Haemolymph ecdysteroid titres during larval-adult development in Rhodnius prolixus: Correlations with moulting hormone action and brain neurosecretory cell activity

1982 ◽  
Vol 28 (6) ◽  
pp. 519-525 ◽  
Author(s):  
C.G.H. Steel ◽  
W.E. Bollenbacher ◽  
S.L. Smith ◽  
L.I. Gilbert
Keyword(s):  
Adult Development ◽  
Neurosecretory Cell ◽  
Cell Activity ◽  
Rhodnius Prolixus ◽  
Hormone Action ◽  
Moulting Hormone

BIOCHEMICAL MECHANISMS OF HORMONE ACTION

1966 ◽  
Vol 53 (3) ◽  
pp. 505-518 ◽  
Author(s):  
P. Karlson ◽  
C. E. Sekeris
Keyword(s):  
Mode Of Action ◽  
Messenger Rna ◽  
Gene Activation ◽  
Enzyme Synthesis ◽  
Active Enzyme ◽  
Hormone Action ◽  
Reaction Sequence ◽  
Allosteric Effectors ◽  
Biochemical Mechanisms ◽  
Moulting Hormone

ABSTRACT Some recent hypotheses on the mode of action of hormones are reviewed. One concept, arising from experiments with artificially cleaved ribonuclease, namely that hormones may »complete« some proteins to form an active enzyme, is regarded as unlikely. Moreover, the idea that hormones act as »allosteric effectors« of enzymes is not well substantiated. A third hypothesis, i. e. that hormones may act as gene activators, is discussed at some length. Gene activation would lead to production of messenger-RNA and induced enzyme synthesis. For ecdysone, the moulting hormone of insects, every step of this reaction sequence has been demonstrated experimentally.

An Autoradiographic Study of Neurosecretory Cell Activity of Allatectomized Females of the Grasshopper, Melanoplus sanguinipes (Fab.)

1975 ◽  
Vol 30 (7-8) ◽  
pp. 511-515
Author(s):  
G. S. Dogra
Keyword(s):  
Neurosecretory Cell ◽  
Cell Activity ◽  
Secretory Activity ◽  
Autoradiographic Study ◽  
Neurosecretory Cells ◽  
Corpus Allatum ◽  
High Uptake ◽  
Melanoplus Sanguinipes ◽  
Gradual Accumulation ◽  
Activity Cycles

Abstract Neurosecretory cell activity was studied autoradiographically in the allatectomized females of Melanoplus sanguinipes on every alternate day and in the normal control females on every fourth day for a period of 34 days. Experimental females exhibited five activity cycles against the two recorded by the control females. There was a comparatively high uptake of [3H] cystine by the neurosecretory cells of the experimental females on a particular day. During the first 12 days there was no accumulation of stainable colloid in their system. By the 24th day there was a slow and gradual accumulation of the colloids in the cells and their tracts so that on 34th day the system was well loaded with these colloids. In control females there was good accumulation of the stainable material during the first 12 days and then it declined so that 20 day old females had very little material in their system. This was followed by a massive accumulation of the stained colloids by 32nd day. The uptake of [3H] uridine was very high in the nerve-regenerate of the experimental females, and there were six cycles of secretory activity during the period of experimentation. The corpus allatum of control females, like their neurosecretory cells, exhibited only two activity cycles. Since the activity of the neurosecretory cells parallels the RNA synthesis in the nerve-regenerate, it is postulated that the neurosecretory cells produce factors for nerve-regeneration. On the basis of high uptake of isotopes by the neurosecretory cells of those allatectomized females in which the oocytes were mature it is suggested that the hormone (s) produced by the neurosecretory cells are perhaps responsible for oocyte maturation in these allatectomized females.

scholarly journals The Thoracic Gland in Rhodnius Prolixus (Hemiptera) and Its Role in Moulting

1952 ◽  
Vol 29 (4) ◽  
pp. 561-570
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
Critical Period ◽  
Fat Body ◽  
Secretory Activity ◽  
Rhodnius Prolixus ◽  
Diffuse Layer ◽  
Moulting Hormone ◽  
The Brain

The ‘moulting hormone’ in Rhodnius is composite. The factor secreted in the dorsum of the brain activates a gland in the thorax which then produces the factor initiating growth and moulting. Implantation of the thoracic gland will induce moulting in the isolated abdomen; implantation of the brain is effective only if the thorax is intact. This system agrees with that described in Lepidoptera and Diptera and is probably widespread in insects. The thoracic gland in Rhodnius consists of a loose network of very large cells, richly supplied with tracheae, spread as a single diffuse layer over the surface of the inner lobes of the thoracic fat-body. These cells go through a cycle of secretory activity which reaches its peak during the critical period. They break down and disappear within 2 days after the insect becomes adult. The adult Rhodnius is caused to moult by implantation of the thoracic gland from a moulting larva; it is not caused to moult by implantation of the brain.

Effect of 20-hydroxyecdysone on neurosecretory cell activity in femaleHyalomma dromedarii synganglion (Acari: Ixodidae)

1988 ◽  
Vol 5 (1-2) ◽  
pp. 101-119 ◽  
Author(s):  
Galila M. Khalil ◽  
Aleya S. Marzouk ◽  
Zakia E. A. Darwish
Keyword(s):  
Neurosecretory Cell ◽  
Cell Activity

Regulatory Influences on Crustacean Neurosecretory Cells

Physiology ◽  
1997 ◽  
Vol 12 (1) ◽  
pp. 16-21
Author(s):  
U Garcia ◽  
H Arechiga
Keyword(s):  
Neurosecretory Cell ◽  
Cell Activity ◽  
Neurosecretory Cells ◽  
Cellular Interactions ◽  
Ionic Mechanisms ◽  
Secretory Neurons ◽  
Endogenous Activity ◽  
New Evidence

During the last decade, new evidence has been produced on the subtle mechanisms by which invertebrate neurosecretory cell activity is regulated. Multiple synaptic and humoral mechanisms regulate the endogenous activity of secretory neurons. Specific cellular interactions and ionic mechanisms have been disclosed, and new insights are now available on the integrative features of invertebrate neurosecretory systems.

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