scholarly journals Inactivation of the Corpora Allata in the Final Instar of the Tobacco Hornworm,Manduca sexta, Requires Integrity of Certain Neural Pathways from the Brain

1989 ◽  
Vol 177 (3) ◽  
pp. 396-400 ◽  
Author(s):  
LOUIS SAFRANEK ◽  
CARROLL M. WILLIAMS
Keyword(s):  
Manduca Sexta ◽  
Tobacco Hornworm ◽  
Corpora Allata ◽  
Neural Pathways ◽  
The Brain

Control of Moulting and Metamorphosis in the Tobacco Hornworm, Manduca Sexta (L.): Cessation of Juvenile Hormone Secretion as a Trigger for Pupation

1974 ◽  
Vol 61 (2) ◽  
pp. 493-501 ◽  
Author(s):  
H. FREDERIK NIJHOUT ◽  
CARROLL M. WILLIAMS
Keyword(s):  
Juvenile Hormone ◽  
Manduca Sexta ◽  
Larval Instar ◽  
Hormone Secretion ◽  
Tobacco Hornworm ◽  
Corpora Allata ◽  
Functional Failure ◽  
Prothoracicotropic Hormone ◽  
The Brain

During the final larval instar of the tobacco hornworm the presence of juvenile hormone (JH) inhibits the secretion of the brain's prothoracicotropic hormone (PTTH). The corpora allata cease to secrete JH when the larvae attain a weight of approximately 5 g. The JH is cleared from the haemolymph in about 24 h. This process in itself renders the brain competent to release PTTH. The actual release of PTTH occurs at the very first photo-periodic gate after the JH has disappeared from the haemolymph. A functional failure of this normal mechanism is apparently responsible for the developmental standstill of Lepidoptera which diapause as mature larvae.

Polyamines Differentially Inhibit Cyclic AMP-Dependent Protein Kinase-Mediated Phosphorylation in the Brain of the Tobacco Hornworm, Manduca sexta

1988 ◽  
Vol 51 (5) ◽  
pp. 1581-1591 ◽  
Author(s):  
Wendell L. Combest ◽  
Timothy J. Bloom ◽  
Lawrence I. Gilbert
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Manduca Sexta ◽  
Tobacco Hornworm ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
The Brain

Immunohistochemical investigations of neuropeptides in the brain, corpora cardiaca, and corpora allata of an adult lepidopteran insect, Manduca sexta (L)

1983 ◽  
Vol 232 (2) ◽  
pp. 295-317 ◽  
Author(s):  
M. El-Salhy ◽  
S. Falkmer ◽  
K. J. Kramer ◽  
R. D. Speirs
Keyword(s):  
Manduca Sexta ◽  
Corpora Allata ◽  
Corpora Cardiaca ◽  
Lepidopteran Insect ◽  
The Brain

scholarly journals Developmental endocrinology of larval moulting in the tobacco hornworm, Manduca sexta

1987 ◽  
Vol 128 (1) ◽  
pp. 175-192
Author(s):  
W. E. Bollenbacher ◽  
N. A. Granger ◽  
E. J. Katahira ◽  
M. A. O'Brien
Keyword(s):  
Manduca Sexta ◽  
Cumulative Effect ◽  
Peptide Hormone ◽  
Tobacco Hornworm ◽  
Corpora Allata ◽  
Indirect Measure ◽  
Prothoracic Glands ◽  
Single Burst ◽  
Larval Moult

