Ultra-conserved elements (UCEs)

As per the recent study, 80 million years ago, humans, rats, and mice shared a common mammalian ancestor.

• Researchers discovered ~500 UCEs in human genomes that have remained unchanged since then. UCEs are also highly conserved in chickens, dogs, and even some fish species.
• About Ultra-Conserved Elements (UCEs): They are DNA segments that are nearly identical across distantly related organisms which are useful for understanding the evolutionary history of groups of organisms.
• Genetic Engineering Experiment:

o Result: Excessive protein production → sperm-producing cells died → mice became infertile.

o Inference: Any mutation in the UCE affecting protein regulation could lead to loss of sperm production and infertility, preventing the UCE’s transmission across generations.

• Genetics & UCE Function (From Gene to Protein):

o DNA Structure: A double-helix molecule made of four bases, held together by base-pair bonding.

o Genes: Short DNA segments (~a few thousand base-pairs long) that encode proteins.

• Gene Expression Process:

o mRNA Formation: DNA sequence is copied into messenger RNA (mRNA).

o Translation at Ribosome: mRNA guides protein synthesis by stitching amino acids together.

o Stop Codons: Specific sequences in mRNA signal the ribosome to stop protein synthesis.

o Identification of UCEs: Defined as >200 base-pair DNA sequences with perfect identity across human, rat, and mouse genomes.