. When iguanas received a glucose-rich diet, we found greater acute increases in blood glucose following a glucose challenge. Relative to unfed iguanas, tourist-fed iguanas had significantly lower baseline CORT, higher baseline blood glucose, and slower returns to baseline glucose levels following a glucose challenge. Therefore, unnatural consumption of high amounts of glucose alters glucose metabolism in laboratory iguanas with short-term glucose treatment and free-living iguanas exposed to long-term feeding by tourists. Based on these results and the increasing prevalence of anthropogenically altered wildlife diets, the consequences of dietary changes on glucose metabolism should be further investigated across species, as such changes in glucose metabolism have health consequences in humans (e.g. diabetes).

Hyperpigmented melanistic skin lesions (HPMLs) of smallmouth bassMicropterus dolomieuare observed in the Potomac and Susquehanna rivers, Chesapeake Bay watershed, USA. Routine, nonlethal population surveys were conducted at 8 sites on the mainstem Susquehanna River and 9 on the Juniata River, a tributary of the Susquehanna River, between 2012 and 2018, and the prevalence of HPMLs was documented. A total of 4078 smallmouth bass were collected from the mainstem Susquehanna River and 6478 from the Juniata River. Lesions were primarily seen in bass greater than 200 mm, and prevalence in the Susquehanna River (8%) was higher (p < 0.001) than in the Juniata River (2%). As part of ongoing fish health monitoring projects, smallmouth bass were collected at additional sites, primarily tributaries of the Susquehanna (n = 758) and Potomac (n = 545) rivers between 2013 and 2018. Prevalence in the Susquehanna River (13%) was higher (p < 0.001) than the Potomac (3%). Microscopically, HPMLs were characterized by an increased number of melanocytes in the epidermis or within the dermis and epidermis. RNAseq analyses of normal and melanistic skin identified 3 unique sequences in HPMLs. Two were unidentified and the third was a viral helicase (E1). Transcript abundance in 16 normal skin samples and 16 HPMLs showed upregulation of genes associated with melanogenesis and cell proliferation in HPMLs. The E1 transcript was detected in 12 of the 16 melanistic areas but in no samples from normal skin. Further research will be necessary to identify the putative new virus and determine its role in melanocyte proliferation.

Significance Absorption by black carbon strongly affects regional and global climate. Yet, large discrepancies between standard model predictions and regionally specific observations—often with observed absorption lower than expected—raise questions about current understanding of black carbon absorption and its atmospheric impacts. Through a combination of measurement and modeling, our analysis resolves the discrepancy by showing that particular laboratory designs or atmospheric conditions engender distinct compositional heterogeneity among particles containing black carbon. Lower-than-expected absorption results largely from increased heterogeneity, although slightly lowered absorption occurs even in a purely homogeneous system. This work provides a framework that explains globally disparate observations and that can be used to improve estimates of black carbon’s global impact., Black carbon (BC) absorbs solar radiation, leading to a strong but uncertain warming effect on climate. A key challenge in modeling and quantifying BC’s radiative effect on climate is predicting enhancements in light absorption that result from internal mixing between BC and other aerosol components. Modeling and laboratory studies show that BC, when mixed with other aerosol components, absorbs more strongly than pure, uncoated BC; however, some ambient observations suggest more variable and weaker absorption enhancement. We show that the lower-than-expected enhancements in ambient measurements result from a combination of two factors. First, the often used spherical, concentric core-shell approximation generally overestimates the absorption by BC. Second, and more importantly, inadequate consideration of heterogeneity in particle-to-particle composition engenders substantial overestimation in absorption by the total particle population, with greater heterogeneity associated with larger model–measurement differences. We show that accounting for these two effects—variability in per-particle composition and deviations from the core-shell approximation—reconciles absorption enhancement predictions with laboratory and field observations and resolves the apparent discrepancy. Furthermore, our consistent model framework provides a path forward for improving predictions of BC’s radiative effect on climate.

We compared the imaginary part of the refractive indices (k) of brown carbon (BrC) retrieved from online and solvent-extraction offline light-absorption measurements. BrC with variable light-absorption properties was generated from the controlled combustion of three structurally different fuels: toluene (aromatic), isooctane (branched alkane), and cyclohexane (cyclic alkane). The online retrieval method involved combining real-time measurements of aerosol absorption coefficients (at 422, 532, and 781 nm) and size distributions with Mie calculations. The offline method involved extracting BrC samples with two organic solvents, methanol and dichloromethane, followed by light-absorption measurements of the extracts using a UV-vis spectrophotometer. For the least absorbing BrC, k values of the extracts in both solvents were similar to those of the aerosol. However, for darker BrC, k values of the BrC extracts in dichloromethane were smaller than those of the BrC aerosol, and k values of the BrC extracts in methanol were the smallest, with the discrepancy among the three increasing with increasing BrC darkness. These results indicate that BrC produced in this study was more soluble in dichloromethane than methanol, and the BrC solubility in both solvents decreased with increasing BrC darkness. Finally, k of BrC aerosol and extracts followed the same trend of decreasing wavelength dependence with increasing k as previous data. This further supports the brown-black continuum of light-absorption properties and that the differences observed between k of the BrC aerosol and extracts are due to the inefficiency of solvent extraction and not due to intrinsic differences between the online and offline methods. Copyright © 2020 American Association for Aerosol Research

ObjectiveFlathead catfish are rapidly expanding into nonnative waterways throughout the United States. Once established, flathead catfish may cause disruptions to the local ecosystem through consumption and competition with native fishes, including species of conservation concern. Flathead catfish often become a popular sport fish in their introduced range, and so management strategies must frequently balance the need to protect native and naturalized fauna while meeting the desire to maintain or enhance fisheries. However, there are currently few tools available to inform management of invasive flathead catfish (Pylodictis olivaris). We describe a suite of microsatellite loci that can be used to characterize population structure, predict invasion history, and assess potential mitigation strategies for flathead catfish.ResultsOur panel of 13 microsatellite loci were polymorphic and appear to be informative for population genetic studies of flathead catfish. We found moderate levels of diversity in four nonnative collections of flathead catfish in the Pennsylvania and Maryland sections of the Susquehanna River and the Schuylkill River, Pennsylvania. Analyses suggested patterns of genetic differentiation within- and among-rivers, highlighting the utility of this marker panel for understanding the structure and assessing the degree of connectivity among flathead catfish populations.

