Biology Commons^™

Nitrogen Fixation By The Cyanobacterium Nostoc Punctiforme In Response To Variation In Nitrogen Availability, Temperature, And Atmospheric Co2 Concentrations, Danielle A. Griffith

Electronic Thesis and Dissertation Repository

The predominant input of available nitrogen (N) in boreal forest ecosystems originates from moss-associated cyanobacteria, which fix unavailable atmospheric N₂, contribute to the soil N pool, and thereby support forest productivity. Although increases in N availability, temperature, and atmospheric CO₂ concentrations are expected in Canada’s boreal region over the next century, little is known about the combined effects of these factors on N₂ fixation by axenic cyanobacteria or the associated mechanisms. I assessed changes in N₂ fixation by Nostoc punctiforme under different global environmental change scenarios and examined correlations between the response and changes in …

Differential Expression Of Snmps And Their Underlying Transcriptional Regulation In Chemosensory Pathways Of Drosophila, Richard A. Fandino

Theses and Dissertations

Insects possess complex and diverse chemosensory pathways which have specific phenotypes determined by the regulated expression of specific combinations of genes. While many of these genes (e.g. ORs and GRs) have very narrow expression patterns, associating with only a limited number of chemosensory sensilla, SNMPs show a very broad expression pattern. In Drosophila, SNMP1 and SNMP2 associate with the majority of olfactory and gustatory sensilla, but express in different cell types. In olfactory sensilla, SNMP1 and SNMP2 associate with trichoid or coeloconic neurons respectively, and both additionally express in a variety of sensilla support cells; in gustatory sensilla, SNMP2 expresses …

Utilizing Next Generation Sequencing To Generate Bacterial Genomic Sequences For Evolutionary Analysis, Derrick C. Scott

Theses and Dissertations

Many important questions in the field of prokaryotic biology cannot be answered due to the low availability of sequenced and finished genomes. Recent improvements in technology and decreases in price have made the ambition of de novo bacterial genomic sequencing a reality for a wide range of researchers. However, with the advancement of sequencing technology comes the need for an evaluation to determine the most reliable bioinformatics methods in generating a complete and accurate assembly. Biases inherent in the sequencing technology and GC-rich genomes complicate genome assemblies. Here, we sequenced bacterial strains from the GC-rich Caulobacter genus and the closely …

Role Of Apelin And Endothelin Systems In The Pain Associated With Sickle Cell Disease, Terika Smith

Theses and Dissertations

Sickle cell disease (SCD) is a common genetic blood disorders that is characterized by painful vaso-occlusive episodes (VOEs), which are the major cause of hospitalizations for these patients. One of the mechanisms that may contribute to the development of painful VOEs is the imbalance between vasoconstrictors and vasodilators. This thesis focuses on the vasoconstrictors endothelin-1 (ET-1), which is elevated during VOEs and is pro-nociceptive, and angiotensin II (Ang II) and the vasodilator apelin, which has anti-nociceptive properties. This thesis tested two hypotheses: 1) an imbalance between the vasoconstrictive and pro-nociceptive systems and vasodilatory and anti-nociceptive systems contributes to pain in …

Muscarinic Modulation Of Basolateral Amygdala, Lei Liu

Theses and Dissertations

The basolateral amygdala (BL) receives a dense cholinergic innervation from the basal forebrain. Despite the importance of muscarinic acetylcholine receptors (mAChRs) in fear learning, consolidation, and extinction, there have been no studies that have systematically investigated the functional role of mAChRs in regulating emotional processing in the BL. To address this critical knowledge gap we combined brain slice whole-cell recording, optogenetics, and immunohistochemistry to determine how muscarine, acting on mAChRs, regulates neuronal oscillations, synaptic transmission and plasticity in the BL.

