Cell Biology Commons^™

Decoupling Of Reproduction And Lifespan Trade-Off In Caenorhabditis Elegans Through Microbial Programming, Nora M. Villafuerte

LSU Master's Theses

The microbiome is increasingly recognized as a major regulator of host physiology. Using the Caenorhabditis elegans model, we investigated how natural commensal bacteria modulate host reproduction and lifespan through internal egg hatching, a phenotype in which retained embryos hatch within the maternal body. Screening strains from the CeMbio collection identified four focal strains Ochrobactrum BH3, Lelliottia JUb66, Pantoea BIGb0393, and Enterobacter CEent1 that significantly increased internal egg hatching during the late reproductive period. This contrasts with pathogenic bacteria, which induce early-onset internal egg hatching. Across the focal strains, worms exhibited reduced total brood size but an expanded reproductive window relative …

Role Of Cellular Stress Responses In Innate Immune Defense Against Acute Respiratory Infections, Amit Sharma

LSU Doctoral Dissertations

The endoplasmic reticulum (ER) stress sensor inositol-requiring enzyme 1α (IRE1α) is an important regulator of innate immune cells. However, its role in pulmonary innate host defenses remains poorly understood. This dissertation elucidates the dual, context-dependent role of IRE1α in host defense against methicillin-resistant Staphylococcus aureus (MRSA) pneumonia. We demonstrate IRE1α’s function as both a detrimental mediator of acute pathology and an essential facilitator of innate immune memory. Our work revealed that acute IRE1α activation during primary MRSA infection is detrimental. In lungs and alveolar macrophages (AMs), IRE1α is activated in response to MRSA infection. Consequently, IRE1α activation triggers a hyperinflammatory …

Metabolic And Physiological Regulation In C. Elegans: Insights Into Sperm Activation And Peroxisome-Mediated Longevity, Yash Flora

LSU Doctoral Dissertations

Organelle dynamics lie at the heart of cellular signaling and metabolic regulation, orchestrating physiological processes such as reproduction and aging across the lifespan. In this dissertation, I investigate how organelle-based signaling coordinates sperm activation and modulates organismal aging in the nematode Caenorhabditis elegans. I identify SPIN-4, a previously uncharacterized Spinster family transporter, as a key regulator of spermiogenesis. SPIN-4 is strongly expressed in developing sperm, localizes to the plasma membrane, and promotes sperm activation by facilitating the export of sphingosine-1-phosphate (S1P). Loss of spin-4 results in defective pseudopod formation, reduced motility, and compromised fertility, phenotypes that can be rescued …

Neuronal Cftr: A Study Of Subcellular Localization And Interactions With Implications For A Role In Synaptic Transmission, Brandon J. Leviskas

LSU Doctoral Dissertations

Protein-protein interactions vary among cell types and the localization of these interactions help to define protein function. The function of cystic fibrosis transmembrane conductance regulator (CFTR) is well established in the context of epithelial tissue due to the debilitating effects of its mutations that cause the disease cystic fibrosis. While in neurons a role has been established in our lab for CFTR in the regulation of cytosolic Cl- in retinal amacrine cells (ACs). This research sets out to learn if CFTR has a synaptic role. Exploring this potential role, localization of CFTR was examined using fluorescent and immunogold labeled transmission …

Metabolic Transitions In Embryos Of Artemia Franciscana: Regulation And Consequences For Oxidative Stress, Daniel Anthony Arabie

LSU Doctoral Dissertations

Embryos of Artemia franciscana survive harsh conditions in diapause and anoxia-induced quiescence for years by undergoing deep metabolic transitions. I investigated the relationship between phosphorylation of pyruvate dehydrogenase (PDH) and carbon flux to the tricarboxylic acid (TCA) cycle during metabolic depression. The difference in catalytic activity of the PDH complex (PDC) in maximally phosphorylated and dephosphorylated samples was 16.5-fold. Western blot analysis confirmed the changes in phosphorylation of PDH. Analysis of PDH expression in diapause and post-diapause embryos via phospho-PDH showed no significant differences. Investigation of post-diapause embryos under anoxia showed that phosphorylation of PDH decreased and activated the enzyme. …

