Transposable element content is associated with total genome size and host taxonomy in sulfur-oxidizing bacterial endosymbionts.

TE abundance in sulfur-oxidizing Gammaproteobacteria endosymbionts is significantly correlated with genome size, host family, and lifestyle, while phylogeny and habitat type show no demonstrated association.

• Why it matters: Marine chemosynthetic symbioses are understudied for transposable element prevalence and function, limiting understanding of how TE dynamics may contribute to adaptation in chemically reducing environments.
• What they did: The study analyzed TE content and transposase gene flanking regions across genomes of sulfur-oxidizing Gammaproteobacteria from animal-associated symbioses in diverse chemically reducing habitats, testing associations with phylogeny, habitat type, genome size, host family, and lifestyle.
• The result: Almost all vesicomyid clam symbionts lacked TEs, whereas mytilid symbionts had the highest TE abundance; many transposase genes were flanked by DNA replication/repair, membrane transport, and prokaryotic defense genes, supporting hypotheses about adaptation-related TE cargo.