Genetics and Genomics Commons^™

The Design And Validation Of A Qpcr-Based Approach To Cell Quantification Of Fungal-Algal Symbioses, Isabelle Katherine Garlotte

Honors Theses

Symbiotic relationships are extremely common in virtually all species. These relationships between organisms, particularly mutualistic symbioses, can have an incredibly large impact and can greatly affect the evolution of the species involved. Of particular interest is the suspected mutualistic relationship between green algae and fungi that may hold key evidence of how terrestrial plants evolved. In this experiment we established a method of quantifying the cells of each species involved in these symbioses through qPCR analysis to determine if the relationships are truly mutualistic. We developed a system for using DNA copies as a proxy for cell count in co-cultures …

Neogene And Quaternary Events Shaped Diversification And Speciation In Bhutanese Rheophilic Fishes Of The Family Nemacheilidae (Cypriniformes) And Sisoridae (Siluriformes), Karma Wangchuk

Graduate Theses and Dissertations

Biogeography of the Himalayan region [to include the Qinghai-Tibetan Plateau (QTP)] evolved over a ~30M year span, catalyzed by the collision of the Indian and Eurasian plates. The resulting uplift produced major ecological and climatic effects, that in turn drove the diversification of biodiversity. As a result, the QTP is designated as a global biodiversity hotspot particularly vulnerable to cumulative climatic effects, including shrinking distributions, declining numbers, and local extinctions. Understanding how the biodiversity within the Himalaya/ QTP was established and maintained is a necessary first step in prioritizing conservation efforts.

Fishes in global montane regions, such as the Himalaya, …

Assessment Of Genetic Diversity In Largetooth Sawfish, Pristis Pristis, Populations Over The 20th Century, Ann Fearing

Master's Theses

The Critically Endangered Largetooth Sawfish, Pristis pristis, experienced global declines in range and abundance over the past century and Australia is now their last stronghold. This research aimed to understand whether these declines have been accompanied by a reduction in levels of genetic diversity. Using P. pristis tissue samples sourced from natural history specimens, three fragments (616-bp, 386-bp, 141-bp) in the mitochondrial DNA (mtDNA) control region were PCR-amplified. At each fragment, significant genetic structure was found in P. pristis overall (Φ_ST=0.946, N=9; 0.813, N=54; 0.771, N=99). The Indo-West Pacific and Atlantic/Eastern Pacific each harbor genetically distinct lineages of …

Evaluation Of The Xpert Carba-R Nxg Assay For Detection Of Carbapenemase Genes In A Global Challenge Set Of Pseudomonas Aeruginosa Isolates, Fred C. Tenover, Christian M. Gill, Tomefa E. Asempa, Isabella A. Tickler, Caitlin M. Dela Cruz, David P. Nicolau

Biology Faculty Publications

The growing prevalence and diversity of carbapenemase producers among carbapenem-resistant Pseudomonas aeruginosa (CRPA) isolates warrants an expansion of detection capabilities. The purpose of this study was to evaluate the performance of the commercially available Xpert Carba-R (Carba-R) and the research-use-only Xpert Carba-R NxG (Carba-R NxG) in a global collection of P. aeruginosa. The challenge set included 123 P. aeruginosa clinical isolates from 12 countries. Isolates were previously categorized via PCR or whole-genome sequencing. Carbapenemase classes tested include VIM, IMP, NDM, SPM, KPC, and GES. Non-carbapenemase (non-CP)-harboring isolates were also tested (negative control). Isolates were tested using the Carba-R NxG and …

Quantifying Structure And Variation In Complex Phylogenetic Data, Genevieve Geraldine Mount

LSU Doctoral Dissertations

Identifying the source and structure of variation in nature is crucial to understanding fundamental aspects of evolution. Despite a recent plethora of genetic and morphological data, many interesting questions about the relationships between different groups remain unresolved. My dissertation evaluates three approaches for identifying and quantifying the variation within phylogenetic datasets. Characterizing variation within datasets and across analytical methods gives insight into biologically interesting characters, unusual evolutionary processes, and areas for model improvement.

