@article {2508, title = {Juvenile hormone is required to couple imaginal disc formation with nutrition in insects.}, journal = {Science }, volume = {312}, year = {2006}, month = {2006 Jun 2}, pages = {1385-8}, abstract = {

In starved larvae of the tobacco hornworm moth Manduca sexta, larval and imaginal tissues stop growing, the former because they lack nutrient-dependent signals but the latter because of suppression by juvenile hormone. Without juvenile hormone, imaginal discs form and grow despite severe starvation. This hormone inhibits the intrinsic signaling needed for disc morphogenesis and does so independently of ecdysteroid action. Starvation and juvenile hormone treatments allowed the separation of intrinsic and nutrient-dependent aspects of disc growth and showed that both aspects must occur during the early phases of disc morphogenesis to ensure normal growth leading to typical-sized adults.

}, keywords = {Animal Nutritional Physiological Phenomena, Animals, Ecdysteroids, Juvenile Hormones, Larva, Manduca, Morphogenesis, Pyridines}, issn = {1095-9203}, doi = {10.1126/science.1123652}, author = {Truman, J W and Hiruma, K and Allee, J P and Macwhinnie, S G B and Champlin, D T and Riddiford, L M} } @article {2452, title = {Neural network partitioning by NO and cGMP.}, journal = {The Journal of Neuroscience: The Official Journal of the Society for Neuroscience}, volume = {21}, year = {2001}, month = {2001 Mar 1}, pages = {1610-8}, abstract = {

The stomatogastric ganglion (STG) of the crab Cancer productus contains approximately 30 neurons arrayed into two different networks (gastric mill and pyloric), each of which produces a distinct motor pattern in vitro. Here we show that the functional division of the STG into these two networks requires intact NO-cGMP signaling. Multiple nitric oxide synthase (NOS)-like proteins are expressed in the stomatogastric nervous system, and NO appears to be released as an orthograde transmitter from descending inputs to the STG. The receptor of NO, a soluble guanylate cyclase (sGC), is expressed in a subset of neurons in both motor networks. When NO diffusion or sGC activation are blocked within the ganglion, the two networks combine into a single conjoint circuit. The gastric mill motor rhythm breaks down, and several gastric neurons pattern switch and begin firing in pyloric time. The functional reorganization of the STG is both rapid and reversible, and the gastric mill motor rhythm is restored when the ganglion is returned to normal saline. Finally, pharmacological manipulations of the NO-cGMP pathway are ineffective when descending modulatory inputs to the STG are blocked. This suggests that the NO-cGMP pathway may interact with other biochemical cascades to partition rhythmic motor output from the ganglion.

}, keywords = {Animals, Arginine, Brachyura, Citrulline, Cyclic GMP, Digestive System, Enzyme Inhibitors, Fluorescent Dyes, Ganglia, Guanylate Cyclase, Immunohistochemistry, Invertebrate, Isoquinolines, Male, Nerve Net, Neurons, Neurotransmitter Agents, Nitric Oxide, Nitric Oxide Donors, Periodicity, Signal Transduction}, issn = {1529-2401}, author = {Scholz, N L and de Vente, J and Truman, J W and Graubard, K} } @article {2451, title = {Tiling of the body wall by multidendritic sensory neurons in Manduca sexta.}, journal = {The Journal of Comparative Neurology}, volume = {440}, year = {2001}, month = {2001 Nov 19}, pages = {271-83}, abstract = {

