Corpora Cardiaca-corpora Allata Complex Research Articles

Mating-Induced Differential Peptidomics of Neuropeptides and Protein Hormones in Agrotis ipsilon Moths.

In many insects, mating induces drastic changes in male and female responses to sex pheromones or host-plant odors. In the male moth Agrotis ipsilon, mating induces a transient inhibition of behavioral and neuronal responses to the female sex pheromone. As neuropeptides and peptide hormones regulate most behavioral processes, we hypothesize that they could be involved in this mating-dependent olfactory plasticity. Here we used next-generation RNA sequencing and a combination of liquid chromatography, matrix assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, and direct tissue profiling to analyze the transcriptome and peptidome of different brain compartments in virgin and mated males and females of A. ipsilon. We identified 37 transcripts encoding putative neuropeptide precursors and 54 putative bioactive neuropeptides from 23 neuropeptide precursors (70 sequences in total, 25 neuropeptide precursors) in different areas of the central nervous system including the antennal lobes, the gnathal ganglion, and the corpora cardiaca-corpora allata complex. Comparisons between virgin and mated males and females revealed tissue-specific differences in peptide composition between sexes and according to physiological state. Mated males showed postmating differences in neuropeptide occurrence, which could participate in the mating-induced olfactory plasticity.

Biological activity and identification of neuropeptides in the neurosecretory complexes of the cabbage pest insect,Mamestra brassicae(Noctuidae; Lepidoptera)

The need for more environmentally sound strategies of plant protection has become a driving force in physiological entomology to combat insect pests more efficiently. Since neuropeptides regulate key biological processes, these "special agents" or their synthetic analogues, mimetics, agonists or antagonists may be useful tools. We examined brain-suboesophageal ganglia and corpora cardiaca-corpora allata complexes of the cabbage moth, Mamestra brassicae, in order to obtain clues about possible peptide candidates which may be appropriate for the biological control of this pest. With the aid of bioassays, reversed phase high performance liquid chromatography, and mass spectrometry, five neuropeptides were unequivocally identified and the presence of a further three were inferred solely by comparing mass spectra with known peptides. Only one neuropeptide with adipokinetic capability was identified in M. brassicae. Data from the established homologous bioassay indicated that the cabbage moths rely on a lipid-based metabolism which is aided by an adipokinetic hormone (viz. Manse-AKH) that had previously been isolated in many different lepidopterans. Other groups of neuropeptides identified in this study are: FLRFamides, corazonin, allatostatin and pheromonotropic peptide.

Allatotropic and nervous control of corpora allata in the adult male loreyi leafworm, Mythimna loreyi (Lepidoptera: Noctuidae)

SummaryAllatotropic activity is found in methanolic extracts of the brain–suboesophageal ganglion (SOG)–corpora cardiaca (CC) complex from virgin males of Mythimna loreyi Duponchel (Lepidoptera, Noctuidae). Corpora allata (CA) from 6‐day‐old virgin males exhibit low rates of release of Juvenile Hormone (JH) acid (JHA) in vitro. Release of JHA can be activated by the addition of an extract of brain–SOG–CC complex in a dose‐dependent manner, and this allatotropic activation can be sustained consistently in the continuous presence of such extracts. Based on its trypsin sensitivity and heat stability, the allatotropic factor is most likely a peptide. The allatotropic activity is dependent on the concentration of calcium ions in the medium, with the highest activation achieved beyond 2 m m. The results of nerve transection experiments suggest that both nervi corporis allati I (NCA I) and NCA II are involved in mediating the allatotropic control of CA in vitro. Isolated CA alone show significantly higher rates of release of JHA than the intact brain–SOG–CC–CA complex during the first 3 h of incubation, but the release of JHA reaches almost the same range in both groups by the end of the fourth hour of incubation.

