Memoirs: The function of the Corpus Allatum in the Growth and Reproduction of Rhodnius Prolixus (Hemiptera)

1936 ◽  
Vol s2-79 (313) ◽  
pp. 91-121
Author(s):  
V. B. Wigglesworth
Keyword(s):  
Adult Female ◽  
Normal Activity ◽  
Inhibitory Effect ◽  
Corpus Allatum ◽  
The Body ◽  
Egg Development ◽  
Accessory Glands ◽  
Degree Of Differentiation ◽  
Moulting Hormone ◽  
Transplantation Experiments

The Corpus Allatum and Moulting in Bhodnius. 1. The stretching of the cuticle which initiates moulting is necessary only as a stimulus for the secretion of the moulting hormone. The hormone so produced will induce moulting in unfed nymphs. 2. The simultaneous moulting of joined insects is dependent on the continuity of the epidermis established between them. But moulting can be induced by the medium of the blood without contact between the tissues. 3. The moulting hormone from Rhodnius will induce moulting in bugs of the allied genus Triatoma and in the bed-bug, Cimex. The epidermis of these joined insects grows together during the process. 4. Some rather indirect experimental evidence that the corpus allatum secretes the moulting hormone is given. 5. The corpus allatum secretes the ‘inhibitory hormone’ which prevents metamorphosis in the earlier nymphal stages. Fifth-stage nymphs with the corpus allatum of 3rd- or 4th-stage nymphs implanted in them give rise to ‘6th-stage’ nymphs. These ‘6th-stage’ nymphs may give rise to ‘7th-stage’ nymphs when they moult again. In some transplantation experiments the characters all over the body may be intermediate between nymph and adult; or nymphal characters may only be developed near the implant. 6. The inhibitory effect is non-specific as between Rhodnius, Triatoma, and Cimex. 7. The corpus allatum also determines the characters of each nymphal instar by limiting the degree of differentiation towards the adult form which occurs during the moult. 8. In the phenomenon of ‘inhibition of metamorphosis’ there seem to be two elements: (i) deposition of the new cuticle follows rapidly upon the initiation of growth and hence differentiation of the adult characters is arrested; (ii) so long as differentiation is arrested in this way the cells are capable of renewed growth and will respond again to the ‘moulting hormone’. 9. Whether the ‘moulting hormone’ is chemically distinct from the ‘inhibitory hormone’ is not proved. The Corpus Allatum and Reproduction in Rhodnius. 1. In the adult female the corpus allatum is necessary for the production of ripe eggs. The secretion from the corpus allatum of Triatoma females will cause egg development in Rhodnius. 2. In the absence of this secretion the oocytes continue to grow so long as they are connected to the nurse cells. They die and are absorbed when their nutrition is taken over by the follicular cells. 3. The moulting hormone of the nymphal stages will not cause egg development in the adult female; nor will the egg-forming hormone induce moulting. 4. The corpus allatum in the adult male is necessary for the normal activity of the accessory glands. Its secretion will induce egg development in the adult female; and the secretion from the female will activate the accessory glands of the male.

The Functions of the Corpus Allatum in Rhodnius Prolixus (Hemiptera)

1948 ◽  
Vol 25 (1) ◽  
pp. 1-15
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Juvenile Hormone ◽  
Adult Female ◽  
Corpus Allatum ◽  
Relative Importance ◽  
Egg Development ◽  
Mature Adult ◽  
Two Factors ◽  
The Central Nervous System

Two factors are involved in the control of metamorphosis in Rhodnius: (a) The corpus allatum of the 5th-stage nymph no longer secretes the juvenile hormone (inhibitory hormone). The latent imaginal characters can thus be realized. (b) The corpus allatum in the 5th-stage nymph, particularly in the later stages of moulting, actively favours the production of imaginal characters. The evidence suggests that this activity (b) consists, not in the secretion of a metamorphosis promoting hormone favouring adult differentiation in the tissues directly, but in the elimination of the small quantities of juvenile hormone persisting in the blood and tissues. If we suppose that these two factors differ in relative importance in different insects we may perhaps have the basis for a theory of metamorphosis applicable to all groups of insects. The corpus allatum of the mature adult Rhodnius again begins to secrete the juvenile hormone; and the juvenile hormone of the 4th-stage nymph will induce egg development in the adult female. It is probable that the yolk-forming hormone and the juvenile hormone are identical. The sequence in the secretory activities of the corpus allatum, and so the number of instars, is controlled by some other centre, perhaps in the central nervous system.