A plexus of multidendritic sensory neurons, the dendritic arborization (da) neurons, innervates the epidermis of soft-bodied insects. Previous studies have indicated that the plexus may comprise distinct subtypes of da neurons, which utilize diverse cyclic 3{\textquoteright},5{\textquoteright}-guanosine monophosphate signaling pathways and could serve several functions. Here, we identify three distinct classes of da neurons in Manduca, which we term the alpha, beta, and gamma classes. These three classes differ in their sensory responses, branch complexity, peripheral dendritic fields, and axonal projections. The two identified alpha neurons branch over defined regions of the body wall, which in some cases correspond to specific natural folds of the cuticle. These cells project to an intermediate region of the neuropil and appear to function as proprioceptors. Three beta neurons are characterized by long, sinuous dendritic branches and axons that terminate in the ventral neuropil. The function of this group of neurons is unknown. Four neurons belonging to the gamma class have the most complex peripheral dendrites. A representative gamma neuron responds to forceful touch of the cuticle. Although the dendrites of da neurons of different classes may overlap extensively, cells belonging to the same class show minimal dendritic overlap. As a result, the body wall is independently tiled by the beta and gamma da neurons and partially innervated by the alpha neurons. These properties of the da system likely allow insects to discriminate the quality and location of several types of stimuli acting on the cuticle.

}, keywords = {Afferent, Animals, Central Nervous System, Dendrites, Electrophysiology, Epidermis, Manduca, Neurons, Synaptic Transmission}, issn = {0021-9967}, doi = {10.1002/cne.1385}, author = {Grueber, W B and Graubard, K and Truman, J W} } @article {2453, title = {Ecdysteroid coordinates optic lobe neurogenesis via a nitric oxide signaling pathway.}, journal = {Development}, volume = {127}, year = {2000}, month = {2000 Aug 15}, pages = {3543-51}, abstract = {

Proliferation of neural precursors in the optic lobe of Manduca sexta is controlled by circulating steroids and by local production of nitric oxide (NO). Diaphorase staining, anti-NO synthase (NOS) immunocytochemistry and the NO-indicator, DAF-2, show that cells throughout the optic anlage contain NOS and produce NO. Signaling via NO inhibits proliferation in the anlage. When exposed to low levels of ecdysteroid, NO production is stimulated and proliferation ceases. When steroid levels are increased, NO production begins to decrease within 15 minutes independent of RNA or protein synthesis and cells rapidly resume proliferation. Resumption of proliferation is not due simply to the removal of NO repression though, but also requires an ecdysteroid stimulatory pathway. The consequence of these opposing pathways is a sharpening of the responsiveness to the steroid, thereby facilitating a tight coordination between development of the different elements of the adult visual system.

}, keywords = {Animals, Cell Division, Ecdysterone, Enzyme Inhibitors, Manduca, Neurons, NG-Nitroarginine Methyl Ester, Nitric Oxide, Nitric Oxide Synthase, Nitric Oxide Synthase Type I, Nonmammalian, Optic Lobe, Signal Transduction, Stem Cells}, issn = {0950-1991}, author = {Champlin, D T and Truman, J W} } @article {2454, title = {The RXR ortholog USP suppresses early metamorphic processes in Drosophila in the absence of ecdysteroids.}, journal = {Development}, volume = {127}, year = {2000}, month = {2000 Mar 15}, pages = {1151-9}, abstract = {

The steroid hormone 20-hydroxyecdysone (20E) initiates metamorphosis in insects by signaling through the ecdysone receptor complex, a heterodimer of the ecdysone receptor (EcR) and ultraspiracle (USP). Analysis of usp mutant clones in the wing disc of Drosophila shows that in the absence of USP, early hormone responsive genes such as EcR, DHR3 and E75B fail to up-regulate in response to 20E, but other genes that are normally expressed later, such as (\&bgr;)-Ftz-F1 and the Z1 isoform of the Broad-Complex (BRC-Z1), are expressed precociously. Sensory neuron formation and axonal outgrowth, two early metamorphic events, also occur prematurely. In vitro experiments with cultured wing discs showed that BRC-Z1 expression and early metamorphic development are rendered steroid-independent in the usp mutant clones. These results are consistent with a model in which these latter processes are induced by a signal arising during the middle of the last larval stage but suppressed by the unliganded EcR/USP complex. Our observations suggest that silencing by the unliganded EcR/USP receptor and the subsequent release of silencing by moderate steroid levels may play an important role in coordinating early phases of steroid driven development.

