Zebrafish Danio rerio

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ZebrafishDanio rerio
backbone
Longfin mutant
N 1.75 Gb (1.75 x 109bp) on 25 chromosomes,
25,500 ORFs
5 cm
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Life Cycle
Cleavage
expression
Blastula
Immature
Hatchling
expression
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Fertilization
Vitelline layer
Blastodisk
1 cell stage zygote
Yolk cytoplasm
0.7 mm
250 um
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Developmental Timetable
Zygote 0-0.75 hr
Cleavage 0.75-2.25 hr
Blastula 2.25-5.25 hr
Gastrula 5.25-10 hr
Segmentation 10-24 hr
Pharyngula 24-48 hr
Hatchling 48-72 hr
Larval Fish 72 hr
Movie
17 Hours of Development
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Cleavage
2
4
syncytial yolk
of the Blastodisk Cytoplasm
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32
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Blastula
Early
Epiboly
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Fate Map at the Blastula Stage
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Gastrulation Layers the Embryo

• Involution at 50 Epiboly

• Convergence
• (Embryonic Shield Formation)
• Extension

Zygotic gene expression begins Goosecoid
-gtgastrulation No Tail -gt AP axis Snail1 -gt
mesoderm
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Goosecoid
TGF-Beta Wnt/Beta-Catenin
Gooseberry/Bicoid Homeobox Transcription Factor
In situ hybridizations
Xenopus Goosecoid mRNA
Controls Gastrulation
Zebrafish
Xenopus At gastrulation in
zebrafish
Vegetal pole
Goosecoid mRNA
mRNA Microinjection-gt2nd axis
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Notochord Induces Neurulation
ECM Secretion
Epiderm Neural tube Notochord
CNS Spinal cord, Brain Vertebrae Somites Body
Muscles
SSH
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Signaling in the Developing Nervous System
Patched expression
Sonic Hedgehog (the vertebrate Hedgehog ortholog)
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No Tail Expression is a Notochord Marker
movie
P A
(head)
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The Notochord is a Key Landmark in Vertebrate
Evolution
Pikaia 550 MYA
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Segmentation (Somatogenesis)
Delta Jagged
Dorsal Lateral Ventral
Hey1 bHLH expression defines somites
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microRNA (miRNA) expression patterns
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Pharyngula / Hatchling / Larva
Pharyngula Hatchling Larva
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Behavior
Movie
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Effects of ethanol on development
Pigmentation Defects (B) Circulatory Defects
(D) Nervous system and muscular defects (F)
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The Hatchling Heart
3 movie sequences
WT cardiofunk mutant
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The Developing Brain
Movie
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Disease models
emaciation scoliosis
hepatocellular carcinoma
BRAF skin cancer model
Movie
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Regeneration!
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A Few Questions for Thought

• Describe the development of the Zebrafish
  embryo, comparing and contrasting it with the
  other metazoan systems that we have studied.
• What is the role of the blastodisk? How does
  gastrulation shape the fish embryo?
• What is the notochord? What is its function in
  vertebrate development?
• Explain the statement Vertebrates are segmented
  animals too.
• Describe why the Zebrafish is an excellent model
  system for understanding human health and disease.