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Functional Morphology, Biomechanics, And Evolution Of Ruminant Mammals, Abby Vander Linden Oct 2021

Functional Morphology, Biomechanics, And Evolution Of Ruminant Mammals, Abby Vander Linden

Doctoral Dissertations

Ruminant mammals, including the families Bovidae, Cervidae, Tragulidae, Moschidae, Antilocapridae, and Giraffidae, display incredible past and present diversity in morphology, ecology, and behavior. They inhabit an impressive range of environments across North and South America, Europe, Asia, and Africa, and compel the fascination of naturalists and researchers alike with their charismatic social behavior and conspicuous cranial appendages. I explore the drivers and consequences of this spectacular diversity through a comparative morphological framework, biomechanical modeling approaches, and semi-parametric and likelihood-based methods for estimating state-dependent diversification rates across the ruminant phylogeny. Together, these investigations provide evidence for adaptation via correlated evolution of …


The Effect Of Disturbance And Invasion On Fungal And Plant Communities Over An Elevational Gradient, Adam N. Trautwig Oct 2021

The Effect Of Disturbance And Invasion On Fungal And Plant Communities Over An Elevational Gradient, Adam N. Trautwig

Doctoral Dissertations

High-elevation ecosystems are at risk of disruption from the future effects of climate change. Sub-alpine meadows are a source of unique plant populations, intraspecific variation of elevationally extreme populations, and vital sources of fresh water resources. We evaluated the whole fungal communities, arbuscular mycorrhizal fungal (AMF) communities, plant communities, and edaphic variables of sub-alpine meadows in undisturbed, disturbed, and disturbed with a non-native member of the Brassicaceae (Thlaspi arvense) plots. In conjunction with measuring the effects of disturbance on native communities we conducted potting experiments on a dominant grass of sub-alpine meadows (Festuca thurberi). We also …


Understanding How Camkii Holoenzyme Dynamics Facilities Activation-Triggered Subunit Exchange, Ana P. Torres-Ocampo Oct 2021

Understanding How Camkii Holoenzyme Dynamics Facilities Activation-Triggered Subunit Exchange, Ana P. Torres-Ocampo

Doctoral Dissertations

Long-term memory and learning are still poorly understood from a molecular and cellular standpoint. Ca2+/calmodulin-dependent protein kinase II (CaMKII) is an oligomeric kinase that is involved in this remarkable process. However, the molecular details of its specific roles in these processes remains elusive. CaMKII activation-triggered subunit exchange presents a novel possible mechanism involved in long-term memory and learning by exchanging active subunits with other CaMKIIs. CaMKII subunit exchange also shows that exchanged CaMKIIs spread their phosphorylation state to newly synthesized CaMKIIs. This provides a long-lasting signal that might possibly be involved in long-term memory by escaping a cell’s …


Mechanistic Insights Into Diverse Protease Adaptor Functions, Nathan J. Kuhlmann Oct 2021

Mechanistic Insights Into Diverse Protease Adaptor Functions, Nathan J. Kuhlmann

Doctoral Dissertations

Protein degradation is an essential cellular process that helps maintain proper homeostasis. The ClpXP protease broadly regulates bacterial development and quality control during the cell cycle. The range and order of substrates that ClpXP degrades during the cell cycle is dictated by 3 accessory proteins, which are known as adaptors. This thesis will elaborate on how dimerization tightly regulates the stability and activity of the adaptor protein at the center of this hierarchy, RcdA, and show how this affects normal cellular processes in Caulobacter crescentus. I will discuss the mechanism by which dimerization limits RcdA activity and how the dimerization …


Attitudes And Interactions Of Indigenous And Non-Indigenous People With Wildlife In The Northern Talamanca Mountains Of Costa Rica, Carolina Saenz-Bolaños Oct 2021

Attitudes And Interactions Of Indigenous And Non-Indigenous People With Wildlife In The Northern Talamanca Mountains Of Costa Rica, Carolina Saenz-Bolaños

