Related Experiment Video
Updated: May 20, 2026
04:52
Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
Unstable microsatellite repeats facilitate rapid evolution of coding and regulatory sequences
A Jansen1, R Gemayel, K J Verstrepen
1Laboratory for Systems Biology, Centre of Microbial and Plant Genetics, KU Leuven, Heverlee, Belgium.
Genome Dynamics
|July 5, 2012
Summary
Variable tandem repeats, once dismissed as "junk DNA," are now recognized as crucial functional elements. These sequences drive rapid adaptation and evolution by conferring evolvability, bridging genetic and epigenetic changes.
Area of Science:
- Genetics
- Evolutionary Biology
- Molecular Biology
Background:
- Tandem repeats, also known as satellite repeats, are highly variable DNA sequences prone to alterations via replication or recombination.
- These low-complexity, unstable sequences have historically been misclassified as non-functional 'junk DNA'.
- Emerging evidence indicates their presence in regulatory regions of stress-responsive genes and within genes encoding critical cellular proteins.
Purpose of the Study:
- To re-evaluate the functional significance of variable tandem repeats.
- To explore the role of tandem repeats in phenotypic variability and adaptation.
- To understand how tandem repeats contribute to evolvability.
Main Methods:
- Comparative sequence analysis to identify tandem repeats in gene promoters and coding regions.
- Phenotypic analysis across different organisms to correlate repeat variation with observable traits.
- Examination of the mutational dynamics of tandem repeats in relation to genetic and epigenetic changes.
Main Results:
- Tandem repeats are frequently located in promoters of stress-induced genes and coding regions of cell-surface/regulatory proteins.
- Variations in these repeats are linked to significant phenotypic diversity, including microbial cell-surface changes, fly circadian clock regulation, and mammalian morphological plasticity.
- Tandem repeat dynamics facilitate rapid adaptation to environmental changes, conferring 'evolvability'.
Conclusions:
- Variable tandem repeats are not 'junk DNA' but functional elements crucial for adaptation and evolution.
- These repeats offer a unique mutational mechanism, bridging the gap between stable genetic mutations and reversible epigenetic inheritance.
- The inherent instability and reversibility of tandem repeats provide a powerful tool for organisms to rapidly adjust to environmental pressures.
Related Concept Videos
02:05Gene Evolution - Fast or Slow?
The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
In contrast, regions which code...
In contrast, regions which code...
02:05Gene Evolution - Fast or Slow?
The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
In contrast, regions which code...
In contrast, regions which code...
02:32Exon Recombination
The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Exon shuffling follows “splice frame rules.” Each exon has three reading...
02:02Cis-regulatory Sequences
Cis-regulatory sequences are short fragments of non-coding DNA that are present on the same chromosomes as the genes that they regulate. These fragments serve as binding sites for transcriptional regulators, proteins that are responsible for controlling gene transcription and differential gene expression across cell types in eukaryotes. Cis-regulatory sequences can be close to the gene of interest or thousands of bases away in the DNA sequence; however, those sequences that are further away are...
02:02Cis-regulatory Sequences
Cis-regulatory sequences are short fragments of non-coding DNA that are present on the same chromosomes as the genes that they regulate. These fragments serve as binding sites for transcriptional regulators, proteins that are responsible for controlling gene transcription and differential gene expression across cell types in eukaryotes. Cis-regulatory sequences can be close to the gene of interest or thousands of bases away in the DNA sequence; however, those sequences that are further away are...
02:51Multi-species Conserved Sequences
Next-generation sequencing technologies have created large genomic databases of a variety of animals and plants. Ever since the human genome project was completed, scientists studied the genome of primates, mammals, and other phylogenetically distant living beings. Such large-scale studies have provided new insights into the evolutionary relationship between organisms.
Although the genome of each species varies greatly from each other, a few sequences are highly conserved. Such conserved DNA...
Although the genome of each species varies greatly from each other, a few sequences are highly conserved. Such conserved DNA...