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Publication Date

2022-05-09

First Advisor

Laura A. Katz

Document Type

Honors Project

Degree Name

Bachelor of Arts

Department

Biological Sciences

Keywords

ciliate, macronuclei, micronuclei, nuclear architecture, nuclear dualism, scrambling, polyploid, ploidy, iregular chromosomes, life cycle variability, evolution, LECA, DNA

Abstract

Genomes that deviate from the textbook depictions of simplistic haploid/diploid cycling are not that uncommon. Foundational concepts of biology taught in early education form our rigid understanding of life. Especially within the realm of life cycles and genomes, variability is often ignored to simplify biological concepts. In addition to the lack of diversity in these models, unicellular organisms - especially microeukaryotes (aka protists) - are often neglected. While protists remain a largely understudied clade of organisms, preliminary data have shown that they contain significant diversity in terms of life cycle variability and nuclear architecture amongst other organisms on the tree of life. One clade of microeukaryotes that exemplifies this diversity is the ciliates. Defined by their nuclear dualism, or the presence of a somatic macronucleus and germline micronucleus within a single cell, ciliates have become a model organism for research into genome dynamics. Here, I explore the nuclear architecture of ciliates, examining somatic and germline distinctions in hopes of better understanding their genome plasticity and diversity. In my first chapter, I demonstrate that uncultivable ciliates are a challenging clade of organisms to analyze bioinformatically because 1) they contain microbiomes and 2) their rDNA is tough to identify due to the difficulty of fully sequencing their large genomes. This work expands knowledge of the nature of ciliate genome architecture and provides further avenues of research in this field. In my second chapter, a literature review, I state that life cycle and genomic variability are not limited to just ciliates as unusual ploidy cycles occur all throughout the eukaryotic tree of life. Overall, the consensus is that “irregular” genomes are not quite as unusual as we are led to believe.

Rights

©2022 Wumei Blanche. Access limited to the Smith College community and other researchers while on campus. Smith College community members also may access from off-campus using a Smith College log-in. Other off-campus researchers may request a copy through Interlibrary Loan for personal use.

Language

English

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