Bursicon is the final neurohormone released at the end of the molting cycle. It triggers the sclerotization (tanning) of the insect cuticle. Until now, its existence has been verified only by bioassays. In an attempt to identify this... more
Bursicon is the final neurohormone released at the end of the molting cycle. It triggers the sclerotization (tanning) of the insect cuticle. Until now, its existence has been verified only by bioassays. In an attempt to identify this important neurohormone, bursicon was purified from homogenates of 2,850 nerve cords of the cockroach Periplaneta americana by using high performance liquid chromatography technology and two‐dimensional gel electrophoresis. Bursicon bioactivity was found in four distinct protein spots at approximately 30 kDa between pH 5.3 and 5.9. The protein of one of these spots at pH 5.7 was subsequently microsequenced, and five partial amino acid sequences were retrieved. Evidence is presented that two of these sequences are derived from bursicon. Antibodies raised against the two sequences labeled bursicon‐containing neurons in the central nervous systems of P. americana. One of these antisera labeled bursicon‐containing neurons in the crickets Teleogryllus commodus and Gryllus bimaculatus, and the moth Manduca sexta. A cluster of four bilaterally paired neurons in the brain of Drososphila melanogaster was also labeled. In addition, this antiserum detected three spots corresponding to bursicon in Western blots of two‐dimensional gels. The 12‐amino acid sequence detected by this antiserum, thus, seems to be conserved even among species that are distantly related. J. Comp. Neurol. 452:163–177, 2002. © 2002 Wiley‐Liss, Inc.
Research Interests: Biology, Immunohistochemistry, Medicine, Drosophila, Neuropeptides, and 15 moreAnimals, Central Nervous System, Medical Physiology, High Pressure Liquid Chromatography, Antiserum, Larva, Manduca, Species Specificity, Amino Acid Sequence, Comparative Neurology, Neurosciences, Cockroach, Gryllidae, Ecdysis, and Neuropeptide
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In the crickets Gryllus bimaculatus and Gryllus campestris, the two intrinsic antennal muscles in the scape (first antennal segment) control antennal movements in the horizontal plane. Of the 17 excitatory antennal motoneurons, three... more
In the crickets Gryllus bimaculatus and Gryllus campestris, the two intrinsic antennal muscles in the scape (first antennal segment) control antennal movements in the horizontal plane. Of the 17 excitatory antennal motoneurons, three motoneurons, two fast and one slow, can be stimulated selectively and their effect on muscle contraction, i.e. antennal movement, measured. Simultaneously, either a common inhibitor (CI) neuron
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ABSTRACT
Research Interests: Biology, Medicine, Anatomy, Brain, Anoxia, and 8 moreCapillaries, Animals, Fishes, Heart rate, Respiration, Time Factors, Respiration physiology, and Dilatation
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Research Interests: Biology, Medicine, Interneuron, Biological Sciences, Anatomy, and 15 moreBrain, Female, Animals, Male, Mechanoreceptors, Insect, Conduction Velocity, Interneurons, Experimental Biology, Gryllidae, Extremities, Excitatory Postsynaptic Potentials, Gryllus bimaculatus, Medical and Health Sciences, and Electric stimulation
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ABSTRACT. Males of the cricket, Gryllus campestris L. (Orthoptera: Gryllidae), displayed three different diel patterns in the timing of their calling song: 55% of all males investigated were dark‐active, 25% light‐active and 20%... more
ABSTRACT. Males of the cricket, Gryllus campestris L. (Orthoptera: Gryllidae), displayed three different diel patterns in the timing of their calling song: 55% of all males investigated were dark‐active, 25% light‐active and 20% light‐and‐dark‐active. Dark‐active males continued to stridulate in both constant darkness (DD) and constant light (LL) during the subjective night, with a circadian period usually shorter (in DD) or longer (in LL) than 24h. Light‐active males were mainly silent in DD but showed a circadian rhythm in LL, though with a 180° phase shift, i.e. activity during subjective night. This suggests that daytime activity has developed from nocturnal activity by a mechanism which prevents stridulation during darkness, and that both patterns are driven by the same endogenous clock. In the light‐and‐dark‐active males some stridulation takes place during darkness, so dark inhibition is not complete. Such incomplete inhibition seemed to occur only in highly active animals. The three diel distribution patterns of the calling song are discussed in relation to sharing the chances of attracting females.