Life‐history strategies are known to shift with latitude in many species. While life‐history variation related to body size, reproductive investment, and behavior has been studied for years, another crucial life‐history component is the immune system, which can influence an animal's survival. We measured selected life‐history traits in side‐blotched lizards in southern Utah and Oregon in the field for two consecutive years and conducted a common‐garden experiment in the laboratory to determine how organisms from different latitudes optimize either immunity or reproduction. We observed lizards from southern populations, which are known to be shorter‐lived, had lower immune function during reproduction when compared to northern lizards in 2012, but the relationship reversed in the following year. Our laboratory study revealed that southern lizards healed cutaneous wounds faster and had higher microbiocidal ability when compared to their northern counterparts, but lost mass doing so. The northern lizards ate more than the southern ones and maintained their body mass. It is possible that northern lizards are better adapted to taking advantage of available food resources. Alternatively, southern lizards may have exhibited sickness behavior in response to an immune challenge or reacted more strongly to the stress of captivity. We found differences in life‐history strategies used by animals from different latitudes, and that these changes can shift within a population depending on the weather conditions of the year. Furthermore, when taken from the field and placed into a common‐garden environment, some of these differences in strategy appear to be intrinsic to the animals (i.e., whether they came from southern or northern populations).

Management of stressors requires an understanding of how multiple stressors interact, how different species respond to those interactions and the underlying mechanisms driving observed patterns in species’ responses. Salinization and rising temperatures are two pertinent stressors predicted to intensify in freshwater ecosystems, posing concern for how susceptible organisms achieve and maintain homeostasis (i.e. allostasis). Here, glucocorticoid hormones (e.g. cortisol), responsible for mobilizing energy (e.g. glucose) to relevant physiological processes for the duration of stressors, are liable to vary in response to the duration and severity of salinization and temperature rises. With field and laboratory studies, we evaluated how both salinity and temperature influence basal and stress-reactive cortisol and glucose levels in age 1+ mottled sculpin (Cottus bairdii), mountain sucker (Catostomus platyrhynchus) and Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus). We found that temperature generally had the greatest effect on cortisol and glucose concentrations and the effect of salinity was often temperature dependent. We also found that when individuals were chronically exposed to higher salinities, baseline concentrations of cortisol and glucose usually declined as salinity increased. Reductions in baseline concentrations facilitated stronger stress reactivity for cortisol and glucose when exposed to additional stressors, which weakened as temperatures increased. Controlled temperatures near the species’ thermal maxima became the overriding factor regulating fish physiology, resulting in inhibitory responses. With projected increases in freshwater salinization and temperatures, efforts to reduce the negative effects of increasing temperatures (i.e. increased refuge habitats and riparian cover) could moderate the inhibitory effects of temperature-dependent effects of salinization for freshwater fishes.

Low-grade endometrial stromal sarcoma (LGESS) is a rare malignant uterine tumor with the potential to metastasize years after the primary resection. There is a broad differential diagnosis for endometrial stromal sarcomas (ESS), including both benign and malignant entities. Herein, we present the case of a 64-year-old female with metastatic LGESS to the lung, diagnosed by cytology, 24 years after her initial presentation. This report discusses the cytomorphologic and histopathologic characteristics, and ancillary studies including immunohistochemical stains and recent advances in molecular diagnostics of ESS. Accurate diagnosis of spindle cell lesions in the lung can be challenging. As such, this case highlights the instrumental role of ancillary testing and molecular diagnostics to achieve a more definitive diagnosis.

While there is huge promise in monitoring physiological parameters in free-living organisms, we also find high amounts of variability over time and space. This variation requires us to capitalize on long-term physiological monitoring to adequately address questions of population health, conservation status, or evolutionary trends as long-term sampling can examine ecoimmunological and endocrine interactions in wild populations while accounting for the variation that often makes ecophysiological field studies difficult to compare. In this study, we tested how immune efficacy and endocrinology interact while accounting for ecological context and environmental conditions in two snake species. Specifically, we measured bacterial killing ability, steroid hormones, and morphological characteristics in multiple populations of the Western Terrestrial Gartersnake (Thamnophis elegans) and Common Gartersnake (T. sirtalis) for multiple seasons over 6 years. Leveraging this long-term dataset, we tested how a broad immune measure and endocrine endpoints interact while accounting for individual traits, sampling date, and environmental conditions. Across both species, we found bacterial killing ability to be directly related to corticosterone (CORT) and temperature and greater overall in the spring compared to the fall. We found CORT and testosterone yielded relationships with individual sex, sampling temperature, and time of year. Wild populations can exhibit high amounts of variation in commonly collected physiological endpoints, highlighting the complexity and difficulty inherent in interpreting single endpoints without taking ecological and environmental conditions into account. Our study emphasizes the importance of reporting the environmental conditions under which the sampling occurred to allow for better contextualization and comparison between studies.

Raised mucoid skin lesions have been observed on smallmouth bass (Micropterus dolomieu) for years. Here, we report the draft genome of a novel adomavirus (Micropterus dolomieu adomavirus 2) associated with this disease. The circular genome is 17,561 bp and most similar to that of alpha-adomaviruses.

