Recent Submissions

  • 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.
  • Role of neurotropism in HIV-1 gp120 induced oxidative stress and neurodegeneration

    Smith, Lisa K.; Kuhn, Thomas; Kullberg, Max; Dunlap, Kriya; Chen, Jack (2020-05)
    An estimated 50% of individuals with long-term HIV infection are affected by the onset of progressive neurological and cognitive complications referred to as HIV-associated neurocognitive disorders (HAND). While the molecular mechanisms underlying pathology in HAND remain poorly understood, synaptodendritic damage has emerged as a hallmark of HIV infection of the CNS. This damage is likely mediated by a combination of indirect mechanisms involving the release of inflammatory mediators and viral proteins from infected glial cells, and direct effects mediated by the interaction of neurotoxic viral proteins with neuronal receptors. The neurotoxic HIV envelope glycoprotein gp120 interacts with neuronal receptors CCR5 and CXCR4 to induce the coalescence of lipid raft domains into large, stable platforms-- a proposed mechanism for clustering components of receptor-activated signaling cascades. The interaction of proteins with lipid-raft localized receptors as a mechanism of regulating pathologic signaling has been observed in other neurodegenerative diseases, most notably in Alzheimer's disease, where amyloid- (Aß) oligomers interact with lipid raft-anchored cellular prion protein PrPC to activate a pathway leading to the formation of cofilin-actin rods-like inclusions (rods) in neuronal processes. Rods have been linked to synaptic dysfunction via sequestration of cofilin and the disruption of vesicular transport resulting from the occlusion of neurites in which they form. Given similarities in neuronal response to gp120 and Aß, we sought to assess the ability of gp120 to induce rods. Here, we report viral envelope protein gp120 induces the formation of cofilin-actin rods in E16 mouse hippocampal neurons via a signaling pathway common to oligomeric, soluble amyloid-ß and inflammatory cytokines. Our studies demonstrate gp120 binding to either chemokine co-receptor CCR5 or CXCR4 is capable of inducing rod formation and signaling through this pathway requires the NADPH oxidase-mediated formation of superoxide (O2-) and the expression of cellular prion protein (PrPC). These results link gp120-mediated oxidative stress formation to the generation rods in a previously undescribed mechanism of early synaptic dysfunction observed in HAND.
  • Biophysical characterization of class II major histocompatibility complex (MHCII) molecules

    Osan, Jaspreet Kaur; Ferrante, Andrea; Kuhn, Thomas; Podlutsky, Andrej; Chen, Jack (2020-05)
    Class II Major Histocompatibility Complex (MHCII) molecules are transmembrane glycoproteins expressed on the surface of antigen-presenting cells (APCs). APCs engulf pathogens and digest pathogenic proteins into peptides, which are loaded onto MHCII in the MHCII compartment (MIIC) to form peptide-MHCII complexes (pMHCII). These pMHCII are then presented to CD4+ T cells on the surface of APCs to trigger an antigen-specific immune response against the pathogens. HLA-DM (DM), a non-classical MHCII molecule, plays an essential role in generating kinetically stable pMHCII complexes which are presented to CD4+ T cells. When a few peptides among the pool of the peptide repertoire can generate the efficient CD4+ T cell response, such peptides are known as immunodominant. The selection of immunodominant epitopes is essential to generate effective vaccines against pathogens. The mechanism behind immunodominant epitope selection is not clearly understood. My work is focused on investigating various factors that help in the selection of immunodominant epitopes. For this purpose, peptides derived from H1N1 influenza hemagglutinin protein with known CD4+ T cell responses have been used. We investigated the role of DM-associated binding affinity in the selection of immunodominant epitopes. Our analysis showed that the presence of DM significantly reduces the binding affinity of the peptides with low CD4+ T cell response and inclusion of DM-associated IC50 in training MHCII algorithms may improve the binding prediction. Previous studies have shown that there is an alternate antigen presentation depending on antigen protein properties. Here, we showed that the immunodominant epitope presentation is dependent on the pH and length of the peptides. To study the MHCII in its native form, we assembled full-length MHCII in a known synthetic membrane model known as nanodiscs. We noted that, based on the lipid composition, assembly of the MHCII differs. Preliminary binding studies with this tool showed that there might be a difference in the binding based on the type of the nanodisc. Collectively, our results showed that the immunodominant epitope selection is a complex process that is driven by various biochemical features.
  • Influence of permafrost extent on photochemical reactivity, functional group composition, and geochemical cycling of a subarctic discontinuous permafrost Alaskan watershed