}, keywords = {Afferent, Animals, Biological, Developmental, DNA-Binding Proteins, Drosophila, Ecdysteroids, Ecdysterone, Female, Gene Expression Regulation, Gene Targeting, Genes, Insect, Male, Metamorphosis, Models, Neurons, Receptors, Signal Transduction, Steroid, Steroids, Transcription Factors, Up-Regulation, Wing}, issn = {0950-1991}, author = {Schubiger, M and Truman, J W} } @article {2455, title = {The origins of insect metamorphosis.}, journal = {Nature}, volume = {401}, year = {1999}, month = {1999 Sep 30}, pages = {447-52}, abstract = {

Insect metamorphosis is a fascinating and highly successful biological adaptation, but there is much uncertainty as to how it evolved. Ancestral insect species did not undergo metamorphosis and there are still some existing species that lack metamorphosis or undergo only partial metamorphosis. Based on endocrine studies and morphological comparisons of the development of insect species with and without metamorphosis, a novel hypothesis for the evolution of metamorphosis is proposed. Changes in the endocrinology of development are central to this hypothesis. The three stages of the ancestral insect species-pronymph, nymph and adult-are proposed to be equivalent to the larva, pupa and adult stages of insects with complete metamorphosis. This proposal has general implications for insect developmental biology.

}, keywords = {Animals, Biological, Biological Evolution, Insect Hormones, Insects, Juvenile Hormones, Metamorphosis, Nymph, Wing}, issn = {0028-0836}, doi = {10.1038/46737}, author = {Truman, J W and Riddiford, L M} } @article {2456, title = {Drosophila EcR-B ecdysone receptor isoforms are required for larval molting and for neuron remodeling during metamorphosis.}, journal = {Development}, volume = {125}, year = {1998}, month = {1998 Jun}, pages = {2053-62}, abstract = {

During the metamorphic reorganization of the insect central nervous system, the steroid hormone 20-hydroxyecdysone induces a wide spectrum of cellular responses including neuronal proliferation, maturation, cell death and the remodeling of larval neurons into their adult forms. In Drosophila, expression of specific ecdysone receptor (EcR) isoforms has been correlated with particular responses, suggesting that different EcR isoforms may govern distinct steroid-induced responses in these cells. We have used imprecise excision of a P element to create EcR deletion mutants that remove the EcR-B promoter and therefore should lack EcR-B1 and EcR-B2 expression but retain EcR-A expression. Most of these EcR-B mutant animals show defects in larval molting, arresting at the boundaries between the three larval stages, while a smaller percentage of EcR-B mutants survive into the early stages of metamorphosis. Remodeling of larval neurons at metamorphosis begins with the pruning back of larval-specific dendrites and occurs as these cells are expressing high levels of EcR-B1 and little EcR-A. This pruning response is blocked in the EcR-B mutants despite the fact that adult-specific neurons, which normally express only EcR-A, can progress in their development. These observations support the hypothesis that different EcR isoforms control cell-type-specific responses during remodeling of the nervous system at metamorphosis.

}, keywords = {Animals, Biological, Drosophila, Genes, Insect, Insertional, Larva, Lethal, Metamorphosis, Molting, Mutagenesis, Nervous System, Neurons, Receptors, Sequence Deletion, Steroid}, issn = {0950-1991}, author = {Schubiger, M and Wade, A A and Carney, G E and Truman, J W and Bender, M} } @article {2457, title = {Ecdysteroids govern two phases of eye development during metamorphosis of the moth, Manduca sexta.}, journal = {Development}, volume = {125}, year = {1998}, month = {1998 Jun}, pages = {2009-18}, abstract = {

