Matching Items (170)
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Humans have greatly altered the night-time photic environment via the production of artificial light at night (ALAN; e.g. street lights, car traffic, billboards, lit buildings). ALAN is problematic because it may significantly alter the seasonal/daily physiological rhythms or behaviors of animals. There has been considerable interest in the impacts of

Humans have greatly altered the night-time photic environment via the production of artificial light at night (ALAN; e.g. street lights, car traffic, billboards, lit buildings). ALAN is problematic because it may significantly alter the seasonal/daily physiological rhythms or behaviors of animals. There has been considerable interest in the impacts of ALAN on health in humans and lab animals, but most such work has centered on adults and we know comparatively little about effects on young animals. We exposed 3-week-old king quail (Excalfactoria chinensis) to a constant overnight blue-light regime for 6 weeks and assessed weekly bactericidal activity of plasma against Escherichia coli - a commonly employed metric of innate immunity in animals. We found that chronic ALAN exposure significantly increased immune function, and that this elevation in immune performance manifested at different developmental time points in males and females. These results counter the pervasive notion that overnight light exposure is universally physiologically harmful to diurnal organisms and indicate that ALAN can provide sex-specific, short-term immunological boosts to developing animals.
ContributorsSaini, Chandan (Author) / McGraw, Kevin (Thesis director) / Hutton, Pierce (Committee member) / Sweazea, Karen (Committee member) / Department of Psychology (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
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The City of Phoenix Street Transportation Department partnered with the Rob and Melani Walton Sustainability Solutions Service at Arizona State University (ASU) and researchers from various ASU schools to evaluate the effectiveness, performance, and community perception of the new pavement coating. The data collection and analysis occurred across multiple neighborhoods

The City of Phoenix Street Transportation Department partnered with the Rob and Melani Walton Sustainability Solutions Service at Arizona State University (ASU) and researchers from various ASU schools to evaluate the effectiveness, performance, and community perception of the new pavement coating. The data collection and analysis occurred across multiple neighborhoods and at varying times across days and/or months over the course of one year (July 15, 2020–July 14, 2021), allowing the team to study the impacts of the surface treatment under various weather conditions.

Created2021-09
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The oceanic biological carbon pump is a key component of the global carbon cycle in which dissolved carbon dioxide is taken up by phytoplankton during photosynthesis, a fraction of which then sinks to depth and contributes to oceanic carbon storage. The small-celled phytoplankton (<5 µm) that dominate the phytoplankton community

The oceanic biological carbon pump is a key component of the global carbon cycle in which dissolved carbon dioxide is taken up by phytoplankton during photosynthesis, a fraction of which then sinks to depth and contributes to oceanic carbon storage. The small-celled phytoplankton (<5 µm) that dominate the phytoplankton community in oligotrophic oceans have traditionally been viewed as contributing little to export production due to their small size. However, recent studies have shown that the picocyanobacterium Synechococcus produces transparent exopolymer particles (TEP), the sticky matrix of marine aggregates, and forms abundant microaggregates (5-60 µm), which is enhanced under nutrient limited growth conditions. Whether other small phytoplankton species exude TEP and form microaggregates, and if these are enhanced under growth-limiting conditions remains to be investigated. This study aims to analyze how nutrient limitation affects TEP production and microaggregate formation of species that are found to be associated with sinking particles in the Sargasso Sea. The pico-cyanobacterium Prochlorococcus marinus (0.8 µm), the nano-diatom Minutocellus polymorphus (2 µm), and the pico-prasinophyte Ostreococcus lucimarinus (0.6 µm) were grown in axenic batch culture experiments under nutrient replete and limited conditions. It was hypothesized that phytoplankton subject to nutrient limitation will aggregate more than those under replete conditions due to an increased exudation of TEP and that Minutocellus would produce the most TEP and microaggregates while Prochlorococcus would produce the least TEP and microaggregates of the three phytoplankton groups. As hypothesized, nutrient limitation increased TEP concentration in all three species, however they were only significant in nitrogen-limited treatments of Prochlorococcus as well as nitrogen- and phosphorus-limited treatments of Minutocellus. Formation of microaggregates was significantly enhanced in Minutocellus and Ostreococcus cultures in distinct microaggregate size ranges. Minutocellus produced the most TEP per cell and aggregated at higher volume concentrations compared to Prochlorococcus and Ostreococcus. Surprisingly, Ostreococcus produced more TEP than Prochlorococcus and Minutocellus per unit cell volume. These findings show for the first time how nutrient limited conditions enhance TEP production and microaggregation of Prochlorococcus, Minutocellus, and Ostreococcus, providing a mechanism for their incorporation into larger, sinking particles and contribution to export production in oligotrophic oceans.
ContributorsShurtleff, Catrina (Author) / Neuer, Susanne (Thesis advisor) / Lomas, Michael W. (Committee member) / Garcia-Pichel, Ferran (Committee member) / Arizona State University (Publisher)
Created2022
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Under current climate conditions northern peatlands mostly act as C sinks; however, changes in climate and environmental conditions, can change the soil carbon decomposition cascade, thus altering the sink status. Here I studied one of the most abundant northern peatland types, poor fen, situated along a climate gradient from tundra

