Related Experiment Video
Updated: Jun 18, 2026
09:48
Production of Transgenic Xenopus laevis by Restriction Enzyme Mediated Integration and Nuclear Transplantation
Published on: August 21, 2010
Gene switching at Xenopus laevis metamorphosis
Sandeep Mukhi1, Liquan Cai, Donald D Brown
1Carnegie Institution 3520 San Martin Dr., Baltimore, MD 21218, USA.
Developmental Biology
|November 10, 2009
Summary
Thyroid hormone (TH) orchestrates amphibian metamorphosis, driving distinct organ remodeling strategies. Gene switching in some cells and stem cell-like red cell switching in others allow tadpoles to transform into frogs.
Area of Science:
- Developmental Biology
- Cellular Reprogramming
- Endocrinology
Background:
- Amphibian metamorphosis involves extensive organ remodeling.
- Thyroid hormone (TH) is the primary regulator of this complex developmental process.
- Different cell types employ distinct strategies to transition from tadpole to adult forms.
Purpose of the Study:
- To elucidate the diverse cellular mechanisms underlying organ remodeling during amphibian metamorphosis.
- To differentiate between direct gene switching and progenitor-mediated redifferentiation.
- To identify which remodeling strategy most closely resembles stem cell behavior.
Main Methods:
- Comparative analysis of gene expression patterns in various tadpole organs.
- Investigation of DNA replication during cellular transitions.
- Identification of progenitor cell populations involved in tissue renewal.
Main Results:
- Liver, skin, and tail fibroblasts exhibit 'gene switching' – activating adult genes and deactivating larval genes within the same cell, without DNA replication.
- Exocrine pancreas and intestinal epithelium undergo dedifferentiation to progenitor cells, followed by redifferentiation into adult cell types.
- Red blood cell remodeling involves a progenitor stage with DNA replication, transitioning from tadpole to adult globin expression, mimicking a stem cell mechanism.
Conclusions:
- Amphibian metamorphosis employs multiple, distinct cellular remodeling strategies regulated by thyroid hormone.
- Gene switching represents a direct cellular reprogramming, while red cell remodeling utilizes a stem cell-like mechanism.
- Understanding these diverse mechanisms provides insights into fundamental principles of cell fate and tissue regeneration.
More Related Videos
Related Concept Videos
02:32Position-effect Variegation
In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
02:27Background and Environment Affect Phenotype
Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as temperature, oxygen availability, presence of mutagens, that can alter an organism’s phenotype.
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
01:28Forced Transdifferentiation
Transdifferentiation, also known as lineage reprogramming, was first discovered by Selman and Kafatos in 1974 in silkmoths. They observed that the moths’ cuticle-producing cells transformed into salt-producing cells. Many such cases of natural transdifferentiation occur in organisms. In humans, pancreatic alpha cells can become beta cells. In newts, the loss of the eye’s lens causes the pigmented epithelial cells to transdifferentiate into the lens cells.
Artificial transdifferentiation occurs...
Artificial transdifferentiation occurs...
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...