The Role Of Siamese In G2 Checkpoint Regulation In Arabidopsis Thaliana, Martha A. Schwall

LSU Doctoral Dissertations

Cyclin-cyclin dependent kinase (Cyclin-CDK) pairs regulate progression through the checkpoints of the cell cycle. They bind with some specificity and must be bound to for their regulative properties to be active. The presence of cyclin-CDKs is conserved throughout eukaryotes, while differences in specifics exist between yeast, animals, and plants. In Arabidopsis, SIAMESE (SIM) is a CDK inhibitor that restricts progression through mitosis. Overexpression of SIM is required for endoreplication in Arabidopsis trichomes, and overexpression of SIM results in increased endoreplication in leaf epidermal cells. SIM is expressed at high levels in the root elongation zone, where it plays a …

A Comparison Of Diploid And Triploid Eastern Oysters For Aquaculture Production Under Extreme Temperatures And Salinities, Joshua H. Kim

LSU Master's Theses

Off-bottom aquaculture of Eastern oysters (Crassostrea virginica) is a nascent industry that is increasingly supported by the use of triploid oysters, which grow faster than diploids. Despite their growth advantage, elevated triploid mortality compared to diploids under high temperature, low salinity, or a combination of these conditions challenge consistent triploid production. Identifying the environmental thresholds at which differential triploid mortality occurs and predicting its economic impact are important to informing decision-making in oyster aquaculture. The goal of this thesis was to compare the biological and economic performance of diploid and triploid oysters under high temperature and low salinity conditions. …

Ammonium Chemotaxis In Chlamydomonas Reinhardtii, Gabela Nelson

LSU Doctoral Dissertations

Analysis of ammonium chemotaxis in Chlamydomonas reinhardtii is largely hindered, compared to that of phototaxis, despite equal importance on flagellated microalgal physiology. A major contribution of this shortfall is the lack of proper assay method. We developed a simple Petri dish assay method in which light is homogenously exposed while patterns of the cellular migration are tracked with a function of time. Using the method, new findings were revealed. First, this research presented that a strain lacking the eyespot organelle required for light gradient-sensing exhibits similar chemotactic behavior compared to a wild-type strain, suggesting Chlamydomonas sense an ammonium gradient not …

Influence Of Metabolic Interventions On Animal Aging And Lifespan, Bhaswati Ghosh

LSU Doctoral Dissertations

Aging is associated with metabolic rewiring. Most lifespan-extending longevity interventions target metabolic pathways. Genetic or pharmacological metabolic approaches that mediate longer lifespan and healthspan, are often linked to detrimental effects on human health. Here, I show that supplementation of botanical extracts from Artemisia scoparia (SCO), dramatically increases animal lifespan. Mechanistically, this lifespan extension is dependent on AMPK-DAF-16 signaling via inhibition of the insulin pathway. In SCO-fed worms, longer lifespan was accompanied by higher fat storage and improved resiliency to age-related physiological stress. Notably, DAF-16, the master regulator of longevity, activated the fatty acid desaturation processes, which promoted the accumulation of …

Svip Dependent Tubular Lysosomal Restoration: A New Direction In Vcp Diseases, Ankita Basu

LSU Doctoral Dissertations

Multisystem Proteinopathy-1 (MSP-1) is a rare, autosomal dominant, degenerative disease resulting from single amino acid mis-sense mutations in the AAA+ ATPase, Valosin containing protein (VCP). Patients with VCP mutations vary widely in their pathology and clinical penetrance, making it difficult to devise effective treatment strategies. To investigate the pathology of VCP- related disease, we engineered CRISPR knock-in Drosophila models for nine MSP-1 associated VCP mutations. These mutant animals mimic human MSP-1 disease phenotypes, including progressive mobility decline and accumulation of protein aggregates, making them excellent models to study the pathology of VCP associated mutations and test potential treatment strategies. At …

