Retrocerebral Complex Research Articles

α-Solanine and α-Tomatine Affect the Retrocerebral Complexes of Tenebrio molitor and Zophobas atratus Beetles.

Presently, the European Commission is moving forward with a plan to reduce the use of chemical pesticides and increase the percentage of organic farming by 2030; this plan demands increased availability of biopesticides for organic farming. Glycoalkaloids are a class of molecules found in certain plants, including tomatoes and potatoes, which contain sugar and an alkaloid group. These compounds are known to have insecticidal properties, as they can act as natural defenses against insect pests. This study examined how a biological substance, glycoalkaloids, affects mortality and the retrocerebral complex of two beetle species, Tenebrio molitor and Zophobas atratus. More specifically, we focused on two glycoalkaloids, α-solanine and α-tomatine. Although these two insects belong to the same taxonomic family, they were not equally susceptible to these substances. In the mortality test, we observed that the T. molitor beetle seemed more susceptible, whereas the changes in the retrocerebral complex were more significant in the case of Z. atratus. In general, the effects vary between substances and insects, and changes in the retrocerebral complex may impair the reproduction of insects.

Adipokinetic hormone signaling regulates adult dehydration resistance in the migratory locust

Drought events have become more severe under climate change, and this can pose a major threat to the survival of various organisms. The molecular mechanisms involved in dehydration resistance are not well known. Here, adults of the migratory locust, Locusta migratoria, were subjected to food-mediated dehydration, and adipokinetic hormone (AKH) signaling was found to play a key role in regulating dehydration resistance. Specifically, dehydration shortened the lifespan, increased the body weight loss, and reduced the water loss rate in adult locusts. Global transcriptome profiles revealed variations in tissue-specific gene expression between dehydration-resistant locusts and normal locusts. Importantly, dehydration selection and exposure induced prominent expression of AKH genes in the retrocerebral complex of adult locusts. Furthermore, individual knockdown of AKH1, AKH2, or AKH receptor (AKHR) accelerated water loss and shortened the lifespan of adult locusts under dehydration conditions, and trehalose supplementation ameliorated the negative effects caused by interference with AKH or AKHR. These findings demonstrated that AKH/AKHR signaling-dependent trehalose metabolism plays a crucial role in regulating locust dehydration resistance and thus provide novel insights into the regulatory mechanism underlying drought resistance.

Neuropeptides as potential modulators of behavioral transitions in the ant Cataglyphis nodus.

Age-related behavioral plasticity is a major prerequisite for the ecological success of insect societies. Although ecological aspects of behavioral flexibility have been targeted in many studies, the underlying intrinsic mechanisms controlling the diverse changes in behavior along the individual life history of social insects are not completely understood. Recently, the neuropeptides allatostatin-A, corazonin, and tachykinin have been associated with the regulation of behavioral transitions in social insects. Here, we investigated changes in brain localization and expression of these neuropeptides following major behavioral transitions in Cataglyphis nodus ants. Our immunohistochemical analyses in the brain revealed that the overall branching pattern of neurons immunoreactive (ir) for the three neuropeptides is largely independent of the behavioral stages. Numerous allatostatin-A- and tachykinin-ir neurons innervate primary sensory neuropils and high-order integration centers of the brain. In contrast, the number of corazonergic neurons is restricted to only four neurons per brain hemisphere with cell bodies located in the pars lateralis and axons extending to the medial protocerebrum and the retrocerebral complex. Most interestingly, the cell-body volumes of these neurons are significantly increased in foragers compared to freshly eclosed ants and interior workers. Quantification of mRNA expression levels revealed a stage-related change in the expression of allatostatin-A and corazonin mRNA in the brain. Given the presence of the neuropeptides in major control centers of the brain and the neurohemal organs, these mRNA-changes strongly suggest an important modulatory role of both neuropeptides in the behavioral maturation of Cataglyphis ants.

A possible role of tachykinin-related peptide on an immune system activity of mealworm beetle, Tenebrio molitor L.