Lay Summary The chemical signatures of the bodies of lizards contain information about what they eat. We compared lizard chemical signatures between urban and rural areas in southern Utah and found that they have much broader diets in urban areas and that some chemical signatures were related to reproduction., Spatial and temporal variation in stoichiometric and stable isotope ratios of animals contains ecological information that we are just beginning to understand. In both field and lab studies, stoichiometric or isotopic ratios are related to physiological mechanisms underlying nutrition or stress. Conservation and ecosystem ecology may be informed by isotopic data that can be rapidly and non-lethally collected from wild animals, especially where human activity leaves an isotopic signature (e.g. via introduction of chemical fertilizers, ornamental or other non-native plants or organic detritus). We examined spatial and temporal variation in stoichiometric and stable isotope ratios of the toes of Uta stansburiana (side-blotched lizards) living in urban and rural areas in and around St. George, Utah. We found substantial spatial and temporal variation as well as context-dependent co-variation with reproductive physiological parameters, although certain key predictions such as the relationship between δ15N and body condition were not supported. We suggest that landscape change through urbanization can have profound effects on wild animal physiology and that stoichiometric and stable isotope ratios can provide unique insights into the mechanisms underlying these processes.

A myxozoan parasite, Myxobolus inornatus, is one disease agent identified in young of the year (YOY) smallmouth bass in the Susquehanna River Basin, Pennsylvania. We investigated spatial and temporal variability in M. Inornatus prevalence across the Susquehanna River Basin and at several out-of-basin sites. We examined potential land use drivers of M. Inornatus prevalence including agricultural and developed land use. In 1,267 YOY smallmouth bass collected from 32 sites during 2013-2016, M. Inornatus was documented in 43.6% of samples. Among-site variability in parasite prevalence was greater than among-year variability. The effect of agricultural land use on M. Inornatus prevalence had a high probability of being positively correlated at multiple spatial scales (probability of positive effect > 0.80). The effect of developed land use on M. Inornatus prevalence had a relatively high probability of being negatively correlated at multiple spatial scales (probability of negative effect > 0.70). Our results suggest that land use practices could be related to M. Inornatus infection of smallmouth bass. Further study will be necessary to determine whether disease dynamics are a consequence of effects on the host, alterations of instream habitat mediating invertebrate host dynamics and/or survival and dispersal of the parasite infective stage.

Behavioral fever in reptiles is often considered an adaptive response used to eliminate pathogens, yet empirical data showing the wide-spread use of this response is mixed. This behavioral change can be beneficial by enhancing the host’s immune response and increasing the animal’s chance of survival, but it can also be detrimental in terms of host energetic requirements and enzymatic performance. Thus, we examined whether captive-bred African house snakes (Lamprophis fuliginosus) employed behavioral fever in response to pathogen stimulus. Twenty-one African house snakes were injected separately with three different strains of ultraviolet (UV) light-killed bacteria (Escherichia coli, Staphylococcus aureus, Salmonella enterica). We found an increased variance of hourly cloacal temperatures following exposure to pathogens in male but not female house snakes. We did not, however, find a significant febrile response to pathogen exposure as measured via mean cloacal temperature. This research adds critical information to the field of reptilian physiology as this field remains understudied. Reptilian immune function and its relationship with thermal biology is ever more pertinent as new challenges arise, such as novel pathogens and changing climate.

Background Mortality episodes have affected young-of-year smallmouth bass (Micropterus dolomieu) in several river systems in Pennsylvania since 2005. A series of laboratory experiments were performed to determine the potential role of largemouth bass virus (Ranavirus, Iridoviridae) in causing these events. Results Juvenile smallmouth bass experimentally infected with the largemouth bass virus exhibited internal and external clinical signs and mortality consistent with those observed during die-offs. Microscopically, infected fish developed multifocal necrosis in the mesenteric fat, liver, spleen and kidneys. Fish challenged by immersion also developed severe ulcerative dermatitis and necrotizing myositis and rarely panuveitis and keratitis. Largemouth bass virus-challenged smallmouth bass experienced greater mortality at 28 °C than at 23 or 11 °C. Co-infection with Flavobacterium columnare at 28 °C resulted in significant increase in mortality of smallmouth bass previously infected with largemouth bass virus. Aeromonas salmonicida seems to be very pathogenic to fish at water temperatures

Aerosols directly affect Earth's climate by scattering and absorbing solar radiation. Although they are ubiquitous in Earth's atmosphere, direct, in situ, wavelength-resolved measurements of aerosol optical properties remain challenging. As a result, the so-called aerosol direct effects are one of the largest uncertainties in predictions of Earth's future climate, and new instrumentation is needed to provide measurements of the absorption of sunlight by atmospheric particles. We have developed a portable, four-wavelength, single-cell photoacoustic spectrometer for simultaneous measurement of aerosol absorption at 406, 532, 662, and 785 nm, with an additional extinction measurement at 662 nm via a built-in cavity ringdown spectrometer. The instrument, dubbed MultiPAS-IV, is compact, robust, has low power requirements, and utilizes a multipass optical arrangement to achieve typical detection limits of 0.6–0.7 Mm−1 for absorption (2σ, 2-min average). Tests with nigrosin aerosols show agreement with Mie theory calculations to within 2%, and comparison with a 7-wavelength aethalometer shows good correlation for ambient (Athens, GA, USA) aerosols. We demonstrate the utility of the broad spectral coverage and sensitivity of the MultiPAS-IV for calculating the absorption Ångström exponent of black carbon (AAEBC, median value of 0.70) in ambient aerosols and use this value to derive the brown carbon contributions to absorption at 406 nm (43%) and 532 nm (13%) and its wavelength dependence (AAEBrC = 6.3). Copyright © 2018 American Association for Aerosol Research

SYNOPSIS The immune system is a critical component of health and fitness, whereby organisms must maintain sufficient health to survive to reproduce. Because of the key role of immunity in an organism's fitness, the use of immunological indices is widespread. However, there is a paucity of empirical support for the best way to interpret immunological data, and the internal energetic state of the organism, as well as the external environmental pressures it faces, are often not considered concurrently. A stronger immune response is not always beneficial to the organism; a more attenuated response may ultimately lead to improved fitness if the animal incurs fewer performance costs on competing systems, especially reproduction. Additionally, the external pressures animals encounter (such as anthropogenic disturbance) must be considered along with the animal's internal state. A synthesis of results addressing resource allocation between the immune and reproductive systems is presented using a well-studied organism, the side-blotched lizard, from a combination of field and laboratory studies under varying environmental conditions. Specifically, experiments involving specific immune, reproductive, metabolic, and performance costs in a laboratory setting are discussed, as well as associated demographic trade-offs between survival and reproductive success, demonstrating essential links between immunity and the population.

