Computational Biology Commons^™

Model-Based Deep Autoencoders For Clustering Single-Cell Rna Sequencing Data With Side Information, Xiang Lin

Dissertations

Clustering analysis has been conducted extensively in single-cell RNA sequencing (scRNA-seq) studies. scRNA-seq can profile tens of thousands of genes' activities within a single cell. Thousands or tens of thousands of cells can be captured simultaneously in a typical scRNA-seq experiment. Biologists would like to cluster these cells for exploring and elucidating cell types or subtypes. Numerous methods have been designed for clustering scRNA-seq data. Yet, single-cell technologies develop so fast in the past few years that those existing methods do not catch up with these rapid changes and fail to fully fulfil their potential. For instance, besides profiling transcription …

Dna Methylation-Based Epigenetic Biomarkers In Cell-Type Deconvolution And Tumor Tissue Of Origin Identification, Ze Zhang

Dartmouth College Ph.D Dissertations

DNA methylation is an epigenetic modification that regulates gene expression and is essential to establishing and preserving cellular identity. Genome-wide DNA methylation arrays provide a standardized and cost-effective approach to measuring DNA methylation. When combined with a cell-type reference library, DNA methylation measures allow the assessment of underlying cell-type proportions in heterogeneous mixtures. This approach, known as DNA methylation deconvolution or methylation cytometry, offers a standardized and cost-effective method for evaluating cell-type proportions. While this approach has succeeded in discerning cell types in various human tissues like blood, brain, tumors, skin, breast, and buccal swabs, the existing methods have major …

Investigating The Impact Of Transcription On Mutation Rates, Sarah Patterson

Theses and Dissertations

tRNA genes are highly transcribed and perform one of the most fundamental cellular functions. Although a universal pattern observed across all three domains of life is that highly transcribed genes tend to evolve slowly, tRNA genes have been shown previously to evolve rapidly. This rapid sequence evolution could result from relaxed selection, increased mutation rate, or a combination of both. Here, we use mutation-accumulation line sequencing data to show that tRNA genes accumulate more mutations than other gene types. Our results indicate that this elevated mutation rate is a consequence of both elevated transcription-associated mutagenesis and a lack of transcription-coupled …

Increased Coding Potential Of Bovine Herpesvirus 1, Victoria Jefferson

Theses and Dissertations

Bovine respiratory disease (BRD) costs the cattle industry millions of dollars in costs in treatment and loss every year in the United States. A significant pathogen often contributes to BRD is Bovine Herpesvirus 1 (BoHV-1), a double stranded DNA virus with the ability to establish latency in the trigeminal ganglia and neurons. Primary infection with BoHV-1 results in immunosuppression that increases the risk of secondary bacterial infection and pneumonia. Because herpesviruses infect their hosts for life and can be reactivated in times of stress, BoHV-1 can present a recurring risk of BRD. The following research aims to expand the knowledge …

Analyzing Extracellular Vesicles For Disease Monitoring In Metastatic Colorectal Cancer Patients, Vahid Bahrambeigi

Dissertations and Theses (Open Access)

Colorectal cancer (CRC) is the second leading cause of cancer deaths in the United States. Metastases are the main cause of cancer-related death, and the most frequent metastatic sites in patients with CRCs are liver and lung. To confirm the diagnosis of metastatic CRC (mCRCs) and to classify mCRCs, tumor biopsy of a suspected metastasis is often required. The consensus molecular subtype (CMS) classification which is based on gene expression profiles of CRC tumor specimens, is a predictive factor for treatment outcomes of standard chemotherapies for mCRCs. The practicality of repeated tumor biopsies for disease monitoring in mCRC patients is …

The Typical Trna Co-Expresses Multiple 5' Trna Halves Whose Sequences And Abundances Depend On Isodecoder And Isoacceptor And Change With Tissue Type, Cell Type, And Disease, Robert Akins, Kayleigh Ostberg, Tess Cherlin, Nikolas Tsiouplis, Phillipe Loher, Isidore Rigoutsos

Computational Medicine Center Faculty Papers

Transfer RNA-derived fragments (tRFs) are noncoding RNAs that arise from either mature transfer RNAs (tRNAs) or their precursors. One important category of tRFs comprises the tRNA halves, which are generated through cleavage at the anticodon. A given tRNA typically gives rise to several co-expressed 5'-tRNA halves (5'-tRHs) that differ in the location of their 3' ends. These 5'-tRHs, even though distinct, have traditionally been treated as indistinguishable from one another due to their near-identical sequences and lengths. We focused on co-expressed 5'-tRHs that arise from the same tRNA and systematically examined their exact sequences and abundances across 10 different human …