Network-based community detection approaches offer a powerful tool to describe variation in phylogenetic signal across the genome (i.e., gene tree variation). In Chapter 2, I investigate the …

Spatio-Temporal Dynamics Of Fungal Communities And Their Effects On Plants, Kel Cook

Biology ETDs

Fungi perform several critical functions in the environment. Spatiotemporal distributions of fungal communities will mediate when and where these functions happen and how they vary across the landscape. I first explored tropical tree canopy fungal community variation at small spatial scales and documented near total turnover of fungi across sub-meter distances and among adjacent substrates. The second chapter analyzed fungal turnover over the course of three years, where community stability was driven primarily by abundant fungi. In the third chapter, I tested effects of the environment, including host plant and habitat, on canopy fungal communities and found only small effects, …

Identification Of Novel Host Genes Required For Antiviral Immunity And Viral Genome Replication In C. Elegans, Fei Meng

LSU Doctoral Dissertations

RNA interference (RNAi) is a wide-spread gene silencing mechanism that control diverse biological functions and triggered by small interfering RNAs (siRNAs) processed from the viral genome or its replication intermediates. Mechanistic studies of antiviral RNAi in Caenorhabditis elegans has led to the identification of several critical factors involved in the process. As a result, whether antiviral RNAi requires additional novel genes remains to be an open question.

Viruses are intracellular parasites that rely on host products for reproduction. Disrupting their interaction with host factors can significantly compromise their replication and keep them under control. Thus, identification of host genes …

The Nature Of Genes Expressed Differently After Environmental Drug Exposure, Nicci Siffel

Scholars Week

The Nature of Genes Expressed Differently after Environmental Drug Exposure

N. Siffel, S. Anderson, B. Subedi, D.R. Hammond-Weinberger

Drug use, of prescription or illicit varieties, alter bodily functions in different ways, especially in the nervous system. These drugs are found in sources of drinking water because they are not removed by wastewater treatment facilities. To investigate the effects of these drugs as they appear in mixtures, we exposed groups of zebrafish embryos to cocktails of drugs and screened for genes that were differentially expressed between the experimental and control groups and could thus give more insight into their biological functions. …

Exploring A Novel Substrate-Borne Vibratory Signal In The Wolf Spider Schizocosa Floridana, Malcolm F. Rosenthal, Eileen Hebets, Rowan H. Mcginley, Cody Raiza, James Starrett, Lin Yan, Damian O. Elias

Eileen Hebets Publications

Animals communicate using a diversity of signals produced by a wide array of physical structures. Determining how a signal is produced provides key insights into signal evolution. Here, we examine a complex vibratory mating display produced by male Schizocosa floridana wolf spiders. This display contains three discrete substrate-borne acoustic components (known as “thumps”, “taps”, and “chirps”), each of which is anecdotally associated with the movement of a different body part (the pedipalps, legs, and abdomen respectively). In order to determine the method of production, we employ a combination of high-speed video/audio recordings and SEM imaging of possible sound-producing structures. Previous …

Testing The Hypothesized Antipredator Defence Function Of Stridulation In The Spiny Orb-Weaving Spider, Micrathena Gracilis, Tyler B. Corey, Eileen A. Hebets

Eileen Hebets Publications

The observable diversity of antipredator defenses across organisms demonstrates predation’s impact on trait evolution. The functions of many traits that are presumed to have an antipredator function have never been directly tested. The spiny orb-weaving spider, Micrathena gracilis, for example, stridulates when grasped. While stridulation was first hypothesized to be an antipredator defense nearly 50 years ago, no data exist to support this hypothesis. To explore the form and function of M. gracilis stridulation, we first quantified the behavioral and acoustical properties of sound production. Next, using laboratory assays, we directly tested the effect of stridulation on survival with …

Inheritability Of Ciprofloxacin-Induced Mitochondrial Mutations From Parental To Offspring Generation Using Quantitative Polymerase Chain Reaction, Rose Mccoy

Honors Program: Senior Projects (Public)

