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Drivers And Consequences Of Carbon Use Efficiency - And Its Measurement In Soil, Grace Pold Oct 2019

Drivers And Consequences Of Carbon Use Efficiency - And Its Measurement In Soil, Grace Pold

Doctoral Dissertations

Soils serve as massive carbon sinks, but their ability to continue this ecological service is contingent on how the resident soil microbial community will respond to the ongoing climate crisis. One key dimension of the microbial response to warming is its carbon use efficiency (CUE), or the fraction of carbon taken up by an organism which is allocated to growth rather than respiration. However, the scientific community is still in the early stages of understanding the drivers, consequences - and even accurate measurements of - CUE. In this dissertation, I first quantified the variability of CUE and its responsiveness to temperature and ...


The Spatial Organization Of Mycobacterial Membrane, Julia Puffal Jul 2019

The Spatial Organization Of Mycobacterial Membrane, Julia Puffal

Doctoral Dissertations

Mycobacteria comprises a large group of organisms including the pathogenic species Mycobacterium tuberculosis, the causative agent of tuberculosis. A fast- growing saprophytic member of this genus, however, Mycobacterium smegmatis, is oftentimes used as a model organism for the pathogenic species. With a unique cell envelope architecture and unconventional polar growth, spatial coordination of cell envelope biosynthesis is vital for proper assembly of this complex structure. Here, we provide a comprehensive overview of known lateral heterogeneities in mycobacterial plasma membrane, with a particular focus on the intracellular membrane domain (IMD), a spatially distinct region of the plasma membrane with diverse functions ...


Studies On The Interaction And Organization Of Bacterial Proteins On Membranes, Mariana Brena Jul 2019

Studies On The Interaction And Organization Of Bacterial Proteins On Membranes, Mariana Brena

Masters Theses

Bacteria have developed various means of secreting proteins that can enter the host cell membrane. In this work I focus on two systems: cholesterol-dependent cytolysins and Type III Secretion.

Cholesterol is a molecule that is critical for physiological processes and cell membrane function. Not only can improper regulation lead to disease, but also the role cholesterol plays in cell function indicates it is an important molecule to understand. In response to this need, probes have been developed that detect cholesterol molecules in membranes. However, it has been recently shown that there is a need for probes that only respond to ...


Hybridized Polymeric Nano-Assemblies: Key Insights Into Addressing Mdr Infections, Ryan Landis Mar 2019

Hybridized Polymeric Nano-Assemblies: Key Insights Into Addressing Mdr Infections, Ryan Landis

Doctoral Dissertations

Multidrug-resistant (MDR) bacteria contribute to more than 700,000 annual deaths world-wide. Millions more suffer from limb amputations or face high healthcare treatment costs where prolonged and costly therapeutic regimens are used to counter MDR infections. While there is an international push to develop novel and more powerful antimicrobials to address the impending threat, one particularly interesting approach that has re-emerged are essential oils, phytochemical extracts derived from plant sources. While their antimicrobial activity demonstrates a promising avenue, their stability in aqueous media, limits their practical use in or on mammals. Inspired by the versatility of polymer nanotechnology and the ...


Nascent Dna Proteomics Analysis Uncovers Dna Replication Dynamics In The Human Pathogen Trypanosoma Brucei, Maria Rocha Granados Mar 2019

Nascent Dna Proteomics Analysis Uncovers Dna Replication Dynamics In The Human Pathogen Trypanosoma Brucei, Maria Rocha Granados

Doctoral Dissertations

DNA is the substrate of many cellular processes including DNA replication, transcription and chromatin remodeling. These processes are coordinated to maintain genome integrity and ensure accurate duplication of genetic and epigenetic information. Genome-wide studies have provided evidence of the relationship between transcription and DNA replication timing. A global analysis of DNA replication initiation in T. brucei showed that TbORC1 (subunit of the origin recognition complex, ORC) binding sites are located at the boundaries of transcription units. Although recent studies in T. brucei indicate functional links among DNA replication and transcription, the underlying mechanisms remain unknown. In this study, we adapted ...


