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Roegner ME, Watson RD. De novo transcriptome assembly and functional annotation for Y-organs of the blue crab (Callinectes sapidus), and analysis of differentially expressed genes during pre-molt. Gen Comp Endocrinol 2020; 298:113567. [PMID: 32710897 DOI: 10.1016/j.ygcen.2020.113567] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 07/14/2020] [Accepted: 07/19/2020] [Indexed: 12/11/2022]
Abstract
Blue crabs (Callinectes sapidus) undergo incremental growth involving the shedding (molting) of the old exoskeleton, and subsequent expansion and re-calcification of the newly synthesized one. The cellular events that lead to molting are triggered by steroid hormones termed ecdysteroids released from Y-organs, paired endocrine glands located in the anterior cephalothorax. The regulatory pathways leading to increased synthesis and release of ecdysteroids are not fully understood, and no transcriptome has yet been published for blue crab Y-organs. Here we report de novo transcriptome assembly and annotation for adult blue crab Y-organs, and differential gene expression (DGE) analysis between Y-organs of intermolt and premolt crabs. After trimming and quality assessment, a total of 91,819,458 reads from four cDNA libraries were assembled using Trinity to form the reference transcriptome. Trinity produced a total of 171,530 contigs coding for 150,388 predicted genes with an average contig length of 613 and an N50 of 940. Of these, TransDecoder predicted 31,661 open reading frames (ORFs), and 10,210 produced non-redundant blastx results through Trinotate annotation. Genes involved in multiple cell signaling pathways, including Ca2+ signaling, cGMP signaling, cAMP signaling, and mTOR signaling were present in the annotated reference transcriptome. DGE analysis showed in premolt Y-organs up-regulated genes involved in energy production, cholesterol metabolism, and exocytosis. The results provide insights into the transcriptome of blue crab Y-organs during a natural (rather than experimentally induced) molting cycle, and constitute a step forward in understanding the cellular mechanisms that underlie stage-specific changes in the synthesis and secretion of ecdysteroids by Y-organs.
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Affiliation(s)
- Megan E Roegner
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - R Douglas Watson
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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2
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McKinney DA, Eum JH, Dhara A, Strand MR, Brown MR. Calcium influx enhances neuropeptide activation of ecdysteroid hormone production by mosquito ovaries. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 70:160-169. [PMID: 26772671 PMCID: PMC4767660 DOI: 10.1016/j.ibmb.2016.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/23/2015] [Accepted: 01/03/2016] [Indexed: 06/05/2023]
Abstract
A critical step in mosquito reproduction is the ingestion of a blood meal from a vertebrate host. In mosquitoes like Aedes aegypti, blood feeding stimulates the release of ovary ecdysteroidogenic hormone (OEH) and insulin-like peptide 3 (ILP3). This induces the ovaries to produce ecdysteroid hormone (ECD), which then drives egg maturation. In many immature insects, prothoracicotropic hormone (PTTH) stimulates the prothoracic glands to produce ECD that directs molting and metamorphosis. The receptors for OEH, ILP3 and PTTH are different receptor tyrosine kinases with OEH and ILP3 signaling converging downstream in the insulin pathway and PTTH activating the mitogen-activated protein kinase pathway. Calcium (Ca(2+)) flux and cAMP have also been implicated in PTTH signaling, but the role of Ca(2+) in OEH, ILP3, and cAMP signaling in ovaries is unknown. Here, we assessed whether Ca(2+) flux affects OEH, ILP3, and cAMP activity in A. aegypti ovaries and also asked whether PTTH stimulated ovaries to produce ECD. Results indicated that Ca(2+) flux enhanced but was not essential for OEH or ILP3 activity, whereas cAMP signaling was dependent on Ca(2+) flux. Recombinant PTTH from Bombyx mori fully activated ECD production by B. mori PTGs, but exhibited no activity toward A. aegypti ovaries. Recombinant PTTH from A. aegypti also failed to stimulate either B. mori PTGs or A. aegypti ovaries to produce ECD. We discuss the implications of these results in the context of mosquito reproduction and ECD biosynthesis by insects generally.
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Affiliation(s)
- David A McKinney
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | - Jai-Hoon Eum
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | - Animesh Dhara
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | - Michael R Strand
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| | - Mark R Brown
- Department of Entomology, University of Georgia, Athens, GA 30602, USA.
