Graduation Semester and Year
Spring 2024
Language
English
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Quantitative Biology
Department
Biology
First Advisor
Sen Xu
Second Advisor
Matthew Walsh
Third Advisor
Jeffery Demuth
Abstract
Daphnia has been used as a key model system for studying ecological changes, evolution, and genomics for the past few decades due to its rapid turnover time in reproduction. The organism possesses two fascinating modes of reproduction: obligate parthenogenesis and cyclical parthenogenesis. This dissertation delves into the intricate reproductive strategies of Daphnia pulex, focusing on hybrid F1s from different reproductive modes. The first aim is to investigate 31 hybrid F1s generated from obligate parthenogenesis (OP) and cyclical parthenogenesis (CP) parental lines. Transcriptomic analysis reveals misexpression patterns and regulatory divergences, highlighting meiosis-related genes like CDC6 as potential parthenogenesis regulators. The second aim is to address CRISPR-Cas gene editing challenges in Daphnia, developing an efficient microinjection method for Cas9 and Cas12a nucleases. Mutational analyses in scarlet mutants uncover complex mutation spectra and germline mosaicism, linking gene editing to pleiotropic effects. The third aim is to explore the origins of OP Daphnia pulex, tracing their lineage from CP isolates. Crossing CP isolates yields F1 hybrids displaying OP characteristics under stress, which has not been reported before. This expands our understanding of parthenogenesis factors in Daphnia. Together, these studies offer a comprehensive view of Daphnia reproduction, inheritance patterns, and regulatory divergence, as well as suggesting precautions for using CRISPR-Cas in Daphnia gene editing.
Keywords
CRISPR, Daphnia, crossing, genetics, genomics, gene editing, parthenogenesis
Disciplines
Computational Biology | Evolution | Genetics | Genomics
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Pham, Thinh, "Understanding the Origin of Parthenogenesis via Crossing and CRISPR Gene Editing in Daphnia pulex" (2024). Biology Dissertations. 2.
https://mavmatrix.uta.edu/biology_dissertations/2