{"doi":"10.1093/gbe/evaf061","title":"Repeated Evolution of Transcript Dosage Compensation of Independently Formed Nematode Neo-X Chromosomes","abstract":"Ohno proposed that, during the origin of X/Y sex chromosomes from a pair of autosomes, X-linked genes must double their per-allele expressions to compensate for the degeneration of their Y homologs. Whether Ohno's hypothesis holds in the nematode Caenorhabditis elegans remains unresolved despite that C. elegans is a model for studying between-sex X chromosome dosage compensation. Genome sequencing revealed independent fusions of an ancestrally autosomal linkage group to the X chromosome in C. elegans and Brugia malayi, two species belonging to different suborders of the order Rhabditida, allowing testing Ohno's hypothesis in repeated origins of neo-X chromosomes from the same autosomal linkage group. For each C. elegans X-linked gene and its autosomal ortholog in Pristionchus pacificus, we computed the X:AA ratio in transcript level and observed a median of ∼1. The same is true for B. malayi X-linked genes when compared with their autosomal orthologs in Dirofilaria immitis. We find a significant enrichment of presumably dosage-sensitive transcription factor genes among the autosomal genes of P. pacificus (or D. immitis) that become X-linked in C. elegans (or B. malayi), but the results are mixed for other groups of presumably dosage-sensitive genes, providing a partial support to the hypothesis that X upregulation depends on the prevalence of dosage-sensitive genes in the proto-X. We conclude that, unlike the virtual absence of X upregulation at the transcript level in eutherian mammals, Ohno's hypothesis is strongly supported in both nematode lineages investigated.","journal":"Genome Biology and Evolution","year":2025,"id":552219,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9539,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":652089,"name":"Siliang Song","orcid":"0000-0002-4658-5062","position":1,"is_corresponding":false},{"id":275488,"name":"Jianzhi Zhang","orcid":"0000-0001-6141-1290","position":2,"is_corresponding":false},{"id":1448399,"name":"Jiachen Li","orcid":"0000-0001-5389-6128","position":0,"is_corresponding":true}],"reference_count":49,"raw_metadata":null,"created_at":"2026-07-19T02:54:33.203144Z","pmid":"40171700","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}