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Research Interests: Biology, Immunohistochemistry, Drosophila melanogaster, Medicine, Brain, and 15 moreCircadian Rhythm, Female, Animals, Male, Central Nervous System, Monoclonal Antibodies, Medical Physiology, Neurons, Western blot, Molecular weight, Monoclonal Antibody, Neuropil, Gryllidae, medulla, and Distributed Networks
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Mechanical stimulation of the compound eye of the cricketGryllus campestris induces an eye cleaning response which involves coordinated movements of the head and the forelegs. Interommatidial bristles and campaniform sensilla provide the... more
Mechanical stimulation of the compound eye of the cricketGryllus campestris induces an eye cleaning response which involves coordinated movements of the head and the forelegs. Interommatidial bristles and campaniform sensilla provide the sensory input for the behavior. The axons of these receptors project through a sidebranch of the nervus tegumentarius into the suboesophageal and prothoracic ganglion. Recordings from this nerve
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During posteclosion, insects undergo sequential processes of wing expansion and cuticle tanning. Bursicon, a highly conserved neurohormone implicated in regulation of these processes, was characterized recently as a heterodimeric cystine... more
During posteclosion, insects undergo sequential processes of wing expansion and cuticle tanning. Bursicon, a highly conserved neurohormone implicated in regulation of these processes, was characterized recently as a heterodimeric cystine knot protein in Drosophila melanogaster. Here we report the predicted precursor sequences of bursicon subunits (Masburs and Maspburs) in the moth Manduca sexta. Distinct developmental patterns of mRNA transcript and subunit‐specific protein labeling of burs and pburs as well as crustacean cardioactive peptide in neurons of the ventral nervous system were observed in pharate larval, pupal, and adult stages. A subset of bursicon neurons located in thoracic ganglia of larvae expresses ecdysis‐triggering hormone (ETH) receptors, suggesting that they are direct targets of ETH. Projections of bursicon neurons within the CNS and to neurohemal secretory sites are consistent with both central signaling and circulatory hormone functions. Intrinsic cells of the corpora cardiaca contain pburs transcripts and pburs‐like immunoreactivity, whereas burs transcripts and burs‐like immunoreactivity were absent in these cells. Recombinant bursicon induces both wing expansion and tanning, whereas synthetic eclosion hormone induces only wing expansion. J. Comp. Neurol. 506:759–774, 2008. © 2007 Wiley‐Liss, Inc.
Research Interests: Biology, Tobacco, Immunohistochemistry, Drosophila melanogaster, Cell Biology, and 15 moreMedicine, Internal Medicine, Sequence alignment, Animals, Medical Physiology, Neurons, Manduca, Amino Acid Sequence, Sphingidae, Comparative Neurology, Molting, Neurosciences, Ecdysis, Molecular Sequence Data, and Tissue distribution
Neuronal projections from one optic lobe to other parts of the brain were stained in the cricket Gryllus campestris using the cobalt sulphide technique and Timm's sulphide-silver method. The results are: Four tracts directly... more
Neuronal projections from one optic lobe to other parts of the brain were stained in the cricket Gryllus campestris using the cobalt sulphide technique and Timm's sulphide-silver method. The results are: Four tracts directly connect the medulla with the lobula and medulla of the contralateral optic lobe. Direct medullar projections end mainly in the non-glomerular neuropile of the protocerebrum, but also penetrate the calyx of the mushroom bodies, pons and central body in small numbers. A few somata which send fibres into the medulla lie in the pars intercerebralis, in the protocerebrum ventral to the opposite beta-lobe, the outer margin of the medulla of the contralateral optic lobe and between deuto- and tritocerebrum. The anatomical and physiological relevance of the stained connections is discussed.
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We are examining the roles that specific gene expression play in development and behavior in the nervous system of the American lobster, Homarus americarus. In particular, we have isolated genomic DNA sequences that encompass several... more
We are examining the roles that specific gene expression play in development and behavior in the nervous system of the American lobster, Homarus americarus. In particular, we have isolated genomic DNA sequences that encompass several putative lobster genes— one possibly encoding a receptor for the steroid molting hormone, 20-hydroxyecdysone, and at least one homologous to the family of mammalian genes encoding the biopterin-dependent amine hydroxylases (tryptophan hydroxylase, tyrosine hydroxylase, and phenylalanine hydroxylase). Tryptophan hydroxylase is the rate-limiting enzyme for the synthesis of serotonin, a developmentally regulated lobster neurohormone. The control of expression of these genes in individual lobster neurons can be assayed by in situ hybridization and could provide insights into the linkage between behavior, development, and gene expression in this organism.