The eye primordium of the moth, Manduca sexta, shows two different developmental responses to ecdysteroids depending on the concentration to which it is exposed. Tonic exposure to moderate levels of 20-hydroxyecdysone (20E) or its precursor, ecdysone, are required for progression of the morphogenetic furrow across the primordium. Proliferation, cell-type specification and organization of immature ommatidial clusters occur in conjunction with furrow progression. These events can be reversibly started or stopped in cultured primordia simply by adjusting levels of ecdysteroid to be above or below a critical threshold concentration. In contrast, high levels of 20E cause maturation of the photoreceptors and the support cells that comprise the ommatidia. Ommatidial maturation normally occurs after the furrow has crossed the primordium, but premature exposure to high levels of 20E at any time causes precocious maturation. In such cases, the furrow arrests irreversibly and cells behind the furrow produce a well-formed, but miniature, eye. Precocious and catastrophic metamorphosis occurs throughout such animals, suggesting that ecdysteroids control development of other tissues in a manner similar to the eye. The threshold concentrations of 20E required for furrow progression versus ommatidial maturation differ by about 17-fold. This capacity to regulate distinct phases of development by different concentrations of a single hormone is probably achieved by differential sensitivity of target gene promoters to induction by the hormone-bound receptor(s).

}, keywords = {Amphibians, Animals, Biological, Ecdysone, Ecdysteroids, Ecdysterone, Eye, Gene Expression Regulation, Genes, Insect, Invertebrate, Larva, Manduca, Metamorphosis, Photoreceptor Cells, Pupa, Species Specificity, Steroids, Time Factors}, issn = {0950-1991}, author = {Champlin, D T and Truman, J W} } @article {2458, title = {Disruption of a behavioral sequence by targeted death of peptidergic neurons in Drosophila.}, journal = {Neuron}, volume = {19}, year = {1997}, month = {1997 Oct}, pages = {813-23}, abstract = {

The neuropeptide eclosion hormone (EH) is a key regulator of insect ecdysis. We tested the role of the two EH-producing neurons in Drosophila by using an EH cell-specific enhancer to activate cell death genes reaper and head involution defective to ablate the EH cells. In the EH cell knockout flies, larval and adult ecdyses were disrupted, yet a third of the knockouts emerged as adults, demonstrating that EH has a significant but nonessential role in ecdysis. The EH cell knockouts had discrete behavioral deficits, including slow, uncoordinated eclosion and an insensitivity to ecdysis-triggering hormone. The knockouts lacked the lights-on eclosion response despite having a normal circadian eclosion rhythm. This study represents a novel approach to the dissection of neuropeptide regulation of a complex behavioral program.

}, keywords = {Animals, Cell Death, Circadian Rhythm, Crosses, Darkness, DNA Transposable Elements, Drosophila, Embryo, Genetic, Green Fluorescent Proteins, Insect Hormones, Invertebrate, Larva, Light, Luminescent Proteins, Mutagenesis, Neurons, Neuropeptides, Nonmammalian, Photoreceptor Cells, Recombinant Fusion Proteins}, issn = {0896-6273}, author = {McNabb, S L and Baker, J D and Agapite, J and Steller, H and Riddiford, L M and Truman, J W} } @article {2459, title = {Neuropeptide hierarchies and the activation of sequential motor behaviors in the hawkmoth, Manduca sexta.}, journal = {The Journal of Neuroscience: The Official Journal of the Society for Neuroscience}, volume = {17}, year = {1997}, month = {1997 Jun 1}, pages = {4389-97}, abstract = {

In insects, the shedding of the old cuticle at the end of a molt involves a stereotyped sequence of distinct behaviors. Our studies on the isolated nervous system of Manduca sexta show that the peptides ecdysis-triggering hormone (ETH) and crustacean cardioactive peptide (CCAP) elicit the first two motor behaviors, the pre-ecdysis and ecdysis behaviors, respectively. Exposing isolated abdominal ganglia to ETH resulted in the generation of sustained pre-ecdysis bursts. By contrast, exposing the entire isolated CNS to ETH resulted in the sequential appearance of pre-ecdysis and ecdysis motor outputs. Previous research has shown that ETH activates neurons within the brain that then release eclosion hormone within the CNS. The latter elevates cGMP levels within and increases the excitability of a group of neurons containing CCAP. In our experiments, the ETH-induced onset of ecdysis bursts was always associated with a rise in intracellular cGMP within these CCAP neurons. We also found that CCAP immunoreactivity decreases centrally during normal ecdysis. Isolated, desheathed abdominal ganglia responded to CCAP by generating rhythmical ecdysis bursts. These ecdysis motor bursts persisted as long as CCAP was present and could be reinduced by successive application of the peptide. CCAP exposure also actively terminated pre-ecdysis bursts from the abdominal CNS, even in the continued presence of ETH. Thus, the sequential performance of the two behaviors arises from one modulator activating the first behavior and also initiating the release of the second modulator. The second modulator then turns off the first behavior while activating the second.

