David Schooley


Photo of David Schooley

Emeritus Professor

Department of Biochemistry and Molecular Biology
University of Nevada/Mail Stop 330
1664 North Virginia Street
Reno,  Nevada   89557

Office: (775) 784-4136
Lab: 784-4126

Email: schooley@unr.edu
Building: Howard Medical Science,  Office 160

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EDUCATION
B.Sc. Chemistry, 1963 New Mexico Highland University
Ph.D. Organic Chemistry, 1968 Stanford University

ACADEMIC & RESEARCH INTEREST

Insect growth and development differs from that of mammals, and the hormones controlling this development have no counterpart in vertebrates. Ecdysone is a steroid which causes the shedding of the exoskeleton necessary for the insect to molt. Juvenile hormone modulates the action of ecdysone, controlling whether a larva molts to a larva or to a pupa. Juvenile hormone must be absent for a pupa to molt to an adult: this forms the basis of the insecticide methoprene, a synthetic molecule with juvenile hormone activity. I was involved in the development of this product before moving to UNR.

My group identified four of the six known insect juvenile hormones and a related juvenile hormone from crabs. We have studied how insects create these sesquiterpenoids, four of which are biosynthetically unique with ethyl side branches replacing the usual methyl group. We found that the "extra" carbon atoms in these molecules comes from propionate, which is converted to homologs of normal terpene precursors. The glands producing these hormones vigorously metabolize the amino acids valine and/or isoleucine to a coenzyme A ester of propionate. We showed that the ability of the insect to produce the ethyl branched juvenile hormones is related to its ability to metabolize isoleucine or valine.

I have also done a great deal of research on the identification and biochemistry of insect peptide hormones which control a variety of processes. We identified from cockroach brains two peptides which raise its blood sugar levels, and later identified from Manduca sexta the hormones which stimulate (allatotropin) and stop (allatostatin) juvenile hormone production by the corpora allata, as well as the eclosion hormone, a 62 amino acid peptide which initiates the behavior necessary for an insect to escape from the old exoskeleton after it molts. We also identified a diuretic hormone from Manduca which stimulates ion secretion leading to urine production. This peptide is related to a vertebrate peptide known as CRF. We have done extensive research on this family of peptides, showing how Manduca DH is metabolized, identified seven more of these CRF-like DH from five other species of insects, and are currently trying to determine the intracellular mechanisms by which these peptides stimulate the vacuolar ATPase which powers cation secretion. From a cockroach we identified the first member of another family of diuretic hormones related to calcitonin, a controller of calcium balance in mammals. Using genomic data, we have synthesized diuretic hormones from Drosophila melanogaster and Anopheles gambiae (the malaria mosquito) and studied their physiological effects with Geoff Coast from Birkbeck College. We showed that the Anopheles calcitonin-like DH is the specific form which causes the massive excretion of sodium required when the adult female mosquito takes a blood meal. We are also interested in studying the differences in action of these two different families of peptides, both of which elevate intracellular cyclic AMP but with different outcomes in different species.

COURSES & TEACHING RESPONSIBILITIES

BCH 417/617, Metabolic Regulation

AWARDS, HONORS, & PROFESSIONAL RECOGNITION

1990- Baxter, Burdick, and Jackson International Award; Agrochemical Division, American Chemical Society

1993- Nevada Agricultural Foundation Arvin Boerlin Research Award

1993- University of Nevada Foundation Professor

2003- UNR College of Ag., Biotech., and Natural Resources Teacher of the Year

2004- UNR Outstanding Researcher Award

2004- University of Nevada Regents Researcher Award

2006- Ted Hopkins Insect Physiologist Award, Kansas State University

2007- Kenneth A. Spencer Award, Kansas City American Chemical Society Section

REPRESENTATIVE PUBLICATIONS

Journals
Christie, A. E., Jensen, D. A., Schegg, K. M., Schooley, D. A., Dickinson, P. S. 2013, Identification of a calcitonin-like diuretic hormone that functions as an intrinsic modulator of the American lobster, Homarus americanus, cardiac neuromuscular system., J. Experimental Biology, 213, 118-127.
Christie AE, Stevens JS, Bowers MR, Chapline MC, Jensen DA, Schegg KM, Goldwaser J, Kwiatkowski MA, Pleasant TK Jr, Shoenfeld L, Tempest LK, Williams CR, Wiwatpanit T, Smith CM, Beale KM, Towle DW, Schooley DA, Dickinson PS. 2012, Identification of a calcitonin-like diuretic hormone that functions as an intrinsic modulator of the American lobster, Homarus americanus, cardiac neuromuscular system., J Exp Biol. 2010 Jan 1;213(1):118-27. doi: 10.1242/jeb.037077.
Victoria Te Brugge, Jean-Paul Paluzzi, David A. Schooley and Ian Orchard 2011, Identification of the elusive peptidergic diuretic hormone in the blood-feeding bug Rhodnius prolixus: a CRF-related peptide, J. Exp. Biol., 214, 371-381
Abstract:

