Matching Items (97)
Description
Dissolved organic matter (DOM) can have numerous effects on the water chemistry and the biological life within an aquatic system with its wide variety of chemical structures and properties. The composition of the dissolved carbon can be estimated by utilizing the fluorescent properties of some DOM such as aromatic amino acids and humic material. This experiment was used to observe how organic matter could influence hydrothermal systems, such as Sylvan Springs in Yellowstone National Park, USA. Using optical density at 600 nm (OD 600), excitation-emission matrix spectra (EEMS), and Illumina sequencing methods (16S rRNA gene sequencing), changes in dissolved organic matter (DOM) were observed based on long term incubation at 84ºC and microbial influence. Four media conditions were tested over a two-month duration to assess these changes: inoculated pine needle media, uninoculated pine needle media, inoculated yeast extract media, and uninoculated yeast extract media. The inoculated samples contained microbes from a fluid and sediment sample of Sylvan Spring collected July 23, 2018. Absorbance indicated that media containing pine needle broth poorly support life, whereas media containing yeast extract revealed a positive increase in growth. Excitation-Emission Matrix Spectra of the all media conditions indicated changes in DOM composition throughout the trial. There were limited differences between the inoculated and uninoculated samples suggesting that the DOM composition change in this study was dominated by the two-month incubation at 84ºC more than biotic processes. Sequencing performed on a sediment sample collected from Sylvan Spring indicated five main order of prokaryotic phyla: Aquificales, Desulfurococcales, Thermoproteales, Thermodesulfobacteriales, and Crenarchaeota. These organisms are not regarded as heterotrophic microbes, so the lack of significant biotic changes in DOM could be a result of these microorganisms not being able to utilize these enrichments as their main metabolic energy supply.
ContributorsKnott, Nicholas Joseph (Author) / Shock, Everett (Thesis director) / Hartnett, Hilairy (Committee member) / Till, Christy (Committee member) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Callithrix penicillata, also known as the Black-tufted marmoset primarily lives in the Brazilian highlands and has had little research conducted on it. For this project I performed a genome curation on the newly assembled genome of this species. The scaffolds obtained by the Dovetail Genomics reads were organized and labeled into chromosomes using the 2014 Callithrix jacchus genome as a reference. Then, using that same genome as a reference, 13 of the chromosomes were reverse complimented to be continuous with the 2014 Callithrix jacchus genome. The N50 statistics of the assembly were calculated and found to be 124 Mb. Quality scores were run for the final genome using referee and visualized with a bar plot, with 99% of sites scoring above 0. Heterozygosity was also calculated and found to be 0.3%. Finally, the final version of the genome was visually compared to the 2017 Callithrix jacchus genome and the GRCh38 human genome. This genome was submitted to the NCBIs database to await further approval.
ContributorsJohnson, Joelle Genevieve (Author) / Cartwright, Reed (Thesis director) / Stone, Anne (Committee member) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-12
Description
Since its discovery in 1524, many people have characterized the vermiform appendix. Charles Darwin considered the human appendix to be a vestige and a useless structure. Others at the time opposed this hypothesis. However, Darwin's hypothesis became prevalent one until recently when there became a renewed interest in the appendix because of advancements in microscopes, knowledge of the immune system, and phylogenetics. In this review, I will argue that the vermiform appendix, although still not completely understood, has important functions. First, I will give the anatomy of the appendix. I will discuss the comparative anatomy between different animals and also primates. I will address the effects of appendicitis and appendectomy. I will give background on vestigial structures and will discuss if the appendix is a vestige. Following, I will review the evolution of the appendix. Finally, I will argue that the function of the appendix is as an immune organ, including discussion of gut-associated lymphoid tissue (GALT), development of lymphoid follicles in GALT and their comparison within different organs, Immunoglobulin A (IgA) function in the gut, biofilms as evidence that the appendix is a safe-house for beneficial bacteria, re-inoculation of the bowel, and protection against recurring infection. I will conclude with future studies that should be conducted to further our understanding of the vermiform appendix.