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Reassessing ecdysteroidogenic cells from the cell membrane receptors' perspective. Sci Rep 2016; 6:20229. [PMID: 26847502 PMCID: PMC4742824 DOI: 10.1038/srep20229] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/23/2015] [Indexed: 02/06/2023] Open
Abstract
Ecdysteroids secreted by the prothoracic gland (PG) cells of insects control the
developmental timing of their immature life stages. These cells have been
historically considered as carrying out a single function in insects, namely the
biochemical conversion of cholesterol to ecdysteroids and their secretion. A growing
body of evidence shows that PG cells receive multiple cues during insect development
so we tested the hypothesis that they carry out more than just one function in
insects. We characterised the molecular nature and developmental profiles of cell
membrane receptors in PG cells of Bombyx mori during the final larval stage
and determined what receptors decode nutritional, developmental and physiological
signals. Through iterative approaches we identified a complex repertoire of cell
membrane receptors that are expressed in intricate patterns and activate previously
unidentified signal transduction cascades in PG cells. The expression patterns of
some of these receptors explain precisely the mechanisms that are known to control
ecdysteroidogenesis. However, the presence of receptors for the notch, hedgehog and
wingless signalling pathways and the expression of innate immunity-related receptors
such as phagocytosis receptors, receptors for microbial ligands and Toll-like
receptors call for a re-evaluation of the role these cells play in insects.
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DeLalio LJ, Dion SM, Bootes AM, Smith WA. Direct effects of hypoxia and nitric oxide on ecdysone secretion by insect prothoracic glands. JOURNAL OF INSECT PHYSIOLOGY 2015; 76:56-66. [PMID: 25747870 DOI: 10.1016/j.jinsphys.2015.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 02/19/2015] [Accepted: 02/22/2015] [Indexed: 06/04/2023]
Abstract
Insect molting and metamorphosis are controlled by the molt stimulating hormone ecdysone. A recent study suggests that reduced tissue oxygenation correlates with the size-sensing mechanism responsible for triggering molting. When reared in hypoxia, larvae of Manduca sexta and Drosophila melanogaster initiate molting at lower weights than do larvae reared in normoxia. Furthermore, in Drosophila, the signaling gas nitric oxide (NO) appears to be required for normal developmental timing. As observed in Drosophila, NO signaling targets the nuclear hormone receptor beta fushi tarazu transcription factor 1 (βFTZ-F1) through activation of Drosophila hormone receptor 3 (DHR3), two key regulators of ecdysone production and metamorphic tissue progression. We set out to directly examine the effects of hypoxia and NO on ecdysone secretion using prothoracic glands from feeding fifth (last) larval stage M. sexta. Our results indicate that in vitro treatment of prothoracic glands with hypoxia (2% oxygen) or the NO donor DETA-NONOate significantly inhibit ecdysone secretion. Protein markers of glandular activity were also in keeping with an initial inhibition, measured a decrease in phosphorylated ERK (extracellular signal regulated kinase) and an increase in non-phosphorylated 4EBP (eukaryotic initiation factor 4E binding protein). Additionally, gene expression levels of Manduca hormone receptor 3 (mhr3), βftz-f1, nitric oxide synthase (nos), and the PTTH receptor torso, were quantified using real-time PCR. NO treatment increased mhr3 expression and decreased nos expression. Hypoxia increased mhr3 transcription after 2 hr, but decreased transcription after 12 hr, with no effect on nos expression. Both NO and hypoxia had small effects on βftz-f1 expression, yet strongly increased torso transcription. Our results demonstrate that, in isolated prothoracic glands, hypoxia and NO signaling directly inhibit ecdysteroid secretion, but at the same time alter aspects of prothoracic gland function that may enhance secretory response.
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Affiliation(s)
- Leon J DeLalio
- Department of Biology, Northeastern University, 134 Mugar Hall, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Sara M Dion
- Department of Biology, Northeastern University, 134 Mugar Hall, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Abigail M Bootes
- Department of Biology, Northeastern University, 134 Mugar Hall, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Wendy A Smith
- Department of Biology, Northeastern University, 134 Mugar Hall, 360 Huntington Avenue, Boston, MA 02115, USA.
