Effects Of Ecdysone Research Articles

Effects of ecdysone on a Drosophila cell line

When treated by ecdysone, Drosophila cells of the line Kc start aggregating in clumps 24 h later. Different early events occur before this morphological process: DNA synthesis and mitosis stop after 8–10 h; RNA synthesis after a transient stimulation is progressively inhibited.

In vitro activation of neurosecretory brain cells in Mamestra brassicae by β-ecdysone

The effect of ecdysone or of the prothoracic gland on the neurosecretory cells of brains taken from diapausing pupae of the cabbage armyworm, Mamestra brassicae L., was investigated histologically and functionally in vitro. When the diapausing brain was cultured in a medium containing β-ecdysone, the neurosecretory cells of the median group I in the pars intercerebralis increased staining intensity more than those of brains cultured in medium alone. Furthermore, when the prothoracotropic activity of a brain treated with β-ecdysone was compared with that of an untreated brain in vitro, the brain treated with hormone showed higher activity than the untreated one. These results suggest that β-ecdysone acts on the neurosecretory cells of pupal brain in M. brassicae as a positive feedback regulator.

The effect of ecdysone on the fat body cells of the penultimate larvae of Mamestra brassicae.

The capability of beta-ecdysterone to induce autophagocytosis in the fat body cells of penultimate larvae of Mamestra brassicae was investigated both in vivo and in vitro. The hormone proved ineffective when applied for 3 h on the first 3 days of the instar, but it induced the formation of autophagic vacuoles on the 4th day (24 h before ecdysis). This effect became more pronounced when the hormone was administered 10 h before ecdysis. Cells incubated in vitro reacted to ecdysterone more sensitively than cells of similar age treated in vivo. It was concluded that the responsiveness of the fat body cells to ecdysterone as evaluated on the basis of autophagy depends on the age of the larvae. The increased sensitivity of the cells to ecdysterone at the end of the penultimate stage may be related to the decrease of juvenile hormone titre during this period.

Effects of ecdysone and juvenile hormone on epidermal cell development in Hyalophora cecropia

Pupae of Hyalophora cecropia were injected with various doses of β-ecdysone (molting hormone) or juvenile hormone and the epidermal cell ultrastructure was then studied with the electron microscope. The hormonal effects were rapidly manifested and appeared to be cell specific and dose dependent. The initial response to both hormones was an outward blebbing of the apical plasma membrane. Large doses of β-ecdysone elicited both precocious cuticle deposition and premature autophagic vacuole formation. Juvenile hormone prevented the appearance of the autophagic vacuoles which normally preceded cell differentiation into cells capable of adult synthesis. After prolonged exposure to juvenile hormone, there appeared to be an exaggerated separation of the epidermal cells at the basal region suggesting that the juvenile hormone may act at the membrane level.

Effects of ecdysone and juvenile hormone on DNA metabolism of imaginal disks of Drosophila melanogaster

Imaginal disks of Drosophila melanogaster isolated en masse and incubated in Robb's tissue culture medium incorporate 3H-thymidine into nuclear DNA. Both α- and β-ecdysone stimulate the rate of 3H-thymidine incorporation into disk DNA. Concentrations of ecdysone that induce complete evagination of disks in vitro cause the initiation of DNA synthesis in some disk cells. Juvenile hormone has no effect on DNA synthesis in control disks. However, juvenile hormone blocks the ecdysone stimulation of DNA synthesis. It is proposed that juvenile hormone and ecdysone act in a balanced fashion to regulate DNA synthesis in imaginal disks.

In vitro development of insect cells : III. Effects of ecdysone on neonatal larval cells

Both α- and β-ecdysone increased the growth of monocellular spheres in primary cultures of two dipteran species, Aedes taeniorhynchus and Drosophila melanogaster. A limited amount of differentiation was evident in the secretion of one or more membranes, the formation of cellular bridges and the appearance of setae-like structures. A process resembling ecdysis was also observed in one of the D. melanogaster cultures.

Effects of ecdysone on the in vivo growth of wing disks of Calliphora erythrocephala

The normal growth of wing disks is compared with the growth of disks from larvae surgically deprived of ring glands at 5 or 6 days and later unable to form a puparium. During the third instar, the growth of wing disks is constant. It seems to slow down after puparium formation. Twelve days after the ablation of the ring gland, the volume of the wing disks is no different from the volume of the wing disks for 6-day-old larvae. Ecdysone is needed for the growth of imaginal wing disks but the ecdysone peak does not accelerate growth.

Protein synthesis in wing disks of Galleria mellonella: effects of ecdysone and fat body in vitro

The effects of alpha-ecdysone, beta-ecdysone and fat body on protein synthesis in Galleria mellonella wing disks cultured in vitro were investigated. The ecdysones stimulated protein synthesis, but did not maintain it at the higher levels. Fat body enhanced the response of disks to alpha-ecdysone, but this effect was not related to stimulation of morphogenesis by fat body.

