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Theses/Dissertations

2014

Biochemistry, Biophysics, and Structural Biology

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Full-Text Articles in Life Sciences

Mechanisms Of Translational Repression Of The Sperm Mitochondria Associated-Cysteine Rich Protein (Smcp) Mrna In Round Spermatids, Danielle L. Cullinane Dec 2014

Mechanisms Of Translational Repression Of The Sperm Mitochondria Associated-Cysteine Rich Protein (Smcp) Mrna In Round Spermatids, Danielle L. Cullinane

Graduate Doctoral Dissertations

The sperm-mitochondria-associated cysteine-rich protein (SMCP) is a male germ cell-specific protein that localizes to the outer membranes of sperm mitochondria and increases sperm motility. The Smcp mRNA is transcribed in early spermatids, and stored in a translationally repressed state for ~7 days before translation is activated in late spermatids. Identifying the cis-elements and trans-factors that repress the Smcp mRNA in early spermatids is important because these factors and elements coordinate the translational activity of hundreds of mRNAs.

A mutation was studied in transgenic mice in which the 16 nucleotides downstream of the first poly(A) signal in the ...


Epigenetic Regulation Of Nuclear Hormone Receptor Dax-1, Michael B. Heskett Dec 2014

Epigenetic Regulation Of Nuclear Hormone Receptor Dax-1, Michael B. Heskett

Master's Theses

DAX-1 (NR0B1) is an orphan nuclear receptor that plays a key role in the development and maintenance of steroidogenic tissue in mammals. Dax-1 is also expressed in mouse embryonic stem (ES) cells and is required to maintain pluripotency. Duplication of the X-chromosome in the region containing the NR0B1 gene results in sex reversal, and mutations in NR0B1 cause adrenal hypoplasia congenita. DAX-1 has been observed to act as a corepressor of other nuclear receptors including androgen receptor (AR), estrogen receptor (ER), and steroidogenic factor 1 (SF-1). In addition to pluripotent ES cells, DAX-1 is primarily expressed in select tissues of ...


Mirage Dna Transposon Silencing By C. Elegans Condensin Ii Subunit Hcp-6: A Masters Thesis, Anna Malinkevich Dec 2014

Mirage Dna Transposon Silencing By C. Elegans Condensin Ii Subunit Hcp-6: A Masters Thesis, Anna Malinkevich

GSBS Dissertations and Theses

Mobile genetic elements represent a large portion of the genome in many species. Posing a danger to the integrity of genetic information, silencing and structural machinery has evolved to suppress the mobility of foreign and transposable elements within the genome. Condensin proteins – which regulate chromosome structure to promote chromosome segregation – have been demonstrated to function in repetitive gene regulation and transposon silencing in several species. In model system Caenorhabditis elegans, microarray analysis studies have implicated Condensin II subunit HCP-6 in the silencing of multiple loci, including DNA transposon MIRAGE. To address the hypothesis that HCP-6 has a direct function in ...


Chromatin Regulators And Dna Repair: A Dissertation, Gwendolyn M. Bennett Dec 2014

Chromatin Regulators And Dna Repair: A Dissertation, Gwendolyn M. Bennett

GSBS Dissertations and Theses

DNA double-strand break (DSB) repair is essential for maintenance of genome stability. However, the compaction of the eukaryotic genome into chromatin creates an inherent barrier to any DNA-mediated event, such as during DNA repair. This demands that there be mechanisms to modify the chromatin structure and thus access DNA. Recent work has implicated a host of chromatin regulators in the DNA damage response and several functional roles have been defined. Yet the mechanisms that control their recruitment to DNA lesions, and their relationship with concurrent histone modifications, remain unclear. We find that efficient DSB recruitment of many yeast chromatin regulators ...