Under current climate conditions northern peatlands mostly act as C sinks; however, changes in climate and environmental conditions, can change the soil carbon decomposition cascade, thus altering the sink status. Here I studied one of the most abundant northern peatland types, poor fen, situated along a climate gradient from tundra (Daring Lake, Canada) to boreal forest (Lutose, Canada) to temperate broadleaf and mixed forest (Bog Lake, MN and Chicago Bog, NY) biomes to assess patterns of microbial abundance across the climate gradient. Principal component regression analysis of the microbial community and environmental variables determined that mean annual temperature (MAT) (r2=0.85), mean annual precipitation (MAP) (r2=0.88), and soil temperature (r2=0.77), were the top significant drivers of microbial community composition (p < 0.001). Niche breadth analysis revealed the relative abundance of Intrasporangiaceae, Methanobacteriaceae and Candidatus Methanoflorentaceae fam. nov. to increase when MAT and MAP decrease. The same analysis showed Spirochaetaceae, Methanosaetaceae and Methanoregulaceae to increase in relative abundance when MAP, soil temperature and MAT increased, respectively. These findings indicated that climate variables were the strongest predictors of microbial community composition and that certain taxa, especially methanogenic families demonstrate distinct patterns across the climate gradient. To evaluate microbial production of methanogenic substrates, I carried out High Resolution-DNA-Stable Isotope Probing (HR-DNA-SIP) to evaluate the active portion of the community’s intermediary ecosystem metabolic processes. HR-DNA-SIP revealed several challenges in efficiency of labelling and statistical identification of responders, however families like Veillonellaceae, Magnetospirillaceae, Acidobacteriaceae 1, were found ubiquitously active in glucose amended incubations. Differences in metabolic byproducts from glucose amendments show distinct patterns in acetate and propionate accumulation across sites. Families like Spirochaetaceae and Sphingomonadaceae were only found to be active in select sites of propionate amended incubations. By-product analysis from propionate incubations indicate that the northernmost sites were acetate-accumulating communities. These results indicate that microbial communities found in poor fen northern peatlands are strongly influenced by climate variables predicted to change under current climate scenarios. I have identified patterns of relative abundance and activity of select microbial taxa, indicating the potential for climate variables to influence the metabolic pathway in which carbon moves through peatland systems.
ContributorsSarno, Analissa Flores (Author) / Cadillo-Quiroz, Hinsby (Thesis advisor) / Garcia-Pichel, Ferran (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Childers, Daniel (Committee member) / Arizona State University (Publisher)
Created2022
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The ability to find evidence of life on early Earth and other planets is constrained by the current understanding of biosignatures and our ability to differentiate fossils from abiotic mimics. When organisms transition from the living realm to the fossil record, their morphological and chemical characteristics are modified, usually resulting