Assessing the health and condition of animals in their natural environment can be problematic. Many physiological metrics, including immunity, are highly influenced by specific context and recent events to which researchers may be unaware. Thus, using a multifaceted physiological approach and a context-specific analysis encompassing multiple time scales can be highly informative. Ecoimmunological tools in particular can provide important indications to the health of animals in the wild. We collected blood and hair samples from free-ranging polar bears (Ursus maritimus) in the southern Beaufort Sea and examined the influence of sex, age, and reproductive status on metrics of immunity, stress, and body condition during 2013-2015. We examined metrics of innate immunity (bactericidal ability and lysis) and stress (hair cortisol, reactive oxygen species, and oxidative barrier), in relation to indices of body condition considered to be short term (urea to creatinine ratio; UC ratio) and long term (storage energy and body mass index). We found the factors of sex, age, and reproductive status of the bear were critical for interpreting different physiological metrics. Additionally, the metrics of body condition were important predictors for stress indicators. Finally, many of these metrics differed between years, illustrating the need to examine populations on a longer time scale. Taken together, this study demonstrates the complex relationship between multiple facets of physiology and how interpretation requires us to examine individuals within a specific context.

Virtual crossmatch (VXM) compares a transplant candidate’s unacceptable antigens to the HLA typing of the donor before an organ offer is accepted and, in selected cases, supplant a prospective physical crossmatch. However, deceased donor typing can be ambiguous, leading to uncertainty in compatibility prediction. We have developed a web application that utilizes ambiguous HLA molecular typing data to assist in VXM assessments. The application compares a candidate’s listed unacceptable antigens to computed probabilities of all possible two-field donor HLA alleles and UNOS antigens. The VIrtual CrossmaTch for mOleculaR HLA typing (VICTOR) tool can be accessed at http://www.transplanttoolbox.org/victor. We reanalyzed historical VXM cases where a transplant center’s manual interpretation of molecular typing results influenced offer evaluation. We found that VICTOR’s automated interpretation of ambiguous donor molecular typing data would influence VXM decisions. Standardized interpretation of molecular typing data, if applied to the match run, could also change which offers are made. HLA typing ambiguity has been an underappreciated source of immunological risk in organ transplantation. The VICTOR tool can serve as a testbed for development of allocation policies with the aim of decreasing offers refused due to HLA incompatibility.

While the use of nanoparticles has dramatically increased in recent years, the ecological consequences are not well known. In particular, little research has been done to investigate the potentially detrimental effects of nanoparticles on amphibians, especially across all life-history stages of salamanders and newts (caudates). To address this dearth in knowledge, we examined the effects of zinc oxide (ZnO) nanoparticles on egg, larval, and adult Rough-skinned Newts (Taricha granulosa). Chronic toxicity was tested on eggs and larvae, and acute toxicity was tested on eggs, larvae, and adults. For eggs, chronic exposure to ZnO nanoparticles caused higher mortality at 10.0 and 100.0 mg L(-1) compared to 0.0, 0.1, and 1.0 mg L(-1) . When given an acute exposure (24 hr) to 10.0 mg L(-1) nanoparticles at a late developmental stage, larvae hatched 5 days early, at a decreased developmental stage, and smaller size compared to the control. Chronic and acute exposure of larvae increased mortality up to 75% at both 10.0 and 100.0 mg L(-1) and exhibited sublethal effects, most dramatically, severe gill degradation. These results suggest nanoparticles can have lethal and sublethal effects on all life stages of amphibians.

Photoacoustic spectroscopy (PAS) has become a popular technique for measuring absorption of light by atmospheric aerosols in both the laboratory and field campaigns. It has low detection limits, measures suspended aerosols, and is insensitive to scattering. But PAS requires rigorous calibration to be applied quantitatively. Often, a PAS instrument is either filled with a gas of known concentration and absorption cross section, such that the absorption in the cell can be calculated from the product of the two, or the absorption is measured independently with a technique such as cavity ring-down spectroscopy. Then, the PAS signal can be regressed upon the known absorption to determine a calibration slope that reflects the sensitivity constant of the cell and microphone. Ozone has been used for calibrating PAS instruments due to its well-known UV–visible absorption spectrum and the ease with which it can be generated. However, it is known to photodissociate up to approximately 1120 nm via the O3 + hν(>1.1eV)→O2(3Σg-) + O(3P) pathway, which is likely to lead to inaccuracies in aerosol measurements. Two recent studies have investigated the use of O3 for PAS calibration but have reached seemingly contradictory conclusions with one finding that it results in a sensitivity that is a factor of 2 low and the other concluding that it is accurate. The present work is meant to add to this discussion by exploring the extent to which O3 photodissociates in the PAS cell and the role that the identity of the bath gas plays in determining the PAS sensitivity. We find a 5 % loss in PAS signal attributable to photodissociation at 532 nm in N2 but no loss in a 5 % mixture of O2 in N2. Furthermore, we discovered a dramatic increase of more than a factor of 2 in the PAS sensitivity as we increased the O2 fraction in the bath gas, which reached an asymptote near 100 % O2 that nearly matched the sensitivity measured with both NO2 and nigrosin particles. We interpret this dependence with a kinetic model that suggests the reason for the observed results is a more efficient transfer of energy from excited O3 to O2 than to N2 by a factor of 22–55 depending on excitation wavelength. Notably, the two prior studies on this topic used different bath gas compositions, and although the results presented here do not fully resolve the differences in their results, they may at least partially explain them.

