Life Sciences Commons^™

Beyond The Obvious: Emerging Contaminants And Biogeochemistry As A Cause And Solution For Nitrogen Pollution, Stephanie L. Devries

Dissertations, Theses, and Capstone Projects

Following a comprehensive review of the occurrence and impacts of antibiotics and related pharmaceutical compounds on the terrestrial N-cycle, three experiments were performed to explore the topic of biogeochemistry as a source or a sink for N-pollution. The first of these experiments addresses the question of whether environmentally relevant concentrations of antibiotics (µg·kg^-1) have a significant effect on denitrification or N₂O production, a question that has not been well addressed in previous studies. Having determined that there is a significant shift, the second study aims to comprehensively follow changes to soil N pools and N_{2 …}

Chloride And Proton Binding In The E. Coli 2cl¯:1h+ Clc Exchanger, Catherine Chenal

Dissertations, Theses, and Capstone Projects

The CLC family of membrane proteins is a ubiquitously expressed class of proton and usually voltage-activated chloride transporters involved in a myriad of physiological functions. Crystallographic structures identify up to three chloride binding sites: external, central and intracellular located in the inner half of the trans-membrane domain. The CLC proteins, except for the kidney isoforms, are gated by the extracellular side-facing gating Glutamate (Ex, E148 in CLC-ec1, the E. coli exchanger), which is thought to undergo a conformational change upon protonation.

To sort out how the thermodynamic paths to H+ coupled Cl¯ binding and conformational change in CLC-ec1 at the …

Environmental Changes Turn On The Sinorhizobium Melitloti Exor-Exos/Chvi (Rsi) Host Invasion Switch, Shari N. Walcott

Dissertations, Theses, and Capstone Projects

The free-living Gram-negative soil bacterium, Sinorhizobium meliloti, must switch into its host-invading form in order to infect the root hairs of the host plant, alfalfa (Medicago sativa), and establish a nitrogen-fixing symbiosis. The activation of the switch is believed to occur inside the infection chamber that is formed by curling of the root hairs. It is not fully understood what signals in the environment of the root hairs trigger and infection chamber S. meliloti to switch into a host-invading form since these signals were not extensively examined until now. This switch can be observed directly, due to …

Transcriptional And Post-Transcriptional Regulation Of Histone Variant H2a.Z During Sea Urchin Development, Mihai Hajdu

Dissertations, Theses, and Capstone Projects

Histone variant H2A.Z promotes chromatin accessibility at transcriptional regulatory elements and is developmentally regulated in metazoans. We characterize the transcriptional and post-transcriptional regulation of H2A.Z in the purple sea urchin Strongylocentrotus purpuratus. H2A.Z depletion by antisense translation-blocking morpholino oligonucleotides during early development causes developmental collapse, in agreement with its previously demonstrated general role in transcriptional multipotency. During H2A.Z peak expression in 24-h embryos, endogenous H2A.Z 3’ UTR sequences stabilize GFP mRNAs relative to those with SV40 3’ UTR sequences, although the 3’UTR of H2A.Z does not determine the spatial distribution of H2A.Z transcripts during embryonic and postembryonic development. We …

Impact Of Urbanization On Temperature Variation In Big Cities: Measuring Health Risk While Targeting Vulnerable Population, Maryam E. Karimi

Dissertations, Theses, and Capstone Projects

Densely populated cities are experiencing Urban Heat Island (UHI) effects and localized hotspots. Cities, such as New York can form heat islands all year round. This is primarily due to land surface modifications, radiative trapping in urban canyons and lack of cooling through evapotranspiration caused by displaced trees and vegetation. UHI refers to an increase in air and surface temperature in cities compared to surrounding suburban and rural areas. Large scale environmental forcing can cause subdivisions of UHI throughout a city. The combined of environmental forcing effects lead to the formation of hot pockets within the cities at micro-scale. The …

Therapeutic Exploitation Of Metabolic Checkpoints In Cancer Cells, Deven S. Patel

Dissertations, Theses, and Capstone Projects

During the G1 phase of the cell cycle, normal cells respond to growth factors and nutrients prior to entering S-phase to replicate its genome. We previously reported that the growth factor-mediated restriction point is distinguishable from a series of late G1 metabolic checkpoints mediated by essential amino acids (EAAs), the conditionally essential amino acid glutamine (Gln), and mTOR – the mammalian target of rapamycin. Mutations in genes encoding proteins that regulate G1 cell cycle progression are observed in virtually all cancers. We observed that cancer cells with K-Ras mutations bypass the late G1 Gln checkpoint when deprived of Gln and …

A Phylogenetic And Environmental Analysis Of Brazilian Placosoma Lizards, Kai A. Farje-Van Vlack

Dissertations and Theses

Placosoma is a genus comprised of the Brazilian spectacled lizards P. champsonotus, P. cipoense, P. cordylinum, P. glabellum, and P. limaverdorum. While P. champsonotus, P. cordylinum, and P. glabellum occupy the southern coast of Brazil, P. cipoense is found in the montane grasslands north of that range, and P. limaverdorum was recently discovered in forest isolates that persist within the semi-arid Caatinga. This study elucidates the ecological and evolutionary relationships among these morphologically similar lizards. Using mitochondrial and nuclear gene sequences, genus-wide phylogenies were inferred through Bayesian inference and a species tree approach, …

Enzymatically Active Microspheres For Self-Propelled Colloidal Engines, Jungeun Park

Dissertations and Theses

Micro- and nano-motors have attracted numerous attentions from various scientific areas due to their potential applications. Most studies on self-propelled colloidal engines have exploited catalytic decomposition of hydrogen peroxide to drive the motor. Since the hydrogen peroxide is caustic, it is not suitable to use in biological applications, encouraging people to develop “greener” fuels. The aim of this research is to study a new transduction mechanism for self-propulsion not tied to hydrogen peroxide, and which can in particular be used with biological molecules as fuels. In this study, we focus on making particles with enzymatic activity which can effectively decompose …

Are Weevils Picky Eaters? Community Structure And Host Specificity Of Neotropical Saproxylic Beetles (Coleoptera: Curculionidae), Jhunior A. Morillo

Dissertations and Theses

Abstract Primary saproxylic beetles play a major role in forest nutrient cycling and making deadwood accessible to other decomposers. Understanding beetle host preferences and patterns of community assembly is critical for their conservation, and for predicting which species might become invasive. This project aims to investigate the ecological and host specificity, as well as the community composition of curculionids in a mosaic of old-growth (OG) and secondary forest on the Osa Peninsula, Costa Rica. The subfamily Scolytinae was expected to be the most species-rich and abundant. Ambrosia beetles were expected to have more generalist species than other curculionids. Old growth …

Defining The Relationship Between Maternal Care Behavior And Hearing Development In Wistar Rats, Jingyun Qiu

Dissertations and Theses

Previous studies in rodents have demonstrated the profound effects that variations in maternal care play during the postnatal development of the brain. However, much less is known about how maternal care affects hearing development. Recently, manipulations of maternal care have been investigated to accelerate hearing onset. We hypothesized that accelerated hearing development results from changes in maternal care behavior. To test this hypothesis, we used a selection model in which natural variations in maternal care were identified in a large cohort of dams by measuring the frequency of different behaviors including LG followed by selection of dams with LG scores …