ContributorsPrestwich, Shelby Elizabeth (Author) / Cartwright, Reed (Thesis director) / Lynch, John (Committee member) / Furstenau, Tara (Committee member) / School of Geographical Sciences and Urban Planning (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Finding life beyond Earth could change our understanding of life and habitability. The best place to look for life beyond Earth is Jupiter's moon, Europa. It has been estimated Europa may have a liquid, salt-water subsurface with 2 to 3 times the volume of all Earth's oceans. Knowing that all life requires water, it is in our best interest to explore Europa. This thesis explored the plausibility of life on Europa in four of its environments: on the surface, under the ice shell, in the liquid subsurface, and at the bottom of the liquid subsurface. Each of these environments were defined from science literature and compared to known Earth analogs. Europa's surface is not likely to support life, as there is not liquid water present. There is also extremely high radiation bombardment and extremely low surface temperatures that are estimated to be well out of the range for supporting life. It is more plausible that life could be under Europa's ice shell than on the surface. Under the surface, radiation exposure dramatically reduces. Researchers have found organisms on Earth that can live in similar environments as Europa's ice as well. These organisms require some interaction with liquid water though. Uncertainties about Europa's ice shell thickness and radiation load per depth it experiences, as well as there being limited research on organisms in ice environments, hinder us from definitively assessing the plausibility of life under the surface. The best environment on Europa to look for life on Europa is the subsurface. There remain a lot of uncertainties about the subsurface, however, that make it difficult to assess the plausibility of finding life. These uncertainties include its depth, water activity, salinity, temperature, pressure, and structure. This subsurface may be suitable for life, but until we can further understand the environment of the subsurface, we cannot make definite conclusions. As for assessing the plausibility of life at the bottom of Europa's subsurface, there is not much we know about this environment either. It has been suggested there may be hydrothermal vents, but no evidence has either supported or rejected this idea. Without a clear understanding of the environment at the bottom of the subsurface, the plausibility of life here cannot be definitively answered. It is apparent we need to further study Europa. In particular, we need to focus on understanding the subsurface. When the subsurface is better defined, we can better assess the plausibility of life being present. Fortunately, both NASA and the ESA are currently planning missions to Europa that are scheduled to launch in the 2020s.
ContributorsHoward, Cheyenne Whiffen (Author) / Farmer, Jack (Thesis director) / Shock, Everett (Committee member) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
With the rising data output and falling costs of Next Generation Sequencing technologies, research into data compression is crucial to maintaining storage efficiency and costs. High throughput sequencers such as the HiSeqX Ten can produce up to 1.8 terabases of data per run, and such large storage demands are even more important to consider for institutions that rely on their own servers rather than large data centers (cloud storage)1. Compression algorithms aim to reduce the amount of space taken up by large genomic datasets by encoding the most frequently occurring symbols with the shortest bit codewords and by changing the order of the data to make it easier to encode. Depending on the probability distribution of the symbols in the dataset or the structure of the data, choosing the wrong algorithm could result in a compressed file larger than the original or a poorly compressed file that results in a waste of time and space2. To test efficiency among compression algorithms for each file type, 37 open-source compression algorithms were used to compress six types of genomic datasets (FASTA, VCF, BCF, GFF, GTF, and SAM) and evaluated on compression speed, decompression speed, compression ratio, and file size using the benchmark test lzbench. Compressors that outpreformed the popular bioinformatics compressor Gzip (zlib -6) were evaluated against one another by ratio and speed for each file type and across the geometric means of all file types. Compressors that exhibited fast compression and decompression speeds were also evaluated by transmission time through variable speed internet pipes in scenarios where the file was compressed only once or compressed multiple times.
ContributorsHowell, Abigail (Author) / Cartwright, Reed (Thesis director) / Wilson Sayres, Melissa (Committee member) / Taylor, Jay (Committee member) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Many bacteria actively import environmental DNA and incorporate it into their genomes. This behavior, referred to as transformation, has been described in many species from diverse taxonomic backgrounds. Transformation is expected to carry some selective advantages similar to those postulated for meiotic sex in eukaryotes. However, the accumulation of loss-of-function alleles at transformation loci and an increased mutational load from recombining with DNA from dead cells create additional costs to transformation. These costs have been shown to outweigh many of the benefits of recombination under a variety of likely parameters. We investigate an additional proposed benefit of sexual recombination, the Red Queen hypothesis, as it relates to bacterial transformation. Here we describe a computational model showing that host-pathogen coevolution may provide a large selective benefit to transformation and allow transforming cells to invade an environment dominated by otherwise equal non-transformers. Furthermore, we observe that host-pathogen dynamics cause the selection pressure on transformation to vary extensively in time, explaining the tight regulation and wide variety of rates observed in naturally competent bacteria. Host-pathogen dynamics may explain the evolution and maintenance of natural competence despite its associated costs.