Doctoral Dissertations

In this study I investigated wildlife and human use of landscapes in the northern Talamanca Mountains of Costa Rica (Pacuare-Barbilla sector), including three contiguous protected areas (a national park, a forest reserve, and an indigenous territory), as well as surrounding unprotected areas. I describe and compare perceptions of wildlife by different social actors in the Pacuare-Barbilla sector, collecting information with a questionnaire as an instrument. I also inventoried and monitored the abundance and distribution of a variety of wildlife species occurring throughout the area using camera traps. The species with greater abundance or only occurrence in the national park were …


Antibiotic Sensitivity Testing Of Foodborne Bacteria Using Surface-Enhanced Raman Spectroscopy, Joshua Gukowsky Oct 2021

Antibiotic Sensitivity Testing Of Foodborne Bacteria Using Surface-Enhanced Raman Spectroscopy, Joshua Gukowsky

Doctoral Dissertations

The spread of antibiotic resistant bacteria around the world has become a major public health issue, and it is essential that effective detection methods exist for identifying these organisms and preventing them from spreading throughout our food systems and into the environment. The goal of this research is to develop a novel analytical procedure that is capable of easily identifying antibiotic resistance in bacterial samples, and also provides more information about the biochemical characteristics of the bacteria and their responses to antibiotic exposure. Surface-enhanced Raman Spectroscopy (SERS), an analytical technique that uses light scattering to produce a spectrum based on …


Investigating The Developmental Impacts Of 3,3’-Dichlorobiphenyl (Pcb-11) In Zebrafish (Danio Rerio), Monika A. Roy Oct 2021

Investigating The Developmental Impacts Of 3,3’-Dichlorobiphenyl (Pcb-11) In Zebrafish (Danio Rerio), Monika A. Roy

Doctoral Dissertations

The environmental pollutant 3,3’-dichlorobiphenyl (PCB-11) is a lower-chlorinated polychlorinated biphenyl (PCB) congener present in air and water samples. Both PCB-11 and its metabolite, 4-PCB-11-Sulfate, are detected in humans, including in pregnant women. The work conducted for this dissertation takes a developmental toxicology approach and uses zebrafish (Danio rerio) to investigate PCB-11’s potential impacts to the liver and pancreas. Chapter 1 introduces PCBs and the current knowledge gaps. Chapter 2 investigates PCB-11 interactions in short-term 4-day exposures with the Aryl hydrocarbon receptor (Ahr) pathway in both 0-20 mM individual and mixture exposures with other Ahr agonists. In Chapter 3, …


Data Access, Distribution Models, And Stable Isotopes: Merging Approaches To Improve Bear Distribution Estimates And Bear Carnivory For Conservation, Nereyda Falconi Oct 2021

Data Access, Distribution Models, And Stable Isotopes: Merging Approaches To Improve Bear Distribution Estimates And Bear Carnivory For Conservation, Nereyda Falconi

Doctoral Dissertations

My dissertation aims to contribute to the knowledge of Andean bears in Peru. The Andean bear (Tremarctos ornatus) is the sole bear species in south America. The lack of knowledge on different aspects of Andean bear ecology, biogeography, and abundance patterns hinders current conservation efforts for the species. I compiled Andean bear occurrence records in Peru with collaboration from many colleagues and created an open-access database at the GBIF data repository. Next, I modeled the distribution of Andean bear within Peru and compared estimates including and excluding unpublished records. I found that models combining published and unpublished records …


On Spatiotemporal Connectivity Dynamics: Perspectives From A Naturally Fragmented Metapopulation, Joseph Drake Oct 2021

On Spatiotemporal Connectivity Dynamics: Perspectives From A Naturally Fragmented Metapopulation, Joseph Drake

