Related Experiment Video
Updated: Jul 10, 2026
06:47
Assessing Primary Neurogenesis in Xenopus Embryos Using Immunostaining
Published on: April 12, 2016
Distinct elements of the xsna promoter are required for mesodermal and ectodermal expression
R Mayor1, L J Essex, M F Bennett
1Laboratory of Developmental Biology, National Institute for Medical Research, Mill Hill, London, UK.
Development (Cambridge, England)
|November 1, 1993
Summary
Xenopus snail homologue (Xsna) gene expression patterns reveal early mesoderm subdivision and neural crest development. Promoter analysis identified specific DNA sequences regulating Xsna
Area of Science:
- Developmental biology
- Molecular genetics
- Xenopus laevis research
Background:
- The Xenopus snail homologue (Xsna) is crucial for embryonic development, with expression in both mesoderm and ectoderm.
- Understanding Xsna's spatiotemporal expression is key to deciphering early embryonic patterning and cell fate determination.
Purpose of the Study:
- To investigate the regulatory mechanisms underlying Xsna gene expression patterns during Xenopus embryogenesis.
- To identify specific promoter elements responsible for driving Xsna expression in mesodermal and ectodermal tissues.
Main Methods:
- In situ hybridization to visualize endogenous Xsna mRNA distribution.
- Reporter gene assays using 5' upstream sequences of the Xsna gene fused to a reporter construct (e.g., beta-galactosidase).
- Deletion analysis of the Xsna promoter to pinpoint regulatory regions.
Main Results:
- Xsna expression delineates mesodermal subdivisions and marks the neural plate border, including prospective neural crest and neural tube roof.
- A 115-base pair upstream element (-160 to -45) is sufficient for driving appropriate reporter gene expression.
- Specific sequences within the 5' region (-112 to -97 for mesoderm, -96 to -44 for ectoderm) are required for distinct expression patterns.
Conclusions:
- The Xsna promoter contains critical elements that dictate its precise expression in mesoderm and ectoderm during Xenopus development.
- These regulatory elements are essential for establishing early embryonic tissue boundaries and cell identities, including neural crest formation.
Related Concept Videos
01:51Determination
During embryogenesis, cells become progressively committed to different fates through a two-step process: specification followed by determination. Specification is demonstrated by removing a segment of an early embryo, “neutrally” culturing the tissue in vitro—for example, in a petri dish with simple medium—and then observing the derivatives. If the cultured region gives rise to cell types that it would normally generate in the embryo, this means that it is specified. In contrast, determination...
03:17Inheritance of Chromatin Structures
Epigenetics is the study of inherited changes in a cell's phenotype without changing the DNA sequences. It provides a form of memory for the differential gene expression pattern to maintain cell lineage, position-effect variegation, dosage compensation, and maintenance of chromatin structures such as telomeres and centromeres. For example, the structure and location of the centromere on chromosomes are epigenetically inherited. Its functionality is not dictated or ensured by the underlying DNA...
02:40The Eukaryotic Promoter Region
The eukaryotic promoter region is a segment of DNA located upstream of a gene. It contains an RNA polymerase binding site, a transcription start site, and several cis-regulatory sequences. The proximal promoter region is located in the vicinity of the gene and has cis-regulatory sequences and the core promoter. The core promoter is the binding site for RNA polymerase and is usually located between -35 and +35 nucleotides from the transcription start site. The distal promoter regions are...
02:23Master Transcription Regulators
Master transcription regulators are regulatory proteins that are predominantly responsible for regulating the expression of multiple genes. Often these genes work in concert to drive a complex process. Activation of a master transcription regulator can lead to a cascade of transcriptional activation necessary for that outcome. These regulators can directly bind to the regulatory sequences of the various genes involved, or they can indirectly regulate transcription by binding to regulatory...
02:45The Ratio of X Chromosome to Autosomes
In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined by the ratio of the number of X chromosomes to the number of sets of autosomes. The Y chromosome in Drosophila is active but does not determine sex. It contains genes responsible for the production of sperms in adult flies.
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
02:40The Eukaryotic Promoter Region
The eukaryotic promoter region is a segment of DNA located upstream of a gene. It contains an RNA polymerase binding site, a transcription start site, and several cis-regulatory sequences. The proximal promoter region is located in the vicinity of the gene and has cis-regulatory sequences and the core promoter. The core promoter is the binding site for RNA polymerase and is usually located between -35 and +35 nucleotides from the transcription start site. The distal promoter regions are...