Physiology of Insect Rhythms

1974 ◽  
Vol 60 (2) ◽  
pp. 371-382 ◽  
Author(s):  
JAMES W. TRUMAN ◽  
LYNN M. RIDDIFORD
Keyword(s):  
Developmental Stage ◽  
Manduca Sexta ◽  
Prothoracic Gland ◽  
Dorsal Midline ◽  
Prothoracic Glands ◽  
The Times ◽  
Manduca Sexta Larvae ◽  
The Brain ◽  
Pink Pigment ◽  
Stimulation Of

1. Late in the fifth instar, Manduca sexta larvae cease feeding and become ‘wandering larvae’ which are morphologically characterized by an ‘exposed heart’ and the appearance of a pink pigment along the dorsal midline. Two days later ocellar retraction signals the beginning of the prepupal period and 3 days thereafter the pupal ecdysis occurs. 2. The timing of the endocrine events which are responsible for these changes was determined by ligaturing animals of the appropriate developmental stage at various times of day. The times of prothoracicotropic hormone (PTTH) release by the brain were determined by neck ligations. Estimates of the times of prothoracic gland activity were obtained through the isolation of abdomens. 3. It was found that the fifth stage larva releases PTTH on two occasions. The first release lasts approximately 3.5 h and triggers the transformation to the wandering stage. The second release occurs two days later, lasts at least 7 h, and provokes the onset of the pupal moult. 4. The prothoracic glands are involved in triggering the same two changes. In the first instance the glands apparently require the continuing influence of the brain and consequently secrete for about 3.5 h. During the stimulation of the pupal moult the prothoracic glands become ‘turned-on’ and continue to secrete for at least 10 h after the time when the brain is no longer required. In this latter instance the total time of prothoracic gland activity may be as long as 17 h.

Gap junctions in the prothoracic glands of the tobacco hornworm, Manduca sexta

1992 ◽  
Vol 50 (1) ◽  
pp. 706-707
Author(s):  
Ji-da Dai ◽  
M. Joseph Costello ◽  
Lawrence I. Gilbert
Keyword(s):  
Gap Junctions ◽  
Small Molecules ◽  
Manduca Sexta ◽  
Freeze Fracture ◽  
Cell Communication ◽  
Cellular Level ◽  
Thin Sections ◽  
Prothoracic Glands ◽  
Polyhydroxylated Steroids ◽  
Stimulation Of

Insect molting and metamorphosis are elicited by a class of polyhydroxylated steroids, ecdysteroids, that originate in the prothoracic glands (PGs). Prothoracicotropic hormone stimulation of steroidogenesis by the PGs at the cellular level involves both calcium and cAMP. Cell-to-cell communication mediated by gap junctions may play a key role in regulating signal transduction by controlling the transmission of small molecules and ions between adjacent cells. This is the first report of gap junctions in the PGs, the evidence obtained by means of SEM, thin sections and freeze-fracture replicas.

Spermine stimulation of phosphoprotein dephosphorylation in the brain of Manduca sexta

1990 ◽  
Vol 20 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Timothy J. Bloom ◽  
Wendell L. Combest ◽  
Lawrence I. Gilbert
Keyword(s):  
Manduca Sexta ◽  
The Brain ◽  
Stimulation Of

HORMONES AND THE TERMINATION AND REINDUCTION OF DIAPAUSE IN CEPHUS CINCTUS NORT. (HYMENOPTERA: CEPHIDAE)

1955 ◽  
Vol 33 (5) ◽  
pp. 339-369 ◽  
Author(s):  
Norman Stanley Church
Keyword(s):  
Heat Treatment ◽  
Neurosecretory Cells ◽  
Prothoracic Gland ◽  
Cytological Examination ◽  
Cephus Cinctus ◽  
Environmental Stimuli ◽  
Prothoracic Glands ◽  
The Brain

Ligation and parabiosis experiments and cytological studies showed postdiapause morphogenesis in Cephus cinctus larvae to be initiated by a growth and differentiation hormone from the prothoracic glands. The prothoracic glands in turn are probably stimulated by a hormone from the protocerebral neurosecretory cells. The brain continues to influence the prothoracic glands even after they have begun to secrete and the influence is more than that of a simple stimulation by the neurohormone. Furthermore, experiments with larvae reared apart from their cocoons suggested that the brain is to some extent influenced by environmental stimuli. If an effective amount of growth and differentiation hormone has not yet been secreted, exposure of a week or less at 35 °C. causes postdiapause C. cinctus larvae to revert to diapause. Forty degrees has a much weaker effect. Cytological examination suggested that 35 °C. halts prothoracic gland activity and, meanwhile, permits the neurohormone to be dissipated. At the end of the heat treatment there is insufficient neurohormone left to reactivate the prothoracic glands, which revert to dormancy.

scholarly journals In Vitro Studies on the Role of the Brain and Prothoracic Glands in the Pupal Diapause of Manduca Sexta

