The Development of Three Identified Motor Neurons in the Larva of an Ascidian, Halocynthia roretzi
| Autor: | Toshiaki Okada, You Katsuyama, Fumihito Ono, Yasushi Okamura |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Male
swimming behavior Embryo Nonmammalian Potassium Channels ascidian Recombinant Fusion Proteins dominant negative LIM homeodomain protein Green Fluorescent Proteins Population Central nervous system Biology tadpole larva Gene expression medicine Animals Myocyte Urochordata education Molecular Biology neural tube In Situ Hybridization Swimming Homeodomain Proteins Motor Neurons education.field_of_study Microscopy Confocal Neural tube Gene Expression Regulation Developmental Dendrites Anatomy Cell Biology Motor neuron Cell biology Luminescent Proteins medicine.anatomical_structure nervous system Larva ion channel Homeobox Female Ectopic expression Ion Channel Gating Developmental Biology |
| Zdroj: | Developmental Biology. 244(2):278-292 |
| ISSN: | 0012-1606 |
| DOI: | 10.1006/dbio.2002.0585 |
| Popis: | The generation of distinct classes of motor neurons underlies the development of complex motile behavior in all animals and is well characterized in chordates. Recent molecular studies indicate that the ascidian larval central nervous system (CNS) exhibits anteroposterior regionalization similar to that seen in the vertebrate CNS. To extend the understanding about the diversity of motor neurons in the ascidian larva, we have identified the number, position, and projection of individual motor neurons in Halocynthia roretzi, using a green fluorescent protein under the control of a neuron-specific promoter. Three pairs of motor neurons, each with a distinct shape and innervation pattern, were identified along the anteroposterior axis of the neural tube: the anterior and posterior pairs extend their axons toward dorsal muscle cells, whereas the middle pair project their axons toward ventral muscle. Overexpression of a dominant-negative form of a potassium channel in these cells resulted in paralysis on the injected side, thus these cells must constitute the major population of motor neurons responsible for swimming behavior. Lim class homeobox genes have been known as candidate genes that determine subtypes of motor neurons. Therefore, the expression pattern of Hrlim, which is a Lim class homeobox gene, was examined in the motor neuron precursors. All three motor neurons expressed Hrlim at the tailbud stage, although each down-regulated Hrlim at a different time. Misexpression of Hrlim in the epidermal lineage led to ectopic expression of TuNa2, a putative voltage-gated channel gene normally expressed predominantly in the three pairs of motor neurons. Hrlim may control membrane excitability of motor neurons by regulating ion channel gene expression. |
| Databáze: | OpenAIRE |
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