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Gene activation in the amphibian mesoderm
1CRC Molecular Embryology Group, Department of Zoology, Cambridge, UK.
Development (Cambridge, England). Supplement
|January 1, 1991
Summary
Researchers identified two key genes, Xenopus MyoD (XMyoD) and Xtwi, involved in early amphibian mesoderm development. XMyoD initiates muscle differentiation, while Xtwi plays a broader role in mesodermal fates.
Area of Science:
- Developmental Biology
- Molecular Genetics
- Amphibian Embryogenesis
Background:
- Cell potency in amphibian development is restricted by inductive signaling events.
- The earliest induction involves vegetal cells influencing animal hemisphere cells towards mesodermal fates.
- Understanding early mesodermal markers is crucial for deciphering developmental pathways.
Purpose of the Study:
- To identify and characterize early molecular markers of mesodermal differentiation in Xenopus laevis.
- To investigate the roles of novel helix-loop-helix genes, Xenopus MyoD (XMyoD) and Xtwi, in mesodermal development.
- To explore the potential of XMyoD in initiating muscle differentiation.
Main Methods:
- Identification and characterization of two novel mRNA markers encoding DNA-binding proteins.
- Analysis of XMyoD and Xtwi gene expression patterns during early Xenopus development.
- Microinjection of synthetic XMyoD RNA into animal cap cells to assess its inductive capacity.
Main Results:
- Xenopus MyoD (XMyoD) mRNA accumulation precedes cardiac actin, indicating its role in initiating muscle lineage.
- XMyoD injection into animal cap cells induced muscle-specific gene expression but not full differentiation.
- Xtwi is expressed broadly in early mesoderm but not in myotomes, and later in neural crest.
Conclusions:
- XMyoD is a key regulator initiating muscle differentiation in Xenopus development.
- Full myogenesis requires additional factors beyond XMyoD's direct action.
- Xtwi plays a significant role in early mesodermal patterning and later neural crest development.