    Gagné, Kristin R.; Guerard, Jennifer J.; Simpson, William; Trainor, Thomas P.; Jones, Jeremy (2020-05)
    Sub-Arctic Alaskan boreal forests are currently extremely susceptible to permafrost thaw caused by increases in atmospheric temperatures in the region. Upon thaw, permafrost soil organic matter can leach out organic matter, nitrogen, and metals. It is important to observe the effects the leaching of permafrost may have on photoreactivity, functional group composition, and metal introduction. Photoproduced reactive oxygen species may affect metal fate and transport through mechanisms such as the photo-Fenton reaction. Functional group analysis allows for differences in natural organic matter source and ability to complex metals throughout a watershed. Additionally, permafrost soils may have the ability to leach in metals through lateral flow of surface waters as observed in other studies. These metals could then complex to organic matter and alter the geochemical cycling within the watershed. Organic matter is a nutrient source, and metals (e.g., As) may increase the toxicity of surface waters through the thaw of permafrost. The influx of sequestered organic matter and metals to surface waters has the potential to drastically alter ecosystem processes. This study observes how permafrost leaching affects water composition, including its overall photoreactivity and functional group composition. The data obtained was then used to observe and deduce conclusions on how permafrost thaw influences surface water photoreactivity and functional group composition. Finally, trace metal analysis was conducted on a whole watershed scale over three years to observe how permafrost influences the geochemical composition of three main thermokarst surface waters with varying degrees of permafrost degradation. Overall, permafrost was determined to be heterogeneous and highly photoreactive both inter- and intra- watershed. Additionally, the functional group composition of surface waters influenced by permafrost thaw was different between summer and winter, indicating that winter is an important period to sample. Due to this change in functional group composition, the photoreactivity of winter samples was higher than summer with regard to the production of reactive oxygen species. Metal concentrations also increased during the winter for lakes identified to be undergoing active permafrost thaw. Finally, this case study found that metal concentration data combined with optical indices provided important information for resolving the possible extent of permafrost beneath thermokarst lakes.
  • Characterizing wintertime aerosol composition and sulfate formation in Fairbanks, Alaska

    Davey, Ragen; Mao, Jingqiu; Simpson, William R.; Guerard, Jennifer J. (2020-05)
    The citizens of Fairbanks, Alaska are exposed to high levels of air pollutants throughout the winter months, causing the city to violate the Fine Particulate Matter (PM₂.₅) National Ambient Air Quality Standards set in place by the United States Environmental Protection Agency. Previous studies have shown the significant amount of sulfate aerosols particles observed in Fairbanks winters, but the formation mechanism of aerosols containing sulfate in the atmosphere is still unknown. While sulfate aerosol particle formation is commonly driven by oxidants including ·OH, H₂O₂ and O₃, these photochemical species are limited in Fairbanks winter months. This indicates sulfate aerosol particle formation may occur through a nontraditional pathway, and this project investigates one proposed mechanism in which transition metals may catalyze sulfate aerosol particle formation. We collected twelve full diurnal cycles over the winter months of 2019, using a particle-to-liquid sampler (PILS) at hourly time resolution. This PILS instrument creates an aqueous extract containing only the water-soluble components of the aerosol particles. These aqueous extracts were analyzed offline for inorganic and metal concentrations by ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS). This hourly dataset provides new insights in emissions, chemical processing and their coupling with boundary layer dynamics. We find a strong correlation between hourly sulfate and PM2.5 mass concentrations, but we do not find the strong evidence of transition metal ion (TMI) catalysis on sulfate formation. We also collected twelve sets of aerosol filters using Micro-Orifice Uniform Deposit Impactor (MOUDI) throughout the winter of 2019. These size-resolved filter samples suggest the presence of hydroxymethane sulfonate (HMS) in submicron particles when temperatures are below -30 °C (-22 °F), suggesting a new reservoir for sulfur compounds in Fairbanks winter and warranting further investigation.
  • Phylogenetic relationships within the Western United States species of Lepidium l.

