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14:50
Understanding Early Organogenesis Using a Simplified In Situ Hybridization Protocol in Xenopus
Published on: January 12, 2015
Mapping gene expression in two Xenopus species: evolutionary constraints and developmental flexibility.
Itai Yanai1, Leonid Peshkin, Paul Jorgensen
1Department of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel.
Developmental Cell
|April 19, 2011
Summary
Gene expression changes drive morphological evolution, with conserved transcriptomes between Xenopus species. Most differences involved gene expression levels, particularly in early development, not timing (heterochrony).
Area of Science:
- Developmental Biology
- Evolutionary Biology
- Comparative Genomics
Background:
- Gene expression changes are hypothesized to be crucial for morphological evolution.
- The precise nature and extent of these expression differences remain largely unknown.
- Amphibians like Xenopus offer models for studying conserved developmental processes.
Purpose of the Study:
- To compare the transcriptomes of Xenopus laevis and Xenopus tropicalis.
- To investigate the extent of gene expression conservation and divergence.
- To identify patterns in changes in gene expression levels and timing (heterochrony).
Main Methods:
- Comparative transcriptome analysis of Xenopus laevis and Xenopus tropicalis.
- Identification and comparison of expressed orthologs between the two species.
- Analysis of differences in gene expression levels and temporal patterns (heterochrony).
Main Results:
- Strong conservation of gene expression was observed in most expressed orthologs.
- Significant changes were found in gene expression levels, concentrated in early embryonic stages.
- Changes in expression timing (heterochrony) were less common and associated with environmental response pathways.
Conclusions:
- Despite significant evolutionary divergence (~30-90 million years), Xenopus transcriptomes show remarkable conservation.
- Evolutionary rate differences across developmental stages may stem from stabilized cell fate determination in later stages.
- Expression level changes, particularly in early development, appear more prevalent than heterochrony in driving morphological evolution.
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