Showing 11 - 20 of 67 Items
Investigating the role of eyes absent in photoreceptor axon targeting in Drosophila melanogaster
Date: 2021-01-01
Creator: Bethany J. Thach
Access: Open access
- The eya gene is essential to development of the Drosophila visual system and eye-specific loss of function mutations in the gene commonly result in the missing eye phenotype. The eya2m35g mutation carries a deletion of exon 1B and adjacent regulatory sequences. Flies carrying the eya2m35g allele exhibit a photoreceptor axon phenotype that has not previously been associated with the eya gene. To determine a potential role for eya in photoreceptor axon targeting, I characterized various phenotypes of eya2m35g mutants and generated additional eya alleles consisting of smaller deletions within the eya2m35g mutation to locate the genetic source of axonal disruption. Using immunofluorescence staining to visualize Eya protein, I found a loss of eya expression in the optic lobe region of eya2m35g stage 9 embryos and third instar larvae. I also observed a loss of retinal basal glial (RBG) cells in the larval eye disc. Finally, I demonstrated that the disconnected axon phenotype is generated when a region of the intron immediately downstream of exon 1B is deleted. These findings suggest that a possible regulatory element for eya that is essential for photoreceptor axon targeting exists in this intronic region.
Antimicrobial Compounds in the Lobster, Homarus americanus: An Investigation of Lobster Shell Extracts This record is embargoed.
- Embargo End Date: 2027-05-19
Date: 2022-01-01
Creator: Usira Ahmed Ali
Access: Embargoed
Chromatin-conformation differences in natural populations of D. melanogaster Access to this record is restricted to members of the Bowdoin community. Log in here to view.
- Restriction End Date: 2026-06-01
Date: 2021-01-01
Creator: Nicholas J. Purchase
Access: Access restricted to the Bowdoin Community
The Photocatalytic Degradation of Ibuprofen and Atenolol Using Bismuth Oxychloride and Titanium Dioxide
Date: 2021-01-01
Creator: Kamyron Anthony Speller
Access: Open access
- Pharmaceuticals and personal care products (PPCPs) are contaminating natural bodies of water and are problematic for aquatic organisms and ecosystems. Generally, PPCPs are introduced to water systems due to incomplete removal by wastewater treatment plants (WWTPs). As such, it is vital to find ways to remediate these problematic contaminants before they are discharged into the environment. In this study, two photocatalysts¾titanium dioxide (TiO2) and bismuth oxychloride (BiOCl)¾were compared to determine their relative efficiencies (degradation rates) and dominant degradation mechanism (hydroxyl radical production or direct oxidation) with the goal of photocatalytically degrading two pharmaceuticals, atenolol and ibuprofen, using UV (254 nm) light. While TiO2 has been used extensively for photocatalytic degradation, BiOCl is a newer photocatalyst. The two pharmaceuticals selected for study represent two large classes of drugs (aryloxypropanolamine and propionic acid derivatives, respectively) that have been detected in the influent into and effluent from wastewater treatment plants and in the environment. When irradiated at 254 nm, BiOCl degrades ibuprofen with a rate constant 15 times greater than TiO2. On the other hand, TiO2 degrades atenolol with a rate constant 2.2 times greater than BiOCl. LCMS analysis of photodegradation products reveals different products produced by the two photocatalysts, providing evidence for the dominance of different degradation mechanisms for the two photocatalysts. In summary, this work suggests that BiOCl, potentially used in combination with TiO2, holds potential for degrading PPCPs in natural bodies of water.
Semaphorin-Induced Plasticity in the Nervous System of the Cricket, Gryllus bimaculatus
Date: 2021-01-01
Creator: Alicia G. Edwards
Access: Open access
- The adult auditory system of the cricket, Gryllus bimaculatus, exhibits a rare example of neuronal plasticity. Upon deafferentation, we observe medial dendrites that normally respect the midline of the PTG in the central nervous system sprouting across the boundary and forming synaptic connections with the contralateral auditory afferents. The Horch Lab has investigated key molecular factors that might play a causal role in this paradigm. Specifically, the protein Sema1a.2 comes from a guidance molecule family and has a role in developmental neuronal plasticity in other organisms. In this study, I explored the role of Sema1a.2 in the neuronal plasticity of the adult auditory system of the cricket by conducting a series of dsRNA knockdown experiments targeting Sema1a.2 followed by backfill procedures in which we iontophoresed dye into the Ascending Neurons (ANs) to visualize the anatomical effects of the knockdown experiments using confocal microscopy. We found that there were no significant differences between animals injected with dsRNA against GFP and Sema1a.2 volume, with respect to qualitative and quantitative data. However, we believe with an increase in cohort size, the trends observed, particularly the effect of Sema1a.2 knockdowns on CWM and CBM volumes, will become more pronounced and significant. Potential future pathways could include conducting double knockdowns of Sema1a.2 and Sema2a to observe if these two proteins are working together to create a more obvious effect on midline crossing and branching. Other options also include looking into other protein families that might be the causing factor in this rare phenomenon (toll-like receptors).
