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- All Subjects: Genetics
- All Subjects: Genomics
- All Subjects: Green anole--Evolution.
- All Subjects: Sex Chromosomes
- Genre: Academic theses
- Status: Published
Description
In species with highly heteromorphic sex chromosomes, the degradation of one of the sex chromosomes can result in unequal gene expression between the sexes (e.g., between XX females and XY males) and between the sex chromosomes and the autosomes. Dosage compensation is a process whereby genes on the sex chromosomes achieve equal gene expression which prevents deleterious side effects from having too much or too little expression of genes on sex chromsomes. The green anole is part of a group of species that recently underwent an adaptive radiation. The green anole has XX/XY sex determination, but the content of the X chromosome and its evolution have not been described. Given its status as a model species, better understanding the green anole genome could reveal insights into other species. Genomic analyses are crucial for a comprehensive picture of sex chromosome differentiation and dosage compensation, in addition to understanding speciation.
In order to address this, multiple comparative genomics and bioinformatics analyses were conducted to elucidate patterns of evolution in the green anole and across multiple anole species. Comparative genomics analyses were used to infer additional X-linked loci in the green anole, RNAseq data from male and female samples were anayzed to quantify patterns of sex-biased gene expression across the genome, and the extent of dosage compensation on the anole X chromosome was characterized, providing evidence that the sex chromosomes in the green anole are dosage compensated.
In addition, X-linked genes have a lower ratio of nonsynonymous to synonymous substitution rates than the autosomes when compared to other Anolis species, and pairwise rates of evolution in genes across the anole genome were analyzed. To conduct this analysis a new pipeline was created for filtering alignments and performing batch calculations for whole genome coding sequences. This pipeline has been made publicly available.
In order to address this, multiple comparative genomics and bioinformatics analyses were conducted to elucidate patterns of evolution in the green anole and across multiple anole species. Comparative genomics analyses were used to infer additional X-linked loci in the green anole, RNAseq data from male and female samples were anayzed to quantify patterns of sex-biased gene expression across the genome, and the extent of dosage compensation on the anole X chromosome was characterized, providing evidence that the sex chromosomes in the green anole are dosage compensated.
In addition, X-linked genes have a lower ratio of nonsynonymous to synonymous substitution rates than the autosomes when compared to other Anolis species, and pairwise rates of evolution in genes across the anole genome were analyzed. To conduct this analysis a new pipeline was created for filtering alignments and performing batch calculations for whole genome coding sequences. This pipeline has been made publicly available.
ContributorsRupp, Shawn Michael (Author) / Wilson Sayres, Melissa A (Thesis advisor) / Kusumi, Kenro (Committee member) / DeNardo, Dale (Committee member) / Arizona State University (Publisher)
Created2016
Description
Embryonic and juvenile development consist of a series of complex and rapid changes driven by a suite of crucially timed developmental cues within the cell. The developmental process begins at the moment of zygote activation, “jump-started” by maternal factors such as mRNA and proteins until transcription can be zygotically-driven. Regulation of transcription initiation plays a crucial role in this process, as minute changes in the timing, density, and characteristics of gene expression can have drastic effects on the zygote’s development. Specific promoter elements can be linked to different patterns of transcription, driving both ubiquitous and sharply regulated gene expression, thus forming the basis for the time-sensitive developmental processes. In order to better understand the genes expressed during different stages of development and the impact of promoter elements on transcription patterns and transcript concentrations within the cell, I created a Gene Expression and Promoter Atlas in two species within the cryptic species complex, Daphnia pulex. I surveyed five embryonic and two juvenile developmental stages in both a North American and mitochondrially European Daphnia pulex utilizing developmental landmarks to visually stages embryos. A total of 17,993 genes were identified in the European species and 15,295 were identified in the North American species, with 11,551 orthologs identified between the two. I utilized the transcription start site (TSS) profiling method STRIPE-seq to identify promoter motifs and RNA-seq to survey mRNA concentration at each stage, generating a wealth of genetic data. The methodology for library construction and the dataset generated therein provide an informative basis for further comparative developmental studies and the elucidation of full gene functionality in an emerging model organism.
ContributorsWalls, Sarah (Author) / Lynch, Michael (Thesis advisor) / Raborn, R. Taylor (Committee member) / Mangoni, Marco (Committee member) / Harris, Robin (Committee member) / Arizona State University (Publisher)
Created2022
Description
Regulation of transcription initiation is a critical factor in the emergence of diverse biological phenotypes, including the development of multiple cell types from a single genotype, the ability of organisms to respond to environmental cues, and the rise of heritable diseases. Transcription initiation is regulated in large part by promoter regions of DNA. The identification and characterization of cis-regulatory regions, and understanding how these sequences differ across species, is a question of interest in evolution. To address this topic, I used the model organism Daphnia pulex, a well-characterized microcrustacean with an annotated genome sequence and selected a distribution of well-defined populations geographically located throughout the Midwestern US, Oregon, and Canada. Using isolated total RNA from adult, female Daphnia originating from the selected populations as well as a related taxon, Daphnia pulicaria (200,000 years diverged from D. pulex), I identified an average of over 14,000 (n=14,471) promoter regions using a novel transcription start site (TSS) profiling method, STRIPE-seq. Through the identification of sequence architecture, promoter class, conservation, and transcription start region (TSR) width, of cis-regulatory regions across the aforementioned Daphnia populations, I constructed a system for the study of promoter evolution, enabling a robust interpretation of promoter evolution in the context of the population-genetic environment. The methodology presented, coupled with the generated dataset, provides a foundation for the study of the evolution of promoters across both species and populations.
ContributorsSnyder, Shannon (Author) / Lynch, Michael (Thesis advisor) / Harris, Robin (Committee member) / Raborn, Randolph T (Committee member) / Wideman, Jeremy (Committee member) / Arizona State University (Publisher)
Created2020