In all eukaryotes, mitochondria are known as the powerhouse of the cell (Siekevitz, 1957). In plants, however, their mitochondrial genome is especially strange. Plant mitochondrial genomes are extremely large and contain both linear and circular subgenomic DNA fragments. Plant mitochondrial genomes undergo a significant amount of mutations in the form of rearrangements. However, it is not known how often these rearrangements are inherited by the next generation. It is thought that plant cells that are still dividing have higher rates of DNA repair, such as double-strand break repair, to ensure the quality of that plant lineage. As follows, it is …

Identification And Characterization Of Novel Genes And Genetic Interactions That Influence Iba Metabolism, Vanessica Jawahir

Dissertations

Indole-3-butyric acid (IBA) is an endogenous storage auxin important for maintaining appropriate indole-3-acetic acid (IAA) levels that influences primary root elongation and lateral root development. IBA is metabolized into free IAA in the peroxisome in a multistep process similar to fatty acid β-oxidation. Although many components specific to IBA metabolism and peroxisome function have been identified, our understanding is incomplete. I sought to identify novel components of IBA metabolism or peroxisome function by conducting a forward genetic screen for Arabidopsis thaliana plants with enhanced resistance to IBA. I identified Long chain acyl-CoA synthetase 4 (LACS4) as a novel gene functioning …

Herb-Layer Dynamics In An Old-Growth Forest: Vegetation–Environment Relationships And Response To Invasion-Related Perturbations, Taylor M. Buskey, Margaret E. Maloney, Julia I. Chapman, Ryan W. Mcewan

Biology Faculty Publications

Temperate forests of eastern North America are subject to multiple invasions from non-native species that have the potential to drive long-term dynamics in biodiversity. Garlic mustard (Alliaria petiolata (M. Bieb.) Cavara and Grande) is an invasive plant in many deciduous forests, and management efforts often focus on removing this species to initiate native species restoration. Agrilus planipennis Fairmaire (emerald ash borer; Coleoptera: Buprestidae) is a non-native insect pest that has caused substantial loss of ash trees (Fraxinus spp. L.) in North America. Our goal was to understand how the herbaceous layer in an old-growth forest responded to the removal of …

Mechanistic Insights Into Strigolactone Biosynthesis, Signaling And Regulation During Plant Growth And Development, Kaiser Iqbal Wani, Andleeb Zehra, Sadaf Choudhary, M Naeem, M. Masroor A. Khan, Christian Danve Castroverde, Tariq Aftab

Biology Faculty Publications

Strigolactones (SLs) constitute a group of carotenoid-derived phytohormones with butenolide moieties. These hormones are involved in various functions, including regulation of secondary growth, shoot branching and hypocotyl elongation, and stimulation of seed germination. SLs also control hyphal branching of arbuscular mycorrhizal (AM) fungi, and mediate responses to both abiotic and biotic cues. Most of these functions stem from the interplay of SLs with other hormones, enabling plants to appropriately respond to changing environmental conditions. This dynamic interplay provides opportunities for phytohormones to modulate and augment one another. In this article, we review our current mechanistic understanding of SL biosynthesis, receptors …

A Summary Of Current Research Into Neurodegenerative Disorders Using Drosophila Melanogaster, Chase Cortese

Honors Theses

Neurodegenerative disorders such as Alzheimer’s disease are characterized by damage to neural cells causing widespread neurological deficits. Historically, these diseases were deemed as inevitable declines in cognitive and neurological function that occurred with aging. Recent research has revealed, however, that these diseases have molecular bases allowing potential clinical intervention. The groundbreaking discoveries have been made using differing model organisms, which can replicate the phenotype and physiological cause of these disorders. One major model organism that has been used is the fruit fly, Drosophila melanogaster. They have served various roles in elucidating gene pathways and neurophysiological bases seen in these diseases. …

Versatile Phenotype-Activated Cell Sorting, Jihwan Lee, Zhuohe Liu, Peter H Suzuki, John F Ahrens, Shujuan Lai, Xiaoyu Lu, Sihui Guan, François St-Pierre

