3.5. Measuring the rate of juvenile hormone biosynthesis by the paired corpora allata
This protocol describes a rapid partition radiochemical assays for quantifying rates of juvenile hormone III biosynthesis in vitro from honey bee corpora allata (CA), the glands responsible for JH production (Goodman and Cusson, 2012). Excised glands are incubated with methionine, which is a methyl donor to the ester function of the JH molecule (Metzler et al., 1972; Judy et al., 1973). Using radiolabelled methionine results in the production of radiolabelled JH III, which can then be quantified after partitioning into an isooctane phase. This technique was initially developed by Pratt and Tobe (1974) and Tobe and Pratt (1974), modified by Feyereisen and Tobe (1981) and adapted for use in honey bees (Rachinsky and Hartfelder, 1990, 1998; Huang et al., 1991). This approach is most useful when quantification of the activity of the glands, rather than circulating JH levels, is desired. Its difficulties lie primarily in the ability to surgically remove and handle the glands without damaging them prior to incubation.