Project description:Evolution of the capacity to form secondary outgrowths from the principal embryonic axes was a crucial innovation that potentiated the diversification of animal body plans. Nevertheless, precisely how such outgrowths develop in early-branching metazoan species remains poorly understood. To identify genes potentially involved in tentacle initiation, outgrowth, and maintenance, we performed transcriptional profiling at three different stages of Nematostella development: late planula larvae with tentacle buds, animals with growing tentacles, and mature animals with four-tentacle polyps. At each of these three stages, the animal was bisected such that the oral tentacle portion (head) could be compared to the body column.
Project description:Evolution of the capacity to form secondary outgrowths from the principal embryonic axes was a crucial innovation that potentiated the diversification of animal body plans. Nevertheless, precisely how such outgrowths develop in early-branching metazoan species remains poorly understood. To identify genes potentially involved in tentacle initiation, outgrowth, and maintenance, we performed transcriptional profiling at three different stages of Nematostella development: late planula larvae with tentacle buds, animals with growing tentacles, and mature animals with four-tentacle polyps. At each of these three stages, the animal was bisected such that the oral tentacle portion (head) could be compared to the body column. Tentacle buds, growing tentacles, and mature tentacles, were compared to body columns from each matching stage in duplicate, for a total of 6 samples.
Project description:The basic helix-loop helix transcription factor Twist plays diverse roles in mesodermal development across bilaterians, but its function in cnidarians remains unclear. Here, we investigate the role of Twist in tentacle morphogenesis and tissue homeostasis in the sea anemone Nematostella vectensis. Using a CRISPR/Cas9 generated knockout, we show that twist mutants exhibit impaired secondary tentacle formation, reduced proliferation in budding tentacles, and absence of micronemes, structures that demarcate tentacle boundaries-suggesting defects in spatial patterning. We demonstrate that twist expression is regulated by Wnt, BMP, and Notch signalling but is independent of MAPK and Hedgehog pathways. Loss of Twist disrupts expression of mesodermal transcription factors paraxis and tbx15 and perturbs the TOR-FGF signalling feedback loop necessary for normal tentacle growth. Moreover, starting at juveniles, mutants develop neoplasm-like epithelial overgrowth with tentacle-like molecular and morphological profiles, indicating a role for Twist in maintaining tissue homeostasis at the oral pole. Together, our findings reveal that Twist integrates major signalling pathways to regulate secondary tentacle patterning and maintain spatial tissue organisation in the diploblastic Nematostella vectensis.
Project description:2 anemone species were sequenced to determine tissue-specific differential expression and to find toxin composition in the two sea anemones