Doctoral Dissertations

Connectivity has quickly become a central tenet of ecological research, frequently evoked for conservation research and management activities. However, the concept of connectivity has proliferated into many forms for many different perspectives. Generally said, population distributions, demography, landscape, and dispersal all contribute to connectivity in a meaningful way. While great progress has been made in increasing realism in connectivity, one component seemed to stand out as being underappreciated: the role of population dynamics in the application of landscape connectivity. I began to acquire an appreciation for how common modeling approaches make assumptions about these core components of connectivity. In Chapter …


Monitoring Mammals At Multiple Scales: Case Studies From Carnivore Communities, Kadambari Devarajan Oct 2021

Monitoring Mammals At Multiple Scales: Case Studies From Carnivore Communities, Kadambari Devarajan

Doctoral Dissertations

Carnivores are distributed widely and threatened by habitat loss, poaching, climate change, and disease. They are considered integral to ecosystem function through their direct and indirect interactions with species at different trophic levels. Given the importance of carnivores, it is of high conservation priority to understand the processes driving carnivore assemblages in different systems. It is thus essential to determine the abiotic and biotic drivers of carnivore community composition at different spatial scales and address the following questions: (i) What factors influence carnivore community composition and diversity? (ii) How do the factors influencing carnivore communities vary across spatial and temporal …


Role Of The Prefrontal Cortex In Reward Seeking Behaviors, Jessica Caballero-Feliciano Oct 2021

Role Of The Prefrontal Cortex In Reward Seeking Behaviors, Jessica Caballero-Feliciano

Doctoral Dissertations

Disorders associated with compulsive seeking of rewards, like binge-eating, are associated with abnormalities of the prefrontal cortex in humans, which is analogous to the prelimbic (PL) and infralimbic (IL) subregions of the medial prefrontal cortex (mPFC) in rodents. Although studies have examined the role of the mPFC in drug seeking behaviors, studies examining natural reward seeking behaviors (i.e. food and sucrose) are often unclear and contradictory. This dissertation aims to characterize the role of the PL and IL mPFC in operant sucrose seeking behaviors. We used pharmacological and chemogenetic tools to selectively inactivate the PL, IL and PL-nucleus accumbens (NAc) …


Diversity And Evolution Of Human Eccrine Sweat Gland Density, Andrew W. Best Oct 2021

Diversity And Evolution Of Human Eccrine Sweat Gland Density, Andrew W. Best

Doctoral Dissertations

Human eccrine density is highly derived. However, little is known about contemporary variation in this trait, what shapes it, and how it influences heat dissipation. This project explores 3 questions: 1) Is variation in functional eccrine density (FED) explained by childhood climate? 2) Is this variation patterned by geographic ancestry? 3) Is variation in FED associated with differences in heat dissipation capacity? We measured FED and sweat production in 6 body areas via pharmacological stimulation and impressions of sweating skin in 72 participants. Childhood climate variables were taken from the WorldClim database and geographic ancestry was estimated with 23andMe tests. …


The Characterization Of Traits Associated With Freezing Tolerance In Perennial Ryegrass, Rachael Preston Bernstein Oct 2021

The Characterization Of Traits Associated With Freezing Tolerance In Perennial Ryegrass, Rachael Preston Bernstein

Doctoral Dissertations

Plants are constantly subjected to adverse environmental conditions that alter their growth and productivity, with an estimation that approximately 50% of annual average crop yields are reduced due to abiotic stresses. Freezing stress causes desiccation and ice damage in plants and is becoming more important as temperatures and unpredictable weather patterns increase. Normally, plants acclimate to cold temperatures as winter approaches and deacclimate as temperatures warm in the spring. Cold acclimation in fall is required for plants to build up their cellular defenses against desiccation and intracellular ice formation, while deacclimation is the process in which plants metabolize protective compounds …


Discovering Mechanisms Driving Adaptive Evolution In The Cross-Kingdom Fungal Pathogen Fusarium Oxysporum, Dilay Hazal Ayhan Oct 2021

