0000000000306895
AUTHOR
Lawrence I. Gilbert
Woc (without children) gene control of ecdysone biosynthesis in Drosophila melanogaster.
Abstract The first step in ecdysteroidogenesis, i.e. the 7,8-dehydrogenation of dietary cholesterol (C) to 7-dehydrocholesterol (7dC), is blocked in Drosophila melanogaster homozygous woc (without children) third instar larval ring glands (source of ecdysone). Unlike ring glands from wild-type D. melanogaster larvae, glands from woc mutants cannot convert radiolabelled C or 25-hydroxycholesterol (25C) to 7dC or 7-dehydro-25-hydroxycholesterol (7d25C) in vitro, nor to ecdysone (E). Yet, when these same glands are incubated with synthetic tracer 7d25C, the rate of metabolism of this polar Δ5,7-sterol into E is identical to that observed with glands from comparably staged wild-type larvae. The…
The Mutation without childrenrgl Causes Ecdysteroid Deficiency in Third-Instar Larvae of Drosophila melanogaster
Larvae homozygous for the recessive lethal allele without children(rgl) (woc(rgl)) fail to pupariate. Application of exogenous 20-hydroxyecdysone elicits puparium formation and pupation. Ecdysteroid titer measurements on mutant larvae show an endocrine deficiency in the brain-ring gland complex, which normally synthesizes ecdysone, resulting in a failure of the larvae to achieve a threshold whole body hormone titer necessary for molting. Ultrastructural investigation revealed extensive degeneration of the prothoracic cells of the ring gland in older larvae. The woc gene, located in polytene chromosomal region 97F, consists of 11 exons. A 6.8-kb transcript is expressed throughout development…
An Incremental Analysis of the Embryonic Development of the Tobacco Hornworm,Manduca sexta
Summary A timetable of the embryonic development of Manduca sexta has been compiled to serve as a basis for physiological studies. Embryogenesis is complete within 117 hr at 24° C and was analyzed by examining specimens representing 20 stages, i.e. intervals of 5% of the total developmental time. Stage 0 denotes the newly deposited egg. Germ band formation, gastrulation, differentiation of tissues and organs, and blastokinesis are described in detail. By stage 1 (6 hr post-oviposition) the cellular blastoderm is evident and the presumptive serosal and embryonic cells are distinguishable. At stage 2 the germ band has separated from the blastoderm, and by stage 3 it has elongated enormously, …