A radioimmunological assay for naturally occurring insect juvenile hormones using iodinated tracers : Its use in the analysis of biological samples

Three sensitive and specific radioimmunological assays (RIA) using iodinated tracers have been developed for the quantitative measurement of naturally occurring juvenile hormone (JH). The antigens were prepared by binding the JH’s to human serum albumin. lodinated tracers were prepared by binding histamine to the JH molecule, and then subsequently binding one molecule of 125 per molecule of histamine. The RIA’s were carried out in 0.02 M phosphate buffer containing 0.1 p.100 of BSA. The assay detection limit was 20 pg for all the three juvenile hormones. RIA sensitivity (at B/BO = 50 p. 100) of JH I, JH, and JH, was 0.75, 1 and 2.6 ng/ml, respectively. Antiserum to JH 1 cross-reacted 7.3 p. 100 with J H 2 and 0.8 p. 100 with JH! ; antiserum to J H 2 cross-reacted 26 p. 100 with JH, and 12 p. 100,with JH 3, and antiserum to JH, cross-reacted 0.3 p. 100 with JH, and 0.9 p. 100 with JH 2’ Various methods of preparing biological samples for the RIA of JH’s have been described.