The Detection Of Putative Recessive Lethal Haplotypes In Irish Sheep Populations, Rory Mcauley

ORBioM (Open Research BioSciences Meeting)

In livestock populations, recessive lethal alleles are a known contributor to poor reproductive performance due to embryonic death in homozygous individuals. Despite their lethal effect in the recessive form, these alleles may be maintained at high frequencies among carrier animals because of their positive pleiotropic effects on economically important traits. Although several such recessive alleles have been identified in cattle and pig populations, limited studies have been completed in sheep, and none within Irish sheep populations. Genotype data for 69,034 animals from five major Irish sheep breeds genotyped on a variety of panels was available for this study. Only animals …

Tracing Evolution Of Gene Transfer Agents Using Comparative Genomics, Roman Kogay

Dartmouth College Ph.D Dissertations

The accumulating evidence suggest that viruses and their components can be domesticated by their hosts, equipping them with convenient molecular toolkits for various functions. One of such domesticated system is Gene Transfer Agents (GTAs) that are produced by some bacteria and archaea. GTAs morphologically resemble small phage-like particles and contain random fragments of their host genome. They are produced only by a small fraction of the microbial population and are released through a lysis of the host cell. Bioinformatic analyses suggest that GTAs are especially abundant in the taxonomic class of Alphaproteobacteria, where they are vertically inherited and evolve …

Convolutional Neural Network-Based Gene Prediction Using Buffalograss As A Model System, Michael Morikone

Complex Biosystems Program: Dissertations and Student Research

The task of gene prediction has been largely stagnant in algorithmic improvements compared to when algorithms were first developed for predicting genes thirty years ago. Rather than iteratively improving the underlying algorithms in gene prediction tools by utilizing better performing models, most current approaches update existing tools through incorporating increasing amounts of extrinsic data to improve gene prediction performance. The traditional method of predicting genes is done using Hidden Markov Models (HMMs). These HMMs are constrained by having strict assumptions made about the independence of genes that do not always hold true. To address this, a Convolutional Neural Network (CNN) …

The Role Of Non-Coding Rnas In Myelodysplastic Neoplasms, Vasileios Georgoulis, Epameinondas Koumpis, Eleftheria Hatzimichael

Computational Medicine Center Faculty Papers

Myelodysplastic syndromes or neoplasms (MDS) are a heterogeneous group of myeloid clonal disorders characterized by peripheral blood cytopenias, blood and marrow cell dysplasia, and increased risk of evolution to acute myeloid leukemia (AML). Non-coding RNAs, especially microRNAs and long non-coding RNAs, serve as regulators of normal and malignant hematopoiesis and have been implicated in carcinogenesis. This review presents a comprehensive summary of the biology and role of non-coding RNAs, including the less studied circRNA, siRNA, piRNA, and snoRNA as potential prognostic and/or predictive biomarkers or therapeutic targets in MDS.

Modeling Nonsegmented Negative-Strand Rna Virus (Nnsv) Transcription With Ejective Polymerase Collisions And Biased Diffusion, Felipe-Andres Piedra

Research Symposium

Background: The textbook model of NNSV transcription predicts a gene expression gradient. However, multiple studies show non-gradient gene expression patterns or data inconsistent with a simple gradient. Regarding the latter, several studies show a dramatic decrease in gene expression over the last two genes of the respiratory syncytial virus (RSV) genome (a highly studied NNSV). The textbook model cannot explain these phenomena.

Methods: Computational models of RSV and vesicular stomatitis virus (VSV – another highly studied NNSV) transcription were written in the Python programming language using the Scientific Python Development Environment. The model code is freely available on GitHub: …

An Implementation Of The Method Of Moments On Chemical Systems With Constant And Time-Dependent Rates, Emmanuel O. Adara, Roger B. Sidje

Northeast Journal of Complex Systems (NEJCS)

Among numerical techniques used to facilitate the analysis of biochemical reactions, we can use the method of moments to directly approximate statistics such as the mean numbers of molecules. The method is computationally viable in time and memory, compared to solving the chemical master equation (CME) which is notoriously expensive. In this study, we apply the method of moments to a chemical system with a constant rate representing a vascular endothelial growth factor (VEGF) model, as well as another system with time-dependent propensities representing the susceptible, infected, and recovered (SIR) model with periodic contact rate. We assess the accuracy of …