Role of Brain, Ventral Nerve Cord, and Corpora Cardiaca-Corpora Allata Complex in the Reproductive Behavior of Female Tobacco Budworm (Lepidoptera: Noctuidae)

Various surgical treatments were used to determine the role of the brain, ventral nerve cord (VNC), and corpora cardiaca- corpora allata complex in the reproductive behavior of Heliothis virescens (F.). VNC-transected females mated successfully and exhibited increased egg production after mating, suggesting that an intact VNC is not required for calling, sex pheromone emission, mating, or mating-induced oogenesis. The patterns of increase in egg production in decapitated, virgin females and mated, decapitated females were similar. Allatectomized females called less overall than did the others, but all females called and were able to mate with males. The allatectomized, virgin females produced <20 eggs in total, whereas allatectomized females mated to normal males produced 90 eggs. Mated females decapitated immediately after uncoupling produced nearly 3 times as many eggs as decapitated, virgin females. Females decapitated at 6 h after uncoupling showed a further significant stimulation in egg maturation. These findings suggest that the male transfers some factor that, by itself, stimulates oogenesis.

Peptidergic Control of the Corpus Cardiacum-Corpora Allata Complex of Locusts

The brain-corpora cardiaca-corpora allata complex of insects is the physiological equivalent of the brain-hypophysis axis of vertebrates. In locusts there is only one corpus cardiacum as a result of fusion, while most other insect species have a pair of such glands. Like the pituitary of vertebrates, the corpus cardiacum consists of a glandular lobe and a neurohemal lobe. The glandular lobe synthesizes and releases adipokinetic hormones. In the neurohemal part many peptide hormones, which are produced in neurosecretory cells in the brain, are released into the hemolymph. The corpora allata, which have no counterpart in vertebrates, synthesize and release juvenile hormones. The control of the locust corpus cardiacum-corpora allata complex appears to be very complex. Numerous brain factors have been reported to have an effect on biosynthesis and release of juvenile hormone or adipokinetic hormone. Many neuropeptides are present in nerves projecting from the brain into the corpora cardiaca-corpora allata complex, the most important ones being neuroparsins, ovary maturating parsin, insulin-related peptide, diuretic peptide, tachykinins, FLRFamides, FXPRLamides, accessory gland myotropin I, crustacean cardioactive peptide, and schistostatins. In this paper, the cellular distribution, posttranslational processing, peptide-receptor interaction, and inactivation of these peptides are reviewed. In addition, the signal transduction pathways in the release of adipokinetic hormone and juvenile hormone from, respectively, the corpora cardiaca and corpora allata are discussed.

Neuroendocrine control of diapause hormone secretion in the silkworm, Bombyx mori

To clarify the control mechanism of diapause hormone (DH) secretion in the silkworm Bombyx mori a series of anatomical and pharmacological experiments were carried out. The arrangement of `diapause' and `non-diapause' eggs in the ovarioles of the moths was determined by the coloration method to estimate the accumulation of 3-hydroxykynurenine in the eggs. The females destined to lay non-diapause eggs (non-diapause producers) had diapause eggs in their ovaries if their subesophageal ganglions (Sg) had been surgically removed at 2 days after larval–pupal ecdysis or later. In contrast when the surgical extirpation extended to the brain and the corpora cardiaca (CC)–corpora allata (CA) complex in addition to the Sg, the non-diapause producers had no diapause eggs. When the Sg was removed from the females destined to lay diapause eggs (diapause-producers), diapause eggs appeared in response to the treatment at 2 days after larval–pupal ecdysis, but the appearance of diapause eggs was delayed by 2 days when the brain–CC–CA complex was included among the organs removed. These observations suggested that DH is produced in Sg and transferred to the CC–CA complex, and that the secretion of DH from the complex is suppressed in non-diapause producers. The pattern of diapause and non-diapause eggs induced by the transection of the subesophageal connective in diapause and non-diapause producers suggested a regenerative and secretory capacity of the neurosecretory cells after the operation. The appearance of diapause eggs in non-diapause producers with transected protocerebrum of the brain confirmed that there was an inhibitory center in the protocerebrum. Changes in parts of the ovarioles containing diapause and non-diapause eggs with time of injection of γ-aminobutyric acid (GABA) and picrotoxin suggested that a GABAergic inhibitory mechanism in DH secretion may be active in non-diapause producers but inactive in diapause producers throughout the pupal stage.

