Recent Submissions

  • 3T3-L1 adipocytes as a model of Glut4 translocation

    Collin, Aline; Duffy, Lawrence; Coker, Robert; Coker, Melynda Sheri; Drew, Kelly (2021-12)
    Type 2 diabetes (T2D), a lethal disease, reveals an alarming increase of epidemic proportions and, by 2050, an estimated 1 in 3 adults in the US will suffer from it. Persistent and systemic inflammatory and oxidative stress in adipose tissue and skeletal muscle are recognized as key players in the progression of T2D. T2D is characterized by insulin resistance, the inability of cells to respond to standard circulating levels of insulin, resulting in hyperglycemia. In adipocytes and skeletal muscle, glucose uptake, a vital step in blood glucose regulation, predominantly occurs via the glucose transporter 4 (Glut4) in an insulindependent recruitment from a cytosolic vesicle. Under inflammatory stress, these cells have demonstrated a lack of Glut4 presence in the plasma membrane, leading to a lack of glucose transport within these cells. 3T3-L1 murine adipocytes are a key model to study insulin signaling in vitro. Mature adipocytes are converted from fibroblasts in a lengthy process requiring chemical induction. Several inducers have been tested in hopes to shorten the time span required for differentiation. However, the use of different inducers and changes in the differentiation programming could have consequences on the phenotype of the mature adipocytes. For this reason, we sought to evaluate the differences in 3T3-L1 fibroblasts induced with either 3-isobutyl-1-methylxanthine (IBMX), or troglitazone. In addition to pharmaceutical recourse to restore insulin signaling and glucose uptake in cells under inflammatory duress, a dietary approach has been considered. Natural products such as blueberries have been of particular interest due to their health benefit including antioxidant benefits and their ability to modulate biochemical pathways. Wild Alaskan blueberries are of particular interest due to their link to a reduced prevalence of T2D in Alaskan Native populations. Here, we report differences in the phenotype of 3T3-L1 adipocytes based on the inducer of adipogenesis and a lack of increase in plasma membrane Glut4. Our studies demonstrate a higher expression of adipocyte biomarkers in cells treated with troglitazone compared to IBMX, but a higher expression of total Glut4 in cells treated with IBMX compared to troglitazone. In both phenotypes, we note a lack of insulin-induced increase of plasma membrane levels of Glut4 in 3T3-L1 mature adipocytes. Finally, we demonstrate an insulin-like benefit of Alaskan blueberry extracts on plasma membrane Glut4.
  • Age related dementias

    Soltani, Shahab; Duffy, Lawrence K.; Cruz, Bradley K.; Dunlap, Kriya L. (2021-12)
    During the last few decades, the average life expectancy has dramatically increased in the U.S.A. and globally. As a result, the diseases associated with age, such as dementia, significantly impact families, society, and government. Dementia is a broad term describing memory loss, cognitive dysfunctions, and limited social skills caused by many factors such as aging, stroke, and genetic background. Although the primary etiology remains unclear but inflammatory reactions, neurodegeneration, vascular abnormalities play an important role in the progression of these disorders. Therefore, treatment is mainly supportive to relieve the symptoms of dementia and not to cure dementia or slow down its progression. This review discusses the most common disorders that cause dementia, including Alzheimer's disease, vascular dementia, and Parkinson's disease, as well as their symptoms, diagnosis, and treatments. Also covered are the studies that were performed on these disorders and animal models for each disease.
  • Assessment of an Alaskan willow with potential for polychlorinated biphenyl rhizoremediation

    Slater, Heather Ann; Leigh, Mary Beth; O'Hara, Todd; Trainor, Tom; Rasley, Brian (2010-05)
    "Polychlorinated Biphenyls (PCBs) are priority pollutants targeted for remediation efforts in many areas of the world. Rhizoremediation, the use of plants and their associated root microorganisms for the degradation of a pollutant, may be an inexpensive and effective approach to biodegrading PCBs and detoxifying contaminated soils in situ. Two Alaskan native tree species, Salix alaxensis (willow) or Picea glauca (white spruce), were assessed for the ability to stimulate microbial PCB degradation by measuring PCB loss, toxicity and microbial community shifts in soil microcosms following the addition of crushed roots. Incubation of polluted soils with root crushates of S. alaxensis led to significant losses (up to 30% in 180 days) of several PCB congeners, including many of the most toxic congeners, PCB 77, 105 and 169. Soil toxicity, measured using the Microtox assay, also decreased as a result of treatment with willow-roots. Treatment of soils with salicylate, a willow secondary compound hypothesized to promote aromatic pollutant biodegradation, inhibited PCB degradation, suggesting that other willow biodegradation are responsible for biostimulation. The disappearance of PCB congeners, detoxification of soil, and detection of microbes with PCB degrading abilities suggests that S. alaxensis is a promising plant candidate for rhizoremediation of PCBs"--Leaf iii
  • Design, function, and applicability of a new multiple axis-differential optical absorption spectrometer for observing halogen chemistry in the Arctic