Photoacoustic spectroscopy (PAS) has become a popular technique for measuring absorption of light by atmospheric aerosols in both the laboratory and in field campaigns. It has low detection limits, measures suspended aerosols, and is insensitive to scattering. But PAS requires rigorous calibration to be applied quantitatively. Often, a PAS instrument is either filled with a gas of known concentration and absorption cross section, such that the absorption in the cell can be calculated from the product of the two, or the absorption is measured independently with a technique such as cavity ringdown spectroscopy. Then, the PAS signal can be regressed upon the known absorption to determine a calibration slope that reflects the sensitivity constant of the cell and microphone. Ozone has been used for calibrating PAS instruments due to its well-known UV-visible absorption spectrum and the ease with which it can be generated. However, it is known to photodissociate up to approximately 1120 nm via the O 3 + hν (> 1.1 eV) → O 2 ( 3 ∑ g − ) + O( 3 P) pathway, which is likely to lead to inaccuracies in aerosol measurements. Two recent studies have investigated the use of O 3 for PAS calibration but have reached seemingly contradictory conclusions with one finding that it results in a sensitivity that is a factor of two low and the other concluding that it is accurate. The present work is meant to add to this discussion by exploring the extent to which O 3 photodissociates in the PAS cell and the role that the identity of the bath gas plays in determining the PAS sensitivity. We find a 5 % loss in PAS signal attributable to photodissociation at 532 nm in N 2 but no loss in a 5 % mixture of O 2 in N 2 . Furthermore, we discovered a dramatic increase of more than a factor of two in the PAS sensitivity as we increased the O 2 fraction in the bath gas, which reached an asymptote near 100 % O 2 that nearly matched the sensitivity measured with both NO 2 and nigrosin particles. We interpret this dependence with a kinetic model that suggests the reason for the observed results is a more efficient transfer of energy from excited O 3 to O 2 than to N 2 by a factor of 22–55 depending on excitation wavelength.

Summary Glucocorticoids are important mediators of energy utilization for key physiological processes, including immune function. Much work has focused on the effects of energy limitation and stress for key physiological processes such as reproduction and immunity. However, it is unclear how stress alters energy use across different energy states, and the physiological ramifications of such effects are even less clear. In this study, we altered energy and stress states of an infrequent feeder, the terrestrial gartersnake (Thamnophis elegans), using fasting and repeated restraint stress (chronic stressors) to test how these challenges interacted to affect immune function, energy metabolites and glucocorticoid reactivity (a traditional indicator of stress state) to restraint stress, a standardized, acute stressor. After this acute stressor, the snakes which had received chronic stress had increased glucocorticoid reactivity, and both treatments altered energy metabolite use and storage. Evidence of interaction of food restriction and chronic stress treatments on innate immune function and energy metabolites (triglycerides and glycerol) suggests that stress alters energy use in a manner dependent on the energy state of the animal. Snakes have a remarkable ability to maintain functionality of key physiological processes under stressful conditions but are still susceptible to multiple simultaneous stressors, a situation increasingly prevalent in our ever-changing environment.

Light-absorbing organic material, or "brown carbon" (BrC), can significantly influence the effect that aerosols have on climate. Here, we investigate how changing pH affects the absorption spectra of water-soluble BrC from ambient particulate matter smaller than 2.5 μm collected in Athens, Georgia, in the spring and fall of 2016, including samples from nearby wildfires. We find that absorption increases 10% per pH unit from pH 2 to pH 12 with a broad, featureless tail at visible wavelengths, where the largest fractional increase is also observed. The resulting change in the spectral shape causes the absorption Ångström exponent to decrease by 0.18 per unit increase in pH. Similar behavior with humic substances suggests that they and BrC share a common link between pH and absorption, which we propose could be a consequence of conformational changes in supramolecular assemblies thought to exist in humic substances. Specifically, we hypothesize that a wider variety and larger number of absorbing charge transfer complexes are formed as functional groups in these molecules, such as carboxylic acid and phenol moieties, become deprotonated. These findings suggest that (1) the pH of ambient particulate matter samples should be measured or controlled and (2) radiative forcing by BrC aerosols could be overestimated if their pH-dependent BrC absorption is not accounted for in models.

We investigated the presence of ectoparasites and hemoparasites in side-blotched lizards (Uta stansburiana) across a large part of their range and measured how parasitic infection related to several key physiological indicators of health. Blood samples were collected from 132 lizards from central Arizona, southern Utah, and eastern Oregon. Hemoparasites were found in 22 individuals (3.2% prevalence in Arizona, 19.1% in Utah, and 6.3% in Oregon), and ectoparasites were found on 51 individuals (56.3% prevalence in Arizona, 56.1% in Utah, and 6.7% in Oregon), with 11 individuals infected with both. Hemoparasites and ectoparasites were found in all three states. Immunocompetence was higher in individuals infected with both hemoparasites and ectoparasites. Body condition, glucocorticoid levels, and reproductive investment were not related to infection status. Our study provides evidence that parasitic infection is associated with an active immune system in wild reptiles but may not impose other costs usually associated with parasites.