Neurons in the BL oscillate rhythmically during emotional processing, which are thought to be important to integrate sensory inputs, allow …

Mechanical Properties Of Diet And Its Effect On Oral Health, Varsha Kapoor

Theses and Dissertations

The predominant diet fed to captive carnivores consists of ground meat formulated to provide full nutritional requirements. However, this ground meat diet completely lacks the mechanical properties such as toughness, hardness and stiffness of the foods the animals would eat in the wild. The goal of this research was to evaluate the effect of mechanical properties of diet on oral health by comparing prevalence of periodontal disease and calculus accumulation in wild and captive felids. One-way ANOVA analysis of variance indicated that these differences are statistically significant (P

Functional Characterization Of Fro4 And Fro5: Two Members Of The Ferric Chelate Reductase Family Of Arabidopsis, Grandon Thomas Wilson

Theses and Dissertations

Iron (Fe) is the fourth most abundant element within the earth’s crust and is an essential micronutrient for plants and animals. Fe plays key roles in photosynthesis, respiration and chlorophyll biosynthesis in plants and in hemoglobin in animals. Like Fe, copper (Cu) is also an important micronutrient in plants and is needed for photosynthesis and respiration, especially in the important copper-containing protein plastocyanin. Copper also is important in scavenging reactive oxygen species and ethylene perception. The reduction of Fe3+ to Fe2+ at the root surface of Arabidopsis thaliana during times of Fe deficiency has been a well-characterized process; however, reduction …

Genetic Background Influences Behavior And Responses To Epigenetic Changes Induced By A Methyl-Donor Diet, Kimberly R. Shorter

Theses and Dissertations

With recent strides in epigenetics, mainstream media informs the public that we can “beat our genes” by, for instance, changing our diet. Genetics, however, still plays a role in phenotype. Folate and other methyl-donor pathway components are widely supplemented due to their ability to prevent neural tube defects during prenatal development. In addition to vitamins, these compounds are also added to commercial flour, energy drinks, and other supplements. Several lines of evidence suggest that these supplements act through epigenetic mechanisms, including altering DNA methylation. Increasing evidence suggests potential deleterious effects of excessive folate. Given the benefits of these compounds, risk …

An Investigation Of Mitochondrial Bioenergetics And The Turnover Of Succinated Proteins In The Adipocyte During Diabetes, Ross Tanis

Theses and Dissertations

We previously identified the chemical modification S-(2-succino)cysteine (2SC), which is formed when the Krebs cycle metabolite fumarate reacts with protein cysteine residues, also termed protein succination. Protein succination is increased in the adipose tissue of ob/ob and db/db mice in vivo and in 3T3-L1 adipocytes grown in high glucose in vitro. The increase in 2SC in the 3T3-L1 adipocyte occurs as a direct result of glucotoxicity and increased mitochondrial stress. We have shown that uncoupling agents, which lower mitochondrial stress, prevent the increase in succinated proteins.

In this study we examined the relationship between increased succination and mitochondrial bioenergetics in …

Enhancement Of Chronically Induced Breast Carcinogenesis By Combined Environmental And Dietary Carcinogens And Suppression By Dietary Agents, Lenora A. Pluchino Ph.D.

Lenora A. Pluchino, Ph.D.

Most breast cancers occur sporadically due to long-term exposure to low-dose carcinogens present in our environment and diet. American lifestyles involve frequent exposures to smoke, polluted air, and high temperature-cooked meats comprising multiple carcinogens, such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), benzo[α[alpha]]pyrene (B[α[alpha]]P), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). To investigate whether these carcinogens may act together to enhance breast cell carcinogenesis, we used our chronically-induced breast cell carcinogenesis model wherein we repeatedly expose non-cancerous human breast epithelial MCF10A cells to physiologically-achievable doses of carcinogens to progressively induce cellular acquisition of cancer-associated properties including reduced dependence on growth factors, anchorage-independent growth, increased cell proliferation, migration and …

Phenotypic Signatures Arising From Unbalanced Bacterial Growth, Cheemang Tan, Robert P. Smith, Ming-Chi Tsai, Russell Schwartz, Lingchong You