Localization of the Pupal Melanization Reducing Factor of Inachis io (L.) and Comparison with Melanization and Reddish Coloration Hormone

In Inachis io, a pupal melanization reducing factor (PMRF) which controls morphological color adaptation is located in the brain, suboesophageal ganglion, thoracic ganglia, and all abdominal ganglia. Higher PMRF amounts were extracted from abdominal ganglia than from the anterior ganglia. No PMRF activity could be found in the Corpora cardiaca-Corpora allata complex, in segmentally branching nerves of abdominal ganglia and their connectives. Extracts from brain-thoracic ganglia and abdominal ganglia complex of I. io contained also a factor with melanization and reddish coloration hormone (MRCH) activity in Pseudaletia separata and with pheromone biosynthesis activating neuropeptide (PBAN) activity in Bom-byx mori. However, injection of synthetic Pseudaletia pheromonotropin (Pss-PT) (= Pss-MRCH) into prepupae of I. io did not yield a melanization reducing effect. Therefore, PMRF and the PBAN/MRCH related neuropeptides seem to be different molecules. The PBAN-like factor from I. io is possibly related to the myotropins and pyrokinins of insects

Responsiveness of the adult cricket (Gryllus bimaculatus and Acheta domesticus) retrocerebral complex to allatostatin-1 from a cockroach, Diploptera punctata.

Brain-retrocerebral complexes of female crickets, Gryllus bimaculatus and Acheta domesticus, treated with antibody to allatostatin-1 from a cockroach, Diploptera punctata, show extensive immunoreactivity. The results suggest that allostatins or allatostatin-like molecules are produced in neurosecretory cells of the brain and are delivered to the corpora allata through nervous connections and/or via haemolymph. Radiochemical measurements of juvenile hormone III biosynthesis by isolated corpora cardiaca-corpora allata complexes from adult G. bimaculatus have been used to demonstrate an in vitro sensitivity of these glands to allatostatin-1 from D. punctata. Allatostatin-1 is a relatively potent inhibitor of juvenile hormone III biosynthesis in corpora allata of both young adult females and males. In glands taken from 3-day virgin females, 50% inhibition of hormone biosynthesis is reached at ca. 3 nmol.l-1 allatostatin-1. The inhibitory action of allatostatin-1 is rapid, dose-dependent and reversible. Addition of 200 mumol.l-1 farnesol to the incubation medium prevents inhibition of juvenile hormone III biosynthesis by allatostatin-1. Juvenile hormone III biosynthesis by isolated corpora allata of 3-day female house crickets, A. domesticus, is also susceptible to inhibition by 1 mumol.l-1 allatostatin-1.

Age dependency and regulatory properties of juvenile hormone III biosynthesis in adult male crickets, Gryllus bimaculatus

The in vitro rate of juvenile hormone III (JH III) biosynthesis by corpora cardiaca-corpora allata complexes from paired and unpaired adult males of Gryllus bimaculatus is age-dependent. Both groups display a peak of juvenile hormone III production on day 2 after the imaginal moult, with the peak rate in paired males reaching about double that of unpaired animals. The juvenile hormone III synthesis then declines steadily in unpaired males, while in paired males additional phases of elevated rates occur. The juvenile hormone III titre in the haemolymph (as measured by radioimmunoassay) parallels the biosynthesis rate of juvenile hormone III for the first 4 days of adult life. Stimulation of the corpora allata with 200 μM farnesol in vitro produces no increase in juvenile hormone III production, but methyl farnesoate accumulates by a factor of 17 times over control values. Elevated Ca 2+ concentrations in the incubation medium stimulate the juvenile hormone III synthesis in vitro in a dose-dependent manner, while increased K + concentrations inhibit synthesis almost completely. Combined treatment with elevated Ca 2+ and exogenous application of 20 μM farnesol indicates no synergistic increase in methyl farnesoate accumulation, even when free calcium is increased 20-fold. Elevated K + combined with 200 μM farnesol leads to a stimulation of juvenile hormone III biosynthesis and especially methyl farnesoate accumulation. Male corpora allata, completely deprived of nervous connections during incubation or incubated together with detached brain or as intact brain-endocrine complexes, always show lower biosynthetic activity compared to control CC-CA complexes.