Effects of caffeine and aminophylline on adult development of the cecropia silkmoth

Caffeine and aminophylline were potent inhibitors of adult development in the moth, Hyalophora cecropia, when administered prior to initiation of pharate adult development. A dose of 1 mg/g live weight was 100 per cent effective in bringing about this arrest. Cyasterone and α-ecdysone induced development in arrested animals and arrested dauer pupae. Brain transplant and perfusion experments indicated that synthesis or release of brain hormone was disrupted by these drugs. In addition, the effects of ecdysone and perfusion on arrested animals suggested that methylxanthines may also act at other sites in the sequence of events leading to adult development.

Ornithine decarboxylase and polyamines in silkmoth pupal tissues: Effects of ecdysone and injury

1. 1. Ornithine decarboxylase was almost undetectable in fat body and wing tissue from cecropia silkmoth pupae in diapause, but after injection of β-ecdysone, activity rose steeply to a maximum at about 18 h. Injection of water or the inactive analog 22-isoecdysone also induced the enzyme in both tissues, an effect attributable to injury, but in wings β-ecdysone induced a 10-fold greater increase. Cycloheximide blocked induction of the enzyme. 2. 2. Tissues incubated for 12–18 h in culture medium developed a certain level of ornithine decarboxylase. β-Ecdysone in the medium caused definite additional induction, while α-ecdysone had little or no effect. 3. 3. The levels of the polyamines putrescine, spermidine and spermine were determined in a series of tissue samples. Putrescine was relatively concentrated (2–8 mM) in hemolymph, and was elevated 48 h after injection of ecdysone; in fat body, levels were lower and changed less. Spermidine was elevated in fat body and wings 24–36 h after injection of β-ecdysone. Spermine showed no clear pattern of change. 4. 4. Among the consequences of ecdysone action in pupal fat body and wings, induction of ornithine decarboxylase coincides in time with a previously observed peak of RNA synthesis, and maximal spermidine levels appear somewhat later.

Induction of imaginal differentiation by ecdysone in the testes of Ephestia kühniella

The effect of ecdysone on the imaginal differentiation of the testes as indicated by their fusion and torsion was studied. Testes of pharate larvae of the penultimate instar and young pharate pupae (A2) were transplanted into isolated hindparts of 0 to 12 hr old pupae, which served as so-called ‘ in vivo culture chambers’. Ecdysone was given by single or double (24 hr interval) injections of 0·5 μg/animal. Both fusion and torsion could be induced in the transplants. By increasing the hormone dose, the stages of fusion and fusion-torsion were sequentially obtained. The older testes showed a higher responsiveness to a given hormone dose compared with the younger ones. It is presumed that during normogenesis the sequence of differentiation, fusion→torsion, is not induced by an increasing hormone titre and constantly different threshold for these processes, but by a modification of threshold in the course of development.

Spermatogenesis in Cultured Testes of the Cynthia Silkworm: Effects of Ecdysone and of Prothoracic Glands

In vitro spermatogenesis takes place when intact testes are cultured in blood plasma containing ecdysone or certain other steroids possessing ecdysone activity. The ecdysone requirement can be satisfied by culturing the testes in the presence of living, active prothoracic glands. The most likely explanation of these results is that the prothoracic glands constitute the principal source of ecdysone.

Effect of ecdysone and ecdysone analogues on two Balbiani rings of Acricotopus lucidus

The activity of two Balbiani rings (BR-3, BR-4) in the salivary gland of Acricotopus lucidus is controlled by ecdysone. This result agrees with our former conclusion worked out by indirect methods [22]. The injection of ecdysone and ecdysone analogues (ecdysterone, inokosterone) into the last instar larvae led to an inactivation of BR-3 and BR-4 identical to that observed during normal development. The assayed substances were compared in terms of their inactivation ability; they showed activity in the following order: ecdysone > ecdysterone > inokosterone. From a study of the response of BR-3 and BR-4 to different ecdysone concentrations a threshold dose in the range of 10 −12 to 10 −11 μg/mg of larval weight for BR-3 and BR-4 has been obtained.