Biology Faculty Articles

Fluctuations in the growth rate of a bacterial culture during unbalanced growth are generally considered undesirable in quantitative studies of bacterial physiology. Under well-controlled experimental conditions, however, these fluctuations are not random but instead reflect the interplay between intra-cellular networks underlying bacterial growth and the growth environment. Therefore, these fluctuations could be considered quantitative phenotypes of the bacteria under a specific growth condition. Here, we present a method to identify “phenotypic signatures” by time-frequency analysis of unbalanced growth curves measured with high temporal resolution. The signatures are then applied to differentiate amongst different bacterial strains or the same strain under …

Determining The Binding Between Saga Subunits And Spliceosomal Components, Peyton J. Spreacker, Rachel L. Stegeman, Vikki M. Weake

The Summer Undergraduate Research Fellowship (SURF) Symposium

Proper gene regulation is vital to the health and development of an organism. Determining the relationship between splicing, transcription, and chromatin structure is vital for understanding gene regulation as a whole. There have been previous studies linking these elements pairwise; however, no evidence exists for a direct link between all three. Recent data shows that splicing components of the U2 small nuclear ribonucleic protein (snRNP) co-purify with Spt-Ada-Gcn5-acetyltransferase (SAGA), a highly conserved transcriptional co-activator and chromatin modifier. We hypothesize that SAGA binds with splicing components through a multi-protein binding surface with certain core components based on preliminary yeast two-hybrid data. …

Interaction Between Insecticide Exposure And Trematode Infection Across Four Wood Frog Populations, Michael J. Hiatt, Jessica Hua Dr., Vanessa Wuerthner, Jason Hoverman Dr.

The Summer Undergraduate Research Fellowship (SURF) Symposium

Amphibian populations are declining worldwide due to a number of stressors including pesticides and parasites. Conservation of these animals can be complicated because populations can differ dramatically in response to the same stressor. When consistently exposed to pesticides, some populations evolve tolerance through the process of natural selection acting across multiple generations. Alternatively, populations that are intermittently exposed to pesticides induce tolerance within a single generation. To date, however, there have been few studies examining the costs associated with these different stress tolerance mechanisms. In this study, we examined how difference in stress tolerance influence susceptibility to parasitic infections. We …

Electrophoresis Staining: A New Method Of Whole Mount Staining, Mitchell G. Ayers, Sarah Calve, Zhiyu Li

The Summer Undergraduate Research Fellowship (SURF) Symposium

Advances in tissue clearing techniques have allowed almost a ten-fold increase in the viewing depth of confocal microscopy. This allows for intact cellular structures to be rendered in 3D. However, viewing tissues to this depth is often limited to endogenous fluorescence as passive diffusion of antibodies via whole mount staining can take weeks. Our lab is developing a new method involving electrophoresis as a driving force that will promote active antibody binding deep into tissue, reducing the amount of time needed to stain for cellular structures. Due to the inherent charge within antibodies, they are able to be directionally forced …

The Geomagnetic Environment In Which Sea Turtle Eggs Incubate Affects Subsequent Magnetic Navigation Behaviour Of Hatchlings, Matthew J. Fuxjager, Kyla R. Davidoff, Lisa A. Mangiamele, Kenneth J. Lohmann

Biological Sciences: Faculty Publications

Loggerhead sea turtle hatchlings (Caretta caretta) use regional magnetic fields as open-ocean navigational markers during trans-oceanic migrations. Little is known, however, about the ontogeny of this behaviour. As a first step towards investigating whether the magnetic environment in which hatchlings develop affects subsequent magnetic orientation behaviour, eggs deposited by nesting female loggerheads were permitted to develop in situ either in the natural ambient magnetic field or in a magnetic field distorted by magnets placed around the nest. In orientation experiments, hatchlings that developed in the normal ambient field oriented approximately south when exposed to a field that exists near the …

The Role Of Lactate Dehydrogenase B In Aerobic Glycolysis-Mediated Resistance To Ab Toxicity, Tyler Tam

