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Abstract Many species in the tunicate family Molgulidae have independently lost their swimming larval form and instead develop as tailless, immotile larvae. These larvae do not develop structures that are essential for swimming such as the notochord, otolith, and tail muscles. However, little is known about neural development in these nonswimming larvae. Here, we studied the patterning of the Motor Ganglion (MG) ofMolgula occulta, a nonswimming species. We found that spatial patterns of MG neuron regulators in this species are conserved, compared with species with swimming larvae, suggesting that the gene networks regulating their expression are intact despite the loss of swimming. However, expression of the key motor neuron regulatory geneEbf (Collier/Olf/EBF)was reduced in the developing MG ofM. occultawhen compared with molgulid species with swimming larvae. This was corroborated by measuring allele‐specific expression ofEbfin hybrid embryos from crosses ofM. occultawith the swimming speciesM. oculata. Heterologous reporter construct assays in the model tunicate speciesCiona robustarevealed a specificcis‐regulatory sequence change that reduces expression ofEbfin the MG, but not in other cells. Taken together, these data suggest that MG neurons are still specified inM. occultalarvae, but their differentiation might be impaired due to reduction ofEbfexpression levels.
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This content will become publicly available on May 1, 2025
Development and circuitry of the tunicate larval Motor Ganglion, a putative hindbrain/spinal cord homolog
Abstract The Motor Ganglion (MG) is a small collection of neurons that control the swimming movements of the tunicate tadpole larva. Situated at the base of the tail, molecular and functional comparisons suggest that may be a homolog of the spinal cord and/or hindbrain (“rhombospinal” region) of vertebrates. Here we review the most current knowledge of the development, connectivity, functions, and unique identities of the neurons that comprise the MG, drawn mostly from studies inCionaspp. The simple cell lineages, minimal cellular composition, and comprehensively mapped “connectome” of theCionaMG all make this an excellent model for studying the development and physiology of motor control in aquatic larvae.
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- Award ID(s):
- 1940743
- PAR ID:
- 10533967
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Journal of Experimental Zoology Part B: Molecular and Developmental Evolution
- Volume:
- 342
- Issue:
- 3
- ISSN:
- 1552-5007
- Page Range / eLocation ID:
- 200 to 211
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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