On the mechanism of hormone action: XIII. Stimulating effects of ecdysone, juvenile hormone and ions on RNA synthesis in fat body cell nuclei from Calliphora erythrocephala isolated by a filtration technique

The effects of ecdysone, juvenile hormone, sodium and potassium ions and some interactions among these factors on RNA polymerase activity were investigated in fat body cell nuclei, isolated from 5–6-day-old larvae by a filtration technique. 1. 1. Sodium ions in a concentration of 50 mM stimulated the RNA synthesis of fat body cell nuclei. This effect could not be observed with potassium ions and was independent of ecdysone. 2. 2. Ecdysone stimulated the RNA synthesis of fat body cell nuclei alone or in the presence of sodium or potassium ions. This effect seemed to be independent of the sodium stimulation. 3. 3. Juvenile hormone was capable of stimulating RNA synthesis of isolated fat body cell nuclei, but this stimulation was dependent on the developmental stage of the animals used. Nuclei isolated from animals with an average weight of 73 mg (5-day-old) responded to juvenile hormone with higher RNA synthesis as the controls, while nuclei of older animals with an average weight of about 98 mg showed no stimulation at all. 4. 4. The effects of ecdysone and juvenile hormone alone on the RNA synthesis could be inhibited by incubating the nuclei with both hormones together.

Effect of ecdysone on protein synthesis in the larval fat body of Calliphora

The effect of ecdysone on protein synthesis in the fat body of isolated abdomens of 6- and 8-day-old larvae of Calliphora erythrocephala has been investigated. A very rapid and significant stimulation of protein synthesis occurred in both the 6- and the 8-day-old larvae. The pattern of 14C-leucine (u.l.) incorporation was rather similar in both age groups. The 6-day-old larvae showed a stimulation of 152 per cent relative to their controls 1 hr after injection of the hormone and reached a maximal stimulation of 172 per cent at 2 hr after hormone administration. The 8-day-old larvae showed a maximal stimulation of 185 per cent relative to their controls within 1 hr after injection of the hormone.

Effects of ecdysone, ecdysterone, and inokosterone on the in vitro initiation of metamorphosis of wing disks of Galleria mellonella

Wing disks of Galleria mellonella initiated metamorphosis when cultured in vitro with ecdysone, ecdysterone, or inokosterone. Even disks from the early part of the final larval stadium were competent to respond to these hormones in vitro. Wing disks synthesized DNA during the first 24 hr of culture, but did not continue to do so unless they were cultured in the presence of ecydsone. Ecdysone-analogues had no effect on DNA synthesis in these experiments. These observations suggest that ecdysone and ecdysterone may have distinct rôles in vivo.

Effects of ecdysone on epidermal cells in which DNA synthesis has been blocked

Polyphemus pupae ready to initiate adult development and ligated abdomens of adult Cecropia and Cynthia moths were injected with an inhibitor of DNA synthesis and with crystalline ecdysone. The results revealed that apolysis—the retraction of the epidermis from the old cuticle—was caused by ecdysone and occurred even when DNA synthesis was blocked and when the rest of the moulting processes failed to occur.

Effect of ecdysone on the puparium formation in irradiated Ephestia kühniella Z.

COMPLETE inhibition of metamorphosis and pupa formation is observed in some insect species when they are irradiated with 20 kr. and more of γ and X-rays1. Puparium formation is delayed in Ephestia kuhniella by doses of 20–30 kr.2–4.

Action of ecdysone on the conversion of 14C-glucose in dauer pupa of the silkworm, Bombyx mori

The effect of ecdysone on the incorporation of 14C-glycose in dauer pupa (brain removed) of Bombyx mori was examined. Incorporation was compared in pupae 18 hr after injection of ecdysone or water. Cumulative recovery of 14CO 2 from 14C-glucose was much the same in the ecdysone-injected pupa as in the control, and in both the recovery of 14CO 2 from 1- 14C-glucose was more than that from 6- 14C-glucose. Labelled glucose was converted to blood trehalose after ecdysone injection but to glycogen in the control. This therefore, suggests the possibility that ecdysone affects the relative activities of enzymes at the branching point of the pathways of trehalose and glycogen syntheses in the fat body, so that the pathway of trehalose synthesis is activated. The blood-sugar content of the 60-day-old dauer pupa with or without the injection of ecdysone was about 1·14 mg/ml, which is much lower than in a normal pupa.

Effect fo ecdysone on incorporation of C-14-leucine into hepatic protein in vitro.

Previous studies(1) indicated that ecdysone, the growth and metamorphosis hormone of insects, may have an effect on mammalian cells also, even though no material yielding a positive bioassay was obtained from human tissues when methods of extraction yielding positive results in insects were used(2). Growth of mammalian cells in tissue culture was inhibited by the hormone(3,4), and a few regressions of sarcoma 180 occurred after injection of ecdysone. In a continuation of these studies, active hormone was added to the fraction of mammalian (murine) liver obtained from centrifugation of homogenates at 14000 × g, and results were compared to samples without the hormone. DL-leucine labeled in position one with C14 was added, and amount of incorporation into protein from zero time for a period of 30 minutes was determined by plating the insoluble material precipitated by trichloracetic acid and counting in the proportional range(5,6,7). (Removal of sources of energy from the system resulted in failure of synth...