Genome-Scale Methylation Analysis In Blood And Tumor Identifies Immune Profile, Age Acceleration, And Dna Methylation Alterations Associated With Bladder Cancer Outcomes, Ji-Qing Chen

Dartmouth College Ph.D Dissertations

Bladder cancer patients receive frequent screening due to the high tumor recurrence rate (more than 60%). Nowadays, the conventional monitoring method relies on cystoscopy which is highly invasive and increases patient morbidity and burden to the health care system with frequent follow-up. As a result, it is urgent to explore novel markers related to the outcomes of bladder cancer. Immune profiles have been associated with cancer outcomes and may have the potential to be biomarkers for outcomes management. However, little work has been conducted to investigate the associations of immune cell profiles with bladder cancer outcomes. Here, I utilized the …

Computational Analysis Of Antibody Binding Mechanisms To The Omicron Rbd Of Sars-Cov-2 Spike Protein: Identification Of Epitopes And Hotspots For Developing Effective Therapeutic Strategies, Mohammed Alshahrani

Computational and Data Sciences (PhD) Dissertations

The advent of the Omicron strain of SARS-CoV-2 has elicited apprehension regarding its potential influence on the effectiveness of current vaccines and antibody treatments. The present investigation involved the implementation of mutational scanning analyses to examine the impact of Omicron mutations on the binding affinity of four categories of antibodies that target the Omicron receptor binding domain (RBD) of the Spike protein. The study demonstrates that the Omicron variant harbors 23 unique mutations across the RBD regions I, II, III, and IV. Of these mutations, seven are shared between RBD regions I and II, while three are shared among RBD …

Landscape Of Ecdna-Borne Non-Coding Rnas In Glioblastoma, Dexin Yang

Dissertations and Theses (Open Access)

Recent advances in cancer genetics found that strong oncogene transcription can occur on a form of non-chromosome DNAs that is often amplified to tens or hundreds of copies, and that can exist in more than half of cancer types. This type of genetic material was termed extrachromosomal DNA (ecDNA). ecDNA appears to be epigenetically highly accessible and transcriptionally active compared with chromosomal DNA, which may partially underlie their critical roles in driving oncogene overexpression and cancer evolution. However, the full molecular mechanisms and regulators that confer the exceptional transcriptional activity of ecDNA-associated genes are incompletely understood.

Enhancers are key genetic …

Missing Value Imputation For Single Omics And Multi-Omics Data, Meng Song

Dissertations

The integration analyses of multi-omics data have the advantages of extending our understanding of biological system across multiple omics layers, unraveling the functional mechanism of complex disease development, and refining the discovery of novel drug targets. However, multi-omics studies often face challenges such as data heterogeneity, missing values problem, interpretability, and imbalance classes. Among these challenges, the missing values problem is a critical issue for large cohort studies as not all samples will get a complete measurement for all the omics layers. To address the problem of missing values in multi-omics data, I focused on the imputation of completely missing …

Annotation Of Non-Model Species’ Genomes, Taiya Jarva

Master's Theses

The innovations in high throughput sequencing technologies in recent decades has allowed unprecedented examination and characterization of the genetic make-up of both model and non-model species, which has led to a surge in the use of genomics in fields which were previously considered unfeasible. These advances have greatly expanded the realm of possibilities in the fields of ecology and conservation. It is now possible to the identification of large cohorts of genetic markers, including single nucleotide polymorphisms (SNPs) and larger structural variants, as well as signatures of selection and local adaptation. Markers can be used to identify species, define population …

Structural Diversity And Stress Regulation Of The Plant Immunity-Associated Calmodulin-Binding Protein 60 (Cbp60) Family Of Transcription Factors In Solanum Lycopersicum (Tomato), Vanessa Shivnauth, Sonya Pretheepkumar, Eric J. R. Marchetta, Christina A. M. Rossi, Keaun Amani, Christian Castroverde

Biology Faculty Publications

Cellular signaling generates calcium (Ca2+) ions, which are ubiquitous secondary messengers decoded by calcium-dependent protein kinases, calcineurins, calreticulin, calmodulins (CAMs), and CAM-binding proteins. Previous studies in the model plant Arabidopsis thaliana have shown the critical roles of the CAM-BINDING PROTEIN 60 (CBP60) protein family in plant growth, stress responses, and immunity. Certain CBP60 factors can regulate plant immune responses, like pattern-triggered immunity, effector-triggered immunity, and synthesis of major plant immune-activating metabolites salicylic acid (SA) and N-hydroxypipecolic acid (NHP). Although homologous CBP60 sequences have been identified in the plant kingdom, their function and regulation in most species remain unclear. In …