Establishing And Validating Methods To Assess The Influence Of Exercise On Circulating Exosome Profiles In Sedentary Older Adults, Heather Quiriarte

LSU Master's Theses

Aging is associated with progressing cellular structural and functional changes, and sedentary behavior can exacerbate these hallmarks of aging. Routine exercise is known to have beneficial effects on physiological systems, but the exact molecular mechanisms behind the health benefits are unclear. Emerging evidence suggests extracellular vesicles called exosomes are involved in the intercommunication between cells and organs following exercise by delivering their cargo such as proteins and miRNAs. miRNA profiles in older adults following acute and chronic exercise need further exploration. Specifically, the effects of regular low-intensity physical activity (LPA) breaks in sedentary time on proteins and miRNA packaged in …

The Effects Of Radical Containing Combustion Derived Particulate Matter In Adult Mouse Respiratory System, Jeffrey Harding

LSU Doctoral Dissertations

Epidemiological data associates high levels of combustion-derived particulate matter (PM) with deleterious respiratory outcomes, but the mechanism underlying those outcomes remains elusive. It has been acknowledged by the World Health Organization that PM exposure contributes to more than 4.2 million all-cause mortalities worldwide each year. Current literature demonstrates that PM exacerbates respiratory diseases, impairs lung function, results in chronic respiratory illnesses, and is associated with increased mortality. The proposed mechanisms revolve around oxidative stress and inflammation promoting pulmonary physiological remodeling. Our data demonstrate that environmentally persistent free radicals (EPFRs) stabilized on the surface of PM are capable of inducing oxidative …

Metabolic Network Analysis Of Filamentous Cyanobacteria, Daniel Alexis Norena-Caro

LSU Doctoral Dissertations

Cyanobacteria were the first organisms to use oxygenic photosynthesis, converting CO₂ into useful organic chemicals. However, the chemical industry has historically relied on fossil raw materials to produce organic precursors, which has contributed to global warming. Thus, cyanobacteria have emerged as sustainable stakeholders for biotechnological production. The filamentous cyanobacterium Anabaena sp. UTEX 2576 can metabolize multiple sources of Nitrogen and was studied as a platform for biotechnological production of high-value chemicals (i.e., pigments, antioxidants, vitamins and secondary metabolites). From a Chemical engineering perspective, the biomass generation in this organism was thoroughly studied by interpreting the cell as a microbial …

Insights Into Desiccation Tolerance: Properties Of Late Embryogenesis Abundant Proteins From Embryos Of Artemia Franciscana, Blase Matthew Leblanc

LSU Doctoral Dissertations

LEA proteins are a family of intrinsically disordered proteins that are expressed in various life stages of anhydrobiotic organisms and have been strongly associated with survival during water stress. The brine shrimp Artemia franciscana is the only known anhydrobiotic animal that expresses LEA proteins from Groups 1, 3, and 6. Here, I report that AfrLEA6, a novel Group 6 LEA protein, is most highly expressed in embryos during diapause and decreases throughout pre-emergence development. Notably, there is an acute drop in expression upon termination of the diapause state and the titer of AfrLEA6 during diapause is 10-fold lower than values …

Investigating The Role Of Torc1 And The Transcription Factor Sfp1p In The Regulation Of Hmo1 Gene In Saccharomyces Cerevisiae, Mathew Damien Smith

LSU Master's Theses

HMGB proteins are eukaryotic, chromatin-associated proteins that play roles in both DNA dynamics and transcription regulation. Hmo1p is an HMGB protein in Saccharomyces cerevisiae that behaves somewhat like a hybrid between mammalian HMGB proteins and the metazoan linker histone H1. mTORC1, a protein complex containing the Tor1p kinase and a major regulator of cellular growth, is inhibited by both rapamycin and stress. It has also been shown to not only associate with Hmo1p at various gene promoters, but also regulate the HMO1 gene itself through direct binding. In this study, the Hmo1p-mTORC1 relationship was further investigated through two questions: 1) …