    Carlson, Daniel A. (2010-05)
    "Every springtime reactive halogen species (e.g. bromine atoms and bromine monoxide radicals, BrO) are photochemically released into the Arctic atmosphere by heterogeneous reactions on snow/ice surfaces. These halogens subsequently alter the chemical pathways of the atmosphere by depleting ozone levels to near zero, taking over as the primary oxidizer. An autocatalytic chemical mechanism for the release of reactive halogens from ice surfaces has been described; however, the environmental conditions that lead to halogen production are still unclear, limiting our ability to understand and predict these halogen chemical events. This thesis describes the design and operation of a new autonomous multiple axis-differential optical absorption spectrometer (MAX-DOAS) instrument, which is capable of long term data collection at remote unmanned locations. Novel design features include frost detection and removal, instrumental tilt correction, an enclosed optical scan head, robust data acquisition software, satellite communications compatibility, and low power consumption (~3 Watts). Laboratory and field tests demonstrate that this new instrument is capable of producing high quality BrO measurements. This instrument holds great promise for furthering our understanding of reactive halogens in the polar regions, in particular through investigations of environmental conditions leading to halogen release as well as by validating and improving satellite methods"--Leaf iii
  • Dissolution and sorption of hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine and 2, 4, 6-trinitrotoluene residues from detonated phyllosilicate mineral surfaces

    Jaramillo, Ashley Marie (2010-08)
    "Military training and testing exercises using explosive ordnances has resulted in training range surface soil becoming contaminated with high explosive (HE) residues. Composition B (Comp B) is a commonly used military formulation composed of 2, 4, 6-trinitrotoluene (TNT) and hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX), two toxic HE materials. The potential risk of human exposure to these compounds and the efficacy of remediation efforts depend on the fate and transport of each compound in the environment. Numerous investigations of the temporal fate of HE compounds in soil materials have been conducted, however, most of these studies relied on the application of HEs to soils through aqueous addition. The purpose of this study is to investigate the dissolution and sorption of TNT and RDX originating from Comp B residues loaded to pure mineral phase surfaces through detonation. Detonation caused the heterogeneous loading of TNT and RDX onto each mineral substrate surface. Composition B residues dissolved rapidly (within 9 hours) for all samples, but maximum concentrations for either compound were not sustained due to precipitation from solution and/or sorption onto each mineral substrate surface"--Leaf iii
  • Assessment of fungal and bacterial bioaerosols in ambient air in Fairbanks, Alaska

    Patil, Mitali S.; Cahill, Catherine; Leigh, Mary Beth; Kuhn, Thomas (2011-12)
    Bioaerosols are solid or liquid particles of biological origin that are suspended in the surrounding air or other gaseous environments. Bioaerosols can cause diseases, allergenic or toxicological reactions, respiratory distress, and can be potential bioterrorism threats. Studies concerning ambient bioaerosols have never focused upon central Alaska, and only one experiment has utilized the DRUM (Davis Rotating Unit for Monitoring) impactor as the collection apparatus. This study focuses on the assessment and identification of fungi and bacteria present in the ambient air collected by the DRUM impactor from March 2008 to January 2009. The samples were collected on MylarTM and aluminum substrates (with or without apiezon coating) and subjected to DNA extraction and nested PCR using universal primers for the 16S rRNA gene in bacteria and ITS (internal transcribed spacer) region in fungi. The PCR products were used to generate a clone library, and selected clones from each sample clone library were sequenced. Sequences were taxonomically classified using BLAST for fungal identification and RDP Pipeline for bacterial identification to the genus level. Numerous species of bacteria (i.e., Ralstonia sp., Bradyrhizobium sp., Sphingomonas sp.) and fungi (i.e. Fusarium sp., Cladosporium sp., Penicillium sp.) were identified from the clone libraries, thus indicating that the DRUM impactor has potential for monitoring biological content in the air. The resulting patterns in bacteria and fungi during the course of the year indicate that the DRUM sampler may also have the potential to detect fluctuations in populations that result from meteorological conditions, seasonal cycles, and climatic conditions.
  • Tropospheric reactive bromine and meteorology over the Arctic Ocean