1984 ◽  
Vol 108 (1) ◽  
pp. 9-24 ◽  
Author(s):  
M. F. BOWEN ◽  
W. E. BOLLENBACHER ◽  
L. I. GILBERT
Keyword(s):  
Manduca Sexta ◽  
Biosynthetic Activity ◽  
Virtual Absence ◽  
Prothoracic Glands ◽  
Pupal Diapause ◽  
Radio Immunoassay ◽  
Moulting Hormone ◽  
The Brain

Pupal diapause in the tobacco horn worm, Manduca sexta (Johannson), is characterized by the absence of an increased ecdysteroid titre in the haemolymph during the first week of pupal life as measured by radio-immunoassay. This virtual absence of the steroid moulting hormone is thought to be responsible for the diapause state and it is apparently a consequence of the failure of the diapausing pupal prothoracic glands (PG) to synthesize ecdysone at an increased rate. In Manduca, this apparent failure of PG activation during diapause may be in response to two endo-crinological circumstances: the curtailment of PTTH release as opposed to its synthesis and transport, and the development of refractoriness of the gland to stimulation by PTTH. The former was examined by measuring PTTH activity present in brains and brain-retrocerebral complexes of diapausing and non-diapausing pupae and the latter by assessing PG biosynthetic activity in vitro in the presence and absence of PTTH.

Neuromodulation by 5-hydroxytryptamine in the antennal lobe of the sphinx moth Manduca sexta.

1995 ◽  
Vol 198 (3) ◽  
pp. 603-611 ◽  
Author(s):  
P Kloppenburg ◽  
J G Hildebrand
Keyword(s):  
Electrical Stimulation ◽  
Manduca Sexta ◽  
Antennal Lobe ◽  
Input Resistance ◽  
High Concentration ◽  
Cell Excitability ◽  
Excitatory Responses ◽  
The Brain ◽  
Antennal Nerve ◽  
Stimulation Of

Using intracellular recording techniques, we have begun to examine the effects of 5-hydroxytryptamine (5-HT) on antennal-lobe (AL) neurones in the brain of the adult moth Manduca sexta. 5-HT modulated the responses of local interneurones and projection neurones, which were recognized on the basis of well-established electrophysiological criteria, to primary synaptic input elicited by electrical stimulation of the ipsilateral antennal nerve. 5-HT applied at low concentration (10(-8) mol l-1) reduced the excitatory responses evoked by electrical stimulation of the antennal nerve, whereas at high concentration (10(-4) mol l-1), 5-HT enhanced the responses. At 10(-4) mol l1, 5-HT increased cell input resistance, led to broadening of action potentials and caused increased cell excitability in many AL neurones.

Co-localization of ecdysteroid receptors and c-fos-like protein in the brain of Manduca sexta larvae

1991 ◽  
Vol 200 (3) ◽  
pp. 149-155 ◽  
Author(s):  
Hans-J�rgen Bidmon ◽  
Noelle Audrey Granger ◽  
Walter Erich Stumpf
Keyword(s):  
Manduca Sexta ◽  
Manduca Sexta Larvae ◽  
The Brain ◽  
Ecdysteroid Receptors

scholarly journals Cellular changes in the prothoracic glands of diapausing pupae of Manduca sexta

1986 ◽  
Vol 120 (1) ◽  
pp. 131-142
Author(s):  
W. A. Smith ◽  
M. F. Bowen ◽  
W. E. Bollenbacher ◽  
L. I. Gilbert
Keyword(s):  
Manduca Sexta ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Adenylate Cyclase System ◽  
Cellular Changes ◽  
Prothoracic Glands ◽  
The Brain ◽  
Camp Formation

Prothoracic glands from diapausing pupae of the tobacco hornworm, Manduca sexta, synthesize markedly less ecdysone in vitro in response to prothoracicotropic hormone (PTTH) than do glands from non-diapausing pupae. Impaired steroidogenesis is also observed in glands from diapausing animals exposed to agents that enhance ecdysone synthesis in non-diapausing pupal glands by increasing intracellular levels of cAMP (1-methyl-3-isobutylxanthine, dibutyryl cAMP, and the calcium ionophore A23187). In contrast, prothoracic glands from diapausing pupae synthesize significantly more cAMP in response to PTTH and A23187 than do those from non-diapausing pupae. These observations indicate that the PTTH-refractoriness characteristic of prothoracic glands during diapause results from a lesion in the steroidogenic pathway occurring beyond the level of the PTTH receptor-adenylate cyclase system. The diapause condition of the prothoracic glands (reduced ecdysone synthesis accompanied by enhanced cAMP formation) can be mimicked by extirpation of the brain of a non-diapausing pupa. Thus, cellular changes in the prothoracic glands associated with diapause may arise as a result of the absence of some factor produced by the pupal brain (e.g. PTTH).

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