Discovering Mechanisms Driving Adaptive Evolution In The Cross-Kingdom Fungal Pathogen Fusarium Oxysporum, Dilay Hazal Ayhan

Doctoral Dissertations

Fusarium oxysporum is a cross-kingdom pathogenic fungus that can cause vascular wilt disease in many economically important plants and local or disseminated infections in humans. Although it lacks a sexual stage in its life cycle, F. oxysporum can adapt to a wide range of hosts because of accessory chromosomes (ACs) which are enriched in host-specific genes and repeat content. This dissertation investigates the mechanisms that drive the adaptive evolution in the cross-kingdom pathogen F. oxysporum using comparative genomics and an experimental evolution approach. The first chapter compares phenotypes and genomes of a plant pathogenic isolate F. oxysporum f. sp. lycopersici …


Mechanisms Of Mitotic Checkpoint Silencing By The Disordered Kinetochore Protein Spc105, Margaux Audett Oct 2021

Mechanisms Of Mitotic Checkpoint Silencing By The Disordered Kinetochore Protein Spc105, Margaux Audett

Doctoral Dissertations

The kinetochore protein Spc105R (DmSpc105R) is a large intrinsically disordered protein (IDP) that recruits spindle assembly checkpoint (SAC) proteins and is required for SAC signaling in a conserved manner. Chromosome biorientation satisfies the SAC and while it has been proposed that SAC satisfaction may require the establishment of stable kinetochore-MT (KT-MT) attachments and tension generation, the question of whether tension directly regulates SAC signaling is unresolved and controversial. Here we present data in support of Spc105R as a tension-sensing IDP that directly regulates checkpoint protein localization and signaling independent of the establishment of stable KT-MT attachments. The N-terminus of DmSpc105R …


Amyloidogenesis Of Β-2-Microglobulin Studied By Mass Spectrometry And Covalent Labeling, Blaise G. Arden Oct 2021

Amyloidogenesis Of Β-2-Microglobulin Studied By Mass Spectrometry And Covalent Labeling, Blaise G. Arden

Doctoral Dissertations

Amyloid-forming proteins are implicated in a number of debilitating diseases. While many amyloid-forming proteins are well studied, the early stages of amyloidosis are still not well understood on a molecular level. Covalent labeling, combined with mass spectrometry (CL-MS), is uniquely well suited to provide molecular-level insight into the factors governing the early stages of amyloidosis. This dissertation leverages CL-MS techniques to examine the early stages of β-2-microglobulin (β2m) amyloidosis. β2m is the protein that forms amyloids in the condition known as dialysis-related amyloidosis. An automated CL-MS technique that uses dimethyl(2-hydroxy-5-nitrobenzyl) sulfonium bromide as a labeling reagent was developed and used …


Primary Kinetic Isotope Effect For Substrate Hydroxylation And Iron Binding Regulation In Factor Inhibiting Hif-1, Michael A. Mingroni Oct 2021

Primary Kinetic Isotope Effect For Substrate Hydroxylation And Iron Binding Regulation In Factor Inhibiting Hif-1, Michael A. Mingroni

Doctoral Dissertations

The hypoxic response is a vast and complex system, delicately designed through evolution to allow our tissues to rapidly adapt and survive fluctuations in pO2. HIF1α, the master regulator of oxygen, is tightly controlled through oxygen-dependent, post-translational hydroxylation via PHD2 and FIH1.The aberrant stabilization of HIF1α is an adverse consequence of disease states, but can also occur under normoxia in the presence of ROS or in iron depletion. The extensive transcriptional network regulated by HIF1α makes the HIF pathway an attractive therapeutic target, particularly through the inhibition of the hydroxylases, PHD2 and FIH, however the active site chemistry is mechanistically …


Extracellular Polymeric Substances In Oxygenic Photogranules: Investigation Of Their Role In Photogranulation In A Hydrostatic Environment, Wenye Camilla Kuo-Dahab Sep 2021

