Molecular characterization and cell-specific expression of an ion transport peptide in the tobacco hornworm, <Emphasis Type="Italic">Manduca sexta</Emphasis> |
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| Authors: | Anna L Drexler Christina C Harris Myra G dela Pena Marilyn Asuncion-Uchi Sook Chung Simon Webster Megumi Fuse |
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| Institution: | (1) Department of Biology, San Francisco State University, San Francisco, CA 94132, USA;(2) Department of Biology, University of Washington, Box 351800, Seattle, WA 98195, USA;(3) Department of Cell and Molecular Biology, Tulane University, 2000 Percival Stern Hall, New Orleans, LA 70118, USA;(4) Department of Public Health Sciences, University of California at Davis, One Shields Avenue, TB-168, Davis, CA 95616, USA;(5) Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202, USA;(6) School of Biological Sciences, University of Wales, Bangor, LL57 2UW, Gwynedd, Wales, UK |
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| Abstract: | The crustacean hyperglycemic hormone (CHH) peptides regulate diverse physiological processes from reproduction to metabolism
and molting in arthropods. In insects, the ion transport peptides (ITP), also members of the CHH family, have only been implicated
in ion transport. In this study, we sequenced a nucleotide fragment spanning the conserved A1/A2 region of the putative CHH/ITP
gene. This fragment was amplified from larval cDNA of the tobacco hornworm, Manduca sexta and showed a high degree of sequence conservation with the same region from other insects and, to a lesser degree, with that
of crustacean species, suggesting the presence of a Manduca-specific CHH/ITP mRNA (MasITP mRNA). CHH-like immunocytochemical analyses with two crustacean antisera (from Carcinus maenas and Cancer pagurus) identified the presence of CHH-like immunoreactivity in nervous tissue of all developmental stages, but not in the gut of
M. sexta. Specifically, CHH-like peptides localized to paired type IA2 neurosecretory cells of the pars lateralis of the brain (projecting ipsilaterallly to the corpora cardiaca-allata complex)
and to neurosecretory cells and transverse nerves of the ventral nerve cord in larvae, pupae, and adults. The distribution
of the putative MasITP peptide shifted during development in a manner consistent with metamorphic reorganization. A comparison of hemolymph equivalents
of CHH detected by enzyme-linked immunosorbent assay with CHH-like immunoreactivity in transverse nerves provided evidence
for the release of MasITP from the transverse nerves into the hemolymph at insect ecdysis. These data suggest the presence of an insect ITP in M. sexta and a role for this hormone during ecdysis.
This research was funded by the National Institutes of Health (MBRS SCORE Program-NIGMS) to M.F. (grant no. 2S06 GM52588-09),
by the National Center on Minority Health and Health Disparities (grant no. 5P20-MD000262), an NIH RISE graduate fellowship
to A.L.D. (5 R25 GM59298), an NIH PREP fellowship to C.C.H. and M.A.U. (5 R25 GM64078), an NSF CSU LS-AMP fellowship to C.C.H.
(HRD-9802113), and by NIH MBRS-MARC to M.D.P. (T34 GM08574) and NIH MA/MS-PhD Bridge Scholarship to A.L.D. and C.C.H. (5R25
GM48972). |
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| Keywords: | Ecdysis Crustacean hyperglycemic hormone (CHH) Ion transport peptide (ITP) Transverse nerves Tobacco hornworm Manduca sexta (Insecta) |
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