    Lichvar, Robert W.; Laursen, Gary; Duffy, Lawrence; Dorn, Robert; Wolf, Paul (2019-12)
    The genus Lepidium L. is one of two global genera in the Brassicaceae. The genus has been arranged by species (geographic regions) worldwide, but no formal levels below the genus are recognized. Recent efforts to evaluate phylogenetic relationships have been performed at the global scale for about 20 percent of the species in the genus. The genus is recognized as having subtle and variable morphological characteristics to define species limits. Several nuclear and chloroplast DNA methods have been used to construct phylogenetic relationships within the genus. Incongruences between various phylogenetic trees indicate likely hybridization and/or hybrid origin of multiple species and a genus blurred with a reticulate evolutionary past. Internal Transcribed Spacer (ITS) ribosomal DNA (rDNA) sequences were developed here and combined with other ITS sequences on Genbank for other North American species of Lepidium. Two phylogenetic trees were developed, one comparing North American and another dominated by Intermountain West species. Results of a limited Intermountain Lepidium phylogenetic tree were compared to a cladistic tree developed from 123 morphological traits for select species of Lepidium from the western United States. A comprehensive ITS tree was developed to evaluate species relationships in the genus throughout this region. Ploidy levels of 22 taxa of Intermountain species of Lepidium were evaluated to assess whether ploidy levels were associated with any geographic or morphologic patterns within the group. The results show closely related species and varieties with several ploidy levels, but are lacking any relationships to morphological features. Neither ITS nor ploidy levels provided a clear understanding into the current taxonomic treatment of the many faint morphologically different taxa in the group. But Intermountain Lepidium, as a geographic group and clade, is distinct from other west coast members in the genus. The species most associated with all the radiant speciation, and the least understood, is L. montana.
  • Modeling volcanic ash and sulfur dioxide with the Weather Research Forecasting with Chemistry (WRF-Chem) model

    Egan, Sean D.; Cahill, Catherine; Stuefer, Martin; Webley, Peter; Lopez, Taryn; Simpson, William (2019-12)
    The Weather Research Forecasting with Chemistry (WRF-Chem) model is capable of modeling volcanic emissions of ash, sulfur dioxide and water vapor. Here, it is applied to eruptions from three volcanoes: the 2008 eruption of Kasatochi Volcano in Alaska, the 2010 eruption of Eyjafjallajökull in Iceland and the 2019 eruption of Raikoke in the Kurile Islands. WRF-Chem's ability to model volcanic emissions dispersion is validated through comparison of model output to remote sensing, in situ and field measurements. A sensitivity of the model to modeled plume height is discussed. This work also modifies the base WRF-Chem code in three ways and studies the effects of these modifications. First, volcanic ash aggregation parameterizations are added covering three modes of particle collisions through Brownian motion, differential settling and shear. Second, water vapor emissions from volcanic eruptions are added and coupled to the new aggregation scheme. The effects of these changes are assessed and found to produce volcanic ash concentrations in agreement with in situ measurements of plume concentrations and field measurements of tephra fallout. Third, the model is adapted to include multiple model initializations such that each is perturbed by selecting between two volcanic ash particle sizes and five initial plume heights. This modified WRF-Chem is nested in an application program interface that enables a new, automated, near real-time capability. This capability is assessed and the feasibility of its use as an augmenting tool to current operational VATD models is commented upon.
  • Mechanisms regulating the circannual rhythm of hibernation

    Frare, Carla; Drew, Kelly L.; Bult-Ito, Abel; Green, Thomas K.; Kuhn, Thomas B. (2019-08)
    Hibernation is a unique adaptation to conserve energy entering a hypometabolic (low metabolic rate) and hypothermic (low body temperature) state called torpor. Torpor is characterized by a drop in metabolism to 1-2% of basal metabolic rate and a decrease in body temperature to one to two degrees above ambient temperature. Metabolic rate is restored to basal metabolic rate and body temperature increases from 2-3⁰C to 36⁰C during the regularly timed arousal. The adenosine A1 receptor agonists promote the onset of hibernation and torpor in different species, through a yet undefined neuronal circuit. In the Arctic ground squirrel, CHA, an adenosine A1 receptor agonist, induces hibernation during the winter- hibernation season but not in summer even when the environmental conditions are kept constant (ambient temperature of 2⁰C and a light cycle of 4L:20D). Thus, the phenomenon of CHA-induced hibernation is entrained to an endogenous circannual rhythm. In this work, I aim to identify the changes in neuronal activation that reflect the circannual rhythm regulating the seasonal difference in response to CHA. Arctic ground squirrels, housed at constant ambient temperature (2°C) and light cycle (4L:20D), were implanted with body temperature transmitters. I collected tissue during Summer, Fall, Winter and Torpor conditions for seasonal analysis. For treatment analysis, I collected tissue form animals treated with CHA or vehicle in Summer and Winter. Primarily, I used immunohistochemistry to identify cell groups affected by season and treatment. I used cFos to identify neuronal activity and other immunohistochemical markers to identify neuronal phenotypes, based on specific cytoplasmic proteins. An overall seasonal decrease in thermogenesis, measured as reduced neuronal activity in the thermoregulatory pathways, and increase in vasoconstriction reflected the higher order processing necessary for CHA-induced hibernation. CHA inhibited the histaminergic neurons in the hypothalamus suppressing wakefulness and dis-inhibited the nucleus tractus solitarius, further suppressing thermogenesis. Preliminary data also suggested a seasonal change in the adenosine metabolic pathway, which may have increased adenosine receptor sensitivity during the hibernation season. Our results suggest that histaminergic neurons in the hypothalamus and the nucleus tractus solitarius are likely targets to manipulate metabolic demand in the clinical setting inducing therapeutic hypothermia or increasing metabolic rate.
  • Role of antioxidant supplementation and exercise regimen in handling oxidative stress from natural PM2.5 exposure due to boreal forest fire