Protein Degradation Regulates Phospholipid Biosynthetic Gene Expression In Saccharomyces Cerevisiae, Bryan Salas-Santiago Mar 2019

Protein Degradation Regulates Phospholipid Biosynthetic Gene Expression In Saccharomyces Cerevisiae, Bryan Salas-Santiago

Doctoral Dissertations

Transcriptional regulation of most phospholipid biosynthetic genes in Saccharomyces cerevisiae is coordinated by inositol and choline. Inositol affects phosphatidic acid (PA) intracellular levels. Opi1p interacts physically with PA and is the main repressor of the phospholipid biosynthetic genes. It is localized in the endoplasmic reticulum (ER) bound to the ER membrane protein Scs2p. When PA levels drop, Opi1p is translocated into the nucleus repressing most phospholipid biosynthetic genes. The OPI1 locus was identified in a screen looking for overproduction and excretion of inositol (Opi-). Opi- mutants are generally associated with a defect in repression of the ...


Dissecting Regulatory Mechanisms Of Coma-Dependent And Coma-Independent Quorum Sensing Pathways In Bacillus Subtilis, Emily Roy Oct 2018

Dissecting Regulatory Mechanisms Of Coma-Dependent And Coma-Independent Quorum Sensing Pathways In Bacillus Subtilis, Emily Roy

Doctoral Dissertations

Virtually all living organisms are capable of sensing individuals within a population and communicating amongst themselves to coordinate group behavior. This group coordination holds true for all living organisms, from multi-cellular organisms like humans down to the single-celled microbes including bacteria. In order to survive in everchanging environments, bacteria have developed strategies to determine their current surroundings and communicate with individuals in the population to respond to environmental changes. Bacteria have many different forms of communication similar to the many different human languages. These signals are used to coordinate a variety of biological processes in a density-dependent manner in a ...


Clpxp-Regulated Proteins Suppress Requirement For Reca In Dam Mutants Of Escherichia Coli K-12, Amie Savakis Oct 2018

Clpxp-Regulated Proteins Suppress Requirement For Reca In Dam Mutants Of Escherichia Coli K-12, Amie Savakis

Masters Theses

Double strand breaks (DSB) are a common source of DNA damage in both prokaryotes and eukaryotes. If they are not repaired or are repaired incorrectly, they can lead to cell death (bacteria) or cancer (humans). In Escherichia coli, repair of DSB are typically accomplished via homologous recombination and mediated by RecA. This repair pathway, among others, is associated with activation of the SOS response. DNA adenine methyltransferase (dam) mutants have an increased number of DSB and, therefore, are notorious for being RecA-dependent for viability. Here, we show that the synthetic lethality of Δdam/ΔrecA is suppressed when clpP is removed ...


Hydrogen Stress And Syntrophy Of Hyperthermophilic Heterotrophs And Methanogens, Begum Topcuoglu Jul 2018

Hydrogen Stress And Syntrophy Of Hyperthermophilic Heterotrophs And Methanogens, Begum Topcuoglu

Doctoral Dissertations

Approximately 1 giga ton (Gt, 1015 g) of CH4 is formed globally per year from H2, CO2, and acetate through methanogenesis, largely by methanogens growing in syntrophic association with anaerobic microbes that hydrolyze and ferment biopolymers. However, our understanding of methanogenesis in hydrothermal regions of the subseafloor and potential syntrophic methanogenesis at thermophilic temperatures is nascent. This dissertation shows that thermophilic H2 syntrophy can support methanogenesis within natural microbial assemblages at hydrothermal vents and that it can be an important alternative energy source for thermophilic autotrophs in marine geothermal environments. This dissertation also elucidates H ...


Impacts Of Genome And Nuclear Architecture On Molecular Evolution In Eukaryotes, Xyrus Maurer-Alcalá Mar 2018

Impacts Of Genome And Nuclear Architecture On Molecular Evolution In Eukaryotes, Xyrus Maurer-Alcalá

Doctoral Dissertations

The traditional view of genomes suggests that they are static entities changing slowly in sequence and structure through time (e.g. evolving over geological time-scales). This outdated view has been challenged as our understanding of the dynamic nature of genomes has increased. Changes in DNA content (i.e. polyploidy) are common to specific life-cycle stages in a variety of eukaryotes, as are changes in genome content itself. These dramatic genomic changes include chromosomal deletions (i.e. paternal chromosome deletion in insects; Goday and Esteban 2001; Ross, et al. 2010), developmentally regulated genome rearrangements (e.g. the V(D)J system ...


