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.

Memoirs: The Physiology of Ecdysis in Rhodnius Prolixus (Hemiptera). II. Factors controlling Moulting and ‘Metamorphosis’

1934 ◽  
Vol s2-77 (306) ◽  
pp. 191-222
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
Critical Period ◽  
Secretory Activity ◽  
Rhodnius Prolixus ◽  
Corpus Allatum ◽  
Whole Process ◽  
Definite Interval ◽  
Moulting Hormone ◽  
Moulting Cycle ◽  
The Brain ◽  
Complete Metamorphosis

The five nymphal stages of Rhodnius prolixus are more or less alike. The adult differs markedly from the nymphs. There are thus two phenomena to be considered: simple moulting and moulting coupled with metamorphosis. 1. Causation of Moulting. Moulting occurs at a definite interval after feeding, only one meal being necessary in each stage. There is a ‘critical period’ in the moulting cycle (about 7 days after feeding in the fifth nymph, about 4 days in the earlier nymphs) and removal of the head of the insect before this period prevents moulting. The critical period corresponds with the time when mitotic divisions in the epidermis begin. The blood of insects that have passed the critical period contains a factor or hormone which will induce moulting in insects decapitated soon after feeding. It is suggested that this moulting hormone may be secreted by the corpus allatum, since the cells of this gland show signs of greatest secretory activity during the critical period. Stretching of the abdominal wall provides the stimulus which causes secretion of the moulting hormone. This stimulus is conveyed by nerves to the brain: moulting is prevented by section of the nerve-cord in the prothorax. Section of the nerves between the brain and the corpus allatum appears to prevent moulting; but these experiments were inconclusive. Insects sharing the same blood moult simultaneously. The whole process of growth must therefore be co-ordinated by chemical means; the factors concerned being produced presumably by the growing cells themselves. 2. Causation of Metamorphosis. If fourth or even first nymphs, decapitated soon after feeding, receive the blood from moulting fifth nymphs, they suffer a precocious metamorphosis and develop adult characters. Metamorphosis is therefore brought about by chemical differences in the blood. If fifth nymphs decapitated soon after feeding receive blood from moulting fourth nymphs, they also moult; showing that the moulting factor is the same at all stages. The absence of metamorphosis in normal nymphs before the fifth stage must therefore be due to an inhibitory factor or hormone in the blood. This is proved by the fact that if a fifth nymph decapitated soon after feeding receives the blood from a moulting fourth nymph (not deprived of its head) it develops characters much more like those of a nymph than an adult. The inhibitory hormone is normally produced in such small quantities that simple dilution of the blood of a moulting fourth nymph with that of another fourth nymph (decapitated soon after feeding) causes them both to suffer metamorphosis. The head is necessary for the secretion of the inhibitory hormone. This hormone seems to be secreted after the moulting hormone. Thus if series of fourth, third, second, or first nymphs are decapitated around the critical period, some of them show more or less complete metamorphosis. Others show characters intermediate between those of nymphs and adults. The bearing of these results on the phenomena of diapause and prothetely is discussed.

Effects of Sub-Lethal High Temperature on An Insect, Rhodnius Prolixus (Stål.)

1968 ◽  
Vol 48 (3) ◽  
pp. 465-473
Author(s):  
A. Y. K. OKASHA
Keyword(s):  
Cell Division ◽  
High Temperature ◽  
Mitotic Activity ◽  
High Temperatures ◽  
Critical Period ◽  
Rhodnius Prolixus ◽  
Epidermal Cells ◽  
Complete Development ◽  
Moulting Hormone ◽  
The Brain

1. In Rhodnius larvae, when moulting is delayed under normal temperature conditions by exposure to high temperature directly after feeding, the brain is needed for a period longer than normal to complete development, i.e. the critical period is postponed. 2. This is associated with a delay in the activation of the thoracic glands and in the mitotic activity in the epidermis. 3. It is suggested that high temperature may act directly on the brain thus inhibiting the secretion of its hormone, although other possibilities are also discussed. 4. The process of wound heating at normal and high temperatures is compared. Injury of the integument results in the ‘activation’ of the epidermal cells and their migration towards the wound. Consequently, a zone of sparse cells is formed which persists at high temperature, since cell division in the epidermis is inhibited. 5. The bearing of the inhibition of cell division on the cessation of moulting at high temperature, even in the presence of the moulting hormone, is discussed.

scholarly journals The Determination of Characters at Metamorphosis in Rhodnius Prolixus (Hemiptera)