Functions Of Cdk/Cyclin Complexes In Endoreplication Regulation By The Cdk Inhibitor Siamese, Kai Wang

LSU Doctoral Dissertations

Arabidopsis trichome (leaf hair) is a specialized single cell extended from epidermal cell on the leaves, which is a typical endoreplication and is also known as endoreduplication. Several D-type cyclins were tested to check the cell division in trichome, and the trichome expressing either CYCB1;2 or CDKB2;2 cannot trigger cell division, even if simultaneous expression of CYCB1;2 and CDKB2;2 failed to produce mitosis in trichome. Only CYCD3;1 specifically promotes multicellular trichome. cdkb1;1cdbk1;2 double mutants and sim cdkb1;1cdkb1;2 triple mutants exhibit the phenotype similar to the wild type and very limited cell division respectively. Overexpression of a CDKB1;1 dominant-negative construct that …

Dynamical Modeling In Cell Biology With Ordinary Differential Equations, Renee Marie Dale

LSU Doctoral Dissertations

Dynamical systems have been of interest to biologists and mathematicians alike. Many processes in biology lend themselves to dynamical study. Movement, change, and response to stimuli are dynamical characteristics that define what is 'alive'. A scientific relationship between these two fields is therefore natural. In this thesis, I describe how my PhD research variously related to biological, mathematical, and computational problems in cell biology. In chapter 1 I introduce some of the current problems in the field. In chapter 2, my mathematical model of firefly luciferase in vivo shows the importance of dynamical models to understand systems. Data originally collected …

Equine Hoof Stratum Internum K14+Cd105+ Progenitor Cells: Culture, Characterization, And Model Of Epithelial To Mesenchymal Transition, Qingqiu Yang

LSU Doctoral Dissertations

For the potential benefit of progenitor cells to be realized in cell-based clinical therapies, it is vital to investigate the mechanism between progenitor cells and abnormal tissue formation. Laminitis is a fatal condition that is often presented by equine hoof inflammation and hoof tissue disarrangement. The persistence of abnormal tissue formation after the resolution of equine laminitis suggests there is progenitor cell compromise. So far, there is limited information about equine hoof progenitor cells and the effects of inflammation on hoof progenitor cells. To pursue a better understanding of both hoof progenitor cell and hoof growth as well as find …

Divergent Transcriptional Regulation Of Suppressors Of Cytokine Signaling Genes In Adipocytes, Paula Mota De Sa

LSU Doctoral Dissertations

The Janus Kinase - Signal Transducer and Activator of Transcription (JAK-STAT) signaling pathway transduces several signals crucial for development and homeostasis. Suppressors of cytokine signaling (SOCS) proteins control JAK-STAT signaling via a negative feedback loop. The transcription factor STAT5 is known to play a significant role in fat cell development and function, and several studies suggest that acetylation may affect STAT5 transcriptional activity. To test this hypothesis, we treated 3T3-L1 adipocytes with growth hormone (GH) to activate STAT5 in the presence or absence of histone deacetylase (HDAC) inhibitors. STAT5 acetylation levels were low in adipocytes and mostly unchanged by the …

The Drosophila Neuroblasts: A Model System For Human Ribosomopathies, Sonu Shrestha Baral

LSU Doctoral Dissertations

This dissertation describes the use of Drosophila neuroblasts (NBs) to model human ribosomopathies; the overall goal is to understand why specific stem cell and progenitor cell populations are the primary targets in nucleolar stress as seen in the ribosomopathies. Chapter 1 provides an overview of relevant literature. Chapter 2 describes nucleolar stress in Drosophila neuroblasts as a model for human ribosomopathies. For this, we induce nucleolar stress by using the UAS-GAL4 system to express RNAi that depletes Nopp140 transcripts, and we also employ homozygous, CRISPR-Cas9-generated Nopp140 gene disruptions with a systemic null phenotype (Nopp140-/-). Embryonic lethality was observed …

