Date Approved
5-2015
Document Type
Dissertation
Degree Name
PhD in Cell and Molecular Biology
Department
Molecular Biology
College
Graduate School of Biomedical Sciences
Funder
National Science Foundation
First Advisor
Ronald E. Ellis, PhD
Committee Member 1
Katrina Cooper, PhD
Committee Member 2
Eric Moss, PhD
Committee Member 3
Sergei Borukhov, PhD
Committee Member 4
John Pastorino, PhD
Subject(s)
Caenorhabditis; Hermaphroditic Organisms; Self-Fertilization; Mutation
Disciplines
Animal Experimentation and Research | Laboratory and Basic Science Research | Molecular Biology | Molecular Genetics | Organismal Biological Physiology
Abstract
Three hermaphroditic species in the nematode genus Caenorhabditis - C. elegans, C. briggsae and C. tropicalis evolved independently from a male/female ancestor. Thus, the hermaphroditic reproductive system provides an ideal subject for studying the origin of new complex traits. Previous studies implied that this transition required two steps: a mutation that caused XY animals to make sperm, and a mutation that allowed XX spermatids to activate and fertilize oocytes. In this dissertation, I show how sperm activation is regulated in different hermaphroditic species.
First, I used TALENs to create genetic tools for C. briggsae and C. tropicalis. These tools were critical for many of my experiments. In addition, they dramatically speed development of each species as a model system, and can serve as a model for work with other new laboratory animals. These applications of genome-editing tools, such as TALENs or CRISPRs widen our choice of model organisms and facilitate the comparison of gene function between species.
Next, I used TALENs to knock out the orthologs of C. elegans sperm activation in both C. briggsae and C. tropicalis. I found that the ancestral males used two redundant pathways to regulate sperm activation - the SPE-8 tyrosine-kinase pathway and the TRY-5 serine protease pathway. RNAi experiments imply that females do not use either signal. During the evolutionary transition from females to self-fertile hermaphrodites, both C. elegans and C. briggsae co-opted the SPE-8 pathway to activate their sperm, whereas C. tropicalis co-opted the TR Y-5 pathway.
Recommended Citation
Wei, Qing, "Evolution of Sperm Activation in Nematodes" (2015). Graduate School of Biomedical Sciences Theses and Dissertations. 61.
https://rdw.rowan.edu/gsbs_etd/61
Included in
Animal Experimentation and Research Commons, Laboratory and Basic Science Research Commons, Molecular Biology Commons, Molecular Genetics Commons, Organismal Biological Physiology Commons