Structure-Property Relationships Of Polymer Films And Hydrogels To Control Bacterial Adhesion, Kristopher W. Kolewe Mar 2018

Structure-Property Relationships Of Polymer Films And Hydrogels To Control Bacterial Adhesion, Kristopher W. Kolewe

Doctoral Dissertations

The emergence and spread of antibiotic resistance across microbial species necessitates the need for alternative approaches to mitigate the risk of infection without relying on commercial antibiotics. Biofilm-related infections are a class of notoriously difficult to treat healthcare-associated infections that frequently develop on the surface of implanted medical devices. As biofilm formation is a surface-associated phenomenon, understanding how the intrinsic properties of materials affect bacterial adhesion enables the development of structure-property relationships that can guide the future design of infection-resistant materials. Despite lacking visual, auditory, and olfactory perception, bacteria still manage to sense and attach to surfaces. Previously, it has ...


The Role Of The Metallochaperone Hypa In The Acid Survival And Activities Of Nickel Enzymes In Helicobacter Pylori, Heidi Hu Mar 2018

The Role Of The Metallochaperone Hypa In The Acid Survival And Activities Of Nickel Enzymes In Helicobacter Pylori, Heidi Hu

Doctoral Dissertations

Helicobacter pylori is a bacterium that has colonized the human gastric mucosa of over 50% of the world population. Persistent infection can cause gastritis, peptic ulcers, and cancers. The ability of H. pylori to colonize the acidic environment of the human stomach is dependent on the activity of the nickel containing enzymes, urease and NiFe-hydrogenase. The nickel metallochaperone, HypA, was previously shown to be required for the full activity of both enzymes. In addition to a Ni-binding site, HypA also contains a structural Zn site, which has been characterized to alter its averaged structure depending on pH and the presence ...


Microbial Competition In Bioelectrochemical Systems, Varun Srinivasan Nov 2017

Microbial Competition In Bioelectrochemical Systems, Varun Srinivasan

Doctoral Dissertations

Bioelectrochemical systems(BESs)/ microbial fuel fells (MFCs) are a well-studied potential technology for bioremediation and decentralized wastewater treatment. However, progress has been somewhat stalled at the bench-scale. In well controlled experiments electron recovery is high. In natural environments, wastewaters are complex and anode-respiring bacteria can be outcompeted in the presence of competing microorganisms, leading to a loss in electron-recovery and power production. Furthermore, the cathode of the MFC plays a vital role in providing flexibility for treatment options but is an understudied part of MFCs.

Modelling Intracellular Competition in a Denitrifying Biocathode:

One potential MFC configuration uses an organic-oxidizing anode ...


Regulated Proteolysis Of Dnaa Coordinates Cell Growth With Stress Signals In Caulobacter Crescentus, Jing Liu Nov 2017

Regulated Proteolysis Of Dnaa Coordinates Cell Growth With Stress Signals In Caulobacter Crescentus, Jing Liu

Doctoral Dissertations

DNA replication is an essential process in all domains of life. Replication must be precisely regulated, especially at the step of initiation. In bacteria, the replication initiator DnaA is regulated by multiple post-translational regulations to ensure timely replication. Caulobacter crescentus has the most strict replication regulation that DNA only replicates once per cell cycle, and proteolysis of DnaA identified in this species is the only irreversible way to inhibit DnaA, suggesting it might be pivotal to restricting DNA replication. However, the responsible protease(s) and mechanism for its degradation remain unclear since its first discovery in 2005. In this thesis ...


Microbial Dynamics And Design Considerations For Decentralized Microbial Fuel Cell Applications, Cynthia Castro Nov 2017

Microbial Dynamics And Design Considerations For Decentralized Microbial Fuel Cell Applications, Cynthia Castro

Doctoral Dissertations

The purpose of this dissertation was to assess the practicality of using microbial fuel cells (MFCs) as alternative sanitation systems for wastewater treatment and energy recovery, focusing on identifying key design considerations for treating high strength wastewater and managing alternative metabolic pathways.

We evaluated the energetic outputs of a lab-based pilot MFC designed to treat complex organics present in both synthetic feces and municipal wastewater. The pilot MFC produced two energetic products, methane and electricity, when treating two types of complex wastewaters. The energetic products associated with anode respiration and methanogenesis were simultaneously observed and yielded a combined energy ouput ...


Investigating Natural And Induced Biofilm Dispersion In Listeria Monocytogenes, Brett Boulden Oct 2017

Investigating Natural And Induced Biofilm Dispersion In Listeria Monocytogenes, Brett Boulden

Masters Theses

Dispersion is a natural part of a biofilm life cycle in many bacterial species. Dispersion occurs when bacteria revert from a stationary, sessile state to a free-swimming, planktonic state and are freed from a biofilm. Bacterial biofilms consist of proteins, polysaccharides, and extracellular DNA that together make up the extracellular polymeric substances. Surrounded by this mucus-like substance, sessile cells can be extremely difficult to eradicate as compared to the planktonic form of Listeria monocytogenes. Biofilms are robust due to increased surface adherence, inhibition of diffusion of harmful compounds, and increased genetic diversity that exists within a biofilm. As a result ...


