Precocene II metabolism: Comparative in vivo studies among several species of insects,and structure elucidation of two major metabolites

Several species of insects, exhibiting varying responsiveness to the juvenile hormone antagonist precocene II (6,7-dimethoxy-2,2-dimethylchromene), were challenged topically with a tritiated preparation of the title compound. Metabolism of [³H]precocene II was subsequently examined by withdrawing hemolymph samples from treated animals at appropriate time intervals and characterizing the extractable radiolabel chromatographically. Quantitative (or qualitative) differences observed between the respective metabolic profiles were found not correlative with specimen sensitivity to precocene. Production of two heretofore unreported metabolites, identified by spectral and chemical means as O-β-glucosides of 6- and 7-monodemethylated precocene II, was demonstrated in both sensitive and insensitive species. No evidence for the presence of a hemolymphborne, biologically effective “activated metabolite” produced in vivo by precocene-susceptible insects could be found. The latter finding may well argue for in situ bioactivation of precocene at the target tissue(s) by these sensitive insects.     

The effect of some Frescon analogs on the aquatic snail,Lymnaea stagnalis: II. Correlation of neurotoxicity to Molluscicidal effectiveness

Although the molluscicide Frescon is a strong neurotoxin to the Lymnaea stagnalis central nervous system in vitro, it is probable that the exposure of the whole animal to this molluscicide fails to result in central nervous system abnormalities: Frescon does not appear to reach the brain in sufficient quantity to disrupt its normal activity. However, only those Frescon analogs found to be neurotoxic were molluscicidal, suggesting some related mode, if not site, of action. Frescon and its analogs may act by affecting excitable tissues other than the nervous system (e.g., the snail musculature) by altering certain functional and/or structural membrane properties.     

Studies on the avian shell gland during egg formation: The effect of acetazol‐amide on the transfer of ions to the albumen 1

1. Twenty‐five laying hens were fed on a diet containing 100 mg acetazolamide/kg in order to determine the effects of a decrease in the activity of carbonic anhydrase on the transfer of minerals to the egg albumen.

2. Treatment with acetazolamide decreased the rate of shell formation by 44%; reduced the concentrations of water and Na+ in the albumen at the beginning of the plumping stage but increased the accumulation of water during plumping; increased the concentration of Cl‐ in the albumen after the 6‐h stage without any appreciable change in K+ and Ca²⁺ concentrations.

3. The computed relationships between the concentrations of different ions also showed that the transfer of water and Na+ were linked during egg formation, that a water‐independent, acetazolamide‐sensitive reabsorption of Na+ occurred after the 10‐h stage and that Na+ and Cl‐moved simultaneously up to 14 h but with the ratio of Cl‐ to Na+ three times higher in the treated group.

4. It is concluded that acetazolamide impairs the transfer of Na+ and Cl‐ between the albumen and the extracellular fluid and that secretion of Ca²⁺ into the uterine lumen seems to depend on Na+ and Cl‐ reabsorption.