Genome-Wide Screening Identifies Genes And Biological Processes Implicated In Chemoresistance And Oncogene-Induced Apoptosis, Tengyu Ko

LSU Doctoral Dissertations

Anti-proliferative responses such as senescence and apoptosis are often used by normal cells to combat oncogenic insults and to prevent tumorigenesis. However, oncogenic mutations are frequently found in cancers, suggesting that additional mutations may occur to facilitate the bypass of these anti-proliferative responses. It is believed that some of these additional mutations may also contribute to the chemoresistance of cancers. This dissertation focused on identifying novel genes and biological processes implicated in chemoresistance and tumorigenesis.

Cisplatin-based chemotherapeutic regimens are frequently used for treatments of solid tumors. However, tumor cells may have inherent or acquired resistance to cisplatin, and the underlying …

Conservation Of Freshwater Live-Bearing Fishes: Development Of Germplasm Repositories For Goodeids, Yue Liu

LSU Doctoral Dissertations

Fishes of the family Goodeidae are considered to be among the most imperiled taxa in the world. The goal of this project was to provide a foundation for development of sperm repositories for goodeids and to use them as a model to assist conservation programs for imperiled freshwater live-bearing fishes. Development of such repositories is challenging because of unusual reproductive characteristics of live-bearing fishes, such as sperm bundles, internal fertilization, and the bearing of live young. Standardized methods were established to evaluate quality-related attributes of sperm bundles. The different features between activation of free and bundled sperm were investigated and …

Exploring The Role Of Rna Polymerase Iii Complex Assembly On Ribosomal Dna Silencing In Saccharomyces Cerevisiae, Kyle Thomas Kern

LSU Doctoral Dissertations

The yeast rDNA region is host to a number of transcriptional regulatory elements, which work in conjunction to generate essential RNA subunits of ribosomes, as well as protecting the region from DNA damage. The role of RNA polymerase III complex binding at the 5S gene on rDNA silencing in the NTS2 region was investigated, both by use of a TY1:MET15 reporter insert and a MET15 gene integration at an endogenous SphI site. It was discovered that Pol III complexes do have an effect on reporter expression in the NTS2 region, though the specific effect was different based on the method …

5-Lipoxygenase (5-Lox)-5-Lipoxygenase Activating Protein (Flap)-Nanodisc Complex: A Model For The 5-Lox-Flap Interaction, Erin Elizabeth Schexnaydre

LSU Doctoral Dissertations

Leukotrienes (LT) are lipid mediators of the inflammatory response that play important roles in diseases such as asthma and atherosclerosis. Leukotriene A4 (LTA₄) is synthesized from arachidonic acid (AA) by 5-lipoxygenase (5-LOX) with the help of 5-lipoxygenase activating protein (FLAP), a trimeric nuclear transmembrane protein. Exactly how 5-LOX and FLAP interact is not well understood, however FLAP is essential for the production of leukotrienes in vivo. I used nanodiscs (NDs), engineered membrane systems, as a tool to study the 5-LOX-FLAP interaction. FLAP was incorporated into NDs with a phospholipid composition to mimic of the nuclear membrane. Structural features …

Effects Of Synthetic Histone Deacetylase Inhibitors On 3t3l1 Preadipocyte Adipogenic Differentiation Potential, Vikramjeet Singh

Honors Capstones

No abstract provided.

A Path To Success? A Review Of Evolution, Development, And The Predictable Genome By David L. Stern, Hope Hollocher, Charles H. Pence, Grant Ramsey, Michelle M. Wirth

Faculty Publications

No abstract provided.

Food Entrainment Of Circadian Gene Expression Altered In Pparα-/- Brown Fat And Heart, Brian Chun Kim Goh

Honors Capstones

No abstract provided.