The Effects Of Anthropogenic Stress On Nitrogen-Cycling Microbial Communities In Temperate And Tropical Soils, George S. Hamaoui Jr. Jul 2017

The Effects Of Anthropogenic Stress On Nitrogen-Cycling Microbial Communities In Temperate And Tropical Soils, George S. Hamaoui Jr.

Doctoral Dissertations

In this dissertation several research studies are discussed that characterize the effects of anthropogenic, or human-induced, stress on both ammonia-oxidizing and total bacterial soil microbial communities. The disturbances of land-use change in tropical, South American rainforests and artificial warming and nitrogen (N) fertilization in temperate, North American forests were investigated as these disturbances represent past and current disturbances caused by human landscape alteration and climate change. Initially, the response of soil ammonia-oxidizing microbial communities to land-use change from primary rainforest to pasture and, finally, back to secondary forest was determined. Next, these analyses of land-use change effects were expanded to ...


The Key Question In Symbiotic Nitrogen Fixation: How Does Host Maintain A Bacterial Symbiont?, Onur Oztas Jul 2017

The Key Question In Symbiotic Nitrogen Fixation: How Does Host Maintain A Bacterial Symbiont?, Onur Oztas

Doctoral Dissertations

The fact that plants cannot use nitrogen in the gaseous form makes them dependent on the levels of usable nitrogen forms in the soil. Legumes overcome nitrogen limitation by entering a symbiotic association with rhizobia, soil bacteria that convert atmospheric nitrogen into usable ammonia. In root nodules, bacteria are internalized by host plant cells inside an intracellular compartment called the symbiosome where they morphologically differentiate into nitrogen-fixing forms by symbiosome-secreted host proteins.

In this project, I explained the host proteins required to maintain bacterial symbionts and described their delivery to the symbiosome. I showed that the SYNTAXIN 132 (SYP132) gene ...


A Novel Periplasmic Protein Involved In The Mannan Chain Elongation Step Of Lipomannan And Lipoarabinomannan Biosynthesis In Mycobacterium Smegmatis, Stephanie A. Ha Mar 2017

A Novel Periplasmic Protein Involved In The Mannan Chain Elongation Step Of Lipomannan And Lipoarabinomannan Biosynthesis In Mycobacterium Smegmatis, Stephanie A. Ha

Masters Theses

Mycobacteria are atypical bacteria possessing unusual cell envelopes comprised of an outer membrane, covalently linked to an arabinogalacatan-peptidoglycan structure via waxy mycolic acids, in addition to the conventional inner membrane. This thick and highly impermeable cell envelope is a major deterrent to antibiotic treatment of clinically relevant mycobacterial pathogens, including Mycobacterium tuberculosis (Mtb), which infects a third of the world’s population and kills millions each year. Thus, the regulation of mycobacterial cell envelope biosynthesis is of great interest for the development of more effective therapeutics for treating Mtb infections. Using the model organism Mycobacterium smegmatis (M. smegmatis), we identified ...


Intracellular Membrane Organization In Mycobacteria, Jennifer Hayashi Mar 2017

Intracellular Membrane Organization In Mycobacteria, Jennifer Hayashi

Doctoral Dissertations

Mycobacterium is a diverse genus of actinobacteria that includes the causative agents of human tuberculosis and leprosy. Mycobacteria are protected by their unique, multilaminar cell envelope, which grants them intrinsic resistance to environmental challenges such as antibiotics. This essential cellular structure is elongated at the polar ends of cells, but the regulation of cytosolic precursor synthesis and localized envelope synthesis remains unclear. Here, we present the PMf (plasma membrane free of cell wall components), a membrane domain distinct from the bulk plasma membrane of Mycobacterium smegmatis. Proteomic and lipidomic characterization demonstrate that the PMf contains lipidic substrates of cell envelope ...