Biological And Physiological Condition Of Juvenile California Halibut (Paralichthys Californicus) Exposed To A Contamination Gradient In Mission Bay, Ca, Kevin Stolzenbach Dec 2014

Biological And Physiological Condition Of Juvenile California Halibut (Paralichthys Californicus) Exposed To A Contamination Gradient In Mission Bay, Ca, Kevin Stolzenbach

Theses

Contaminated sediments in marine environments have been shown to be good indicators of ecological risk and a means to assess anthropogenic impacts on marine habitats and the animals that inhabit them (Long et al. 1995, Rattner 2009). Estuarine sediments are especially complex media with regard to physical, chemical, and biological characteristics that trap, store, modify and sometimes release contaminants to the biota (Long et al. 1995). Especially vulnerable are animals that are in constant contact with the sediments, such as flatfishes that partially bury themselves for camouflage (Costa et al. 2011). Impacts can be assessed in a number of ways ...


Development Of An Immunodiagnostic Assay For Canine Tear Lacritin, Alison Mae Enghauser Dec 2014

Development Of An Immunodiagnostic Assay For Canine Tear Lacritin, Alison Mae Enghauser

Senior Honors Projects, 2010-2019

Purpose: Lacritin is a naturally occurring human glycoprotein secreted from the lacrimal gland as a component of tears. Preliminary studies suggest that down-regulation of lacritin is associated with various ocular diseases, such as dry eye syndrome and blepharitis. Thus, lacritin shows potential as a new topical therapeutic for the treatment of ocular diseases. Previous studies have shown that recombinant human lacritin, when topically applied to rabbit eyes, promotes basal tearing. Antibodies produced against the terminal ends of human lacritin were used to develop a clinical immunodiagnostic assay that detect and quantify lacritin in human tear samples. In order to develop ...


Hcpe, A Potential Immuno-Modulatory Protein From Helicobacter Pylori That Is Dependent On The Disulfide Bond Protein Dsbhp, Jeff Lester Dec 2014

Hcpe, A Potential Immuno-Modulatory Protein From Helicobacter Pylori That Is Dependent On The Disulfide Bond Protein Dsbhp, Jeff Lester

Electronic Thesis and Dissertation Repository

H. pylori is a human gastric pathogen that colonizes ~ 50% of the world’s population. It can cause gastritis, gastric or duodenal ulcers and also gastric cancer. H. pylori produces Helicobacter cysteine rich protein HcpE, a secreted protein which may play a role in virulence. In this study we show that HcpE is secreted in the culture supernatant both as a soluble protein and in association with outer membrane vesicles, and may play a role in the modulation of H. pylori inflammatory responses. We identified that DsbHP is necessary for HcpE production and secretion in H. pylori, and demonstrated ...


The Recombination Enhancer Modulates The Conformation Of Chr. Iii In Budding Yeast: A Dissertation, Jon-Matthew Belton Dec 2014

The Recombination Enhancer Modulates The Conformation Of Chr. Iii In Budding Yeast: A Dissertation, Jon-Matthew Belton

GSBS Dissertations and Theses

A hierarchy of different chromosome conformations plays a role in many biological systems. These conformations contribute to the regulation of gene expression, cellular development, chromosome transmission, and defects can lead to human disease. The highest functional level of this hierarchy is the partitioning of the genome into compartments of active and inactive chromatin domains (1’s -10’s Mb). These compartments are further partitioned into Topologically Associating Domains (TADs) that spatially cluster co-regulated genes (100’s kb – 1’s Mb). The final level that has been observed is long range loops formed between regulatory elements and promoters (10’s kb ...


Novel Mechanisms In The Sorting Of Proglucagon To The Secretory Granules Of The Regulated Secretory Pathway, Leonard M. Guizzetti Dec 2014

Novel Mechanisms In The Sorting Of Proglucagon To The Secretory Granules Of The Regulated Secretory Pathway, Leonard M. Guizzetti

Electronic Thesis and Dissertation Repository

The prohormone proglucagon encodes for multiple peptide hormones, including glucagon, glucagon-like peptide-1 (GLP-1), and GLP-2, produced through tissue-specific processing by prohormone convertase (PC) 1/3 and PC2. In alpha cells, PC2 yields glucagon, the major counter-regulatory hormone to insulin, which together, control glucose homeostasis. In contrast, GLP-1 and GLP2 are mainly produced in intestinal L-cells by PC1/3. GLP-1 stimulates insulin secretion following a meal, and therefore has opposing function to glucagon regulating glucose homeostasis; in contrast, GLP-2 enhances gut nutrient absorption. Efficient sorting of proglucagon to secretory granules is required for nutrient-regulated secretion. The aim of this thesis is ...