Examining the Effect of Aromatic Substituents in Peptoid Catalysts of Stereoselective Trifluoromethylation Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2024-01-01
Creator: Daniel Chi
Access: Access restricted to the Bowdoin Community
Synthesis of N-Heterocyclic Carbene Complexes of Coinage Metals and Their Application in the Activation of Hydrogen
Date: 2024-01-01
Creator: Maryam Akramova
Access: Open access
- The main cause of the ongoing global climate crisis is the emission of greenhouse gases, and current climate reports emphasize the need to transition to low-emission renewable energy sources. Urgently needed are methods for storing renewable energy, such as synthetic fuels like hydrogen (H2) gas; however, a challenge to the widespread implementation of hydrogen fuel is its low volumetric energy density. This thesis describes an effort to synthesize a catalyst that takes advantage of hard-soft acid-base (HSAB) mismatches to activate H2 and facilitate its reaction with CO2 to form hydrocarbon fuels, thereby providing a sustainable means of storing renewable energy in high-density carbon-neutral fuels. The catalyst design features an exceptionally bulky N-heterocyclic carbene (NHC) ligand known as IPr** (3-Bis[2,6-bis[bis(4-tert-butylphenyl)methyl]-4-methylphenyl]-1H-imidazol-3-ium chloride), a coinage metal acting as a soft acid, and a hard base such as an alkoxide ion. Herein is reported a modified synthetic route of IPr**, along with its metalation with silver, and preliminary results of the addition of an alkoxide base. The ligand and its complex with silver are structurally characterized by nuclear magnetic resonance (NMR) spectroscopy. Further work is needed to complete the characterization of IPr**-supported HSAB mismatch complexes and investigate their potential to activate H2.
Cell Adhesion in Arabidopsis thaliana Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2019-05-01
Creator: Natasha Ann Belsky
Access: Access restricted to the Bowdoin Community
The role of the ROG1 protein in pectin perception Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2014-05-01
Creator: Divya Hoon
Access: Access restricted to the Bowdoin Community
Genetic Analysis of Adhesion Protein ELMO3 in Arabidopsis thaliana
Date: 2022-01-01
Creator: Garrison Asper
Access: Open access
- The Extracellular Matrix (ECM) between plant cells is vital for structure, development, and intercellular adhesion. A pectin rich layer in between cells, the middle lamella, is largely responsible for regulating the adhesive properties of adjacent plant cells. Homogalacturonan (HG) pectin, the most common, is synthesized in the Golgi and secreted into the ECM where it undergoes calcium crosslinking, increasing its adhesive properties. Mutations in proteins essential for HG synthesis can reveal a severe adhesion defective phenotype, where the hypocotyls of dark grown Arabidopsis exhibit cell sloughing, curling, and general disorganization. A family of five ELMO proteins are suspected to act as scaffolds for pectin biosynthesis enzymes. ELMO1 and ELMO4 mutants exhibit an adhesion deficient phenotype, and a double mutant provides evidence of redundancy in function between ELMO1 and ELMO2. ELMO1-GFP co-immunoprecipitated with enzymes required for HG synthesis indicating its role as a scaffold protein. Double mutants of the other ELMO homologues were created to determine if they exhibit functional redundancy, and ELMO1 and ELMO3 appear partially redundant. A gene deletion of ELMO3 was also created using the CRSPR/Cas9 system, resulting in two distinct elmo3 deletion alleles, which were phenotypically identical to the original elmo3-/- mutant. All adhesion defective phenotypes can be partially suppressed by altering the osmoticum and hence turgor that provides pressure on adhesive cells. Lastly, ELMO3-GFP was localized to the Golgi, the site of pectin biosynthesis, further supporting a common role of the ELMOs in pectin biosynthesis.