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5
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Kim J, Hepat R, Lee D, Kim Y. Protein tyrosine phosphatase encoded in Cotesia plutellae bracovirus suppresses a larva-to-pupa metamorphosis of the diamondback moth, Plutella xylostella. Comp Biochem Physiol A Mol Integr Physiol 2013; 166:60-9. [PMID: 23651929 DOI: 10.1016/j.cbpa.2013.04.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 04/29/2013] [Accepted: 04/29/2013] [Indexed: 01/31/2023]
Abstract
Parasitization by an endoparasitoid wasp, Cotesia plutellae, inhibits a larva-to-pupa metamorphosis of the diamondback moth, Plutella xylostella. This study tested an inhibitory effect of C. plutellae bracovirus (CpBV) on the metamorphosis of P. xylostella. Parasitized P. xylostella exhibited significantly reduced prothoracic gland (PTG) development at the last instar compared to nonparasitized larvae. Expression of the ecdysone receptor (EcR) was markedly suppressed during the last instar larvae parasitized by C. plutellae. By contrast, expression of the insulin receptor (InR) significantly increased in the parasitized larvae. Microinjection of CpBV significantly inhibited the larva-to-pupa metamorphosis of nonparasitized larvae in a dose-dependent manner. Injection of CpBV also inhibited the expression of the EcR and increased the expression of the InR. Individual CpBV segments were transiently expressed in its encoded genes in nonparasitized larvae and screened to determine antimetamorphic viral gene(s). Out of 21 CpBV segments, two viral segments (CpBV-S22 and CpBV-S27) were proved to inhibit larva-to-pupa metamorphosis by transient expression assay. RNA interference of each gene encoded in the viral segments was applied to determine antimetamorphic gene(s). Protein tyrosine phosphatase, early expressed gene, and four hypothetical genes were selected to be associated with the antimetamorphic activity of CpBV. These results suggest that antimetamorphosis of P. xylostella parasitized by C. plutellae is induced by inhibiting PTG development and subsequent ecdysteroid signaling with viral factors of CpBV.
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Affiliation(s)
- Jiwan Kim
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Korea
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6
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Walsh AL, Smith WA. Nutritional sensitivity of fifth instar prothoracic glands in the tobacco hornworm, Manduca sexta. JOURNAL OF INSECT PHYSIOLOGY 2011; 57:809-818. [PMID: 21420972 DOI: 10.1016/j.jinsphys.2011.03.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 03/13/2011] [Accepted: 03/14/2011] [Indexed: 05/30/2023]
Abstract
Insulin-regulated growth of the prothoracic glands appears to play a critical role in timing the last larval molt, and hence metamorphosis. The present study examined insulin signaling in relation to the growth and secretory activity of prothoracic glands in the tobacco hornworm, Manduca sexta. As larvae feed during the first half of the final larval stage, the prothoracic glands grow and ecdysone secretory capacity increases. During this period of growth, we verified the presence of insulin receptor transcript in the prothoracic glands and demonstrated that the glands were responsive to insulin, as evidenced by the in vitro phosphorylation of signaling proteins in the insulin pathway such as Akt/protein kinase B and FOXO. It was predicted that starvation would reduce ecdysone secretion with concomitant changes in insulin signaling. To test this prediction, larvae were starved and changes were quantified in two nutritionally sensitive transcripts, insulin receptor and the translation inhibitor 4EBP. In glands from starved larvae, growth and ecdysone secretory capacity were reduced, and insulin receptor and 4EBP transcripts were increased. The latter changes would be expected to accompany starvation in conjunction with enhanced insulin sensitivity and reduced protein synthesis. Increased transcription of insulin receptor and 4EBP strongly suggest that nutritional deprivation reduces the secretion of endogenous insulin-like hormones. When injected with insulin, 4EBP levels in the prothoracic glands of starved larvae decreased. Thus, insulin appeared to correct starvation-induced deficits in glandular protein synthesis. However, insulin injection did not enhance ecdysone secretion. Thus, although the prothoracic glands are insulin-responsive and insulin-like hormones may promote glandular growth as larvae feed, the effects of nutritional depletion on steroidogenesis in Manduca cannot be explained solely by reduced insulin.
