ABSTRACT
High specific activity tritiated ecdysone precursor, 2,22,25-trideoxyecdysone, was incubated with Y-organs from intermoult and premoult shore crabs. Several metabolites were identified among which ecdysone and 25-deoxyecdysone. The concomitant production of these 2 molecules by Y-organs and their subsequent hydroxylation at C-20 by peripheral tissues, provide an explanation for the presence of both 20-hydroxyecdysone and ponasterone A (25-deoxy-20-hydroxyecdysone) in the circulating haemolymph of crabs.
Subject(s)
Brachyura/metabolism , Cholestenones , Ecdysone/biosynthesis , Animals , Chromatography, High Pressure Liquid , Ecdysone/analogs & derivatives , Ecdysone/metabolism , Ecdysterone/analogs & derivatives , Ecdysterone/metabolism , Endocrine Glands/metabolism , KineticsABSTRACT
A high specific activity tritiated ecdysone precursor, 2,22,25-trideoxyecdysone, was used to probe the capacity of various embryonic and larval tissues to perform the last 3 hydroxylation steps in ecdysone biosynthesis. Embryos at early stages of development, prior to the differentiation of their endocrine glands and embryonic heads, thoraces and abdomens of later stages, were found to have the capacity to hydroxylate the precursor to ecdysone. Larval epidermis and fat body are also able to transform 2,22,25-trideoxyecdysone into ecdysone; Malpighian tubules and midgut hydroxylate the precursor at C-2 but are apparently unable to hydroxylate both at C-22 and C-25. Larval prothoracic glands convert the precursor to ecdysone at a very efficient rate, which is 1-2 magnitudes higher than that of the other tissues investigated; several data argue for the existence of a privileged sequence of hydroxylations, C-25, C-22, C-2, in the larval prothoracic glands.
Subject(s)
Cholestenones , Ecdysone/analogs & derivatives , Ecdysone/biosynthesis , Grasshoppers/metabolism , Abdomen , Animals , Chromatography, High Pressure Liquid , Ecdysone/metabolism , Epidermis/metabolism , Fat Body/metabolism , Grasshoppers/embryology , Head , Hydroxylation , Larva/metabolism , Malpighian Tubules/metabolism , ThoraxABSTRACT
The European eel's oesophagus, stomach and anterior and posterior intestine were perfused separately, in vivo. The oesophagus and anterior intestine play a major part in processing of ingested water. Serosal potential differences to mucosal measured in vivo were positive in all gut segments. The C1- concentrations of luminal contents in different parts of the gut were measured in nine species of sea-water teleosts. The progressive decrease in C1- concentration resulted from local processing of the ingested sea water, and the beginnings of the oesophagus and of the intestine were the major processing sites.