The ability to find evidence of life on early Earth and other planets is constrained by the current understanding of biosignatures and our ability to differentiate fossils from abiotic mimics. When organisms transition from the living realm to the fossil record, their morphological and chemical characteristics are modified, usually resulting in the loss of information. These modifications can happen during early and late diagenesis and differ depending on local geochemical properties. These post-depositional modifications need to be understood to better interpret the fossil record. Siliceous hot spring deposits (sinters) are of particular interest for biosignature research as they are early Earth analog environments and targets for investigating the presence of fossil life on Mars. As silica-supersaturated fluids flow from the vent to the distal apron, they precipitate non-crystalline opal-A that fossilizes microbial communities at a range in scales (μm-cm). Therefore, many studies have documented the ties between the active microbial communities and the morphological and chemical biosignatures in hot springs. However, far less attention has been placed on understanding preservation in systems with complex mineralogy or how post-depositional alteration affects the retention of biosignatures. Without this context, it can be challenging to recognize biosignatures in ancient rocks. This dissertation research aims to refine our current understanding of biosignature preservation and retention in sinters. Biosignatures of interest include organic matter, microfossils, and biofabrics. The complex nature of hot springs requires a comprehensive understanding of biosignature preservation that is representative of variable chemistries and post-depositional alterations. For this reason, this dissertation research chapters are field site-based. Chapter 2 investigates biosignature preservation in an unusual spring with mixed opal-A-calcite mineralogy at Lýsuhóll, Iceland. Chapter 3 tracks how silica diagenesis modifies microfossil morphology and associated organic matter at Puchuldiza, Chile. Chapter 4 studies the effects of acid fumarolic overprinting on biosignatures in Gunnuhver, Iceland. To accomplish this, traditional geologic methods (mapping, petrography, X-ray diffraction, bulk elemental analyses) were combined with high-spatial-resolution elemental mapping to better understand diagenetic effects in these systems. Preservation models were developed to predict the types and styles of biosignatures that can be present depending on the depositional and geochemical context. Recommendations are also made for the types of deposits that are most likely to preserve biosignatures.
ContributorsJuarez Rivera, Marisol (Author) / Farmer, Jack D (Thesis advisor) / Hartnett, Hilairy E (Committee member) / Shock, Everett (Committee member) / Garcia-Pichel, Ferran (Committee member) / Trembath-Reichert, Elizabeth (Committee member) / Arizona State University (Publisher)
Created2021
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Predatory bacteria are a guild of heterotrophs that feed directly on other living bacteria. They belong to several bacterial lineages that evolved this mode of life independently and occur in many microbiomes and environments. Current knowledge of predatory bacteria is based on culture studies and simple detection in natural systems.

Predatory bacteria are a guild of heterotrophs that feed directly on other living bacteria. They belong to several bacterial lineages that evolved this mode of life independently and occur in many microbiomes and environments. Current knowledge of predatory bacteria is based on culture studies and simple detection in natural systems. The ecological consequences of their activity, unlike those of other populational loss factors like viral infection or grazing by protists, are yet to be assessed. During large-scale cultivation of biological soil crusts intended for arid soil rehabilitation, episodes of catastrophic failure were observed in cyanobacterial growth that could be ascribed to the action of an unknown predatory bacterium using bioassays. This predatory bacterium was also present in natural biocrust communities, where it formed clearings (plaques) up to 9 cm in diameter that were visible to the naked eye. Enrichment cultivation and purification by cell-sorting were used to obtain co-cultures of the predator with its cyanobacterial prey, as well as to identify and characterize it genomically, physiologically and ultrastructurally. A Bacteroidetes bacterium, unrelated to any known isolate at the family level, it is endobiotic, non-motile, obligately predatory, displays a complex life cycle and very unusual ultrastructure. Extracellular propagules are small (0.8-1.0 µm) Gram-negative cocci with internal two-membrane-bound compartmentalization. These gain entry to the prey likely using a suite of hydrolytic enzymes, localizing to the cyanobacterial cytoplasm, where growth begins into non-compartmentalized pseudofilaments that undergo secretion of vesicles and simultaneous multiple division to yield new propagules. I formally describe it as Candidatus Cyanoraptor togatus, hereafter Cyanoraptor. Its prey range is restricted to biocrust-forming, filamentous, non-heterocystous, gliding, bundle-making cyanobacteria. Molecular meta-analyses showed its worldwide distribution in biocrusts. Biogeochemical analyses of Cyanoraptor plaques revealed that it causes a complete loss of primary productivity, and significant decreases in other biocrusts properties such as water-retention and dust-trapping capacity. Extensive field surveys in the US Southwest revealed its ubiquity and its dispersal-limited, aggregated spatial distribution and incidence. Overall, its activity reduces biocrust productivity by 10% at the ecosystem scale. My research points to predatory bacteria as a significant, but overlooked, ecological force in shaping soil microbiomes.
ContributorsBethany Rakes, Julie Ann (Author) / Garcia-Pichel, Ferran (Thesis advisor) / Gile, Gillian (Committee member) / Cao, Huansheng (Committee member) / Jacobs, Bertram (Committee member) / Arizona State University (Publisher)
Created2022
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There is an estimated five trillion pieces of plastic in the global ocean, with 4.8 to 12.7 million metric tons entering the ocean annually. Much of the plastic in the ocean is in the form of microplastics, or plastic particles <5mm in size. Microplastics enter the marine environment as primary