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Affiliation(s)
- Amy L Walsh
- Department of Biology, Northeastern University, 360 Huntington Avenue, 134 Mugar Building, Boston, MA 02115, USA.
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7
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Smith W, Priester J, Morais J. PTTH-stimulated ecdysone secretion is dependent upon tyrosine phosphorylation in the prothoracic glands of Manduca sexta. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2003; 33:1317-1325. [PMID: 14599503 DOI: 10.1016/j.ibmb.2003.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
PTTH stimulates ecdysteroid secretion by the insect prothoracic glands. The peptide activates cAMP synthesis in a calcium-dependent manner, ultimately enhancing ecdysteroid synthesis. We have found that PTTH stimulates a rapid increase in tyrosine phosphorylation of at least four proteins in the prothoracic glands of larval Manduca sexta, as seen on Western blots of glandular lysates probed with antibody directed against phosphotyrosine. PTTH-stimulated tyrosine phosphorylation is blocked by an inhibitor of Src family tyrosine kinases, 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]-pyrimidine (PP1). The inhibitor also blocks PTTH-stimulated ecdysone secretion, as well as PTTH-stimulated cAMP synthesis. Direct activation of the catalytic subunit of adenylyl cyclase by forskolin is not affected by PP1. In addition, ecdysteroid secretion stimulated by the cAMP analog dbcAMP is not blocked by PP1. These findings point to an important role for a Src-family tyrosine kinase at a very early step in the PTTH signaling pathway, prior to the activation of adenylyl cyclase.
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Affiliation(s)
- Wendy Smith
- Department of Biology, Northeastern University, 433 Richards Hall, 360 Huntington Avenue, Boston, MA 02115, USA.
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8
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Gilbert LI, Rybczynski R, Warren JT. Control and biochemical nature of the ecdysteroidogenic pathway. ANNUAL REVIEW OF ENTOMOLOGY 2002; 47:883-916. [PMID: 11729094 DOI: 10.1146/annurev.ento.47.091201.145302] [Citation(s) in RCA: 336] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Molting is elicited by a critical titer of ecdysteroids that includes the principal molting hormone, 20-hydroxyecdysone (20E), and ecdysone (E), which is the precursor of 20E but also has morphogenetic roles of its own. The prothoracic glands are the predominate source of ecdysteroids, and the rate of synthesis of these polyhydroxylated sterols is critical for molting and metamorphosis. This review concerns three aspects of ecdysteroidogenesis: (a) how the brain neuropeptide prothoracicotropic hormone (PTTH) initiates a transductory cascade in cells of the prothoracic gland, which results in an increased rate of ecdysteroid biosynthesis (upregulation); (b) how the concentrations of 20E in the hemolymph feed back on the prothoracic gland to decrease rates of ecdysteroidogenesis (downregulation); and (c) how the prothoracic gland cells convert cholesterol to the precursor of E and then 20E, a series of reactions only now being understood because of the use of a combination of classical biochemistry and molecular genetics.
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Affiliation(s)
- Lawrence I Gilbert
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3280, USA.
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9
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Rybczynski R, Bell SC, Gilbert LI. Activation of an extracellular signal-regulated kinase (ERK) by the insect prothoracicotropic hormone. Mol Cell Endocrinol 2001; 184:1-11. [PMID: 11694336 DOI: 10.1016/s0303-7207(01)00664-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Ecdysteroid hormones are crucial in controlling the growth, molting and metamorphosis of insects. The predominant source of ecdysteroids in pre-adult insects is the prothoracic gland, which is under the acute control of the neuropeptide hormone prothoracicotropic hormone (PTTH). Previous studies using the tobacco hornworm, Manduca sexta, have shown that PTTH stimulates ecdysteroid synthesis via a series of events, including the activation of protein kinase A and the 70 kDa S6 kinase (p70(S6k)). In this study, PTTH was shown to stimulate also mitogen-activated protein kinase (MAPK) phosphorylation and activity in the Manduca prothoracic gland. The MAPK involved appears to be an extracellular signal-regulated kinase (ERK) homologue. The ERK phosphorylation inhibitors PD 98059 and UO 126 blocked basal and PTTH-stimulated ERK phosphorylation and ecdysteroid synthesis. PTTH-stimulated ERK activity may be important for both rapid regulation of ecdysteroid synthesis and for longer-term changes in the size and function of prothoracic gland cells.
