Ecdysteroids are synthesized by ovaries of female Aedes aegypti following a blood meal, which promotes fat body production of vitellogenin. The full ecdysteroid biosynthetic pathway is not known, but various proteins involved in the biosynthetic process have been identified by analysis of Drosophila ecdysteroid mutants and by diverse biochemical and molecular techniques in other insect species. The intracellular pathway of ecdysteriod biosynthesis by insect tissues is believed to mimic vertebrate steroidogenesis in that precursor steroid molecules shuttle between the endoplasmic reticulum and the inner mitochondrial membrane during processing. Several genes of interest were identified from ovary cDNA amplified by PCR using degenerate primers designed to conserved stretches of amino acids in proteins functionally characterized for D. melanogaster or other animals, and gleaned from the Anopheles gambiae genomic database: the transport proteins, diazepam-binding inhibitor and steroidogenic acute regulatory protein; the enzyme for shuttling electrons to P450 enzymes, adrenodoxin reductase; and enzymes involved in steroid modification, 3-dehydroecdysone 3b-reductase and 22-hydroxylase. Gene transcript levels in ovaries were analyzed by RT-PCR and real-time PCR before and after a blood meal, and after incubation with agents known to stimulate ecdysteroidogenesis.
Species 1: Diptera Culicidae Aedes aegypti (yellow fever mosquito)
Keywords: hormones
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