    Swanson, William; Simpson, William; Guerard, Jennifer; Trainor, Thomas; Mao, Jingqiu (2021-08)
    During late winter and spring in the Arctic, unique chemistry produces high levels of reactive bromine radicals (e.g., bromine atomic radicals and bromine monoxide, BrO) in the lower troposphere. These high levels of bromine radicals react with and reduce ambient ozone and oxidize gaseous elemental mercury. These reactive bromine species are chemically released from frozen saline surfaces and are affected by meteorological processes such as transport and mixing. Prior work has proposed that heterogenous reactions on snowpack surfaces as well as on atmospheric particle surfaces contribute to the reactive bromine production. We investigate these hypotheses using an extensive dataset of lower-tropospheric BrO observations from the Arctic Ocean and Utqiaġvik (formerly Barrow). First, we combine BrO observations with meteorological data and use principal component analysis to determine what environmental processes are correlated with BrO. We find that increased levels of reactive bromine under two sets of meteorological conditions: 1) stable, poorly vertically mixed conditions with temperature inversions, and 2) low-atmospheric-pressure conditions with increased vertical mixing. A principal component regression model based on these correlations predicted both the vertical column density of BrO in the lowest 2 km of the troposphere (R = 0.45) and the vertical column density of BrO in the lowest 200 m (R = 0.54). Next, we compare BrO observations to a global chemicaltransport model, GEOS-Chem, which was recently modified to add a blowing snow sea salt aerosol particle source. The GEOS-Chem model including the blowing snow process predicts monthly averaged BrO within experimental error for 9 of 13 total months of observations in Spring 2015 but cannot replicate hourly peaks in observed BrO. The model also predicts BrO during the Fall, which is not supported by the observations, potentially indicating a problem with the blowing snow model. We improve GEOS-Chem by adding a snowpack source of molecular bromine arising from deposition of precursor species such as ozone. Adding this snowpack molecular bromine source improves the agreement between the model and the observed monthly BrO at Utqiaġvik. However, a prior literature form of this model that had assumed an increased daytime yield of molecular bromine due to photochemistry leads to overprediction of radical bromine and is not supported. We find that using both the blowing snow aerosol particle source and the snowpack molecular bromine source together in GEOS-Chem increases model skill in simulating Arctic reactive bromine events. Our global chemical model improvements should improve prediction of the effect of climate change on Arctic reactive bromine levels and help assess their implications for ozone depletion and mercury deposition.
  • Vetting model and satellite-based estimates of regional scale carbon exchange at northern high latitudes using solar-viewing infrared spectroscopy

    Jacobs, Nicole; Simpson, William R.; Euskirchen, Eugénie S.; Guerard, Jennifer; Maxwell, David A. (2021-08)
    Carbon exchange in the Boreal Forest and its response to a warming climate is a critical process that needs to be understood for more accurate predictions of climate change. Therefore, we established a ground-based long-term monitoring site at the University of Alaska Fairbanks in Fairbanks, Alaska, USA (64.859°N, 147.850°W) operating a solar-viewing Bruker EM27/SUN Fourier transform infrared spectrometer (FTS). This instrument measures vertically integrated column abundances of carbon dioxide (CO₂), methane (CH₄), and carbon monoxide (CO), termed Xgas, i.e., XCO₂. These measurements are directly comparable to satellite-based measurements, for which these ground-based observations provide validation data. Measurements of XCO₂ and XCH₄ have to be extremely precise because variability in atmospheric columns of CO₂ and CH₄ is often less than 1% of the background levels of these long-lived gases. Therefore, the observations in Fairbanks were carefully vetted through comparisons of results from two retrieval algorithms applied to the same observed spectra, comparisons of observations from two EM27/SUN FTS operating side-byside, and comparisons between an EM27/SUN FTS and measurements from a Bruker IFS125HR in the Total Carbon Column Observing Network (TCCON) at Caltech, Pasadena, California. These data are all collected over a period of about 4.5 years. Comparisons of retrieval methods indicate that the results are tightly correlated, but there are offsets that could be corrected with an appropriate scaling factor. Observed biases between two colocated EM27/SUN FTS were in agreement within instrument precision. Biases between the EM27/SUN and TCCON retrievals at Caltech are larger and more variable than biases between the two EM27/SUN FTS in Fairbanks, which may be partially explained by differences in spectral resolution. These biases are also similar to those reported in previous studies. Vetted Fairbanks observations are used in combination with those from two TCCON sites in the Boreal Forest, East Trout Lake, Saskatchewan, Canada (54.354°N, 104.987°W) and Sodankylä, Finland (67.367°N, 26.631°E), to evaluate quality control methods and bias in XCO₂ from the NASA Orbiting Carbon Observatory 2 (OCO-2). This study yielded alternative quality control thresholds and bias correction, tailored to Boreal Forest regions that allow for increased data throughput and reduced seasonality in bias over northern high latitude regions. In particular, increased data throughput in spring and autumn months made it possible to measure XCO₂ seasonal cycles using satellite-based measurements. In this analysis, we found that the Asian Boreal Forest region stood out as having the largest seasonal amplitude and earliest seasonal drawdown of any region. There is also a pronounced west-to-east gradient of increasing seasonal amplitude and earlier seasonal drawdown across the Eurasian continent. Comparisons with two independent global CO₂ models are good, showing high correlation and spatial agreement. Analysis of modeled (GEOS-Chem) surface contact tracer contributions reveals that the largest seasonal amplitudes occur in regions that have the largest contributions from land-based surface contact tracers with 15 or 30 day atmospheric lifetimes, suggesting that accumulations of CO₂ exchanges during atmospheric transport on approximately monthly timescales play an important role in shaping observed XCO₂ seasonal cycles in northern high latitude regions. Furthermore, surface contact tracer contributions from land were more correlated with XCO₂ seasonal amplitude than estimates of total annual fluxes or seasonal amplitudes of flux estimates within a region, emphasizing the importance of understanding the effects of atmospheric transport when interpreting observations of XCO₂.
  • Enhancing tumor antigen presentation with complement targeted liposomes