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Affiliation(s)
- R Rybczynski
- Department of Biology, Coker Hall CB# 3280, University of North Carolina at Chapel Hill, 27599-3280, USA.
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10
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Birkenbeil H. Pharmacological study of signal transduction during stimulation of prothoracic glands from Manduca sexta. JOURNAL OF INSECT PHYSIOLOGY 2000; 46:1409-1414. [PMID: 10878267 DOI: 10.1016/s0022-1910(00)00064-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Cytosolic free calcium, [Ca(2+)](i), measured in individual prothoracic gland cells of Manduca sexta with Fura-2 was increased by prothoracicotropic hormone, PTTH, and by mastoparan, a wasp venom peptide, activating G proteins. The effect on [Ca(2+)](i) of mastoparan and of PTTH was inhibited by cadmium and the antagonist of T-type calcium channels, amiloride, and not influenced by the L-type calcium channel blocker nitrendipine, suggesting that the same or similar plasma membrane channels are involved in the action of mastoparan and of PTTH. Pertussis toxin prevented the mastoparan-induced increase of [Ca(2+)](i), whereas the effect of PTTH is not influenced by pertussis toxin. Intracellular addition of GDP-beta-S failed to inhibit the PTTH-stimulated increase in [Ca(2+)](i) suggesting that G proteins are not involved in the stimulatory mechanism of PTTH.
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Affiliation(s)
- H Birkenbeil
- Sächsische Akademie der Wissenschaften zu Leipzig, AG Neurohormonale Wirkungsmechanismen, Erbert-Str.1 PF 100322, 07703, Jena, Germany
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11
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Rybczynski R, Gilbert LI. Cloning of a beta1 tubulin cDNA from an insect endocrine gland: developmental and hormone-induced changes in mRNA expression. Mol Cell Endocrinol 1998; 141:141-51. [PMID: 9723895 DOI: 10.1016/s0303-7207(98)00083-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A rapid increase in ecdysteroid hormone synthesis results when the insect prothoracic gland is stimulated with prothoracicotropic hormone (PTTH), a brain neuropeptide hormone. PTTH also stimulates the specific synthesis of several proteins, one of which is a beta tubulin. To further understand the possible roles of beta tubulin in the prothoracic gland, beta tubulin cDNA clones were isolated from a tobacco hornworm (Manduca sexta) gland cDNA library. Sequence analysis indicated that these clones were assignable to the beta1 tubulin isoform. Gland beta1 tubulin mRNA levels during the last larval instar and early pupal-adult development exhibited peaks that coincided with peaks in ecdysteroid synthesis. Manipulations of the glands hormonal milieu showed that beta1 tubulin mRNA levels respond to 20 hydroxyecdysone and PTTH. The data also support our earlier proposal that the prothoracic gland beta1 tubulin gene is ubiquitously expressed but exhibits tissue- and developmental-specific regulation of transcription and translation.
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Affiliation(s)
- R Rybczynski
- Department of Biology, University of North Carolina at Chapel Hill, 27599, USA.
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12
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Harvie PD, Filippova M, Bryant PJ. Genes expressed in the ring gland, the major endocrine organ of Drosophila melanogaster. Genetics 1998; 149:217-31. [PMID: 9584098 PMCID: PMC1460132 DOI: 10.1093/genetics/149.1.217] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We have used an enhancer-trap approach to begin characterizing the function of the Drosophila endocrine system during larval development. Five hundred and ten different lethal PZ element insertions were screened to identify those in which a reporter gene within the P element showed strong expression in part or all of the ring gland, the major site of production and release of developmental hormones, and which had a mutant phenotype consistent with an endocrine defect. Nine strong candidate genes were identified in this screen, and eight of these are expressed in the lateral cells of the ring gland that produce ecdysteroid molting hormone (EC). We have confirmed that the genes detected by these enhancer traps are expressed in patterns similar to those detected by the reporter gene. Two of the genes encode proteins, protein kinase A and calmodulin, that have previously been implicated in the signaling pathway leading to EC synthesis and release in other insects. A third gene product, the translational elongation factor EF-1alpha F1, could play a role in the translational regulation of EC production. The screen also identified the genes couch potato and tramtrack, previously known from their roles in peripheral nervous system development, as being expressed in the ring gland. One enhancer trap revealed expression of the gene encoding the C subunit of vacuolar ATPase (V-ATPase) in the medial cells of the ring gland, which produce the juvenile hormone that controls progression through developmental stages. This could reveal a function of V-ATPase in the response of this part of the ring gland to adenotropic neuropeptides. However, the gene identified by this enhancer trap is ubiquitously expressed, suggesting that the enhancer trap is detecting only a subset of its control elements. The results show that the enhancer trap approach can be a productive way of exploring tissue-specific genetic functions in Drosophila.
