Becky A. Sage

Ecdysone titers during postembryonic development of Drosophila melanogaster

Abstract The level of ecdysone in Drosophila melanogaster was determined by a radioimmune assay in organisms selected between the second larval instar and maturity. Maxima in the titer of the hormone were observed at puparium formation and 38 hr later, just prior to the secretion of the adult cuticle. The level of ecdysone was very low in adults of either sex. However, adult females had significantly more ecdysone per organism than did males. The magnitude of this difference could be correlated with ovarian development, suggesting a possible role for ecdysone in ovarian maturation in this organism.

A high affinity antiserum specific for the ecdysone nucleus

Abstract The 22-hemisuccinate ester of α-ecdysone was conjugated to bovine thyroglobulin and used to raise an antiserum which has a greater affinity for α-ecdysone and an overall higher sensitivity than those antisera previously reported. Modification of the tetracyclic nucleus characteristic of the ecdysones by either hydroxylation or dehydroxylation appreciably diminishes the ability of the ecdysone to compete for the antibody binding sites. Deviations from the side chain structure of α-ecdysone also reduce the affinity of such molecules (e.g. β-ecdysone, ponasterone A and inokosterone) but to a significantly lesser degree than alteration of the tetracyclic nucleus.

The qualitative and quantitative determinations of ecdysones in tissues of the crab, Pachygrapsus crassipes, following molt induction

On the basis of chromatographic evidence, it appears that the major circulating molting hormone is β-ecdysone in the crab, Pachygrapsus crassipes. This circulating molting hormone does not appear to be bound to any carrier protein in the hemolymph. The effects of eyestalk extirpation and the removal of the Y-organ upon the tissue distribution of ecdysone are documented using a radioimmunoassay. From in vitro experiments, it is demonstrated that crab tissues have the ability to convert radiolabeled α- to β-ecdysone. Of the tissues examined, the testis appears to have the greatest capacity for this conversion.

Endocrine regulation of ovarian development in the autogenous mosquito, Aedes atropalpus.

Abstract The mosquito Aedes atropalpus is autogenous, i.e., normal ovarian development proceeds in adult females without any exogenous source of protein. Using a radioimmunoassay (RIA) for ecdysone, it was found that the titer of antigen-positive material in whole-body extracts of adult females rose from about 150 pg equiv of β-ecdysone per female at eclosion to an average peak value of 323 pg 32 hr later. The titer then dropped to approximately 100 pg over the next 16 hr. A comparison of the RIA titer with follicle size, vitellin deposition into oocytes, and total extractable soluble proteins from ovaries suggested a causal relationship between the hormone titer and normal ovarian development. Preliminary data also suggest that the ovary is a source of ecdysteroid in these adult animals. Decapitation of adult females from 0 to 4 hr after eclosion completely prevented ovarian development. Animals decapitated 30 min after eclosion and then assayed for ecdysteroid content 32 hr later revealed a hormonal titer 75% less than normal intact controls. An analysis of the 32-hr RIA-positive material by high-pressure liquid chromatography confirmed the presence of β-ecdysone but did not detect any α-ecdysone. Ovarian deficiencies incurred by decapitation were partially restored by injection with β-ecdysone or by topical application of juvenile hormone.

A positive correlation between oocyte production and ecdysteroid levels in adult Aedes

ABSTRACT. The ecdysteroid titre of adult females resulting from a cross of Aedes epactius females, an anautogenous mosquito, with Aedes atropalpus males (an autogenous strain) was determined using a radioimmunoassay. The F1 hybrid is autogenous and produces mature oocytes without the benefit of a blood‐meal. The ecdysteroid profile of this hybrid revealed a smaller early peak and a second larger one. Qualitatively the overall hormonal profile appeared quite similar to the ones previously obtained using A.atropalpus females and blood‐fed A.aegypti. Quantitatively, the amount of endogenous hormone exhibited, and the total number of mature oocytes produced, may be positively correlated.

An affinity column for ecdysone binding proteins.

Abstract Under basic conditions β-ecdysone can be covalently linked to the oxirane residue of epoxy-activated Sepharose 6B. Such an ecdysone-modified column matrix retards antibodies to β-ecdysone while permitting, however, the free passage of other antibodies in rabbit antiserum. The bound anti-ecdysone antibodies can subsequently be eluted by a low pH (3.8), high salt (0.5 m ) buffer. The utility of such an affinity column for the isolation of ecdysone receptors is discussed.