passages.id: split_6_test_3548_passage
passages.type: progene_text
passages.text: The strategy , based on earlier evidence that sigma WhiG is limiting for sporulation ( K. F. Chater , C. J. Burton , K. A. Plaskitt , M. J. Buttner , C. MÃ?Â©ndez , and J. Helmann , Cell 59 : 133 - 143 , 1989 ) was to seek DNA fragments that inhibit sporulation in aerial hyphae when present at a high copy number .