    Francian, Alexandra; Kullberg, Max; Kuhn, Thomas; Burkhead, Jason; Knall, Cindy (2021-08)
    Tumor-mediated immune evasion and suppression can be prohibitive to successful cancer treatment and recovery. A defining trait of cancer progression is when tumor cells develop the ability to evade detection by the immune system. Advanced tumors can suppress the presentation of antigens to effector immune cells by secreting regulatory cytokines and by downregulating the expression of major histocompatibility complex I (MHC I) receptors on the surface of tumor cells. Effective anti-tumor immunity requires the processing and persistent presentation of tumor antigens to effector cells. The cells responsible for this are antigen presenting cells (APCs), which initiate the immune response against cancer by engulfing and presenting tumor antigens to effector immune cells. APCs present tumor antigens, which provide specific targets for helper T cells and cytotoxic T lymphocytes, allowing the immune system to distinguish cancer cells from noncancerous cells. There are many different types of tumor antigens, and the increased effort to sequence reactive epitopes and establish a database makes tumor antigen immunotherapy a promising avenue for treatments and vaccines. Immunotherapies have been developed to restore the immune response against tumors without the toxic side effects of chemotherapeutic drugs. This research describes a promising cancer immunotherapy utilizing a liposome nanoparticle that binds to endogenous complement C3 proteins in serum and is internalized by APCs through the complement C3 receptor, resulting in direct delivery of encapsulated compounds. APCs were shown to internalize C3-bound liposomes containing ovalbumin (OVA), a model antigen, resulting in a significant increase in activated T cells that recognize OVA, reduced tumor growth in all mice (n=5), and complete elimination of both treated and distal tumors in two out of five mice (40%). Blood from treated mice had lower percentages of immunosuppressive cells, higher percentages of B cells, and increased anti-OVA IgG1. Collectively, treatment with OVA C3-liposomes is able to induce the activation of both cell-mediated and humoral immune responses. C3-liposomes encapsulating a melanoma tumor antigen, TRP-2, were able to reduce and eliminate established tumors in a melanoma tumor model in 6 out 7 mice (86%), with the addition of checkpoint blockade, anti-CTLA-4, improving the results (tumor reduction in all mice; n=3). C3-liposomes were also able to induce expression of costimulatory molecules and the production of proinflammatory cytokines and factors in targeted APCs. These results indicate that C3-liposome delivery of tumor antigens to APCs initiates a potent and systemic antitumor immune response.
  • A sled dog model for positive health effects of weight management and exercise

    Falkenstein, Laura Kay; Dunlap, Kriya; Coker, Robert; Jerome, Scott (2021-08)
    Hypertrophic white adipose tissue found in obesity leads to chronic inflammation and reduced insulin sensitivity, bringing rise to a myriad of diseases and is a significant risk factor for premature death. Obesity can be combatted with physical activity, dietary restrictions, or a combination of the two. However, exercise training regardless of changes in body weight has been shown to improve metabolic health. Expanding on a previous study of changes in metabolic biomarkers upon weight gain and after a period of athletic conditioning, in this project we used a sled dog model to examine biomarker shifts over a course of sedentary weight gain, exercise training without weight loss, and exercise training accompanied by weight loss. In order to examine the benefits of exercise training both with and without weight loss, a cohort of healthy sled dogs each served as their own controls as we observed changes in metabolic indices in conjunction with moderate body weight gain, exercise training while sustaining the higher body weight, and exercise training with weight loss.We focused on indices specifically linked to type II diabetes - an obesity-linked disease affecting more than 10% of American adults. Biomarkers measured include plasma glucose, glucose transporter 4, insulin, and hemoglobin A1c. We also measured inflammatory cytokines tumor necrosis factor alpha and interleukin 6, as well as hormones leptin, adiponectin, and resistin. Many biomarkers measured produced not significant change or fell outside of our standard concentrations, but plasma glucose, glucose transporter 4, and tumor necrosis factor alpha produced intriguing results. Weight gain increased plasma glucose while exercise training increased glucose transporter 4 present on peripheral blood mononuclear cells. The changes we observed to plasma glucose, glucose transporter 4 and tumor necrosis factor alpha may be indicative of reduced insulin sensitivity with exercise and weight loss. We believe this may be the result of the high energy demand of exercise training coupled with low caloric availability.
  • Sled dogs as a model for studying dietary vitamin D

