{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T19:44:35Z","timestamp":1768506275728,"version":"3.49.0"},"posted":{"date-parts":[[2023,7,27]]},"group-title":"Developmental Biology","reference-count":52,"publisher":"openRxiv","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2023,7,27]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  The thymus is the site of T lymphocyte development and T cell education to recognize foreign, but not self, antigens. B cells also reside and develop in the thymus, although their functions are less clear. During \u2018thymic involution,\u2019 a process of lymphoid atrophy and adipose replacement linked to sexual maturation, thymocytes decline. However, thymic B cells decrease far less than T cells, such that B cells comprise \u223c1% of human neonatal thymocytes, but up to \u223c10% in adults. All jawed vertebrates possess a thymus, and we and others have shown zebrafish (\n                  <jats:italic>Danio rerio<\/jats:italic>\n                  ) also have thymic B cells. Here, we investigated the precise identities of zebrafish thymic T and B cells and how they change with involution. We assessed the timing and specific details of zebrafish thymic involution using multiple lymphocyte-specific, fluorophore-labeled transgenic lines, quantifying the changes in thymic T- and B-lymphocytes pre- vs. post-involution. Our results prove that, as in humans, zebrafish thymic B cells increase relative to T cells post-involution. We also performed RNA sequencing (RNA-seq) on\n                  <jats:italic>D. rerio<\/jats:italic>\n                  thymic and marrow lymphocytes of four novel double-transgenic lines, identifying distinct populations of immature T and B cells. Collectively, this is the first comprehensive analysis of zebrafish thymic involution, demonstrating its similarity to human involution, and establishing the highly genetically- manipulatable zebrafish model as a template for involution studies.\n                <\/jats:p>","DOI":"10.1101\/2023.07.25.550519","type":"posted-content","created":{"date-parts":[[2023,7,27]],"date-time":"2023-07-27T17:05:34Z","timestamp":1690477534000},"source":"Crossref","is-referenced-by-count":0,"title":["Dynamic Changes in Lymphocyte Populations Establish Zebrafish as a Thymic Involution Model"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-8593-4835","authenticated-orcid":false,"given":"Ameera","family":"Hasan","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jose J.","family":"Macias","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Brash\u00e9","family":"Wood","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Megan","family":"Malone-Perez","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gilseung","family":"Park","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Clay A.","family":"Foster","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2936-2817","authenticated-orcid":false,"given":"J. 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