Probing of a host and ingestion of a blood-meal in a fifth instar Rhodnius prolixus results in a cascade of tightly integrated events. The huge blood-meal is pumped into the anterior midgut during feeding, then modified by diuresis and stored until it is digested. While serotonin is known to be a diuretic hormone in R. prolixus, a peptidergic factor(s) was also known to play a role in diuresis. In the present study we employed molecular techniques and mass spectrometry to determine the sequence of a native CRF-like peptide from R. prolixus (Rhopr DH). In addition, we confirmed the distribution and localization of Rhopr DH using in situ hybridization and immunohistochemistry, and demonstrated its potent biological activity on both the anterior midgut and Malpighian tubules.

Geoffrey M. Coast and David A. Schooley 2011, Toward a consensus nomenclature for insect neuropeptides and peptide hormones, Peptides/Elsevier, 32, 620-631
Abstract:

The nomenclature currently in use for insect neuropeptide and peptide hormone families is reviewed and suggestions are made as to how it can be rationalized. Based upon this review, a number of conventions are advanced as a guide to a more rationale nomenclature. The scheme that is put forward builds upon the binomial nomenclature scheme proposed by Raina and Gäde in 1988, when just over 20 insect neuropeptides had been identified. Known neuropeptides and peptide hormones are assigned to 32 structurally distinct families, frequently with overlapping functions. The names given to these families are those that are currently in use, and describe a biological function, homology to known invertebrate/vertebrate peptides, or a conserved structural motif. Interspecific isoforms are identified using a five-letter code to indicate genus and species names, and intraspecific isoforms are identified by Roman or Arabic numerals, with the latter used to signify the order in which sequences are encoded on a prepropeptide. The proposed scheme is sufficiently flexible to allow the incorporation of novel peptides, and could be extended to other arthropods and non-arthropod invertebrates.

Christie, A. E., Jensen, D. A., Schegg, K. M., Schooley, D. A., Dickinson, P. S., 2010, Identification of a calcitonin-like diuretic hormone that functions as an intrinsic modulator of the American lobster, Homarus americanus, cardiac neuromuscular system., Journal of Experimental Biology, 213, 118-127.
Hull, J. J., Copley, K. S., Schegg, K. M., Quilici, D. R., Schooley, D. A., Welch, W. H. 2009, De Novo molecular modeling and biophysical characterization of Manduca sexta eclosion hormone., Biochemistry, 48(38), 9047-9060.
Book or Chapter(s) in Books
Schooley, D.A.; Horodyski, F.M. and Coast, Geoffrey M. 2011, Hormones controlling homeostasis in insects, Gilbert, L. (ed.) Insect Endocrinology. Elsevier, pp. 366-429. ISBN 9780123847492
Abstract:

The publication of the extensive seven-volume work Comprehensive Molecular Insect Science provided a complete reference encompassing important developments and achievements in modern insect science. One of the most swiftly moving areas in entomological and comparative research is endocrinology, and this volume, Insect Endocrinology, is designed for those who desire a comprehensive yet concise work on important aspects of this topic. Because this area has moved quickly since the original publication, articles in this new volume are revised, highlighting developments in the related area since its original publication. Insect Endocrinology covers the mechanism of action of insect hormones during growth and metamorphosis as well as the role of insect hormones in reproduction, diapause and the regulation of metabolism. Contents include articles on the juvenile hormones, circadian organization of the endocrine system, ecdysteroid chemistry and biochemistry, as well as new chapters on insulin-like peptides and the peptide hormone Bursicon. This volume will be of great value to senior investigators, graduate students, post-doctoral fellows and advanced undergraduate research students. It can also be used as a reference for graduate courses and seminars on the topic. Chapters will also be valuable to the applied biologist or entomologist, providing the requisite understanding necessary for probing the more applied research areas.