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Zebrafish organizer development and germ-layer formation require nodal-related signals Feldman et al Nature 1998 Presented by Maggie Bach and Aparna Vidyasagar. Outline. Introduction and Background Questions What are the mutant phenotypes? To where does the gene map?
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Zebrafish organizer development and germ-layer formation require nodal-related signals Feldman et al Nature 1998 Presented by Maggie Bach and Aparna Vidyasagar
Outline • Introduction and Background • Questions • What are the mutant phenotypes? • To where does the gene map? • Can sqt induce dorsal mesoderm? • Conclusion
Big Idea • Characterize the Squint gene and its role in development
Background • Blastula • Gastrula • Mesoderm – forms bones, muscles, organs • Endoderm – digestive and respiratory tract • Ectoderm – epidermis, nervous system
Fate Map of the Deep Cell Layer at Gastrula Onset Kimmel et al., 1955 Developmental Dynamics
gsc • Goosecoid • Dorsal mesodermal marker • Expressed in organizer
Nodal Signals • Expressed in YSL • Source of mesoderm-inducing factors • TGF-β related signals
Question 1 What are the different mutant phenotypes?
sqt– • Cyclopia • Expression of gsc reduced at blastula stages • gsc expression increases as gastrulation progresses • No Zebrafish organizer region • Spontaneous recessive enhancer of cyc
cyc– • Cyclopia
sqt– cyc– • No mesoderm development • Muscle differentiation can occur in tail • Lack of gsc expression • No Zebrafish organizer region • Morphogenesis of mesoderm and endoderm is abnormal