The Role Of Nag-1 In Tumorigenesis, Kyung-Won Min Dec 2014

The Role Of Nag-1 In Tumorigenesis, Kyung-Won Min

Doctoral Dissertations

This dissertation explores the nature of a divergent member of the Transforming Growth Factor-β [beta] superfamily, the non-steroidal anti-inflammatory drugs activated gene (NAG-1), as it relates to its regulation and biological activity in cancer context. Our lab has extensively studied on the molecular mechanism by which phytochemicals and NSAIDs induce apoptosis correlation with NAG-1 expression in human colorectal cancer (CRC) cells. Significant data from in vitro studies suggest that NAG-1 has an anti-tumorigenic activity which elicits apoptosis in a cyclooxygenase (COX)-independent manner in CRC cells. Indeed, NAG-1 transgenic mice developed less aberrant polyp foci (APC) compared to those of ...


Comparative Genomics Of Microbial Chemoreceptor Sequence, Structure, And Function, Aaron Daniel Fleetwood Dec 2014

Comparative Genomics Of Microbial Chemoreceptor Sequence, Structure, And Function, Aaron Daniel Fleetwood

Doctoral Dissertations

Microbial chemotaxis receptors (chemoreceptors) are complex proteins that sense the external environment and signal for flagella-mediated motility, serving as the GPS of the cell. In order to sense a myriad of physicochemical signals and adapt to diverse environmental niches, sensory regions of chemoreceptors are frenetically duplicated, mutated, or lost. Conversely, the chemoreceptor signaling region is a highly conserved protein domain. Extreme conservation of this domain is necessary because it determines very specific helical secondary, tertiary, and quaternary structures of the protein while simultaneously choreographing a network of interactions with the adaptor protein CheW and the histidine kinase CheA. This dichotomous ...


Interaction Of Rhizobium Sp. Strain Irbg74 With A Legume (Sesbania Cannabina) And A Cereal (Oryza Sativa), Shubhajit Mitra Dec 2014

Interaction Of Rhizobium Sp. Strain Irbg74 With A Legume (Sesbania Cannabina) And A Cereal (Oryza Sativa), Shubhajit Mitra

Theses and Dissertations

Rhizobium sp. IRBG74 (IRBG74) develops a classical nitrogen-fixing symbiosis with the legume Sesbania cannabina and also promotes the growth of rice (Oryza sativa), but not much is known about the rhizobial determinants important for these interactions. We hypothesize that Rhizobium sp. IRBG74 utilizes similar mechanisms to endophytically colonize both legume and cereal hosts. In this study, we analyzed the colonization of rice and S. cannabina using a strain of IRBG74 marked with β-glucuronidase (GUS) and Green Fluorescent Protein (GFP). IRBG74 infected both of the host plants through crack entry under submerged conditions, but showed root hair mediated infection under aerobic ...


Measuring The Role Of Inhibition In Auditory Discrimination In Mice, Tazima Nur Dec 2014

Measuring The Role Of Inhibition In Auditory Discrimination In Mice, Tazima Nur

Theses and Dissertations

Understanding how inhibitory neurons affect sensory information processing in the cerebral cortex is an ongoing goal of both neuroscience and statistical physics research. In this master's thesis research project, an experimental system has been designed and built for studying how auditory dynamic range depends on inhibitory neurons, based on observations of mouse behavior. In this thesis, firstly, the topic of inhibition and information processing has been introduced. Then two papers related to inhibition and dynamic range has been reviewed in detail. One of the papers is an experimental work that analyzes the affect of inhibition on dynamic range. The ...