Extracellular Polymeric Substances In Oxygenic Photogranules: Investigation Of Their Role In Photogranulation In A Hydrostatic Environment, Wenye Camilla Kuo-Dahab

Doctoral Dissertations

The purpose of this dissertation was to assess the critical role of extracellular polymeric substances (EPS) in the photogranulation of activated sludge, in a hydrostatic environment. The first section evaluates the fate and dynamics of different fractions of EPS in sludge-based photogranulation under hydrostatic conditions. The study shows that during the transformation of activated sludge into a photogranular biomass, sludge’s base-extractable proteins selectively degrade. Strong correlations between base-extracted proteins and the growth of chlorophyll a and chlorophyll a/b ratio suggest that the bioavailability of this organic nitrogen is linked with selection and enrichment of filamentous cyanobacteria under hydrostatic conditions. The …


Structural Analysis Of Protein Therapeutics By Hydrogen Deuterium Exchange And Covalent Labeling Mass Spectrometry, Catherine Yvonne Tremblay Sep 2021

Structural Analysis Of Protein Therapeutics By Hydrogen Deuterium Exchange And Covalent Labeling Mass Spectrometry, Catherine Yvonne Tremblay

Doctoral Dissertations

This dissertation focuses on the use of mass spectrometry (MS) to study therapeutic protein higher order structure (HOS) by encoding the structure into the mass of the protein. As therapeutic proteins become more common in the pharmaceutical industry, the need for methods that accurately determine their HOS has grown. Two methods applied here are hydrogen deuterium exchange (HDX) MS and diethylpyrocarbonate (DEPC) covalent labeling (CL) MS. We demonstrate how these two methods provide complementary, and sometimes synergistic, information about protein HOS. HDX/MS reports on both changes in solvent exposure and changes in protein dynamics, and as a result it can …


Improvement Of Solubility, Stability, And Bioaccessibility Of Curcumin Using Colloidal Delivery Systems, Bingjing Zheng Jul 2021

Improvement Of Solubility, Stability, And Bioaccessibility Of Curcumin Using Colloidal Delivery Systems, Bingjing Zheng

Doctoral Dissertations

Curcumin is a yellow-orange crystalline substance found in certain foods (turmeric) that is claimed to exhibit a broad range of biological activities. Its application as a nutraceutical in functional foods and beverages is often limited by its relatively low solubility in aqueous media, its chemical instability, and its low bioavailability. Recent research suggests that colloidal delivery systems can overcome these hurdles and improve the efficacy and commercial value of curcumin in the food, supplement, and pharmaceutical fields. The purpose of this research was to develop colloidal delivery systems to improve the application of curcumin as a nutraceutical in foods. First, …


Investigation On The Factors Impacting The Bioaccessibility Of Oil-Soluble Vitamins: Food Matrix Effects, Yunbing Tan Jul 2021

Investigation On The Factors Impacting The Bioaccessibility Of Oil-Soluble Vitamins: Food Matrix Effects, Yunbing Tan

Doctoral Dissertations

Food, nutrition, and pharmaceutical scientists are trying to elucidate the major factors impacting the bioavailability of macronutrients (e.g., lipids), micronutrients (e.g., vitamins), and nutraceuticals (e.g., carotenoids) so as to improve their efficacy. Currently, however, there is a limited understanding of how food matrix effects impact nutrient digestion and bioavailability. In this thesis, the impact of food matrix effects was elucidated by systematically examining the influence of several important factors (including oil type, oil concentration, droplet size, emulsifier type, and nutrient type) on lipid digestion and the bioaccessibility of hydrophobic bioactive agents. Oil-in-water emulsions were used as model …


Formation, Characterization, And Utilization Of Multilayer Nanoemulsions In Foods, Jorge L. Muriel Mundo Jun 2021

Formation, Characterization, And Utilization Of Multilayer Nanoemulsions In Foods, Jorge L. Muriel Mundo

