The Drosophila disembodied gene controls late embryonic morphogenesis and codes for a cytochrome P450 enzyme that regulates embryonic ecdysone levels

Abstract

Ecdysteroids regulate a wide variety of cellular processes during arthropod development, yet little is known about the genes involved in the biosynthesis of these hormones. Previous studies have suggested that production of 20-hydroxyecdysone in Drosophila and other arthropods involves a series of cytochrome P450 catalyzed hydroxylations of cholesterol. In this report, we show that the disembodied (dib) locus of Drosophila codes for a P450-like sequence. In addition, we find that dib mutant embryos have very low titers of ecdysone and 20-hydroxyecdysone (20E) and fail to express IMP-E1 and L1, two 20E-inducible genes, in certain tissues of the embryo. In situ hybridization studies reveal that dib is expressed in a complex pattern in the early embryo, which eventually gives way to restricted expression in the prothoracic portion of the ring gland. In larval and adult tissues, dib expression is observed in the prothoracic gland and follicle cells of the ovaries respectively, two tissues known to synthesize ecdysteroids. Phenotypic analysis reveals that dib mutant embryos produce little or no cuticle and exhibit severe defects in many late morphogenetic processes such as head involution, dorsal closure and gut development. In addition, we examined the phenotypes of several other mutants that produce defective embryonic cuticles. Like dib, mutations in the spook (spo) locus result in low embryonic ecdysteroid titers, severe late embryonic morphological defects, and a failure to induce IMP-E1. From these data, we conclude that dib and spo likely code for essential components in the ecdysone biosynthetic pathway and that ecdysteroids regulate many late embryonic morphogenetic processes such as cell movement and cuticle deposition.

Proteomic and Bioinformatic Analysis on Endocrine Organs of Domesticated Silkworm, Bombyx mori L. for a Comprehensive Understanding of Their Roles and Relations

“…During larval and pupal stages of insects, one of the most important steroid hormones is ecdysone, which is synthesized in the PG and plays a central role in the control of larval development. In this study, two players Cyp302a1 57,58 and Rieske-domain protein Neverland, 59 which are involved in the biosynthesis of ecdysteroids, were identified among the PG-specific proteins (Supplemental Table 6). POU domain proteins which play an important role in transcriptional regulation of the Bom-DH-PBAN gene 60 were also found.…”

Drosophila Embryogenesis Scales Uniformly across Temperature in Developmentally Diverse Species

“…One possibility is that there is an actual clock -some molecule or set of molecules whose abundance or activity progresses in a clocklike manner across embryogenesis and is read out to trigger the myriad different processes that occur in the transition from a fertilized egg to a larvae. However there is no direct evidence that such a clock exists (although we note that there is a pulse of ecdysone during embryogenesis with possible morphological functions [28,29]). A more likely explanation is that there is a common rate limiting process throughout embryogenesis.…”

Cyromazine Effects the Reproduction of Drosophila by Decreasing the Number of Germ Cells in the Female Adult Ovary

“…In D. melanogaster , ecdysteroids control larval development [ 29 , 30 ]. Whereas, in adults, these hormones are found to be essential for proper oogenesis [ 31 , 32 ].…”

“…In Drosophila , the application of cyromazine increased larval mortality, while the exogenous treatment of 20E decreased larval mortality. Further, 20E treatment together with cyromazine increased the early eclosion of adult flies [ 30 ]. In the present study, we observed a 27% decrease in the number of GSCs after treatment with cyromazine.…”