{"doi":"10.1101/2020.11.10.377101","title":"A cohort of <i>Caenorhabditis</i> species lacking the highly conserved <i>let-7</i> microRNA","abstract":"ABSTRACT let-7 is a highly conserved microRNA with critical functions integral to cell fate specification and developmental progression in diverse animals. In Caenorhabditis elegans, let-7 is a component of the heterochronic (developmental timing) gene regulatory network, and loss-of-function mutations of let-7 result in lethality during the larval to adult transition due to misregulation of the conserved let-7 target, lin-41 . To date, no bilaterian animal lacking let-7 has been characterized. In this study, we identify a cohort of nematode species within the genus Caenorhabditis , closely related to C. elegans , that lack the let-7 microRNA, owing to absence of the let-7 gene. Using C. sulstoni as a representative let-7 -lacking species to characterize normal larval development in the absence of let-7 , we demonstrate that, except for the lack of let-7 , the heterochronic gene network is otherwise functionally conserved. We also report that species lacking let-7 contain a group of divergent let-7 orthologs -- also known as the let-7-family of microRNAs -- that have apparently assumed the role of targeting the lin-41 mRNA. Summary Statement We have identified a group of Caenorhabditis species that lack let-7a , an otherwise highly conserved and nearly ubiquitous microRNA that was previously thought to be critical to bilaterian animal development.","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2020,"id":131574,"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":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9566,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":367672,"name":"Victor Ambros","orcid":"0000-0002-5562-5345","position":1,"is_corresponding":false},{"id":585649,"name":"Charles Nelson","orcid":"0000-0002-9639-2971","position":0,"is_corresponding":true}],"reference_count":73,"raw_metadata":null,"created_at":"2026-07-18T23:16:03.875886Z","pmid":null,"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":[]}