Segment-specific muscle degeneration is triggered directly by a steroid hormone during insect metamorphosis.

J Neurobiol 2005 Feb;62(2):164-77

Institute of Neuroscience, 1254 University of Oregon, Eugene, Oregon 97403-1254, USA.

During metamorphosis of the hawkmoth, Manduca sexta, some larval muscles degenerate while others are respecified for new functions. In larvae, accessory planta retractor muscles (APRMs) are present in abdominal segments 1 to 6 (A1 to A6). APRMs serve as proleg retractors in A3 to A6 and body wall muscles in A1 and A2. At pupation, all APRMs degenerate except those in A2 and A3, which are respecified to circulate hemolymph in pupae. The motoneurons that innervate APRMs, the APRs, likewise undergo segment-specific programmed cell death (PCD), as a direct, cell-autonomous response to the prepupal peak of ecdysteroids. The segment-specific patterns of APR and APRM death differ. The present study tested the hypothesis that APRM death is a direct, cell-autonomous response to the prepupal peak of ecdysteroids. Prevention of the prepupal peak prevented APRM degeneration, and replacement of the peak by infusion of 20-hydroxyecdysone restored the correct segment-specific pattern of APRM degeneration. Surgical denervation of APRMs did not perturb their segment-specific degeneration at pupation, indicating that signals from APRs are not required for the muscles' segment-specific responses to ecdysteroids. The possibility that instructive signals originate from APRMs' epidermal attachment points was tested by treating the epidermis with a juvenile hormone analog to prevent pupal development. This manipulation likewise did not alter APRM fate. We conclude that both the muscles and motoneurons in this motor system respond directly and cell-autonomously to prepupal ecdysteroids to produce a segment-specific pattern of PCD that is matched to the functional requirements of the pupal body.

Download full-text PDF

Source
http://dx.doi.org/10.1002/neu.20077DOI Listing
February 2005
28 Reads

Publication Analysis

Top Keywords

prepupal peak
12
peak ecdysteroids
8
segment-specific pattern
8
aprm degeneration
8
degenerate respecified
8
aprm death
8
cell-autonomous response
8
direct cell-autonomous
8
response prepupal
8
segment-specific
7
aprms
5
aprm
5
correct segment-specific
4
pattern aprm
4
restored correct
4
signals aprs
4
20-hydroxyecdysone restored
4
pupation indicating
4
degeneration surgical
4
surgical denervation
4

References

(Supplied by CrossRef)
Article in Physiol Rev
Aranda et al.
Physiol Rev 2001
Article in Dev Genes Evol
Bayline et al.
Dev Genes Evol 1998
Article in Ann Entomol Soc Am
Bell et al.
Ann Entomol Soc Am 1978

Breedlove et al.
2002
Article in J Cell Sci
Caveney et al.
J Cell Sci 1969
Article in J Neurobiol
Consoulas et al.
J Neurobiol 1997
Article in J Neurosci
Consoulas et al.
J Neurosci 1998
Article in Proc Natl Acad Sci USA
Diatchenko et al.
Proc Natl Acad Sci USA 1996
Article in J Exp Biol
Dominick et al.
J Exp Biol 1984
Article in Chem Senses
Dougherty et al.
Chem Senses 2002
Article in Am Nat
Ephrussi et al.
Am Nat 1936

Similar Publications