Discovery of Ultra-Conserved Elements (UCEs)
Researchers discovered that nearly 500 segments of the human genome have remained unchanged for 80 million years, shared by humans, rats, and mice.
These segments, known as Ultra-Conserved Elements (UCEs), are also conserved in other species like chickens and fish.
The finding of UCEs raised the question of what biological constraint keeps them intact over such long evolutionary periods, as scientists initially had no clear answer.
Function of UCEs
The UCE discovered in the Tra2b gene plays a key role in regulating protein production by limiting the amount of Tra2 protein in cells.
This process is critical for maintaining balance in gene expression, as overproduction of the Tra2 protein leads to infertility in mice.
UCEs like the one in the Tra2b gene are essential in preventing harmful biological effects, demonstrating that small genetic changes could have large consequences for survival and reproduction.
Role of Poison Exon
The UCE in the Tra2b gene functions as a "poison exon," which, when included in mRNA, introduces stop codons that cause the ribosome to halt protein synthesis.
This prevents overaccumulation of the Tra2 protein, which is crucial in controlling the proper functioning of sperm-producing cells.
The poison exon acts like a built-in safeguard mechanism, ensuring that proteins are produced only in the required amounts to maintain cellular health and reproductive function.
Experimental Findings
Researchers used genetic engineering to delete the UCE in the mouse testes, resulting in the overproduction of the Tra2 protein and causing infertility in the mice.
The removal of the UCE showed that its function in limiting protein production is essential for sperm production and fertility.
This study further suggests that even small changes in UCEs, such as a single base-pair alteration, could disrupt the biological function, making the UCEs crucial for maintaining reproductive health across generations.
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