A larval moult in the tobacco hornworm, Manduca sexta, involves an endocrine cascade that begins with the release of a cerebral peptide hormone, the prothoracicotropic hormone (PTTH). The release of PTTH is gated, occurs during the scotophase and appears to be developmentally cued. In fourth instar Manduca larvae, PTTH release into the haemolymph occurs as a single burst over a few hours during the head critical period, i.e. the time during which the head (brain) is needed for the initiation of the moult to the fifth (last) instar. Released PTTH activates the prothoracic glands (PGs), and within a few hours the cumulative effect of this event results in a dramatic increase in the haemolymph ecdysteroid titre, which then elicits the moult. An assessment of the capacity of the corpora allata (CA) to synthesize juvenile hormone (JH) in vitro indicates that the above sequence of endocrine events begins only when JH synthesis has reached a nadir for the instar. Since CA activity is an indirect measure of the haemolymph titre of the hormone, it is conceivable that the developmentally cued release of PTTH is permissively controlled by a decreasing haemolymph titre of JH. With the increase in the ecdysteroid titre which marks the end of this endocrine cascade, the CA again become active, presumably to cause the increase in the JH haemolymph titre which directs the larval moult. This investigation has thus established the temporal and quantitative dynamics of the PTTH-PG axis that drive larval moulting and provides insight into the interendocrine regulatory relationships that may exist between the ecdysteroids and JHs. These possible relationships and the role of the brain in their regulation are discussed.

Control of Cuticle Extensibility in the Wings of Adult Manduca At the Time of Eclosion: Effects of Eclosion Hormone and Bursicon

1977 ◽  
Vol 70 (1) ◽  
pp. 27-39
Author(s):  
STUART E. REYNOLDS
Keyword(s):  
Manduca Sexta ◽  
Nerve Cord ◽  
Gel Filtration ◽  
Corpora Allata ◽  
Partial Purification ◽  
Active Principle ◽  
Eclosion Hormone ◽  
Highly Sensitive ◽  
The Brain ◽  
Pharate Adult

The wings of pharate adult tobacco hornworm moths, Manduca sexta, are relatively inextensible until 3 or 4 h before emergence from the pupal case. At this time the wing cuticle becomes plasticized, so that by the time of eclosion, the wings are readily extensible. This change in the mechanical properties of the wing cuticle is shown to be under the control of a factor from the head. This factor is present in the corpora cardiaca/corpora allata complex, and in the protocerebrum of the brain, being released into the blood prior to eclosion. It is able to act directly on isolated wings. The active principle was found to be indistinguishable in a number of ways from the hormone which triggers emergence from the pupal case, the eclosion hormone. Partial purification of the eclosion hormone failed to separate activity causing eclosion from activity causing wing cuticle plasticization. It is concluded that the same hormone is probably responsible for both effects. The cuticle plasticizing activity of the eclosion hormone forms the basis for a new, highly sensitive bioassay. Another factor, distinct from the eclosion hormone, is able to cause wing cuticle plasticization. This factor is found in the abdominal nerve cord, and is only released into the blood after eclosion has occurred. It is probably identical with the tanning hormone, bursicon, which is released at this time. The factor in the nerve cord which causes cuticle plasticization is indistinguishable from bursicon in a number of ways, including partial purification by gel filtration. Bursicon evidently causes a further increase in wing cuticle extensibility after eclosion, at the time of wing inflation.

The brain adenylate cyclase system of the tobacco hornworm, Manduca sexta

1985 ◽  
Vol 15 (5) ◽  
pp. 579-588 ◽  
Author(s):  
Wendell L. Combest ◽  
David Sheridan ◽  
Lawrence I. Gilbert
Keyword(s):  
Adenylate Cyclase ◽  
Manduca Sexta ◽  
Tobacco Hornworm ◽  
Adenylate Cyclase System ◽  
The Brain

Ultrastructure of the neurosecretory cells in the brain of diapausing pupae of the tobacco hornworm, Manduca sexta (l)

1977 ◽  
Vol 9 (3) ◽  
pp. 567-574 ◽  
Author(s):  
Thomas K. Borg ◽  
Robert A. Bell
Keyword(s):  
Manduca Sexta ◽  
Tobacco Hornworm ◽  
Neurosecretory Cells ◽  
The Brain

scholarly journals Farnesol and farnesal dehydrogenase(s) in corpora allata of the tobacco hornworm moth, Manduca sexta.

1983 ◽  
Vol 24 (12) ◽  
pp. 1586-1594
Author(s):  
F C Baker ◽  
B Mauchamp ◽  
L W Tsai ◽  
D A Schooley
Keyword(s):  
Manduca Sexta ◽  
Tobacco Hornworm ◽  
Corpora Allata
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