Ants branched into thousands of new species after the dinosaurs died, and a new study links that burst to jumping genes in their DNA.
About Jumping Genes:
Jumping genes, scientifically called transposable elements (TEs) or transposons, are DNA sequences that move from one location on the genome to another.
They are widespread in both prokaryotes and eukaryotes, often making up significant portions of an organism's genetic material.
In humans, for instance, transposons account for approximately 50% of the genome, whereas in corn, they account for up to 90%.
Types: Transposons can be grouped into distinct types based on 2 main criteria: their mechanism of movement and their independence.
They are classified as retrotransposons or DNA transposons, depending on how they move within the genome.
They are classified as autonomous or non-autonomous, based on whether they require other transposons for their mobility.
Transposons have a dual nature as both a threat to genome stability and a driver of genetic diversity.
On the harmful side, they can inactivate genes or disrupt gene expression patterns by inserting into regulatory or coding regions, leading to diseases such as hemophilia, hypercholesterolemia and various cancers.
However, transposons also play a key part in evolution.
For instance, in plants, environmental stresses like climate change can trigger increased transposon activity, potentially giving rise to adaptive mutations that enhance survival.
To counter the potentially damaging effects of transposons, most organisms have evolved epigenetic mechanisms to regulate their activity.
In humans, for example, regions of the genome rich in transposons are often tightly condensed so that the transcription machinery cannot access them.
This densely packed DNA is called heterochromatin, and it is formed through histone modifications (changes to the histone proteins around which the DNA is wound) and DNA methylation (the addition of methyl groups to cytosine bases).
Other silencing mechanisms are based on RNAi or small RNAs, such as piRNAs, miRNAs, or siRNAs, to specifically target and inactivate transposons.
While most TEs are located far away from genes in areas of the chromosome that can be thought of as gene deserts, some are located near genes and even target gene-rich regions.
Transposons can also be useful tools in the lab, with applications in mutagenesis, transgenesis, and gene therapy.
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