Electronic Thesis and Dissertation Repository

Alzheimer’s disease is a progressive, neurodegenerative disorder characterized by the accumulation of amyloid β (Aβ) plaques in affected brain regions. Strong evidence indicates that Aβ exerts neurotoxic effects by promoting mitochondrial dysfunction and ROS production, leading to widespread oxidative damage and activation of pro-apoptotic mechanisms. Past investigations suggest that neuronal resistance to Aβ toxicity is partly mediated by a Warburg Effect-like metabolism, in which cells exhibit elevated glycolytic activity and lactate production, while limiting mitochondrial respiration. Elevated lactate dehydrogenase A (LDHA) activity, which catalyzes lactate production from pyruvate, has been demonstrated to counter Aβ-induced oxidative stress and neurotoxicity, however the …

Seagrasses In The Age Of Sea Turtle Conservation And Shark Overfishing, Michael R. Heithaus, Teresa Allcoverro, Rohan Arthur, Derek Burkholder, Kathryn A. Coates, Marjolijn J.A. Christianen, Nachiket Kelkar, Sarah A. Manuel, Aaron J. Wirsing, W. Judson Kenworthy, James W. Fourqurean

Department of Biological Sciences

Efforts to conserve globally declining herbivorous green sea turtles have resulted in promising growth of some populations. These trends could significantly impact critical ecosystem services provided by seagrass meadows on which turtles feed. Expanding turtle populations could improve seagrass ecosystem health by removing seagrass biomass and preventing of the formation of sediment anoxia. However, overfishing of large sharks, the primary green turtle predators, could facilitate turtle populations growing beyond historical sizes and trigger detrimental ecosystem impacts mirroring those on land when top predators were extirpated. Experimental data from multiple ocean basins suggest that increasing turtle populations can negatively impact seagrasses, …

Recent Shifts In The Occurrence, Cause, And Magnitude Of Animal Mass Mortality Events, Samuel B. Fey, Adam M. Siepielski, Sébastien Nusslé, Kristina Cervantes-Yoshida, Jason L. Hwan, Eric R. Huber, Maxfield J. Fey, Alessandro Catenazzi, Stephanie M. Carlson

Dartmouth Scholarship

Mass mortality events (MMEs) are rapidly occurring catastrophic demographic events that punctuate background mortality levels. Individual MMEs are staggering in their observed magnitude: re- moving more than 90% of a population, resulting in the death of more than a billion individuals, or producing 700 million tons of dead biomass in a single event. Despite extensive documentation of individual MMEs, we have no understanding of the major features characterizing the occurrence and magnitude of MMEs, their causes, or trends through time. Thus, no framework exists for contextualizing MMEs in the wake of ongoing global and regional perturbations to natural systems. Here …

Rapidly Self-Renewing Human Multipotent Marrow Stromal Cells (Hmsc) Express Sialyl Lewis X And Actively Adhere To Arterial Endothelium In A Chick Embryo Model System, Harris E. Mcferrin, Scott D. Olson, Miriam V. Gutschow, Julie A. Semon, Deborah E. Sullivan, Darwin J. Prockop

Biological Sciences Faculty Research & Creative Works

Background: There have been conflicting observations regarding the receptors utilized by human multipotent mesenchymal bone marrow stromal cells (hMSC) to adhere to endothelial cells (EC). To address the discrepancies, we performed experiments with cells prepared with a standardized, low-density protocol preserving a sub-population of small cells that are rapidly self-renewing.

Methods: Sialyl Lewis X (SLeX) and α4 integrin expression were determined by flow cytometry. Fucosyltransferase expression was determined by quantitative realtime RT-PCR. Cell adhesion assays were carried out with a panel of endothelial cells from arteries, veins and the microvasculature in vitro. In Vivo experiments were performed to determine …

Increasing Energetic Cost Of Biosynthesis During Growth Makes Refeeding Deleterious, Chen Hou

Biological Sciences Faculty Research & Creative Works

Diet restriction (DR) enhances animals' health maintenance, but refeeding reverses its beneficial effects. However, to what degree refeeding reverses the beneficial effects of DR remains controversial. Here, I develop a theoretical model for reconciling the results of refeeding studies and understanding the dynamic and reversible mechanism underlying the effects of diet on health from the energetic viewpoint. By illustrating the negative correlation between health maintenance and the energetic cost of growth in animals under different diet regimes, the model explains why, in some cases, refed animals have better health and live longer than freely fed controls. More importantly, the model …