Article

Identification of Ecdysis-Triggering Hormone from an Epitracheal Endocrine System

Department of Entomology, University of California, Riverside 92521, USA.
Science (Impact Factor: 33.61). 02/1996; 271(5245):88-91. DOI: 10.1126/science.271.5245.88
Source: PubMed

ABSTRACT

Developing insects repeatedly shed their cuticle by means of a stereotyped behavior called ecdysis, thought to be initiated
by the brain peptide eclosion hormone. Here an ecdysis-triggering hormone, Mas-ETH, is described from the tobacco hornworm
Manduca sexta. Mas-ETH contains 26 amino acids and is produced by a segmentally distributed endocrine system of epitracheal glands (EGs).
The EGs undergo a marked reduction in volume, appearance, and immunohistochemical staining during ecdysis, at which time Mas-ETH
is found in the hemolymph. Injection of EGs extract or synthetic Mas-ETH into pharate larvae, pupae, or adults initiates preecdysis
within 2 to 10 minutes, followed by ecdysis. Sensitivity to injected Mas-ETH appears much earlier before ecdysis and occurs
with shorter latency than that reported for eclosion hormone. The isolated central nervous system responds to Mas-ETH, but
not to eclosion hormone, with patterned motor bursting corresponding to in vivo preecdysis and ecdysis. Mas-ETH may be an
immediate blood-borne trigger for ecdysis through a direct action on the nervous system.

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    • "In this study, analysis of the test insect fed with C. microphylla extracts, revealed a developmental disruption in which the insects died (between 10 and 25 ppm) during pharate conditions after initiation of molting (the apolysis step), without completion of morphogenesis . During a molt, ecdysteroid levels first rise to stimulate onset of apolysis and cuticle synthesis, but then must fall to facilitate the release of eclosion hormone (EH) (Truman et al., 1983; 2002) and the ecdysis-triggering hormone (ETH) (Zitnan et al., 1996, 1999). These last substances act in concert to trigger insect ecdysis during the final stages of the molt. "
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    ABSTRACT: Extracts obtained from a common shrub that occurs as part of vegetative species growing on arid lands of North-Central Chile and adjacent central Argentina known as “piquilin” Condalia microphylla (Rhamnaceae) showed insect growth inhibitory activity against the fall armyworm Spodoptera frugiperda, yellow meal worm Tenebrio molitor and fruit fly Drosophila melanogaster larvae in artificial diet feeding assays. The effects of these extracts on mortality, antifeedancy and growth inhibition were examined. The phytochemical profile of the most active extract was examined with conventional chromatographic and spectroscopic procedures. This n-hexane extract showed a high percentage of hentriacontane and triacontane. The observed mortality strongly correlates with the contents of these long-chain n-alkanes compounds, the LD50 for n-hexane, ethyl acetate and methanol extracts against S. frugiperda, were 3.89, 9.4, and 9.7 ppm; against T. molitor 5.2, 14.2, and 20.4 ppm, and against D. melanogaster 3.23, 7.65 and 17.9 ppm, respectively. © 2012 Elsevier B.V. All rights reserved.
    Full-text · Article · Mar 2013 · Industrial Crops and Products
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    • "peptide modulation of behavior. In the moth Manduca, ETH (and the cosynthesized P-ETH peptide) derives from endocrine cells associated with trachea and elicits coordinated behavior by directly activating diverse neural targets (Zitnan et al., 1996). To discover the cellular basis for this precise modulatory mechanisms, Kim et al. (2006a) identified the receptors specifically tuned to ETH—these GPCRs are most closely related to receptors for mammalian neuromedins and TRH (Hewes and Taghert, 2001; Park et al., 2003). "
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    ABSTRACT: Neuropeptides modulate neural circuits controlling adaptive animal behaviors and physiological processes, such as feeding/metabolism, reproductive behaviors, circadian rhythms, central pattern generation, and sensorimotor integration. Invertebrate model systems have enabled detailed experimental analysis using combined genetic, behavioral, and physiological approaches. Here we review selected examples of neuropeptide modulation in crustaceans, mollusks, insects, and nematodes, with a particular emphasis on the genetic model organisms Drosophila melanogaster and Caenorhabditis elegans, where remarkable progress has been made. On the basis of this survey, we provide several integrating conceptual principles for understanding how neuropeptides modulate circuit function, and also propose that continued progress in this area requires increased emphasis on the development of richer, more sophisticated behavioral paradigms.
    Preview · Article · Oct 2012 · Neuron
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    • "Using Eclosion Hormone (EH) and, more recently, ETH to initiate ecdysis has been a standard technique for many years (eg.Weeks and Truman 1984;Ewer et al. 1997;Zitnan et al. 1996; Fig. 5). In particular, the ease of synthesizing ETH, compared to purification of EH from homogenized glands, has made it an extremely powerful tool for providing better control over the start time of the motor program. "
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    ABSTRACT: We have developed a machine vision–based method for automatically tracking deformations in the body wall to monitor ecdysis behaviors in the hornworm, Manduca sexta. The method utilizes naturally occurring features on the animal’s body (spiracles) and is highly accurate (>95 % success in tracking). Moreover, it is robust to unanticipated changes in the animal’s position and in lighting, and in the event tracking of specific features is lost, tracking can be reestablished within a few cycles without input from the user. We have paired our tracking technique with electromyography and have also compared our in vivo results to fictive motor patterns recorded from isolated nerve cords. We found no major difference in the cycle periods of contractions during naturally occurring ecdysis compared to ecdysis initiated prematurely through injection of the peptide ecdysis-triggering hormone, and we confirmed that the ecdysis period in vivo is statistically similar to that of the fictive motor pattern.
    Full-text · Article · Sep 2012 · Invertebrate Neuroscience
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