Tachykinin-related peptides (TRPs) are important neuropeptides. Here we show that they affect the insect immune system, especially the cellular response. We also identify and predict the sequence and structure of the tachykinin-related peptide receptor (TRPR) and confirm the presence of expression of gene encoding TRPR on Tenebrio molitor haemocytes.After application of the Tenmo-TRP-7 in T. molitor the number of circulating haemocytes increased and the number of haemocytes participating in phagocytosis of latex beads decreased in a dose- and time-dependent fashion. Also, Tenmo-TRP-7 affects the adhesion ability of haemocytes. Six hours after injection of Tenmo-TRP-7, a decrease of haemocyte surface area was observed under both tested Tenmo-TRP-7 concentrations (10−7 and 10−5 M). The opposite effect was reported 24 h after injection, which indicates that the influence of Tenmo-TRP-7 on modulation of haemocyte behaviour differs at different stages of stress response. Tenmo-TRP-7 application also resulted in increased phenoloxidase activity 6 and 24 h after injection.The assessment of DNA integrity of haemocytes showed that the injection of Tenmo-TRP-7 at 10−7 M led to a decrease in DNA damage compared to control individuals. This effect was only visible 6 h after Tenmo-TRP-7 application. After 24 h, Tenmo-TRP-7 injection increased DNA damage.We also confirmed the expression of immune-related genes in nervous tissue of T. molitor. Transcripts for genes encoding receptors participating in pathogen recognition processes and antimicrobial peptides were detected in T. molitor brain, retrocerebral complex and ventral nerve cord. These results may indicate a role of the insect nervous system in pathogen recognition and modulation of immune response similar to vertebrates.Taken together, our results support the notion that tachykinin-related peptides probably play an important role in the regulation of the insect immune system. Moreover, some resemblances with action of tachykinin-related peptides and substance P showed that insects can be potential model organisms for analysis of hormonal regulation of conserved innate immune mechanisms.

A Novel Head Capsule Labial Gland Lobe in the Black Field Cricket (Orthoptera: Gryllidae).

We describe a pair of labial gland lobes on either side of the retrocerebral complex in the head of the Australian black field cricket, Teleogryllus commodus Walker. As the retrocerebral complex includes the corpora cardiaca and corpora allata, hormones secreted by these glands can be absorbed by these lobes. These lobes of the labial gland are connected to the thoracic lobes via a relatively long duct that enters the main duct draining the thoracic lobes. Measurement of the flow rate of dye from head to thorax in the ducts is rapid, suggesting that these glands may serve as a transport system into the thoracic region. Both serotonin and adipokinetic hormone are shown to be present in the lobes near the retrocerebral complex and the ducts of the thoracic lobes, but whether this connection between the head and thorax acts as a hormone transporter is still unclear.

Identification, Localization in the Central Nervous System and Novel Myostimulatory Effect of Allatostatins in Tenebrio molitor Beetle.

Allatostatins (ASTs) are pleiotropic insect neuropeptides that are potent myoinhibitors of muscle contractions. In this study, we identified and immunolocalized peptides from the MIP/AST and PISCF/AST families in the nervous system of a model beetle, Tenebrio molitor. Neurons containing MIPs were immunolocalized in the brains of adults and the ventral nerve cords of larvae, pupae and imagines of this species as well as in the retrocerebral complex. PISCFs were immunolocalized in the ventral nerve cord of all stages as well as the brain of the adult beetle. Faint signals were also observed in the corpus allatum but not in the corpus cardiacum. The results allowed us to deduce the sequences of three neuropeptides belonging to MIP/ASTs, Tenmo-MIP4—NWGQFGXWa, Tenmo-MIP5—SKWDNFRGSWa and Tenmo-MIP6—EPAWSNLKGIWa, and one peptide from the PISCF/AST family, QSRYXQCYFNPISCX. Furthermore, we showed for the first time myostimulatory action of endogenous MIP/ASTs. Tenmo-MIP5 caused dose-dependent stimulation of the contractile activity of the beetle oviduct muscles, showing a sigmoidal curve up to 81.20% at the 10−8 M concentration, and the EC50 value for the myostimulatory effect of this peptide was 8.50 × 10−12 M. This is the first report of myostimulatory action of an endogenous myoinhibitory peptide in insect muscles.

