Organization of the larval pre-ecdysis motor pattern in the tobacco hornworm,Manduca sexta |
| |
Authors: | A Novicki J C Weeks |
| |
Institution: | (1) Institute of Neuroscience, University of Oregon, 97403 Eugene, OR, USA |
| |
Abstract: | The tobacco hornworm, Manduca sexta, undergoes several larval molts before transforming into a pupa and then an adult moth. Each molt culminates in ecdysis, when the old cuticle is shed. Prior to each larval ecdysis, the old cuticle is loosened by pre-ecdysis behavior, which consists of rhythmic compressions that are synchronous along the abdomen and on both body sides, and rhythmic retractions of the abdominal prolegs. Both pre-ecdysis and ecdysis behaviors are triggered by a peptide, eclosion hormone. The aim of the present study was to investigate the neural circuitry underlying larval preecdysis behavior. The pre-ecdysis motor pattern was recorded in isolated nerve cords from eclosion hormone-treated larvae, and the effects of connective transections and ionic manipulations were tested. Our results suggest that the larval pre-ecdysis compression motor pattern is coordinated and maintained by interneurons in the terminal abdominal ganglion that ascend the nerve cord without chemical synaptic relays; these interneurons make bilateral, probably monosynaptic, excitatory connections with identified pre-ecdysis motor neurons throughout the abdominal nerve cord. This model of the organization of the larval pre-ecdysis motor pattern should facilitate identification of the relevant interneurons, allowing future investigation of the neural basis of the developmental weakening of the pre-ecdysis motor pattern that accompanies the larval-pupal transformation.Abbreviations A3, A4...
abdominal ganglia 3, 4...
- AT
terminal abdominal ganglion
- ALE
anterior lateral external muscle
- DN
dorsal nerve
- DNA
anterior branch of the dorsal nerve
- DNL
lateral branch of the dorsal nerve
- DNP
posterior branch of the dorsal nerve
- EH
eclosion hormone
- TP
tergopleural muscle
- VN
ventral nerve
- VNA
anterior branch of the ventral nerve
- VNL
lateral branch of the ventral nerve
- VNP
posterior branch of the ventral nerve |
| |
Keywords: | Central pattern generator Eclosion hormone Molting Moth |
本文献已被 SpringerLink 等数据库收录! |
|