Author ORCID Identifier

https://orcid.org/0009-0003-8864-6219

Semester

Fall

Date of Graduation

2024

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

Stephen Valentine

Abstract

Tsetse flies (Glossina morsitans), which are the obligate vectors of Old-World trypanosomes (Trypanosoma spp.) that cause African trypanosomiasis, have a bacteriome that houses the intracellular endosymbiont Wigglesworthia glossinidia. The ancient coevolution of these species has led to the integration of Wigglesworthia metabolism into tsetse physiology and a subsequent reliance on nutrient exchange for maintaining the fitness of both partners. The establishment of this obligate mutualism has facilitated the emergence of feedback mechanisms that stabilize the symbiosis, such as that which involves the exchange of L-serine and B vitamins. The Gammaproteobacteria Wigglesworthia supplement B vitamins lacking in the hematophagous diet of the tsetse host and, in return, L-serine, which requires B vitamins for its synthesis by tsetse, is provisioned to Wigglesworthia. Here, we identify potential points of weakness in the tsetse-Wigglesworthia symbiosis through L-serine biosynthesis and transport gene expression analyses. L-serine biosynthesis was shown to occur predominantly outside of the bacteriome, indicating the need for B6 to be transported out of its bacteriome origin and into other abdominal tissues. The inhibition of pyridoxal kinase, which converts B6 into its active form following its diffusion into cells, may be used to prevent L-serine synthesis outside of the bacteriome. In hyposymbiotic tsetse, Wigglesworthia do not express SdaC, their sole putative L-serine transporter, despite maintenance of wild-type L-serine biosynthesis levels, which suggests that reduced populations of Wigglesworthia may fail to regulate bacteriome L-serine levels. The bioinformatic characterization of Wigglesworthia SdaC by comparison to other gram-negative bacteria suggests that reduced Wigglesworthia populations may also fail to achieve self-recognition, which could impact vertical transmission. Difficulties in developing treatments for and vaccinations against trypanosome infections has led to a focus on strategies for reducing tsetse populations to prevent trypanosomiasis. These insights into the stability of the tsetse-Wigglesworthia symbiosis provide novel targets for reducing tsetse fitness.

Download

Share

COinS