{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T13:37:49Z","timestamp":1770730669675,"version":"3.49.0"},"reference-count":65,"publisher":"S. Karger AG","issue":"1","license":[{"start":{"date-parts":[[2025,9,29]],"date-time":"2025-09-29T00:00:00Z","timestamp":1759104000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"},{"start":{"date-parts":[[2025,9,29]],"date-time":"2025-09-29T00:00:00Z","timestamp":1759104000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cytogenet Genome Res"],"abstract":"<jats:p>Introduction: Sex chromosomes often evolve through suppressed recombination and accumulation of transposable elements (TEs) on the sex-limited chromosome, leading to divergence and eventual degeneration. The clam shrimp Eulimnadia texana possesses proto-sex chromosomes (Z and W) at an early evolutionary stage, providing a unique opportunity to examine the initial genomic changes underlying sex chromosome differentiation. Additionally, both sex chromosomes are expressed in homogametic ZZ and WW shrimp, allowing a regular expression of both sex chromosomes in homozygotes. Methods: We analyzed newly assembled ZZ (male) and previously published WW (hermaphrodite) genomes of E. texana. Sex-linked markers were mapped to identify the Z chromosome. TEs were annotated using a species-specific repeat library and RepeatMasker. The Z and W chromosomes were divided into bins and randomization tests compared TE accumulation between the sex chromosomes as well as between corresponding regions within these two chromosomes; the latter was focused on the putative sex-determining regions of both the Z and W. Kimura distance-based analyses were used to estimate TE age divergence. Results: The Z chromosome showed no significant TE enrichment relative to autosomes but was enriched for DNA transposons. The W chromosome exhibited significantly higher retrotransposon (LTR and LINE) accumulation. Only the sex-determining region of the W showed significantly elevated retrotransposon content compared to the Z. TE age landscapes indicated recent bursts of retrotransposon activity on the W. Conclusion: These findings support theoretical predictions that retrotransposons accumulate in non-recombining regions, while DNA transposons are associated with recombining chromosomes. The W chromosome of E. texana shows early signs of differentiation, with localized retrotransposon buildup, while the Z remains autosome-like. This study highlights E. texana as a valuable model for understanding the genomic mechanisms of early sex chromosome evolution.<\/jats:p>","DOI":"10.1159\/000548721","type":"journal-article","created":{"date-parts":[[2025,9,29]],"date-time":"2025-09-29T16:00:59Z","timestamp":1759161659000},"page":"30-45","source":"Crossref","is-referenced-by-count":0,"title":["Transposable Elements and Sex Chromosome Evolution in Eulimnadia texana"],"prefix":"10.1159","volume":"166","author":[{"given":"Chathumadavi","family":"Ediriweera","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Stephen 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