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SummaryIn the crickets, Gryllus campestris and Gryllus bimaculatus, the innervation of the dorso-ventral neck muscles M62, M57, and M59 was examined using cobalt staining via peripheral nerves and electrophysiological methods. M62 and M57... more
SummaryIn the crickets, Gryllus campestris and Gryllus bimaculatus, the innervation of the dorso-ventral neck muscles M62, M57, and M59 was examined using cobalt staining via peripheral nerves and electrophysiological methods. M62 and M57 are each innervated by two motoneurons in the suboesophageal ganglion. The four motoneurons project into the median nerve to bifurcate into the transverse nerves of both sides. M62 and M57 are the only neck muscles innervated via this route. These bifurcating axon-projections are identical to those of the spiracular motoneurons in the prothoracic ganglion innervating the opener and closer muscle of the first thoracic spiracle in the cricket. The morphology of their branching pattern is described. The neck muscle M57 and the opener muscle of the first thoracic spiracle are additionally innervated by one mesothoracic motoneuron each, with similar morphology. These results suggest, that in crickets, the neck muscles M57 and M62 are homologous to spiracular muscles in the thoracic segments. The two neck muscles M62 and M59 (the posterior neighbour of M57) receive projections from a prothoracic dorsal unpaired median (DUM) neuron that also innervates dorsal-longitudinal neck muscles but not M57. In addition, one or two mesothoracic DUM neurons send axon collaterals intersegmentally to M59. This is the first demonstration of the innervation of neck muscles by DUM neurons.
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We describe the molecular analysis and cellular expression of the insect peptide neurohormone, bursicon. Bursicon triggers the sclerotization of the soft insect cuticle after ecdysis. Using protein elution analyses from SDS gels, we... more
We describe the molecular analysis and cellular expression of the insect peptide neurohormone, bursicon. Bursicon triggers the sclerotization of the soft insect cuticle after ecdysis. Using protein elution analyses from SDS gels, we determined the molecular weight of bursicon from different insects to be approximately 30 kDa. Four partial peptide sequences of Periplaneta americana bursicon were obtained from purified nerve cord homogenates separated on two-dimensional gels. Antibodies produced against one of the sequences identified the cellular location of bursicon in different insects and showed that bursicon is co-produced with crustacean cardioactive peptide (CCAP) in the same neurons in all insects tested so far. Additionally, using the partial peptide sequences, we successfully searched the Drosophila genome project for the gene encoding bursicon. With Drosophila as a tool, we can now verify the function of the sequence using transgenic flies. Sequence comparisons also allowed us to verify that bursicon is conserved, corroborating the older data from bioassays and immunohistochemical analyses. The sequence of bursicon will enable further analysis of its function, release, and evolution.
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Summary The muscles which move the antennae of locusts and crickets are innervated by motoneurones of the deutocerebral part of the brain. In addition, these muscles receive axon collaterals of two dorsal, unpaired, median (DUM) neurones... more
Summary The muscles which move the antennae of locusts and crickets are innervated by motoneurones of the deutocerebral part of the brain. In addition, these muscles receive axon collaterals of two dorsal, unpaired, median (DUM) neurones which are located in the suboesophageal ganglion. These DUM neurones also send axons towards the retrocerebral glandular complex.
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In the mushroom bodies of the brain of the cricket Gryllus bimaculatus, the distribution of glutamate-like immunoreactivity is shown by using several immunocytochemical staining protocols and confocal and conventional microscopy.... more
In the mushroom bodies of the brain of the cricket Gryllus bimaculatus, the distribution of glutamate-like immunoreactivity is shown by using several immunocytochemical staining protocols and confocal and conventional microscopy. Glutamate-like staining of intrinsic cells of mushroom bodies (Kenyon cells), their axons and projections, is demonstrated for the first time. Two types of Kenyon cells constituting distinct, separated populations within the perikaryal layer and in prominent neuropilar subcompartments exhibit strong (type III cells) or medium (type II cells) glutamate-like immunoreactivity, whereas the small neurons of a central population (type I cells) lack staining above background. Type III Kenyon cells display a strong immunoreactivity similarly found in some giant neurons and in identified antennal motorneurons by using glutamate as an excitatory transmitter, indicating that also distinct populations of the Kenyon cells use glutamate as a putative transmitter. The pattern of glutamate-like immunoreactivity in the mushroom bodies and in other parts of the brain is different from gamma-aminobutyric acid (GABA)-like immunoreactivity (investigated for comparison). GABA-like immunostaining is particularly prominent in the mushroom body calyces where Kenyon cells have their dendritic branchings. Differences in glutamate-like immunostaining in Kenyon cell subpopulations, together with differences in their arborization and axonal projection patterns, indicate a functional diversity of these neurons.