Cellular Zinc Trafficking: The Zinc Proteome And Its Reactions With Cadmium, Mohammad Ali Namdarghanbari Dec 2014

Cellular Zinc Trafficking: The Zinc Proteome And Its Reactions With Cadmium, Mohammad Ali Namdarghanbari

Theses and Dissertations

Metals play a crucial role in living systems. Iron, zinc, copper, molybdenum, and manganese are involved in many essential biological activities. Among transition metals, zinc after iron is the most abundant transition metal in the human body and the most abundant in the brain. It exists in more than 3000 proteins, which comprise about 10% of the human proteome. Zn2+ dyshomeostasis is associated with chronic diseases such as metabolic syndrome, diabetes and related complications, bone loss, growth retardation in young children, and neurological and behavioral problems. Despite a good knowledge obtained for metabolism of some metal ions such as copper ...


Novel Protein Secretion And Chitin Utilization Machinery Of Flavobacterium Johnsoniae, Sampada Suresh Kharade Dec 2014

Novel Protein Secretion And Chitin Utilization Machinery Of Flavobacterium Johnsoniae, Sampada Suresh Kharade

Theses and Dissertations

Flavobacterium johnsoniae, a member of phylum Bacteroidetes, is a gliding bacterium that digests insoluble chitin. A novel protein secretion system, the Type IX secretion system (T9SS), secretes the motility adhesins SprB and RemA and is also required for chitin utilization. In order to understand F. johnsoniae chitin utilization and the role of the T9SS, Fjoh_4555 (chiA) was targeted for analysis. Disruption of chiA resulted in cells that failed to digest chitin and complementation restored this ability. Antisera raised against ChiA were used to characterize its secretion. ChiA was secreted in soluble form by wild-type cells but remained cell-associated in T9SS ...


Oligomerization Of The Sterile-2 G-Protein Coupled Receptor In Yeast Cells In The Presence And Absence Of Alpha-Factor Pheromone Using Fluorescence Spectroscopy And Forster Resonance Energy Transfer Analysis, Joel David Paprocki Dec 2014

Oligomerization Of The Sterile-2 G-Protein Coupled Receptor In Yeast Cells In The Presence And Absence Of Alpha-Factor Pheromone Using Fluorescence Spectroscopy And Forster Resonance Energy Transfer Analysis, Joel David Paprocki

Theses and Dissertations

G-protein-coupled receptors (GPCRs) are the largest family of receptors that respond to a wide variety of extracellular stimuli, including molecular ligands such as odorants, neurotransmitters, and hormones, as well as physical agents sigh as light and pressure. The stimulation event results in initiating conformational changes in the structure of the receptor, which further results in the release of the heterotrimeric G-protein; the latter has a variety of functions within signaling pathways in cellular biology. The GPCR explored in this investigation is the Sterile 2 α-factor receptor (Ste2), whose natural function is that of a yeast mating pheromone receptor. Its natural ...


Computer Simulations Of Enzymes, Jianzhuang Yao Dec 2014

Computer Simulations Of Enzymes, Jianzhuang Yao

Doctoral Dissertations

Enzymes are important catalysts in living systems, and understanding catalytic mechanisms of enzymes is an important task for modern biophysics and biochemistry. Computer simulations have emerged as very useful tools for understanding how enzymes work. In this dissertation, QM/MM MD simulations were applied to study the catalytic mechanisms of several enzymes, including sedolisin, S-adenosyl-L-methionine (AdoMet)-dependent methyltransferases, and salicylic acid binding protein 2. For sedolisin, we focus on the acylation and deacylation reactions catalyzed by the enzymes. We proposed a general acid/base mechanism involving the Glu/Asp residues at the active site. MD and QM/MM free energy ...


