Conversion of a Radiolabelled Putative Ecdysone Precursor, 2,22,25-Trideoxyecdysone (5β-Ketodiol) in Larvae and Pupae ofCalliphora vicina

Abstract

When a tritiated ecdysone precursor, 2,22,25-trideoxyecdysone (5,8-ketodiol) was injected into larvae and pupae of Calliphora vicina, it was efficiently converted into 20-hydroxyecdysone. Injections into the anterior and posterior compartments of neck-ligated larvae have shown that both parts can hydroxylate the 5,8-ketodiol at C-25, C-22 and C-2 to form ecdysone which was readily hydroxylated at C-20 to form 20-hydroxyecdysone. When incubated with larval brain-ring gland complexes, 5,8-ketodiol was converted to ecdysone as well as to other metabolites, such as 22,25-dideoxyecdysone and 2-deoxyecdysone. Other larval tissues, namely the fat body, Malpighian tubules, gut and carcass are also able to transform 5,8-ketodiol into ecdysone in vitro, which explains the conversion of the 5Q-ketodiol injected into the abdominal portions of neck-ligated larvae. The large tissue distribution of the enzyme systems involved in the terminal hydroxylations of ecdysteroid biosynthesis in discussed in view of the results obtained in this and other insect orders. ecdysone biosynthesis, ring gland, Calliphora, blowfly, radio-labelled 5,8-ketodiol 0168-8170/87/$03.50 1Cl1987 Balaban

Phantom encodes the 25-hydroxylase of Drosophila melanogaster and Bombyx mori: a P450 enzyme critical in ecdysone biosynthesis

“…Using this sensitive technique, strong expression is observed in the larval ring gland and adult ovary, although faint expression can also be observed in the larval brain and fat body and adult head and carcass from either sex. This supports the biochemical data of earlier studies using enzyme extracts indicating that the 25-hydroxylation reaction, while prominent in the prothoracic glands, can also be detected in several non-endocrine tissues in both Calliphora and Locusta (Meister et al, 1985(Meister et al, , 1987see Delbecque et al, 1990). Recent data from transgenic flies expressing GFP under the control of a putative Dmphm gene promoter support these findings, as significant expression was observed not only in the larval and mid-pharate-adult prothoracic gland cells and adult ovarian follicle cells as expected, but also in a small subset of cells within the tissues of the abdominal muscle or epidermis during larval and pupal-adult development.…”

Expression of genes encoding proteins involved in ecdysteroidogenesis in the female mosquito, Aedes aegypti

“…8) in part supports our finding that these tissues are capable of limited ecdysteroid production after a blood meal. Of particular relevance, the larval gut, integument and carcass of L. migratoria and the blowfly, Calliphora vicina, were shown to synthesize ecdysteroids from the precursor 5b-ketodiol, suggesting the presence of enzymes that conduct the terminal hydroxylation reactions on C-25, C-22 and C-2 (Meister et al, 1985(Meister et al, , 1987 and supporting our finding that AedaeCYP302a1 and AedaeCYP315a1 are expressed in same tissues of female A. aegypti. Transcripts for many of the genes were also present in males (Fig.…”

Study of steroidogenesis in pupae of the forensically important blow fly Protophormia terraenovae (Robineau-Desvoidy) (Diptera: Calliphoridae)

“…The presence of both ecdysone and 20-hydroxyecdysone in pupae of two Calliphora species has been demonstrated [12] and ecdysteroid metabolism has been extensively studied in the blue blow fly Calliphora vicina (review in refs. [11,13]). In P. terraenovae, only ecdysteroids present in adult females have so far been studied [14,15].…”