Doctoral Dissertations

Multilayer coatings have been proposed as a promising nanotechnology for improving the performance of emulsion-based products in numerous research fields. In foods, these multilayer coatings can be used to improve the encapsulation and protection of bioactive ingredients in delivery systems during storage and passage through the gastrointestinal tract (1, 2). Therefore, there is strong interest in understanding the formation, properties, and performance of these novel coatings. Multilayer coatings are formed by layer-by-layer electrostatic deposition of oppositely charged biopolymers, such as proteins and polysaccharides. A better understanding of the formation and properties of biopolymer multilayer coatings could lead to …


Environmental Drivers Of Jaguar Distribution, Activity, And Abundance In Santa Rosa National Park, Costa Rica, Victor Montalvo Jun 2021

Environmental Drivers Of Jaguar Distribution, Activity, And Abundance In Santa Rosa National Park, Costa Rica, Victor Montalvo

Doctoral Dissertations

Jaguars (Panthera onca) are a landscape species persisting in less than 54% of their historical distribution range; thus, the understanding of abiotic and biotic environmental factors affecting ecological interactions of this top predator in seasonal ecosystems such the dry forest is crucial for their conservation. In addition to factors affecting species ecology, some methodological constraints also could affect jaguar study outcomes leading to wrong decision-making. Data gathered from available jaguar peer-reviewed literature showed that there are large number of variables and techniques used to model jaguar distribution that did not contribute substantially to descriptions of jaguar distribution. Using …


Rapid Cell Phenotyping Using Array-Based Sensors: Applications In Cancer Stem Cell Therapy And High-Content Screening, Yingying Geng Jun 2021

Rapid Cell Phenotyping Using Array-Based Sensors: Applications In Cancer Stem Cell Therapy And High-Content Screening, Yingying Geng

Doctoral Dissertations

Cell surface harbors rich information regarding the status of cell health. Being able to monitor and detect its changes in response to stimuli will provide crucial information in drug discovery, disease diagnosis, and human health. Despite the efforts and breakthroughs made possible through the specific sensing approach, there are significant challenges in extracting the information on the cell surface in a quantitative and reliable way. To address this challenge, I took the approach of array-based, hypothesis-free sensing in which the engineered sensors selectively interact with target analytes, producing a distinct pattern of response that enables analyte identification. This signature-based pattern …


Novel Approaches Towards Improved Purity In High Yield Transcription Reactions, Elvan Cavac Jun 2021

Novel Approaches Towards Improved Purity In High Yield Transcription Reactions, Elvan Cavac

Doctoral Dissertations

High yields of RNA (e.g., mRNA, gRNA, lncRNA) are routinely prepared following a two-step approach: high yield in vitro transcription using T7 RNA polymerase, followed by extensive purification using gel or chromatic methods. In high yield transcription reactions, as RNA accumulates in solution, T7 RNA polymerase rebinds and extends the encoded RNA (using the RNA as a template), resulting in a product pool contaminated with longer than desired, (partially) double stranded impurities. Current purification methods often fail to fully eliminate these impurities which, if present in therapeutics, can stimulate the innate immune response with potentially fatal consequences. This study establishes …


Pharmacological Chaperoning Of Human Lysosomal Neuraminidase 1, Di Chu May 2021

Pharmacological Chaperoning Of Human Lysosomal Neuraminidase 1, Di Chu

Doctoral Dissertations

Human lysosomal neuraminidase 1 (hNEU1) is an exo-a-sialidase which cleaves a(2-3) and a(2-6) linked sialic acids on glycoproteins in the lysosome. Deficiency of hNEU1 in the lysosome results in sialidosis, a lysosomal storage disease. Currently there is no effective treatment for sialidosis, which leads to a rising interest in discovering potential therapies. Here we presented a small molecule, α-D-N-acetylneuraminic acid (NANA), increases the protein amount and activity of both wild-type hNEU1 and three different hNEU1 mutations found in sialidosis patients in our mammalian cell system, suggesting that NANA works as a potential pharmacological chaperone for hNEU1 and provides …