    Witkop, Jacob J.; Dunlap, Kriya; Duffy, Lawrence; Reynolds, Arleigh (2019-05)
    Particulate matter 2.5 (PM2.5) exposure induces oxidative stress that causes many negative health outcomes such as cancer, cardiovascular disease and neurodegenerative disease. Research shows that dietary antioxidants and an up-regulated endogenous antioxidant response from exercise play key roles in the antioxidant defense against oxidative stress. This study is the first to use an animal model to investigate the cumulative effects of using lifestyle interventions of antioxidant supplementation (Arthrospira platensis) and exercise regimen on the antioxidant response before, during, and after ambient PM2.5 exposure. In a two-factorial, longitudinal design, sled dogs (n=48) were divided into four groups (exercise and supplemented, exercise, supplemented, and control) to (1) test the effects of exercise and antioxidant regimen on antioxidant response after one month of implemented exercise and supplementation protocol and (2) measure the antioxidant response of all groups during and after a natural forest fire event in 2015. Commercial assays for Total antioxidant Power (TAP) and the enzymatic antioxidant Superoxide Dismutase (SOD) were used as markers for the total antioxidant response and the endogenous response at all time points. During the forest fire, SOD was increased 5-10-fold over pre/post-exposure levels in all groups suggesting potential implication for using SOD as a marker for the acute response to environmental stress. TAP was increased in the exercise groups after one month of exercise protocol implementation, demonstrating the cytoprotective increase of antioxidants after repeated exercise.
  • Determining the immune status of Steller sea lions (Eumetopias jubatus): an environmental agents of disease perspective

    Kennedy, Stephanie Nichole; O'Hara, Todd; Ferrante, Andrea; Kuhn, Thomas; Trainor, Thomas; Rea, Lorrie (2019-05)
    The integrity of the immune system is paramount for preserving overall health for many organisms. Investigating environmental and physiological factors that may be associated with alterations of the immune status in non-traditional sentinel species, like the Steller sea lion (SSL), is a prominent undertaking in eco-immunology research. Changes to immune homeostasis likely impacts the health and survival of SSLs. Recent studies have reported that mercury concentrations in hair in 24 to 36% of newborn SSLs of the Western Aleutian Islands (WAI) exceed thresholds (>30 ppm) for potential adverse effects. Many of these individuals were from WAI rookeries that have historically experienced significant population declines with some slow to recover. Retrospective, and ongoing, analyses of mercury in lanugo coats (natal hair) from young pups of the WAI demonstrate in utero exposure to relatively high levels of mercury during late gestation. Therefore, this dissertation focuses on the notion that dietary acquired mercury could potentially alter immune response in SSLs, especially young pups, and may contribute to the lack of recovery from population declines. In order to gain an understanding of the potential for mercury to adversely affect the immune response of SSLs, selected aspects of immunity were measured (blood cell counts, haptoglobin, immunoglobulins, and cytokines) and investigated within the context of body condition, age, mercury exposure and regional population dynamics. In Chapter Two, the acute phase response protein, haptoglobin, was found to vary significantly with age and region. Individual SSL pups with greater concentrations of mercury had lower predicted concentrations of haptoglobin. In Chapter Three, a colorimetric protein A enzyme-linked immunosorbent assay was modified for enhancing accurate measurement of immunoglobulin concentrations in SSL serum. This improved methodology was then used in Chapter Four for comparing immunoglobulins in young developing SSL pups and dams as a measure of maternal investment of immunity among different rookeries. Lastly, Luminex multiplex technologies were employed for quantifying cell-signaling proteins (cytokines) in SSL serum to compare associations among rookery pups in Chapter Five. Although mercury concentrations in some individuals exceed adverse effects thresholds that are defined for other mammals, no statistically significant associations were found between immunoglobulins and cytokines relative to mercury concentrations in young developing pups. These thesis chapters provide a powerful baseline and improved methods for ongoing and future assessments of haptoglobin, immunoglobulins, and cytokines (combined with traditional hematologic measures) observed in young developing SSL pups in regions experiencing population decline when compared with rookeries with stable or increasing pup production. Some of these findings, especially for haptoglobin, are indicative of alterations in immune status in young SSL pups born to dams from different natal rookeries with higher mercury exposure. Understanding the cause of the differences in the immune status of young SSLs will require additional assessments of the maternal-fetal interface of immunity and other factors like nutrition, metabolic status, and infectious disease that may shape neonatal immunity leading to the regional differences observed.
  • Effects of methylmercury and theaflavin digallate on adipokines in mature 3t3-l1 adipocytes