1940 ◽  
Vol 17 (2) ◽  
pp. 201-223 ◽  
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
Critical Period ◽  
Fat Body ◽  
Corpus Allatum ◽  
Adult Type ◽  
Histological Changes ◽  
Short Time ◽  
The Brain ◽  
New Hypothesis ◽  
Partial Reversion

Nymphs of Rhodnius decapitated 24 hr. after feeding can be induced to moult by implanting into the abdomen the dorsal region of the protocerebrum removed from other nymphs during the critical period. Implantation of other parts of the brain, of the corpus allatum, and of fat body from the same insects did not cause moulting. The presence of large nerve cells with fuchsinophil inclusions discovered by Hanström in this region of the brain has been confirmed. The histological changes in the epidermis of the abdomen and the distribution of mitoses at an imaginal moult and at a nymphal moult have been compared. During a nymphal moult mitoses occur all over the tergites; during an imaginal moult they are largely confined to the intersegmental membranes and the periphery of the abdomen, and there is a more extensive breakdown of existing cells. If 5th stage nymphs in the course of moulting to become adults receive "inhibitory hormone" from young nymphs, they may be caused to "switch over" to nymphal development. Such a "switch over" soon becomes impossible for the most specialized structures of the adult; other structures follow in turn; but the general cuticle of the tergites may still be influenced up to a short time before it is due to be laid down. The various faculties of a given cell can become determined to some extent independently of one another. Isolated fragments of cuticle and epidermis from Rhodnius adults may be induced to moult, more than once, by transplantation to young moulting nymphs. Decapitated Cimex adults may be caused to moult again if they receive blood from moulting Rhodnius nymphs; but they lay down a normal cuticle with bristles only if they have become adult very recently. Decapitated Rhodnius adults may be caused to moult again if they receive blood from two moulting 5th stage nymphs. They lay down a cuticle of normal adult type even when they have been adults for several months. The old skin is digested up to the level of the exocuticle. If such moulting adults are provided with inhibitory hormone from the corpus allatum of young nymphs, they show a partial reversion to nymphal characters when they moult. This change probably does not extend to the most specialized imaginal structures; but the pigmentation and the structure of the general cuticle, and of the bristles it carries, may become partially nymphal again. The "determination" of imaginal or nymphal characters thus takes place at different times in different organs. And for some characters, at least, such determination is not irrevocable. In the light of these results a new hypothesis is put forward to explain the action of the inhibitory hormone in controlling metamorphosis. This work was begun during a stay of three months in Berlin-Dahlem as the guest of the Kaiser-Wilhelm Gesellschaft, to whom my thanks are due. Throughout this stay I was indebted to Prof. A. Kühn and his colleagues at the Kaiser-Wilhelm Institut für Biologie for every assistance and for much stimulating discussion.

The Dermal Glands of Rhodnius Prolixus

1969 ◽  
Vol 27 ◽  
pp. 258-259
Author(s):  
J. E. Lai-Fook
Keyword(s):  
Fine Structure ◽  
Secretory Activity ◽  
Rhodnius Prolixus ◽  
Outermost Layer ◽  
Cement Layer ◽  
Dermal Glands

Dermal glands are epidermal derivatives which are reported to secrete either the cement layer, which is the outermost layer of the epicuticle or some component of the moulting fluid which digests the endocuticle. The secretions do not show well-defined staining reactions and therefore they have not been positively identified. This has contributed to another difficulty, namely, that of determining the time of secretory activity. This description of the fine structure of the developing glands in Rhodnius was undertaken to determine the time of activity, with a view to investigating their function.

Central and Peripheral Clock Control of Circadian Feeding Rhythms

2021 ◽  
pp. 074873042110458
Author(s):  
Carson V. Fulgham ◽  
Austin P. Dreyer ◽  
Anita Nasseri ◽  
Asia N. Miller ◽  
Jacob Love ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Circadian Clock ◽  
Feeding Behavior ◽  
Molecular Clock ◽  
Fat Body ◽  
Molecular Clocks ◽  
Central Brain ◽  
Feeding Rhythms ◽  
Free Running ◽  
The Brain