Pore Selectivity And Gating Of Arabidopsis Nodulin 26 Intrinsic Proteins And Roles In Boric Acid Transport In Reproductive Growth, Tian Li Dec 2014

Pore Selectivity And Gating Of Arabidopsis Nodulin 26 Intrinsic Proteins And Roles In Boric Acid Transport In Reproductive Growth, Tian Li

Doctoral Dissertations

Plant nodulin-26 intrinsic proteins (NIPs) are members of the aquaporin superfamily that serve as multifunctional channels of uncharged metabolites and water. They share the same canonical hourglass fold as the aquaporin family. The aromatic arginine (ar/R) selectivity filter controls transport selectivity based on size, hydrophobicity, and hydrogen bonding with substrates. In Arabidopsis thaliana, NIP II subclass proteins contain a conserved ar/R “pore signature” that is composed of Alanine at the helix 2 position (H2), Valine/Isoleucine at the helix 5 position (H5), and an Alanine (LE1) and an invariant Arginine (LE2) at the two loop E positions. In ...


The Dissolution Of Cellulose In Ionic Liquids - A Molecular Dynamics Study, Barmak Mostofian Dec 2014

The Dissolution Of Cellulose In Ionic Liquids - A Molecular Dynamics Study, Barmak Mostofian

Doctoral Dissertations

The use of ionic liquids for the dissolution of cellulose promises an alternative method for the thermochemical pretreatment of biomass that may be more efficient and environmentally acceptable than conventional techniques in aqueous solution. Understanding how ionic liquids act on cellulose is essential for improving pretreatment conditions and thus detailed knowledge of the interactions between solute and solvent molecules is necessary. Here, results from the first all-atom molecular dynamics simulation of an entire cellulose microfibril in 1-butyl-3-methylimidazolium chloride (BmimCl) are presented and the interactions and orientations of solvent ions with respect to glucose units on the hydrophobic and hydrophilic surfaces ...


Gene Regulatory Pathways Driving Central Nervous System Regeneration In Zebrafish, Ishwariya Venkatesh Dec 2014

Gene Regulatory Pathways Driving Central Nervous System Regeneration In Zebrafish, Ishwariya Venkatesh

Theses and Dissertations

Damage to the central nervous system (CNS) circuitry of adult mammals results in permanent disability. In contrast, the ability to regenerate damaged CNS nerves and achieve functional recovery occurs naturally in fish. The ability of fish to successfully regrow damaged CNS nerves is in part a consequence of their ability to re-express key neuronal growth-associated genes/proteins in response to CNS injury. On such protein is Growth-Associated Protein-43 (Gap43), a protein which is highly enriched in axonal growth cones during CNS development and regeneration. Experiments conducted in mammals have demonstrated that ectopic expression of GAP-43 improves axonal re-growth after injury ...


Modulation Of T Lymphocytes By Tumor-Released Survivin, Jessica Marie Jutzy Dec 2014

Modulation Of T Lymphocytes By Tumor-Released Survivin, Jessica Marie Jutzy

Loma Linda University Electronic Theses, Dissertations & Projects

The tumor microenvironment is an area of intense interaction between normal and malignant cells. Factors and cell types within this environment can play a crucial role in the progression or regression of the tumor. Of primary interest are tumor-infiltrating T lymphocytes, which have been shown to have a key role in modifying the dynamics of the tumor microenvironment to promote or prevent tumor growth. While there is much in vitro and in vivo evidence for a modification of the tumor infiltrating T cell population toward a pro-tumor environment, what induces these changes within the tumor microenvironment has remained elusive. Our ...


Effects Of Water Column P-Availability And Litter Microbial Mediated Processes And Stoichiometry In Aquatic Systems, Ayla Smartt Dec 2014

Effects Of Water Column P-Availability And Litter Microbial Mediated Processes And Stoichiometry In Aquatic Systems, Ayla Smartt

Theses and Dissertations

Anthropogenic nutrient enrichment of aquatic ecosystems is prevalent and can have detrimental effects on biological condition. Many of these effects have been attributed directly or indirectly to changes in autotrophic processes. However, in detrital-based streams changes in course detrital stoichiometry and decomposition have been related to changes community structure and production at higher trophic levels highlighting the importance of considering the heterotrophic microbial responses to enrichment. Leaf litter stoichiometry, which is determined in part by the tree species source and the microbial communities that comprise the associated biofilm, is likely related to decomposition rates, but few studies examine these variables ...