    Chauhan, Shubhangi; Duffy, Lawrence; Drew, Kelly; Dunlap, Kriya (2019-05)
    Diabetes is a contributor to morbidity across the globe and is often associated with obesity, metabolic syndrome and other inflammatory diseases associated with aging. In addition to genetic and lifestyle factors, environmental factors such as metals and persistent organic pollutants may increase the severity or lower the threshold of these conditions. In cell culture, methylmercury is toxic to adipocytes and may impact the adipokine secretions. In this study, I determined the effects of different concentrations of theaflavin digallate on methylmercury exposed 3T3-L1 adipocytes in cell culture. Secretions of resistin, adiponectin and lipid peroxidation product, 4-HNE were monitored using ELISA assays from Day 18 to 28. Cell morphology was assessed over the period of ten days and on day 28 was observed using Lipid (Oil Red O) staining. Results showed that exposure to methylmercury increased the levels of resistin and adiponectin as well as 4-HNE when compared to the control cells. Methylmercury treated cells resulted in smaller and highly clumped lipid droplets. These results suggest that methylmercury induces reactive oxygen species leading to development of an inflammatory response. Theaflavin digallate reduced the impact of methylmercury by restoring the morphology and secretion patterns of adiponectin, resistin and 4-HNE. With this enhanced signaling model other anti-inflammatory agents could be tested at this biochemical level eventually leading to studies in animal models.
  • Metal(loid) liberation from Alaskan coal combustion products as a function of time in various aqueous media

    Milke, Kyle P.; Guerard, Jennifer J.; Hayes, Sarah M.; Trainor, Thomas P. (2018-12)
    Little is known about the fate and potential toxicity of metal(loid)s that could be leached from coal combustion products by a (sub- )Arctic environment. Several potentially toxic elements are enriched in coal combustion products relative to the average crustal abundance including As, Cu, Se, and Sb. The overarching goal of this project is to examine the release of these and other metal(loid)s from early stage coal ash and fly ash from the University of Alaska Fairbanks (UAF) power plant and identify transformations in the presence of aqueous environmental media. Bioaccessibility experiments performed indicate that early stage coal ash and fly ash contain bioaccessible Cr, As, Se, Sb, and Pb. Bioaccessible concentrations of these commonly known toxic metal(loid)s were found to exceed EPA drinking water and freshwater regulations. Early stage coal ash and fly ash was reacted with 18 MΩ H₂O (control) or simulated rainwater to quantify metal(loid) liberation as a function of time. Leachate pH increased to ca. 12.5 within the first hour. Some metal(loid)s quickly reached the maximum measured concentration and consistently decreased in concentration with time such as Ba, Pb, and Zn, while other metal(loid)s increased in concentration with increased reaction time (e.g., Al, V, and Cr). Leaching behavior of between early stage coal ash and fly ash may be controlled by total initial concentrations present in the two ashes, differences in particle size, dissolution and precipitation reactions, and heterogeneity of metal(loid) distribution within the particles. Early stage coal ash and fly ash were also reacted with reconstituted dissolved organic matter solutions to simulate possible environmental interactions. It was found that for some elements (e.g., Ca), dissolved organic matter did not affect the mobility. Other metal(loid) mobilities were affected by the presence of dissolved organic matter, such as that of Sb, As, Zn, Se, Mo, and V. Some metal(loid) concentrations decreased while others increased with increasing dissolved organic carbon concentrations. Through these experiments, we have obtained a quantitative understanding of the kinetic controls of metal(loid) release from coal ash leaching with various aqueous media. Results from these experiments can help to improve storage and remediation processes for coal combustion products in an effort to protect human and the ecosystem health.
  • Role of dietary fat and supplementation in modulating neurodegenerative pathology in two animal model systems