Expansion Of And Reclassification Within The Family Lachnospiraceae, Kelly N. Haas Nov 2016

Expansion Of And Reclassification Within The Family Lachnospiraceae, Kelly N. Haas

Doctoral Dissertations

Many of the taxa in the family Lachnospiraceae are currently misclassified as Clostridium spp. Here attempt to rectify many of these issues, beginning with an in-depth genomic and physiologic analysis of Clostridium methoxybenzovorans, culminating in the assertion that is a heterotype of Clostridium indolis, followed by reclassification of the broader group in which this organism resides. We propose two novel genera, Lacriformis and Enterocloster, to reclassify this clade, this includes reclassification of Clostridium sphenoides, Clostridium indolis, Clostridium saccharolyticum, Clostridium celerecrescens, Clostridium xylanolyticum, Clostridium algidixylanolyticum, Clostridium aerotolerans, Clostridium amygdalinum, and Desulfotomaculum guttoideum as Lacriformis sphenoides, comb. nov., Lacriformis indolis, comb. nov ...


Biopolymer Electrospun Nanofiber Mats To Inactivate And Remove Bacteria, Katrina Ann Rieger Nov 2016

Biopolymer Electrospun Nanofiber Mats To Inactivate And Remove Bacteria, Katrina Ann Rieger

Doctoral Dissertations

The persistence of antibiotic resistance in bacterial pathogens remains a primary concern for immunocompromised and critically-ill hospital patients. Hospital associated infections can be deadly and reduce the successes of medical advancements, such as, cancer therapies and medical implants. Thus, it is imperative to develop materials that can (i) deliver new antibiotics with accuracy, as well as (ii) uptake pathogenic microbes. In this work, we will demonstrate that electrospun nanofiber mats offer a promising platform for both of these objectives because of their high surface-to-volume ratio, interconnected high porosity, gas permeability, and ability to contour to virtually any surface. To provide ...


Trypanosoma Brucei Mitochondrial Dna Polib Cell Cycle Localization And Effect On Polic When Polib Is Depleted, Sylvia L. Rivera Nov 2016

Trypanosoma Brucei Mitochondrial Dna Polib Cell Cycle Localization And Effect On Polic When Polib Is Depleted, Sylvia L. Rivera

Masters Theses

Trypanosoma brucei is the causative agent of Human African Trypanosomiasis (HAT), also known as African sleeping sickness. T. brucei is unique in several ways that distinguish this organism from other eukaryotes. One of the unique features of T. brucei is the organism’s mitochondrial DNA, which is organized in a complex structure called kinetoplast DNA (kDNA). Since kDNA is unique to the kinetoplastids, kDNA may serve as a good drug target against T. brucei. Previews studies have shown that kDNA has 4 different family A mitochondrial DNA polymerases. Three of these mitochondrial DNA polymerases (POLIB, POLIC, and POLID) are essential ...


Distribution Of Enterotoxigenic Clostridium Perfringens Spores In U.S. Retail Spices, Chi-An Lee Nov 2016

Distribution Of Enterotoxigenic Clostridium Perfringens Spores In U.S. Retail Spices, Chi-An Lee

Masters Theses

246 samples of bulk and packaged spices from retail stores in the western, southeastern, southern, midwestern, and northeastern areas of the U.S. were examined for the presence of Clostridium -perfringens. Isolates were checked for the presence of the lecithinase gene (cpa) and enterotoxin genes (cpe) by PCR. Enterotoxin formation during sporulation was investigated using the Oxoid Toxin Detection Kit. Forty-three confirmed isolates (from 17% of total samples) were cpa-positive. Of those, 27 were cpe-positive. Together, levels of C. perfringens spores ranged from 3.6-2400/gm. The amount of enterotoxin in cell extracts ranged from 2-16 ng/ml ...


Novel Advancements For Improving Sprout Safety, Kyle S. Landry Jul 2016

Novel Advancements For Improving Sprout Safety, Kyle S. Landry

Doctoral Dissertations

All varieties of bean sprouts (mung bean, alfalfa, broccoli, and radish) are classified as a “super-food” and are common staples for health conscious consumers. Along with the proposed health benefits, there is also an inherent risk of foodborne illness. When sprouts are cooked, there is little risk of illness. The purpose of this dissertation was to explore novel techniques to minimize or prevent the incidence of foodborne illness associated with the consumption of sprouts. Three areas were investigated: 1) the use of a biocontrol organism, 2) the use of a novel spontaneous carvacrol nanoemulsion, and 3) the influence of the ...