    Striker, Kali; Dunlap, Kriya; Jerome, Scott; Drew, Kelly (2021-05)
    Vitamin D deficiency (VDD) has become a pandemic and has shown to be correlated with several poor health outcomes. Many factors that lead to VDD are environmental and lifestyle. Vitamin D has physiological implications involved in all areas of human health and is also important for animal health. Canines have shown adverse health outcomes similar to humans that correlate with vitamin D deficiency such as chronic kidney disease (CKD) and irritable bowel disease (IBD). Canine vitamin D requirements are largely unknown due to the lack of research and the wide ranges of supplementation throughout dog food manufacturers. Pre-active plasma vitamin D metabolites are used as the biomarker of vitamin D status in humans and dogs but may not be representative of overall vitamin D status. Therefore, other biomarkers representing vitamin D status are often used in conjunction to determine physiological relevance. To address this gap in knowledge, this study used parathyroid hormone concentrations as well as vitamin D binding protein concentrations to establish more of an overall status of vitamin D. In canines, clinical supplementation following VDD is usually administered orally with vitamin D olive oil tablets; however, supplementation is usually unsuccessful. Vitamin D and its metabolites are lipid soluble and stored in adipose tissue. Although few foods provide appreciable levels of vitamin D, wild salmon contain some of the highest dietary vitamin D levels. People living in Alaska are at an increased risk of VDD due to reduced zenith sun angles for much of the year. Consequentially sufficient vitamin D levels need to be acquired through diet or supplementation. Historically, Alaska Natives obtained sufficient amounts of vitamin D from traditional subsistence foods, but with the progressive shift away from these foods VDD has increased in Alaskan populations. The limited research available suggests that Alaskan sled dogs in particular are a group found to be generally VDD. Sled dogs are an important part of the traditional Alaska subsistence lifestyle and have evolved alongside humans in the circumpolar north. Sled dogs, therefore, provide a valuable model for studying health outcomes associated with VDD in both people and dogs in the far north. This study provides significant evidence showing wild Alaskan salmon as a dietary source of supplementation to raise 25(OH)Vitamin D serum in dogs after only 4 weeks. We also show significance in variation by confounding factors, age and sex.
  • Photosensitized degradation of chlorothalonil and chlorpyrifos in the presence of Arctic derived dissolved organic matter

    Quesada, Ginna; Guerard, Jennifer; Rasley, Brian; Green, Thomas (2021-05)
    Pesticides used at mid latitudes can accumulate in Arctic environments. Two commonly detected pesticides in Arctic lakes are chlorothalonil and chlorpyrifos. In surface waters, photolysis can play an important role in the attenuation of contaminants. The chemical characteristics of dissolved organic matter (DOM) can further alter the extent of photolytic degradation of pollutants. To determine the relative effect of natural Arctic lake water and its DOM on the photolysis of chlorpyrifos, experiments were conducted under natural Arctic irradiation and under artificial irradiation. Similarly, the effect of Arctic DOM was investigated for chlorothalonil under artificial irradiation. The fulvic acid (FA) fraction of DOM was isolated from Fog 1 and from Toolik Lake in May and July. Lake waters significantly enhanced the photodegradation of chlorpyrifos under natural light by up to an order of magnitude. FA's significantly increased the degradation of chlorpyrifos (>2x) and chlorothalonil (>100x) under artificial irradiation relative to 18 MΩ-cm Water. Toolik Lake FA isolated in May, significantly enhanced the photolysis of both contaminants relative to the isolate collected in July. In the presence of iron, a lower ratio of carbohydrates and peptides to aromatics in the FA's was associated with faster degradation for chlorothalonil.
  • Characterization of water-soluble brown carbon (WS-BrC) from boreal forest wildfires in the summer season at northern high latitudes

    Banerji, Sujai; Mao, Jingqiu; Simpson, William R.; Guerard, Jennifer J. (2021-05)
    In the current study, we quantify the absorption Ångström exponent (AAE) and the mass absorption coefficient (MAC) of water-soluble brown carbon (WS-BrC) from boreal forest wildfires. We deployed a Particle into Liquid Sampler (PILS) - Liquid Waveguide Capillary Cell (LWCC)-Total Organic Carbon analyzer (TOC) system in downtown Fairbanks during the summer of 2019, to measure the light absorption by WS-BrC between around 200 nm to around 800 nm wavelength range every four minutes, and the concentration of the water-soluble organic carbon (WSOC), every two minutes. We then compute the AAE and MAC to examine the optical properties of brown carbon from boreal forest fires. During this period, several forest fires burned and we sampled particles from these fires. We explored a number of quantitative methods to compute the AAE and find that using the entire wavelength range of 300 nm to 350 nm appears to best represent the wavelength dependence of BrC absorption, in contrast to using just a pair of two wavelengths. The calculated AAE is observed to be ~3 for smaller wildfires and above ~3 for medium and large wildfires, whereas the calculated AAEnew is observed to be ~5 during the sampling of small, medium and large wildfires. The calculated MAC at 365 nm (MAC₃₆₅) tends to be ~1.0 m² g⁻¹ and remains relatively constant during wildfire events. We further compare these values to measurements reported from mid-latitude wildfires, to quantify the difference between the wildfires in Alaska and Canada from that of the wildfires in the contiguous U.S.
  • Metabolite influence on the hibernating Arctic ground squirrel