Strain-specificity of Galleria mellonella larvae to juvenilizing treatments

1. 1. The Warsaw and Florida strains of the wax moth, Galleria mellonella, are different in their sensitivity to juvenilizing treatments such as: chilling, application of ecdysone mimic (RH-5849) and juvenile hormone analogue (hydroprene), and implantation of brain or corpora cardiaca-corpora allata complex. 2. 2. The low sensitivity of the Florida strain larvae to these treatments results from low allatotropic activity of the brain of treated larvae and low sensitivity of corpora allata of this strain to allatotropin released from the brain. 3. 3. In the case of the Florida strain, the insects tissues had lower sensitivity to hydroprene and RH-5849 treatments compared to the Warsaw strain. 4. 4. In the haemolymph of chilled Warsaw strain larvae a small ecdysteroid peak, reaching a maximum of 28.0 ± 8.1 pg of 20-hydroecdysone per 1 μ1 of haemolymph was observed. 5. 5. This peak appeared 6 hr after chilling; it was absent in the haemolymph of chilled Florida strain larvae. 6. 6. The significance of this ecdysteroid peak in the induction of supernumerary larval moulting is discussed .

Isolation and identification of a new diuretic peptide from the tobacco hornworm, Manduca sexta

A 30-amino acid diuretic peptide was isolated from the corpora cardiaca-corpora allata complexes and, separately, from medial neurosecretory cells of the Sphingid moth, Manduca sexta. The peptide was found to have the following sequence, determined by automated Edman degradation and mass spectrometry: SFSVNPAVDILQHRYMEKV AQNNRNFLNRV-NH 2. We have named the peptide Mas-DP II. The peptide was synthesized and shown to possess diuretic activity in decapitated moths. Mas-DP II is related by sequence homology to a 41-amino acid diuretic peptide identified previously from M. sexta, and it belongs to the family of corticotropin releasing factor-like peptides.

Purification and characterization of eclosion hormone from the moth, Manduca sexta

The eclosion hormone (EH) of Manduca sexta is a 62 amino acid peptide which causes the behavioral and physiological changes that occur at ecdysis. EH was purified from the corpora cardiaca-corpora allata (CC-CA) complexes from pharate adult moths using acidic methanol extraction followed by two high performance liquid chromatography separation steps. One CC-CA complex was found to store about 3.5 ng of EH. Different techniques for estimating the molecular weight of the peptide, gel filtration chromatography and SDS-urea polyacrylamide electrophoresis, gave values of about 10 and 4 kD, respectively. Both were significantly different from the calculated molecular weight of 6813 dalton. The experimentally determined pI of the peptide was 4.8. Treatment of EH with various reagents showed that intact disulfide bridges are required for biological activity.

Biosynthesis and degradation of juvenile hormone in corpora allata and imaginal wing discs of Galleria mellonella (L.)

The rate of juvenile hormone (JH) biosynthesis by corpora allata-corpora cardiaca complex (CA/CC) during two last larval instars of Galleria mellonella was analysed. The rate of biosynthesis reaches maxima at the beginning of the VIth and VIIth instars. It is markedly reduced before the last larval ecdysis and after the first day of the last larval instar. After passing the second day of the last larval instar CA/CC exhibits again an increased ability for the biosynthesis of JH. The JH esterase activity in CA/CC is very low at the beginning of last larval instar and rapidly increases after the first day of this instar. Beginning on the second day of last larval instar the rate of JH hydrolysis is always higher than the rate of JH synthesis in CA/CC. It is concluded that the secretion of JH by CA/CC is possible until the second day of the last larval instar. After this, JH-acid can be supplied by CA/CC to peripheral tissues. The imaginal wing discs of mobile prepupa exhibit the ability to methylate JH-acid. It is concluded that some elevations of JH titre in G. mellonella haemolymph after the second day of VIIth instar are due in part to JH-acid methyltransferase activity in the imaginal discs.