    Maulik, Malabika; Bult-Ito, Abel; Taylor, Barbara E.; Duffy, Lawrence; Kuhn, Thomas; Dunlap, Kriya (2018-12)
    Neurodegenerative disorders are progressive conditions that worsen over time and results in death of neurons. Parkinson's disease (PD) is a prevalent example of one such age-related disease, which is characterized by movement disorder (ataxia) and/or cognitive disability (dementia). Pathologically, PD is characterized by a toxic accumulation of α-synuclein protein in the midbrain leading to degeneration of the dopaminergic neurons. The etiology of PD is intricate, and the cause is attributed to genetic mutations and environmental factors like insecticides or heavy metals. Moreover, treatment options are limited and often aimed at treating the symptoms rather than the actual disease progression. Using the nematode model of Caenorhabditis elegans, I examined the effect of Alaskan bog blueberry (Vaccinium uliginosum) on α-synuclein overexpression and how such indigenous natural treatment can modulate key molecular targets like sirtuins, which are proteins involved in regulating cellular processes including aging, death and their resistance to stress. The impact of extrinsic factors like dietary fat on PD pathology has been sparsely explored and the molecular basis of such changes is not known. Through my thesis research, I also further investigated the influence of fat metabolism on key hallmarks of PD: α-synuclein overexpression and dopaminergic degeneration in the nematode model. Finally, I studied the interaction of dietary fat (normal, low and high fat) and Alaskan blueberry supplementation on metal induced neurotoxicity model of Mus musculus. Our results highlight the beneficial properties of Alaskan blueberries in combating proteotoxic stress and inflammation in both animal models. They also reiterate the benefit of low fat diet, on its own or in combination with supplementation in improving several PD-like molecular features and how consuming high fat can mask such health promoting outcomes. The current thesis work therefore, provides a foundation for further exploration of neurobiological changes associated with consumption of natural products and different diets and how such alterations can be extrapolated to humans.
  • The temporal and spatial distribution of dissolved and particulate iron over the Gulf of Alaska shelf

    Roberts, Megan Victoria; Aguilar-Islas, Ana M.; Trainor, Thomas P.; Simpson, William (2018-08)
    The Gulf of Alaska (GOA) is a region with contrasting ecosystems where the availability of the essential micronutrient iron (Fe) contributes to the observed productivity. However, knowledge on the temporal and spatial variability of iron species over the GOA shelf is limited. The offshore GOA displays lower annual production and residual nitrate in surface waters throughout the year due to low Fe supply, while high spring production is observed over the shelf due to ample nitrate and Fe supply, but these waters become nitrate limited by mid-summer. Processes promoting the exchange of the Fe rich shelf waters with the nitrate rich offshore GOA waters create favorable conditions for phytoplankton to bloom. Mechanisms for Fe introduction and transport are seasonal freshwater input, alongshore advection from the Alaska Coastal Current eddies, deep wintertime mixing, downwelling, downwelling relaxation, and/or upwelling conditions. Additional Fe sources from subsurface waters and sediment re-suspension can impact Fe distributions. Highly seasonal glacial and river input bring in an abundance of both particulate and dissolved Fe species, which differ in their biological availability. For example, dissolved Fe (DFe) is much more readily available than particulate Fe (PFe). The PFe pool can be separated into a labile fraction, which is potentially transferable to the dissolved phase on time scales relevant to phytoplankton blooms, and a refractory fraction, which is considered biologically unavailable. Seawater samples to determine Fe speciation were collected in spring and early fall of 2013 during three GOA scientific cruises. Trace metal clean procedures were followed during sample collection, processing and analysis. Seawater samples were collected by two methods: 1) Vertical samples were obtained using custom-made samplers (UAF vanes) and filtered offline for PFe analysis; 2) surface samples were obtained by using a towed pump system ("the Fe fish") and filtered in-line for DFe analysis. The PFe fractions of suspended particles were further processed using chemical separation: a) 25 % acetic acid leach with a reducing agent to determine leachable particulate Fe; b) complete digestion of the filter using strong acids to determine refractory particulate Fe. Quantitative determination was by inductively coupled plasma mass spectrometry. Results indicate the broader Western GOA shelf displayed higher average concentrations of total particulate Fe (~121 nM on average) compared to the narrower Southeastern GOA shelf (~18 nM on average). Areas of high glacial input, such as in the vicinity of the Copper River discharge (western side of Kayak Island) and within Prince William Sound near Columbia Glacier, exhibited highly elevated concentrations of total particulate Fe (~430 nM to ~1100 nM). When comparing geographic location, the suspended leachable particulate Fe was higher (~ 22%) over the Southeastern shelf, while the Northern and Western shelf had lower percentage of leachable Fe (11 - 12 %). Over the Southeastern shelf, DFe concentrations were higher in late spring ranging (0.22 - 3.13 nM), while in early fall concentrations were lower (0.07 - 0. 84 nM). Surface water results indicate that there is a significant input of PFe and DFe that occurs in the early fall that extends over much of the Northern shelf and at the inner Western shelf. Variability in downwelling, downwelling relaxation, and upwelling conditions were observed to impact Fe distributions over the Southeastern shelf. These results highlight the impact that the intense environmental variability characteristic of the GOA has on the distribution of Fe species seasonally and geographically.
  • New instrumentation for the detection of sulfur dioxide in the remote atmosphere