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Affiliation(s)
- P D Harvie
- Developmental Biology Center, University of California, Irvine, California 92697-2275, USA
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13
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Birkenbeil H. Intracellular calcium in prothoracic glands of Manduca sexta. JOURNAL OF INSECT PHYSIOLOGY 1998; 44:279-286. [PMID: 12769962 DOI: 10.1016/s0022-1910(97)00115-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Cytosolic free calcium was measured in individual prothoracic gland cells of Manduca larvae with Fura-2. During the last larval instar there was no correlation between intracellular calcium concentration and ecdysteroid secretion by the glands. The addition of prothoracicotropic hormone (PTTH) from brains of Manduca larvae to prothoracic glands in vitro resulted in a significant increase in the calcium concentration of the gland cells. The effect of PTTH was inhibited by the inorganic calcium channel antagonists, cadmium, lanthanum and nickel, and by the antagonist of T-type calcium channels, amiloride, whereas all the other antagonists tested failed to block the action of PTTH. TMB-8, an inhibitor of intracellular calcium mobilization, did not reduce the PTTH-induced rise in calcium, which suggests that IP(3)-dependent intracellular calcium stores are not involved in the calcium-mediated stimulation of ecdysteroid synthesis. Moreover, PTTH is thought to increase intracellular calcium in prothoracic glands of Manduca by influencing calcium channels in the plasma membrane.
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Affiliation(s)
- H Birkenbeil
- Saxon Academy of Sciences at Leipzig, AG Prof. Dr. H. Penzlin, Erbertstr.1 PF 100322, 07703, Jena, Germany
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14
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Dai JD, Gilbert LI. Programmed cell death of the prothoracic glands of Manduca sexta during pupal-adult metamorphosis. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 1997; 27:69-78. [PMID: 9061930 DOI: 10.1016/s0965-1748(96)00068-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The degeneration of the prothoracic glands of Manduca sexta during pupal-adult metamorphosis was analyzed by both light and transmission electron microscopy, and correlated with a functional analysis of the ability of the prothoracic glands to synthesize ecdysteroids in vitro. Apoptosis of degenerating glandular cells was also examined by in situ indirect immunofluorescein detection of digoxigenin-labeled genomic DNA cleavage (the TUNEL method). The ability of the prothoracic gland to synthesize ecdysteroids reached a peak 4 days after pupation, decreased drastically on day 6 and then decreased further to the basal level 2 days later. Prothoracic gland degeneration was initiated on day 6 and was characterized by nuclear condensation, cytoplasmic budding, giant autophagic vacuoles, the disappearance of the smooth endoplasmic reticulum and intercellular channels, and the fragmentation of the cytoplasm into membrane-bound bodies. The cell debris of these degenerating cells was then engulfed by numerous phagocytic hemocytes. The results of the analysis of apoptosis by immunofluorescence detection are in complete accord with the histological, ultrastructural and radioimmunoassay data, suggesting that apoptosis is the basic mechanism for programmed cell death of the cells comprising these vital glands.