    Rice, Sarah A.; Drew, Kelly; Kuhn, Thomas; Coker, Robert; Ritter, Robert (2020-12)
    Hibernation is a state of extreme metabolic plasticity and fasting. How hibernators maintain nitrogen homeostasis and regulate amino acid metabolism and how those metabolites influence hibernation physiology remains unknown. We first utilized three approaches to understand nitrogen homeostasis and amino acid metabolism in hibernation: longitudinal metabolic profiling within individual animals over undisturbed torpor, in vivo amino acid isotope tracing in deep torpor, and ¹⁵N isotope tracing in vivo during arousal from hibernation in Arctic Ground Squirrels (AGS). We observed that in vivo whole body production (WBP) of metabolites in deep torpor are profoundly and selectively suppressed in deep torpor. Metabolic profiling over undisturbed torpor bouts shows amino acids with nitrogenous side chains accumulate over torpor while urea cycle intermediates remain unchanged. During arousal from hibernation, ¹⁵N isotope tracing demonstrates recycling of free nitrogen into non-essential amino acids, essential amino acids and the gamma-glutamyl system. We next utilized two approaches to understand potential metabolite influences on thermogenesis and behavior in hibernation: we infused ammonium acetate in deep torpor and fed diets high in omega 3 fatty acids and monitored body temperature and torpor bout length. We found high doses of a nitrogen donor, ammonium acetate, as well as diets high in omega 3 fatty acids both influence thermogenesis in hibernation. In conclusion, production of metabolites in deep torpor indicate highly regulated metabolism with accumulation of nitrogen carrying amino acids. We additionally show metabolites and nitrogen can exert thermogenic influence on hibernating AGS.
  • Assessing adverse effects of mercury in two pinniped species

    Lian, Marianne; O'Hara, Todd M.; Rea, Lorrie D.; Kuhn, Thomas B.; Van Wijngaarden, Edwin (2020-08)
    This dissertation studies measures of adverse effects in free-ranging pinnipeds associated with relatively high total mercury ([THg]) or monomethylmercury ([MeHg+]) concentrations, relatively low total selenium ([TSe]) concentrations and/or low TSe:THg molar ratios. Both the Steller sea lion (SSL, Eumetopias jubatus) and Pacific harbor seal (HS, Phoca vitulina richardii) inhabit coasts of the North Pacific, and are considered important sentinel species for One Health (environmental, animal and human health). Relatively high [THg] is reported for some animals in both species, causing concern for adverse effects especially in the developing fetus. Maternal piscivorous diet can expose the fetus to MeHg⁺ at a vulnerable developmental stage, with potential for adverse effects on several organ systems. This dissertation focused on two of these: nervous system development and function and oxidant/antioxidant homeostasis. In Chapter 2 I outlined capture and field anesthesia of free-ranging SSL. I found faster induction times for sevoflurane over isoflurane, with a significant interaction for anesthetist. Difference among the two agents is most likely attributed to the different chemical properties for these gases (blood solubility), whereas personal experience/comfort level most likely explains the differences between the human operators. Severe hypothermia was also documented, associated with the time of year, sex and duration of anesthetic event. There was an overall low mortality rate, and the protocols were effective for relatively safe field anesthesia of a large mammal. Chapter 3 assessed oxidant/antioxidant status and associations with [THg], [MeHg⁺], [TSe] and TSe:THg molar ratio in anesthetized free-ranging SSL pups. The anesthesia protocols described in Chapter 2 were used as a physiological stressor for measuring oxidative stress in SSL. Pinnipeds as diving mammals are naturally adapted with high antioxidant activity to survive long breath-holds during foraging. However, the relatively high [THg] found in some SSL cause concern for sequestration of Se due to its high binding affinity to Hg, and subsequently decreased antioxidant capacity (Se-dependent glutathione peroxidase (GPx)). I found a significant negative relationship between lipid peroxidation and [TSe], suggesting the potential for decreased antioxidant protection from Se. There were also significant associations between increased GPx activity and lipid peroxidation, possibly protecting pups with relatively high [THg] and low TSe:THg molar ratios. In Chapter 4 I repeatedly evaluated live-stranded HS pups admitted to The Marine Mammal Center, using weekly clinical and behavior assessments, which were analyzed for associations with [THg]. There was a significant association between [THg] in hair and/or blood and decreased response to tactile stimulation, less movement and longer stays in rehabilitation. These findings will help us better assess similar [THg] in hair and blood of SSL in Alaska that we currently study as well as other pinnipeds. In summary, this dissertation confirms the potential for adverse effects in two free-ranging species of pinnipeds exposed to MeHg⁺ in utero.
  • Fate and effects of commercial crude oil bioremediation products in Arctic seawater