Enhanced Coverage of Insect Neuropeptides in Tissue Sections by an Optimized Mass-Spectrometry-Imaging Protocol.

Mass spectrometry imaging (MSI) of neuropeptides has become a well-established method with the ability to combine spatially resolved information from immunohistochemistry with peptidomics information from mass spectrometric analysis. Several studies have conducted MSI of insect neural tissues; however, these studies did not detect neuropeptide complements in manners comparable to those of conventional peptidomics. The aim of our study was to improve sample preparation so that MSI could provide comprehensive and reproducible neuropeptidomics information. Using the cockroach retrocerebral complex, the presented protocol produces enhanced coverage of neuropeptides at 15 μm spatial resolution, which was confirmed by parallel analysis of tissue extracts using electrospray-ionization MS. Altogether, more than 100 peptide signals from 15 neuropeptide-precursor genes could be traced with high spatial resolution. In addition, MSI spectra confirmed differential prohormone processing and distinct neuropeptide-based compartmentalization of the retrocerebral complex. We believe that our workflow facilitates incorporation of MSI in neuroscience-related topics, including the study of complex neuropeptide interactions within the CNS.

Myotropic activity and immunolocalization of selected neuropeptides of the burying beetle Nicrophorus vespilloides (Coleoptera: Silphidae).

Burying beetles (Nicrophorus sp.) are necrophagous insects with developed parental care. Genome of Nicrophorus vespilloides has been recently sequenced, which makes them interesting model organism in behavioral ecology. However, we know very little about their physiology, including the functioning of their neuroendocrine system. In this study, one of the physiological activities of proctolin, myosuppressin (Nicve-MS), myoinhibitory peptide (Trica-MIP-5) and the short neuropeptide F (Nicve-sNPF) in N. vespilloides have been investigated. The tested neuropeptides were myoactive on N. vespilloides hindgut. After application of the proctolin increased hindgut contraction frequency was observed (EC50 value was 5.47 × 10-8 mol/L). The other tested neuropeptides led to inhibition of N. vespilloides hindgut contractions (Nicve-MS: IC50 = 5.20 × 10-5 mol/L; Trica-MIP-5: IC50 = 5.95 × 10-6 mol/L; Nicve-sNPF: IC50 = 4.08 × 10-5 mol/L). Moreover, the tested neuropeptides were immunolocalized in the nervous system of N. vespilloides. Neurons containing sNPF and MIP in brain and ventral nerve cord (VNC) were identified. Proctolin-immunolabeled neurons only in VNC were observed. Moreover, MIP-immunolabeled varicosities and fibers in retrocerebral complex were observed. In addition, our results have been supplemented with alignments of amino acid sequences of these neuropeptides in beetle species. This alignment analysis clearly showed amino acid sequence similarities between neuropeptides. Moreover, this allowed to deduce amino acid sequence of N. vespilloides proctolin (RYLPTa), Nicve-MS (QDVDHVFLRFa) and six isoforms of Nicve-MIP (Nicve-MIP-1-DWNRNLHSWa; Nicve-MIP-2-AWQNLQGGWa; Nicve-MIP-3-AWQNLQGGWa; Nicve-MIP-4-AWKNLNNAGWa; Nicve-MIP-5-SEWGNFRGSWa; Nicve-MIP-6- DPAWTNLKGIWa; and Nicve-sNPF-SGRSPSLRLRFa).

Neuropeptide Mapping of Dimmed Cells of Adult Drosophila Brain.

Neuropeptides are structurally highly diverse messenger molecules that act as regulators of many physiological processes such as development, metabolism, reproduction or behavior in general. Differentiation of neuropeptidergic cells often corresponds with the presence of the transcription factor DIMMED. In the central nervous system of the fruit fly Drosophila melanogaster, DIMMED commonly occurs in neuroendocrine neurons that release peptides as neurohormones but also in interneurons with complex branching patterns. Fly strains with green fluorescence protein (GFP)-expressing dimmed cells make it possible to systematically analyze the processed neuropeptides in these cells. In this study, we mapped individual GFP-expressing neurons of adult D. melanogaster from the dimmed (c929)>GFP line. Using single cell mass spectrometry, we analyzed 10 types of dimmed neurons from the brain/gnathal ganglion. These cells included neuroendocrine cells with projection into the retrocerebral complex but also a number of large interneurons. Resulting mass spectra not only provided comprehensive data regarding mature products from 13 neuropeptide precursors but also evidence for the cellular co-localization of neuropeptides from different neuropeptide genes. The results can be implemented in a neuroanatomical map of the D. melanogaster brain. Graphical Abstract ᅟ.