Many behaviors exhibit ~24-h oscillations under control of an endogenous circadian timing system that tracks time of day via a molecular circadian clock. In the fruit fly, Drosophila melanogaster, most circadian research has focused on the generation of locomotor activity rhythms, but a fundamental question is how the circadian clock orchestrates multiple distinct behavioral outputs. Here, we have investigated the cells and circuits mediating circadian control of feeding behavior. Using an array of genetic tools, we show that, as is the case for locomotor activity rhythms, the presence of feeding rhythms requires molecular clock function in the ventrolateral clock neurons of the central brain. We further demonstrate that the speed of molecular clock oscillations in these neurons dictates the free-running period length of feeding rhythms. In contrast to the effects observed with central clock cell manipulations, we show that genetic abrogation of the molecular clock in the fat body, a peripheral metabolic tissue, is without effect on feeding behavior. Interestingly, we find that molecular clocks in the brain and fat body of control flies gradually grow out of phase with one another under free-running conditions, likely due to a long endogenous period of the fat body clock. Under these conditions, the period of feeding rhythms tracks with molecular oscillations in central brain clock cells, consistent with a primary role of the brain clock in dictating the timing of feeding behavior. Finally, despite a lack of effect of fat body selective manipulations, we find that flies with simultaneous disruption of molecular clocks in multiple peripheral tissues (but with intact central clocks) exhibit decreased feeding rhythm strength and reduced overall food intake. We conclude that both central and peripheral clocks contribute to the regulation of feeding rhythms, with a particularly dominant, pacemaker role for specific populations of central brain clock cells.

scholarly journals The ex-illiterate brain: The critical period, cognitive reserve and HAROLD model

2009 ◽  
Vol 3 (3) ◽  
pp. 222-227 ◽  
Author(s):  
Maria Vania Silva Nunes ◽  
Alexandre Castro-Caldas ◽  
Dolores Del Rio ◽  
Fernado Maestú ◽  
Tomás Ortiz
Keyword(s):  
Recognition Test ◽  
Cognitive Skills ◽  
Critical Period ◽  
Cognitive Reserve ◽  
Brain Activity ◽  
High Educational Level ◽  
Critical Periods ◽  
Language Recognition ◽  
Regular Time ◽  
The Brain

Abstract The lifelong acquisition of cognitive skills shapes the biology of the brain. However, there are critical periods for the best use of the brain to process the acquired information. Objectives: To discuss the critical period of cognitive acquisition, the concept of cognitive reserve and the HAROLD (Hemispheric Asymmetry Reduction in Older adults) model. Methods: Seven women who learned how to read and to write after the age of 50 (ex-illiterates) and five women with 10 years of regular schooling (controls) were submitted to a language recognition test while brain activity was being recorded using magnetoencephalography. Spoken words were delivered binaurally via two plastic tubs terminating in ear inserts, and recordings were made with a whole head magnetometer consisting of 148 magnetometer coils. Results: Both groups performed similarly on the task of identifying target words. Analysis of the number of sources of activity in the left and right hemispheres revealed significant differences between the two groups, showing that ex-illiterate subjects exhibited less brain functional asymmetry during the language task. Conclusions: These results should be interpreted with caution because the groups were small. However, these findings reinforce the concept that poorly educated subjects tend to use the brain for information processing in a different way to subjects with a high educational level or who were schooled at the regular time. Finally, the recruiting of both hemispheres to tackle the language recognition test occurred to a greater degree in the ex-illiterate group where this can be interpreted as a sign of difficulty performing the task.

scholarly journals Downregulation of a satiety signal from peripheral fat bodies improves visual attention while reducing sleep need in Drosophila

2019 ◽  
Author(s):  
Deniz Ertekin ◽  
Leonie Kirszenblat ◽  
Richard Faville ◽  
Bruno van Swinderen
Keyword(s):  
Visual Attention ◽  
Cognitive Processes ◽  
Fat Body ◽  
Sleep Loss ◽  
Genetically Engineered ◽  
Night Time ◽  
Selective Visual Attention ◽  
Negative Side Effects ◽  
Fat Bodies ◽  
The Brain