Faculty, Staff and Students Publications

Unraveling the genetic and epigenetic determinants of phenotypes is critical for understanding and re-engineering biology and would benefit from improved methods to separate cells based on phenotypes. Here, we report SPOTlight, a versatile high-throughput technique to isolate individual yeast or human cells with unique spatiotemporal profiles from heterogeneous populations. SPOTlight relies on imaging visual phenotypes by microscopy, precise optical tagging of single target cells, and retrieval of tagged cells by fluorescence-activated cell sorting. To illustrate SPOTlight's ability to screen cells based on temporal properties, we chose to develop a photostable yellow fluorescent protein for extended imaging experiments. We screened 3 …

Does The Presence Of Multiple Β-Lactamases In Gram-Negative Bacilli Impact The Results Of Antimicrobial Susceptibility Tests And Extended-Spectrum Β-Lactamase And Carbapenemase Confirmation Methods?, Fred C. Tenover, Caitlin M. Dela Cruz, Scott Dewell, Victoria M. Le, Isabella A. Tickler

Biology Faculty Publications

Objectives: Many multidrug-resistant Gram-negative bacilli (MDR-GNB) harbour multiple β-lactamases. The aim of this study was to assess the impact of multiple β-lactamase carriage on the accuracy of susceptibility tests and extended-spectrum β-lactamase (ESBL) and carbapenemase confirmation methods.

Methods: A total of 50 MDR-GNB, of which 29 carried multiple β-lactamases, underwent broth microdilution (BMD) and disk diffusion (DD) testing as well as confirmation tests for ESBLs and carbapenemases. Whole-genome sequencing (WGS) was used for β-lactamase gene identification.

Results: Categorical agreement of BMD and DD testing results ranged from 86.5 to 97.7% for 10 β-lactam agents. BMD and DD algorithms for ESBL …

Analyses Of The Expression, Immunohistochemical Properties And Serodiagnostic Potential Of Schistosoma Japonicum Peroxiredoxin-4, Minh-Anh Dang-Trinh, Jose Ma. M. Angeles, Kharleezelle J. Moendeg, Adrian Miki C. Macalanda, Thu-Thuy Nguyen, Luna Higuchi, Shotaro Nakagun, Masahi Kirinoki, Yuichi Chigusa, Yasuyuki Goto, Shin-Ichiro Kawazu

Biology Faculty Publications

Background

Schistosoma japonicum, which inhabits the mesenteric vein of the mammalian hosts for about 20 to 30 years, is subjected to the oxidative stresses from the host defense mechanism during their intra-mammalian stages. To counteract this host immune attack, the parasite utilizes their antioxidant system for survival inside the host. Peroxiredoxins (Prxs), thiol-specific antioxidant proteins, play an essential role for protecting the parasite against oxidative stress by reducing hydrogen peroxide to water. Only three types of 2-Cys Prxs have been previously characterized in S. japonicum whereas a fourth Prx has been identified for Schistosoma mansoni as Prx-4. A sequence …

Employing High Probability Gene Choice Elements To Understand Singular Odorant Receptor Expression, Raena Mina

Dissertations, Theses, and Capstone Projects

The ability to detect odorous chemicals in the environment is the oldest of the senses necessary for survival, from escaping danger, finding mates, to locating food. It is said that humans can identify and discriminate up to a trillion different odor mixtures. For chemoreception to have such a high discriminatory power, would require a diverse population of cells dedicated for odor detection. These detector cells are the olfactory sensory neurons (OSNs), which express odorant receptors (ORs) that bind to chemical odors in the environment. In order to increase specificity and sensitivity, an essential property in olfaction is for each OSN …

The Influence Of Riparian Invasion By The Terrestrial Shrub Lonicera Maackii On Aquatic Macroinvertebrates In Temperate Forest Headwater Streams, Michelle N. Little, Kevin W. Custer, Eric B. Borth, Julia I. Chapman, Mitchell J. Kukla, Corey Kuminecz, Margaret E. Maloney, Michaela J. Woods, Ryan Mcewan