Conversion Of Cellulose To Ethanol By The Biofuels Microbe Clostridium Phytofermentans: Quantification Of Growth And Role Of An Rnf-Complex In Energy Conservation, Jesús G. Alvelo-Maurosa Jul 2016

Conversion Of Cellulose To Ethanol By The Biofuels Microbe Clostridium Phytofermentans: Quantification Of Growth And Role Of An Rnf-Complex In Energy Conservation, Jesús G. Alvelo-Maurosa

Doctoral Dissertations

The anaerobic mesophilic bacterium Clostridium phytofermentans grows and ferments multiple plant-based substrates into ethanol as the main product of fermentation. The capacity of C. phytofermentans to convert plant biomass into ethanol, propanol, and short-chain fatty acids is strongly attractive for industry. Specific physiological capabilities of C. phytofermentans allow the microbe to generate high amounts of ethanol compared to acetate. However, little is known about membrane energetics in C. phytofermentans, or its role in energy conservation and production of high levels of ethanol during fermentation of plant biomass substrates.

In the first research project presented in this dissertation, we examined C ...


Promoting Extracellular Matrix Crosslinking In Synthetic Hydrogels, Marcos M. Manganare Nov 2015

Promoting Extracellular Matrix Crosslinking In Synthetic Hydrogels, Marcos M. Manganare

Masters Theses

The extracellular matrix (ECM) provides mechanical and biochemical support to tissues and cells. It is crucial for cell attachment, differentiation, and migration, as well as for ailment-associated processes such as angiogenesis, metastases and cancer development. An approach to study these phenomena is through emulation of the ECM by synthetic gels constructed of natural polymers, such as collagen and fibronectin, or simple but tunable materials such as poly(ethylene glycol) (PEG) crosslinked with short peptide sequences susceptible to digestion by metalloproteases and cell-binding domains. Our lab uses PEG gels to study cell behavior in three dimensions (3D). Although this system fosters ...


Energetic Limitations Of Thermophilic Methanogens And Thiosulfate Reducers In The Subsurface Biosphere At Deep-Sea Hydrothermal Vents, Lucy C. Stewart Nov 2015

Energetic Limitations Of Thermophilic Methanogens And Thiosulfate Reducers In The Subsurface Biosphere At Deep-Sea Hydrothermal Vents, Lucy C. Stewart

Doctoral Dissertations

This dissertation examined the substrate and energetic limitations of hydrogenotrophic thermophiles from deep-sea hydrothermal vents. Thermophilic and hyperthermophilic organisms in diffuse hydrothermal venting are thought to represent a hot subsurface biosphere associated with deep-sea hydrothermal vents, where primary production is dominated by hydrogenotrophy rather than sulfide oxidation as at the vent/seawater interface of hydrothermal sulfide chimneys. Methanogens and sulfur-reducers are known to compete for hydrogen in mesophilic, freshwater systems, and likely do so in deep-sea hydrothermal vent environments as well. However, the exact size and biomass of the subsurface biosphere is difficult to determine through direct sampling.

Firstly, the ...


Engineering Novel Detection And Treatment Strategies For Bacterial Therapy Of Cancer, Jan T. Panteli Aug 2015

Engineering Novel Detection And Treatment Strategies For Bacterial Therapy Of Cancer, Jan T. Panteli

Doctoral Dissertations

Finding and treating cancer is difficult due to limited sensitivity and specificity of current detection and treatment strategies. Many chemotherapeutic drugs are small molecules that are limited by diffusion, making it difficult to reach cancer sites requiring high doses that lead to systemic toxicity and off-target effects. Tomographic detection techniques, like PET, MRI and CT, are good at identifying macroscopic lesions in the body but are limited in their ability to detect microscopic lesions. Biomarker detection strategies are extremely sensitive and able to identify ng/ml concentrations of protein, but are poor at discriminating between healthy and disease state levels ...


Dissolution, Ocean Acidification And Biotic Extinctions Prior To The Cretaceous/Paleogene (K/Pg) Boundary In The Tropical Pacific, Serena Dameron Jul 2015

Dissolution, Ocean Acidification And Biotic Extinctions Prior To The Cretaceous/Paleogene (K/Pg) Boundary In The Tropical Pacific, Serena Dameron

Masters Theses

The several million years preceding the Cretaceous/Paleogene (K/Pg) boundary has been the focus of many studies. Changes in ocean circulation and sea level, extinctions, and major volcanic events have all been documented for this interval. Important research questions these changes raise include the climate dynamics during the warm, but not hot, time after the decay of the Late Cretaceous greenhouse interval and the stability of ecosystems prior to the mass extinctions at the end-Cretaceous.

I document several biotic perturbations as well as changes in ocean circulation during the Maastrichtian stage of the latest Cretaceous that question whether the ...