Author ORCID Identifier

https://orcid.org/0000-0002-5572-3922

Semester

Fall

Date of Graduation

2025

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Biology

Committee Chair

Rita Rio

Committee Member

Timothy Driscoll

Committee Member

Dana Huebert Lima

Abstract

Tsetse flies (Diptera: Glossinidae) are the vector of trypanosomes (Trypanosoma spp.), which are responsible for African trypanosomiasis, also known as sleeping sickness. African trypanosomiasis is a significant health and economic burden yet remains a neglected tropical disease. As an obligate blood feeder, tsetse flies are reliant on B vitamin supplementation from intracellular Gammaproteobacteria, Wigglesworthia glossinidia. Folate (B9) is essential for tsetse development and reproduction, as well as DNA methylation in animals. As a reversible modification, DNA methylation typically occurs in a CpG dinucleotide context and can alter gene expression via the restriction of transcription. Across insects, the retention, localization, and establishment of methyl-CpGs are highly variable in comparison to mammals. Diptera (also known as true flies) are largely predicted to have lost the capability to establish DNA methylation. Despite the expected lack of establishing and maintaining genomic DNA methylation, a preliminary 5mc antibody assay suggests minor DNA methylation during tsetse early development. In Chapter 1, I discuss DNA methylation and associated genes in relation to tsetse biology. In Chapter 2, I search for bioinformatic signals of canonical DNA methyltransferases within tsetse and investigate the impact of Wigglesworthia folate provisioning towards the expression of dnmt2, as well as the methyl-CpG “reader” mbd2/3 and the DNA and RNA demethylase tet in Glossina morsitans. Specifically, we examine the expression of these methylation associated genes during pupal development, a period typified by cellular differentiation and changes in DNA methylation patterns in many animals, that culminates in the remodeling of the tsetse body plan. Bioinformatic analyses of the genome and predicted proteomes across tsetse taxonomy affirms the absence of the canonical DNA methyltransferases DNMT1 and DNMT3. Expression of dnmt2 decreases as pupal development progresses, which could mean a reduction in translational accuracy or activity. Similarly, tet expression decreases during pupal development, implying an increase in retention of methyl modifications upon DNA or RNA, or downregulation congruent to dnmt2 activity. In late aposymbiotic pupae, mbd2/3 expression decreased relative to age-matched controls, suggesting that Wigglesworthia may play a role in the tsetse epigenetic landscape despite the fly lacking the canonical means to establish or maintain DNA methylation. Further investigation could reveal how symbiont associations can influence the evolution of epigenetic regulation networks of the host.

Download

Share

COinS