Goldfish transposase Tgf2 presumably from recent horizontal transfer is active

Area of Science:

• Genetics
• Molecular Biology
• Evolutionary Biology

Background:

• Hobo/Activator/Tam3 (hAT) superfamily transposons are crucial for genomic evolution in plants and animals.
• Active transposons are valuable genetic tools, but active vertebrate elements are seldom found.
• The Tgf2 transposon was recently identified in goldfish (Carassius auratus).

Purpose of the Study:

• To investigate the activity and characteristics of the endogenous Tgf2 transposon in goldfish.
• To identify and characterize Tgf2 transposase transcripts and their expression patterns.
• To explore the potential of Tgf2 as a genetic tool in vertebrates.

Main Methods:

• Detection and analysis of Tgf2 transposase mRNA transcripts in various goldfish tissues and developmental stages.
• In vitro transposition assays using injected donor plasmids and capped Tgf2 transposase mRNA.
• Analysis of nonautonomous Tgf2 copies for mutations and deletions.
• Phylogenetic analysis to determine the origin and inheritance pattern of Tgf2.

Main Results:

• The endogenous Tgf2 element was confirmed to transpose within the goldfish genome.
• Seven distinct Tgf2 transposase mRNA transcripts were identified, with varying lengths.
• Tgf2 transposase mRNA expression was observed in embryos, ovaries, mature eggs, and all tested adult tissues.
• High transposition rates (>30%) were achieved in mature eggs with injected donor plasmids, reaching >90% with co-injected capped mRNA.
• Nonautonomous Tgf2 copies exhibited deletions and point mutations, suggesting ongoing activity and evolution.

Conclusions:

• The goldfish Tgf2 transposon is highly active and maintains significant native transposition capability.
• The expression pattern of Tgf2 transposase suggests its involvement in germline and somatic tissues.
• Phylogenetic analysis indicates that Tgf2 likely originated from recent horizontal transfer, not vertical inheritance.
• The active Tgf2 transposon represents a promising new genetic tool for research in vertebrates.