Neuropeptides in the desert ant Cataglyphis fortis: Mass spectrometric analysis, localization, and age-related changes.

Cataglyphis desert ants exhibit an age-related polyethism, with ants performing tasks in the dark nest for the first ∼4 weeks of their adult life before they switch to visually based long-distance navigation to forage. Although behavioral and sensory aspects of this transition have been studied, the internal factors triggering the behavioral changes are largely unknown. We suggest the neuropeptide families allatostatin A (AstA), allatotropin (AT), short neuropeptide F (sNPF), and tachykinin (TK) as potential candidates. Based on a neuropeptidomic analysis in Camponotus floridanus, nano-LC-ESI MS/MS was used to identify these neuropeptides biochemically in Cataglyphis fortis. Furthermore, we show that all identified peptide families are present in the central brain and ventral ganglia of C. fortis whereas in the retrocerebral complex only sNPF could be detected. Immunofluorescence staining against AstA, AT, and TK in the brain revealed arborizations of AstA- and TK-positive neurons in primary sensory processing centers and higher order integration centers, whereas AT immunoreactivity was restricted to the central complex, the antennal mechanosensory and motor center, and the protocerebrum. For artificially dark-kept ants, we found that TK distribution changed markedly in the central complex from days 1 and 7 to day 14 after eclosion. Based on functional studies in Drosophila, this age-related variation of TK is suggestive of a modulatory role in locomotion behavior in C. fortis. We conclude that the general distribution and age-related changes in neuropeptides indicate a modulatory role in sensory input regions and higher order processing centers in the desert ant brain. J. Comp. Neurol. 525:901-918, 2017. © 2016 Wiley Periodicals, Inc.

Notable plesiomorphies and notable specializations: Head structure of the primitive “tongue moth” Acanthopteroctetes unifascia (lepidoptera: Acanthopteroctetidae)

The Acanthopteroctetidae are one of the first-originated family-group lineages within "tongue moths" (Lepidoptera-Glossata). The purpose of this study is to provide a comprehensive account (based on whole mount preparations, serial sections, and Scanning electron microscopy) of the cephalic structure of an adult exemplar of the family, to supplement the sparse available information. Notable plesiomorphies include the retention of frontal retractors of the narrow labrum, a high supraocular index linked to strong development of cranio-mandibular ad- and abductors, and perhaps the unusually short but still coilable (just ca. 1.5 turns) galeal "tongue." Notable specializations (probably mostly family autapomorphies) include a complement of large sensilla placodea on the male antennae, an apical attachment of the long dorsal tentorial arm to the cranium, an extreme reduction of the single-segmented labial palps, a particularly strong subgenal bridge and a surface structure of near-parallel ridges on the ommatidial corneae. The presence of sizable saccular mandibular (type 1) glands opening into the adductor apodeme is unexpected, no counterparts being known from neighboring taxa. The same is true for ventral salivarium dilator muscles originating on the prelabium; and tentatively suggested to be homologues of the extrinsic palp flexors (the insertion shift being related to loss of original function due to palp reduction), rather than to the ventral salivarium muscles of more basal insects. A complete "deutocerebral loop"' may or may not be developed, as is true for a mutual appression of the optic lobe and circumoesophageal connective/suboesophageal ganglion, enclosing the anterior tentorial arm between them; a suboesophageal innervation of the retrocerebral complex was not observed. No characters bearing on the monophyly of the Coelolepida were identified. The scapo-pedicellar articulation with a scapal process and a smooth intercalary sclerite is reminiscent of conditions in Neopseustidae, but remains debatable as a synapomorphy of the two families.