The Mechanism Of Lhcp Insertion Into Thylakoid Membranes, Larae Brown Dec 2014

The Mechanism Of Lhcp Insertion Into Thylakoid Membranes, Larae Brown

Theses and Dissertations

The light harvesting chlorophyll a/b-binding proteins (LHCPs) are the most abundant membrane proteins. LHCP is a nuclear encoded protein which is targeted to the thylakoid membranes by chloroplast signal recognition particles (cpSRP). Insertion into thylakoid membranes is facilitated by the cpSRP receptor cpFtsY and the Alb3 translocase. Work here focused on understanding the molecular events of LHCP insertion into the thylakoid membranes. Specifically, we sought to develop a tool to detect the insertion of the lumen-localized loop of LHCP into thylakoid membranes, which relies on cleavage of the loop by a thylakoid lumen processing protease. We also sought to ...


Investigation Of Nuclear And Cytoplasmic Functions Of The Dlipin Protein Of Drosophila Melanogaster, Qiuyu Chen Dec 2014

Investigation Of Nuclear And Cytoplasmic Functions Of The Dlipin Protein Of Drosophila Melanogaster, Qiuyu Chen

Theses and Dissertations

Lipin family proteins are highly conserved proteins present in species ranging from mammals to yeast. Lipin 1, the first Lipin gene identified in fatty liver dystrophy (fld) mutant mice, encodes the bifunctional protein Lipin 1, which can serve as an Mg2+-dependent phosphatidic acid phosphatase (PAP) and transcriptional co-regulator. dLipin, the single Lipin ortholog of Drosophila melanogaster, is required in triglyceride synthesis and fat body development. To study the transcriptional co-regulator activity of dLipin, nuclear receptors were screened to find receptors that interact with dLipin. The genetic interaction data indicated that Drosophila hepatic nuclear receptor 4 (HNF4) was a promising ...


Characterization And Role Of Msaabcr In Biofilm Development And Virulence In Staphylococcus Aureus, Gyan Sundar Sahukhal Dec 2014

Characterization And Role Of Msaabcr In Biofilm Development And Virulence In Staphylococcus Aureus, Gyan Sundar Sahukhal

Dissertations

Community-acquired, methicillin-resistant Staphylococcus aureus strains often cause localized infections in immune-compromised hosts, but some strains show enhanced virulence leading to severe infections even among healthy individuals with no predisposing risk factors. The genetic basis for this enhanced virulence has yet to be determined. S. aureus possesses a wide variety of virulence factors, the expression of which is carefully coordinated by a variety of regulators. Several virulence regulators have been well characterized, but others have yet to be thoroughly investigated. Previously, the msa gene as a regulator of several virulence genes, biofilm development, and antibiotic ...


Melatonin And Neurogenesis: A Comparative Study Of The Efficacy Of Melatonin, Its Precursors, And L-Dopa On Neural Stem Cell Metabolism In Human Adult Neurospheres, Omar Heriba Dec 2014

Melatonin And Neurogenesis: A Comparative Study Of The Efficacy Of Melatonin, Its Precursors, And L-Dopa On Neural Stem Cell Metabolism In Human Adult Neurospheres, Omar Heriba

HIM 1990-2015

Human neurosphere stem cells offer promising potential for the treatment of neurodegenerative diseases. Their well characterized multi-potency of differentiating into neurons, astrocytes, and oligodendrocytes when exposed to the optimum exogenous growth factors make them an exciting area of study (38). Finding novel endogenous methods of modulating stem cell metabolism will allow for the safer treatment of various brain disorders (34). In this experiment, melatonin, N-acetylserotonin, L-tryptophan, and L-DOPA are added in three different concentrations to neurospheres suspended in HNSC/GBM media with less than optimal concentrations of exogenous epidermal growth factor (EGF) and fibroblast growth factor (FGF). The alamarBlue assay ...


