THE USE OF A JUVENILE-HORMONE BINDING-PROTEIN FOR THE QUANTITATIVE ASSAY OF JUVENILE-HORMONE

The suitability of the haemolymph juvenile hormone binding protein (JH BP) of Locusta migratoria for use in a competition assay for juvenile hormone (JH) III has been investigated, and a simple quantitative assa y procedure using this protein has been developed. JHBP partially puri fied from haemolymph of precocene treated adult locusts gives rapid an d stable binding of [H-3]10R-JH III, and can be separated from the unb ound hormone with hydroxylapatite (HAP), The sensitivity of the method is such that 0.15 pmol (40 pg) 10R-JH III gives 50% displacement of [ H-3]10R-JH III from the binding protein, Competition by JH II is about 5 times less and JH I about 10 times less than that by JH III, while JH III diol and acid compete at least 1000 times less strongly. A proc edure for extraction and assay of JH from 50 mu l haemolymph samples i s described, the interference by non-specific haemolymph components is shown to be relatively small, and some data on JH III titres in matur ing adult locusts are presented.