Archaea Commons^™

Eco-Interoception: What Plants, Fungi And Protista Have Taught My Body, Sara Riley Dotterer

Art Theses and Dissertations

To me, ecology is the relational, full-body awareness that I am made up of and deeply connected to everything around me; and for better or worse, this is reciprocal. I form ecotones, an ecological transitional zone between two ecosystems, with the world around me. I use this ecotonal lens to blur binaries and dissolve boundaries between me and the world “outside my body.” During my Masters of Fine Arts at Southern Methodist University, I have continuously explored and represented the lives of various more-than-human species outside of my body, including plants, fungi and protista through an ecotonal lens. Although these …

Metagenomes From High-Temperature Chemotrophic Systems Reveal Geochemical Controls On Microbial Community Structure And Function, William P. Inskeep, Douglas B. Rusch, Zackary J. Jay, Markus J. Herrgard, Mark A. Kozubal, Toby H. Richardson, Richard E. Macur, Natsuko Hamamura, Ryan Dem. Jennings, Bruce W. Fouke, Anna-Louise Reysenbach, Frank Roberto, Mark Young, Ariel Schwartz, Eric S. Boyd, Jonathan H. Badger, Eric J. Mathur, Alice C. Ortmann, Mary Bateson, Gill Geesey

Biology Faculty Publications and Presentations

The Yellowstone caldera contains the most numerous and diverse geothermal systems on Earth, yielding an extensive array of unique high-temperature environments that host a variety of deeply-rooted and understudied Archaea, Bacteria and Eukarya. The combination of extreme temperature and chemical conditions encountered in geothermal environments often results in considerably less microbial diversity than other terrestrial habitats and offers a tremendous opportunity for studying the structure and function of indigenous microbial communities and for establishing linkages between putative metabolisms and element cycling. Metagenome sequence (14-15,000 Sanger reads per site) was obtained for five hightemperature (>65°C) chemotrophic microbial communities sampled from …

Isolation Of A Ubiquitous Obligate Thermoacidophilic Archaeon From Deep-Sea Hydrothermal Vents, Anna-Louise Reysenbach, Yitai Liu, Amy B. Banta, Terry J. Beveridge, Julie D. Kirshtein, Stefan Schouten, Margaret K. Tivey, Karen L. Von Damm, Mary A. Voytek

Biology Faculty Publications and Presentations

Deep-sea hydrothermal vents are important in global biogeochemical cycles, providing biological oases at the sea floor that are supported by the thermal and chemical flux from the Earth's interior. As hot, acidic and reduced hydrothermal fluids mix with cold, alkaline and oxygenated sea water, minerals precipitate to form porous sulphide–sulphate deposits. These structures provide microhabitats for a diversity of prokaryotes that exploit the geochemical and physical gradients in this dynamic ecosystem. It has been proposed that fluid pH in the actively venting sulphide structures is generally low (pH < 4.5), yet no extreme thermoacidophile has been isolated from vent deposits. Culture-independent surveys based on ribosomal RNA genes from deep-sea hydrothermal deposits have identified a widespread euryarchaeotal lineage, DHVE2 (deep-sea hydrothermal vent euryarchaeotic 2) Despite the ubiquity and apparent deep-sea endemism of DHVE2, cultivation of this group has been unsuccessful and thus its metabolism remains a mystery. Here we report the isolation and cultivation of a member of the DHVE2 group, which is an obligate thermoacidophilic sulphur- or iron-reducing heterotroph capable of growing from pH 3.3 to 5.8 and between 55 and 75 °C. In addition, we demonstrate that this isolate constitutes up to 15% of the archaeal population, providing evidence that thermoacidophiles may be key players in the sulphur and iron cycling at deep-sea vents.

Rearrangement Of The Rna Polymerase Subunit H And The Lower Jaw In Archaeal Elongation Complexes, Sebastian Grünberg, Christoph Reich, Mirijam E. Zeller, Michael S. Bartlett, Michael Thomm

Biology Faculty Publications and Presentations

The lower jaws of archaeal RNA polymerase and eukaryotic RNA polymerase II include orthologous subunits H and Rpb5, respectively. The tertiary structure of H is very similar to the structure of the C-terminal domain of Rpb5, and both subunits are proximal to downstream DNA in pre-initiation complexes. Analyses of reconstituted euryarchaeal polymerase lacking subunit H revealed that H is important for open complex formation and initial transcription. Eukaryotic Rpb5 rescues activity of the ΔH enzyme indicating a strong conservation of function for this subunit from archaea to eukaryotes. Photochemical cross-linking in elongation complexes revealed a striking structural rearrangement of RNA …

Taxis Toward Hydrogen Gas By Methanococcus Maripaludis, Kristen A. Brileya, James M. Connolly, Carey Downey, Robin Gerlach, Matthew W. Fields

Biology Faculty Publications and Presentations

Knowledge of taxis (directed swimming) in the Archaea is currently expanding through identification of novel receptors, effectors, and proteins involved in signal transduction to the flagellar motor. Although the ability for biological cells to sense and swim toward hydrogen gas has been hypothesized for many years, this capacity has yet to be observed and demonstrated. Here we show that the average swimming velocity increases in the direction of a source of hydrogen gas for the methanogen, Methanococcus maripaludis using a capillary assay with anoxic gas-phase control and time-lapse microscopy. The results indicate that a methanogen couples motility to hydrogen concentration …

Site Tolerance Of The Rada Intein, Chase Taul, Christopher Lennon Dr

Honors College Theses

Inteins (intervening proteins) invade genes at the DNA level and splice out at the protein level. Once thought of as only a parasitic type of a mobile genetic element, recent work suggests a mutualistic relationship has formed in some cases within bacterial and archaeal hosts. After translation, a precursor protein is formed with the intein between two exteins. The intein is catalytic and can excise itself out through protein splicing. Intein insertion is biased towards the active site of the protein and is thought to cause inactivation of the host protein prior to splicing. Intein splicing is responsive to a …

Hyporheic Zone Hydrodynamics, Biogeochemistry, And Microbial Community Distributions For The San Saba River, Texas, Ethan Sweet

Masters Theses

The hyporheic zone (HZ) plays a crucial role in riparian ecosystems by providing essential habitat and contributing to biogeochemical cycling. Although microorganisms are known to control most of the biogeochemical processes occurring in the HZ, past investigations of microbial communities within the HZ have been limited in scope. This study examines changes in geochemical processes, associated microbial communities, and other environmental factors at large and small scales within the HZ of the San Saba River in Central Texas. Pool-riffle sequences spanned approximately 228.6 to 22.4 kilometers upstream from the confluence of the San Saba and Colorado Rivers. Up to five …

Justification For The Biological Foundation Of Methane On Mars: Methanogens’ Capacity To Metabolize On Montmorillonite Clay And Basalt, Ashley Ezeldin

Biological Sciences Undergraduate Honors Theses

The possibility of extraterrestrial life, particularly on Mars, remains a compelling question in astrobiology. Mars' harsh atmospheric conditions, dominated by carbon dioxide and extreme cold, prevent the survival of aerobic species. However, it still leaves the possibility of methanogens, an anaerobic species that can survive in extreme conditions, to inhabit this planet. Due to the discovery of methane on Mars, it is possible that methanogens may live and grow in the subsurface of this planet.

For this experiment, basalt and montmorillonite clay were chosen as substrates because they are believed to be found in the composition of Mars's subsurface. Methane, …