Exploring The Interactions Between Sars-Cov-2 And Host Proteins, Sojan Shrestha

School of Biological Sciences: Dissertations, Theses, and Student Research

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the current pandemic, Coronavirus Disease 2019 (COVID-19). SARS-CoV-2 is considered to be of zoonotic origin; it originated in non-human animals and was transmitted to humans. Since the early stage of the pandemic, however, the evidence of transmissions from humans to animals (reverse zoonoses) has been found in multiple animal species including mink, white-tailed deer, and pet and zoo animals. Furthermore, secondary zoonotic events of SARS-CoV-2, transmissions from animals to humans, have been also reported. It is suggested that non-human hosts can act as SARS-CoV-2 reservoirs where accumulated …

Atomistic Assessment Of Drug-Phospholipid Interactions Consequent To Cancer Treatment: A Study Of Anthracycline Cardiotoxicity, Yara Elsayed Ahmed

Theses and Dissertations

Despite being one of the most effective chemotherapeutic agents developed to date, Anthracyclines are notorious for their cardiotoxicity. Their clinical use is frequently limited both in dosage and in prescription due to the severe cardiac damage they cause. The mechanism of anthracycline-induced cardiotoxicity is not yet fully understood. However, it is hypothesized that interactions with the myocardial membrane play an important role in imparting cardiotoxicity. In this study, we use molecular dynamics simulations and density functional theory calculations to study the anthracycline drug molecules and the interactions that they have with the myocardial membrane. We construct a myocardial membrane model …

Machine Learning And Network Embedding Methods For Gene Co-Expression Networks, Niloofar Aghaieabiane

Dissertations

High-throughput technologies such as DNA microarrays and RNA-seq are used to measure the expression levels of large numbers of genes simultaneously. To support the extraction of biological knowledge, individual gene expression levels are transformed into Gene Co-expression Networks (GCNs). GCNs are analyzed to discover gene modules. GCN construction and analysis is a well-studied topic, for nearly two decades. While new types of sequencing and the corresponding data are now available, the software package WGCNA and its most recent variants are still widely used, contributing to biological discovery.

The discovery of biologically significant modules of genes from raw expression data is …

Evolution And Epidemiology Of Channel Catfish Virus (Ccv), Arun Venugopalan

Theses and Dissertations

Channel catfish virus disease (CCVD) is the principal viral disease in the United States catfish industry. The CCVD is caused by channel catfish virus (CCV), with mortality reaching up to 100% in fingerlings. CCV is assigned taxonomically to the family Alloherpesviridae, genus Ictalurivirus, species Ictalurid herpesvirus 1 (IcHV-1). To date, virulence, immunogenicity, and genome plasticity of the CCV field isolates have not been investigated. Three genotypes of CCV (IcHV-1A, IcHV-1B, and BCAHV) were identified using restriction fragment length polymorphism (RFLP) analysis. Virulence assessment of three representative isolates of RFLP groups suggests that IcHV-1B (pooled survival [mean ± SE]: 58.3% ± …

Integrating Omim And Intact Data For The Analysis Of Gene-Phenotype Interactions In Complex Diseases: A Linux-Based Computational Tool For Network Analysis, Devin Keane

All Theses

The field of genetics is constantly evolving. New advances in bioinformatics and computational approaches are leading to exciting new developments in our ability to treat and prevent diseases. Computational genetics provides valuable insights into the complex mechanisms and layers of biological communication that shape an organism's phenotype. Understanding these mechanisms is critical to advancing human health.

The study of diseases in genetics requires a comprehensive understanding of the interactions between various biological processes, including gene expression, protein synthesis, RNA, metabolism, and cell-cell communication. To effectively address the root causes of such diseases, multi-disciplinary approaches that integrate information from different levels …

Pirna Expression In The Tube Feet Of Lytechinus Variegatus, Reagan Milliet

Honors Theses

Tissue regeneration is an area of research with implications for medicine and animal health. While nearly all living multi-cellular organisms are capable of regeneration, there are major differences in the animal kingdom. Some organisms are capable of regenerating virtually every cell in their bodies. In hopes of engineering tissue regeneration for medical applications, the mechanisms by which organisms regenerate are being widely investigated. To better understand regeneration, the role of P-element Induced WImpy testis (PIWI) proteins are being evaluated. In collaboration with PIWIinteracting RNAs (piRNAs), PIWI proteins have been proven instrumental to transposon silencing and maintenance of the genome in …