Inhibition of Yeast Growth by Tryptamine and Recovery with Tryptophan

2020 ◽  
Vol 16 (1) ◽  
pp. 48-52 ◽  
Author(s):  
Chandrika Kadkol ◽  
Ian Macreadie
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Competitive Inhibition ◽  
Yeast Species ◽  
Inhibitory Effect ◽  
The Body ◽  
Inhibitory Effects ◽  
Trna Synthetases ◽  
Fermentative Growth ◽  
Biogenic Monoamine

Background: Tryptamine, a biogenic monoamine that is present in trace levels in the mammalian central nervous system, has probable roles as a neurotransmitter and/or a neuromodulator and may be associated with various neuropsychiatric disorders. One of the ways tryptamine may affect the body is by the competitive inhibition of the attachment of tryptophan to tryptophanyl tRNA synthetases. Methods: This study has explored the effects of tryptamine on growth of six yeast species (Saccharomyces cerevisiae, Candida glabrata, C. krusei, C. dubliniensis, C. tropicalis and C. lusitaniae) in media with glucose or ethanol as the carbon source, as well as recovery of growth inhibition by the addition of tryptophan. Results: Tryptamine was found to have an inhibitory effect on respiratory growth of all yeast species when grown with ethanol as the carbon source. Tryptamine also inhibited fermentative growth of Saccharomyces cerevisiae, C. krusei and C. tropicalis with glucose as the carbon source. In most cases the inhibitory effects were reduced by added tryptophan. Conclusion: The results obtained in this study are consistent with tryptamine competing with tryptophan to bind mitochondrial and cytoplasmic tryptophanyl tRNA synthetases in yeast: effects on mitochondrial and cytoplasmic protein synthesis can be studied as a function of growth with glucose or ethanol as a carbon source. Of the yeast species tested, there is variation in the sensitivity to tryptamine and the rescue by tryptophan. The current study suggests appropriate yeast strains and approaches for further studies.

Sophistication of Body Concept in Process-Reactive Schizophrenia

1971 ◽  
Vol 32 (2) ◽  
pp. 567-570
Author(s):  
Robert Cancro
Keyword(s):  
Significant Relationship ◽  
Rating Scale ◽  
The Body ◽  
Psychological Differentiation ◽  
Drug Ingestion ◽  
Underlying Basis ◽  
Body Concept ◽  
Degree Of Differentiation ◽  
The Relationship

The underlying basis for the process-reactive classification is unclear, although some authors offer differences in psychological differentiation as an explanation. This study examined the relationship between the degree of differentiation of the body concept and the process-reactive continuum, which was measured by the Prognostic Rating Scale and the subsequent total number of nights of hospitalization over a 3-yr. period for 51 Ss. There was no significant relationship—linear or curvilinear—between these variables in this sample of acute schizophrenics in whom drug ingestion, chronicity, and length of current hospitalization were controlled.

scholarly journals Molecular mechanisms of control of differentiation of regulatory t-lymphocytes by exogenous melatonin

2019 ◽  
Vol 484 (2) ◽  
pp. 224-227
Author(s):  
N. S. Glebezdina ◽  
A. A. Olina ◽  
I. V. Nekrasova ◽  
E. M. Kuklina
Keyword(s):  
T Cells ◽  
Molecular Mechanisms ◽  
Inhibitory Effect ◽  
The Body ◽  
Membrane Receptors ◽  
Cell Subpopulation ◽  
Exogenous Melatonin ◽  
Regulatory T Lymphocytes ◽  
Treg Differentiation

We investigated the role of epiphyseal hormone melatonin in the differentiation of naive CD4+T cells into regulatory T cells (Treg). The hormone at physiological and pharmacological concentrations inhibited Treg differentiation, decreasing both the proportion of CD4+FOXP3+ cells in the culture and the level of TGF‑β, the key cytokine for this T cell subpopulation. The inhibitory effect of exogenous melatonin was due to its interaction with the membrane receptors MT1 and MT2. At the same time, the signals realized through RORa — the nuclear receptor for melatonin — stimulated Treg formation; however, they were considerably weaker than the signals from the membrane receptors and were overlapped by the latter. Since the Treg subpopulation plays an important role in physiological and pathological processes in the body, the revealed effects of melatonin should be taken into account in its therapeutic use.

