passages.id: split_1_test_1267_passage
passages.type: progene_text
passages.text: The ability of the A - ring reduced GSD derivatives to induce oestrogenic actions was evaluated by the use of two different molecular bioassays : (a) transactivation of a yeast system co - transfected with the human ER alpha ( hER alpha ) gene and oestrogen responsive elements fused to the beta-galactosidase reporter vector and ( b ) transactivation of the hER alpha - mediated transcription of the chloramphenicol acetyl transferase ( CAT ) reporter gene in a HeLa cells expression system .