Juvenile hormone degradation in brain and corpora cardiaca-corpora allata complex during the last larval instar ofGalleria mellonela (Lepidoptera, Pyralidae)

Time course analysis of juvenile hormone degradation in the brain and the corpora cardiaca-corpora allata complex shows that during the first two days of the last larval instar the juvenile hormone degradation is very low. Starting from the third day up to the seventh day a continuous increase of esterase activity is observed.

Control of neurosecretion in the moth Manduca sexta: physiological regulation of the eclosion hormone cells.

Metamorphosis in the moth Manduca sexta culminates with the secretion of the peptide eclosion hormone (EH), which triggers the stereotyped behavior of adult emergence (eclosion) from the pupal cuticle. In restrained but spontaneously behaving animals, the release of EH occurred shortly before the onset of subjective night (Fig. 3) and coincided with a depletion of EH from the neurohemal organs of the brain, the corpora cardiaca-corpora allata complex (CC-CA; Fig. 4). EH is produced by neurons within a bilaterally paired group of brain neurosecretory cells (Group Ia) which project to the CC-CA via the nervi corporis cardiaci- 1 + 2 (NCC-1 + 2; Fig. 1). Electrical stimulation of the NCC-1 + 2 caused a marked increase in the levels of EH secreted from isolated CC-CA (Fig. 2), while stimulation of the other nerves innervating the neurohemal organs did not. Electrical activity in the NCC-1 + 2 paralleled that of the cerebral neurosecretory cells (Fig. 1). Chronic extracellular recordings revealed a sudden increase in the tonic firing of several units within this nerve approximately 2 to 3 h before normal eclosion (Fig. 5), coincident with the release of EH bioactivity from the CC-CA (Fig. 6). The Group Ia neurons were electrically inactive on the day before eclosion (Day-1), but on the day of eclosion (Day 0) a subgroup of these cells exhibited both enhanced synaptic input and elevated rates of tonic firing during the normal time of EH release (Fig. 7). No significant differences in resting membrane potential or spike waveform characteristics were detected among the various subsets of Group Ia cells on either Day-1 or Day 0, while a significant increase in the resting input resistance was seen in the active subgroup on Day 0 (Fig. 8). This increase may be due to the regulatory effects of the steroid 20-hydroxyecdysone, which inhibits the release of EH and may act by preventing the synaptic activation of the EH neurons until the final day of adult development.

Lack of humoral control in calling and pheromone release by brain, corpora cardiaca, corpora allata and ovaries of the female gypsy moth, Lymantria dispar (L.)

Investigations into the physiological regulation of calling behaviour and pheromone release by the adult female gypsy moth, Lymantria dispar, showed that the brain, corpora cardiaca, corpora allata and ovaries play no significant endocrine role for either calling behaviour or pheromone release. Removal of corpora allata, corpora cardiaca-corpora allata complex and ovaries from last-instar larvae had no effect on calling behaviour nor on the pheromone release in the resulting moths. Severing the suboesophageal connectives had no effect on calling, but effectively eliminated pheromone release. Since severing nerves should not remove humoral output from the brain, the regulation on pheromone release appears neural.

Ecdysteroid regulation of the onset of cuticular melanization in allatectomized and Black mutant Manduca sexta larvae

