Terminal-Repeat Retrotransposons in Miniature (TRIMs) in bivalves

Area of Science:

• Genomics
• Molecular Biology
• Marine Biology

Background:

• Terminal Repeat Retrotransposons in Miniature (TRIMs) are small, non-autonomous LTR retrotransposons.
• Their study has been primarily confined to plant genomes.
• Bivalves are ecologically and commercially vital marine invertebrates with growing genomic research interest.

Purpose of the Study:

• To report the first identification and characterization of a TRIM element in bivalve species.
• To investigate the prevalence and structural variations of this element across different bivalve taxa.
• To explore the evolutionary history and potential spread mechanisms of TRIM elements in bivalves.

Main Methods:

• Bioinformatic analysis of genomic data from multiple bivalve species.
• Identification and characterization of TRIM element sequences.
• Phylogenetic analysis to infer evolutionary relationships.
• Comparative genomics to assess distribution and variation.

Main Results:

• The novel bivalve TRIM (biv-TRIM) element was identified in numerous bivalve species, including Donax trunculus and Mytilus galloprovincialis.
• Detected variations included canonical elements, solo-terminal direct repeats (TDRs), and tandem repeats.
• biv-TRIM elements constitute less than 1% of the genome in each surveyed species.
• Phylogenetic analysis revealed complex clustering patterns, suggesting horizontal gene transfer.

Conclusions:

• This study presents the first evidence of TRIM elements in the kingdom Animalia, specifically within Bivalvia.
• The findings highlight the diversity and evolutionary dynamics of TRIM elements in marine invertebrates.
• Horizontal transfer is indicated as a potential mechanism for the spread of biv-TRIM elements across bivalve populations.