Doctor of Philosophy in Biology
In the
School of Biological Sciences
Chris Johnson
Will defend his dissertation
Investigating the Mechanisms Underlying Metamorphosis in the Chordate Ciona robusta
18, 4, 2024
2:30 PM
Krone Engineered Biosystems Building (EBB) CHOA Room 1005
https://gatech.zoom.us/j/93986623573?pwd=eURpcHRrcXFwUENmcWNXRFBKZlpFUT09
Thesis Advisor:
Alberto Stolfi, Ph.D.
School of Biological Sciences
Georgia Institute of Technology
Committee Members:
Annalise Paaby, Ph.D.
School of Biological Sciences
Georgia Institute of Technology
Brian Hammer, Ph.D.
School of Biological Sciences
Georgia Institute of Technology
William Ratcliff, Ph.D.
School of Biological Sciences
Georgia Institute of Technology
Pengpeng Bi, Ph.D.
Department of Genetics and Center for Molecular Medicine
University of Georgia
ABSTRACT:
Tunicates are our closes living invertebrate relative, and as such, have given us tremendous insight on tunicate/vertebrate development and evolution. For this presentation, I discuss two projects that are tied together and contribute to the ongoing investigation underlying metamorphosis in tunicates.
The first chapter discusses our work on the transcriptional regulation governing the pattering of cells comprising the three sensory adhesive papillae of the Ciona robusta larva. Through the discovery and use of novel genetic markers and reporter constructs, we visualized and tracked the differentiation of various papilla cell types which range from collocytes responsible for secreting adhesive material, to ciliated neurons initiating metamorphosis and axial columnar cells potentially possessing chemosensory and contractile properties. Using CRISPR/Cas9, overexpression, and pharmacological perturbations, we identified the molecular mechanisms underlying the specification of these cell types and their contributions to metamorphic processes.
The second chapter describes the transcriptional regulation of adult Ciona muscle cell fusion. In vertebrates, all skeletal muscles form multinucleated myofibers through myoblast fusion. In tunicates like Ciona, only adult muscles form multinucleated fibers through cell fusion, while larvae have mononucleated muscles instead. I show that this is achieved through combinatorial regulation that activates the expression of a key myoblast fusion factor only in adult muscles.
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