There is an estimated five trillion pieces of plastic in the global ocean, with 4.8 to 12.7 million metric tons entering the ocean annually. Much of the plastic in the ocean is in the form of microplastics, or plastic particles <5mm in size. Microplastics enter the marine environment as primary or secondary microplastics; primary microplastics are pre-manufactured micro-sized particles, such as microbeads used in cosmetics, while secondary microplastics form from the degradation of larger plastic objects, such water bottles. Once in the ocean, plastics are readily colonized by a consortium of prokaryotic and eukaryotic organisms, which form dense biofilms on the plastic; this biofilm is termed the “plastisphere”. Despite growing concerns about the ecological impact of microplastics and their respective plastispheres on the marine environment, there is little consensus about the factors that shape the plastisphere on environmentally relevant secondary microplastics. The goal of my dissertation is to comprehensively analyze the role of plastic polymer type, incubation time, and geographic location on shaping plastisphere communities attached to secondary microplastics. I investigated the plastisphere of six chemically distinct plastic polymer types obtained from common household consumer products that were incubated in the coastal Caribbean (Bocas del Toro, Panama) and coastal Pacific (San Diego, CA) oceans. Genotyping using 16S and 18S rRNA gene amplification and next-generation Illumina sequencing was employed to identify bacterial and eukaryotic communities on the polymer surfaces. Statistical analyses show that there were no polymer-specific assemblages for prokaryotes or eukaryotes, but rather a microbial core community that was shared among plastic types. I also found that rare hydrocarbon degrading bacteria may be specific to certain chemical properties of the microplastics. Statistical comparisons of the communities across both sites showed that prokaryotic plastispheres were shaped primarily by incubation time and geographic location. Finally, I assessed the impact of biofilms on microplastic degradation and deposition and conclude that biofilms enhance microplastic sinking of negatively buoyant particles and reduce microplastic degradation. The results of my dissertation increases understanding of the factors that shape the plastisphere and how these communities ultimately determine the fate of microplastics in the marine environment.
ContributorsDudek, Kassandra Lynn (Author) / Neuer, Susanne (Thesis advisor) / Polidoro, Beth (Committee member) / Garcia-Pichel, Ferran (Committee member) / Cao, Huansheng (Committee member) / Arizona State University (Publisher)
Created2021
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With the development and successful landing of the NASA Perseverance rover, there has been growing interest in identifying how evidence of ancient life may be preserved and recognized in the geologic record. Environments that enable fossilization of biological remains are termed, “taphonomic windows”, wherein signatures of past life may be

With the development and successful landing of the NASA Perseverance rover, there has been growing interest in identifying how evidence of ancient life may be preserved and recognized in the geologic record. Environments that enable fossilization of biological remains are termed, “taphonomic windows”, wherein signatures of past life may be detected. In this dissertation, I have sought to identify taphonomic windows in planetary-analog environments with an eye towards the exploration of Mars. In the first chapter, I describe how evidence of past microbial life may be preserved within serpentinizing systems. Owing to energetic rock-water reactions, these systems are known to host lithotrophic and organotrophic microbial communities. By investigating drill cores from the Samail Ophiolite in Oman, I report morphological and associated chemical biosignatures preserved in these systems as a result of subsurface carbonation. As serpentinites are known to occur on Mars and potentially other planetary bodies, these deposits potentially represent high-priority targets in the exploration for past microbial life. Next, I investigated samples from Atacama Desert, Chile, to understand how evidence of life may be preserved in ancient sediments formed originally in evaporative playa lakes. Here, I describe organic geochemical and morphological evidence of life preserved within sulfate-dominated evaporite rocks from the Jurassic-Cretaceous Tonel Formation and Oligocene San Pedro Formation. Because evaporative lakes are considered to have been potentially widespread on Mars, these deposits may represent additional key targets to search for evidence of past life. In the final chapter, I describe the fossilization potential of surficial carbonates by investigating Crystal Geyser, an active cold spring environment. Here, carbonate minerals precipitate rapidly in the presence of photosynthetic microbial mat communities. I describe how potential biosignatures are initially captured by mineralization, including cell-like structures and microdigitate stromatolites. However, these morphological signatures quickly degrade owing to diagenetic dissolution and recrystallization reactions, as well as textural coarsening that homogenizes the carbonate fabric. Overall, my dissertation underscores the complexity of microbial fossilization and highlights chemically-precipitating environments that may serve as high-priority targets for astrobiological exploration.
ContributorsZaloumis, Jonathan (Author) / Farmer, Jack D (Thesis advisor) / Garcia-Pichel, Ferran (Committee member) / Trembath-Reichert, Elizabeth (Committee member) / Ruff, Steven W (Committee member) / Shock, Everett L (Committee member) / Arizona State University (Publisher)
Created2021
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Animals use diverse signal types (e.g. visual, auditory) to honestly advertise their genotypic and/or phenotypic quality to prospective mates or rivals. Behavioral displays and other dynamically updateable signals (e.g. songs, vibrations) can reliably reveal an individual’s quality in real-time, but it is unclear whether more fixed traits like feather coloration,