    Gofstein, Taylor R.; Leigh, Mary Beth; Simpson, William; Guerard, Jennifer; Collins, R. Eric (2020-08)
    With increased oil exploration, development, and transport in the Arctic in recent years, the potential for disastrous oil spills is imminent. Biodegradation, the consumption of contaminants by indigenous microorganisms capable of using them as an energy source, can be enhanced using bioremediation treatments and may be a viable spill remediation method when traditional physical recovery techniques are not. The EPA National Contingency Plan (NCP) product schedule lists oil spill response treatments that can be used in the event of a spill, many of which can stimulate intrinsic biodegradation. However, there is often little to no experimental data demonstrating the effectiveness of these products in aiding the remediation of a spill. Here we investigate the effects of the currently listed NCP products Corexit 9500 and Oil Spill Eater II (OSEII) on crude oil biodegradation in Arctic seawater and the associated shifts in the microbial community using mesocosm incubations. Despite conflicting reports in the literature, Corexit 9500 showed no inhibitory effects on the biodegradation of crude oil. When oil and Corexit were co-present, chemical and microbial data revealed a sequential degradation beginning with the non-ionic surfactant components of Corexit (Span 80, Tween 80, Tween 85), followed by the degradation of the labile alkane oil components, with the degradation of other Corexit components such as dioctyl sodium sulfosuccinate (DOSS) and dipropylene glycol n-butyl ether (DGBE) less clear. 16S rRNA gene sequencing revealed that oil and Corexit stimulate different microbial communities but some taxa are stimulated by either (Oleispira, Pseudofulvibacter, Roseobacter), suggesting that these organisms may be capable of degrading both. Further analysis with metatranscriptomic sequencing showed increased gene expression in the presence of Corexit, even when co-present with oil, suggesting that Corexit may enhance the metabolic activity of oil degraders. Increased expression of β-oxidation pathway genes (fadE, fadA, fadB) in the presence of Corexit coincided with the chemical loss of Corexit components. Based on these findings and the abundance of ester groups in the chemical structures of Corexit 9500 surfactant components, we propose a biodegradation pathway that involves the transformation of ester groups into fatty acids either through biotic lipase enzymes or abiotic hydrolysis, before funneling into the β-oxidation fatty acid degradation pathway. Taxonomic origins for these transcripts showed a diverse number of genera expressing these genes, which along with its lability may serve to explain the number of taxa observed to respond to Corexit both here and in the literature. Characterization of the contents of OSEII revealed the presence of sugars, surfactants, nutrients, phytochemicals, amylase, protease, and the non-hydrocarbonoclastic non-viable microorganisms Lactobacillus and Saccharomyces. Incubation experiments targeting the efficacy of OSEII showed a slight enhancement of n-alkane loss at 30 days, suggesting that it may have utility in longer term use following a post-spill nutrient depletion. However, the nutrient contents of OSEII were up to 32-fold times higher for ammonia and 100,000-fold times higher for iron than in ambient Arctic seawater, which although are limiting nutrients in seawater, may also cause more harmful ecological effects following a spill by inducing phytoplankton blooms. Based on these findings, the non-ionic surfactants of Corexit 9500 appear to be easily degraded through the proposed β-oxidation fatty acid pathway. Future NCP dispersants should target these labile ester chemical moieties while also being effective at dispersion. It is imperative for NCP products to undergo more rigorous third-party experiments to demonstrate their suitability, effectiveness, toxicity, and unintended side effects that may occur in situ before an oil spill occurs. Doing so will allow decision-makers to have comprehensive information to aid in selection of appropriate oil spill response techniques.
  • The fate of nitrogen pollution in high-latitude winter: investigations using a 1-D photochemical model

