Ancient segmentally duplicated LCORL retrocopies in equids.

Area of Science:

• Genomics
• Evolutionary Biology
• Molecular Biology

Background:

• LINE-1 elements are active transposable elements that create retrocopies.
• Retrocopy number variants (retroCNVs) contribute to genetic diversity between individuals.
• Understanding retroCNV formation and function is crucial for evolutionary studies.

Purpose of the Study:

• To discover and characterize retroCNVs in equids.
• To investigate the role of Ligand Dependent Nuclear Receptor Corepressor Like (LCORL) retrocopies in equid evolution.
• To determine the evolutionary timeline and functional significance of LCORL retrotransposition.

Main Methods:

• RetroCNV discovery in 86 equid samples.
• Comparative analysis of retroCNV distribution across species.
• Quantification of LCORL retrocopy expression in horses and donkeys.
• Estimation of LCORL retrotransposition timing using phylogenetic analysis.

Main Results:

• Identified 437 retrocopy insertions in equids, with most being species-specific.
• Discovered a conserved segmental amplification of 17-35 LCORL retrocopies in all equids, absent in other perissodactyls.
• LCORL transcripts predominantly originate from retrocopies in horses and donkeys.
• Initial LCORL retrotransposition dated to 18 million years ago, coinciding with key equid evolutionary events.

Conclusions:

• LCORL retrocopy amplification is an ancient structural variant conserved within Equidae.
• High expression levels and ancient origin suggest a functional role for LCORL retrocopies in equid evolution.
• RetroCNVs, particularly LCORL retrocopies, have significantly shaped equid genetic diversity and evolutionary trajectory.