ContributorsPalmer, Nathan David (Author) / Cartwright, Reed (Thesis director) / Wang, Xuan (Committee member) / Sievert, Chris (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Mammary gland development in humans during puberty involves the enlargement of breast tissue, but this is not true in non-human primates. To identify potential causes of this difference, I examined variation in substitution rates across genes related to mammary development. Genes undergoing purifying selection show slower-than-average substitution rates, while genes undergoing positive selection show faster rates. These may be related to the difference between humans and other primates. Three genes were found to be accelerated were FOXF1, IGFBP5, and ATP2B2, but only the latter one was found in humans and it seems unlikely that it would be related to the differences between mammary gland development at puberty between humans and non-human primates.
ContributorsArroyo, Diana (Author) / Cartwright, Reed (Thesis director) / Wilson Sayres, Melissa (Committee member) / Schwartz, Rachel (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Yellowstone National Park has a vibrant variety of flora, fauna, and hydrothermal systems all collected together in one large and complex system. Studies have been conducted for at least several decades in order to make sense of this system in ways that may be relevant to other similar geologies around the world. The latest update in this ever-ongoing study involves the collection and analysis of water samples from 2016. These samples have been analyzed for conductivity, pH, temperature, dissolved organic carbon, dissolved inorganic carbon, carbon isotopes, dissolved oxygen, ferrous iron, sulfide, silica, and more. While not many trends were found in this data in regards to dissolved organic carbon values, this is a substantial addition to a growing body of information that could yield more impressive information in times to come. In addition, factors that have yet to analyzed for this 2016 data, such as concentrations of metals and metalloids, may provide some insights when put through a chloride vs sulfate framework to separate out different reaction regions.
ContributorsDoan, Cuong Le (Author) / Shock, Everett (Thesis director) / Gould, Ian (Committee member) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
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
Description
I present results of field and laboratory experiments investigating the habitability of one of Earth’s driest environments: the Atacama Desert. This Desert, along the west coast of South America spanning Perú and Chile, is one of the driest places on Earth and has been exceedingly arid for millions of years. These conditions create the perfect natural laboratory for assessing life at the extremes of habitability. All known life needs water; however, the extraordinarily dry Atacama Desert is inhabited by well-adapted microorganisms capable of colonizing this hostile environment. I show field and laboratory evidence of an environmental process, water vapor adsorption, that provides a daily, sustainable input of water into the near (3 - 5 cm) subsurface through water vapor-soil particle interactions. I estimate that this water input may rival the yearly average input of rain in these soils (~2 mm).
I also demonstrate, for the first time, that water vapor adsorption is dependent on mineral composition via a series of laboratory water vapor adsorption experiments. The results of these experiments provide evidence that mineral composition, and ultimately soil composition, measurably and significantly affect the equilibrium soil water content. This suggests that soil microbial communities may be extremely heterogeneous in distribution depending on the distribution of adsorbent minerals.
Finally, I present changes in biologically relevant gasses (i.e., H2, CH4, CO, and CO2) over long-duration incubation experiments designed to assess the potential for biological activity in soils collected from a hyperarid region in the Atacama Desert. These long-duration experiments mimicked typical water availability conditions in the Atacama Desert; in other words, the incubations were performed without condensed water addition. The results suggest a potential for methane-production in the live experiments relative to the sterile controls, and thus, for biological activity in hyperarid soils. However, due to the extremely low biomass and extremely low rates of activity in these soils, the methods employed here were unable to provide robust evidence for activity. Overall, the hyperarid regions of the Atacama Desert are an important resource for researchers by providing a window into the environmental dynamics and subsequent microbial responses near the limit of habitability.
ContributorsGlaser, Donald M (Author) / Hartnett, Hilairy E (Thesis advisor) / Anbar, Ariel (Committee member) / Shock, Everett (Committee member) / Arizona State University (Publisher)
Created2022