Biology Faculty Publications

The ecology of headwater streams is tightly linked to the riparian zone through organic matter subsidies which are highly susceptible to alteration due to biological invasion. Lonicera maackii is a non-native shrub that is a highly successful invader of headwater stream riparian zones in the American Midwest. We assessed effects on benthic macroinvertebrates across a gradient of invasion intensity from references sites with minimal invasion to a site that had a very heavy invasion. Benthic macroinvertebrates were sampled throughout the year and compositional differences were assessed using Non-metric Multidimensional Scaling ordination, and by comparing the prevalence of sensitive (Ephemeroptera, Plectoptera, …

Structure And Evolution Of Lizard Immunity Genes, Trent Santonastaso

LSU New Orleans Theses and Dissertations

One of the most important gene families to play a role in adaptive immunity is the major histocompatibility complex (MHC). MHC class II loci are considered to be the most variable loci in the vertebrate genome, and studies have shown that this variability can be maintained through complex co-evolutionary dynamics between host and parasite. Despite the rich body of research into the MHC, there is comparatively little understanding of its genomic architecture in reptiles. Similarly, loci associated with innate immunity have received little attention in reptiles compared to other vertebrates. In the first chapter, we investigated the structure and organization …

Identifying Positive Selection In Multiple Subspecies Of Xylella Fastidiosa, Daniel Doroteo Flores

Theses and Dissertations

For this study, we will be looking to identify positive selection in eight genomes of the bacterial plant pathogen Xylella fastidiosa. A previous study used a branching method that identified 2 genes with positive selection along with a site-specific method identifying 34 genes showing positive selection. This current study focused specifically on the site-specific method, resulting in 28 genes (of 1,039 tested) showing positive selection. Of the 28 genes showing positive selection, 12 of them come from the pathogenicity, virulence and cellular structural categories. The remaining genes are found in the biosynthesis, metabolism, macro metabolism, and cellular process categories. …

Model-Based Analysis Of Chromatin Interactions From Dcas9-Based Capture-3c-Seq., Yong Chen, Yunfei Wang, Xin Liu, Jian Xu, Michael Q Zhang

College of Science & Mathematics Departmental Research

Deciphering long-range chromatin interactions is critical for understanding temporal and tissue-specific gene expression regulated by cis- and trans-acting factors. By combining the chromosome conformation capture (3C) and biotinylated dCas9 system, we previously established a method CAPTURE-3C-seq to unbiasedly identify high-resolution and locus-specific long-range DNA interactions. Here we present the statistical model and a flexible pipeline, C3S, for analysing CAPTURE-3C-seq or similar experimental data from raw sequencing reads to significantly interacting chromatin loci. C3S provides all steps for data processing, quality control and result illustration. It can automatically define the bin size based on the binding peak of the dCas9-targeted regions. …

Arabidopsis Heat Shock Granules Exhibit Dynamic Cellular Behavior And Can Form In Response To Protein Misfolding In The Absence Of Elevated Temperatures, Rosalie Lawrence , '12, Nicholas J. Kaplinsky

Biology Faculty Works

No abstract provided.

Wild Mice With Different Social Network Sizes Vary In Brain Gene Expression, Patricia C. Lopes, Barbara König

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Background

Appropriate social interactions influence animal fitness by impacting several processes, such as mating, territory defense, and offspring care. Many studies shedding light on the neurobiological underpinnings of social behavior have focused on nonapeptides (vasopressin, oxytocin, and homologues) and on sexual or parent-offspring interactions. Furthermore, animals have been studied under artificial laboratory conditions, where the consequences of behavioral responses may not be as critical as when expressed under natural environments, therefore obscuring certain physiological responses. We used automated recording of social interactions of wild house mice outside of the breeding season to detect individuals at both tails of a distribution …

Characterization Of The Overexpression Of The Native H+-Pumping Pyrophosphatase In The Microalga Picochlorum Soloecismus, Kimberly T. Wright

