| First Author | Onimaru K | Year | 2021 |
| Journal | Elife | Volume | 10 |
| PubMed ID | 33560225 | Mgi Jnum | J:303813 |
| Mgi Id | MGI:6510995 | Doi | 10.7554/eLife.62865 |
| Citation | Onimaru K, et al. (2021) Developmental hourglass and heterochronic shifts in fin and limb development. Elife 10:e62865 |
| abstractText | How genetic changes are linked to morphological novelties and developmental constraints remains elusive. Here, we investigate genetic apparatuses that distinguish fish fins from tetrapod limbs by analyzing transcriptomes and open-chromatin regions (OCRs). Specifically, we compared mouse forelimb buds with the pectoral fin buds of an elasmobranch, the brown-banded bamboo shark (Chiloscyllium punctatum). A transcriptomic comparison with an accurate orthology map revealed both a mass heterochrony and hourglass-shaped conservation of gene expression between fins and limbs. Furthermore, open-chromatin analysis suggested that access to conserved regulatory sequences is transiently increased during mid-stage limb development. During this stage, stage-specific and tissue-specific OCRs were also enriched. Together, early and late stages of fin/limb development are more permissive to mutations than middle stages, which may have contributed to major morphological changes during the fin-to-limb evolution. We hypothesize that the middle stages are constrained by regulatory complexity that results from dynamic and tissue-specific transcriptional controls. |