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SUMMARY Anopheles mosquitoes are the sole vectors of malaria. Although adult females are directly responsible for disease transmission and accordingly have been extensively studied, the survival of pre-adult larval stages is vital.... more
SUMMARY Anopheles mosquitoes are the sole vectors of malaria. Although adult females are directly responsible for disease transmission and accordingly have been extensively studied, the survival of pre-adult larval stages is vital. Mosquito larvae utilize a spectrum of chemosensory and other cues to navigate their aquatic habitats to avoid predators and search for food. Here we examine larval olfactory responses, in which the peripheral components are associated with the antennal sensory cone. Larval behavior and sensory cone responses to volatile stimuli in Anopheles coluzzii demonstrate the sensory cone is particularly tuned to alcohols, thiazoles, and heterocyclics, and these responses can be assigned to discrete groups of sensory cone neurons with distinctive profiles. These studies reveal that the anopheline larvae actively sample volatile odors above their aquatic habitats via a highly sophisticated olfactory system that is sensitive to a broad range of compounds with significant behavioral relevance.
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Uca crenulata, the California species of fiddler crab, was exposed to artificial light conditions to separate the influence of the light cycle from that of the tidal input on its rhythmic motor activity. Under both constant light and... more
Uca crenulata, the California species of fiddler crab, was exposed to artificial light conditions to separate the influence of the light cycle from that of the tidal input on its rhythmic motor activity. Under both constant light and light-dark cycles, rhythmic activity was demonstrated in only 50% of the experimental crabs; the activity of the remaining 50% was random. Individuals
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Research Interests: Genetics, Biology, Medicine, Aedes aegypti, Anopheles, and 8 moreAnimals, Gene, Culex, Anopheles gambiae, Culicidae, Exon, Aedes, and Molecular Sequence Data
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A software package is described, which uses an Apple IIe computer with a digitizing board (Digisector 65) for analysing rapid motions of appendages of small insects from video images. Every 20 ms the program simultaneously analyses the... more
A software package is described, which uses an Apple IIe computer with a digitizing board (Digisector 65) for analysing rapid motions of appendages of small insects from video images. Every 20 ms the program simultaneously analyses the position of two moving appendages after a background correction and the externally applied trigger stimulus. The data may be plotted in high-resolution plots with a matrix printer and evaluated with statistical methods.
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In the cricket, Gryllus campestris, a branch of the nervus tegumentarius runs to the distal part of the optic lobe. This branch contains the axons of interommatidial hair receptors. The axon terminations extend forward into the trito- and... more
In the cricket, Gryllus campestris, a branch of the nervus tegumentarius runs to the distal part of the optic lobe. This branch contains the axons of interommatidial hair receptors. The axon terminations extend forward into the trito- and deutocerebrum, and into the subesophageal- and prothoracic ganglia as shown with the cobalt sulfide staining technique. The possible relevance of these connections is discussed.
Research Interests: Biology, Cricket, Medicine, Axon, Anatomy, and 6 moreOrthoptera, Animals, Medical Physiology, Nervous System, Axons, and Gryllus bimaculatus
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Research Interests: Cricket and Habituation
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SummaryInGryllus campestris the visual field of the compound eye (average spatial angle 207°) and the binocular overlap of both compound eyes (46% of the total visual field) were determined with the aid of the deep pseudopupil, in order... more
SummaryInGryllus campestris the visual field of the compound eye (average spatial angle 207°) and the binocular overlap of both compound eyes (46% of the total visual field) were determined with the aid of the deep pseudopupil, in order to have a reference system for the location of the receptive field of medulla neurons.A detailed quantitative analysis of two types of medulla neurons has been carried out with small test light spots given above a certain background illumination.One type of unit gave sustained off-responses. This type had a large receptive field with an off-center in the medio-posterior part of the eye and an incomplete antagonistic surround. The use of disks moved through the receptive field confirmed the antagonistic center-surround organization.The second type of unit was a sustained on-neuron. Several uniform and large receptive fields without a surround and with different locations in the eye were found. Moving targets of either contrast suppressed the firing of this cell type. In this respect, the cell's response resembled that of a certain type of ganglion cells in the vertebrate retina (uniformity detectors).