Biology ETDs

Microalgae are of interest for the creation of sustainable and cost competitive alternatives to petroleum-based fuels and chemicals. However, cultivation, extraction and processing of algal biomass requires improved yields to achieve economic feasibility. The advancement of microalgal biotechnology and various genetic engineering techniques allow the improvement of microalgae biomass for this purpose. Here, the characterization of the overexpression of the native vacuolar H+ pumping pyrophosphate (AVP1) in Picochlorum soloecismus was examined. AVP1 overexpression causes biomass increase in relevant plant crops. When overexpressed in this microalga it increases carbon storage in the form of starch in a closed laboratory photobioreactor. However, …

Inactivation Of Hippo And Cjun-N-Terminal Kinase (Jnk) Signaling Mitigate Fus Mediated Neurodegeneration In-Vivo, Ankita Sarkar, Abijeet Singh Mehta, Prajakta Deshpande, Madhuri Kango-Singh, Udai Bhan Pandey, Amit Singh

Biology Faculty Publications

Amyotrophic Lateral Sclerosis (ALS), a late-onset neurodegenerative disorder characterized by the loss of motor neurons in the central nervous system, has no known cure to-date. Disease causing mutations in human Fused in Sarcoma (FUS) leads to aggressive and juvenile onset of ALS. FUS is a well-conserved protein across different species, which plays a crucial role in regulating different aspects of RNA metabolism. Targeted misexpression of FUS in Drosophila model recapitulates several interesting phenotypes relevant to ALS including cytoplasmic mislocalization, defects at the neuromuscular junction and motor dysfunction. We screened for the genetic modifiers of human FUS-mediated neurodegenerative phenotype using molecularly …

Aav-Crispr Gene Editing Is Negated By Pre-Existing Immunity To Cas9, Ang Li, Mark R Tanner, Ciaran M Lee, Ayrea E Hurley, Marco De Giorgi, Kelsey E Jarrett, Timothy H Davis, Alexandria M Doerfler, Gang Bao, Christine Beeton, William R Lagor

Faculty, Staff and Students Publications

Adeno-associated viral (AAV) vectors are a leading candidate for the delivery of CRISPR-Cas9 for therapeutic genome editing in vivo. However, AAV-based delivery involves persistent expression of the Cas9 nuclease, a bacterial protein. Recent studies indicate a high prevalence of neutralizing antibodies and T cells specific to the commonly used Cas9 orthologs from Streptococcus pyogenes (SpCas9) and Staphylococcus aureus (SaCas9) in humans. We tested in a mouse model whether pre-existing immunity to SaCas9 would pose a barrier to liver genome editing with AAV packaging CRISPR-Cas9. Although efficient genome editing occurred in mouse liver with pre-existing SaCas9 immunity, this was accompanied by …

Elucidating The Role Of Apl-1, The C. Elegans Ortholog Of The Human Amyloid Precursor Protein, Adanna G. Alexander

Dissertations, Theses, and Capstone Projects

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder, impacting approximately 6 million Americans. AD is the leading cause of dementia amongst the aged population. Post mortem analysis of the brains of AD patients shows high quantities of extracellular Aβ peptide deposits, which are derived from cleavage of the amyloid precursor protein (APP). Mutations in APP and proteins responsible for APP cleavage, PSENs, greatly increase the incidence of developing AD at an early age. Despite its strong correlation to the progression of AD, the role of APP remains unclear.

Here we investigate the role of the Caenorhabditis elegans ortholog, APL-1. We …

Molecular Roles Of Small Inner Membrane Proteins In Escherichia Coli Cell Envelope Integrity, Aaron Mychack

Dissertations, Theses, and Capstone Projects

The biological membrane is an essential, defining feature of all cells. Biological membranes comprise phospholipid bilayers as well as a complement of proteins which are unique to a given organism. These proteins play a central role in dictating the biochemical state of the cell’s internal cytoplasm by controlling selective passage of solutes in and out of the cell, transducing signals in response to extracellular stimuli, and controlling the biogenesis of the bilayer itself which is critical towards barrier function. For most bacteria, the periphery of the cell is multi-layered, including both a biological membrane as well as a peptidoglycan cell …