Fig. 5. Synthesis of DIF-1 made from the labelled polyketide, [3H]THPH, by prestalk and prespore cells. The products made from [3H]THPH by disaggregated slug cells (top two panels) or the prestalk and prespore fractions purified from them, were analysed by HPLC. THPH is successively converted to Cl-THPH, dM-DIF-1, DIF-1 and then to DIF-3, all of which are resolved (the unlabelled peaks preceding THPH are either impurities or produced in the work up). It can be seen that the prestalk fraction is capable of chlorinating THPH to Cl-THPH and dM-DIF-1, but methylation to give DIF-1/3 is barely detectable. By contrast, prespore cells and the starting mixture of cells (Disagg. cells) can perform all of these reactions. Cells were incubated at 107/ml in 1 ml NS/MES containing 1.9 nM [3H]THPH and 40 µM ancymidol (to inhibit breakdown of DIF-3). After 5 or 10 minutes at 22°C, labelled compounds were extracted, concentrated and resolved by HPLC, together with unlabelled standards. Each sample was analysed in duplicate.