}, keywords = {Animal, Animals, Antibody Specificity, Behavior, Calcitonin, Cyclic GMP, Electrophysiology, Ganglia, Insect Hormones, Invertebrate, Larva, Manduca, Molting, Motor Activity, Nervous System, Nervous System Physiological Phenomena, Neuropeptides, Peptide Fragments, Peptides, Sensitivity and Specificity}, issn = {0270-6474}, author = {Gammie, S C and Truman, J W} } @article {2460, title = {Nitric oxide-sensitive guanylate cyclase activity is associated with the maturational phase of neuronal development in insects.}, journal = {Development}, volume = {122}, year = {1996}, month = {1996 Dec}, pages = {3949-58}, abstract = {

Many developing insect neurones pass through a phase when they respond to nitric oxide (NO) by producing cyclic GMP. Studies on identified grasshopper motoneurones show that this NO sensitivity appears after the growth cone has arrived at its target but before it has started to send out branches. NO sensitivity typically ends as synaptogenesis is nearing completion. Data from interneurones and sensory neurones are also consistent with the hypothesis that NO sensitivity appears as a developing neurone changes from axonal outgrowth to maturation and synaptogenesis. Cyclic GMP likely constitutes part of a retrograde signalling pathway between a neurone and its synaptic partner. NO sensitivity also appears in some mature neurones at times when they may be undergoing synaptic rearrangement. Comparative studies on other insects indicate that the association between an NO-sensitive guanylate cyclase and synaptogenesis is an ancient one, as evidenced by its presence in both ancient and more recently evolved insect groups.

}, keywords = {Afferent, Animals, Cyclic GMP, Dihydrolipoamide Dehydrogenase, Drosophila melanogaster, Grasshoppers, Guanylate Cyclase, Insects, Interneurons, Motor Neurons, Nervous System, Neurons, Nitric Oxide, Nitroprusside, Phylogeny}, issn = {0950-1991}, author = {Truman, J W and de Vente, J and Ball, E E} } @article {2461, title = {Neuropeptide induction of cyclic GMP increases in the insect CNS: resolution at the level of single identifiable neurons.}, journal = {The Journal of Neuroscience: The Official Journal of the Society for Neuroscience}, volume = {14}, year = {1994}, month = {1994 Dec}, pages = {7704-12}, abstract = {

In insects, the neuropeptide eclosion hormone (EH) acts on the CNS to evoke the stereotyped behaviors that cause ecdysis, the shedding of the cuticle at the end of each molt. Concomitantly, EH induces an increase in cyclic GMP (cGMP). Using antibodies against this second messenger, we show that this increase is confined to a network of 50 peptidergic neurons distributed throughout the CNS. Increases appeared 30 min after EH treatment, spread rapidly throughout these neurons, and were extremely long lived. We show that this response is synaptically driven, and does not involve the soluble, nitric oxide (NO)-activated, guanylate cyclase. Stereotyped variations in the duration of the cGMP response among neurons suggest a role in coordinating responses having different latencies and durations.

}, keywords = {Animals, Central Nervous System, Cyclic GMP, Enzyme Activation, Guanylate Cyclase, Immunohistochemistry, Insect Hormones, Manduca, Neurons, Synapses, Time Factors}, issn = {0270-6474}, author = {Ewer, J and de Vente, J and Truman, J W} } @article {2462, title = {The regulation of transmitter expression in postembryonic lineages in the moth Manduca sexta. II. Role of cell lineage and birth order.}, journal = {The Journal of Neuroscience: The Official Journal of the Society for Neuroscience}, volume = {11}, year = {1991}, month = {1991 Jul}, pages = {1990-7}, abstract = {