    Nicks, Dennis Keith, Jr.; Benner, Richard (1999)
    Sulfur gases are an important chemical component of the atmosphere. Gaseous sulfur compounds effect the acidity of rainwater and are important precursors to aerosol particles which affect public health, climate and visibility of scenic vistas such as the Grand Canyon. Sulfate aerosols are also known to participate in ozone catalysis in the stratosphere. A vast majority of the gaseous sulfur cycling through the atmosphere will exist as sulfur dioxide (SO2) at some time during its atmospheric lifetime. Since SO 2 is a primary component of the atmospheric sulfur cycle, quality measurements of this gas are important to understanding the cycling of sulfur through the atmosphere. The mixing ratio of SO2 in the atmosphere can be as low as a few 10's of parts-per-trillion by volume (pptv) in unpolluted areas and as high as 100's of parts-per-billion by volume (ppbv) near industrial centers. Obtaining SO2 measurements with mixing ratios that can differ by 105 in magnitude is a difficult task, especially for mixing ratios less than a few hundred pptv. The Diffusion Denuder/Sulfur Chemiluminescence Detector (DD/SCD) was developed further and tested in a rigorously blind comparison under controlled laboratory conditions. The DD/SCD exhibited excellent sensitivity and little-to-no interference from other trace gases. The DD/SCD performance was comparable to that of other state-of-the-art instruments developed for measuring SO 2 in the remote atmosphere. The Continuous SO2 Detector was developed to overcome the limitation of long sampling times (4 to 90 minutes) inherent in the DD/SCD and other state-of-the-art techniques. The Continuous SO2 Detector (CSD) was developed based on the design of the DD/SCD, but has been optimized for sensitive, high-time resolved measurements of SO2 in air. Sensitive, high-time resolved measurements would be beneficial for studying atmospheric SO2 over large geographical areas from a moving sampling platform such as an aircraft. The current prototype of the CSD is capable of measuring SO2 at mixing ratios of less than 100 pptv on the order of seconds. The DD/SCD, CSD and an automated, computer controlled dynamic dilution system described in this thesis represent a suite of instruments for the measurement of SO2 in the remote atmosphere.
  • Molecular systematics and biogeography of long-tailed shrews (Insectivora: Sorex) and northern flying squirrels (Rodentia: Glaucomys)

    Demboski, John Richard; Cook, Joseph A. (1999)
    Insight into phylogenetic and biogeographic relationships among several mammalian taxa in western North America was provided with DNA sequences of two mitochondrial genes (cytochrome b and ND4). Members of two species complexes of long-tailed shrews (genus Sorex ) and northern flying squirrels (genus Glaucomys) were examined, and a common theme of responses to past climate change and glacial cycles was evident. Diversification events indicated by the DNA sequences provide new perspectives regarding the deep and shallow history of these taxa. Analysis of seven species of the Sorex cinereus complex (and related species) revealed two major clades within the complex, Northern and Southern. These generally corroborate proposed morphological relationships and correspond to broadly defined habitat affiliations (xeric and mesic), respectively. Within the Northern clade, amphiberingian species represented a monophyletic group suggesting Beringia was a center of endemism. Next, five species of the S. vagrans complex and related species were assessed. Significant molecular variation was revealed that does not correspond to morphological differences within the complex. Two major clades within S. monticolus were observed, a widespread Continental clade (Arizona to Alaska, including S. neomexicanus) and a restricted Coastal clade (Oregon to southeast Alaska, including S. bairdi and S. pacificus). A regional examination of genetic variation in the northern flying squirrel in southeast Alaska was also performed. Results suggested that southern islands in the Alexander Archipelago were the result of recent colonization (founder event). Finally, a comparative phylogeographic analysis of a reduced data set (S. monticolus), a molecular data set for the American Pine Marten, Martes americana, and other published molecular studies were used to reexamine the role of glacial refugia in the biogeography of the north Pacific coast. Previous ideas regarding purported refugia may be overstated and may be the result of limited geographic sampling. This thesis provides new perspectives on processes (e.g., post-glacial colonization) driving mammalian phylogenetic and biogeographic structuring in western North America.
  • Investigations into model systems of neurodegeneration: Organotypic brain slice culture and in vivo microdialysis