    Joyce, Patrick L. (2011-12)
    Simulations using a 1-D photochemical model were performed to analyze the fate of NOx pollution in a high-latitude winter environment. Modeled pollution emissions were constrained by observations from downtown Fairbanks and the model reproduced dilution of NOx on timescales in agreement with field measurements on the edge and outside of the urban area of Fairbanks. The model was updated from previous versions to include calculations of reactions of N₂O₅ on aerosol particles and an empirically-derived value for dry deposition velocity of N₂O₅ to the snowpack, which acts as a competing loss of N₂O₅. It was found that dry deposition of N₂O₅ causes a significant fraction of N₂O₅ loss near the snowpack, but reactions on aerosol particles dominate loss of N₂O₅ over the total atmospheric column. Sensitivity experiment results indicate a strong sensitivity to urban area density (affecting NO flux), season and clouds (affecting photolysis), and weather and climate (affecting temperature), implying a strong sensitivity of the results to urban planning and climate change. Model simulations produced large amounts of secondary ammonium nitrate downwind of the polluted area due to NOx oxidation and subsequent reactions with ammonia on aerosol particles.
  • Mobility and chemical fate of antimony and arsenic in historic mining environments of Kantishna Hills, Denali National Park and Preserve, Alaska

    Ritchie, Vanessa J. (2011-05)
    Oxidative weathering processes of acid-forming sulfide minerals, such as pyrite (FeS₂), and associated arsenopyrite (FeAsS) and stibnite (Sb₂S₃), can have a significant impact on water quality associated with current and legacy mining operations. Concentrations of toxic metals and metalloids, such as antimony (Sb) and arsenic (As), in acid mine drainage can exceed drinking water quality standards by orders of magnitude. This study provides a detailed hydrogeochemical assessment of the mobility and chemical fate of antimony and arsenic in streams draining from historic antimony mines within Denali National Park and Preserve, Alaska. Antimony and arsenic concentrations in stream water reach up to 720 parts per billion (ppb) and 239 ppb, respectively. Aqueous phase antimony and arsenic speciation was determined using liquid chromatography coupled to an inductively coupled plasma mass spectrometer. Antimony in all water samples is predominantly found as Sb⁵ whereas arsenic was detected as mixtures of As³ /As⁵⁺ . Elevated antimony concentrations extend over 8 km downstream from the source, whereas arsenic quickly attenuates within 1.5 km. High correlation between antimony/arsenic and iron concentrations in fine-fraction streambed sediment indicates that sorption and (co)precipitation with iron (hydr)oxides is an important pathway for the attenuation of antimony and arsenic in natural waters.
  • The molecular basis of aerobic metabolic remodeling in threespine stickleback in response to cold acclimation

    Orczewska, Julieanna Inez (2011-05)
    Increases in mitochondrial density during cold acclimation have been documented in many fish species, however the mechanism regulating this process is not understood. The present study sought to characterize metabolic changes in response to cold acclimation and identify how these changes are regulated in oxidative muscle, glycolytic muscle and liver tissue of threespine stickleback, Gasterosteus aculeatus. Fish were warm (20°C) or cold (8°C) acclimated for 9 weeks and harvested during acclimation. Mitochondrial volume density was quantified using transmission electron microscopy and aerobic metabolic capacity assessed by measuring the maximal activity of citrate synthase and cytochrome c oxidase. The molecular mechanism mediating changes in aerobic metabolic capacity were assessed by quantifying transcript levels of aerobic metabolic genes and known regulators of mammalian mitochondrial biogenesis using quantitative real-time PCR. Our results indicate that while the maximal activity of aerobic metabolic enzymes increased in all tissues, mitochondrial biogenesis only occurred in oxidative muscle. Our results also suggest that the time course of metabolic remodeling is tissue specific. Lastly, we identified differences in the magnitude and timing of transcriptional and co-transcriptional activators driving metabolic remodeling between each tissue. These results suggest aerobic metabolic remodeling may be triggered by different stimuli in different tissues.
  • Separation, identification, and quantification of low molecular weight nitrogen containing compounds in fish byproducts

    Nigg, Jonathan; Rasley, Brian; Bechtel, Peter J.; Green, Thomas K. (2011-08)
    There is interest by the fish processing industry in the identification and eventual extraction of higher valued low molecular weight nitrogen compounds from fish byproducts such as stickwater, hydrolysates, fish tissues, and other byproducts. A hydrophilic interaction liquid chromatography (HILIC) method was developed for the separation and quantification of amino acids, small nitrogenous acids and bases, as well as, other nitrogen containing metabolites. The HILIC method developed is a robust and non-derivatizing method for the analyses of aqueous compounds found in freeze dried red salmon whole fish and red salmon byproducts (pretreated stickwater, post-treated stickwater, and fishmeal). Triplicate samples of all byproducts were obtained from commercial processors in Kodiak, AK. Byproduct samples were extracted and centrifugally filtered through 3000 MW membranes. The identification of low molecular weight compounds in different fractions of fish byproduct showed the partitioning of unbound components during fishmeal processing. Several aqueous nitrogen containing compounds were quantified and comparisons were made of these components in different fish byproduct fractions. This study suggests that creative, creatinine, taurine, and hypoxanthine are found in elevated concentrations in stickwater and are preferentially partitioned into the stickwater fraction.

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