Insulin-like and testis ecdysiotropin neuropeptides are regulated by the circadian timing system in the brain during larval–adult development in the insect Rhodnius prolixus (Hemiptera)

Insulin-like peptides (ILPs) regulate numerous functions in insects including growth, development, carbohydrate metabolism and female reproduction. This paper reports the immunohistochemical localization of ILPs in brain neurons of Rhodnius prolixus and their intimate associations with the brain circadian clock system. In larvae, three groups of neurons in the protocerebrum are ILP-positive, and testis ecdysiotropin (TE) is co-localized in two of them. During adult development, the number of ILP groups increased to four. A blood meal initiates transport and release of ILPs, indicating that release is nutrient dependent. Both production and axonal transport of ILPs continue during adult development with clear cytological evidence of a daily rhythm that closely correlates with the daily rhythm of ILPs release from brains in vitro. The same phenomena were observed with TE previously. Double labeling for ILPs and pigment dispersing factor (PDF) (contained in the brain lateral clock cells, LNs) revealed intimate associations between axons of the ILP/TE cells and PDF-positive axons in both central brain and retrocerebral complex, revealing potential neuronal pathways for circadian regulation of ILPs and TE. Similar close associations were found previously between LN axons and axons of the brain neurons producing the neuropeptide prothoracicotropic hormone. Thus, the brain clock system controls rhythmicity in multiple brain neurohormones. It is suggested that rhythms in circulating ILPs and TE act in concert with known rhythms of circulating ecdysteroids in both larvae and adults to orchestrate the timing of cellular responses in diverse tissues of the animal, thereby generating internal temporal order within it.

Projection of FMRFamide-like neuropeptide-producing neurosecretory cells from silkworm brain into ventral nerve cord and retrocerebral complex

AbstractUsing immunostaining methodology, we traced the axonal projection of FMRFamide (Phe-Met-Arg-Phe-NH2)-like immunoreactive (LI) medial neurosecretory cells (MNCs) and lateral neurosecretory cells (LNCs) from the brain into the ventral nerve cord (VNC) and retrocerebral complex inBombyx mori(L.) (Lepidoptera: Bombycidae). Of the seven pairs of FMRFamide-LI MNCs, one pair extended its axons from the brain pars intercerebralis into the VNC ipsilateral connective where they appeared to terminate. The axons of the remaining MNCs ran through decussation in the brain median region and contralateral nervi corporis cardiaci (NCC) I out of the brain, and eventually innervated the contralateral corpus cardiacum (CC). Axons from the single pair of FMRFamide-LI LNCs projected into the ipsilateral NCC II fused with NCC I without decussation in the brain, and finally terminated in the CC. These results suggest that transport of the FMRFamide-like neuropeptide from may be related to the modulation of functions such as gut contraction in MNCs terminating in the VNC, and regulation of production and/or secretion of specific hormones such as juvenile hormone in MNCs and LNCs terminating in the CC.

Primary structure of an adipokinetic neuropeptide from the rhinoceros beetle, Oryctes rhinoceros L (Coleoptera: Dynastidae).

Neuropeptides play an important role in cellular communication in vertebrates. This is also true for insects in which many physiological, developmental and behavioral processes are affected by neuropeptides produced in neurosecretory cells of the retrocerebral complex. Small neuropeptides of the adipokinetic hormone/red pigment concentrating hormone family (AKH/RPCH) are one of the important groups of peptides that regulate physiological homeostasis. The present investigation was carried out to elucidate the primary structure of adipokinetic neuropeptides in the rhinoceros beetle, O. rhinoceros. In the present investigation, an adipokinetic neuropeptide from the coconut pest, Oryctes rhinoceros was isolated from corpora cardiaca by HPLC; the chromatographic fractions were tested for adipokinetic activity in the plant bug, Iphita limbata in vivo. Two UV absorbance peaks were found to be significantly active in elevating haemolymph lipid levels. MALDI-MS analysis of the extract indicated that the molecular mass, 1003.70 Da is similar to the already known AKH from another beetle, Melolontha melolontha. MALDI-MS/MS analysis confirmed that its primary structure is exactly similar to the structure reported for the Melme-AKH (pE-L-N-Y-S-P-D-W-NH2). The findings suggest that the distribution of AKH peptides has shown that there exists a taxonomic order or family specificity. This data can be used as additional information to aid in the construction of phylogenetic trees by means of computer programme and protein parsimony algorithms.