It is now recognized that some organic components of ambient aerosols absorb light with a spectrum distinct from that of other absorbers such as black carbon and mineral components. The most common method for isolating this light-absorbing organic fraction, or “brown carbon,” is to collect particulate matter on filters and extract in a solvent, usually water or methanol. Here, we compare the absorption spectra of water-soluble (WS) and methanol-soluble (MS) extracts from ambient samples collected in Athens, Georgia. We find that despite syringe filtering the MS extracts, extinction by suspended particles is evident in the spectra leading to an overestimation of absorption by a factor of two on average. No such particle extinction is evident in the WS extracts. We demonstrate that it is possible to subtract the extinction contribution in the MS extracts by fitting the spectrum to the sum of two power-law functions, one describing the absorption spectrum and the other describing the extinction spectrum. With extinction thus removed, we find that integrated absorption (300–800 nm) by the MS brown carbon extract is highly correlated with the WS extract and is on average 1.55× larger. The wavelength dependence of the WS and MS spectra are also correlated and very similar with average absorption Ångström exponents of 6.1 (±0.7) and 6.7 (±1.1), respectively. This study demonstrates that for the samples collected: (1) brown carbon absorption can be overestimated if scattering in MS spectra is not accounted for, (2) there is no spectral evidence that the WS and MS chromophores are different, and (3) it may be possible to use WS spectra to represent total brown carbon absorption using a simple scaling factor. These findings may differ for other types of aerosol samples and analytical methods. © 2017 American Association for Aerosol Research

The light-absorbing fraction of organic molecules in ambient aerosols, known as "brown carbon," is an important yet poorly characterized component. Despite the fact that brown carbon could alter the radiative forcing of aerosols significantly, identification of specific chromophores has remained challenging. We recently demonstrated that charge transfer (CT) complexes formed in organic molecules could be responsible for a large fraction of absorption observed in water-extracted ambient particulate matter.1 In the present study, we use excitation-emission matrix fluorescence spectroscopy to further corroborate the importance of CT complexes in defining aerosol optical properties. Monotonically increasing and decreasing quantum yields, decreasing Stokes shifts, and red-shifting emission maxima are observed from ambient particulate matter collected in Athens, Georgia, strongly suggesting that a superposition of independent chromophores is not sufficient to explain brown carbon absorption and fluorescence. Instead, we show that a model in which such chromophores are energetically coupled to a dense manifold of CT complexes is consistent with all of the observations. Further, we suggest that a significant fraction of the observed fluorescence originates from CT complexes and that their contribution to brown carbon absorption is likely greater than we reported previously.

Recently, it has become apparent that a fraction of the organic species in ambient aerosols absorbs ultraviolet–visible light with a potential impact on climate. It is believed that this light-absorbing, sometimes called “brown”, carbon originates from biomass and biofuel burning and could be formed through secondary processes in particles or clouds. Here, we identify for the first time charge transfer (CT) complexes as a significant source of light absorption by organic compounds in aerosols. A dense manifold of these complexes, formed from interactions between alcohol and carbonyl moieties, accounts for approximately 50% of the absorption (300–600 nm) observed for water-extracted ambient particulate matter collected in Athens, GA. Corresponding fluorescence emission spectra with broad, overlapping long-wavelength tails are consistent with efficient energy transfer among a near continuum of such coupled excited states. We postulate that a wide variety of CT complexes are formed as a result of a supramole...

Cavity ring-down spectroscopy (CRDS) is a technique that is commonly used to measure the extinction of light by aerosol particles in situ. This extinction, when normalized to particle concentration, yields the extinction cross section, a measure of a single particle's ability to scatter and absorb light. The complex index of refraction can then be retrieved by comparison of the extinction cross sections at several particle diameters with those predicted by Mie theory. This approach requires accurate determination of particle diameter and concentration as well as the length of the extinction region in the cavity, but it is often difficult to quantify the systematic errors in the measurements of these quantities. Here, we introduce a calibration technique using particles of a reference compound to account for these systematic errors. The two calibration parameters are: Cf , which scales the measured extinction cross sections, and Δd, which shifts the particle diameters. It is found that Cf correlates strong...

The energetic cost of immunity depends on many factors, including the type of challenge, the timing of the response, and the state of the animal. We measured changes in the standard metabolic rates of side-blotched lizards (Uta stansburiana Baird and Girard, 1852) in response to different immune challenges and nutritional states. In the first experiment, lizards were randomly assigned to one of four treatments: lipopolysaccharide (LPS) injection (to stimulate the response to a pathogen), cutaneous biopsy (as a proxy to a superficial wound), both injection and biopsy, or neither (control). Four and five days later, we measured the standard metabolic rates of the lizards. In response to healing a cutaneous wound, lizards reduced metabolic rate and lost body mass. Healing rate was also inversely related to weight loss, but LPS had no effect on body mass or metabolic rate. In the second experiment, a new set of lizards were randomly assigned to a high-food or low-food diet and administered a cutaneous biopsy. As in the first experiment, we observed a reduction in metabolic rate after wounding; moreover, this decrease was positively correlated with the rate of healing. We observed higher rates of metabolism in lizards that ate more food, but food consumption was unrelated to the decrease in metabolic rate following the biopsy. These experiments demonstrate the dynamic nature of the immune response in response to immune challenge and the state of the organism.

