Baia Amaral, D. | bioRxiv Science

bioRxiv2026

Spatio-temporally regulated maternal RNA decay factor essential for zebrafish development

Maternal mRNA decay is essential for the Maternal-to-Zygotic Transition (MZT), yet its impact on spatial regulation has remained largely unexplored. We identify Cth1 as the first maternally encoded RNA-decay factor regulated in a spatiotemporal manner outside the germline in zebrafish, driven by conserved 3'UTR cis-elements. RfxCas13-dmediated depletion of maternal cth1 revealed early developmental defects that could not be assessed with SpyCas9 mutants due to infertility from impaired gametogenesis. Mechanistically, Cth1 acts independently of zygotic genome activation, recognizing AUrich motifs in maternal 3'UTRs to promote deadenylation and decay in a spatio-temporal manner; deletion of these motifs or depletion of Cth1 stabilizes both reporter and endogenous transcripts. These findings establish Cth1 as a key component of the maternal program and provide the first direct evidence that spatio-temporally regulated mRNA decay, outside the germline, contributes to early vertebrate development.

developmental biology↗

bioRxiv2018

Deep evolutionary origin of limb and fin regeneration

Salamanders and lungfishes are the only sarcopterygians (lobe-finned vertebrates) capable of complete limb and paired fin regeneration, respectively. Among actinopterygians (ray-finned fishes), regeneration after amputation at the fin endoskeleton has only been demonstrated in Polypterid fishes (Cladistia). Whether complete appendage regeneration in sarcopterygians and actinopterygians evolved independently or has a common origin remains unknown. Here we combine fin regeneration assays and comparative RNA-seq analysis to provide support for a common origin of a paired appendage regeneration in osteichthyes (bony vertebrates). We show that, in addition to Polypterids, regeneration after fin endoskeleton amputation occurs in extant representatives of all major actinopterygian clades: the American paddlefish, (Chondrostei), the spotted gar (Holostei), as well as in two cichlid species, the white convict and the oscar (Teleostei). Our comparative RNA-seq analysis of regenerating blastemas of axolotl and Polypterus reveals the activation of common genetic pathways and expression profiles, consistent with a pan-osteichthyes genetic program of appendage regeneration. Collectively, our findings support a deep evolutionary origin of paired appendage regeneration in osteichthyes and provide an evolutionary framework for studies on the genetic basis of appendage regeneration.

evolutionary biology↗