The expression of GABA is restricted to the progeny of only six of the 24 identified postembryonic lineages in the thoracic ganglia of the tobacco hornworm, Manduca sexta (Witten and Truman, 1991). It is colocalized with a peptide similar to molluscan small cardioactive peptide B (SCPB) in some of the neurons in two of the six lineages. By combining chemical ablation of the neuroblasts at specific larval stages with birth dating of the progeny, we tested whether the expression of GABA and the SCPB-like peptide was determined strictly by cell lineage or involved cellular interactions among the members of individual clonal groups. Chemical ablation of the six specific neuroblasts that produced the GABA-positive neurons (E, K, M, N, T, and X) or of the two that produced the GABA + SCPB-like-immunoreactive neurons (K, M) prior to the generation of their lineages resulted in the loss of these immunoreactivities. These results suggest that regulation between lineages did not occur. Ablation of the K and M neuroblasts after they had produced a small portion of their lineages had no effect on the expression of GABA, but did affect the pattern of the SCPB-like immunoreactivity. Combining birth-dating techniques with transmitter immunocytochemistry revealed that it was the position in the birth order and not interactions among the clonally related neurons that influenced the peptidergic phenotype. These results suggest that cell lineage is involved in establishing the GABAergic phenotype and that both cell lineage and birth order influence the determination of the peptidergic phenotype.(ABSTRACT TRUNCATED AT 250 WORDS)

}, keywords = {Animals, Cell Communication, Cell Differentiation, gamma-Aminobutyric Acid, Ganglia, Immunohistochemistry, Invertebrate Hormones, Larva, Moths, Nervous System, Neurons, Neuropeptides, Neurotransmitter Agents, Phenotype, Pupa}, issn = {0270-6474}, author = {Witten, J L and Truman, J W} } @article {2463, title = {Postmetamorphic cell death in the nervous and muscular systems of Drosophila melanogaster.}, journal = {The Journal of Neuroscience: The Official Journal of the Society for Neuroscience}, volume = {10}, year = {1990}, month = {1990 Feb}, pages = {403-1}, abstract = {

Programmed cell death occurs in the nervous and muscular system of newly emerged adult Drosophila melanogaster. Many of the abdominal muscles that were used for eclosion and wing-spreading behavior degenerate by 12 hr after eclosion. Related neurons in the ventral ganglion also die within the first 24 hr. Ligation experiments showed that the muscle breakdown is triggered by a signal from the anterior region, presumably the head, that occurs about 1 hr before adult emergence. The timing of this signal suggests that eclosion hormone may be involved. Although muscle death is triggered prior to ecdysis, it can be delayed, at least temporarily, by forcing the emerging flies to show a prolonged ecdysis behavior. In contrast to the muscles, the death of the neurons is triggered after emergence. The signal for neuronal degeneration is closely correlated with the initiation of wing inflation behavior. Ligation and digging experiments and behavioral manipulations that either blocked or delayed wing expansion behavior had a parallel effect in suppressing or delaying neuronal death.

}, keywords = {Animal, Animals, Behavior, Biological, Cell Survival, Drosophila melanogaster, Female, Ligation, Male, Metamorphosis, Muscles, Nervous System, Neurons}, issn = {0270-6474}, author = {Kimura, K I and Truman, J W} } @article {2464, title = {Postembryonic neurogenesis in the CNS of the tobacco hornworm, Manduca sexta. I. Neuroblast arrays and the fate of their progeny during metamorphosis.}, journal = {The Journal of Comparative Neurology}, volume = {255}, year = {1987}, month = {1987 Jan 22}, pages = {548-59}, abstract = {