The Physiology of Contractile Vacuoles

1960 ◽  
Vol 37 (1) ◽  
pp. 73-82
Author(s):  
J. A. KITCHING ◽  
J. E. PADFIELD ◽  
M. H. ROGERS
Keyword(s):  
Body Surface ◽  
Normal Activity ◽  
The Body ◽  
Contractile Vacuole ◽  
Diffusion Constants ◽  
Contractile Vacuoles

1. The suctorian Discophrya collini (Root) has been subjected to D2O-H2O mixtures containing up to 99.7% D2O. 2. In 25% D2O or over there is a rapid but temporary shrinkage of the body. This shrinkage is difficult to estimate owing to the wrinkling of the body surface, but amounts to at least 10% in the undiluted (99.7%)D2O. 3. During the period of temporary shrinkage the contractile vacuole ceases activity. Normal activity is resumed when the normal volume is regained. In concentrations of D2O too low to cause shrinkage there is a temporary fall in the rate of vacuolar output. 4. Return to H2O leads to a brief but often very considerable rise in vacuolar output. 5. It is concluded that D2O penetrates less rapidly than H2O. A difference of at least 10% in the diffusion constants in the membrane would be required to explain our results. We cannot exclude this as unreasonable from our data, although an explanation based on differences in the equilibrium properties of D2O and H2O might also be invoked.

Mesencephalic hemisection in the primate

1965 ◽  
Vol 209 (2) ◽  
pp. 312-318
Author(s):  
Fred A. Mettler
Keyword(s):  
Chronic Condition ◽  
Red Nucleus ◽  
Inhibitory Effect ◽  
Passive Movement ◽  
The Body ◽  
Inhibitory Influence ◽  
Present Communication ◽  
Different Types ◽  
Rostral Part

Relatively little information is available about the subacute and chronic condition of hemidecerebrate monkeys. The present communication deals, not with ablations of one-half of the supratentorial neuraxis, but with the effects of four different types of mesencephalic hemisections—cuts above and below the tectum, and cuts passing through the rostral and caudal parts of the magnocellular part of the red nucleus. None of these hemisections produced extensor rigidity on either side of the body. Rigidity, in the sense of resistance to passive movement, was only encountered as a flexor phenomenon. This appeared contralaterally when a high mesencephalic hemisection passed through the rostral part of the red nucleus. Examination of the evidence seems to suggest that in order for such a phenomenon to appear a subthalamically crossing tegmental mechanism needs to be severed in addition to the projection fibers in the pes pedunculi (which ultimately cross in the medulla). The tegmental crossing mechanism seems to exert a flexor inhibitory effect, in contrast to the extensor inhibitory influence which originates in the cortex.

Effect of Stationary Objects on Illusory Forward Self-Motion Induced by a Looming Display

Perception ◽  
1988 ◽  
Vol 17 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Masao Ohmi ◽  
Ian P Howard
Keyword(s):  
Inhibitory Effect ◽  
The Body ◽  
Body Motion ◽  
Depth Cues ◽  
Circular Vection ◽  
Stationary Objects ◽  
Self Motion ◽  
Stationary Background

It has previously been shown that when a moving and a stationary display are superimposed, illusory self-rotation (circular vection) is induced only when the moving display appears as the background. Three experiments are reported on the extent to which illusory forward self-motion (forward vection) induced by a looming display is inhibited by a superimposed stationary display as a function of the size and location of the stationary display and of the depth between the stationary and looming displays. Results showed that forward vection was controlled by the display that was perceived as the background, and background stationary displays suppressed forward vection by about the same amount whatever their size and eccentricity. Also, the perception of foreground — background properties of competing displays determined which controlled forward vection, and this control was not tied to specific depth cues. The inhibitory effect of a stationary background on forward vection was, however, weaker than that found with circular vection. This difference makes sense because, for forward body motion, the image of a distant scene is virtually stationary whereas, when the body rotates, it is not.

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