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Insect Biochem Mol Biol. 2016 Mar;70:160-9. doi: 10.1016/j.ibmb.2016.01.001. Epub 2016 Jan 7.

Calcium influx enhances neuropeptide activation of ecdysteroid hormone production by mosquito ovaries.

Author information

1
Department of Entomology, University of Georgia, Athens, GA 30602, USA.
2
Department of Entomology, University of Georgia, Athens, GA 30602, USA. Electronic address: mrbrown@uga.edu.

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.

KEYWORDS:

Aedes aegypti; Bombyx mori; Insulin-like peptide; Ovary ecdysteroidogenic hormone; Prothoracic gland; Prothoracicotropic hormone

PMID:
26772671
PMCID:
PMC4767660
[Available on 2017-03-01]
DOI:
10.1016/j.ibmb.2016.01.001
[Indexed for MEDLINE]
Free PMC Article

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