The gas-phase reactions of NO(3) radicals with series of 1-alkenes, dienes, cycloalkenes, alkenols, and alkenals were studied in pure N(2) or 20% O(2)/80% N(2) bath gas at room temperature and atmospheric pressure using a relative rates technique. Rate coefficients were derived from rates of loss of the organic compounds observed using a chemical ionization mass spectrometer. No difference in the measured kinetic data was observed in the presence or absence of O(2). The rate coefficients obtained (k (10(-13) cm(3) molecule(-1) s(-1)), with uncertainties representing 95% confidence intervals) are as follows: 1-hexene, 0.233 ± 0.021; 1-heptene, 0.245 ± 0.029; 1-octene, 0.292 ± 0.044; 1,3-butadiene, 1.24 ± 0.09; isoprene, 6.24 ± 0.11; 2,3-dimethyl-1,3-butadiene, 14.1 ± 0.5; 1,3-cyclohexadiene, 112 ± 8; cyclopentene, 4.82 ± 0.13; cyclohexene, 5.38 ± 0.20; cycloheptene, 5.28 ± 0.23; 2-buten-1-ol (crotyl alcohol), 3.23 ± 0.12; cis-2-penten-1-ol, 3.11 ± 0.11; cis-2-hexen-1-ol, 3.81 ± 0.38; trans-2-pentenal, 0.193 ± 0.040; trans-2-hexenal, 0.136 ± 0.029; trans-2-heptenal, 0.231 ± 0.036; cis-4-heptenal, 4.03 ± 0.24. The measured rate coefficients are compared to values from previous studies and three structure-activity relationships (SARs), and good agreement is found, in general. In particular, the recently developed SAR of Kerdouci et al. (Kerdouci, J.; Picquet-Varrault, B.; Doussin, J. ChemPhysChem2010, 11, 3909-3920.) is found to estimate the rate coefficients within 35% for all of the measured reactions except for NO(3) + 1,3-butadiene. The SAR prediction for that reaction is nearly 50% lower than the measured value, suggesting that it underestimates the effect of conjugation on the reaction of NO(3) with this small diene. The measured rate coefficients for reactions with a series of alkenols are used to modify the SAR substituent factor for the -CH(2)OH group, and those for reactions with a series of trans-2-alkenals are used to derive a substituent factor for the -C(O)H group, which was not included in the original SAR because of insufficient experimental data.

The reaction kinetics of ozone with oleic acid (OA) in submicron particles containing n-docosane has been studied using aerosol CIMS (chemical ionization mass spectrometry) to monitor changes in particle composition. Internally mixed particles with X(OA)0.72 were found to exist as supercooled droplets when cooled to room temperature. Partial reaction of the oleic acid was seen to completely inhibit further reaction and was attributed to the formation of a metastable solid rotator phase of the n-docosane at the surface. This reaction-induced phase change is believed to prevent further reaction by slowing ozone diffusion into the particle. When these particles were cooled to 0 degrees C before reaction, they reacted to a further extent and did not demonstrate such an inhibition. This shift in reactivity upon cooling is attributed to the formation of the thermodynamically stable form of n-docosane, the triclinic solid. This transition was accompanied by an increase in the n-docosane density, which led to the development of "cracks" through which ozone can diffuse into the particle. The aerosol with X(OA)0.72 consisted of an external mixture of particles containing n-docosane in either the rotator or the triclinic solid phase because of the stochastic nature of the rotator --triclinic transition. The reactivity of the oleic acid was seen to increase with increasing n-docosane content as a larger fraction of the particles underwent the rotator --triclinic transition and therefore contained cracks at the surface. These findings demonstrate the importance of transient, metastable phases in determining particle morphology and how such morphological changes can influence rates of reactions in organic aerosols.

We investigated the effects of temperature on the growth and development of embryonic and early larval stages of a western North American amphibian, the rough-skinned newt (Taricha granulosa). We assigned newt eggs to different temperatures (7, 14, or 21°C); after hatching, we re-assigned the newt larvae into the three different temperatures. Over the course of three to four weeks, we measured total length and developmental stage of the larvae. Our results indicated a strong positive relationship over time between temperature and both length and developmental stage. Importantly, individuals assigned to cooler embryonic temperatures did not achieve the larval sizes of individuals from the warmer embryonic treatments, regardless of larval temperature. Our investigation of growth and development at different temperatures demonstrates carry-over effects and provides a more comprehensive understanding of how organisms respond to temperature changes during early development.

Aerosol chemical ionization mass spectrometry (CIMS) is used both on- and off-line for the analysis of complex laboratory-generated and ambient particles. One of the primary advantages of Aerosol CIMS is the low degree of ion fragmentation, making this technique well suited for investigating the reactivity of complex particles. To demonstrate the usefulness of this “soft” ionization, particles generated from meat cooking were reacted with ozone and the composition was monitored as a function of reaction time. Two distinct kinetic regimes were observed with most of the oleic acid in these particles reacting quickly but with 30% appearing to be trapped in the complex mixture. Additionally, detection limits are measured to be sufficiently low (100–200 ng/m 3 ) to detect some of the more abundant constituents in ambient particles, including sulfate, which is measured in real-time at 1.2 μg/m 3 . To better characterize complex aerosols from a variety of sources, a novel off-line collection method was also developed in which non-volatile and semi-volatile organics are desorbed from particles and concentrated in a cold U-tube. Desorption from the U-tube followed by analysis with Aerosol CIMS revealed significant amounts of nicotine in cigarette smoke and levoglucosan in oak and pine smoke, suggesting that this may be a useful technique for monitoring particle tracer species. Additionally, secondary organic aerosol formed from the reaction of ozone with R-limonene and volatile organics from orange peel were analyzed off-line showing large molecular weight products ( m / z > 300 amu) that may indicate the formation of oligomers. Finally, mass spectra of ambient aerosol collected offline reveal a complex mixture of what appears to be highly processed organics, some of which may contain nitrogen.

The recently developed technique of aerosol chemical ionization mass spectrometry is used to study the reaction of ozone with particles consisting of unsaturated organic molecules, including oleic acid, linoleic acid, oleyl alcohol, and 1-octadecene. The reactive uptake coefficients, γ, for polydisperse aerosols with mean diameters of 800 nm are determined from the rates of loss of the particle species to be (7.5 ± 1.2) × 10-4 for oleic acid, (1.1 ± 0.2) × 10-3 for linoleic acid, (7.5 ± 1.3) × 10-4 for oleyl alcohol, and (2.4 ± 0.4) × 10-4 for 1-octadecene. The ozonolysis products of oleic acid particles are studied in detail with simultaneous detection of the four primary products: nonanal, nonanoic acid, 9-oxononanoic acid, and azelaic acid. All four products are found to exist in the reacted particles, though nonanal is also detected in the gas phase indicating that it partially evaporates. The yield of azelaic acid is determined to be 0.12 ± 0.04, and the yields of nonanal and 9-oxononanoic acid are ...

