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Octopod, a homeotic mutation of the moth Manduca sexta, affects development of both mesodermal and ectodermal
1Section of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853-2702.
Developmental Biology
|January 1, 1993
Summary
The Octopod mutation in Manduca sexta causes abdominal segments to develop thoracic-like legs. Leg development in these homeotic legs is guided by differentiation centers, similar to normal legs, and muscle degeneration is intrinsic, not neuron-dependent.
Area of Science:
- Developmental biology
- Genetics
- Insect morphology
Background:
- The homeotic mutation Octopod (Octo) in Manduca sexta transforms abdominal segment A1 into a thoracic-like segment (T3).
- Normal thoracic legs develop from differentiation centers at specific joints during metamorphosis.
- Understanding leg development is crucial for comprehending pattern formation and segment identity.
Purpose of the Study:
- To investigate leg development in the Octopod mutant of Manduca sexta.
- To determine the role of differentiation centers in homeotic leg formation.
- To examine the development and innervation of muscles in homeotic legs.
Main Methods:
- Analysis of the homeotic mutation Octopod (Octo) in Manduca sexta.
- Microscopic examination of larval and adult homeotic legs.
- Observation of differentiation centers and muscle development.
- Investigation of motoneuron innervation and muscle degeneration patterns.
Main Results:
- Homeotic legs in Octopod mutants exhibit differentiation centers analogous to those in normal thoracic legs.
- The number of segments in adult homeotic legs correlates with larval differentiation centers.
- Homeotic larval muscles possess thoracic identities and degenerate independently of their common innervation.
- Muscle degeneration timing indicates intrinsic developmental fates, not neuron-dictated schedules.
Conclusions:
- Differentiation centers are key organizers for both normal and homeotic leg segment formation.
- Homeotic leg development recapitulates aspects of thoracic leg development.
- Muscle developmental fate is intrinsic and not solely determined by neuronal input.
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