Allosteric Regulation Of Bacterial And Fungal Xylulose 5-Phosphate/ Fructose 6-Phosphate Phosphoketolases (Xfps), Katie Glenn Dec 2014

Allosteric Regulation Of Bacterial And Fungal Xylulose 5-Phosphate/ Fructose 6-Phosphate Phosphoketolases (Xfps), Katie Glenn

All Dissertations

Acetate is excreted as a metabolic end product in many microbes. Acetate production has primarily been studied in bacteria and archaea but is known to occur in eukaryotic organisms as well. For example, acetate is one of the most abundant metabolites excreted by the fungal pathogen Cryptococcus neoformans during cryptococcosis suggesting that acetate production may be important during pathogenesis. One possible pathway for acetate production in C. neoformans involves the enzymes xylulose 5-phosphate/ fructose 6-phosphate phosphoketolase (Xfp), which can generate acetyl phosphate from either fructose 6-phosphate (F6P) or xylulose 5-phosphate (X5P), and acetate kinase (Ack), which can then convert acetyl ...


A Step Towards Understanding Of The Molecular Basis Of Ligand Promiscuity In The Aminoglycoside Modifying Enzymes, Sherin R. Raval Dec 2014

A Step Towards Understanding Of The Molecular Basis Of Ligand Promiscuity In The Aminoglycoside Modifying Enzymes, Sherin R. Raval

Masters Theses

Aminoglycosides have proven very useful in the treatment of infections; lately their effectiveness has been greatly reduced due to increasing resistance. Among many known mechanisms of resistance to aminoglycosides, enzymatic modification is the most prevailing. More than 14 aminoglycoside -N3-acetyltransferases- a class of aminoglycoside modifying enzymes, are known today. This study focuses on a pair of acetyl transferases: The aminoglycoside-N3- acetyltransferase IIIb (AAC-IIIb) and the aminoglycoside-N3- acetyltransferase IIa (AAC-IIa). AAC-IIa and AAC-IIIb are very similar in their amino acid sequence and structure – yet they have a strong difference in their substrate selectivity, kinetic and thermodynamic properties. This ...


Localization Of Chemoreceptors In Azospirillum Brasilense., Anastasia Aksenova Dec 2014

Localization Of Chemoreceptors In Azospirillum Brasilense., Anastasia Aksenova

Masters Theses

In order to ensure their survival, bacteria must sense and adapt to a variety of environmental signals. Motile bacteria are able to orient their movement in a chemical gradient by chemotaxis. During chemotaxis, environmental signals are detected by chemotaxis receptors and are propagated via a signal transduction cascade to affect bacterial motility. In a model organism Escherichia coli, chemotaxis receptors, also called MCPs (for methyl-accepting chemotaxis proteins) sense changes in concentration gradients by making temporal comparisons about the chemical composition of their surroundings. Decreased attractant concentration or increased repellant concentration results in conformational changes in the MCPs that culminate in ...


Functional Characterization Of The Arginine Vasotocin 4 Receptor (Vt4r) In Sensory Circumventricular Organs Of The Chicken Gallus Gallus, Nguiessan Alphonse Aman Dec 2014

Functional Characterization Of The Arginine Vasotocin 4 Receptor (Vt4r) In Sensory Circumventricular Organs Of The Chicken Gallus Gallus, Nguiessan Alphonse Aman

Theses and Dissertations

Past studies have shown that the avian vasotocin 4 receptor (VT4R), homologous to the mammalian arginine vasopressin receptor 1a (V1aR/AVPR1A) is involved in immobilization stress. It was not known, however, whether the receptor is also associated with osmotic stress, and if so, what brain regions may be involved. Four treatment groups of chicks were used for the study. One group was subjected to 1h immobilization stress and two groups were administered intraperitoneal injection of 3 M NaCl or 0.15 M NaCl. One additional group served as controls. After 1 h, blood samples were taken for the determination of ...