sentences:  Carotenoids are precursors of many apocarotenoids that contain very important sex-specific precursors, trisporic acid (TSA) for the sexual reproduction of "Blakeslea trispora".Carotenes produced from carotenoids are further processed by carotene oxygenase to synthesize trisporic acid (TSA).TSA produced from carotene stimulates both sexually complementary cells to make contact with each other.