Animals use diverse signal types (e.g. visual, auditory) to honestly advertise their genotypic and/or phenotypic quality to prospective mates or rivals. Behavioral displays and other dynamically updateable signals (e.g. songs, vibrations) can reliably reveal an individual’s quality in real-time, but it is unclear whether more fixed traits like feather coloration, which is often developed months before breeding, still reveal an individual’s quality at the time of signal use. To address this gap, we investigated if various indices of health and condition – including body condition (residual body mass), poxvirus infection, degree of habitat urbanization, and circulating levels of ketones, glucose, vitamins, and carotenoids – were related to the expression of male plumage coloration at the start of the spring breeding season in wild male house finches (Haemorhous mexicanus), a species in which many studies have demonstrated a link between plumage redness and the health and condition of individuals at the time the feathers are grown in late summer and autumn. We found that, at the time of pair formation, plumage hue was correlated with body condition, such that redder males were in better condition (i.e. higher residual mass). Also, as in previous studies, we found that rural males had redder plumage; however, urban males had more saturated plumage. In sum, these results reveal that feather coloration developed long before breeding still can be indicative to choosy mates of a male’s current condition and suggest that females who prefer to mate with redder males may also gain proximate material benefits (e.g. better incubation provisioning) by mating with these individuals in good current condition.

ContributorsDepinto, Kathryn (Author) / McGraw, Kevin (Thesis director) / Sweazea, Karen (Committee member) / Webb, Emily (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / Department of Psychology (Contributor)
Created2021-12
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Bioindicators of wildlife health are useful tools for studying the viability of various organisms and populations, and can include a range of phenotypic variables, such as behavior, body size, and physiological parameters, such as circulating hormones and nutrients. Few studies have investigated the utility of total plasma protein as a

Bioindicators of wildlife health are useful tools for studying the viability of various organisms and populations, and can include a range of phenotypic variables, such as behavior, body size, and physiological parameters, such as circulating hormones and nutrients. Few studies have investigated the utility of total plasma protein as a predictor of environmental or nutritional variation among birds, as well as variation across different seasons and life-history stages. Here I examined relationships between plasma protein and season, urbanization, sex, body condition, molt status, and disease state in house finches (Haemorhous mexicanus). I sampled blood from house finches across three seasons (winter, summer and fall 2021) and measured plasma protein levels using a Bradford assay. I also collected data including condition, sex, and poxvirus infection state at capture, as well as fecal samples to assess gut parasitism (coccidiosis). During the fall season I also estimated molt status, as number of actively growing feathers. I found circulating plasma protein concentration to be lower in the fall during molt than during winter or summer. I also found a significant relationship between circulating protein levels and capture site, as well as novel links to molt state and pox presence, with urban birds, those infected with pox, and those in more intense molt having higher protein levels. My results support the hypotheses that plasma protein concentration can be indicative of a bird’s body molt (which demands considerable protein for feather synthesis) and degree of habitat urbanization, although future work is needed to determine why protein levels were higher in virus-infected birds.

ContributorsDrake, Dean (Author) / McGraw, Kevin (Thesis director) / Sweazea, Karen (Committee member) / Jackson, Daniel (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2022-05