Infection dynamics of western equine encephalomyelitis virus (Togaviridae: Alphavirus) in four strains of Culex tarsalis (Diptera: Culicidae): an immunocytochemical study.

BACKGROUND: Vector competence describes the efficiency with which vector arthropods become infected with and transmit pathogens and depends on interactions between pathogen and arthropod genetics as well as environmental factors. For arbovirus transmission, the female mosquito ingests viremic blood, the virus infects and replicates in midgut cells, escapes from the midgut, and disseminates to other tissues, including the salivary glands. Virus-laden saliva is then injected into a new host. For transmission to occur, the virus must overcome several "barriers", including barriers to midgut infection and/or escape and salivary infection and/or escape. By examining the spatial/temporal infection dynamics of Culex tarsalis strains infected with western equine encephalomyelitis virus (WEEV), we identified tissue tropisms and potential tissue barriers, and evaluated the effects of viral dose and time postingestion. METHODS: Using immunostained paraffin sections, WEEV antigens were tracked in four Cx. tarsalis strains: two recently colonized California field strains - Coachella Valley, Riverside County (COAV) and Kern National Wildlife Refuge (KNWR); and two laboratory strains selected for WEEV susceptibility (high viremia producer, HVP), and WEEV resistance (WR). RESULTS AND CONCLUSIONS: Tissues susceptible to WEEV infection included midgut epithelium, neural ganglia, trachea, chorionated eggs, and salivary glands. Neuroendocrine cells in the retrocerebral complex were occasionally infected, indicating the potential for behavioral effects. The HVP and COAV strains vigorously supported viral growth, whereas the WR and KNWR strains were less competent. Consistent with earlier studies, WEEV resistance appeared to be related to a dose-dependent midgut infection barrier, and a midgut escape barrier. The midgut escape barrier was not dependent upon the ingested viral dose. Consistent with midgut infection modulation, disseminated infections were less common in the WR and KNWR strains than in the HVP and COAV strains. Once the virus disseminated from the midgut, all strains were able to develop salivary gland infections. The possible roles of observed pathology will be discussed in a subsequent paper.

Neuropeptides associated with the central nervous system of the cabbage root fly, Delia radicum (L)

The peptidome of the central nervous system of adult cabbage root fly, Delia radicum (L) was investigated using matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). Over twenty neuropeptides were identified from three different tissue sources, the combined brain/suboesophageal ganglion (SOG), the retrocerebral complex, and the thoracic-abdominal ganglion (TAG). A number of peptides were identified in all three tissues, including allatostatins, short neuropeptide F-like peptides, corazonin, a pyrokinin, and a myosuppressin. Adipokinetic hormone was restricted to the retrocerebral complex. Other peptides, including FMRFamides and sulfakinins were detected only in the brain/SOG and TAG. Some peptides, notably myoinhibitory peptides and tachykinins, which have been identified in other fly species, were not detected in any tissue sample. This study has structurally characterized for the first time, the neuropeptides from adult D. radicum.

Allatotropin expression during the development of the fourth instar larvae of the kissing-bug Triatoma infestans (Klüg)

Allatotropin (AT) is a neuropeptide originally isolated from the brain of Manduca sexta and then characterized in several insect species. It acts as a neurohormone, as well as a neuromodulator. While it was primarily characterized on the basis of its ability to stimulate the secretion of juvenile hormones, it was also found that it acts as a cardioaccelerator and myostimulator. The presence of AT in IV instar larvae of T. infestans was previously described at the level of the Malpighian tubules. In the present study we report the presence of the peptide at the level of the brain, retrocerebral complex, as well as in the anterior midgut and aorta. The presence of AT at the corpora allata suggests that the peptide is acting on the gland during the first days of the moulting cycle. Neural processes at the level of the aorta and the anterior midgut suggests that, like in adults, the hormone is acting as a cardioaccelerator and myostimulator. The peptide was also found in open-type cells of the midgut. Finally the presence of allatotropic neurons in the optical lobe of the brain suggests that as in other species, the peptide is related with the control of circadian rhythms.