AbstractSleep is vital for survival. Yet, under environmentally challenging conditions such as starvation, animals suppress their need for sleep. Interestingly, starvation-induced sleep loss does not evoke a subsequent sleep rebound. Little is known about how starvation-induced sleep deprivation differs from other types of sleep loss, or why some sleep functions become dispensable during starvation. Here we demonstrate that downregulation of unpaired-2 (upd2, the Drosophila ortholog of leptin), is sufficient to mimic a starved-like state in flies. We use this ‘genetically starved’ state to investigate the consequences of a starvation signal on visual attention and sleep in otherwise well-fed flies, thereby sidestepping the negative side-effects of undernourishment. We find that knockdown of upd2 in the fat body is sufficient to suppress sleep while also increasing selective visual attention and promoting night-time feeding. Further, we show that this peripheral signal is integrated in the fly brain via insulin-expressing cells. Together, these findings identify a role for peripheral tissue-to-brain interactions in the simultaneous regulation of sleep and attention, to potentially promote adaptive behaviors necessary for survival in hungry animals.Author SummarySleep is important for maintaining both physiological (e.g., metabolic, immunological, and developmental) and cognitive processes, such as selective attention. Under nutritionally impoverished conditions, animals suppress sleep and increase foraging to locate food. Yet it is currently unknown how an animal is able to maintain well-tuned cognitive processes, despite being sleep deprived. Here we investigate this question by studying flies that have been genetically engineered to lack a satiety signal, and find that signaling from fat bodies in the periphery to insulin-expressing cells in the brain simultaneously regulates sleep need and attention-like processes.

scholarly journals The transcriptomic signature of low aggression honey bees resembles a response to infection

2020 ◽  
Author(s):  
Clare C Rittschof ◽  
Benjamin E.R. Rubin ◽  
Joseph H. Palmer
Keyword(s):  
Health Outcomes ◽  
Honey Bee ◽  
Fat Body ◽  
Physiological State ◽  
Acute Infection ◽  
Differentially Expressed ◽  
Molecular Response ◽  
Transcriptomic Signature ◽  
Behavioral Maturation ◽  
The Brain

Abstract Background: Behavior reflects an organism's health status. Many organisms display a generalized suite of behaviors that indicate infection or predict infection susceptibility. We apply this concept to honey bee aggression, a behavior that has been associated with positive health outcomes in previous studies. We sequenced the transcriptomes of the brain, fat body, and midgut of adult sibling worker bees who developed as pre-adults in relatively high versus low aggression colonies. Previous studies showed that this pre-adult experience impacts both aggressive behavior and resilience to pesticides. We performed enrichment analyses on differentially expressed genes to determine whether variation in aggression resembles the molecular response to infection. We further assessed whether the transcriptomic signature of aggression in the brain is similar to the neuromolecular response to acute predator threat, exposure to a high-aggression environment as an adult, or adult behavioral maturation. Results: Across all three tissues assessed, genes that are differentially expressed as a function of aggression significantly overlap with genes whose expression is modulated by a variety of pathogens and parasitic feeding. In the fat body, and to some degree the midgut, our data specifically support the hypothesis that low aggression resembles a diseased or parasitized state. However, we find little evidence of active infection in individuals from the low aggression group. We also find little evidence that the brain molecular signature of aggression is enriched for genes modulated by social cues that induce aggression in adults. However, we do find evidence that genes associated with adult behavioral maturation are enriched in our brain samples. Conclusions: Results support the hypothesis that low aggression resembles a molecular state of infection. This pattern is most robust in the peripheral fat body, an immune responsive tissue in the honey bee. We find no evidence of acute infection in bees from the low aggression group, suggesting the physiological state characterizing low aggression may instead predispose bees to negative health outcomes when they are exposed to additional stressors. The similarity of molecular signatures associated with the seemingly disparate traits of aggression and disease suggests that these characteristics may, in fact, be intimately tied.

Synthesis of a haemolymph hexamerin by the fat body and testis of Rhodnius prolixus

1994 ◽  
Vol 24 (1) ◽  
pp. 59-67 ◽  
Author(s):  
F.S. Faria ◽  
E.S. Garcia ◽  
S. Goldenberg
Keyword(s):  
Fat Body ◽  
Rhodnius Prolixus

Haemolymph Proteins and Yolk Formation in Rhodnius Prolixus Stål

1965 ◽  
Vol 43 (3) ◽  
pp. 425-431
Author(s):  
G. C. COLES
Keyword(s):  
Cellulose Acetate ◽  
Total Protein ◽  
Egg Production ◽  
Fat Body ◽  
Rhodnius Prolixus ◽  
Hormonal Control ◽  
Protein Fractions ◽  
Yolk Formation ◽  
Specific Proteins

1. There are two adult-specific proteins in the haemolymph of Rhodnius. They appear to be formed in the fat body. 2. The two proteins are absorbed by the oocytes and form the bulk of the soluble egg proteins. 3. The changes in the concentration of total protein in the haemolymph and of four protein fractions, as separated on cellulose acetate, do not reflect egg production. This may be a consequence of the hormonal control of reproduction.

Sign in / Sign up

Export Citation Format

Share Document