The tobacco hornworm Manduca sexta exhibits dramatic changes in its body morphology and behavior as it is transformed from a larva into an adult during metamorphosis. Accompanying these changes is an extensive reorganization of this moth{\textquoteright}s central nervous system (CNS), which involves both the death and remodeling of subsets of larval neurons. We report here that the segmental ganglia of the larvae also contain a stereotyped array of identifiable neuronal stem cells (neuroblasts) that contribute over 2,000 cells to each thoracic ganglion and about 40-80 cells to each abdominal ganglion. The distribution of these neuroblasts varies in a segment specific manner. Dormant neuroblasts are found adjacent to the neuropil in late embryos and early first instar larvae. After the molt to the second instar, these cells enlarge and begin to divide. Through a series of asymmetrical divisions, each neuroblast generates a discrete nest of 10-90 progeny by the end of larval life. These progeny (the imaginal nest cells) are developmentally arrested at an early stage of differentiation and remain so until metamorphosis. At the onset of metamorphosis, a wave of cell death sweeps through the nests, the extent of the death being much greater within the abdominal nests than in the thoracic nests. The surviving imaginal nest cells then differentiate to become functional neurons that are incorporated into the adult CNS.

}, keywords = {Animals, Biological, Cell Division, Central Nervous System, Larva, Lepidoptera, Metamorphosis, Moths, Neurons}, issn = {0021-9967}, doi = {10.1002/cne.902550407}, author = {Booker, R and Truman, J W} } @article {2465, title = {Endocrine regulation of the form and function of axonal arbors during insect metamorphosis.}, journal = {The Journal of Neuroscienc : The Official Journal of the Society for Neuroscience}, volume = {6}, year = {1986}, month = {1986 Jan}, pages = {293-9}, abstract = {

By discrete manipulation of the endocrine cues that control insect metamorphosis, it has been possible to examine the mechanisms governing the growth of neural processes during development. During the transition from larva to pupa in the hawkmoth, Manduca sexta, identified sensory neurons reorganize their central projections to evoke a new behavior{\textendash}the gintrap reflex. Topical application of a juvenile hormone analog to the peripheral cell bodies of these sensory neurons during a critical period of development caused them to retain their larval commitment rather than undergo pupal development with the rest of the animal. The sensory neurons retained the larval arborization pattern within the pupal CNS and were unable to evoke the gin-trap reflex. Thus, the hormonal environment of the cell body is critical for controlling growth and synapse formation by distant axonal processes.

}, keywords = {Animal, Animals, Axons, Behavior, Biological, Cobalt, Juvenile Hormones, Larva, Lepidoptera, Metamorphosis, Moths, Neurons}, issn = {0270-6474}, author = {Levine, R B and Truman, J W and Linn, D and Bate, C M} } @article {2466, title = {Dendritic reorganization of an identified motoneuron during metamorphosis of the tobacco hornworm moth.}, journal = {Science}, volume = {192}, year = {1976}, month = {1976 Apr 30}, pages = {477-9}, abstract = {

In the tobacco hornworm, many larval motoneurons become respecified and supply new muscles in the adult. Changes in the morphology of one such neuron were examined through metamorphosis. The dendritic pattern of the adult comes about both by outgrowth from the primary and secondary branches of the larval neuron and by the development of new branches that are unique to the adult.

}, keywords = {Age Factors, Animals, Biological, Cell Differentiation, Dendrites, Larva, Lepidoptera, Male, Metamorphosis, Moths, Motor Neurons, Pupa}, issn = {0036-8075}, author = {Truman, J W and Reiss, S E} } @article {2467, title = {Neuroendocrine control of ecdysis in silkmoths.}, journal = {Science}, volume = {167}, year = {1970}, month = {1970 Mar 20}, pages = {1624-6}, abstract = {

An adult moth sheds its pupal skin only during a specific period of the day. The brain is necessary for the synchronization of this behavior with the environmental photoperiod. This function is fully preserved when all the brain{\textquoteright}s nervous connections are severed or when a "loose" brain is transplanted into the tip of the abdomen. By appropriate experiments it was possible to show that the entire mechanism is brain-centered. The components include a photoreceptor mechanism, a clock, and a neuroendocrine output. The clock-controlled release of the hormone acts on the central nervous system to trigger a species-specific behavior pattern which culminates in ecdysis.

}, issn = {0036-8075}, doi = {10.1126/science.167.3925.1624}, author = {Truman, J W and Riddiford, L M} }