The trunk is a key feature of the bilaterian body plan. Despite spectacular morphological diversity in bilaterian trunk anatomies, most insights into trunk development are from segmented taxa, namely arthropods and chordates. Mechanisms of posterior axis elongation (PAE) and segmentation are tightly coupled in arthropods and vertebrates, making it challenging to differentiate between the underlying developmental mechanisms specific to each process. Investigating trunk elongation in unsegmented animals facilitates examination of mechanisms specific to PAE and provides a different perspective for testing hypotheses of bilaterian trunk evolution. Here we investigate the developmental roles of canonical Wnt and Notch signaling in the hemichordate
Wnt genes code for ligands that activate signaling pathways during development in Metazoa. Through the canonical Wnt (cWnt) signaling pathway, these genes regulate important processes in bilaterian development, such as establishing the anteroposterior axis and posterior growth. In Arthropoda, Wnt ligands also regulate segment polarity, and outgrowth and patterning of developing appendages. Arthropods are part of a lineage called Panarthropoda that includes Onychophora and Tardigrada. Previous studies revealed potential roles of Wnt genes in regulating posterior growth, segment polarity, and growth and patterning of legs in Onychophora. Unlike most other panarthropods, tardigrades lack posterior growth, but retain segmentation and appendages. Here, we investigated Wnt genes in tardigrades to gain insight into potential roles that these genes play during development of the highly compact and miniaturized tardigrade body plan.
We analyzed published genomes for two representatives of Tardigrada,
Our results indicate that Wnt signaling has been highly modified in Tardigrada. While most components of cWnt signaling are conserved in tardigrades, we conclude that tardigrades have lost
- Award ID(s):
- 1951257
- Publication Date:
- NSF-PAR ID:
- 10361112
- Journal Name:
- BMC Ecology and Evolution
- Volume:
- 21
- Issue:
- 1
- ISSN:
- 2730-7182
- Publisher:
- Springer Science + Business Media
- Sponsoring Org:
- National Science Foundation
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