The calothrixins are quinone-based natural products isolated from Calothrix cyanobacteria which show potent antiproliferative properties against several cancer cell lines. Preliminary mechanistic studies suggest that the biological mode of action of the calothrixins may be linked to their ability to undergo redox cycling. In this study we compare the bioactivities of the calothrixins with those of structurally related quinones in order to identify the structural features in the calothrixins essential for biological activity. In particular, the reduction potentials of the calothrixins and some related quinones were measured electrochemically. Our studies indicate that while there is no direct correlation between the reduction potentials and biological activities of the studied compounds, in all cases quinones with EC(50) values

The cyanobacterium Nostoc strain ATCC 53789, a known cryptophycin producer, was tested for its potential as a source of natural pesticides. The antibacterial, antifungal, insecticidal, nematocidal, and cytotoxic activities of methanolic extracts of the cyanobacterium were evaluated. Among the target organisms, nine fungi ( Armillaria sp., Fusarium oxysporum f. sp. melonis , Penicillium expansum , Phytophthora cambivora , P. cinnamomi , Rhizoctonia solani , Rosellinia , sp., Sclerotinia sclerotiorum , and Verticillium albo-atrum ) were growth inhibited and one insect ( Helicoverpa armigera ) was killed by the extract, as well as the two model organisms for nematocidal ( Caenorhabditis elegans ) and cytotoxic ( Artemia salina ) activity. No antibacterial activity was detected. The antifungal activity against S. sclerotiorum was further studied with both extracts and biomass of the cyanobacterium in a system involving tomato as a host plant. Finally, the herbicidal activity of Nostoc strain ATCC 53789 was evaluated against a grass mixture. To fully exploit the potential of this cyanobacterium in agriculture as a source of pesticides, suitable application methods to overcome its toxicity toward plants and nontarget organisms must be developed.

The reactive uptake of gases by a particle is explored by numerically solving the associated partial differential equations. These equations explicitly couple the diffusion and reaction of multiple species in the particle. This approach makes it possible to calculate the concentration of each reactant within the particle as a function of both time and position and to examine the impact of concentration gradients on the rate of uptake. The effect of liquid diffusion on the rate of uptake is explored for a reference reaction (O3 + oleic acid particles) as a function of the particle size and the liquid-state concentration of the species taken up from the gas phase. Diffusion within the particle is found to significantly limit uptake for large particles and the large gas-phase concentrations often used in laboratory experiments, although it is typically less important under atmospheric conditions. This numerical approach to solving the diffusion−reaction equations is also used to modify the common electric ci...

Calothrixin A is a bioactive metabolite of the cyanobacterium Calothrix and has been shown to be active at nanomolar concentrations against human HeLa cancer cells. It induces apoptotic killing of human Jurkat cancer cells in a time- and concentration-dependent manner, as revealed by flow cytometry, morphological evidence from electron microscopy and DNA fragmentation. It also causes G2/M cell cycle arrest, which is indicative of intracellular DNA damage. It was shown to be redox-active, as measured by oxygen uptake in the presence of dithiothreitol, and caused cleavage of plasmid DNA, as revealed by electrophoresis. This cleavage was blocked by the H2O2 scavenger catalase, but not by other scavengers of reactive oxygen species (ROS). Calothrixin A appeared to induce intracellular formation of ROS as measured by fluorescence of dichlorodihydrofluorescein diacetate. Conditions were not found, however, under which the calothrixin A-induced apoptosis could be reversed by the scavengers, or by the metal chelator desferal. Menadione was compared with calothrixin A. The IC50 at which this compound caused apoptosis was significantly higher. It also induced cell cycle arrest at higher concentrations, although caused plasmid DNA cleavage at lower concentrations. It is postulated that the greater effectiveness of calothrixin A in killing cells is related to its ring structure, which has the characteristics of a DNA intercalator, thereby localizing its quinone-dependent effects.

The technique of single-particle mass spectrometry has been coupled to a reaction flow tube to measure the uptake coefficient, γ, of ozone (O3) by oleic acid (9-octadecenoic acid) aerosol particles. The reaction was followed by monitoring the decrease of oleic acid in the size-selected particles as a function of O3 exposure. The reactive uptake coefficient is found to depend on the size of the particle, with γmeas ranging from (7.3 ± 1.5) × 10-3 to (0.99 ± 0.09) × 10-3 for particles ranging in radius from 680 nm to 2.45 μm. It is suggested that the decrease in γmeas with increasing particle size results from the reaction being limited by the diffusion of oleic acid within the particle, and based on our measurements we estimate the value of γ to be (5.8−9.8) × 10-3 for particles that are not limited by oleic acid diffusion. A reaction model that includes simultaneous diffusion and reaction of both O3 and oleic acid is developed and used to fit the observed rates of reaction. Solutions obtained from this mo...

Single aerosol particles of ethylene glycol and oleic acid are vaporized on a heater at temperatures between 500 and 700 K, and the resulting vapor plume is ionized by a 10.5-eV vacuum ultraviolet (VUV) laser. The mass spectra are compared to those obtained by CO2 laser vaporization followed by VUV laser ionization. The relative intensities of the parent and fragment ion peaks are remarkably similar for the two modes of vaporization. A Maxwell-Boltzmann distribution of speeds accurately describes the dependence of the signal as a function of the VUV laser pulse timing. The signal levels obtained with this design are sufficient to obtain good-quality mass spectra.