    Clapp, Kimberly Lara; Duffy, Lawrence K. (2000)
    The mechanisms behind neurodegeneration in disease and injury have yet to be fully defined. Many in vitro and in vivo model systems, have been developed to investigate the mechanisms of neurotoxicity and its relation to human disease and injury. There are a few resounding connections between most types of neurological disorder; namely oxidative stress and inflammation. The glutamate receptor agonist, N-methyl-D-aspartate, can be used to imitate excitotoxicity during stroke as it overstimulates the glutamate receptor, leading to rises in intracellular calcium levels, which in turn lead to oxidative stress within the cell. Amyloid-beta protein (Abeta) a useful in many of its isoforms in creating in vitro model systems of Alzheimer's disease (AD). Abeta can directly cause the production of potentially harmful free radicals. This study investigates the formation of model systems of neurodegeneration: in vivo microdialysis and organotypic brain slices culture in order to assess the role of oxidative stress and inflammation morphologically and biochemically. The effect of melatonin, an endogenous antioxident, on oxidative stress associated with NMDA and Abeta neurotoxicity was determined through morphological analysis and biochemical markers of oxidative stress. This study reports that both NMDA and Abeta(25--35) cause oxidative stress in an organotypic brain slice culture model system of stroke and Alzheimer's disease as established by: (1) morphological analysis of tissue and ultrastructure, (2) redox-active assay, (3) heme-oxygenase assay, (4) 8-hydroxyguanosine assay and (5) interleukin IL-1beta and IL-6 assay (Abeta only) These investigations also demonstrate that melatonin can attenuate the oxidative stress associated with NMDA and Abeta exposure. These findings expand upon previous evidence from cell culture analysis of oxidative stress induced by NMDA and Abeta. Therefore, this evidence supports the theory that oxidative stress is involved in neurodegeneration in both excitotoxicity in stroke and in Abeta-mediated damage in Alzheimer's disease, and that endogenous antioxidant treatment may be a useful therapeutic approach in such injury and disease.
  • Oceanic emissions of sulfur: Application of new techniques

    Jodwalis, Clara Mary; Benner, Richard L. (1998)
    Sulfur gases and aerosols are important in the atmosphere because they play major roles in acid rain, arctic haze, air pollution, and climate. Globally, man-made and natural sulfur emissions are comparable in magnitude. The major natural source is dimethyl sulfide (DMS) from the oceans, where it originates from the degradation of dimethysulfonioproprionate (DMSP), a compound produced by marine phytoplankton. Global budgets of natural sulfur emissions are uncertain because of (1) the uncertainty in the traditional method used to estimate DMS sea-to-air flux, and (2) the spatial and temporal variability of DMS sea-to-air flux. We have worked to lessen the uncertainty on both fronts. The commonly used method for estimating DMS sea-to-air flux is certain to a factor of two, at best. We used a novel instrumental technique to measure, for the first time, sulfur gas concentration fluctuations in the marine boundary layer. The measured concentration fluctuations were then used with two established micrometeorological techniques to estimate sea-to-air flux of sulfur. Both methods appear to be more accurate than the commonly used one. The analytical instrument we used in our studies shows potential as a direct flux measurement device. High primary productivity in high-latitude oceans suggests a potentially large DMS source from northern oceans. To begin to investigate this hypothesis, we have measured DMS in the air over northern oceans around Alaska. For integrating and extrapolating field measurements over larger areas and longer time periods, we have developed a model of DMS ocean mixing, biological production, and sea-to-air flux of DMS. The model's main utility is in gaining intuition on which parameters are most important to DMS sea-to-air flux. This information, along with a direct flux measurement capability, are crucial steps toward the long-term goal of remotely sensing DMS flux. A remote sensing approach will mitigate the problems of spatial and temporal variability. The new developments in methodology, field sampling, and modeling put forth in this thesis are tools we have used to better understand and quantify sulfur gas emissions from northern oceans, which appear to be a significant source of sulfur to the global atmosphere.

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