The absence of juvenile hormone at the time of head cap slippage during the last-larval moult of the tabacco hornworm, Manduca sexta, causes deposition of premelanin granules into the outer regions of the newly forming endocuticle beginning 13 h later. These granules were found to contain an inactive phenoloxidase which becomes activated about 9 h later, 4 h before body melanization begins. The onset of melanization was not accelerated by melanization and reddish colouration hormone from Bombyx heads, extracts of pharate-adult corpora cardiaca or pharate-larval ventral nerve cords (sources of eclosion hormone), or extracts of pharate-larval suboesophageal ganglia or corpora cardiaca-corpora allata complexes. Instead the fall of the ecdysteroid titre to below 250 ng/ml 20-hydroxyecdysone equivalents appeared to be the cue that allowed melanization about 4.5 h later. Up to, but not after, this time both melanization and ecdysis could be delayed by exogenous 20-hydroxyecdysone in a dose-dependent fashion above 0.1 μg per larva. In vitro studies published elsewhere indicate that 20-hydroxyecdysone prevents the activation of the premelanin granules. Thus the granules can be deposited at the proper time in the newly forming endocuticle but their melanization is regulated by the declining ecdysteroid titre and it thus synchronized with other events occurring just before ecdysis.

Blood meal as a regulator of triacylglycerol synthesis in the haematophagous stable fly,Stomoxys calcitrans

Accumulation of triacylglycerol and glycogen reserves following meals of blood and/or sugar-water was investigated in the haematophagous stable fly,Stomoxys calcitrans. In the starved fly, triacylglycerol reserves appear to be utilized predominantly for energy requirements. When the starved flies were fed one meal of 1.0 M sucrose-water, they accumulated considerable amounts of glycogen but there was no increase in the triacylglycerol content. Starved flies fed one meal of blood accumulated large quantities of triacylglycerol but no glycogen; in those flies fed sugar-water and blood, glycogen and triacylglycerol accumulated. This study shows that the stable fly preferentially utilizes blood for triacylglycerol synthesis and sugar for glycogen synthesis. It is suggested that one or more factor(s) in the blood meal influences accumulation of triacylglycerol in this insect, possibly through an hormone from the corpora cardiaca-corpora allata complex.

Brain neurosecretion during ovarian development and after ovariectomy in adult Acheta domesticus L

Paraldehyde fuchsin (PAF) stained serial sections of the brain were examined for neurosecretory material (NSM) during adult ovarian development and in 10-day-old ovariectomized adult Acheta domesticus L. Type I neurosecretory cells of the pars intercerebralis were relatively low in NSM for the first 3 days of adult life, including the period during which vitellogenin synthesis and uptake are initiated. As mature oocytes accumulate after Day 4, NSM accumulates in the brain, reaching a peak by about Day 10. Ten-day-old adults ovariectomized as last instar larvae contained dramatically less brain NSM than intact controls, and injection of 0.48 μg of ecdysterone into ovariectomized crickets partially restored the brain to a state resembling that of intact animals. Peptides from the brains and corpora cardiaca-corpora allata complexes of intact and ovariectomized animals were separated by SDS-polyacrylamide gel electrophoresis and their PAF stainability was analyzed. Ovariectomy resulted in a decrease in the amounts of 12 brain peptides, but these showed little or no preferential staining with PAF. The possibility of regulatory interactions between the brain and ovaries is discussed.

Physiology of Pupal Ecdysis in the Tobacco Hornworm, Manduca Sexta

ABSTRACT Eclosion hormone activity was found in the brain and ventral ganglia of pharate pupae of Manduca sexta. No activity was detected in the corpora cardiaca-corpora allata complex. At the time of ecdysis the store of activity dropped by 50−75 % in the ventral cord whereas the hormone level in the brain remained unchanged. Also, larvae whose brains were removed at the wandering stage subsequently showed pupal ecdysis behaviour and also had essentially normal levels of hormonal activity in their blood at the start of the behaviour. It was concluded that at pupal ecdysis the hormone responsible for the initiation of the behaviour is released from the ventral nerve cord rather than from the brain. The chemical characteristics of the pharate pupal eclosion hormone were determined. The factors from the brain and ventral nerve cord were both active in a number of adult and pupal eclosion hormone bioassays. Both showed an apparent molecular weight of 8500 daltons and an isoelectric point of about 5−0, values essentially the same as that seen for the adult form of the hormone. We concluded that pupal ecdysis and adult eclosion are triggered by the same hormone but for the former it is released from the ventral nerve cord and, for the latter, from the brain. The choice of release site may depend on whether or not the release is under circadian control.