Investigative Mechanisms To Exploit Caspase-Induced Apoptosis Using Polymeric Nanogels, Francesca Edith Anson May 2021

Investigative Mechanisms To Exploit Caspase-Induced Apoptosis Using Polymeric Nanogels, Francesca Edith Anson

Doctoral Dissertations

Cysteine aspartate proteases (caspases) act as the molecular scissors of cell death, disintegrating diverse cellular components necessary for survival and growth via proteolysis. Caspases are tightly regulated through a myriad of mechanisms including proteolytic processing, structural changes, post-translational modifications and metal binding. Correspondingly, cancers have evolved numerous resistance and desensitization mechanisms upstream or within the caspase pathway to avoid death signals. These mechanisms are extremely diverse and are not fully understood however, the field overwhelming suggests caspase activity and caspase inhibition antagonism to be critical for efficacious cancer therapies. Accordingly, exploiting the role of caspases in apoptosis has become an …


Caprine Γδ T Cell Biology, Alehegne W. Yirsaw Apr 2021

Caprine Γδ T Cell Biology, Alehegne W. Yirsaw

Doctoral Dissertations

CAPRINE gd T CELL BIOLOGY AUGUST 2020 ALEHEGNE W YIRSAW, DVM, ADDIS ABABA UNIVERSITY, ETHIOPIA MSC., ADDIS ABABA UNIVERSITY, ETHIOPIA PHD., UNIVERSITY OF MASSACHUSETTS AMHERST DIRECTED BY: PROFESSOR CYNTHIA L BALDWIN Goats are important food animals and are disseminated globally. Their productivity is impacted by infectious diseases thus impacting the livestock owners and the community. γδ T lymphocytes or T cells have vital roles in immune responses in mammals and thus we identified information gaps regarding these cells in goats. We used genome annotation, PCR amplification of genomic DNA and cDNA, and Sanger and PacBio sequencing for this research to …


Dynamic Evolution In The Leucine-Rich Repeat Receptor-Like Kinase (Lrr-Rlk) Family Of Receptors, Jarrett Man Apr 2021

Dynamic Evolution In The Leucine-Rich Repeat Receptor-Like Kinase (Lrr-Rlk) Family Of Receptors, Jarrett Man

Doctoral Dissertations

Cells in multicellular organisms must gauge their environmental conditions, including neighboring cells, during development. In plants, the Leucine-Rich Repeat Receptor-like Kinases (LRR-RLKs) encode a family of membrane-bound receptors that transduce such cell-to-cell signals and are required for many aspects of plant development. Very little is known about the function of most of these genes, and the evolutionary history of the family is difficult to infer because of its size and complexity. Several factors contribute to this difficulty, including genetic redundancy, challenging bioinformatic detection, exceptionally large family size, and high copy number variation among species. In this dissertation, I characterize some …


Physiological Constraints, Mechanisms, And Mineral Transformations Of Iron Reduction In Hyperthermophilic Crenarchaea, Srishti Kashyap Apr 2021

Physiological Constraints, Mechanisms, And Mineral Transformations Of Iron Reduction In Hyperthermophilic Crenarchaea, Srishti Kashyap

Doctoral Dissertations

Dissimilatory iron reduction by hyperthermophilic archaea occurs in many geothermal environments and typically relies on microbe-mineral interactions that transform various iron oxide minerals. However, the kinds of iron oxides that can be used, growth rates, extent of iron reduction, and the mineral transformations that occur due to this metabolism are poorly understood. This dissertation improves our fundamental understanding of the physiological mechanisms and mineral transformations of hyperthermophilic iron reduction using two model crenarchaea, Pyrodictium delaneyi and Pyrobaculum islandicum. Using growth yields and metabolite production rates, we demonstrated that a broad range of Fe(III) (oxyhydr)oxides of variable thermodynamic stability was …