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Abstract Bursicon is a polypeptide obligatory for the sclerotization of the newly formed insect cuticle after each molt during larval development. Our study reveals for the first time the basic biochemical characteristics of bursicon of... more
Abstract Bursicon is a polypeptide obligatory for the sclerotization of the newly formed insect cuticle after each molt during larval development. Our study reveals for the first time the basic biochemical characteristics of bursicon of the mealworm beetle Tenebrio molitor. Tenebrio molitor larvae (20 kg; approximately 290,000 animals) were used to establish the purification scheme as outlined. The purification scheme includes 4 prepurification steps, one gel filtration step and 3 HPLC steps and results in an approximately 108,000-fold purification. SDS gel electrophoresis of this material reveals two protein bands at about 30 and 45 kDa. Bioactive bursicon was eluted only from the region containing the 30 kDa protein. Two-dimensional SDS-PAGE show only two spots at 30 kDa; bursicon activity was eluted only from the spot at 30 kDa/5.65 pH. The comparison of the apparent molecular weight of bursicon under reducing and non-reducing conditions indicates that it is a single-chain molecule.
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In the crickets Gryllus bimaculatus and Gryllus campestris, the two intrinsic antennal muscles in the scape (first antennal segment) control antennal movements in the horizontal plane. Of the 17 excitatory antennal motoneurons, three... more
In the crickets Gryllus bimaculatus and Gryllus campestris, the two intrinsic antennal muscles in the scape (first antennal segment) control antennal movements in the horizontal plane. Of the 17 excitatory antennal motoneurons, three motoneurons, two fast and one slow, can be stimulated selectively and their effect on muscle contraction, i.e. antennal movement, measured. Simultaneously, either a common inhibitor (CI) neuron
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All arthropods periodically molt to replace their exoskeleton (cuticle). Immediately after shedding the old cuticle, the neurohormone bursicon causes the hardening and darkening of the new cuticle. Here we show that bursicon, to our... more
All arthropods periodically molt to replace their exoskeleton (cuticle). Immediately after shedding the old cuticle, the neurohormone bursicon causes the hardening and darkening of the new cuticle. Here we show that bursicon, to our knowledge the first heterodimeric cystine knot hormone found in insects, consists of two proteins encoded by the genes burs and pburs (partner of burs). The pburs/burs heterodimer from Drosophila melanogaster binds with high affinity and specificity to activate the G protein-coupled receptor DLGR2, leading to the stimulation of cAMP signaling in vitro and tanning in neck-ligated blowflies. Native bursicon from Periplaneta americana is also a heterodimer. In D. melanogaster the levels of pburs, burs, and DLGR2 transcripts are increased before ecdysis, consistent with their role in postecdysial cuticle changes. Immunohistochemical analyses in diverse insect species revealed the colocalization of pburs- and burs-immunoreactivity in some of the neurosecretor...
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Hormones are often responsible for synchronizing somatic physiological changes with changes in behavior. Ecdysis (i.e., the shedding of the exoskeleton) in insects has served as a useful model for elucidating the molecular and cellular... more
Hormones are often responsible for synchronizing somatic physiological changes with changes in behavior. Ecdysis (i.e., the shedding of the exoskeleton) in insects has served as a useful model for elucidating the molecular and cellular mechanisms of this synchronization, and has provided numerous insights into the hormonal coordination of body and behavior. An example in which the mechanisms have remained enigmatic is the neurohormone bursicon, which, after the final molt, coordinates the plasticization and tanning of the initially folded wings with behaviors that drive wing expansion. The somatic effects of the hormone are governed by bursicon that is released into the blood from neurons in the abdominal ganglion (the B(AG)), which die after wing expansion. How bursicon induces the behavioral programs required for wing expansion, however, has remained unknown. Here we show by targeted suppression of excitability that a pair of bursicon-immunoreactive neurons distinct from the B(AG)...