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Affiliation(s)
- J D Dai
- Department of Biology, University of North Carolina at Chapel Hill 27599-3280, USA
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15
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Watson RD, Ackerman-Morris S, Smith WA, Watson CJ, Bollenbacher WE. Involvement of microtubules in prothoracicotropic hormone-stimulated ecdysteroidogenesis by insect (Manduca sexta) prothoracic glands. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1996; 276:63-9. [PMID: 8828185 DOI: 10.1002/(sici)1097-010x(19960901)276:1<63::aid-jez7>3.0.co;2-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Secretion of ecdysteroid molting hormones by insect prothoracic glands is stimulated by neuropeptide prothoracicotropic hormones (PTTH). Studies reported here were conducted to assess the effects of microfilament and microtubule inhibitors on in vitro ecdysteroidogenesis by prothoracic glands of Manduca sexta. Microfilament inhibitors (cytochalasins B and D) had no effect on basal or big PTTH-stimulated ecdysteroidogenesis. Microtubule inhibitors (colchicine, podophyllotoxin, nocodazole) had no effect on basal ecdysteroid secretion, but suppressed PTTH-stimulated secretion in a concentration-dependent manner. The effect of nocodazole was partially reversible, suggesting it was not due to nonspecific toxicity. Colchicine had no effect on glandular ecdysteroid levels, indicating that inhibition was not due solely to blockage of secretion. The combined results are consistent with the hypothesis that microtubule-mediated transport of ecdysteroid precursors plays a critical role in stimulation of ecdysteroidogenesis by PTTH.
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Affiliation(s)
- R D Watson
- Department of Biology, University of Alabama at Birmingham 35294, USA
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Smith WA. Regulation and consequences of cellular changes in the prothoracic glands of Manduca sexta during the last larval instar: a review. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 1995; 30:271-293. [PMID: 7579575 DOI: 10.1002/arch.940300214] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The prothoracic glands of the tobacco hornworm, Manduca sexta, respond to prothoracicotropic hormone (PTTH) by a regulatory pathway involving cAMP, protein phosphorylation, protein synthesis, and enhanced secretion of ecdysteroids including ecdysone and 3-dehydroecdysone. Recent investigations have revealed that PTTH acts by this general mechanism throughout the fifth larval instar, i.e., during the transition from larva to pupa. However, the glands undergo developmental changes in size, steroidogenic capacity, and in elements of the signalling pathway associated with synthesis, degradation, and intracellular action of cAMP. The present review describes such changes, and their possible regulation and consequences, in the general context of endocrine events underlying larval-pupal metamorphosis during the fifth larval stage.
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Affiliation(s)
- W A Smith
- Department of Biology, Northeastern University, Boston, Massachusetts 02115, USA
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Hartfelder K, Hanton WK, Bollenbacher WE. Diapause-dependent changes in prothoracicotropic hormone-producing neurons of the tobacco hornworm, Manduca sexta. Cell Tissue Res 1994; 277:69-78. [PMID: 8055540 DOI: 10.1007/bf00303082] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The prothoracicotropic hormone (PTTH), which stimulates ecdysteroid synthesis in the prothoracic glands, is produced, in the dorso-lateral protocerebrum of Manduca sexta, by paired peptidergic neurons, the lateral neurosecretory cell group III (L-NSC III). Our study revealed ultrastructural features of L-NSC III, identified by immunogold labeling, and compared developing and diapause states. In developing and early-diapause pupae, L-NSC III soma ultrastructure is similar and is characterized by numerous clusters of neurosecretory granules (NSG) and an extensive trophospongium formed by satellite-glial cells. However, as diapause progresses, the ultrastructure changes, with the NSG becoming concentrated into large clusters separated by highly organized rough endoplasmic reticulum. Most conspicuous is a substantial reduction in the number of Golgi complexes and the glial trophospongium, and the presence of stacked plasma membrane separating the glia and neuron somata. The deep-diapause soma also has abundant glycogen deposits and autophagic vacuoles. With diapause termination, this morphology reverts to the nondiapause ultrastructure within three days, i.e. just before PTTH release that evokes development to the adult. During PTTH release the abundance of NSG in the soma does not change, suggesting that NSG depletion in the perikarya is not a marker for neurosecretion by the L-NSC III.
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Affiliation(s)
- K Hartfelder
- Zoologisches Institut, Universität Tübingen, Germany
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DAI JIDA, COSTELLO MJOSEPH, GILBERT LAWRENCEI. The prothoracic glands ofManduca sexta:a microscopic analysis of gap junctions and intercellular bridges. INVERTEBR REPROD DEV 1994. [DOI: 10.1080/07924259.1994.9672375] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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