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Questions and Answers
Which signaling proteins family is involved in a wide variety of processes, most noticeably in normal development?
What kind of factors are Wnts in the context of embryonic development?
Which enzyme regulates the coordinated regulation of the anterior-posterior axis in zebrafish, specifically in the neural ectoderm patterning?
What is retinoic acid's role as a morphogen in cell regulation?
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Where is the gene encoding the enzyme cyp26, which is pivotal in zebrafish's neural ectoderm patterning, expressed?
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Which factor plays a key role in regulating cell properties dependent on its concentration during embryonic development?
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What is the role of retinoic acid-4-hydroxylase in hindbrain development?
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How do FGFs and Wnts reciprocate the inhibition by retinoic acid-4-hydroxylase?
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What role do NODAL signaling and Pitx2 transcription factor play in zebrafish left-right axis development?
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How is the left-right asymmetry controlled in zebrafish embryos?
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What happens when ciliary function is blocked in zebrafish embryos?
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How does reciprocal inhibition create a border between posterior and anterior gene expression zones?
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What is responsible for imparting dorsal-ventral patterning to the developing neural tube in the text?
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Which major phase in AP patterning involves the formation of muscles tissue blocks called somites in the vertebrate embryo?
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Where is the part of a very important signaling center called the organizer first specified in zebrafish?
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During which phase does the initiation phase occur in zebrafish in relation to gastrulation?
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Which molecule is NOT mentioned as being involved in AP patterning in the text?
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Which process involves cells migrating towards the animal pole where the brain forms?
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Study Notes
Gastrulation and AP Axis Formation
- The most posterior cells migrate towards the vegetal pole, forming the tailbud, and the AP axis aligns with the animal-vegetal pole by the end of gastrulation.
- The patterning of neural ectoderm along the AP axis in zebrafish involves the interplay of FGF, Wnts, and retinoic acid.
Regulation of AP Axis
- Retinoic acid (RA) acts as a morphogen, regulating cell properties depending on its concentration:
- Cells receiving low RA express anterior genes
- Cells receiving high RA express posterior genes
- Cells receiving intermediate RA express genes characteristic of cells between anterior and posterior regions
- Retinoic acid-4-hydroxylase (cyp26) degrades RA and is expressed at the anterior end of the embryo, preventing accumulation of RA and blocking posterior gene expression.
Dorsal-Ventral Patterning
- Shh secreted from the notochord imparts dorsal-ventral patterning to the developing neural tube.
Anterior-Posterior Axis
- The AP axis is the first embryonic axis to arise in evolution, allowing animals to move unidirectionally.
- In modern bilaterians, the AP axis corresponds to the head-tail axis.
- Different animals use various mechanisms to create this axis in the early embryo.
AP Axis Formation in Zebrafish
- AP patterning in the vertebrate embryo can be divided into two phases:
- Initiation phase: embryo divided into head and body
- Elaboration phase: body forms towards the posterior end, forming the trunk and tail
- In zebrafish, the initiation phase occurs prior to gastrulation, and the different territories of the final body plan can be roughly mapped onto the embryo.
Left-Right Axis Formation
- The series of embryonic development that distinguish the left and right sides of the embryo include:
- Direction of axial rotation
- Morphogenesis of individual organs
- Organ placement
- In vertebrates, the left and right sides develop differently, with the heart on the left side in fish.
- NODAL signaling and the Pitx2 transcription factor provide left-right asymmetry information to cells on the left side of the body.
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Description
Learn about the migration of cells during gastrulation in zebrafish and the regulation of neural ectoderm patterning along the anterior-posterior axis. Explore how factors like FGF, Wnts, and Retinoic acid influence the development of these structures.