Identification of Myotropic Neuropeptides from the Brain and Corpus Cardiacum-Corpus Allatum Complex of the Beetle,Zophobas atratus

The neuropeptide profiles of the two major neuro-endocrinological organs, brain and retrocerebral complex corpus cardiacum-corpus allatum (CC/CA) of adult beetles, Zophobas atratus Fabricius (Coleoptera:Tenebrionidae) were analyzed by a combination of high performance liquid chromatography (HPLC) and matrix-assisted laser desorption ionization time of flight tandem mass spectrometry (MALDI TOF/TOF MS). The homological semi-isolated heart bioassay was used to screen HPLC fractions for myotropic activity in tissues, revealing several cardiostimulatory and cardioinhibitory factors from both the brain and CC/CA. Analysis of HPLC fractions by MALDI-TOF MS identified seven mass ions that could be assigned to other known peptides: leucomyosuppressin (LMS), Tribolium castaneum pyrokinin 2, sulfakinin 1, myoinhibitory peptide 4, a truncated NVP-like peptide, Tenebrio molitor AKH and crustacean cardioactive peptide. In addition, two novel peptides, myosuppressin (pEDVEHVFLRFa), which differs from LMS by one amino acid (E for D at position 4) and pyrokinin-like peptide (LPHYTPRLa) were also identified. To establish cardioactive properties of some of the identified peptides, chemical synthesis was carried out and their activities were tested using the heart bioassay.

Physiological characterization of the cold-shock-induced humoral factor for wing color-pattern changes in butterflies

Butterfly wing color patterns can be modified by the application of temperature shock to pupae immediately after pupation, which has been attributed to a cold-shock-induced humoral factor called cold-shock hormone (CSH). Here, we physiologically characterized CSH and pharmacological action of tungstate, using a nymphalid butterfly Junonia orithya. We first showed that the precise patterns of modification were dependent on the time-point of the cold-shock treatment after pupation, and confirmed that the modification properties induced in a cold-shocked pupa were able to be transferred to another pupa in a parabiosis experiment. Cold-shock application after removal of the head and prothorax together still produced modified wings, excluding major involvement of the brain–retrocerebral neuroendocrine complex. Furthermore, tungstate injection induced modifications even in individuals whose head and prothorax were removed. Importantly, transplantation of tracheae isolated from cold-shocked pupae induced modifications in the recipient wings. We identified a chemical peak in hemolymph of the cold-shocked individuals using HPLC, which corresponded to dopamine, and demonstrated that dopamine and its related biogenic amines have ability to induce small color-pattern changes. Taken together, the present study suggests that CSH is likely to be secreted from trachea-associated endocrine cells upon cold-shock treatment and that tungstate may change color patterns via its direct action on wings.

Peptidomic survey of the locust neuroendocrine system

Neuropeptides are important controlling agents in animal physiology. In order to understand their role and the ways in which neuropeptides behave and interact with one another, information on their time and sites of expression is required. We here used a combination of MALDI-TOF and ESI-Q-TOF mass spectrometry to make an inventory of the peptidome of different parts (ganglia and nerves) of the central nervous system from the desert locust Schistocerca gregaria and the African migratory locust Locusta migratoria. This way, we analysed the brain, suboesophageal ganglion, retrocerebral complex, stomatogastric nervous system, thoracic ganglia, abdominal ganglia and abdominal neurohemal organs. The result is an overview of the distribution of sixteen neuropeptide families, i.e. pyrokinins, pyrokinin-like peptides, periviscerokinins, tachykinins, allatotropin, accessory gland myotropin, FLRFamide, (short) neuropeptide F, allatostatins, insulin-related peptide co-peptide, ion-transport peptide co-peptide, corazonin, sulfakinin, orcokinin, hypertrehalosaemic hormone and adipokinetic hormones (joining peptides) throughout the locust neuroendocrine system.