Pirna Expression In Regenerative Tissue Of Octopus Bimaculoides, Bailey Ervin

Honors Theses

Tissue regeneration is present in varying capacities across the animal kingdom. Animals such as Hydra and planarians have the capacity to regenerate entire bodies from extremely small sections of amputated tissue. Others, such as humans, have restricted capacities of regeneration, especially in terms of full appendages and specialized tissues such as cardiac and nervous tissue. One of the primary goals of studying regeneration in other organisms is to achieve the development of regenerative medicine. Interaction of P-element induced WImpy testis (PIWI) proteins and PIWI-interacting RNAs (piRNAs) have been implicated in germline genome maintenance, as well as transposable element silencing. Research …

Unique Transcriptional Profiles Underlie Osteosarcomagenesis Driven By Different P53 Mutants, Dhruv Chachad

Dissertations and Theses (Open Access)

Missense mutations in the DNA binding domain of the Trp53 gene are characterized as structural (p53R172H) or contact (p53R245W) mutations based on their effect on the conformation of the protein. These mutations show gain-of-function activities such as increased metastatic incidence as compared to p53 loss, often mediated by their interaction with a repertoire of transcription factors. These interactions are largely context specific. In order to understand the mechanisms by which these mutations drive osteosarcoma progression, we created a mouse model, wherein either the p53 structural mutant p53R172H, or the contact mutant, p53R245W, are expressed specifically in …

Clustering And Analysis Of G Quadruplex Sequences., Aryan Neupane

Electronic Theses and Dissertations

G quadruplex structures are secondary structures located throughout the genome of various organisms with involvement in regulatory functions in different transcription, translation, genome stability, epigenetic regulation as well as cell division. Even with the diverse acknowledgement of G4 structure in vivo, there are no current search tools for G quadruplexes based on already identified G quadruplexes and identified families across different genomes based on sequence diversity. Construction of families of G4 sequences and identifying their polymorphisms within disease and disorders will lead to a better understanding of their functional roles and will further research into the biophysical modeling of interactions …

Reconstructing Mutational Lineages In Breast Cancer By Multi-Patient-Targeted Single Cell Dna Sequencing, Jake Leighton

Dissertations and Theses (Open Access)

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with high rates of metastasis and recurrence, where TNBC patients have a poor 5-year survival and ~50% are non-responsive to chemotherapy. Aneuploidy is a cancer hallmark that is pervasive in over 90% of breast cancer patients and is indicative of complex genomic rearrangements that are acquired during tumor initiation. Although copy number aberrations have been extensively studied in relation to aneuploidy and TNBC initiation, little is currently known regarding the timing and impact of single nucleotide variants (SNVs) contributing to these early transformative genomic events. Paramount to novel …

Acetate Metabolism In The Fungal Pathogen Cryptococcus Neoformans, Oly Ahmed

All Dissertations

Cryptococcus neoformans is an environmental basidiomycetous fungus with a worldwide distribution and a wide range of habitats. Inhalation of the desiccated yeasts or spores of C. neoformans often leads to opportunistic pulmonary infections in immunocompromised individuals, and in severe cases causes lethal meningitis following hematogenous dissemination. During infection, depending on the tissue and disease state, the invading fungi experience a range of nutrient microenvironments within the host body. As a result, rapid metabolic adaptations geared towards efficient utilization of carbon sources alternative to glucose become one of the prime determinants of survival and growth for the pathogen. Incidentally, cryptococcal infection …

Effects Of Cyanobacteria Harmful Algal Blooms On The Microbial Community Within Lake Okeechobee, Fl, Usa, Paisley S. Samuel

All HCAS Student Capstones, Theses, and Dissertations

The Lake Okeechobee (Lake O) watershed is a Floridian freshwater ecosystem that has been affected by the increased frequency and intensity of harmful cyanobacterial bloom (cyanoHAB) events occurring over recent decades. Lake O has several ecological and economic purposes such as providing habitats for various organisms and providing drinking water to urban communities surrounding the lake. Toxic cyanoHAB events are posing a threat to the ecosystem and economy of the lake due to the degradation of water quality. This study investigates how the microbial community structure within Lake O is affected by annual cyanobacterial harmful algal blooms over several years …